Service Water System Problems Affecting Safety-Related Equipment (Generic Letter 89-13, Supplement 1)
ACCESSION #: 9003300128
UNITED STATES
NUCLEAR REGULATORY COMMISSION
WASHINGTON, D.C. 20555
April 4, 1990
TO: ALL HOLDERS OF OPERATING LICENSES OR CONSTRUCTION PERMITS FOR
NUCLEAR POWER PLANTS
SUBJECT: SERVICE WATER SYSTEM PROBLEMS AFFECTING SAFETY-RELATED
EQUIPMENT (GENERIC LETTER 89-13, SUPPLEMENT 1)
On July 18, 1989, the U.S. Nuclear Regulatory Commission (NRC) issued
Generic Letter 89-13, "Service Water System Problems Affecting Safety-
Related Equipment." On October 23, 1989, the NRC announced in the
Federal Register that it would hold four workshops on this generic
letter. The NRC conducted these workshops in Philadelphia, Atlanta,
Chicago, and Denver on November 28 and 30 and December 5 and 7, 1989,
respectively. The NRC answered written questions submitted through
appropriate project managers in the Office of Nuclear Reactor Regulation
before the first workshop and questions submitted at each workshop.
Transcripts of these meetings are available in the NRC Public Document
Room, 2120 L Street NW, Washington, DC.
This supplement contains the questions and answers read into the
transcripts during the workshops, except for the following changes.
Questions received in the general, Action I, and Action II categories
have been grouped according to topic. In addition, the NRC staff
modified some answers after the workshops with the aim of furnishing
additional guidance. Please contact the project manager if you have
questions on this matter.
Sincerely,
original signed by:
James G. Partlow
Associate Director for Projects
Office of Nuclear Reactor Regulation
Enclosures:
1. Questions and Answers
2. List of Recently Issued NRC Generic Letters
Technical Contact: C. Vernon Hodge, NRR
(301) 492-1169
. Enclosure 1
QUESTIONS AND ANSWERS
Page
I. GENERAL 2
A. Reporting Requirements 2
B. Backfit 4
C. Inspections 5
D. Miscellaneous 7
II. ACTION I - BIOFOULING 8
A. Terms 8
B. Inspection of Intake Structure 10
C. Biocide Guidance 14
D. Fire Protection Systems 16
III. ACTION II - HEAT TRANSFER TESTING 18
A. Testing Method 18
B. Maintenance of Heat Exchangers 23
C. Number of Heat Exchangers To Be Tested 26
D. Frequency of Testing or Maintenance 28
E. Schedule 29
F. Closed-Cycle Systems 31
G. Miscellaneous 33
IV. ACTION III - ROUTINE INSPECTION AND MAINTENANCE 34
V. ACTION IV - SINGLE-FAILURE WALKDOWN 36
VI. ACTION V - PROCEDURES REVIEW 39
.Generic Letter 89-13 -2-
Supplement 1
I. GENERAL
A. Reporting Requirements
1. If we are looking into several options to determine which one is the
most beneficial, however, [if] we have not made a decision by the
date that our response is due, would it be acceptable to explain
this and confirm that whatever option is chosen will be completed on
time? (Wisconsin Public Service)
Answer
Yes. The purpose of the 180-day response was to obtain the
commitments, plans, and schedules of licensees and applicants to
implement the recommended actions of the generic letter (GL) or
their equally effective alternatives. The licensee's or applicant's
decision-making process should be made a part of the plans and
schedules and submitted to the NRC when the response is due. If
other circumstances prevent such submittal, such as the regulatory
requirements of the technical specifications or outside government
agencies, the licensee or applicant should arrange any adjustments
of the schedule with the appropriate Office of Nuclear Reactor
Regulation (NRR) project manager.
2. What was the basis (experience) used to determine the schedule of
completion for Items 2 and 4? Do these schedules consider utilities
with more than one plant? (Northeast Utilities)
Answer
The basis for the schedule was an appearance of reasonableness. The
schedules given apply to single units. Schedules are intended to be
flexible and should be reported to the staff in the licensee's or
applicant's response with justification if the recommended schedule
in Generic Letter 89-13 is not used. The licensee or applicant
should arrange any adjustments of the schedule with the appropriate
NRR project manager.
3. If the CCWS [component cooling water system] is part of the scope
for Items IV, V of the generic letter, would it be possible to
modify the completion date commitments to fit this into our already
existing SSFI [safety system functional inspection] schedule?
(Wisconsin Public Service)
Answer
Yes. See the answer to Question I.A.1. Also, this request appears
to be reasonable for good cause. The licensee or applicant should
arrange any adjustments of the schedule with the appropriate NRR
project manager.
4. Can we defer the Unit 2 required action dates so that they coincide
with those of Unit 1 (i.e., October 1990 to April 1991 for Unit 2)?
(Houston Lighting and Power)
.Generic Letter 89-13 -3-
Supplement 1
Answer
Yes, with appropriate justification and arrangement with the
appropriate project manager.
5. For Action Items 4 and 5 of the GL 89-13, HL&P [Houston Lighting and
Power] plans to utilize the information gathered from a safety
system functional inspection (SSFI) for the essential cooling water
(ECW) and component cooling water (CCW) systems.
The SSFI for the ECW system supports the GL 89-13 reporting
requirements; however, the CCW SSFI is scheduled for 1990. Is it
acceptable to separate the reporting for the ECW and CCW systems,
that is, extend the CCW portion of GL 89-13? (Houston Lighting and
Power)
Answer
Yes. See the answers to Questions I.A.1 and I.A.3.
6. The SSFI method currently being used to satisfy Recommended Actions
IV and V is manhour intensive. Can program deficiencies identified
in the open-loop system be applied horizontally to the closed-loop
systems in lieu of an additional SSFI? (Houston Lighting and Power)
Answer
Yes. A licensee or applicant may extend identified deficiencies,
based on other actions already taken (such as an SSFI) on the open-
loop system, to the closed-loop system, provided the licensee or
applicant confirms that existing configuration control programs have
been applied to the closed-loop system.
.Generic Letter 89-13 -4-
Supplement 1
B. Backfit
1. The actions proposed by GL 89-13 constitute new staff positions. To
perform the testing and inspection requested by the GL, it may well
be necessary for licensees to make significant plant modifications.
For example, licensees will likely be forced to install new
instrumentation in order to perform tests and to monitor test
results. Furthermore, changes will be required of procedures. An
additional requirement of a walkdown has been made. The proposed
tests may be beyond the licensing basis of the plant. These
requirements seem to fit the definition of a backfit under 10 CFR
50.109(a)(1). Therefore, why were the requirements in the GL
promulgated under the provisions of Section 50.54(f)? (Nuclear
Utility Backfitting and Reform Group [NUBARG])
Answer
The NRC concluded that it was not assured that licensees and
applicants are in compliance with existing regulations, namely
General Design Criteria 44, 45, and 46 of Appendix A of 10 CFR Part
50 and Appendix B of that part. The recommended actions in this
generic letter do represent new staff positions and are considered a
backfit in accordance with NRC procedures. This backfit is to bring
facilities into compliance with existing requirements. The
regulatory request for information under 10 CFR 50.54(f) represented
by the generic letter is designed to gain this assurance.
2. Was a backfit analysis of the testing and inspection requirements
per formed? Will the staff make that analysis available to the
public? In particular, did the staff's backfitting analysis, if
any, justify the need for actions on closed systems? (NUBARG)
Answer
The staff performed an analysis for review by the NRC Committee to
Review Generic Requirements (CRGR). Because the CRGR reviews all
proposed bulletins and generic letters, among other proposed staff
actions, this may properly be referred to as a regulatory analysis
pursuant to 10 CFR 50.54(f). The CRGR analysis is available in the
NRC public document room (Accession No. 8907180077).
Indeed, the staff was not able to justify inclusion of closed
systems in the recommended actions of the generic letter, as it had
once proposed to do. Accordingly, the generic letter was issued
without the requirement for reporting heat transfer capability of
closed-cycle heat exchangers.
