ML18082A741
| ML18082A741 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 07/17/1980 |
| From: | Mittl R Public Service Enterprise Group |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| M-P80-69-15-1, N06-01-02-A, N6-1-2-A, NUDOCS 8007210219 | |
| Download: ML18082A741 (23) | |
Text
PS~G e Public Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 Phone 201/430-7000 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
20555 July 17, 1980 Attention:
Mr. A. Schwencer, Acting Chief Licensing Branch 3 Division of Licensing Gentlemen:
PROPOSED CONCEPTUAL DESIGN ECCS AUTOMATIC SWITCHOVER NO. 2 UNIT SALEM NUCLEAR GENERATING STATION DOCKET NO. 50-311 PSE&G hereby submits its proposed conceptual design for automatic switchover of the ECCS from the injection phase to the recirculation phase of operation.
This document is submitted pursuant to the requirement set forth in Technical Specification 9.2.
It is anticipated that the final design package for this modification, can be submitted for your review and approval by September 1, 1980.
The scope of the changes involved in this design modification is such that implementation of the modifications must be performed during a refueling outage.
It is therefore anticipated that the modifications described herein can be implemented during the first refueling outage, estimated to be late 1981, provided your approval of this design modification is granted prior to end of 1980.
The Energy People 95-0942
Director of Nuclear Reactor Regulation 7/17/80 Should you have any question in this regard, do not hesitate to contact us.
EAL~bm N06 01/02-A Very truly yours, R. L. Mittl General Manager-Licensing and Environment Engineering and Construction
M P80 69 15/1 CONCEPTUAL DESIGN ECCS SWITCHOVER MODIFICATIONS NO. 2 UNIT SALEM NUCLEAR GENERATING STATION A.
Salem Unit 2 ECCS Switchover Evaluation Summary A comprehensive review has been performed of the Salem Unit 2 ECCS switchover design and procedures with the objective of identifying modifications, if appropriate, to optimize the reliability of achieving a stable long-term recirculation mode of post-LOCA operation.
This review focused on those aspects of the ECCS design and procedures that must be accomplished in a timely fashion following receipt of the refueling water storage tank (RWST) low level alarm in order to ensure continued ECCS pump flow to the reactor coolant system while protecting the ECCS pumps from damage as their suction source is being transferred from the RWST to the containment sump.
This review was limited to that portion of switchover that is important in ensuring that all ECCS pumps are protected against loss of suction source.
This evaluation addressed the many interdependencies that affect the switchover aspect of the ECCS design.
Included in this optimization evaluation were the fol-lowing requirements and guidelines.
a}
NRC requirements that accompanied the request.
b}
Guidelines fo.r RWST sizing as related to optimizing the effectiveness of the RWST transfer allowance.
c)
Guidelines for operator action.
d}
Guidelines for accident identification and mitigation.
Based on the above, the several switchover steps that are important to protecting the ECCS pumps from loss of suction source were evaluated to identify the advantages and disadvantages of automation.
This evaluation, indi-cated that four steps can be automated in order to init-iate switchover and to reduce the number of operator ac-tions required to complete switchover.
Such automation can be initiated with energize to actuate logic consist-ing of two out of four RWST low level signals concurrent with safety injection signal.
To support this level of automation and to optimize the automation benefits, it is necessary to add check valves in each of the RHR pump suction lines from the RWST and M P80 69 15/3 the containment sump.
This level of automation permits the systems to perform their function despite any single postulated instrument or control system single failure.
No single failure will a) prevent automatic initiation of switchover or b) prematurely initiate switchover ac-tions that affect both trains in an unacceptable man-ner.
Automating beyond this extent makes the switchover design susceptible to unacceptable single failures that may reduce ECCS flow to the reactor coolant system below minimum requirements.
Reviewing the steps that cannot be automated, it was de-termined that they are few in number and can be struc-tured in a procedure that can be implemented based only on operator verification that switchover to recircula-tion is required (i.e. RWST level is low and sump level is adequate to support residual heat removal pump NPSH requirements).
