ML17252A757
| ML17252A757 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, LaSalle  |
| Issue date: | 06/03/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17252A756 | List: |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 GL-82-33, NUDOCS 9306100328 | |
| Download: ML17252A757 (5) | |
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c" UNITED IT Ans NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. IClll6 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO REGULATORY GUIPE 1.97 POST-ACCIDENT NEUTRON FLUX MONITORING INSTRVMENTATJQN FOR BQILING WATER REACTORS
1.0 INTRODUCTION
Section 6.2 of Generic Letter 82-33 (Reference 1) requests applicants and licensees to provide a report on their implementation of Regulatory Guide (R.G.) l.97, Revision 2 (Reference 2), and 111ethods for complying w1th the Convnission's regulations, including supporting technical justification of any proposed deviations or alternatives. A review of the applicants* and licensees' submittals was performed and a safety evaluation (SE) was issued for each plant. These SEs conclude that the applicants and licensees either conformed to, or adequately justified deviations from, the guidance of R.G.
1.97 for each post-accident monitoring variable except for the variables identified in the SEs.
A large number of Boiling Water Reactor (BWR) applicants and licensees requested deviations from the regulatory guide position for Category 1 neutron fiux monitoring instrumentation.
The R.G. l.97 Category 1 criteria includes environmental qualification, seismic qualification, Class lE power sources, and red~ndant channels.
Current operating BWRs, with the exception of Susquehanna Steam Electric Station Units l and Z and Washington Public Power Supply Nuclear Project {WNP-2), do not have environment1lly qualified neutron flux monitoring instrumentation.
However, none of the submittals requesting neutron flux monitoring instrumentation deviations provide sufficient justification for granting the deviations. These requests were denied to the applicants and licensees, except for Limerick Generating Station Units 1 a~: 2.
~:::t1ona11y, Sig Rock Point is not bound by the provisions of R.G. l.97.
1r.
s~~~:~t of these requests the BWR Owners Group submitted NE00-31558
~P~sition on NRC Regulatory Guide 1.97, Revision 3, Requirements for Post-Accident ~eutron Monitoring System" (Reference 3).
The NEDO report proposes criteria for neutron flux monitoring instrumentation, in lieu of the Category l criteria included fo R.G. 1.97, Revision 3 (Referen_ce 4).
The staff rejected the BWR Owners Group proposal (Reference 5) because of the judgement lt1at neutron flux is fundamentally a key safety parameter and existing neutron flux monitoring instrumentation is not likely to survive a post-accident harsh environment.
The BWR Owners Group appealed the staff's position to the Director of the Office of Nuclear Reactor Regulation (NRR)
(Reference 6).
The Director of NRR upheld the appeal (Reference 7) and concluded that Category l neutron flux monitoring instrumentation is not needed for existing B~Rs to cope with Loss-of-Coolant Accident (LOCA), Anticipated Transient Without Scram (ATWS), or other accidents that do not result in severe core damage conditions. Instrumentation to monitor the progression of core melt accidents would be best addressed by the current severe accident management program.
,.. Therefore, for existing BWRs, the stiff will accept the criteri1 of NED0-31558.
However, for new license applic1tions for both convention1l and advanced BWR designs there will be no ch1nge in the R.G. J.97 criteri1.
- 2. 0 EVALUATION The Code of Feder1l Regul1tions 10 CFR 50.49 requtres licensees to establish a program for qualifying cert1in post-accident monitoring equipment for which specific guidance concerning the types of v1riabl1s 110nitored ts provided in R.G. l.97, Revision 2.
This regulatory guide identifies neutron flux as a Type B variable that provides inform1tion to indicate whether plant safety functions are being accomplished.
The guide tdentiftes Category 1 crtteria for this instrumentation.
The Category l criteria tncludes envtromnental qualification, seismic qu1lific1tion, Class JE power sources, and redundant channels.
Qualification criteria for instrumentation is established based on the safety fu~ction of the syste~ whose variables are being monitored.
The selection criteria for R.G. 1.97 variable qualification category is based upon whether
~~~itoring of system parameters is needed during and following an accident 1nd
.,.".et her subsequent operator actions are dependent on the information provided by this instrumentation.
ir,E 1.~:.,.:.,-j.SS6 report analyzes event scenarios to determine the consequences of neutron flux monitoring unavailability 1nd concludes that the f1ilure of this ir:stru-,er,tation will not prevent the operator from determining reactor power levels. Alternate parameter status will be 1vailable from which reactor po~er ~ay be inferred.
Some alternate indications may require more than one input to determine reactor power.
However, b1sed on the multiple inputs a.a;la~,e ~= the operator, sufficient information will be available upon which to base operational decisions and to conclude that reactivity control has been a:c:-;*,s~e~.
Fu~ther, NED0-31558 contains criteria regarding the range, po~e~ sup~l1es, and qualifications for neutron flux monitoring instrumentation that provide sufficient confidence that the neutron flux monitoring irstr0~e~tatio~ will be available to confirm reactor shutdown fpr a*wide range of events including ATWS.
The BWR Owners Group also stated that for BWR desig~ basis events, recriticality is not a significant contributor to core melt risk for BWR accident scenarios th1t go beyond the design basis.
Based on the BWR Owners Group subm1ttals, the Director of NRR has deter111ined that Category l neutron flux monitoring instrumentation ts not needed for existing 8WRs to cope with LOCA, ATWS, or other accidents that do not result in severe core damage conditions. Instrumentation to inon1tor the progression of core melt accidents 1s best addressed by the current severe accident management program.
Therefore, for existing BWRs, neutron flux inonttoring instrumentation does net need to meet the Category l criteria of R.G. J.97.
