ML20046A320
| ML20046A320 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 03/27/1992 |
| From: | Casey M, Prater G CAROLINA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20046A307 | List: |
| References | |
| NUDOCS 9307270235 | |
| Download: ML20046A320 (37) | |
Text
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4 FOR IN!0RWl0N ONLL SERVICE WATER SYSTEM I
HYDRAULIC ANALYSIS REPORT j
FOR BRUNE 'ICK STEAM ELECTRIC PLANT UNITS 1 AND 2 Revision 2 i
h PCN G0050A
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Prepared by:
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Date '
I Reviewed by: ' h 3[2,7 fL-
' tui/e Date Approved by:
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i' 93O7270235 930720
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- PDR.ADOCK 05000324 P.
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DISCIPLINE DEGICN VERIFICATION RECORD Page 1 I.
Irstructions to verification Persomel Plant bb
[
(Class A)
Project
_6 60 EOC-Q
[] Seismic (Class 8)
File No.
M OO N /2/~.26~-NEN Level
( ) FP-Q (Cless D)
Docwent No.
Al/A Rev 2-( ) Other Design verification should be done in accordance with ANSI N45.2.11, Section 6, as amended by Regulatory
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Guide 1.64, Rev. 2.
Special Instructions:
_ S C M D C d 7~ IS 35CL'l//c2 bt)A7ER St/ STEM k@RA-uuc hAL)fSIS (htPcW % PLCrc h 2sy M fbd/M WW SAGGlT~r A
Discipline Project Engineer
) Ob lhdfA9 s
II.
Verification Docummtation Applicability Discipline Discipline Mechanical M
Civil structural (3
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Seismic Equip. Qual.
[]
Electrical
[]
Civil Stress
[]
IEC I3 Fire Protection
[]
Environmental Qualification
()
Human Factors
[]
Materials
!]
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Other
[]
Verification Methods Used:
Design Review
[ ] Alternate Calculations
[ ] Qualification Testing Design Docwent Acc table: Yes
[
- corrnents attached.
/
Design Verifier. W [M 3!'E7[Y2-A,-
Date i
/
V i
Acknowledgeme o Vprif ka i (DPE)
- Y Nl,' AA Date 3
V y
7 III. Resolution of ts:
k3fil, 2-Comments R olved (Se Att ed):
(RE)
~Y M r ' J^
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b W
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Amice tam m # s s
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Date t
ie:
Des,,, Ve,1f te, f v.i, oocwenFAce,
- 2 74z-Date b2~
b Date d
(DPE) i l
l Proc. 3.3 Re.v. 38 c
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Page 2-
'l DISCIPLINE DES!CM VERIFICATI0W RECIIRD COMMENT SHEET Plant Project h0N(,
N00fd 2/"M" 3
File No.
1 Document ho.
Al/4 Rev [
%cwMTM
- VIC W G S7EAA VD124LALic.
ALYSIS W
This sheet is only recuired when corpents are being made.
Cement gegogy,o No.
Coment Resolution initial /Date C
Proc. 3.3 Rev. 40
COMMENT SHEET SERVICE WATER SYSTEM HYDRAULIC ANALYSIS REPORT, REV.2 Comment Comment Resolution Resolved No.
Ipitial/Date 3)2/2' C
7 1.
Add missing revision margin bars hig
/
on p. I-1; III-7,8,15; Att. 1.p.1; f
2.
Add " implemented by TSI 90-03" in b'DE.D
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Par. I.C 3.
Add " required by TS 3.7.1.2" in hpg 7!
Par. I.H 4.
Clarify Valves throttle "on
@$6.3 accident signals" on P.
I-3 5.
P.
III-10,15: Clarify that Lube
/
87 2-Water is assumed in the analysis y'/56D but is not required in first ten minutes.
f 6.
P.
III-ll: Replace "to minimal v/5ED Y
values" with "sufficiently" kS
" wi NS P o r I/27/f2'
/
8.
P.
III-12, par. 6: Address max.
pressure drop across traveling hD6D MCE-A f
/
screens 9.
P. III-17, Replace " Standing Instruction 89-53" with TSI
/%
90-03" q,
10.
Section V, Replace Hurricane"
'j gytSQ with " Extreme Low Water"
'),
5/Mk c
11.
- 9. V-5, Add reference to gpgp hydraulic analyses for detailed g
explanations s,
12.
Section V.1: Add discussion of MDED 2I basis pump bay water level for Minimum SW Pump Flow h /DN'g
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f I/2 2- '
13.
P. V-7, Clarify why lube water g
and RHR pump room cooler are assumed 4
14 P. V-21,22: " Operator action
/
87 8- '
allowed - see change 16" should M
he " change 4" l4 C
15.
P. V-33: After " conventional k pgp header" add "depressurized" a
f 16.
Correct dates and PM numbers as
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marked in Att. 1
/
i
" 3/37jqp '
17.
Correct misc. typos as marked bEEE472GD 4
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DESIGN REVIEW CHECK SHEET Plant Document Type M
5cevicc WarER SYSTE-H Project SOOC Document 430. /M38Auttc MD/5/5 Re-W File No.
dDOC #/7)E ' A Revision
==
Description:==
Mark each item yes, no, or not applicable and initial each item checked by you.
- 1. Were the inputs correctly selected and incorporated into design?
e G
- 2. Are assumptions used in the design adequately described and reasonable?
4 ll NOTE: Review shall include but is not limited to applicable inputs specified in NED Procedure 3.1. A. paragraph 3.1. A.4
- 3. Are the appropriate quality and quality assurance requirements specified?
- 4. Are applicable codes, standards, and regulatory requirements including issue and addendum properly identified, and are their requirements for design met?
- 3. Has applicable construction and opercting experience been considered?
- 6. Have design interface requirements been satisfied?
I
- 7. Was an appropriate' design method used?
- 8. Is the output reasonable compared to inputs?
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- 9. Are the specified parts, equipment, and processes suitable for the application?
- 10. Are the specified materials compatibiq with each other and.the design environmental conditions to which the materials will be exposed?
/
S SYSWA4 NYDR/WLIC-M e1LYS/S Document Type -
7 Document No.
A//4 Revision 2
11.
e ate maintenance features and requirements been
- 12. Are accessibility and other provisions adequate for performance of maintenance, repair, and any expected in service inspections?
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0
- 13. Has the design properly considered radiation exposure to the public and to plant personnel (ALARA)?
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14 Are acceptance criteria in the design documents sufficient to allow verification that design requirements have been satisfactorily accomplished?
- 15. Have adequate preoperational and periodic test requirements been specified?
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- 16. Ate adequate storing, handling, cleaning, shipping, and identifica n
requirements specified?
- 17. Are requirements for record preparation, review, approval, retentioq etc., adequately specified?
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- 18. Have all problems with this design known from prior application been considered and resolved?
For each question on the check list not answered yes, explain below.
If "Not Applicable
- give reason.
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'Signafbre /
fate (Desigh Ve ifier)
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TABLE OF CONTENTS
'Section' Page Title Page i
Table of Contents ii I.
Executive Summary I-l II.
Introduction 11-1 III.
Design Basis Events and Event Combinations III 1-A.
Summary B.
Identification of Events C.
Service Water System Functional Requirements D.
Bounding System Parameters E.