.Generic Letter 89-13 -5-
Supplement 1
C. Inspections
1. What level of detail should be included in the descriptions of
existing and proposed programs? (Philadelphia Electric)
Answer
The level of detail retained in plant records should be sufficient
to demonstrate that the heat removal requirements of the service
water system are satisfied. Each recommended action delineated in
the generic letter or equivalent should be addressed in sufficient
detail to demonstrate the licensee's evaluation of the action. It
should be noted that this information should be available in
appropriate plant records but need not be submitted to the NRC.
2. Generic Letter 89-13 provides the licensee with a great deal of
leeway in defining their programs. This leeway is desirable and
justifiable given the wide variation in conditions that may prevail.
It is anticipated that the main mechanism for judging compliance
with the generic letter will be NRC site inspections. During such
inspections, what will be the basis for judging the acceptability of
the program? What is being done to promote consistency in
interpretations among regions? (Duke Power)
Answer
The engineering judgment of the inspector, based on the addressee's
documentation for the program, will be relied upon to determine
accept ability of the program. The purpose of the generic letter is
for licensees and applicants to assure that the heat removal
requirements for the service water system are satisfied. This is
required by regulations, particularly General Design Criteria 44,
45, and 46 of Appendix A of 10 CFR Part 50 and Appendix B of that
part.
The workshops constitute to date the NRC effort to promote
consistency among the regions regarding Generic Letter 89-13. The
NRC will issue the questions and answers submitted before and during
the workshops as a supplement to Generic Letter 89-13 within the
next two months. The traditional method of issuing a temporary
instruction for inspection from headquarters to regional offices
will not be used for this generic letter. At this time, only audits
of implementation of Generic Letter 89-13 are planned rather than
systematic inspections. If an event or problem related to the
service water system occurs at a particular plant, that plant's
actions in response to Generic Letter 89-13 will be reviewed to
determine if inadequacies in the implementation of the Generic
Letter contributed to the event or problem. The supplement to
Generic Letter 89-13 will also reference the transcripts for these
workshops, which will be placed in the NRC public document room.
Authors of the generic letter will be available by telephone to
licensees, applicants, and inspectors to address questions on
implementation of the Generic Letter.
.Generic Letter 89-13 -6-
Supplement 1
3. Many of your responses this morning (Workshop II in Atlanta on
November 30, 1989) fall back to the standard NRC position that the
licensee should provide adequate assurance that they have a program
or actions in place to satisfy the generic letter concerns. This
position could create a problem later when the inspector shows up to
review our program. What kind of guidance will the NRR and RES
[Office of Nuclear Regulatory Research] staff be providing to the
inspector? If you don't provide specific instruction in something
like a TI [temporary instruction], the accept ability of a given
program will be left to the opinion of an individual inspector.
When will this type of guidance be available? (Florida Power)
Answer
Both the kind of guidance and the schedule are discussed in the
answer to the previous question, C.2.
4. When does the NRC envision inspections to begin on this letter?
(Florida Power)
Answer
At this time, only audits of implementation of Generic Letter 89-13
are planned rather than systematic inspections. The schedules for
such audits have not been determined at this time.
.Generic Letter 89-13 -7-
Supplement 1
D. Miscellaneous
1. Similar regional meetings regarding Generic Letter 89-04 were
conducted in the June 1989 time frame. To date, the minutes from
these meetings have not been received. When can we expect the
minutes from the Generic Letter 89-13 meetings? (Duke Power)
Answer
Concerning Generic Letter 89-04, the minutes were issued by letter
dated October 25, 1989, signed by James Partlow, Associate Director
for Projects, Office of Nuclear Reactor Regulation. The minutes are
being distributed to all licensees and applicants, meeting
attendees, NRR project managers, and the NRC public document room.
Concerning Generic Letter 89-13, see the answer to Question I.C.2.
To repeat, the NRC will issue the questions and answers submitted
before and during the workshops as a supplement to Generic Letter
89-13 within the next two months. The supplement to Generic Letter
89-13 will also reference the transcripts for these workshops, which
will be placed in the NRC public document room.
2. Do Recommended Actions IV and V apply to closed cooling systems?
(Kansas Gas and Electric)
Answer
Yes. The generic letter defines service water systems as including
both open-cycle portions and intermediate closed-cycle loops that
function to remove heat from safety-related structures, systems, or
components to the ultimate heat sink. Recommended Actions I, II,
and III specifically apply to open-cycle portions of the service
water system. Recommended Action II can be extended to the closed-
cycle portions as conditions warrant. Whether a cooling loop is open
or closed is not specified for Actions IV and V.
.Generic Letter 89-13 -8-
Supplement 1
II. ACTION I - BIOFOULING
A. Terms
1. What is the definition of layup? (Philadelphia Electric)
Answer
Layup is the treatment of a system that is isolated or in a standby
condition under stagnant flow conditions to prevent corrosion.
Refer to "Plant Layup and Equipment Preservation Sourcebook," EPRI
NP-5106 (March 1987). Those service water cooling loops normally
operated with water in the system, even in a standby condition,
should contain chlorinated or equivalently treated water rather than
untreated water.
2. What constitutes an infrequently used component? (Philadelphia
Electric)
Answer
Paragraph C in Enclosure 1 in the generic letter states that
redundant and infrequently used cooling loops should be flushed and
flow tested periodically at the maximum design flow to ensure that
they are not fouled or clogged. This recommended action refers to
emergency core cooling system loops or other safety-related cooling
loops that are normally in the standby condition. The next sentence
states that other components in the service water system should be
tested on a regular schedule to ensure that they are not fouled or
clogged. This recommended action refers to pumps, pipes, valves,
strainers, or other components even in loops in which water is
normally flowing. Often inadequate flow may exist in these loops
and not be detected without such testing.
Consider a system in which water is normally flowing that has
parallel branches in which the states of the components in the
branches are not often changed. For example, branch throttle valves
initially set before the plant began operation may not be controlled
by procedure. Subsequent changes in the throttle valve positions
for various reasons or clogging of them or other components in the
branches would upset the initial system flow balance without
detection.
3. Redundant and infrequently used cooling loops: (Unidentified)
a. Define infrequently used.
Answer
The wording "infrequently used cooling loops" is intended to
apply to those normally in a standby mode under stagnant flow
conditions. The Generic Letter 89-13 program should address
means for ensuring that fouling does not occur under such
conditions.
.Generic Letter 89-13 -9-
Supplement 1
b. If performance testing is done on all heat exchangers
periodically, will this satisfy the intent of the
recommendation?
Answer
Yes. Periodic performance monitoring of all safety-related heat
exchangers is acceptable, provided it ensures heat transfer
capability, not merely flow or pressure drop.
4. Recommendation I of Generic Letter 89-13 states that "initial
activities should be completed before plant startup following the
first refueling outage beginning nine months or more after the date
of this letter." What is the intent of the phrase, "initial
activities"? Does it mean:
The first "round" of activities (inspections, flushes, biocide
treatment, etc.) has been completed; or,
The mechanisms have been put in place which will culminate in the
implementation of the program (biocide discharge permits submitted,
procedures written and approved)? (Duke Power)
Answer
Both these possibilities could be included in the intent of the
phrase. For those activities involving an outside governmental
agency, the licensee or applicant should arrange a needed adjustment
in the schedule with the appropriate NRR project manager. For those
activities involving procedural changes or new procedures, "initial
activities" refers to those inspections or other activities by which
the need for procedural changes or new procedures is identified.
.Generic Letter 89-13 -10-
Supplement 1
B. Inspection of Intake Structure
1. When determining whether a plant has clams in its source water, does
consideration need to be given to the presence of clams in the plant
vicinity (local environment) or solely in the water body (source of
cooling water)? (Philadelphia Electric)
Answer
The purpose of this recommended action is to enable a licensee or
applicant to know if the service water system might be subject to
biofouling. All potential sources of water for the service water
system should be examined annually for the presence of biofouling
species. If no waters in the local environment of a plant can get
inside piping and components to cause biofouling degradation of the
heat transfer function of the service water system, then such waters
do not need to be sampled.
