ML20011E780
| ML20011E780 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 02/08/1990 |
| From: | Black S Office of Nuclear Reactor Regulation |
| To: | Kingsley O Tennessee Valley Authority |
| Shared Package | |
| ML20011E781 | List: |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097, TAC-51073, TAC-51074, TAC-51075 NUDOCS 9002220462 | |
| Download: ML20011E780 (3) | |
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5 NUCLEAR REGULATORY COMMISSION l'.-3' WASHINoTON, D. C. 20666 l
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February 8, 1990
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Docket Nos.
50-259, 50-260 and 50-296 Mr. Oliver D. ' Kingsley, Jr.
i Senfor Vice President, Nuclear Power
. Tennessee Valley Authortty CN 38A Lookout Place 1101 Market Street Chattanooga, Tennestee-37402-2801
Dear Mr. Kingsley:
SUBJECT:
EMERGENCY RESPONSE CAPABILITY - CONFORMANCE TO REGULATORY GUIDE 1.97, REVISION 3 (TAC NOS. 51073,51074,51075)
REFERENCES:
- 1) Letter from S. Black (NRC) to S. A. White (TVA), " Request for Compliance with the Guidelines of Regulatory Guide 1.97 "
t dated June 23, 1988.,
'2) Letter from R. Gridley (TVA) to NRC, Response to NRC's Safety Evaluation Report on Regulatory Guide 1.97 " dated August 23, 1988.
- 3) Letter from S. Black (NRC) to 0. D. Kingsley (TVA), "TVA's August 23,.1988 Response to NRC Safety Evaluation on J
Browns Ferry Compliance to Regulatory Guide 1.97, dated January 19, 1989.
In response to the staff's Safety Evaluation (Reference 1), the Tennessee Valley. Authority (TVA or the licensee) submitted a. request for deviations from the recommendations of Regulatory Guide 1.97 relating to the following variables: core spray flow, low pressure coolant injection flow, residual heat removal __(RHR) system flow, RHR heat exchanger outlet temperature, cooling
-water temperature to engineered safety feature (ESF) system components, cooling water flow to ESF system components, emergency ventilation damper position and
-neutron flux. - The issues involved with core spray flow, low pressure coolant injection flow, RHR system flow, and emergency ventilation damper position have been previously resolved (Reference 3).
s-We have reviewed the remaining issues and all issues are now resolved.
The staff has rejected the BWROG position on neutron flux monitoring (see Enclo-I sure-1, letter from F. Miraglia to S. Floyd dated January 29,1990) and will require TVA to install instrumentation which complies with the Category 1 L
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criteria of Regulatory Guide 1.97.
Please also refer to our enclosed supple-mental Safety. Evaluation with its attachment (Enclosure 2).
This completes the staff's review of Regulatory Guide 1.97 issues covered under TAC Nos. 51073,
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51074, and 51075.
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Mr. Oliver D. Kingsley, Jr. _
If you have any-questions contact David H. Moran, Project Manager at (301).4924766.
Original' signed by Suzanne C. Black, Assistant Director-for Projects
.3 TVA Projects Division Office of Nuclear Reactor Regulation
Enclosures:
1.
LetterfromF.Miraglia(NRC)to S. Floyd (BWROG) dated January 29, 1990 i
2.
Supplemental Safety Evaluation cc w/ enclosures:
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Mr. Oliver D. Kingsley, Jr. cc:
General Counsel Chaiman, Limestone County Commisston Tennessee Valley Authority P. O. Box 18B 400 West Summit Hill Drive Athens, Alabama 35611 ET 11B 33H Knoxville, Tennessee 37902 Claude Earl Fox, M.D.
State Health Officer-Mr. F. L. Moreadith State Department of Public Health Vice President, Nuclear Engineering State Office Building Tennessee Valley Authority Montgomery, Alabama 36130 400 West Summit Hill Drive WT 12A 12A Regional Administrator, Region II Knoxv111a, Tennessee 37902 U.S. Nuclear Regulatory Commission 101 Marietta Street, N.W.