Design Analysis Cases 1.
Summary 2.
System / Component Requirements and Limitations 3.
Specific Limiting Events F.
Off-Normal. Operations IV.
Single Failure Analysis IV-1 V.
Hydraulic Design Analysis V-1 A.
Model Development and Backgrottnd B.
Analyses and Results C.
Conclusions VI.
Service Water System Setpoint Review VI-l - Design Documents
. - Action Items List I
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11 (4611NED.WP/che)
I, Executive Summarv The Service Water systems at BSEP have been analyzed for hydraulic performance under all plant operating and design basis events.
Specific results of the analyses are presented in this report.
In summary, the
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BSEP Units 1 and 2 Service Water Systems are currently capable of meeting all design hydraulic requirements, subject'to the following limitations:
A.
One RHR pump room cooler must remain in service'when the NSW header is in service to ensure minimun SW puanp flow requirements are satisfied. This restriction has been implemented by Technical Specification Interpretation No. 90-03,.Rev. O.
H B.
When either unit is in shutdown, maximum RBCCW and RHR SW flows for that unit must be. limited as follows:
i 1.
With two NSW pumps operable, 5500 gpm and 4500 gpm, respectively.
2.
With one NSW pump operable, 4000 gpm and 2800 gpm, respectively.
These restrictions have been implemented by Technical j
Specification Interpretation No. 90-03, Rev. O.
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These flow restrictions apply to normal system configurations.
Abnormal system lineups may have diff erent operating flow limits and are controlled by specific documents (TSI's, EER's, etc.)
relating to the abnormal lineup.
i C.
Vital Header operation with service water supply f rom the CSW header is an abnormal SW system operating lineup.
When operating in this lineup, Valves SW-V101, SW-V103, and SW V106 must be epen.
with power removed. Also, the Vital Header must be positively isolated from the NSW Header (either Valve SW V116 closed or Valve-l SW-V117 closed'with power removed).
These restrictions are defined in EER-89-0333, Rev. O, and EER-89-0263, Rev, 0, and are implemented by TSI 90-03, Rev. 0 l
r D.
Cross-header leakage must be limited to the values assumed in;the 1
analyses.
Limits for cross-header leakage are given in
-l Calculations C0050A-10 and C0050A-12.
I-1 (4611NED.WP/che)
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3 E,
Minimum RBCCW flow rates must be maintained as follows:
1.
With two NSW pumps operable, 2500 gpm.
2.
With only on,
- r. W pump capable of operation, no minimum limit applies.
The 2500 gpm limit has been implemented by Technical Specification Interpretation No. 90 03, Rev. O.
l F.
During normal operation, RBCCW flow must not exceed its. design ilow of 7200 gpm. This restriction has been implemented by Technical Specification Interpretation No. 90-03 Rev. O.
n C.
During extreme low water level conditions, the following restrictions must be observed:
1.
Plant shutdown at a SW pump bay water level of 6.0-ft.-MSL' or lower.
2.
Maintain a pressure of at least 62 psig (Unit 1) or 59 psig-(Unit 2) in the NSW header, and observe the maximum allowable shutdown flow rates for RBCCW and RHR SW if those,
r flow rates allow an NSW header pressure-greater than the stated value to be maintained.
If NSW header pressure cannot be-maintained as required, reduce RBCCW and/or PER SW flows as needed to. increase header pressure. With only one NSW' pump capable of operation, no minimum RBCCW flow limit.
l is required (see I.E.2 above).
I 3.
The SW Lube Water systems must not be cross-tied.
Each unit' must supply its own Lube Water. header.
H.
If a unit in shutdown has less than one NSW pump operable, the
' i other unit must have both NSW pumps operable. This is required by Technical Specification No. 3.7.1.2.
This report assumes implementation of PMs89-088 (Unit 1) and 89-089 (Unit 2), which-add LOOP closure logic circuits to Valves SW-V103 and SW-V106.
This report also assumes implementation of Pms 90 008-(Unit l')
and 90-009 (Unit 2), which add low CSW header pressure throttling logic to Valves SW-V3 and SW-V4.
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Future plans.for the SW systems involve installation of additional plant modifications to reduce the number of operating restrictions currently imposed.
In particular, upgraded NSW pump motor thrust bearings will be
-installed. The new thrust bearings will be sized for the thrust load at I
zero: flow and will eliminate the requirements for minimum RBCCW flow rate and'one RIIR pump room cooler in service.
This will also minimize.
the restrictions on maximum allowable RBCCW and R11R SW flow rates since full closure of Valves SW-V103 and SW-V106 (which presently are throttled on accident signals) will be possible, f
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II, Introduction i
The Service Water system hydraulic analysis effort was initiated in
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March 1989 in response to concerns raised by the NRC Diagnostic Evaluation Team (DET) about the Service Water system design performance capability.
A computer-based hydraulic network analysis program (KYPIPE) was selected as the most effective meth'od of evaluating Service Water system design capability over the full range of design basis events.
The safety-related sections of the Unit 2 Service Water-system associated with the nuclear Service Water header were first modeled with~
the KYPIPE program and then calibrated against actual field test data for Unit 2.
The calibrated model is used to simulate performance of the nuclear header portion of the Unit 2 Service Water system for various
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operating conditions and design basis events.
Performance of the conventional header portion of the Service Water system is bounded by the nuclear header model based on similarity of components and piping layout in the field.
This assumption has been verified by testing Unit 2 vital header performance when supplied by the CSW header and assessing CSW header capability to supply RHR SW in comparison to the NSW header.
t The KYPIPE computer model has been used to evaluate various aspects of Service Water system performance and design capability.
As each particular concern was investigated and resolved, engineering evaluation reports (EERs) and/or design calculations were issued to fully document the resultant Service Water system design capabilities and the bases supporting the analyses.
This individual treatment.of each particular design concern ensured a clear, ongoing understanding of SW system design capability and provided the opportunity for increased focus of resources on any design or operating changes identified as necessary to I
maintain system operability.
However it was recognized that the decision to issue individual documents as discrete items of the hydraulic analysis were completed made it less convenient to quickly
+
comprehend the full hydraulic design basis of the Service Water system.
I Accordingly, an action item was established to create a single document consolidating all hydraulic design basis information and supporting analyses to ensure consistent treatment of Service Water system design issues in the future.
This hydraulic analysis report is the consolidated design document for this project. A comprehensive Service l
Water System DBD is currently under development _and will incorporate appropriate information from this report.
l The hydraulic analysis report is divided into six sections as follows:
I l
11 - 1 G611NED.WP/che)
I l
f I.
Executive Summary II.
Introduction III.
Design Basis Events and Event Combinations The design basis events section is divided into the following subsections:
III.A.
Summary - Several of the key design bases for the Service Water system are listed and briefly discussed.
III.B.
Identification of Events - UFSAR Chapters 15 and 3.1.2 are reviewed to define the events (transients, accidents, etc.) which must be l
considered in the plant design, as well as the appropriate combinations of events which must be postulated.
In addition, events not addressed in these chapters (Appendix R, Station Blackout) l but which are required for plant design are discussed.
III.C.
Service Water System Functional Requirements -
The specific requirements (flow rates, pressures, etc.) the Service Water system must meet for the various design basis events are defined.
III.D.