2. Enclosure 1 to Generic Letter 89-13 recommends varying requirements
for service water systems based on intake structure configuration
and location. In a service water system in which the suction point
of the service water pumps is in the collecting basin for the
ultimate heat sink (cooling tower) would the basin be considered the
intake structure or would the source of basin makeup water be
considered the intake structure? (Mississippi Power and Light)
Answer
Each licensee or applicant should define the scope of the intake
structure. The NRC considers that an intake structure would contain
all the waters eventually used in the system. See the answer to
Question II.B.1.
3. Does the visual inspection of the intake structure apply to the
intake piping as well? If so, will NRC give guidance as to
replacement criteria of piping? If not, is [American National
Standards Institute Standard] B31.1 for wall thinning the
appropriate criteria? (Wisconsin Public Service)
Answer
Visual inspection of the intake structure may apply to the intake
piping. The minimum wall thickness is defined by the code of record
that was used to design the piping system. Before 1971, ANSI B31.1
was applicable. Since 1971, ASME Code Section 3 applies to piping
design and fabrication.
4. When stating we should be aware of other plants (refer to
Philadelphia workshop transcript, p. 21), facilities, etc., that use
the same service water source (e.g., river) and their biofouling
problems, how far does that extend? Within 5 miles? 50 miles?
Please clarify. (Unidentified)
.Generic Letter 89-13 -11-
Supplement 1
Answer
The NRC cannot place a quantitative range on biofouling awareness.
Conditions at each site would determine an appropriate program or
how far away to monitor for biofouling. The licensee or applicant
should use the best available site-specific information and
establish an appropriate monitoring program.
5. Refer to Action Item I in Gen. Ltr 89-13. If the current sampling
program, which was initiated to detect Asiatic clams, has not found
any mollusk infestation do the sampling methods need to be modified
to detect Zebra mussels? (Niagara Mohawk Power)
Answer
The recommended sampling methods in Recommended Action I are
intended to be general enough to enable licensees and applicants to
become aware of macrobiofouling agents early enough to prevent the
associated fouling problem from adversely affecting the safety-
related function of the service water system. See Information
Notice 89-76, "Biofouling Agent: Zebra Mussel."
6. Inspection of intake structure each refuel cycle. Could inspection
of other intake structures (fossil units) on the same body of water
that have been in place and in service for up to 40 years be used to
justify either to extend the frequency of inspection or maybe no
inspection at all? (Unidentified)
Answer
The inspection of the intake structure should not be restricted to
potential macroinvertebrate fouling. If the program in place at the
fossil unit mentioned has been shown to be effective to date for
detecting of fouling, including biofouling, mud, and silt, then it
may be sufficient for future monitoring. However, the licensee or
applicant should be aware of and should consider possible rapid
changes in environmental conditions and ensure that its program
includes the best available site-specific information.
7. If it can be shown that the introduction of mollusks into the
service water system is not plausible based on service water system
design and makeup water system design, can the requirements of
Generic Letter 89-13 concerning both inspection for and control of
mollusks be waived? (Mississippi Power and Light)
Answer
The purpose of the generic letter is for licensees and applicants to
assure that the heat removal requirements for the service water
system are satisfied. If this can be done by the proposed program,
then it is acceptable.
.Generic Letter 89-13 -12-
Supplement 1
8. If yearly inspection of a plant's service water intake structure
shows no indication of Asiatic clams, and testing results indicate
that corrosion is not microbiologically influenced, is it acceptable
to continue with the annual inspections for clams and perform
maintenance and testing as required in Actions II and III of GL
89-13, in lieu of a chlorination injection program? (Commonwealth
Edison)
Answer
This appears to be reasonable for good cause shown. See the answers
to the previous two questions.
9. Larva sampling is difficult to do. We already have a sampling
commitment, but we don't want to do this and can justify not doing
it. (Kansas Gas and Electric)
Answer
An equally effective course of action with justification is
acceptable. However, the earlier that a licensee or applicant can
identify the presence of a biofouling species in a source body of
water for the service water system, the better chance it will have
to control the situation and prevent a potential safety problem.
10. Does the generic letter imply that biofouling monitoring methods are
required? Are sidestream or inline monitoring methods necessary?
Does the NRC have a preference concerning the methods of visual, UT
[ultrasonic testing], radiography, or electrochemical (Corrator)
probes to monitor for biofouling? (South Carolina Electric and Gas)
Answer
Biofouling monitoring of the source water would generally be
necessary. Licensees and applicants may use, however, equally
effective programs for Recommended Action I. Sidestream or inline
monitoring is effective and could be used for this purpose. The NRC
has no preference concerning methods for biofouling monitoring or
nondestructive service water system examination provided the
selected method is effective.
11. For NTOL [near-term operating license] plants, when does GL 89-13
have to be implemented? (Unidentified)
Answer
As stated in Generic Letter 89-13, both licensees and applicants
should observe the same schedule. The licensee or applicant should
arrange any justified adjustments of the schedule with the
appropriate NRR project manager.
12. On Item C, Enclosure 1, since macroscopic biological fouling and MIC
[microbiologically influenced corrosion] have not been problems at
CNS [Cooper Nuclear Station], does that exempt us from the
recommendation for chlorinating systems using raw water before
layup? (Nebraska Public Power District)
.Generic Letter 89-13 -13-
Supplement 1
Answer
Yes, if appropriate justification is provided.
13. Is periodic maintenance adequate to address layup without
chlorination? (Nebraska Public Power District)
Answer
Yes, if appropriate justification is provided.
14. On Item D, Enclosure 1, in lieu of taking annual water samples to
determine if Asiatic clams have populated the water source, could we
perform annual visual inspections of sample heat exchangers cooled
by river water? (Nebraska Public Power District)
Answer
The purpose of sampling the water source itself was to ensure that
means of potential fouling were identified early. However, if the
best avail able site-specific information does not indicate a means
of biofouling, then visual examination of a sample of service water
system heat exchangers may be sufficient, with proper justification,
to detect fouling.
.Generic Letter 89-13 -14-
Supplement 1
C. Biocide Guidance
1. Enclosure 1 to Generic Letter 89-13 describes an acceptable program,
to the NRC, to implement Recommendation No. I of the generic letter.
This program includes biocide treatment regardless of whether the
plant is susceptible to macroscopic biological fouling or not. Will
a program that does not include biocide treatment be acceptable to
the NRC? (Duke Power)
Answer
Yes, if good cause is shown. Note the guidance in Paragraph B of
Enclosure 1 to Generic Letter 89-13. Chlorination or equally
effective treatment is included for freshwater plants without clams
because it can help prevent microbiologically influenced corrosion.
2. With regards to Enclosure 1 of the generic letter; (Wisconsin Public
Service)
a. Will NRC give guidance on use of biocides other than chlorine?
Answer
No. The NRC is interested in the effective heat transfer of the
systems. It is not in a position to consult on the various biocide
treatments. Refer to "Plant Layup and Equipment Preservation
Sourcebook," EPRI NP-5106 (March 1987).
b. Do we need to continuously chlorinate, if under our inspection
program, we find no evidence of macroscopic fouling? Do WPDES
[sic; National Pollutant Discharge Elimination System]
discharge limits take precedence to this?
Answer
No. The program described in Enclosure 1 represents an
acceptable program for implementing Recommended Action I. A
licensee or applicant can choose to pursue an equally effective
alternative course of action if justified. Precautions should
be taken to obey Federal, State, and local environmental
regulations regarding the use of biocides. This includes the
National Pollutant Discharge Elimination System (NPDES)
discharge limits administered by the U.S. Environmental
Protection Agency, which were referenced in the question.
c. Is demineralized water acceptable for use in wet layup of
stagnant SW [service water] piping?