Dr. Mark 0. Medford Atlanta, Georgia 30323 Vice President and Nuclear Technical Director Mr. Danny Carpenter Tennessee Valley Authority Senior Resident Inspector 6N 38A Lookout Place Browns Ferry Nuclear Plant Chattanooga, bnnessee 37402-2801 U.S. Nuclear Regulatory Commission Route 12 Box 637 Manager, Nuclear Licensing Athens, Alabama 35611 and Regulatory Affairs Tennessee Valley Authority Dr. Henry Myers Science Advisor SN 157B Lookout Place Comittee on Interior Chattanooga, Tennessee 37402-2801 and Insular Affairs U.S. House of Representatives Mr. O. J. Zeringue Washington, D.C.
20515 Site Director Browns Ferry Nucis :.r Plant Tennessee Valley Authority Tennessee Valley Authority Rockville Office P. O. Box 2000 11921 Rocleille Pike Decatur, Alabama 35602 Suite 402 Rockville, Maryland 20852 Site Licensing Manager Browns Ferry Nuclear Plant Tennessee Valley Authority P. O. Box 2000 Decatur, Alabama 35602 Mr. G. Campbell Plant Manager Browns Ferry Nuclear Plant Tennessee Valley Authority P, O. Box 2000 Decatur, Alabama 35602
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January 29, 1990 Mr. Stephen D. Floyd, Chairman BWR Owners' troup Carolina Power and Light 411 Fayetteville Street, -
l Raleigh, NC 27602
Dear Mr. Floyd:
$UBJECT:
8WR OWNER 5' GROUP LICEN5!NG TOPICAL REPORT " POSITION QM NR RESULATORY GUIDE 1.97 REV!$!0N 3 REQUIREMENTS FOR POST.
ACCIDENTNEUTRONMON!t0RINGSYSTEM"(GENERALELECTRICR NE00-31558) l l
References:
1)
BWR Owners' Group letter (R. F. Janecek) to NRC (T. E.
Murley), "BWR Owners' Group Licensing Topical Report t
" Position on NRC Regulatory Guite 1.97, Revision 3 Requirements for Post. Accident Neutron Monitoring System" (GeneralElectricReportNED031558), April 1,1988.
2)
BWR Owners' Group letter (D. N. Grace) to NRC (T. T.
Hartin), "BWR Owers' Group Licensing Topical Report
" Position on NRC Regulatory Guide 1.97 Revision 3 Requirements for Post-Accident Neutron Monitoring System" (GeneralElectricReportNED031558), June 13,1988.
Reference 2 requested that the staff expedite its review of' Reference 1.
t Reference 1 submitted the BilR Owners' Group (SWROG) 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 I
reconnendations specified in Regulatory Guide (R.G.) 1.97, i
Based on our review the staff concludes that a Category 1 designation, and associated lower ran,ge for neutron flux monitoring ecuipment is appropriate.
l Therefore, the proposed LTR NE00-31558 is unacceptable and the neutron flux monitoring equipment must be environmentally qualified to comply with 10CFR50.49.
l Barry Marevs. y qu'estions regarding the above information, please If you have an of py staff on 49-20776.
Sincerely, t
Frank J.T0 reglia, Associate Director for Inspection and Technical Assessment l
Office of Nuclear Reactor Regulation I
Enclosure:
SER cc w/ enclosure:
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ENCLOSURE l.
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$AFETY EVALUATION REPORT l
BWR04 LICER$1NG TOPICAL REPORT NE00-31558.
Pd5!T!0NONREGULATORYGUIDE1.97 l
REQUIREMENTS FOR POST-ACCIDENT NEUTRON FLUX MONITORING SYSTEM l
i 1.0 INTR 000CT!QN By letter dated June 13, 1988, the toiling Water Reactor Owners' Group (BWR0G) requested that the staff expedite its review of BWR06 Licensing Topical Report (LTR)NE00-31558"PositiononNRCRegulatoryGuide(R.G.)1.97, Revision 3 Requirements for Post-Accident Neutron Monitorfng System", submitted by letter dated April 1, 1988.
The LTR provides an event analysis of selected postulated events where post-accident neutron flux monitoring instrumentation might be required, the effect of neutron flux monitoring instrumentation failure, and proposed functional criteria based on the event analysis.