Bounding System Parameters - Limiting system and/or component parameters (temperature, cooling water, etc.) and their effects on Service Water system performance are defined.
III.E.
Design Analysis Cases - The design basis events which are the most limiting for the Service Water system and the supporting bases-for.their selection are evaluated.
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III.F.
Off-Normal Operations.- The effects on Service Water system performance and design capability of off normal operating lineups'are reviewed.
- l II - 2 (4611NED.WP/che)
.,i IV, Single Failure Analysis A comprehensive analysis of potential single failures and their resultant impact on the Service. Water system (Calculation G0050A-16) is incorporated in this report asSection IV.
The full.
scope of the single failure requirement with respect to'the BSEP-Service Water systems is defined.
Those. single failures considered most limiting are identified and pertinent bases discussed.
V.
Hydraulic Design Analyses Specific results of the limiting design basis analyses are
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presented and discussed. Assumptions incorporated into the-analyses are listed. Any operating and/or-design limitations on the Service Water system are-explained, as well as any impacts to l
other plant systems or procedures.
A brief review of the evolution of the current computer models for the Service Water systems is included, also.
VI.
Service Water System Serpoint Review i
All Service Water system setpoints are reviewed and evaluated against the final Service Water system design bases and performance parameters' This review was issued as Calculation t
C0050A 18 and.is incorporated in this report asSection VI.
Current setpoints are verified to be acceptable Enhancements to existing setpoints are identified.
Two attachments are included as part of the Hydraulic Report.
The first provides a listing of documents issued to date or' planned in support of this SW project. The second provides a list.of action items generated as a result of this hydraulic report.
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s III.
Desien Basis Events and Event Combinations r
A.
Summarv f
The Service Water System Hydraulic Analysis Report documents the capabilities of the BSEP Units 1 and 2 Service. Water systems to perform their safety-related functions under all design conditions.
To fully evaluate the system capabilities, a complete i
analysis of the design bases for the BSEP Service Water systems was required.
A summary of the key design bases is provided below-
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1.
The Service Water system must be.designedfto withstand a single active failure.
Both mechanical and electrical active failures must be considered.
Check valves are classified as passive components in the-original BSEP licensing basis, but are analyzed as active failures in
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accordance with current industry practice.
l 2.
The Service Water System must be designed to withstand a single passive electrical failure.
Passive mechanical.
j failures are addressed by the seismic design of essential SW,
system piping and components and by the capability to t
isolate nonsafety-related portions of the SW system.
l r
3.
Natural phenomena - including hurricanes, floods, and l
earthquakes - must be considered in the design basis of the f
plant.
Natural phenomena must be considered coincident with' appropriate combinations of other events.
l The mast severe impact of the design basis natural phenomena on Service Water system hydraulic performance is caused by j
resultant variations in the intake canal water-level. As stated in UFSAR Section 2.4.8.4, the Service Water system is l
designed to function during the~ design basis. flood and low
~i 1
water conditions caused by the worst reasonably possible=
hurricane storm conditions.
BSEP procedures require plant shutdown for hurricanes and floods. Therefore, the-appropriate events required to be evaluated coincident with hurricanes and floods are only those' events considered credible during shutdown conditions.
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(4611NED.WP/che) 1
4.
Plant structures and systems at BSEP designated as Seismic Class I have been designed to withstand the effects of the design basis natural phenomena without loss of the capability to perf orm their safety-related functions.
UFSAR Chapters 2 and 3 discuss in detail the design requirements for such events as the Probable Maximum Hurricane (PMH), the Design Basis Earthquake (DBE), and the Probable Maximum Flood (PMF).
L 5.
Loss of offsite power (LOOP) must be considered coincident with all design basis events if the LOOP results in a greater challenge to plant safety.
The loss of offsite power (LOOP) for one unit only has been. evaluated and the consequences are bounded by a site-wide LOOP.
6.
Loss-of-coolant accidents (LOCA) are credible only in Modes 1, 2, and 3 since the reactor coolant piping is significantly pressurized only during these modes.
- However, a LOCA signal without an actual pipe break must be postulated in Modes 4 and 5 because the ECCS initiation instrumentation and logic must be in operation in accordance with Technical Specifications and an operator error or instrumentation failure could generate the LOCA signal.
7.
RHR Service Water system operation in support of testing during Modes 1, 2, and 3 is not evaluated as an initial state from which a design basis event can occur.
This position is based on the following:
The basis for this position is developed from the Technical Specification requirements for equipment out-of-service.
Risks to plant safety associated with equipment out-of-service t!.mes have been evaluated and accepted in the Technical Specifications provided the out of-service restrictions associated with the particular equipment or safety systems are observed.
Original' Technical Specifications, as well as subsequent Technical
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Specification interpretations, permit one service water pump to be out-of-service up to seven days without other
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compensatory measures, During this time, the single failure is the pump out-of-service.
Operation of both RHR SW pumps represents no more flow diversion than the equivalent of one service water pump.
Since RHR SW system operation in HI - 2 (4611NED.WP/che)
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h Modes 1, 2, and 3 lasts only.a few hours,_the risk is well bounded by existing Technical Specifications. Also, j
operation for testing purposes reduces-future risk by identifying failures or system performance deterioration, thus offsetting the.small risk associated with RHR SW t
testing in Modes 1,2,and 3.
j l
To.further ensure this assumption is not invalidated TSI 89-02 limiting the out-of service time of the RHR SW pumps to less than seven days has been implemented, j
8.
Operator action-to mitigate adverse Servic'e Water system response cannot be credited during the first ten minutes of j
a design basis event.
Operator action may be taken after ten minutes subject to specific plant conditions. These restrictions on operator action apply to the nonevent unit-as well as the event unit.
l
,i 9.
The maximum service water inlet temperature is 90*F.
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10.
The Appendix R and Station Blackout design events and the.
" Shutdown from Outside the Control Room" event defined.in UFSAR Chapter 15 (Event 38) do not require consideration'of ~
a coincident single active failure.
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11.
The Reactor Building is inaccessible for operator action-at all times following a high energy line break ~(LOCA outside-primary containment).
12.
Diesel generator jacket water cooling and service water pump
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lube water are the only required service water loads in-the first ten minutes of an event.
r 13.
The single active failure required coincident with a design-basis event must be evaluated as occurring on the nonevent!
unit if such an assumption makes the event more severe with-respect to plant safety.
14.
UFSAR Section 15.0A.2.7 states the single failure I
" requirement is not applicable during system repair if the availability of the safety action is maintained either'by restricting the allowable repair time or by more frequently testing' redundant system."
The Technical Specifications III - 3 (4611NED.WP/che)
H
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provide such ' guidance whenever: an essential safety-related L component is declared inoperable. Accordingly, single failures of safety-related systems or components are not considered credible whenever the redundant system or component is taken out of service in accordance~with the plant Technical Specifications, t
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These design bases are discussed in greater detail in the following hydraulic report.
In addition, the bounding assumptions and limiting parameters associated with plant and component
[
conditions are evaluated and incorporated into the specific system design analyses.
B.
Identification of Events 1
1.
UFSAR Chapter 15 Events Chapter 15 of the UFSAR defines and analyzes those events which have the potential to adversely impact nuclear safety.
or create an undue hazard to the health and safety of the-general public.
