ML20012D091
| ML20012D091 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 02/02/1990 |
| From: | Marcus B Office of Nuclear Reactor Regulation |
| To: | NRC |
| Shared Package | |
| ML20012D089 | List: |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 9003260444 | |
| Download: ML20012D091 (1) | |
Text
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ENCLOSURE 1 l
0 February 2, 1990
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l NOTE Tot BWR Project Managers
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FROM:
Barry S. Marcus Instrumentation and control Systems Branch i
Division of Systems Technology 1
SUBJECT!
POST-ACCIDENT NEUTRON FLUX MONITORING FOR BWRS Reference 1)
BWR Owners' Group letter (R. F. Janecek) to NRC (T. E. Murley), "BWR Owners' Group Licensing Topical Report " Position on NRC Regulatory Guide 1497, Revision 3 Requirements for Post-Accident Neutron Monitoring System" (General Electric Report NEDO-31558), April 1, 1988.
r Regulatory Guide (R.G.) 1.97 and 10 CFR 50.49 require that neutron flux be monitored by Category 1 instrumentation.
The staff has allowed BWRs to operate with existing instrumentation until instrumentation was developed that conforms to the requirements of R.G. 1.97 and 10 CFR 50.49.
Instrumentation that meets the requirements of the R.G. 1.97 and 10 CFR 50.49 is now available.
The Boiling Water Reactor Owners' Group (BWROG) submitted Reference 1 for staff review.
The attached letter and SER finds the BWROG position unacceptable.
Therefore, all licensees must install neutron flux monitoring instrumentation that conforms to the requirements of R.G.
1.97 and 10 CFR 50.49.
It is requested tnat the BWR Project Managers forward.
a copy of the attached letter and SER to the BWR licensees.
The Project Managers should reconfirm, with the licensees, the schedule for implementation of neutron flux monitoring instrumentation that ineets the requirements of R.G. 1.97 and 10 CFR 50.49.
If you nave any question regarding the above information, please contact me on 49-20776.
9003260444 900316 PDR ADOCK 05000354 Barry S. Marcus P
N 'O Instrumentation and Control Systems Branch Division of Systems Technology i
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January 29, 1990 Mr. Stephen D. Floyd, Chairman BWR Owners' Group Carolina Power and Light 411 Fayetteville Street i
Raleigh, NC 27602 i
Dear Mr. Floyd:
1
$UBJECT:
BWR OWNER $' GROUP LICEN$!NG TOPICAL REPORT "P051T10N ON NRC REGULATORY GUIDE 1497 REY!$10N 3 REQUIREMENTS FOR POST-i ACCIDENTNEUTRONMONIt0RINGSYSTEM"(GENERALELECTRICREPOR l
NED0-31558)
References:
1)
BWROwners'Groupletter(R.F.Janecek)toNRC(T.E.
Murley), "BWR Dwners' Group Licensing Topical Report j
" Position on NRC Regulatory Guide 1.97, Revision 3 Requirements for Post-Accident Neutron Monitoring System' (GeneralElectricReportNED031558), April 1,1988.
2)
BWR Owners' Group letter (D. N. Grace) to MRC (T. T.
l Martin), "BWR Owners' Group Licensing Topical Report
" Position on NRC Regulatory Guide 1.97, Revision 3 Requirements for Post-Accident Heutron Monitoring System" (General _iectricReportNEDO31558), June 13,1988.
Reference 2 requested that the staff expedite its review of Reference 1.
Reference 1 submitted the BWR Owners' Group (BWROG) Licensing Topical Report (LTR) for staff review and approval.
The LTR proposed functional criteria for post-accident neutron flux monitoring as an alternative to the Category 1 recommendations specified in Regulatory Guide (R.G.) 1.97.
Based on our review the staff concludes that a Category 1 designetion, and associated lower ran,ge for neutron flux monitoring equipment is appropriate.
Therefore, the proposed LTR NED0-31558 is unacceptable and the neutron flux monitoring equipment must be environmentally qualified to comply with 10CFR50.49.
If you have any que'stions regarding the above information, please contact Barry Marcus, of py staff on 49-20776.