This switchover procedure can be struc-tured to minimize and emphasize the operator actions that must be performed to protect all ECCS pumps from loss of suction source.
The procedure can further be performed independent of prior ECCS single failure or can tolerate an operator error single failure which re-sults in a) the failure to perform one step, or b) the performance of one step out of sequence.
This switchover automation evaluation indicated that a semiautomatic switchover consisting of automatic initia-tion and manual completion combined the advantages of automation with the advantages of an unambiguous proce-dure wherein operator actions are minimized.
The design modifications required to implement this semiautomatic switchover design are described in Paragraph B.
To ver-ify that this combination of automatic and manual ac-tions constituted an optimized design, the proposed de-sign was evaluated relative to existing guidelines for RWST sizing, operator action, and accident indentifica-tion and mitigation procedures.
A summary of this eval-uation follows.
The Salem Unit 2 RWST design incorporates level set-points (1) which provide approximately 214,000 gallons for injection phase operation.
Asuming all ECCS pumps operate at maximum runout(2) during the injection phase, total maximum RWST outflow is approximately 15,000 gpm.
Assuming that all ECCS pumps operate at maximum runout from the initiation of the LOCA, the earliest time after M PSO 69 15/4 LOCA initiation that switchover will be automatically initiated is approximately 14.3 minutes.
This early switchover initiation requires rapid depressurization of the reactor coolant system to low pressures (i.e. ap-proximately 0 psig) in order to permit the ECCS pumps to operate at runout conditions from LOCA initiation.
Such a rapid depressurization would be characteri~tic of the hypothetical double ended large LOCA.
For smaller post-ulated LOCAs, the depressurization transient is not as rapid and ECCS pump flow during the depressurization transient is less than 15,000 gpm.
The effect of this reduced ECCS flow during the depressurization transient results in a longer injection phase.
This effect is demonstrated for small LOCAs < 6 inch in diameter which exhibit depressurization transients that stabilize above approximately 200 psig, assuming all ECCS pumps operat-ing.
Throughout such depressurization transients, the RHR pumps will not deliver flow to the reactor coolant system.
Assuming that the remaining ECCS pumps (i.e.
charging and safety injection pumps) and the containment spray pumps operate at maximum runout during the injec-tion phase, total RWST outflow is approximately 7000 gpm.
Based on this RWST outflow, switchover will be automatically initiated at approximately 30.5 minutes after LOCA initiation.
This time is conservatively short since the charging and safety injection pumps will not operate at runout for this category of LOCA and the containment spray pumps will not automatically start simultaneous with LOCA initiation.
The Salem Unit 2 RWST design incorporates level set-points which provide approximately 129,300 gallons for the transfer allowance.
The effectiveness of this al-lowance in providing time for the operator to perform any necessary switchover manual actions is also depend-ent on the size of the LOCA and the RWST outflow during switchover.
The minimum time available for switchover operations can be conservatively enveloped by comparing the maximum RWST injection phase outflow of 15,000 gpm with the RWST transfer allowance of 129,300 gallons.
This comparison indicates that a minimum time of approx-imately 8.5 minutes is available for the operator to perform the necessary switchover manual actions to en-sure a continued suction source to the charging and safety injection pumps.
This time includes conservatism since the switchover automatic actions of opening the containment sump isolation valve and closing the RWST M P80 69 15/5 isolation valves function to automatically reduce RWST outflow to approximately 7000 gpm during the entire switchover period since the RHR pumps will not be deliv-ering flow to the reactor coolant system.
The plant emergency instructions are structured to identify the type of accident and to direct the operator to the appropriate procedure to mitigate the identified accident.
For any accident that is characterized by in-creasing containment radiation, containment pressure or containment sump level, the operator is directed to the LOCA procedure.
The LOCA procedure includes cautions to the operator to prepare for switchover from injection to recirculation.