.Generic Letter 89-13 -15-
Supplement 1
Answer
This question must be decided by the licensee or applicant.
The result should be that the heat removal requirements for the
service water system are satisfied. To accomplish this, the
NRC recommends that such piping be flushed and flow tested
periodically to ensure that clogging is absent and that
chlorinated or equivalently treated water will be used to fill
service water loops before layup to help prevent MIC. We note
also that industry recommends treatment of service water
systems during outages to prevent microbes. See EPRI NP-5106.
3. Some State regulations do not permit the use of biocides above the
minimum detectable level, yet Enclosure 1 to the GL appears to
require biocides while cautioning plants not to violate State and
local regulations. Since it is not possible in some jurisdictions
to use any biocides without violating State and local regulations,
what alternatives to biocides are acceptable to the staff? (Nuclear
Utility Backfit Action Reform Group [NUBARG])
Answer
An alternative course of action is acceptable if the heat removal
requirements for the service water system are satisfied. Biocides
can be deactivated before discharge. The treated biocides must meet
NPDES discharge limits. At least one utility (Trojan) is
deactivating the biocides before discharge. See the answers to the
previous two questions.
.Generic Letter 89-13 -16-
Supplement 1
D. Fire Protection Systems
1. To what extent should fire protection systems be addressed in
response to the generic letter? (Philadelphia Electric)
Answer
The generic letter is not designed to focus on fire protection
systems, which are not safety-related, but to incidentally include
them if they use untreated water that could be subject to the
service water system problems described in the generic letter.
2. We use well water (raw water) as a source to the fresh water/fire
protection storage tanks. Do we need to chlorinate these tanks or
do we need to conduct full-flow surveillance tests on all fire
protection piping runs? We presently only surveil the fire pumps for
flow, not the piping runs. We do not presently chlorinate these
tanks. The SW system per se is not used to fill these tanks;
separate well pumps are used. (Public Service Electric and Gas)
Answer
The recommended program described in Enclosure 1 of the generic
letter was developed under a government-sponsored research program.
If a licensee or applicant chooses an alternative course of action
from that recommended in Enclosure 1, it should assess the
potentials for macroscopic biofouling and microbiologically
influenced corrosion (MIC) and justify that the alternative course
of action will result in satisfaction of the heat removal
requirements for the service water system.
Paragraph B of Enclosure 1 of the generic letter recommends
chlorination whenever the potential for a macroscopic biological
fouling species exists. Such a potential may not exist for these
wells, but the potential for MIC should also be considered.
Paragraph C of Enclosure 1 of the generic letter recommends periodic
flow testing of infrequently used loops at the maximum design flow
to ensure that they are not fouled or clogged. If the fire
protection piping runs are subject to biofouling but the water is
not treated to protect against biofouling, then full-flow testing of
the runs may be appropriate to ensure that the potential for
clogging is minimal. This paragraph also recommends chlorination to
help prevent MIC.
.Generic Letter 89-13 -17-
Supplement 1
3. Do Generic Letter 89-13 requirements apply to the fire protection
systems which are not fed by either the service water system or the
service water Intake? (South Carolina Electric and Gas)
Answer
The generic letter is not designed to focus on fire protection
systems, but to incidentally include them if they use untreated
water that could be subject to the service water system problems
described in the generic letter.
4. What is the basis for requiring treatment of fire protection systems
that use raw service water as a source (Enclosure 1, Section C)?
(NUBARG)
Answer
See the answers to the previous two questions.
5. For a fire protection system supplied by raw water which meets flow
requirements and does not provide safety-related cooling, are any
actions required? (Iowa Electric Light and Power)
Answer
No. See the answer to Question II.D.1.
.Generic Letter 89-13 -18-
Supplement 1
III. ACTION II - HEAT TRANSFER TESTING
A. Testing Method
1. Should the proposed heat exchanger heat transfer testing method be
provided for prior NRC review and approval? (Philadelphia Electric)
Answer
No.
2. Has the NRC reviewed the EPRI SWWG [Electric Power Research
Institute Service Water Working Group] document prepared by Duke
Power and Toledo Edison describing several methods of heat transfer
testing? If so, is the temperature effectiveness method acceptable?
Which methods are accept able? (Philadelphia Electric)
Answer
The staff has not formally reviewed this document but has received a
draft copy. A method of heat transfer testing is acceptable for
purposes of satisfying the generic letter if it can assure that the
heat removal requirements for the service water system are
satisfied.
3. If the pressure drop across a heat exchanger at design flow is less
than or equal to the manufacturer's specification, is heat transfer
testing required, provided the baffles have been inspected to ensure
that the flow is not bypassing the coils? (Philadelphia Electric)
Answer
The objective is not to satisfy the manufacturer's specification for
flow in a heat exchanger so much as it is to ensure that the heat
removal requirements for the service water system are satisfied. If
the latter assurance can be achieved by showing design flow to be
necessary and sufficient, then heat transfer testing would be
superfluous.
4. Page 5, paragraph 3. What is meant by "The relevant temperatures
should be verified to be within the design limits?" Does this imply
testing should be conducted with the design-basis heat load? Is it
acceptable to conduct testing for all heat exchangers at off normal
conditions, provided accurate and relevant data can be acquired, and
analytical methods used to determine the heat transfer capacity at
design conditions? (Portland General Electric)
Answer
Enclosure 2 of the generic letter discusses in detail verifying
various parameters to be within design limits. Testing with design-
basis heat loads is recommended ideally. If testing can be done
under design conditions, it should be done under those conditions.
Realizing this may not be practicable in nonaccident circumstances,
the next best step is to
.Generic Letter 89-13 -19-
Supplement 1
conduct tests under off-design conditions and analytically correct
the results to the design conditions. Such a procedure is
acceptable if it is necessary but not if testing under design
conditions is practicable.
5. For heat exchangers that cannot be tested at the design heat removal
rate, what is the NRC-recommended method to extrapolate the test
data to design conditions? Does the NRC have any additional
recommendations for extrapolating test data taken at very low loads
(less than 10% design load) to design conditions? (Southern
California Edison)
Answer
The staff does not have a recommended method of extrapolation.
However, the EPRI service water system working group has been
developing such guidance as have some licensees such as Duke Power.
These may be places to start when developing appropriate testing
programs.
6. Recommended Action II requires that "the relevant temperatures
should be verified to be within design limits." Also, Enclosure 2,
Item II.A states, "Perform functional testing with the heat
exchanger operating, if practical, at its design heat removal rate
to verify its capabilities. Temperature and flow compensation should
be made in the calculations to adjust the results to the design
conditions."
It is not practical to test the heat exchangers at design heat
removal rates. Also, we are unable to find a method which has the
requisite level of precision to adjust the test results to design
conditions.
Please discuss an acceptable method to adjust the test results to
the design conditions. Also provide the scientific bases, or a
reference, for the proposed method.
Also, the heat removal test cannot be performed on the containment
spray heat exchangers because there is no heat source. The only
test that can be performed is a pressure drop test. Is this
acceptable? If not, what is recommended? (Indiana and Michigan
Power)
Answer
As mentioned previously, the NRC does not have a recommended test
method. See the answer to the previous question. With regard to the
testing of containment spray heat exchangers, as of all safety-
related heat exchangers, a pressure drop test alone is not
sufficient to satisfy the indicated heat transfer capability
concerns. If it is not practicable to test a heat exchanger, then
the licensee or applicant may propose a program of periodic
inspection, maintenance, and cleaning as an alternative. We are
aware, however, of one licensee who was able to test the containment
spray heat exchanger by heating the refueling water storage tank
water approximately 10 F and then performing temperature monitoring
tests as well as pressure drop tests.
.Generic Letter 89-13 -20-
Supplement 1
7. To what degree should a utility endeavor to monitor real-time
corrosion rates of the service water system? Is trending of heat
exchanger performance and visual inspections sufficient
documentation of the component's internal condition? (South
Carolina Electric and Gas)
Answer
It is not necessary to determine numerical real-time corrosion rates
in the service water system. The licensee's or applicant's
monitoring program should be sufficient to identify degradation and
to take the necessary corrective action before system performance is
unacceptably affected. Trending of data is a recommended approach
to monitoring system performance.