Sincerely, l
Frank J.
reglia, Associate Director Jggy A'
p' for Inspection and Technical Assessment (f
Office of Nuclear Reactor Regulation i
Enclosure:
SER cc w/ enclosure:
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ENCLOSURE 2 i
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j SAFETY EVALUATION REPORT BWR06 LICENSING TOPICAL REPORT NE00-31558.
l POSITION ON REGULATORY GUIDE 1.97, j
REQUIREMENTS FOR POST-ACCIDENT NEUTRON FLUX MONITORING SYSTEM
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1.0 INTRODUCTION
4 By letter dated June 13, 1988, the Boiling Water Reactor Owners' Group (BWROG) requested that the staff expedite its review of BWROG Licensing Topical Report (LTR)NED0-31558"PositiononNRCRegulatoryGuide(R.G.)1.97, Revision 3 Requirements for Post-Accident Neutron Monitoring System", submitted by letter events wh ost ccide t neu r ux oigis na n ig b
required, the effect of neutron flux monitoring instrumentation failure, and proposed functional criteria based on the event analysis.
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2.0 BACKGROUND
The following is a chronology of events for neutron flux monitoring as related to R.G. 1.97:
In December 1980 R.G.1.97, Revision 2, was issued recommending that Category 1 neutron flux monitoring instrumentation be used to monitor reactivitycontrolinboilingwaterreactors(BWRs).
In March 1983, based on a number of surveys within the nuclear power industry it was concluded, by the staff, that existing neutron flux monitoring instrumentation that was available to the industry did not confom to the criteria of R.G.1.97.
However, the staff was informed that instrumentation to confom to the criteria of R.G.1.97 was under dsvelopment.
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Beginning February 1985, with the issuance of the first R.G.1.97 Safety EvaluationReports(SERs),thestaffacknowledgedthatfullyqualified l
neutron flux monitoring systems were not available and instructed i
applicants and licensees to follow industry development and install qualified neutron flux monitoring systems when they became available.
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The SERs also included acceptance of existing neutron monitoring systems j
for interim use until fully qualified neutron flux monitoring systems l
j became available.
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Early in 1987, the staff was infomed that fully qualified neutron flux monitoring systems were now available to the nuclear power industry.
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Beginning in December 1987, R.G. 1.97 SERs acknowledged that industry had developed neutron flux monitoring systems that meet the R.G. 1.97 criteria and instructed applicants and licensees to evaluate these newly developed systems and install neutron flux monitoring instrumentation l
which complies with the Category 1 criteria of R.G. 1.97.
The SERs also included acceptance of existing neutron flux monitoring systems for interim use until fully qualified neutron flux monitoring systems were installed.
R.G. 1.97 recommends Category I neutron flux monitoring instrumentation to monitor reactivity control during post-accident situations.
R.G. 1.97 specifies neutron flux as a key variable for detemining the accomplishment of reactivity control because it is a direct measurement and not an indirect lagging indication.
The regulatory guide specifies that Category 1 systems should be environmentally qualified.
10 CFR 50.49 explicitly references this-regulatory guide and therefore requires that all Category 1 equipment shall be environmentally qualifted.
Existing installed neutron flux monitoring instrumentation typically do not meet these environmental qualification requirements for detectors, cables, and detector drive mechanisms. Some existing systems art not powered by Class IE power supplies.
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i R.G.1.97 recommends that the neutron flux monitoring instrumentation be capable of monitoring a range of 10'0% to 100% full power.
Initiating and l
post reactor shutdown events could involve environmental conditions more extreme than the conditions the typical existing neutron flux monitoring instrumentation was designed to operate in. Neutron flux monitoring instrumentation capable of monitoring readings down to the 104% power level must be able to operate satisfactorily in these extreme environmental conditions. The instrumentation must be reliably in place insnediately after
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initial shutdown, and be fully operable for an extended period of time, i.e..
l in the order of six hours.
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3.0 EVALUATION The LTR provides a discussion of BWR safety analyses relevant to. post-accident neutron flux monitoring instrumentation requirements and uses the results of I
the analyses to establish functional design criteria. These criteria include several deviations from the recomendations of R.G.1.97.
Among these deviations is a proposed " alternate" requirement for the range recomendation of the neutron flux monitoring system (LTR Section 5.2.1), reducing the R.G.
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1.97 recomendations of 10-6% to 100% power to an " alternate" of 1% to 100%
power. This in effect would eliminate any requirement (for this purpose) for the source range monitor (SRM) and intermediate range monitor (IRM) instruments.
The LTR justifies this alternate requirement by examining representative extreme events selected from the range of FSAR and ATWS events.
The analyses and related considerations such as the availability of alternate monitoring equipment (e.g., control rod position indication or boron concentration measurements)arebasedonanticipatedconditionsresultingfromstandard j
event analyses. These might nonnally be considered as reasonably comprehensive for, e.g., FSAR design bases analyses. However, at least some of the instrumentation recomendations of R.G.1.97 were intended to cover a wider range of possibilities, including conditions not necessarily to be anticipated by following the usually clearly defined paths of standard event
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analyses. In particular, the proposed elimination of the 10-6% to 1% power I
portion of the range would delete a primary purpose of the post-accident neutron flux monitoring instrumentation.