These events are classified as design basis i
events. The analyses in Chapter 15 establish the operational limitationi and the specific safety-related plant systems required to guarantee the consequences of the design basis events remain within previously defined limits of acceptability.
1 Appendix.15.0A of the UFSAR discusses the approach to nuclear safety used in Chapter 15 and defines the rules for event analysis.
In addition, the safety related' systems necessary to mitigate the consequences of an event and the-specific plant operating. modes in which the systems are required are defined. Auxiliary plant-systems which are needed'to support the required safety-related systems are i
also addressed and are shown on " commonality" drawings which l
define the exact events and operating. states in which the auxiliary system isirequired. The commonality chart for.the l
~
Service Water system is' Figure 15.0A.6-29,
- i As noted in Appendix 15.0A, this appendix was part of the original FSAR and is. included.in the UFSAR for completeness.
It is not updated to incorporate the latest analyses or
{
plant modifications, and so cannot be considered accurate I
!!! - 4 (4611NED.WP/che) 5 4., +
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without additional investigation. Review of the detailed discussions in the other sections of UFSAR Chapter 15 verified as correct the information and assumptions concerning the Service Water system contained in Appendix 15.0A, with the one exception that the Service Water system is not used to support operation of Control Room HVAC as indicated in Figure 15;0.A.6-29.
The design basis events in Chapter 15 are grouped into four categories:
planned operations, abnormal operating transients., accidents, and special events.
Each event is further defined by the plant operating modes in which occurrence of the specific event can be considered credible, Planned Operations a.
1 Planned operations are those events which are considered to be normal plant operations conducted in the absence of significant abnormalities.
Nuclear safety criteria are' satisfied principally by placing restrictions on.certain process parameters within normally operating systems. Other design basis events are considered to be initiated from' planned operating states.
b.
Abnormal Operational Transients Abnormal operational transients are those transients which j
can be reasonably expected to occur during-any plant j
operating mode and~ which threaten the integrity of the reactor fuel or the nuclear system process barrier.
+
c.
Accidents Accidents are postulated events which affect-one or more radioactive-material barriers and are not expected to occur during plant operations. Accidents typically result in the~
most severe requirements for safety-related systems of-all the design basis events (excluding special events).
?
d.
'Special Events Special events are postulated to demonstrate some special capability of the plant. These events are of very low 111 5
(I.611NED.WP/che)
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t probability and, as such, are not always required to meet the same design assumptions as other events.
2.
UFSAR Chapters 2 and 3 Requirements Chapter 3.1.2 of the UFSAR discusses _BSEP's compliance with the General Design Criteria (GDC).
In particular, two requirements addressed in this chapter impact the analyses of the Service Water system design capability:
natural phenomena and loss of off-site power.
Specific natural-phenomena included in the BSEP Units 1_and 2 design bases are discussed in detail in UFSAR Chapters 2 and 3 and include earthquake, hurricane, and flood events.
UFSAR paragraph 3.1.2.1.2 states safety-related systems, i
structures, and components must be able to withstand the effects of natural phenomena without loss of capability to perform safety functions, including the effects of appropriate _ combinations of normal and accident conditions.
BSEP safety-related systems designated Seismic Class I are seismically designed for the worst case earthquake; therefore, failure of a safety system due'to an earthquake is not credible and need not be considered in combination with other events.
This is also true of the.other design basis natural phenomena and Seismic Class I systems.
The impact of natural phenomena on Service Water system hydraulic capability is found in UFSAR Section 2.4.
Paragraph 2.4.8.4 states the Service Water' system will function under the design basis flood and low water conditions.
Sections 2.4.5, 2.4.10, and 2.4.11 state the extreme canal water levels are caused by the Probable Maximum Hurricane.(extreme
. r low) and Flood (extreme high).
BSEP Procedure AOP-13 requires the plant to be shut down whenever a hurricane or flood is expected to minimize adverse impact on plant safety. Accordingly, those events considered credible only during power operation (specifically, LOCA) need not be taken in conjunction with the occurrence of a hurricane or flood.
10CFR50, Appendix A, Criterion 44, " Cooling Water,"
specifically states a loss of offsite power must be 111 - 6 (I.611NED.WP/che) e w
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considered in. conjunction with other' design basis. events if the LOOP places more severe requirements on operation of the i
safety-related system.
This requirement is supported by UFSAR paragraph 3.1.2.4.6, "ECCS," which specifically states a LOOP must be considered concurrently with the worst case LOCA. Also, UFSAR paragraph 3.1.2.4.15 states a LOOP must' be evaluated assuming a coincident single failure (see Section IV, " Single Failure Analysis," for scope of single l
failure requirements).
3.
Other Requirements l
-i I
In addition to the events described in the UFSAR,-BSEP is committed to designing Units 1 and 2 to withstand the following two events:
Appendix R ac defined in the BSEP. Alternate Shutdown a.
Capability Assessment Report, dated April 1984.
b.
Station Blackout as defined in CP&L letters to NRC, Nos. NLS 89-256 (" Revised Response to Station Blackout Rule") and NLS 89-053 (" Response to Station Blackout Rule").
~
f As with the special events defined in Chapter 15, Appendix R and Station Blackout are considered unique design events which are not necessarily required to meet all the design assumptions applicable to other events.
For example, the documents referenced above specifically exclude consideration of a single failure coincident with these events.
.i The information and references discussed above have been considered in establishing the limiting design conditions for the Service Water System analyses.
C.
Service Water System Functional Recuirements i
The safety-related function of the Service Water system is to o
provide cooling water and/or bearing lubrication flow to all safety-related components-which require service water and^are necessary for safe shutdown of the plant.
This function must be satisfied for the worst case design basis events including all required limiting assumptions (single-failure, loss of off-site.
111 - 7 (4611NED.WP/che)
.I
power, maximum service water inlet temperature, specific plant operating mode, etc.),
j The Service Water systems at the Brunswick units are divided into two subsystems:
the Nuclear Service Water (NSW) header and the Conventional Service Water (CSW) header. The CSW header normally supplies service water to the nonsafety related system loads--
TBCCW, circulating water pumps, and chlorination. The NSW header normally supplies the safety-related loads--vital header, diesel i
generators, and RHR service water--as well as the nonsafety related RBCCW heat exchangers. The CSW header can be aligned to supply service water individually to RBCCW, the vital ceader, and RHR SW if so desired.
In addition, the CSW pumps can be aligned to supply their full flow to the NSW header, Nonsafety 1 cads normally supplied by the CSW header can be isolated by dual safety-related MOVs.to ensure sufficient CSW system flow in the l
event the CSW header is needed to supply safety-related loads.
The Station Blackout event does not require service water to effect a safe shutdown of the plant and is not considered in the design analyses of the Service Water system.
Specific design requirements of the Service Water system with
~
respect to component cooling or lubrication flows are discussed below.
1.
RHR SW Flow - The Service Water system provides service water to the RHR heat exchanger to allow the RHR system to.
cool the reactor core.
The RHR heat exchanger is designed for 8000 gpm service water flow; the RHR SW pumps are sized-f or 4000 gpm each.
However, analyses by the Nuclear. Fuels Section have demonstrated the capability of cooling the reactor core satisfactorily with much less service water flow.