For any LOCA that is characterized by a rapid depressurization to low reactor coolant system pressures, the cautions include go-to steps to skip di-agnostic and verification steps and prepare the operator for a timely switchover to recirculation.
In this way the emergency instructions are structured to prepare the operator to anticipate the RWST low level alarm and to perform any switchover manual actions in a timely fash-ion.
For the smaller more credible LOCAs (i.e. < 6 inches in diameter), that are characterized by more gradual depressurization transients, the operator will have more time to perform the necessary diagnostic and verification steps required to identify this category of LOCA.
The proposed semiautomatic switchover was evaluated rel-ative to the NRC requirements and determined to comply with these requirements.
B.
Switchover Modifications The Salem 2 design for manual switchover of the ECCS from the injection phase to the recirculation phase will be modified to minimize required operator actions by automatically initiating selected steps of the proce-dure.
The design of this automatic system involves the specific changes identified below which meet the NRC de-sign criteria shown in Attachment 1, except as noted.
- 1.
RHR Pump Suction Piping from Containment Sump Each line from the containment sump to the suction of its respective RHR pump will be modified by in-stalling a check valve between the pump suction M P80 69 15/6 connection and the containment sump isolation valve (SJ44).
These check valves will be designed to Seismic Category 1 criteria and will be provided with a mechanism to determine the valve position by inspection at the valve location.
The purpose of these valves is to preclude draining the RWST into the sump if the sump isolation valves were to be opened inadvertently.
- 2.
RHR Pump Suction Piping from RWST Each RHR pump suction line from the RWST will be provided with a check valve downstream of the pump suction valve (RH4) and before the connection point of the sump suction piping.
These valves will be designed to Seismic Category 1 criteria and will be provided with a mechanism to determine valve posi-tion by inspection at the valve location.
The purpose of these valves is to preclude both RHR Pumps attempting to take suction from one sump line in the event of a failure of one sump isolation valve to open.
- 3.
Automatic Switchover Logic Four RWST level transmitters will be used to pro-vide input signals to the Solid-State Protection System (SSPS).
These signals, and the 2 out of 4 Low-Level logic, will be designed to the same criteria as the existing protection system function of safety injection initiation with the following exceptions:
- a.
The level bistables will be normally de-energized*.
A low-level condition will result in energization of the bistables to provide inputs to the SSPS.
This is essentially identical to the design provided for initiation of containmnt spray.
- b.
The switchover sequence signal may be reset in the Control Room at any time on a single train basis.
M P80 69 15/7
- c.
Manual initiation at the system level is not provided.
The remaining features of the system will meet the re-quirements of IEEE 279-1971.
- 4.
Sump Isolation Valves Prior licensing considerations required that the sump isolation valves (SJ44) be provided with:
- a.
Lockout of power to prevent spurious opening.
- b.
An interlock to prevent opening unless the RWST to RHR pump suction valve (RH4) is closed.
To facilitate automatic opening of the sump valve, the power lockout is to be removed and the opening interlock from RH4 will be bypassed upon receipt of a switchover sequence signal.
For normal operating conditions, the interlock will remain functional to provide for test-ability of the automatic switchover sequence signal.
In addition to the design changes described above, simp-lified emergency operating procedures will be developed to further enhance the operator's ability to effectively deal with design basis accidents. is an updated version of the information presented at the meeting with the NRC staff on June 5, 1980.
M P80 69 15/8
ATTACHMENT 1 DESIGN CRITERIA ECCS SWITCHOVER MODIFICATIONS
- 1.
The minimum flow entering the reactor coolant system during and after the switchover shall be sufficient to remove fission product decay heat assuming any single active failure.
- 2.
The design of the controls and instrumentation shall permit manual operation of the ECC and containment spray systems from the control room at the component level both prior to and after the transfer to the recircula-tion mode has been accomplished.
- 3.
