ML20244E414

Safety Evaluation Supporting Util post-accident Monitoring Instrumentation Per Reg Guide 1.97 & Generic Ltr 82-33

ML20244E414
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	04/14/1989
From:	NRC
To:
Shared Package
ML20244E400	List: ML20244E414 ML20244E419
References
RTR-REGGD-01.097, RTR-REGGD-1.097 GL-82-33, NUDOCS 8904240470
Download: ML20244E414 (5)

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ENCLOSURE SAFETY EVALUATION REPORT COMMONWEALTH EDISON ZION NUCLEAR POWER STATION UNIT N05. 1 AND 2 COCKET NOS. 50-295 AND 50-304 CONFORMANCE TO REGULATORY GUIDE 1.97

1.0 INTRODUCTION

Commonwealth Edison was requested by Generic Letter 82-33 to provide a report to NRC describing how the post-accident monitoring instrumentation meets the guidelines of Regulatory Guide (R.G.) 1.97 as applied to emergency response facilities. The licensee responded to Item 6.2 of the generic letter on August 1, 1986. Additional information was provided by a letter dated August 24, 1987.

t A detailed review and technical evaluation of the licensee's submittals was performed by EG&G Idaho, Inc., under a contract to the NRC, with general supervision by the NRC staff. This work was reported by EG&G in Technical Evaluation Report (TER), "Conformance to Regulatory Guide 1.97: Zion-1/-2,"

dated July 1988 (attached). We have reviewed this report and concur with the conclusion that the licensee either conforms to, or has adequately justified deviations from, the guidance of R.G. 1.97 for each post-accident ronitoring variable except for the variables accumulator tank level and pressure, neutron flux, abd containment isolation valve position.

2.0 EVALUATION CRITERIA Subsequent to the issuance of the generic lettert the NRC held regional meetings in February and March 1983 to answer licensee and applicant questions and concerns regarding the NRC policy on R.G. 1.97. At these meetin'gs, it was i established that the NRC review would only address exceptions taken to the guidance of R.G. 1.97. Further, where licensees or applicants explicitly state that instrument systems conform to provisions of the regulatory guice, no further staff review would be necessary for those iterns. Therefore, the 8904240470 890414 PDR ADOCM 05000295 P PNu

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review performed and reported by EG&G only addresses exceptions to the l guidance of R. G. 1.97. This safety evaluation addresses the licensee's submittals based on the review policy described in the NRC regional meetings and the conclusions of the review as reported by EG&G.

3.0 EVALUATION We have reviewed the evaluation performed by EG&G contained in the attached TER and concur with its bases and firdings, except for the findings contained in TER section 3.3.11 concerning e) accumulator tank level and pressure. For the remaining items we agree with EG&G's findings that the licensee either confonns to, or has provided an acceptable justification for deviations from the guidance of R.G.1.97 for each post-accident monitoring variable except for the variables b) neutron flux and c) containment isolation valve position.

a) In TER section 3.3.11 EG&G concluded that for the variable accumulator tank level and pressure, the licensee should designate either level or pressure as the key variable to directly indicate accumulator discharge and provide instrumentation for that variable that meets the recommendations of R.G. 1.97 and 10 CFR 50.49. The staff, however, is currently generically reviewing the need for environmentally qualified Category 2 instruments to mcnitor accumulator tank level and pressure.

We will therefore report on the acceptability of this item when the generic review is complete.

b) R.G. 1.97 recommends Category 1 reutron flux instrumental,on to monitor reactivity control. As such, this instrumentation should be environmentally and seismically qualified. The instrumentation provided by tir. ikenset is not environmentally or seismically qualified. The justification provided by the licensee for not fully c.ualifying the neutron flux monitoring instren:entation is that a reactor trip auten.atically ectivates the release of the controi rods at the enset of accident symptoms, before harsh environn. ental conditions occur. The neutron flux scurce and intermediate range instronentation is expected i

t to operate. .The operator is required to initiate emergency boration should rod bottom lights or neutron flux fail to indicate reactor shutdown.

The alternate instrumentation cited by the licensee does not provice necessary.information required for post-accident monitoring in accordance with the regulatory guide. In LOCA situations, monitoring of neutron flux is a direct indication of return to criticality rather than a lagging, indirect indication, as provided by the licensee's proposed instrumentation. Thus, the staff finds the licensee's justification unacceptable.

The licensee should provide neutron flux monitoring instrumentation that is environmentally qualified in accordance with the provisions of 10 CFR 50.49 and R.G. 1.97 and seismically qualified in accordance with the provisions of R.G. 1.100.

c) R.G.1.97 recommends Category 1 instrumentation to monitor the position  :

of all containment isolation valves to verify containment isolation. ..

Based upon the information provided by the licensee, the staff is unable to determine that the recommendations for redundancy, the single-failure  ;

criterion, and environmental qualification have been met.

The licensee listed a group of valves that do not have position indication for series pairs. The licensee states that backup indication is provided by various plant system variables. The licensee should l provide noditional information for the valves listed. This information r should include the basis for no indication of individual valves of series pairs and the use of plant system variables to determine proper vhlve i position.

The licensee stated that all tir operated cr.o solenoid cperated valves fail in the s&fe (closeo) directior en loss of pcwer, thus, position l

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. I status for these valves need only meet Category 3 criteria. The fact that these valves fail shut is not sufficient justification for not qualifying this position indication. A control circuit failure could cause a valve to be open. The operator shculd be able to positively ascertain that the valves are shut.

The staff is unable to determine from the licensee' submittals which valve position switches are located in a mild environment and which ones are not. The licensee should pt ovide infonnation that verifies that all position indicatien switches requiring environmental qualification have i environmentally qualified limit switches.

4.0 CONCLUSION

f>ased on the staff's review of the enclosed TER and the licensee's submittals, we find that the Zion Nuclear Power Station Unit Nos. 1 and 2 design, is acceptable with respect to conformance to R.G. 1.97, Pevision 2, except for the instrumentation associated with the variables a) accumulator tank level and pressure, b) neutron flux, and c) contaircent isolation valve position.

a) The acceptability of instrumentation for accumulator tank level and pressure will remain open pending the outcome of the staff's review of the need for environmentally qualified instrumentation to monitor this  ;

variable. The staff's ccnclusion will be reported on when the generic i review is complete.

b) It is the staff's position that information provided by the neutron flux monitoring instrurrentation is needed by the operator in evaluation of I

proper reactivity control. It is also the staff's position that the licensee stell irstall neutron flux monitoring instrumentation that that is environmentally ard seismically qualified in accordance to 19 CFR 50.49, R.G. 1.97 and R.G. 1.100.

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c) It is the staff's position that information provided by the containment isolation valve position indication instru.nentation rieeds to be accurate to prever.t mismanagement or improper operator action in the post-accident situation. It is also the staff's position that the licensee should either:

1) provide, within 60 days of receipt of this report, additional tiforniation and commitments to resolve the questions on redundancy, tl.0 single failure criterion, and environmental qualification of containnient isolation valve position indication, or

2) install, and have operational, containment isolation valve position incication that is qualified for accident and post-accident environments at the fire? scheduled outage of significant duration, but no later than startup following the second refueling outage 1 after receipt of this report.

An appropriate implementation schedule will be developed by the project manager via discussion with the licensee. Once the schedule is established, the licensee is required to inform the Commission, in writing, of any significant changes in the established completion schedule identifieo ir. the staff's safety evaluation and when the action has actually been completed.

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