EER 89-0166, Attachment 8, Revision 0, verified 4500 gpm service water flow is sufficient to cool the core assuming 7500 gpm RHR flow and maximum service water inlet temperature (90'F).
Calculation C0050A 11, Revision 0, verified only 2500 gpm service water flow is required in Modes 4 and 5 to maintain the reactor core at less than the 212*F temperature limit for Mode 4 Accordingly, these-values have been used in the final design analyses.
111 8
(4611NED.WP/che) i
i 2.
Diesel Generators - The jacket water coolers of the DGs'are designed for 750 gpm service water flow.
Calculation.
M-89-0008, Revision 0, verified adequate cooling can be
]
provided with only 350 gpm.
This value has been assumed as the limiting flow value.
3.
RHR Pump Room Coolers - The original design service water flow required for the RHR room coolers was 300 gpm per cooler for 90*F service water. This value has been revised by Calculation C0050A-01, Revision 2, which provides a curve of service water flow versus service water temperature for the design heat transfer rate.
With the maximum service ~
water temperature of 90*F and 10% of the room cooler tubes plugged, the required service water flowrate is 186 gpm.
4.
Core Spray Pump Room Coolers - As with the RHR room coolers, the original design service water flow rate has'been revised by calculation (G0050A-02, Revision 2).
This calculation also provides a curve of service water flow versus service water temperature.
For the maximum service water j
temperature of 90*F, the required service water flowrate.is 47 gpm.
5.
RHR Pumps Seal Coolers - The original design service water flow rate for these coolers is 15 gpm per. cooler for 90*F service water.
However, subsequent analyses by GE for seal 5
cooler procurement indicate the pump seal coolers are I
considered "Q"
for pressure boundary integrity only.
Therefore, the seal cooling function required of the Service Water system is considered "non-Q."
This issue is discussed in attachments to Calculations C0050A-10 and G0050A-12 and i
in EER-89-0135, Rev. O, Attachment 10.
s 6.
Service Water Pumps Lube Water - Each service water pump requires 17 gpm (maximum) and 10 gpm (minimum) of cooling l
water for the motor and pump bearings (Reference attachments to Calculations C0050A-10 and C0050A-12).
-l 7.
RHR SW Pumps Motor Coolers - The design service water flow-rate to the motor coolers at a 90*F service water inlet temperature is 38 gpm as stated in Specification 128-004.
1 Ill - 9 (I.611NED.WP/che)
_ _ ~.
~_ _
i 8.
Reactor Building Closed Cooling Water - The RBCCW system is nonsafety-related and is not required during any design-i basis event.
However, to ensure the SW pumps operate _above the minimum required flow and below pump runout during all normal and accident conditions, an RBCCW flow range of 2500 7200 gpm for normal operating conditions with 2 SW pumps capable of operation on the NSW header has been established by the plant and is assumed in these analyses.
The Service Water system also has a design requirement to provide redundant sources of service water to all safety related equipment.
This criterion is satisfied by the design of the nucicar and conventional service water. header subsystems and by the parallel Unit 1 and Unit 2 nuclear header supplies to the i
diesel generators.
The nuclear header is established as the primary source of cooling water during an event, as evidenced by the NSW Pump auto-start on LOOP.and the automatic opening logic of t
the supply valve to the vital header (SW-V1171.
Backup _to the nuclear header can be provided by the conventional header in the time frame when operator action can be credited.
As shown in the hydraulic analysis section of this report, certain design basis e
scenarios must have the CSW header available after the first 10 minutes of an event to ensure a safe shutdown of the plant.
In the early phase of an event when operator action is not assumed, the diesel generators are the'only required system cooling load and backup service water is supplied by.the other l
unit's nuclear header. The assumption that the diesel generators are the only required cooling loads in the first 10 minutes of an event is supported by the Service Water system study attached to BSEP memorandum BSEP/85-0589 dated 5/27/85 (File No. B10-13510).
Service Water Lube Water is assumed to be required in the first 10
)
minutes, but analyses in Calculation C0050A-17 and EER-89-0334 have shown the SW pumps are capable of satisfactory operation without lube water'in the first 10 minutes of an event.
Backup for the SW lube water system after 10 minutes is provided by a cross-connection line to the other unit's lube water header.
D.
Boundine System Parameters-Before the final analyses of Service Water system design capability can be completed, all bounding system parameters and limiting assumptions must be defined.
Required flows are i
!!! - 10 i
(4611NED.WP/che) l
.m
I discussed in the previous section; specific system / component f
limitations and assumptions are discussed below:
1.
Service water inlet temperature - System heat exchanger performance and setpoints such as pump NPSHA must be. based on the maximum expected service water inlet temperature to ensure adequate design capability.
The FSAR lists the service water design temperature range as 33*F - 90*F.
Also, the design specifications for Service Water system components such as heat exchangers lists the maximum design service water inlet temperature as 90*F.
Accordingly, 90*F has been assumed as the design maximum service water inlet-temperature.
2.
Service water pump bay water level - The level of the' water.
in the service water pump bay has a direct effect on the NPSH available for the SW pumps and,_therefore, on the maximum allowable flow rate through the SW pumps. 'The r
Intake Canal Hydraulic Analysis, dated 5-30 89, for the BSEP plant-provides information on canal and pump bay water levels for various system flow rates and tide conditions.
The maximum normal pump bay water level is 2.0 feet.above mean sea level and is taken from the mean high water. level curve for zero gpm total flow.
The minimum normal pump bay level is'6.0 feet below mean sea level and is-based on the i
periodic low water level curve with 1,050,000 gpm total flow (maximum circulating water flow per SD-29) and 50,000 gpm f
service water' flow. The extreme low water level curve provided in the report is not used for normal operation 3
since it is based on-the Probable Maximum Hurricane and plant procedures are in place requiring plant shutdown in the event of a hurricane.
Acceptable Service Water system performance with canal levels below -6.0-feet MSL is ensured by compliance with instructions in BSEP AOP-13 which require circulating water-and service water flows to be reduced sufficiently to maintain Service Water system performance capabilities.
BSEP A0P 13 also contains instructions for shutdown in the event of a flood.
UFSAR Section 2.4.5.2 states the-maximum i
still water 1cvel expected to occur at the BSEP site is-
+22.0 feet mean sea level.
Design analyses conducted with an intake water level of +22.0 feet mean sea level l
111 11 (I.611NED.WP/che) l l
_~
L demonstrate. acceptable Service. Water system performance for all normal and shutdown operating modes..Therefore, no additional design or operating restrictions (such as are required for hurricane conditions) are necessary to ensure Service Water system design capability during flood conditions, n
3.
Service water pump limitations - The original NPSHR curve
'l for the SW pumps was for a typical pump of the same design.
Actual shop testing of one of the BSEP SW pumps during 1989-generated an NPSHR curve specific to the SW pumps installed-at BSEP.
These NPSHR values are contained in the Johnston Pump Company Test Report dated 6-26-89 and have been used in i
the design analyses.
In addition, further vendor review of flow conditions predicted by the Service Water system computer model has resulted in an extension of the allowable maximum flow rates for normal pump bay levels (Johnston Pump Company letter dated 9-1-89, File No. BC0050A-AA-A500) and for flood bay levels (telecon with Johnston Pump Company dated 11-1-89, File No. BC0050A-DE-AS43).
4.