The switchover of the ECCS from the injection to the re-cirulation mode of operation shall be automated to the maximum feasible extent, such that required operator ac-tions are minimized, and uninterrupted ECCS flow is pro-vided to the core.
- 4.
The systems must be able to perform their function de-spite any single postulated single failure of a fluid system.
No single failure shall:
- a.
Prevent automatic transfer to the recirculation mode of operation or
- b.
Cause inadvertent automatic transfer to the re-circulation mode of operation of both trains of the ECC or the containment spray systems.
- 5.
The design of the controls and instrumentation shall meet IEEE Std. 279-1971.
- 6.
The ESF switchover system shall use seismically quali-fied components and the switchover shall be to a seis-mically qualified water supply.
- 7.
To reduce the probability of the operator prematurely performing manual actions in the switchover procedure, the procedures shall include provisions for the verif ic-ation of the water storage tank level prior to beginning the manual switchover actions.
M P80 69 15/9
ATTACHMENT 2 Switchover Automation Evaluation Switchover Modifications Switchover Sequence Logic Switchover Procedure Switchover Features Switchover Failure Mode Effects Analysis M P80 69 15/10
Action SWITCHOVER AUTOMATION EVALUATION
( 1)
Advantages Disadvantages Auto Open 21 SJ44, 22SJ44 o
Provides sump suctlon/NPSH for RHR pumps without operator action.
o Fa i I u re of one sump va Ive to open on demand cou Id damage both RHR pumps. C 2)
Auto Close 21RH4, 22RH4 Auto Open 21CC16, 22CC16 Auto Open 21SJ113, 22SJ113 Auto Close 21RH19, 22RH19 Auto Close 2SJ67, 2SJ68 Auto Open 21SJ45, 22SJ45 NOTES:
o Minimizes RWST outflow fol lowing sump valve opening without operator action.
o Provides component cooling water to RHR Hx without operator action.
No operator decision/verif icatlon required.
o Opens SI/CHG pump suction crossover header without operator action.
No operator decision/verification required.
o Closes RHR discharge crossconnect valves without operator action.
o Isolates SI minlflow without operator action.
o Provides suction/NPSH for SI and CHG pumps from RHR pump discharge without operator action.
Cl>
Al I automatic steps have advantage of reducing operator actions.
o Spurious (early) opening could damage one RHR pump.
o Opening could permit 3
~otentlal backflow from RWST to sump.
o Spurious (early> sequential automatic closure before adequate water exists In sump could damage one RHR pump.
o None o
None o
Spurious (early) sequential automatic closure reduf~J ECCS below minimum safeguards.
o Spurious (early> sequential automatif 5>
closure cou Id damage both SI pumps.
o Closure of valves RH19 and SJ67, 68 are required to be completed prior to opening valves SJ45.
( 2)
Unacceptable Single Failure -
Failure to open on demand could permit two RHR pumps to draw suction from one sump IA*,.
Resolution requires addition of a 14 inch check valve In each RWST I ine.
~
(3)
Affects RWST Sizing <Transfer Allowance) -
Requires Ca) modification to RWST sizing basis, (b) addition of 14 inch check valve In each sump line, or Cc) auto closure of RWST suction MOV.
Modifications bl and c) will prevent and minimize, respectively, potential backflow to the sump when the sump MOV opens.
(4)
Unacceptable Single Failure -
Spurious sequential closure results in damage to one RHR pump and reduces ECCS flow below minimum safeguards.
Resolution requires additional logic/permissive to prevent spurious sequential automatic closure.
(5)
Unacceptable Single Failure -
Spurious sequential closure results in damage to two SI pumps, reducing ECCS flow below minimum safeguards.
Resolution requires modification to locate two MOVs in each SI pump mlniflow line Cone on train A and one on train B to ensure isolation for recirculation).
Also requires additional logic/permissive to prevent spurious sequential closing of a valve (e.g., train A valves) in each SI pump mlniflow.
