ML20059E540
| ML20059E540 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 08/21/1990 |
| From: | Chu E, Fleischman B GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20059E534 | List: |
| References | |
| EDE-06-0290, EDE-06-0290-R02, EDE-6-290, EDE-6-290-R2, NUDOCS 9009100227 | |
| Download: ML20059E540 (5) | |
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EDE-06-0290, R2 (DRF#C51-00082) 1 Jl GENERAL ELECTRIC COMPANY
. REMOVAL OF i
APRM DOWNSCALE' SCRAM-SETPOINT FOR PUBLIC SERVICE ELECTRIC & GAS HOPE CREER i
Prepared by.
72u/Td E. M. Chu, Senior _ Engineer 1
Reactor Protection Systems and Application Engineering i
i sad Approved by:
WOOF //. ?, /-4.
' 8-U N 8( F..FI4fschmEn,; Manager Reactor Protection Systems and Application Engineering l
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l' BACKGROUND The Average Power. Range Monitor (APRM) downscale scraa trip exists on several Boiling Water Reactor-(BWR/3 and-BWR/4)-
plants. including Hope Creek.
This APRM trip was dtsfc'ed to reactivate the Intermediate Range Monitor (IRM);ups d a scram function when~the associated APRM channel is downscale in the RUN mode.. The design was'later deleted by General l
Electric Nuclear Energy (GENE) on BWR/5 and BWR/6 plants.
because it was judged to be performing:no function with a-value commensurate with the surveillance required.
Based on the same rationale, GENE has supported-severt1 BWR BWR/4 plants to remove the APRM downscale trip.requ/3 and irement from their Technical tjecifications.
In response to a request from Public Service Electric and Gas (PSE&G)', GENE has developed the following baris-to support a Ecpe Creek licensing amendment to eliminate the'APRM downscale trip requirement.
DESIGN BASIS The original philos'ophy behind including the APRM downscale scram was to provide protection against loss of monitoring
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capability when changing'from the STARTUP to the RUN mode.
If the operator switched to the RUN mode before the'APRMs l
were on scale, the IRMs would continus.to. provide: input for a high neutron flux scram.
neutron flux monitoring still exists.The need for such continuity.in PSE&G has verified that the changiag of modes ofioperation is well controlled at. Hope Creek.by the' operational.
procedures: OP-IO.22-003 l
Rated Power)- and CP-IO.22-004(Startup.From Cold Shutdown to (Shutdown From Rated Power to Cold Shutdown).
neutron flux monitoring at Hope Creek is= insured viaOutside of n abnormal-operating precedures.and alarm response procedures:
OP-AB.22-108 (LPRN/APRM Malfunction) and OP-AR.22-009.:(APRM Downscale).
Since surveillance testing of the downscale trip places a significant hardship on-the utilities, the IRN automated.
trip requirement in the RUN mode:was reevaluated:and-eliminated in_later BWR product lines based on the justification outlined in the DISCUSSIONS and CONCLUSION sections. Elimination of the Hope. Creek APRN downscale trip confarms with these later product lines E design basis.
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DISCUSSIONS i
l The Neutron Monitoring System design requires'a minimun
related systen functions. number.of functional APRM channels to perform the sa Whenever an APRM channel'is downscale in the-RUN! mode, the channel.is considered non-functional..
Since the APRM can no longer perform the.
intended satety functions properly, the Intermediate Range Monitors (IRMs) are activated to perform the safety functions.
i However, as long as the' total number of functional-APRM channels is above the minimua> channel requirement, channels being downscale will not prevent the
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-APRM system from performing its safety-functions.
' If, because of either. prematurely: entering the RUN mode during-startup or-having APRMs downscale before entering the.
STARTUP moda during power: descent, met, the plant abnormal. operating this requirement is not corrective ~ action within one hour. procedures shall require a
-This time. period will reduce the probability"of an accident or transient requiring a scrum from-APRM when'in these conditions.
strict controls on the chanThe plant operating procedures also place j
condition to another-(e.g.,ging from one operational-
-STARTUP to RUN).-
Prior to entering the~RUN mode, the APRMs shall satisfy:their-respective requirements (e.g., minimum number of channels above downscale'setpoint).
If these, minimum requirements are not satisfied, the operator is not allowed to switch-from the STARTUP mode'to the RUN mode.
CONCLUSION 3
As discussed above, the operator errors of prematurely going to the RUN mode during startup or delaying shifting from the RUN mode during shutdown (resulting in too many downscale APRM channels).do not result:in a significantly degraded APRM safety function.
The APRM downscale rod block trip will continue to both prohibit control rod withdrawal ~ errors and power ascension during the time-period' required to take the corrective action required by the plant procedures.
is for these reasons, together with the extensive It surveillance required for the function, that the APRM downscale trip is recommended to be deleted-from the Hope Creek plant.
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9 ATTACHMENT-4 SIGNIFICANT HAZARDS CONSIDERATION proposed-change to the Technical Spec (ifications in hazards consideration.
Station in accordance with proposed Technical Specification L
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Involve a significant increase in the probability or consequences of an accident-previously evaluated because:
The accidents of concarn with respect to the APRM/IRM companion scr I
caused by either an; APRM downscale or an IRM "high high" or inoperable trip, are the Rod Orop Accident (RDA) and the low' power.-Rod Withdrawal L
Error (RWE).
function in the termination of either of these accidents.FSA
. scram function is not credited in the termination'of these accidents, the Since this elimination of this scram function has no adverse ~effect on previous evaluated accidents.
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previously evaluated because: Create the possibility cf a new or d Startup and Run Modes are well understood an reload safety analyses.
Elimination of the APRM downscale or inoperable caused scram does not-introduce any new a/IRM "high high" since it is not credited-in the termination of these events ccident scenerio L
RHE).
Less limiting events in this region such as control rod initiated fast period events either due to operator error or'CR0 malfunction are subsets of the low power RWE event and are bounded by both it and th t
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Design Basis RDA.-
reactivity insertion events occurring with an'inaIn. addition,. Ge position, the 'only effect of the-deletion. of-the,ppropriate mode switch APRM downscale scram would be that the initial power lovsl could be a few ' percent lower General' Electric has indicated that this would not have a significant j
effect on:the severity of the event.
3 Involve a>significant reduction in the' margin of safety because:
The APRM downscale/IRM "high high" 'or inoperable caused scram is credited in the-termination.of any transient.which could challange a safety limit.
As'such, the elimination of.this scram -funct. ion has no effect on any Technical Specification defined safety margin.
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SIGNIFICANT HAZARDS CONSIDERATION aPoo0VALS GENERAL ELECTRIC:
P:epared by -
4 ' 711 >
Oate 3 - f-90 M. E. Urata, Principal Licensing Engineer Plant Licensing Services Concurred.by -
/A Date.:3-7~7d E. M. Chu. Senior Engineer a
Reactor Protection Systems and Application Engineering Approved by
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A D. J. Robare. Manager Date 3 - 9 ~~ $ O U
P1 ant Licensing Services l
EDE-06 0290 DRF#C51 00082 i
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