Service water pump motor limitations - The service water pump motor thrust bearing load carrying capability was evaluated against SW pump flow and the asso:iated thrust on the bearing.
Based on this review and actual thrust bearing tests documented in the Johnston Pump Company service water pump test report dated 6-26-89, a minimum alicvable SW pump flow rate of 1500 gpm was established'. An additional, on*
site thrust bearing test was performed in December 1989 to finalize thrust bearing capability. After reviewing the test results, CE recommended a thrust bearing upgrade to allow pump operation at zero flow. The new bearings' will be r
installed on the NSWP motors and will allow the 1500 gpm minimum flow requirement to be discontinued.
3.
Required component flow rates - Cooling and/or lubricating water flow rates for the safety-related components supplied by service water are discussed in-Section III.C.of this
- report, i
6.
Screen / strainer DPs - The pressure drops over screening components connected with the Service Water system were reviewed for impact on SW system design capability. The III - 12 (4611NED.WP/che)
t fish diversion structure and normal traveling creen pressure drops were incorporated in the Intake Canal liydraulic Analysis. Maximum screen pressure drops have been considered in the determination of pump bay water levels.
The service water pump discharge strainer is safety-related j
and has a control logic which initiates backwashing of the
+
strainer when the DP reaches 4 psid 1 0.5 psi.
Accordingly, the maximum strainer DP can be 4.5 psid assuming proper functioning of the backwash system. This value has been used in all the minimum pump and cooling flow design analyses since it restricts system flow more than a lower-DP.
For maximum pump flow scenarios, a minimum strainer DP of 1.0 psid is assumed. This lower strainer DP is more limiting than a higher DP since it provides less restriction to system flow and greater possibility of pump runout.
7.
Service water pump performance - The SW pump testing performed by Johnston Pump Company showed the SW pump l
performance (measured by TDH for a given flow) had decreased by approximately 9 percent from the original design pump curve. This decrease in pump performance is also supported l
by testing at the BSEP site performed during 1989 (Procs. 2-SP-89-021 and 1-SP-89-027).
This' reduced SW pump performance curve has been incorporated into the hydraulic model.
8.
System cross-header leakage - Service Water system flow testing performed under Special Procedures Nos. 2-SP 89-021 and 1-SP-89-027 showed service water was being lost from the NSW header to the CSW header through the various cross tie valves in the system.
The leakage data was used to extrapolate an effective " resistance-to-leakage" K factor at higher header DPs (such as would exist during a design basis event).
This K factor was then modeled into the hydraulic model-as a single " leakage" line which'would represent flow lost to the CSW header under various NSW header operating conditions. -Based on applicable test data, Unit 2 leakage flow at a header DP of 40 psid is calculated to be approximately 1820 gpm; Unit 1 leakage flow at the same header DP is calculated to be approximately half that of Unit 2.
l 111 - 13 (4611NED.VP/che)
)
.,~s.
-~
i l
L I
During the BSE: Unit 2 1989 Refueling Outage, Plant Modifications'PM-218R, S, and T were implemented to replace the cross connection valves between.the CSW pumps and the NSW header with new valves to reduce cross-tie leakage.
Acceptance testing for these modifications verified cross-j tie leakage had been reduced to a value significantly less than the Unit 1 leakage value calculated previously.
{
However, in order to provide margin for future valve wear and leakage, the original Unit 1 leakage value is used in f
all SW system analyses.
Periodic testing (PT-24.6.4 for both units) is performed to ensure this leakage assumption l
is still bounding.
9.
Equipment availability - Equipment being tracked under an' f
active LCO is assumed to be the single active failure which must be taken. This position is supported by statements in UFSAR Section 15.0A.2.7 and is reasonable given the short out-of-service times allowed for the equipment and/or the increased testing frequency for the associated redundant-component or safety train.
E.
Design Analysis Cases The design bases and bounding system parameters are combined as
[
appropriate to generate the limiting design bases events for
~
service water system operation.
Then these events are simulated using the KYPIPE model and the results are compared to the required system outputs.
Below is a summary of the specific design events and limiting assumptions considered to be'the most f
challenging to Service Water system design capability.
l 1.
Time Frames for Event Analyses.
I As stated earlier, the general safety-related function of the Service Water system is to provide sufficient cooling water flow to safety related components during all normal l
operating'and design basis events. The design basis events.
l chosen for detailed ~ analysis must represent the most. severe l
challenges to the capability of the SW system to satisfy this requirement and must include the effects of the most i
limiting set of. credible assumptions such as single' failure, LOOP, operator action, etc.
111 - 14 (4611NED.WP/che) 1 e
r
,r--,w.----
s s.,
For the purpose of system analysis, the response of the Service Water system to any design basis event has been separated into two time frames:
the time during which operator action cannot be credited (the 0 10 minute phase of the event) and the time after which operator action can be assumed subject to specific plant conditions (the after 10 minute phase).
Since operator action cannot be credited in the first 10 minutes, Service Water system design must be such that the safety limits of key components (specifically, the NSW pumps) are not exceeded, resulting in unavailability of the SW system for the long term.
In the 0-10' minute phase, the SW system must provide sufficient cooling flow to the diesel generators and lube water (the only cooling loads in the first 10 minutes) and must maintain system / component capability to function following the initial 10 minutes of the event.
In the after 10 minute phase of an event, the SW system must provide the required service water flow for component cooling while meeting all equipment. operability limits.
2.
System / Component Requirements and Limitations In the first 10 minutes of an event, the.only components
~
evaluated as being subject to damage are the service water pumps.
The diese1' generators do require cooling, but system testing and analysis results show adequate cooling during the first 10 minutes is ensured so long as the SW pumps continue to operate.
The potential damage to the SW pumps could be caused by either excessive or insufficient flows through the pumps.
Since operator action cannot be assumed in the first 10 minutes, flow paths cannot be opened or-isolated to change SW pump flow. When coupled with additional required assumptions single failure, etc. - the potential for pump damage due to runcut or low flow operation becomes significant.
In the after 10 minute phase,.the Service Water system must supply adequate cooling to all required components while satisfying equipment operability limits.
In this scenario, the main limiting parameter is RHR SW pump suction pressure, To ensure adequate shutdown capability for the-plant following an event, the SW system must be abic to deliver the required minimum flow to the RHR heat exchanger while
!!! - 15 (4611NED.WP/che)
I r
-r.-
w v
maintaining the RHR SW pump suction pressure above the low
~
pressure trip setpoint. This ensures adequate RER SW pump NPSH. At the same time, the SW system must be capable.of supplying adequate cooling flow to the other components in the system, which can include all four diesel generators if the other unit is unable to supply flow to its two diesel
~i generators.
However, TSI 90-03 imposes operability requirements on the BSEP SW systems which ensure a unit will' have 2 operable NSW pumps if it is required to supply all 4 diesel generators.
3.
Plant Operating Modes Service Water system functional and' operability requirements vary according to the specific plant operating mode. Also, as discussed earlier, certain design basis events are credible only in specific plant operating modes. -In the-following discussions. Modes 1, 2, and 3 are. considered to be bounded by one set of events and assumptions while Modes 4 and 5 are governed by another set.
The following discussion identifies the different assumptions which apply.
to each mode.
a.