M P 80 69 I 5 I 1 I I 2
SWITCHOVER MODIFICATIONS Design Modifications o
Add sump check valves (verify adequate NPSH).
o Add RWST check valves (verify adequate NPSH).
o Automate switchover actions (See Switchover Logic).
o Open SJ44 (on RWST "S" signal) 0 Close RH4 (on valves 0
Open CC16 (on RWST signal).
0 Open SJ113 (on RWST signal).
o Maintain manual actions o
Close SJ67, 68 o
Close RH19 o
Open SJ45
- low level and concurrent SJ44 full open signal).
low level and concurrent
- low level and concurrent o
Implement simplified' switchover procedure o
See Switchover Procedure M P80 69 15/13 "S II "S"
S w t TC t\\o '* E. R s E <P '-' ~ N C G L D l~f I C....
--~--------
s
~
( Si"'EP I CLo$E
.s:rc,7 S.768' r,n 1.:.. I
- I-r -~
lsJ/13.
1L (i?) y l<w.51 LEV'=.L Av Top'\\ AT ;C.
Ac110.Js MAf'Jl>At..
Ac..1 \\o NS Tf?A\\N "'B'
- o.
---*---*-----t:{i
SWITCHOVER PROCEDURE No operator action is required prior to 10 minutes after the accident.
Prior to the receipt of the RWST low level alarm, the operator is to:
CAUTIONS Verify that all safeguard pumps are operating and are delivering flow to the RCS cold legs.
(If the SI and RHR pumps are not delivering flow to the RCS, due to the fact that the RCS pressure is higher than pump discharge pressure, shut off the applicable pumps.)
Monitor RWST and containment sump level in anticipation of switchover initiation.
The manual switchover steps listed below are to be performed in an orderly and timely manner and in the proper sequence.
These operator actions are not to be interrupted until all of the steps in the table are completed.
If the RWST low-low level alarm is received at any time prior to completion of Step 3, immediately stop any pumps still taking suction from the RWST, then complete the switchover and restart any pump which was stopped.
SWITCHOVER STEPS Upon receipt of the RWST low level signal, the operator is to immediately verify RWST low level and containment sump minimum level and to perform the following actions.
Step l Step 2 Step 3 Restore power to and close the safety injection pump miniflow valves (SJ67, 68).
Close the two valves in the crossover line downstream of the RHR heat exchangers (RH19).
Open each valve from each RHR pump discharge line to the safety injection pump suction and to the charging pump suction (SJ45).
M P80 69 15/14
Step 4 Step 5 Step 6 Step 7 SWITCHOVER PROCEDURE (Cont'd)
All ECCS pumps are now aligned with suction flow from the containment sump.
Verify proper position of automatically operated valves.
a) b)
SJ44 SJ113 CC16 RH4 Open Open Open
-Close Complete the following manual actions to provide redundant isolation of the RWST from the recirculation fluid.
Restore power to and close the valve in the common line from the RWST to both RHR pumps (SJ69).
Close the two parallel valves in the line from the RWST to the charging pump suction (SJl, SJ2).
Restore power to and close the valve in the common line from the RWST to both safety injection pumps (SJ 3 0)
- M PBO 69 15/15
SWITCHOVER FEATURES o
Flow is uninterrupted from all ECCS pumps during switchover.
o The automatic actions can tolerate any postulated instrumentation and control or mechanical single failure without (a) preventing automatic transfer to recirculation, or (b) causing inadvertent (spurious) automatic transfer to recirculation.
o The complexity of the automatic actuation logic and interlocks is minimized.
o The manual actions can tolerate any postulated single failure without preventing transfer to recirculation.
This includes an operator error single failure which results in (a) the failure to perform one step, or (b) the performance of one step out of sequence.
o The operator manual actions are minimized.
o The manual switchover steps can be performed independent of single failure.
Upon verification that switchover is required (i.e., RWST low-low level and minimum sump level), the switchover can be completed without any additional operator decision/verification.