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 reconnending that Category 1 nA tron 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 conform to the criteria of R.G. 1.97.
However, the staff was inforined l
that instrumentation to conform to the criteria of R.G.1.97 was under development.
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4 Beginning February 1985, with the issuance of the first R.G.1.97 Safety Evaluation Reports (SERs), the staff acknowledged that fully qualified neutron flux monitoring systems were not available and instructed applicants and licensees to follow industry development and install qualified neutron flux monitoring systems when they became available.
The SERs aise included acceptance of existing neutron monitoring systems for interim use until fully qualified neutron flux monitoring systems became available.
Early in 1987, the staff was inforwed that fully qualified neutron flux monitoring systems were now available to the nuclear power industry.
Beginning in December 1987, R.G.1.97 SERs acknowhdged 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 instrumentatiun 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 recomends Category 1 neutron flux monitoring instrumentation to monitor reactivity control during post-accident situations.
R.G. 1.97 I
specifies neutron flux as a key variable for determining 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 50.4g explicitly references this regulatory guide and therefore requires that all Category 1 equipment shall be environmentally qualified.
Existing installed neutron flux monitoring instrumentation typically do not meet these environmental qualification requirements for detectors, cables, and detector drive mechanisms.
Some existing systems are not powered by class IE power supplies.
3 4
.l R.G.1.97 reconnends that the neutron flux monitoring instrumentation be capable of monitoring a range of 10-65 to 2005 full power.
Initiating and post reactor shutdown events could involve environmental conditions more extreme than the conditions the typical existing neutron flux monitoririg instrumentation was designed to operate in. Neutron flux monitoring l
instrumentation capable of monitoring readings down to the 10-65 power level must be able to operate satisfactorily in these extreme environmental conditions. The instrumentation must be reliably in place inanediately after initial shutdown, and be fully operable for an extended period of. time. i.e.,
in the order of six hours.
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 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.
1.97 recomendations of 10 % to 1001 power to an " alternate" of 1% to 100%
1 power.
This in effect would eliminate any requirement (for this purpose) for the source range monitor (SRM) and interwediate range monitor (IRM) instruments.
l l
The LTR justifies this alternate requirement by examining representative extreme events selected from the range of FSAR and ATWS events.
The analyses l
and related considerations such as the availability of alternate monitoring l
equipment (e.g., control rod position indication or boron concentration l
measurements) are based on anticipated conditions resulting from standard l
event analyses.
These might normally be considered as reasonably comprehensive for, e.g., FSAR design bases analyses.
However at least some of the instrumentation reconnendations 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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4 analyses.
In particular, the proposed elimination of the 10-61 to 11 power portion of the range would delete a primary purpose of the post-accident neutron flux monitoring, instrumentation. This purpose was intended to provide, 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 scenarios.
It would thus be virtually impossible to either predict or 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 is set by expected flux levels existing for some extended period of time (in the order of several hours) after shutdown and for reactivity status and neutron (installed and operational) source levels resulting from normal rapid shutdown from power operation.
The ncrmal flux levels serve as a base for observable deviations of anomalous reactivity states in the (unknown) anomalous events indicated above.
10CFR50.49 requires that certain post accident monitoring equipment (Category 1 and 2) be environmentally qualified.
Therefore, based on the above evaluation, 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 tothepressurevessel(e.g.,instandardSRMlocations)appeartobe 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 t
1 considered should include high temperature, high humidity, radiation, and possible flooding, associ,ated with external LOCA conditions.
Fire conditions which might affect contr'ol rod actuation and/or position readout and thus require the use of the low range neutron flux monitoring instrumentation i
should also be considered.
8ecause 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 informed that industry has developed and made available, to the nuclear power industry, at least two different wide range neutron flux monito' ring systems that satisfy all the Category 1 criteria of R.G.1.97.
Therefore, it is the staff's position that n't licensees should evaluate these newly developed systems and install neutron flsx monitoring instrumentation which fully complies with the Category 1 crite *1a 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 NE00-31558 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 1001 power does not meet the intent of R.G. 1.97, and is therefore unacceptable.
The range of neutron flux monitoring instrumentation should remain 10-65 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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