Modes 1, 2, and 3 In Modes 1, 2, and 3, the most limiting maximum flow event is considered to be a LOCA outside primary containment for several reasons. The LOCA signal results in the greatest i
number of safety-related components being aligned to the SW
~
system. The diesel generators get an automatic. start signal and their jacket water cooler isolation valves open. The-
}
vital header valves are assumed open when analyzing for-I maximum SW pump flow demand since the Emergency Air compressors are non-Q and are assumed to fail, which results l
in failure of the air supply to the SW outlet isolation valves associated with these components. The Reactor Building becomes inaccessible due to the LOCA/HELB which means operator action cannot be taken to mitigate adverse impact on the SW system _in the after 10 minute phase of the l
event.
For.the minimum pump flow scenario, a LOOP event (without a LOCA) proves to be most limiting'since the i
standby NSW pump gets an auto start signal and no additional flow paths get aligned.
-t
!!! - 16 (4611NED.WP/che)
i b.
Modes 4 and 5 Two inportant factors differentiate Modes 4 and 5 from Modes l
1, 2, and 3.
First, an actual LOCA is not a credible event.
in Modes 4 and 5 since the reactor coolant piping is not j
significantly pressurized (Ref. UFSAR Sections 15.0.3.2.C and 15.0A.3.2.3.b).
However, a LOCA signal caused by l
operator error or instrumentation failure must be postulated since LOCA initiation instrumentation is still operable (Ref. Tech Spec.s 3/4.3 and 3/4.5).
Second, RHR SW pump operation is considered a credible initial condition-for the t
~
SW system before occurrence of the design basis event since RHR SW is normally in service during these operating modes.
i 9
4.
Specific Limiting Events The following section discusses specific system and component responses for the limiting events.
For each set of operating conditions, the NSW pumps are analyzed for.
maximum flow restrictions and minimum flow requirements.
Also, the SW system is analyzed for sufficient component cooling flow rates.
j l
a.
Modes 1, 2, and 3 t
For the 0-10 minute phase with maximum NSW pump flow, the single failure of an emergency power bus is assumed.
The loss of the E-bus disables one NSW pump and prevents one of tne RBCCW throttle valves (V103 or V106) from moving to its throttled position. This failure limits the number of available NSW pumps and maximizes flow to the nonsafety-l related RBCCW heat exchangers. Additionally, RBCCW flow is assumed to be at the maximum allowable flow rate before the event initiation.
Both maximum and minimum pump bay water l
1evel cases are analyzed since allowable NSW pump flows vary with NPSHA.
9 For the 0-10 minute minimum pump flow scenario, the assumed l
single failure is one of the RBCCW throttle valves goes to a f
fully closed rather than a throttled position.
The second NSW pump is assumed to start and no vital header loads are credited other than the one RHR room cooler required to be open by TSI 90-03.
The two diesel generator jacket water Ill + 17 (4611NFD.VP/che) i r,
m-.
i t
~
I
. cooler flow paths associated.with the particular unit are assumed to be open.
Though an event other than a.LOOPJ(or LOCA) would leave the DGs closed.this would not be as.
severe a case as the LOOP since the standby NSW pump would i
not start and an RBCCW throttle valve would'not fail shut (since it would get no signal to move in the first place).
i In the.after.10 minute case, the inaccessibility of the Reactor' Building coupled with'a LOOP and a single failure of
-l an E bus results in the worst-case challenge to the Service l
Water system capability to supply adequate cooling water.
The loss of the E-bus means power is unavailable to one of l
the RBCCW throttle valves. The other valve closes, but only El to its throttled position; manual action is: required to f
completely close the valve.
Since operator action cannot be taken to close the valve and isolate RBCCW due to the HELB, a significant amount of service water flow is lost to the-nonsafety-related RBCCW beat exchangers.
One mitigating f
factor in this scenario is a second SW pump can be~ manually started and aligned to the NSW header to provide additional cooling flow.
i b.
Modes 4 and 5
~
I i
A LOCA/HELB is not credible; however, a LOCA signal-is considered credible.
A LOCA signal concurrent with LOOP is postulated as the most limiting maximum flow event The LOCA and LOOP signals cause the diesel generators to' start and load to the E-busses.
For the 0-10 minute maximum pump flow case, the worst single failure is a function of the f
number of operable NSW pumps. The worst failure when a j
single SW pump is operating is the failure of_the trip coil
.l for one of the RHR SW pumps since operation of the RHR SW l
pumps is credible in-Modes-4 and 5.
The failure of the trip.
f coil allows the pump to restart when the DGs energize the E-buses, resulting.in a significant extra flow demand for.the j
SW system and SW pumps. The worst failure when two SW pumps
,I are initially operating is an E-Bus failure, Since it stops one of the SW pumps and also prevents RBCCW from fully
~
[
auto-throttling..the E-bus failure is the most limiting failure and has more adverse impact than an RHR SW pump trip coil failure.
For these scenarios, RBCCW flow and RHR SW i
111 - 1b (4611NED.WP/che) i
t i
flow are assumed to be at their maximum allowable flow rates 1
I (per EER 89-0253, Rev. 0) before the event.
.For the 0-10 minute minimum pump flow case, two scenartos f
are examined.
The.first assumes two NSW pumps are operating, RBCCW is at its minimum' allowable' flow rate I
initially (2500 gpm), and no vital header loads are aligned other than the one required RHR room cooler. The single failure is assumed to be the complete closure of one'RBCCW throttle valve.
The second scenario assumes one NSW pump operating, no RBCCW flow initially, and a single failure of one DC cooler supply valve.
SW pump bay water level is assumed to be at is lowest leve1 for both scenarios since
~
this results in the minimum. flow rate through the-SW pumps.
Throttling of RBCCW Valves V103 and V106 is credited in
-i accordance with Plant Modifications89-088 and 89-089, which implement LOOP closing logic circuits for these valves.
For the after 10 minute case, only one SW pump can be credited since the assumed single failure of an E bus makes the second operable SW pump unavailable for manual alignment to the SW system. Minimum pump bay water-level is. assumed since this results in the least amount of service water' flow ~
i available for cooling.
Required RHR SW flowfis assumed to be only 2500 gpm in Modes 4 and 5 due to reduced core decay heat (Ref. Calculation PCN-G0050A-11, Rev. 0).
The requirement for 18 psig RHR SW pump suction pressure is observed to ensure adequate NPSHA is still maintained.
l i
F.
Off-normal Onerations t
r The Service Water system design at BSEP Units 1 and 2 provides for protection against single failures by utilizing two separate service water subsystems: the-Nuclear SW header and the Conventional SW header.
These subsystems do not constitute completely independent, automatically available sources of service j
water to safety-related components.
Rather, the Service Water i
system is designed so either header - nuclear or conventional.-
can be aligned to any safety-related equipment requiring service
)
water.
In this way, a redundant source of service waterfis ensured even in the event of a single failure in the Service Water system.
The only exception to this; design philosophy is the.
diesel generators, which are provided backup service water by the III 19 (4611NED.WP/che)
~.
t l
3 f
Separability of the subsystems and the concept of redundancy are maintained by cross-connection isolation j
valves installed between the headers.
The capability of using the CSW header to back up the NSW header = l l
provides enhanced Service Water system design capabilities for normal and accident operating conditicus. However, utilizing these cross-connection capabilities during normal plant operation j
can also result in configurations which, when considered in concert with the single failure criterion, extend the Service Water system beyond its design capabilities.