M P80 69 15/16
Component
- 1. Motor-operated gate valve 21SJ44 C22SJ44 analogous)
M P80 71 07/1 Fa i I ure Mode al Falls to open on demand.
bl Opens on spuri-ous demand.
ECCS SWITCHOVER FAILURE MODE EFFECTS ANALYSIS ECCS Function Recirculation - sump Isolation.
Effect on System Operation al Fa i I ure reduces redundancy of pro-vi ding fluid from the containment sump to the RCS during recircula-tion.
RHR pump 21 (pump 22) will not provide recircula-tion flow.
Minimum LHSI flow require-ments will be met through opening of Isolation valve 22SJ44 and recircu-lation of fluid by RHR pump 22 (pump 21).
bl Failure prematurely a 11 gns RHR pump 21 Cpump 22) to the containment sump.
Ml nlmum LHSI reci r-cu latlon flClll re-quirements wll I be met through proper opening of Isola-tion valve 22SJ44 and recirculation of fluid by RHR pump 22 (pump 21 J.
Fa! lure Detect I on Method*
Valve position Indi-cation at MCB.
Valve open position monitor light and alarm for group monitoring of com-ponents at MCB.
Remarks Valve ls automatl-cal ly actuated to open by an S signal in coincidence with two out of four 11 I ow-I ow level" RWST s I gnal.
Component
- 2. Motor-operated gate valve 21RH4 M PBO 71 07/2 Failure Mode a) Fa! Is to close demand.
bl Closes sequen-t i a I I y on spur i -
ous demand.
ECCS SWITCHOVER FAILURE MODE EFFECTS ANALYSIS ECCS Function Recirculation - RWST isolation.
Effect on System Operation a) F al I ure reduces redundancy of pro-vi ding flow isola-lation of contain-ment sump from RWST.
No effect on safety for system operation.
RWST check Isolation va Ive prov I des back-up Isolation.
b) Failure prematurely Isolates RHR pump 21 C pump 22) from the RWST.
Minimum LHSI recirculation flow requirements w i 11 be met through proper c I os i ng of Isolation valve 22RH4 and reclrcu-1 at ion of f I u Id by RHR pump 22 (pump 21 >.
Failure Detect I on Method*
Valve position Indi-cation at MCB.
Valve close position mon I tor 11 ght and alarm for group monitoring of com-ponents at r-<<:s.
Remarks Valve is automatl-ca I I y actuated to close by a ful I open signal from sump I so-l at Ion valve 21SJ44.
Component
- 3. Motor-operated gate valve 21SJ113 M PBO 71 07/3 Failure Mode al Fai Is to open on demand.
bl Opens on spuri-ous demand.
ECCS SWITCHOVER FAILURE MODE EFFECTS ANALYSIS ECCS Function Recirculation - CHG and SI pumps suction cross connect Isola-tion.
Effect on System Operation al Fa 11 ure reduces redundancy of pro-vi ding fluid flow through cross-tie between suction of CHG pumps and S pumps.
No effect on safety for system operation.
Alternate isolation valve 22SJ113 opens to provide back-up flow path through cross-tie 11 ne.
bl Failure prematurely opens the crosscon-nect between the CHG pump and SI pump suction.
No effect on safety for system operation.
NPSh from RWST to CHG and SI pumps Is not affected.
Failure Detection Method*
Same method of detection as those stated for item 1.
Remarks Valve ls automati-cally actuated to open by an S signal In coincidence with two out of four "I ow-I ow level" RWST signal.
Component
- 4. Motor-operated gate valve 21CC16 M PBO 71 07/4 Failure Mode a) Fails to open on demand.
bl Fai Is open on spurious demand.
ECCS SWITCHOVER FAILURE MODE EFFECTS ANALYSIS
-~
ECCS Function Recirculation - RHR Hx cooling isola-tion.