This purpose was intended to provide, I
with maximum forewarning time, operator information (via indications of deviations from normal post shutdown flux levels) warning of possible post event approaches or return to a critical state.
This might be under circumstances which would involve reactor states and evolving events and conditions not anticipated from analyses following normally considered event i
scenarios.
It would thus be virtually impossible to either predict or i
demonstrate the implausibility of such event paths and resulting conditions with assurance.
Therefore, while not disputing the analyses or results presented in the LTR, it must be concluded that they do not address the above conceptual basis that set the low power range recommendations of R.G. 1.97.
The required power level issetbyexpectedfluxlevelsexistingforsomeextendedperiodoftime(in the order of several hours) after shutdown and for reactivity status and neutron (insta' led and operational) source levels resulting from normal rapid
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shutdown from operation. The normal flux levels serve as a base for observable devi
, of anomalous reactivity states in the (unknown) anomalous i
events indicated aoove.
10CFR50.49 requires that certain post-accident monitoring equipment (Category 1 and 2) be environmentally qualified.
Therefore, based on the above evaluation,
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the staff continues to conclude that the Category 1 designation is appropriate and neutron flux monitoring equipment must be environmentally qualified to comply with 10CFR50.49.
To provide suitable interpretation, neutron flux monitoring detectors internal to the pressure vessel (e.g., in standard SRM locations) appear to be preferable, but neutron flux monitoring detectors external to the pressure vessel (e.g., in the drywell) could be considered. The chosen neutron flux monitoring system, should be operational during degraded core cooling conditions leading to some fuel clad failure, but not significant clad or fuel melting.
Environmental conditions external to the pressure vessel to be i
considered should include high temperature, high humidity, radittion, and possible flooding, associated with external LOCA conditions. Fire conditions which might affect control rod actuation and/or position readout and thus require the use of the low range neutron flux monitoring instrumentation ' '
should also be considered.
Because the functional criteria proposed in the LTR does not meet the requirements of 10 CFR 50.49, the LTR functional criteria is unacceptable.
The staff has been infomed that industry has developed and made available, to the nuclear power industry, at least two different wide range neutron flux monitoring systems that satisfy all the Category 1 criteria of R.G. 1.97.
Therefore, it is the staff's position that BWR licensees should evaluate these newly developed systems and install neutron flux monitoring instrumentation which fully complies with the Category 1 criteria of R.G. 1.97.
4.0 CONCLUSION
Based on our review, the staff concludes that, as an alternative to the Category 1 criteria of R.G. 1.97, the propcsed LTR NED0-31558 functional criteria for post-accident neutron flux monitoring instrumentation is unacceptable, it is also concluded that the proposed alternate range requirement of LTR Section 5.2.1, 15 to 1005 power does not meet the intent of R.G. 1.97, and is therefore unacceptable. The range of neutron flux monitoring instrumentation 4
should remain 10 % to 1001 power.
It is the staff's position that BWR licensees should install neutron flux monitoring instrumentation that fully complies with the Category 1 criteria of R.G. 1.97 and 10 CFR 50.49.
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Mr. Steven E. Miltenberger Hope Creek Generating Station Public Service Electric & Gas Co.
CC' M. J. Wetterhahn, Esquire Mr. Scott B. Ungerer, Manager Cor.ner & Wetterhahn Joint Generation Projects Department Suite 1050 Atlantic Electric Company 1747 Pennsylvania Avenue Post Office Box 1500 Washington, D.C.
20006 Pleasantville, New Jersey 08232 R. Fryling, Jr., Esquire Law Department - Tower SE 80 Park Place Newark, New Jersey 07101 Resident Inspector U.S. Nuclear Regulatory Comission P.O. Box 241 Hancocks Bridge, New Jersey 08038 Mr. S. LaBruna Vice President - !!uclear Operations Nuclear Department P.O. Box 236 Hancocks Bridge, New Jersey 08038 Mr. J. J. Hagan General Manager - Hope Creek Operations Hope Creek Generating Station P.O. Box 236 Hancocks Bridge, New Jersey 08038 Mr. B. A. Preston, Manager Licensing and Regulation Nuclear Department P.O. Box 236 Hancocks Bridge, New Jersey 08038 Regional Administrator, Region i U.S. Nuclear Regulatory Comission 475 Allendale Road King of Prussia, Pennsylvania 19406 Dr. Jill Lipoti, Ph.D hew Jersey Department of Environmental Protection Radiation Protection Program State of New Jersey CN 415 Trenton, New Jersey 08625 J