8. Is the NRC staff stating that a technical evaluation of a heat
exchanger's capability to perform its design safety function cannot
be used in lieu of initial testing? Therefore, all heat exchangers
must be tested and even maintenance/cleaning cannot be used in lieu
of initial testing because it would require a technical evaluation
to determine maintenance/cleaning frequency. Also, when considering
several identical heat exchangers in one loop, do all the heat
exchangers require testing or maintenance/cleaning? (Philadelphia
Electric)
Answer
No, the initial heat exchanger "test" program may consist of both
performance testing of some heat exchangers and maintenance and
cleaning of others. The initial test program was intended to ensure
that the licensee or applicant has established a baseline for all
safety-related heat exchangers served by the service water system
and, therefore, is confident that they can perform their heat
removal function. As further clarification, if there are several
identical heat exchangers in one service water loop, a licensee or
applicant may perform testing or develop a maintenance and cleaning
program for these heat exchangers based on the most limiting one as
part of its initial "test" program. Justification for the basis of
comparable service conditions should be included in the evaluation
when all identical heat exchangers are not tested.
9. Refer to Action Item II of Gen. Ltr 89-13. Can the test program
include data taken during routine operating intervals, with minimum
load on heat exchangers, and extrapolated to substantiate adequate
HX [heat exchanger] performance? Or when does the NRC consider it
impractical to test a HX at the design heat removal rate? (Niagara
Mohawk Power)
Answer
Yes, if testing under design conditions is not practicable. See the
answers to Questions III.A.4, III.A.5, and III.A.6 above. The
licensee or applicant should determine whether such testing is
practicable. See the answer to Question III.A.14.
.Generic Letter 89-13 -21-
Supplement 1
10. In Enclosure 2 of the generic letter, a statement is made that
testing should be done with necessary and sufficient
instrumentation. Flow measurement is one of the two key parameters
when measuring heat exchanger performance. It is also the most
difficult since most plants never provided means to measure
individual flow rates to service water users. In general, orifice
plates, venturi tubes, pitot tubes and flow nozzles are the only
recognized traceable type of flow measuring devices, all of which
require intrusive elements. To be able to utilize such devices
would require plant system modifications at great expense to the
utility and its customers. A less expensive alternative to this
would be to use non-intrusive, non-traceable devices such as
transit-time ultrasonic flow meters which with current technology
give very reliable results. Trending of data taken with such
devices would appear to be equally effective for detecting
degradation in cooling water systems. Would the NRC recognize the
value and benefit of using such devices and accept programs which
utilize them? (Detroit Edison)
Answer
Yes.
11. Thermographic cameras could potentially be used to scan the tubes on
air to water heat exchangers to see temperature profiles of the
tubes and detect tube blockage or sediment in the tubes. Will the
NRC accept such qualitative checks rather than quantitative
measurements to prove that a heat exchanger is not fouled? (Detroit
Edison)
Answer
Yes. However, additional means should be included in the program to
ensure adequate heat transfer.
12. If off-the-shelf software is reviewed for technical adequacy and
subsequently utilized to perform heat exchanger performance
calculations, will it be acceptable to the NRC? (Detroit Edison)
Answer
Yes.
13. If a heat exchanger performance test reveals that a heat exchanger
is in a degraded condition, the first obvious question will be as to
what the impact of the degraded condition is on system operability.
Will a heat exchanger performance program be considered the same as
the plant's surveillance program with the same ramifications for
questioning plant/system operability? If so, is the NRC considering
asking the licensees to include limiting condition for operation
statements in their technical specifications? (Detroit Edison)
.Generic Letter 89-13 -22-
Supplement 1
Answer
If a heat exchanger's heat transfer capability is shown to be
degraded below levels needed for performance of its safety-related
function, it is considered inoperable. The staff does not intend
that elements of these programs be included in plant technical
specifications.
14. Restate what you would consider acceptable as "impractical
conditions for testing." What are "acceptable alternatives,"
especially for utilities not privy to EPRI information? (Portland
General Electric)
Answer
An impractical condition would be a situation where flow or the
means of applying a heat load cannot be achieved because of system
configuration. An acceptable alternative is a periodic inspection or
maintenance program for such heat exchangers. Impracticality itself
is not a sufficient reason for excluding any heat exchanger from
some verification of performance.
15. What if performable HX testing conditions (off design) cannot be
used to demonstrate acceptable heat transfer (i.e., low delta T
combined with instrument accuracies)? Is maintenance inspection our
only alternative? (Portland General Electric)
Answer
If reasonable results cannot be obtained from performance testing,
then inspection or maintenance is an appropriate alternative. A
licensee may, however, be able to justify another acceptable
alternative.
16. If the utility performs a baseline test that exceeds the design
requirements but is below the mfg [manufacturer's] rating for this
component HX, does the NRC consider this as a concern in that
"design margin" has been lowered? (Arkansas Power and Light)
Answer
No. The staff's concern is not that a licensee or applicant
maintain the initially specified design margin. If the licensee or
applicant chooses to operate with a reduced margin, this is
acceptable provided the safety-related heat removal requirements are
satisfied.
.Generic Letter 89-13 -23-
Supplement 1
B. Maintenance of Heat Exchangers
1. To what extent can routine maintenance/cleaning of heat exchangers
replace testing? (Philadelphia Electric)
Answer
A licensee or applicant should determine the appropriate frequency
of testing or maintenance activities to ensure that the heat removal
requirements for the service water system are satisfied. For a
given heat exchanger, a licensee or applicant may elect to clean,
replace, repair, or otherwise maintain it initially before beginning
a routine testing program. If the licensee or applicant elects to
not implement a routine testing program for the heat exchanger, then
a routine maintenance program may be necessary to provide the sought
assurance. In the absence of a routine test program, no basis may
be available for detecting potential degradation of heat transfer
performance. In the absence of such a basis, the frequency of
maintenance may have to be a maximum value to provide the sought
assurance.
2. Page 5, paragraph 4. If the maintenance period is known why can't a
test be performed before maintenance to establish a data point for
the required testing or maintenance? If the overall maintenance
period has been 3 or more fuel cycles could this be used to
establish the test frequency? Is it necessary to retest a heat
exchanger after maintenance if the work performed was a restoration
only (i.e., cleaning not tube plugging) and testing had previously
been conducted with clean heat transfer surfaces? (Portland General
Electric)
Answer
All these steps are acceptable alternatives to the program outlined
in Enclosure 2 in the generic letter. The justifications that these
alternative procedures ensure that the heat removal requirements for
the service water system are satisfied should be documented and
retained in appropriate plant records.
3. Recommended Action II paragraph 5 states that frequent regular
maintenance is an acceptable alternative to testing. What is meant
by "frequent regular maintenance"? Does this mean more frequently
than if testing were performed? This paragraph further states that
this alternative might apply to small heat exchangers, . . . located
in low radiation areas. . . . Would low radiation areas be defined
by ALARA [as low as is reasonably achievable] practices or less than
100 mr/hr? (Unidentified)
Answer
The licensee or applicant is to establish the frequency of periodic
testing or regular maintenance once sufficient data have been
collected. The frequency should ensure that unacceptable degradation
does not occur between testing or maintenance cycles. Low radiation
areas as intended in Generic Letter 89-13 are included in the
licensee's ALARA program so that
.Generic Letter 89-13 -24-
Supplement 1
radiation levels will not preclude personnel access for maintenance
and cleaning of heat exchangers.
4. GL 89-13 seems to imply that periodic maintenance (i.e., cleaning)
of small accessible heat exchangers is acceptable in lieu of
performance testing. If so, is a refueling maintenance frequency
acceptable? (Northeast Utilities)
Answer
Yes. This is an acceptable initial frequency and may be acceptable
in the long-term with justification based on data from a minimum of
three refueling outages.