Neutron flux monitoring instrumentation, at existing BWRs, needs to 1111et the ne~ criteria proposed by the BWR Owners Group in NED0-31558.
However, new applications for conventional and advanced BWR designs w111 be required to meet the ~.G. l.97 criteria.
Licensees should review their neutron flux 11e>nftoring instrumentation against the criteria of NED0-31558 and confina that they 9eet this criteria. Jf the instrumentation does not 11eet the crfterfa, licensees should aake a coa111itment to meet the criteria and state when this COllllit.ent will be fulfilled. If a conrnitment to the criteria cannot be aade, licensees should 1xplfcttl1 state any deviations from the criteria and provide supporting justiftcatton or alternatives.
The criteria in NED0-31558 includes the use of unfnterruptible and reliable power sources.
The BWR Owners Group and the staff agree that each redundant neutron flux monitoring channel should be powered from a different unfnter-rupt ible power supply (UPS). Therefore, a loss of a single UPS would not cause the loss of both channels of neutron flux 11e>nitoring tnstrW11nt1tton.
As stated in Section 5.2.8 of NE00-31558, each licensee should perfonn a plant-specific evaluation to review power distribution to the neutron flux mo~itoring instrumentation, including recorders.
The intent of this review is to verify that neutron flux monitoring instrumentation power would not be lost during events by load shedding logics or similar schemes or that a single power supply failure would not cause the loss of redundant channels of neutron flux monitoring instrumentation.
The 1icenses for Grand Gulf Nuclear Station Unit land River Bend Station cc~~e*r. 1 icense conditions that require the installation of Category l neutron flux monitoring instrumentation. Since neutron flux is no longer considered to be a Category l variable, the staff will entertain licensee requests for remoial of these license conditions.
The licensees for Nine Mile Point Unit l, Perry Nuclear Power Plant Unit I, ar: ~~=-2 ~ave designated neutron flux as a Type A variable because this i~for~ation is required to permit the operator to take specific manually controlled actions.
These licensees will not be required to upgrade the Qualification of the neutron flux monitoring ;nstrumentation to meet the Category 1 criteria. These licensees should review their Emerg~ncy*Operating Pro:e:u~es (EO~s) to assure that there ;s no plant-specific role for neutron flux rr.onitoring that differs from the evaluat;on in NE00-31558.
If the role of neutron flux monitoring does not differ from the evaluation in the NEDO report, the staff will entertain licensee requests for.removal of neutron flux from their Type A instrument lists.
Since neutron flux monitoring is no longer Category 1 instrumentation, licensees may request the removal of this instrumentation from their post-iCcident monitoring technical specifications if they so desire. licensees wishing to maintain a post-accident 1M>nftoring technical spec1f1catfon on neutron flux monitoring instrumentat;on will be allowed to do so.
Big Rock Point is not bound by the provisions of R.G. J.97, and limerick Generating Station Units I and 2 were granted deviations from the Category l criteria for neutron flux monitoring instrumentation. Therefore, these
_,.. plants do not need to meet the criteria of NED0-31558.
The neutron flux monitoring instrumentation instilled 1t Susquehanna Steam Electric Station Units l and 2 and WNP-2 exceed the criteria of NED0-31558 and, therefore, these plants may take advantage of any relaxation that the new criteria might provide.
3.0 CONCLUSION
Based on its review, the staff concludes that the post-accident neutron flux monitoring instrumentation 1t existing BWRs should..,t the crtt1rta tn NED0-31558.
Licensees should provide 1 consnitment to these criteria and perform a plant-specific power distribution review for neutron flux 110n1tor1ng instrumentation. However, new applications for conventional and advanced BWR designs will be required to 1neet the R.G. J.97 criteria.
Principal Contributor:
B. Marcus Date:
January 13, 1993
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References:
- 1.
Letter from O. G. Eisenhut (NRC) to All Licensees of Operating Reactors, Applicants for Operating Licenses, and Holders of Constructton P1n11ts, "Supplement No. l to NUREG-0737--Requirements for Emergency Response Capability, (Generic Letter No. 12-33),* dated Declllber 17, 1112.
Z.
Regulatory Guide 1.97, Revision 2, *Jnstrumentation for l1ght-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Cond1t1ons During and Following an Accident,* NRC Office of Standards Development, dated December 1980.
- 3.
Letter from R. F. Janecek (BWROG) to T. E. Murley (NRC) *swR Owners' Group Licensing Topical Report Position on NRC Regulatory Guide l.97, Re.is~cn 3 ReQuirements for Post-Accident Neutron Monitoring System" (General Electric Report NED0-31558), dated April l, 1988.
- 4.
Regulatory Guide 1.97, Revision 3, *instrumentation for L1ght-Water-Cooled Nuclear Power Plants to Assess Plant and Environs Conditions During and Following an Accident," NRC Office of Nuclear Regulatory Research, dated May 1983.
S.
Letter from F. J. Miraglia (NRC) to S. O. Floyd (BWROG), *swR Owners' Group Licensing Topical Report Position on NRC Regulatory Guide 1.97, Revision 3 ReQuirements for Post-Accident Neutron Monitoring System*
(General Electric Report NED0-31558), dated January 29, 1990.
- 6.
Letter fro~ G. J. Beck (BWROG) to T. E. Murley (NRC), *Appeal of NRC S:~rf Decisic~ Regarding Upgraded Neutron Flux Monitoring Systems for 81'1°~s. ** dated August 16, 1990.
- 7.
Le:ter fro~ T. E. Murley (NRC) to C. L. Tully (BWROG), *Appeal of NRC Staff Decision Regarding Upgraded Neutron Flux Monitoring* Systems for B*:=.s," dated October 14, 1992.