Effect on System Operation al Failure reduces redundancy of pro-vi d Ing fluid flow for cooling of RHR Hx 21 CHx 22) dur-1 ng recirculation.
No effect on safety for system opera-tion. Alternate Isolation valve 22CC1 6 opens to provide cooling to redundant RHR Hx 21 CHx 22).
b) Fal I ure premature! y prov I des coo I Ing flow to RHR Hx 21 CHx 22).
No effect on safety for system.
Fa I I ure Detect I on Method*
Same method of detection as those stated for Item 1.
Remarks Valve Is automatl-ca I I y actuated to open by an S signal in coincidence with two out of four "I ow-I ow level" RWST signal.
e e
Component
- 5. Motor-operated gate valve 21RH19
- 6.
Motor-operated glove valve SJ 67.
M PBO 71 07/5 Fa 11 ure Mode Falls to close on on demand.
Fa! ls to close on demand.
ECCS SWITCHOVER FAILURE MODE EFFECTS ANALYSIS ECCS Function Recirculation - RHR pumps d I scharge crossconnect Isola-tion.
Recirculation - Sl pump miniflow Isola-tion.
Effect on System Operation Failure reduces re-dundancy of provid-ing RHR pump train separation for reclr-cu lation of fluid to cold legs of RCS.
No effect on safety for system operation.
Alternate lsilation valve 22RH19 provides back-up isolation for R~ pump tra In separation.
Fa I I ure reduces re-dundancy of providing Isolation of Sl pump mlnlf low to the RWST.
No effect on safety for system operation.
Alternate isolation valve SJ68 In mlnlflow line provides back-up Isolation.
Failure Detect I on Method*
SC111e method of de-tection as those stated for Item 2.
Same method of de-tect ion as those stated for Item 2.
Remarks Valve ls not automatl-cal ly actuated to close.
1 l Valve Is not auto-mat i ca I I y actuated to close.
- 2) Valve is electri-ca I I y inter locked with I so lat Ion valve 21SS45 and may not be remote-1 y opened unless these va Ives are closed.
Component
- 7.
Motor-operated glove valve 21 SJ45
- 8.
Motor-operated gate valve 22SJ45 Failure Mode Fat Is to open on demand.
Fai Is to open on demand.
ECCS SWITCHOVER FAILURE MODE EFFECTS ANALYSIS ECCS Function Recirculation -
Crossover from RhR 21 discharge to Sl pump suction.
Recirculation -
Crossover from RHR pump 22 discharge to CHG pump suction.
Effect on System Operation Failure reduces re-dundancy of providing t\\PSH to suction of Sl pumps from RHR pumps.
No effect of safety for system operation.
Minimum NPSH to SI pump suction will be met by flow from RHR pump 22 via cross tie Ii ne and opening of isolation valve 21SJ113 or 22SJ113 and isolation valve 22SJ45.
Failure reduces re-dundancy of providing NPSH to suction of CHG pumps.
No effect of safety for system operation. Minimum NPSH to CH pump sue-t I on wil I be met by flow from RHR pump via cross-tie line and opening of isolation valve 211SJ113 or 22SJ113 and Isolation va Ive 21 SJ45.
Fa i I ure Detect I on Method*
Same methods of de-tect Ion as those stated for Item 1.
S arre methods of de-tect I on as those stated for Item 1.
- As part of plant operation, periodic tests, surveillance inspections, and instrument calibrations are made to monitor equipment and performance.
Failures may be detected during such monitoring of equipment in addition to detection methods noted.
M PBO 71 07/6 Remarks 1 l Valve Is not auto-matically actuated to open.
- 2) Valve ls electri-cally Interlocked and cannot be remote I y opened unless valve SJ68 ls closed and valve RHl or RH2 is closed.
1 l Valve ls not auto-mat i ca I I y actuated to open.
- 2) Valve ls electrl-caly interlocked and cannot be remote I y opened unless valve SJ68 is closed and valve RHl or RH2 is closed.