5. If maintenance is performed in lieu of testing for degraded
performance of the heat exchanger, how extensive does the
maintenance have to be? That is, does maintenance have to be
performed on both sides of the HX or just on the service water side?
(Niagara Mohawk Power)
Answer
Maintenance should be extensive enough to assure the heat removal
requirements of the service water system are satisfied. See the
answers to Questions III.B.1 and III.F.1.
6. Would a program involving inspection and maintenance activities in
lieu of a performance test program be an acceptable program for all
heat exchangers and components? (Nuclear Utility Backfit Action
Reform Group [NUBARG])
Answer
Yes, if justification is provided.
7. Clarification of Item IV. B., Enclosure 2, on periodic visual
inspection of small heat exchangers such as seal coolers. Are they
included in the class to be inspected when the pump is inspected?
(Nebraska Public Power District)
Answer
If the seal coolers in question are integral parts of larger
components, such as pumps, then the coolers may be inspected
visually during the regularly scheduled disassembly of the larger
component. If not, then the seal coolers should be treated
separately. Once it has been established that a small heat
exchanger such as a seal cooler is performing satisfactorily, the
licensee or applicant may choose to justify an extended program of
periodic inspection (e.g., up to 5 years) on the basis of existing
operating conditions, such as the cooling of loops not subject to
fouling mechanisms.
.Generic Letter 89-13 -25-
Supplement 1
8. ANO [Arkansas Nuclear One] is scheduled to chemically clean the
entire SW system in the fall of 1990. Does this constitute an
acceptable method to restore thermal performance in lieu of
performance testing for the first outage? (Arkansas Power and
Light)
Answer
The licensee or applicant should justify such an approach to satisfy
this part of the generic letter. Since chemical cleaning is a
corrective action, some followup verification such as visual
examination or limited performance testing may be appropriate.
.Generic Letter 89-13 -26-
Supplement 1
C. Number of Heat Exchangers To Be Tested
1. Is it acceptable to determine the most restrictive heat exchangers
in each group for testing in lieu of testing every heat exchanger?
(Philadelphia Electric)
Answer
The purpose of the generic letter is for licensees and applicants to
assure that the heat removal requirements for the service water
system are satisfied. If this can be done by the proposed program,
then it is acceptable.
2. How much detail does the NRC expect for the response to Action II?
Would the proposed test/maintenance/inspection method for each
heat exchanger be necessary? (Public Service Electric and Gas)
Answer
Specific details of the licensee's or applicant's program in
response to Action II should be developed and retained as part of
plant records. Those heat exchangers not being included in programs
under Action II should be identified and the basis given for their
exclusion. Grouping of heat exchangers into categories based on the
approach to be used would be acceptable.
3. Enclosure 2, page 2. The term "all heat exchangers" is used. Does
this imply every heat exchanger of a given design must be tested or
where more than one identical heat exchanger is used can one
representative unit be selected? (Portland General Electric)
Answer
Recommended Action II calls for the testing of the heat transfer
capability of all safety-related heat exchangers cooled by service
water. The service water system is defined as the system or systems
that transfer heat from safety-related structures, systems, or
components to the ultimate heat sink. Each heat exchanger,
regardless of redundancy, should be tested or maintained initially
to establish that the heat removal requirements for the service
water system are satisfied. Existence of identical conditions then
can be used to determine the best test or maintenance frequencies to
ensure that the heat removal requirements for the service water
system are satisfied.
4. We would like to limit heat exchanger performance testing to one
unit since the two units are identical. Is this an acceptable
approach? (Houston Lighting and Power)
Answer
Not totally. See the answer to the previous question.
.Generic Letter 89-13 -27-
Supplement 1
5. Is it acceptable to eliminate heat exchangers from the testing
requirement of Action II if they are in parallel and/or in series
with other heat exchangers which are tested and operated under
similar service conditions (e.g., velocity, temperature, process
fluid) (Ref. EPRI Heat Exchanger Performance Monitoring Guidelines
for Service Water Systems)? (Common wealth Edison)
Answer
Not totally. See the answer to Question III.C.3.
.Generic Letter 89-13 -28-
Supplement 1
D. Frequency of Testing or Maintenance
1. Recommendation No. III [sic] does not specify a frequency for heat
exchanger inspections. Is it the NRC's intent that the utility
establish the frequency of these inspections? (GPU Nuclear)
Answer
Yes. Recommended Action II indicates limits. Initially, tests
should be conducted at least once every fuel cycle. More frequent
testing may be necessary to enable a conclusion that the heat
removal requirements for the service water system are satisfied.
After about three tests, a licensee or applicant may be in a
position to set a different testing frequency. However, the finally
determined testing frequency should not be less than once every 5
years.
2. Page 6, paragraph 1. Why were three tests chosen? Could a
different number, more or less, be appropriate? (Portland General
Electric)
Answer
The number three is the minimum number needed to establish a trend.
A larger number would be appropriate, but a smaller number is
insufficient.
3. Page 5, paragraph 5. What is meant by frequent regular maintenance?
Can frequency be determined in a similar method as test frequency?
(Portland General Electric)
Answer
Frequent regular maintenance is an acceptable alternative to
Recommended Action II, which calls for heat exchanger performance
testing. For small heat exchangers such as lube oil coolers,
testing might be excessively burdensome compared with maintenance of
the heat exchangers. A licensee or applicant can choose to
routinely maintain the heat exchangers instead of testing them.
Either the frequency of maintenance or the frequency of testing
should be determined to ensure that the equipment will perform the
intended safety functions during the intervals between maintenances
or tests.
.Generic Letter 89-13 -29-
Supplement 1
E. Schedule
1. In an effort to minimize the amount of time that a single, redundant
division of safety-related equipment is out of service some
utilities employ a "divisional outage" concept for major planned
plant outages. By utilizing this concept significant maintenance
work activities, i.e., system flow balance test, standby D/G [diesel
generator] teardowns, electrical distribution bus work, etc., are
performed on an alternating outage schedule for each division. This
permits comprehensive maintenance on each division to be performed
while reducing the overall impact on redundant safety system
availability.
The ability of a utility to implement and maintain a service water
heat removal capability monitoring program would be significantly
enhanced by the installation of permanent plant monitoring
equipment. Installation of dedicated monitoring equipment would
also reduce the impact of future testing on service water and heat
exchanger availability.
For a utility that employs the "divisional outage" concept and
wishes to install permanent plant equipment to perform the system
testing identified in Generic Letter 89-13, is it permissible to
defer baseline data acquisition for one division of the service
water system until the second refueling outage following the
issuance of the generic letter? (Mississippi Power and Light)
Answer
This request appears to be reasonable for good cause. Any request
for an adjusted schedule should be arranged through the appropriate
project manager in the Office of Nuclear Reactor Regulation (NRR) of
the NRC.
2. In reference to Recommended Action II of Generic Letter 89-13.
(Niagara Mohawk Power)
Asking an item of clarification Do all safety-related heat
exchangers connected to or cooled by service water or raw water have
to be tested or verified clean by maintenance, to insure
satisfaction of the heat removal requirements, prior to plant
startup following the first refueling outage beginning 9 months or
more after the issuance of Gen. Ltr 89-13?
Answer
Yes.
Reason for asking If a heat exchanger was cleaned 13 or possibly
18 months prior to issuance of Gen. Ltr 89-13 and found to be clean
or tested and found acceptable and the current program does not call
for recleaning or testing for 3 years then the program would have to
be revised. Also trend data may already exist indicating that there
is no need to clean or test on less than a 5-year interval. [This
would also hold] if the heat exchanger is part of a larger component
that is not scheduled for maintenance.
.Generic Letter 89-13 -30-
Supplement 1
Answer
The generic letter is designed to provide flexibility in determining
a justifiable alternative program for testing. The goal of the
letter is to ensure that the heat removal requirements for the
service water system are satisfied.