These off-normal system lineups and their impacts on the SW system are discussed below.
1.
Vital Header Supply from the CSW Header The vital header is normally supplied from the nuclear header through Valve SW-V117.
Cross-connection isolation Valve SW V118 is normally open and conventional header supply Valve SW-Vill is closed. Valve SW-V117 is normally open, but also has an automatic opening logic on a LOCA signal to ensure a flow path is available to the vital header during the LOCA.
However, if the conventional header ~
l is being used to supply the vital header'during normal.
l operation. Valve SW-Vill will be open and a potential-problem is created.
If a LOCA signal is initiated, Valve l
SW-V117 will open to provide flow to the vital header.
But Valve SW-Vill will be open already and will stay open, I
providing an unwanted flow path from the NSW header to the-CSW header.
Since operator action cannot be assumed in the i
first 10 minutes of an event, the additional flow demand on j
the SW system and SW pumps could potentially result in SW pump damage due to runout and. insufficient NPSH.
This situation can be avoided by requiring either Valve SW-V116 to be closed or Valve SW-V117 to be closed with power removed whenever Valve SW-Vill is open. Then -if a'LOCA signal is initiated,Lthe closed' valve prevents loss of flow to the CSW header.
For required vital header cooling after
{
the first.10 minutes of the event, operator action can be r
credited to reestablish flow to the conventional header, or to close SW-V111 and open SW-V117 or SW-V116 to realign the vital header to the NSW header.
EER-89-0333,' Rev. O was f
!!! - 20 (4611NED.k'P/che) m
.u
b issued to establish appropriate restrictions when using the CSW header to supply the vital header.
2.
SW Lube Water Supply from the Intake Bay The supply for SW pump lube water is normally taken from whichever header (nuclear or conventional) is. operating at the higher pressure, with the lower pressure header being isolated by a check valve.
Isolation valves are provided in the individual lines from each header to permit isolation of.
.q one or both headers from the lube water supply system.
4 Isolation can be accomplished manually or through the action of the PS-136 logic, which isolates the SW headers from lube water on low SW header pressure. When both headers are isolated, the SW lube water pumps take suction f rom the intake bay through suction check valves.
A potential.
problem develops when both headers are isolated and the SW pumps are not in a high flow condition. The lube water' system is designed to ensure operation from the intake bay when SW header pressure is low -
i.e., when SW pump flow is high or when the' pumps are stopped. The lube vater pumps, when taking suction from the intake bay, may not be capable of supplying lube water at the required pressure (15 psi above SW pump discharge pressure) and/or quality when SW pump flows are lower and discharge pressure is consequently higher.
Intake bay water level also has a strong effect on lube water system performance in this scenario.
Short-term-operation under these conditions has been evaluated and determined to be acceptable (Ref. Calculation G0050A-17,
[
Rev-. O, " Loss of SW Lube Water Header Pressure").
Plant Modifications 82-220L and 82-221L address long-term operation of the lube water system.
3.
RHR SW Pump Surveillance Testing 1
-l As a safety related system supplying' safety-related components, the Service Water system is subject to. periodic testing, particularly Technical Specification-required testing.
Such testing can require the Service. Water system to be in an off-normal-configuration for a specified length of time. The impact of the off normal configuration on SW.
system response to an event must La
- aluated.
Testing of-some components such as the diesel generators does not
.]
21 (l.611NED.WP/che)
I
.l
g i
r adversely impact the SW system'since these components are normally aligned during the worst-case event and have been assumed open in the design analyses contained in this hydraulic report.
The most significant potential impact of periodic testing on the SW system occurs during operation of the RHR SW pumps in i
Modes 1, 2, and 3.
The worst-case scenario assumes the operating RHR SW pump (s) continues to operate during a design basis event (specifically, during the first 10 minutes of the event) as a result of~a single failure, pumping a significant amount of the total available service water system flow through the RHR heat exchanger and out of the SW system.
The additional flow demand on the Service Water system and SW pumps could potentially result in SW pump damage due to runout and RHR SW pump damage due to inadequate NPSHA.
Also, inadequate component cooling flows
{
in the Service Water system during the first 10 minutes of the event might result.
Operation of the RHR SW system during Modes 1, 2, and 3 is possible and is required at certain times.
However, this:
scenario is not considered to be a plant condition from which a design basis event must be assumed to occur..The basis for this position is developed from the Technical Specification requirements for equipment out-of-service.
Risks to plant safety associated with equipment out-of-service times have been' evaluated and accepted in the Technical Specifications provided the out-of-service restrictions associated with the particular equipment or safety systems are observed. Original Technical Specifications, as well as subsequent Technical Specification interpretations, permit one service water pump to be out-of-service up to seven days without other compensatory measures. During this time, the single failure is the pump out-of-service. Operation of both RHR SW pumps represents no more flow diversion than the equivalent of one service water pump.
Since RHR SW system operation in' Modes 1, 2, and 3 lasts only a few hours, the risk is well bounded by existing Technical Specifications. Also, operation for testing purposes reduces future risk by identifying failures-or system performance deterioration, thus offsetting the small risk associated with the testing. This position has 111 - 22 (4611NED.WP/che) s
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been reviewed by the Nuclear Licensing Department; concurrence is ' documented in a Licensing memorandum to E.- A.
5 Bishop 'from L. I. Loflin dated December 18., 1989.
To further ensure this assumption is.not invalidated, TSI i
~89-02, Rev. 0 limiting the out-of-service timeaof the RHR SW pumps to less than seven days has been implemented.
4.
Backup Core Flooding Another requirement of the BSEP Service Water systems isito provide emergency backup to the RHR systems. for core flooding as defined in Design Report No. 12.
The core flooding operation is accomplished by opening both isolation valves in the cross-tie line from the "B" loop RHR SW system to the RER system. However, Design Report No. 12 makes clear this operation is required only in the event of multiple equipment and/or system failures. Though such an.
event is outside the design bases of the SW systems, the cross-tie to the RHR system is provided as an additional defense in the extremely unlikely occurrence of a multiple failure event.
l 5.
SW Lube Water System Cross-connected Operation-The BSEP SW' Lube Water systems are also designed with a.
I degree of operational flexibility for two-unit operation.
If one unit's SWLW pumps arc isolated or inoperable for a i
period of time, the other unit's LV system can be cross-connected to the inoperable LW system via two normally closed isolation valves to provide the necessary lube water flow to the SW pumps. The additional LW flow supplied by the one unit in this scenario has not been included in the 4
hydraulic analyses. However, review of the analyses results indicates the SW pumps have sufficient flow margin to supply this extra lube water flow in all cases except extreme low _
i water level conditions.
Operation during extreme low water level conditions is possible, and the necessary restrictions i
on SWLW cross-tie operation have been identified as an i
action in this report (see Section I.C and Attachment 2).
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.i IV.
SINGLE FAILURE ANALYSIS
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The Single'Fai1ure Analysis for the BSEP. Units 1 and 2' Service Water Systems has been performed as a separate, design-verified' calculation.
The calculation number is C0050A-16 Rev. 1 and is included-in its l
entirety asSection IV of this hydraulic report.
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IV-1 (4611NED.WP/che)
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