.Generic Letter 89-13 -31-
Supplement 1
F. Closed-Cycle Systems
1. What is really required by the sentence on adequacy of chemistry
control programs in the first paragraph of page 5 of the generic
letter? (Kansas Gas and Electric)
Answer
Even though a closed cooling loop may contain water with controlled
chemistry, the loop might be contaminated as a result of inleakage,
inadequate chemistry controls, or materials in the system before the
current chemistry control program became effective. An example of
this was recently disclosed at the EPRI Service Water System
Reliability Improvement Seminar at Charlotte, North Carolina, on
November 6-8, 1989. In the internal study discussed there, optical
examination of the primary side of the decay heat removal (DHR) heat
exchanger (HX) tubes disclosed no fouling. The tubes were shiny
bright. Optical examination of the closed component cooling water
(CCW) HX, however, disclosed significant fouling. The tubes did not
reflect any light. The problem was a paraffin-based packing
material inadvertently left in the system when the plant was being
constructed.
Suppose the licensee in this case can argue that it has a chemistry
control program for water circulating through the CCW HX, but cannot
show that the program has been in place since the system was filled
initially. A proper response to the generic letter then would
include testing the CCW HX. At any point in the program, if a
finding of degraded heat transfer cannot be explained or remedied by
maintenance in the open-cycle portion of the system, as would be
possible in this case, the CCW HX should be tested and, depending on
those results, the DHR HX should be tested. The process should be
continued until the problem is remedied.
2. Does our CCWS [component cooling water system] need to be addressed
as part of our response? We have recently shown, through eddy
current testing of the CCW HTX's [heat exchangers], that the
physical barrier between SW [service water] and CCW is adequate.
Makeup to the CCW is via makeup water. (Wisconsin Public Service)
Answer
Not necessarily. See the answer to the previous question.
3. Page 5, paragraph 1. What level of documentation is required to
justify excluding closed-cycle system heat exchangers from testing
to verify heat transfer capability? (Portland General Electric)
.Generic Letter 89-13 -32-
Supplement 1
Answer
The goal of the generic letter is to obtain assurance that the heat
removal requirements for the service water system are satisfied. To
exclude a closed-cycle system heat exchanger from testing, a
licensee or applicant should show that the chemistry of the primary
fluid and the heat transfer characteristics of the heat exchanger
have been controlled since the system was first filled.
4. The ACRS [Advisory Committee on Reactor Safeguards] June 14, 1989,
letter to the Commission noted five areas of concern with which
NUBARG agrees. Some of the concerns were accommodated in the GL;
however, we are interested to know the resolution of the following.
(Nuclear Utility Backfit Action Reform Group [NUBARG])
a. An intermediate closed cooling water system is exempt from the
GL provided it is not subject to significant sources of
contamination, is chemistry controlled, and does not reject
heat directly to a heat sink. However, the adequacy of the
chemistry control program must be verified over the total
operating history of the plant. The ACRS questioned whether
the absence of an adequate water chemistry control system over
any part of the operating history of a closed-cycle system was
adequate justification for including the system within the
scope of the GL. How did the staff resolve this concern?
Answer
The staff relaxed its position on including closed-cycle
cooling systems in Recommended Action II but added the
precautionary recommendation that if degradation of heat
transfer could not be explained or remedied by maintenance of
the open-cycle part of the service water system, then testing
may have to be selectively extended to the closed-cycle part of
the system. See the answer to Question III.F.1.
b. Are plants required to review closed cooling water system
operating logs for the history of the plant to verify adequate
chemistry control?
Answer
Licensees and applicants are required to assure that the
safety-related heat removal requirements for the service water
system are satisfied. If review of closed cooling water system
operating logs for the history of the plant can help provide
this assurance, then that review would be an acceptable part of
the program.
.Generic Letter 89-13 -33-
Supplement 1
G. Miscellaneous
1. Do both emergency service water systems and normal service water
systems need to be reviewed? (Kansas Gas and Electric)
Answer
In some cases this may be necessary. The NRC is concerned about the
safety-related effects of both systems. Sometimes the mode of
operation of a service water system is changed under emergency
conditions. This change may result in the introduction of
uncontrolled water and thus the potential introduction of biofouling
agents, corrosion products, and silt that may adversely affect the
heat transfer performance of the system.
2. Page 6, paragraph 1. The generic letter does not specifically
address testing of automatic safety features actuation which may be
required to provide the required service water flow to safety-
related heat exchangers. Does the NRC have any recommendations on
functional tests of systems? (Portland General Electric)
Answer
The generic letter was written with the tacit assumption that all
other regulatory conditions would be observed. In particular,
functional testing required by technical specifications must be
accomplished independently of the recommended actions of the generic
letter. Where there is overlap, credit may be taken for the
functional tests required by the technical specifications. The
procedures, results, and considerations of such tests should be
documented with the response to the generic letter and retained in
appropriate plant records.
3. Recommended Action II paragraph 4 states tests should be performed
following corrective action. Would bulleting tubes be considered as
corrective actions? (Unidentified)
Answer
Yes.
4. Generic Letter 89-13 states that tests should be performed on heat
ex changers before and after "corrective action" is performed. What
is meant by "corrective action"? (Southern California Edison)
Answer
Corrective action is any action that improves the condition of the
heat exchanger.
.Generic Letter 89-13 -34-
Supplement 1
IV. ACTION III - ROUTINE INSPECTION AND MAINTENANCE
A. Recommendation III states, "Ensure by establishing a routine
inspection and maintenance program . . . that corrosion, erosion . .
. cannot degrade the performance of the safety-related systems
supplied by service water." [Emphasis added.] It would seem
unrealistic to assume that a program could be developed that will
ensure absolutely no degradation of the system. Could you clarify
that the intent here is to establish a program which will ensure
that the system cannot degrade to the point at which its ability to
perform its safety function is impaired? (Duke Power)
Answer
The NRC staff concurs in this interpretation.
B. Must all safety-related service water piping be cleaned or only the
piping that is susceptible to corrosion buildup, i.e., low flow
areas? Nondestructive examinations would be used to confirm the
areas needed to be cleaned. (Wisconsin Public Service)
Answer
Recommended Action III is intended to provide assurance that the
performance of open-cycle service water piping and components is not
degraded as a result of corrosion, erosion, protective coating
failure, silting, and biofouling. Once this assurance is made, the
routine maintenance and inspection program can concentrate on those
piping segments that are susceptible to these problems.
C. Would it be considered acceptable to omit from inspection piping
which is practically inaccessible (i.e., underground piping) based
on inspections of practically accessible piping? (Philadelphia
Electric)
Answer
Inaccessibility itself would not be a sufficient reason for not
inspecting piping. However, if additional justification including
operational data and prior history is available, along with an
evaluation that clearly shows that inspections would not be
necessary, then inspection could be omitted.
D. Refer to Item III. Does the maintenance program have to include
sampling of any crud or sediment found to determine its source;
e.g., during routine maintenance a small amount of sediment was
cleaned from a heat exchanger and the only documentation stated that
it appeared to be a normal corrosion deposit? (Niagara Mohawk
Power)
.Generic Letter 89-13 -35-
Supplement 1
Answer
If the maintenance program can ensure that the heat removal
requirements for the service water system are met, then it is
acceptable. The better the root cause analysis of a problem is,
however, the more effective will be the corrective action.
E. Refer to Item III. If minimum fouling is found during maintenance
it should be acceptable to assume that the heat exchanger can still
perform to the original design specification. Does the NRC have a
problem with this assumption? (Niagara Mohawk Power)
Answer
The NRC staff cannot judge the adequacy of heat transfer capability
based on the broad statement of "minimum" fouling. The licensee or
applicant must determine what fouling level requires corrective
action and justify the approach taken.
F. Under Specific Action III(A) on page 6 of the GL, what constitutes
excessive accumulations of biofouling agents, corrosion products,
and silt? (Nuclear Utility Backfit Action Reform Group [NUBARG])
Answer
The staff does not have a quantitative criterion for this parameter.
If such accumulations degrade the heat transfer capability of the
system such that the system cannot perform its safety-related
function as shown by performance trend data, then such accumulations
are excessive.
G. Are plant work requests adequate relevant documentation to support
the inspection and maintenance documentation requirement of Specific
Action III? (NUBARG)
Answer
Yes, as long as they can be made available to an NRC inspector.
H. Programs acceptable to the NRC in response to GL 89-13 Actions I and
II were identified. What are some examples of acceptable inspection
and maintenance programs in response to Action III? (Commonwealth
Edison)
Answer
The NRC has not defined an acceptable program for Action III.
However, the generic letter is designed to give the licensee or
applicant sufficient flexibility in developing an appropriate
program.
.Generic Letter 89-13 -36-
Supplement 1
V. ACTION IV - SINGLE-FAILURE WALKDOWN
A. To what extent does this walkdown have to be performed? We are
presently conducting a design-basis documentation reconstitution
effort. A system walkdown is performed only if a problem is
identified during documentation review. Walkdowns are not conducted
all the time and are not full scope. Is the intent to complete
walkdowns as required to ensure the system meets the licensing basis
for the plant or to verify the as-built condition? (Public Service
Electric and Gas)
Answer
The intent of the recommended action is to verify that the as-built
condition of the system is sufficient to ensure performance of the
intend ed function of the service water system. A design-basis
reconstitution suffices for the walkdown inspection recommended
here.
B. A service water system walkdown inspection was completed in 1986 at
our plant. Can we take credit for that effort for this action or
must we repeat it now to meet the 2-year criterion? (Niagara Mohawk
Power)
Answer
You may take credit for the 1986 walkdown to meet this recommended
action. The suggested time of 2 years to qualify the word "recent"
was not meant to be rigidly interpreted. The NRC is interested in
the walkdown being done now or recently, not in the distant past.
C. Does the system walkdown take into account piping, valves, and in-
line components? What about cabling walkdown? Is our 79-14
walkdown sufficient to address this? (Wisconsin Public Service)
Answer
The system walkdown should ensure that the system's safety-related
function can be accomplished in the event of failure of a single
active component. Cabling walkdowns are thus not in the scope of
Generic Letter 89-13. The intent of Recommended Action IV is to
make maximum use of other pertinent activities in reviewing the
system, but it is not sufficient to depend on 10-year-old reviews to
ascertain the condition of the system today. However, the staff
understands that Bulletin 79-14, "Seismic Analyses for As-Built
Safety-Related Piping Systems," is not closed at all plants;
therefore, if the walkdowns have been done recently, they would be
acceptable. Activities included in the Individual Plant Examination
(IPE) program may also constitute an acceptable response to this
recommended action.
D. Recommendation No. IV discusses system walkdown inspections. GPU
Nuclear assumes that the intent of the walkdown is down to the level
of the flow diagram only. Does the NRC agree with this assumption
or do we intend for a more detailed walkdown? (GPU Nuclear)
.Generic Letter 89-13 -37-
Supplement 1
Answer
See the answer to the previous question. Single-failure
inadequacies can occur in control systems as well as equipment in
which water flows. The staff notes that single-failure inadequacies
have been found at some plants apart from routine surveillance
procedures.
E. Page 6, paragraph IV. Are there any specific requirements which are
new that should be added into existing single-failure analysis?
Explain what is meant by "reconstitution of the design basis of the
system is not intended." (Portland General Electric)
Answer
As discussed in the answers to the next two questions, the staff
does not intend that the licensing basis of a given plant be
changed. Recommended Action IV for single-failure walkdown was not
designed to incorporate any new feature into existing single-
failure analysis techniques. The phrase "reconstitution of the
design basis of the system is not intended" refers to excessively
difficult determinations of design data. For example, this may be
the case for small skid-mounted heat exchangers that were purchased
as piece parts of larger units of equipment and for which the vendor
may not have provided design data to the licensee or applicant. It
would be enough to demonstrate that the equipment module of which
the heat exchanger is a part could do its job.
F. Please elaborate on the requirements of Item 4. Specifically, what
is intended by confirmation of the performance of the service water
system in accordance with the design basis, without a reconstitution
of the design basis? Also, is it intended by this requirement to
perform a complete single-failure analysis of the service water
system? (Northeast Utilities)
Answer
The licensee or applicant is expected to confirm that the installed
as-built system satisfies the design requirements stated in the
plant's licensing basis, that is, the final safety analysis report
(FSAR), the technical specifications, and licensing documentation.
See the answers to Questions V.C and V.D.
G. The generic letter states that the licensee should verify that the
service water system is in accordance with the licensing basis of
the plant. Is the licensing basis, in the context of this generic
letter, considered to be the FSAR and tech specs [technical
specifications] or will a more expansive interpretation be used?
(Wisconsin Electric Power)
Answer
The licensing basis is as defined in the FSAR, technical
specifications, and other licensing documentation. It is not the
staff's intent that the licensing basis be redefined when addressing
Generic Letter 89-13.
.Generic Letter 89-13 -38-
Supplement 1
H. With regard to Action IV which requests confirmation that the
service water system will perform its intended function in
accordance with the licensing basis for the plant, which specific
licensing basis must be reconfirmed at this time? Only the single
active failure review? (Commonwealth Edison)
Answer
The licensing basis is considered to include the FSAR, technical
specifications, and licensing documentation. See the answers to the
previous two questions.
I. Action item 4 of GL 89-13 states that system walkdown inspections
are required to confirm the as-built configuration of the service
water systems. As a recently licensed plant, we are confident that
our configuration control program satisfies this requirement. We
believe system walkdowns are unnecessary for STPEGS [South Texas
Project Electric Generating Station]. (Houston Lighting and Power)
Answer
This position appears to be reasonable for good cause. Ongoing
programs that contain results pertinent to Generic Letter 89-13
should be referenced in the response as justification for an equally
effective program and retained in appropriate plant records.
J. If other design-related issues are being addressed by other
regulatory actions is it acceptable to exclude them from the scope
of review for Action IV? (Commonwealth Edison)
Answer
Yes. See the answer to the previous question.
K. Should the single-failure analysis of the SW system include motive
power (electrical/pneumatic, etc.) to active components (motor,
valve, etc.)? If so, should it be limited only to the delivery of
the motive power to the component, and not the single-failure
reliability of the motive power sources (i.e., do not need to do
single-failure analysis on motive power system)? (Carolina Power
and Light)
Answer
The licensee or applicant should consider single failures in power-
operated equipment or components that are part of the service water
system. Single failures in power supply systems themselves do not
need to be considered under Generic Letter 89-13.
.Generic Letter 89-13 -39-
Supplement 1
VI. ACTION V - PROCEDURES REVIEW
A. Please discuss what constitutes the desired response for Action Item
5. (Confirming the adequacy of maintenance practices, operating and
emergency procedures, and training that involves the service water
system). The letter states that the confirmation "should include"
recent reviews of practices, procedures, and training modules.
Please provide some guidance for performing an adequate review.
Also, are there other actions which the NRC recommends as part of
the confirmation? (South Carolina Electric and Gas)
Answer
The staff has no specific guidance on what procedures, training, and
maintenance practices should be evaluated or revised. The intent of
this item is to increase personnel awareness of the importance of
the service water system with the aim of reducing human errors.
Refer to the wording in Action Item V in Generic Letter 89-13.
Personnel or procedural errors were identified in the Office for
Analysis and Evaluation of Operational Data (AEOD) case study
(NUREG-1275, Volume 3, November 1988) discussed in the generic
letter as a significant cause of service water system failures and
degradations. One acceptable response would be to review those
maintenance practices, operating and emergency procedures, and
training modules that pertain to the events listed in the appendices
in the AEOD case study.
Page Last Reviewed/Updated Tuesday, March 09, 2021
Page Last Reviewed/Updated Tuesday, March 09, 2021