ML19256E418
| ML19256E418 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/26/1979 |
| From: | Rubenstein L Office of Nuclear Reactor Regulation |
| To: | Parris H TENNESSEE VALLEY AUTHORITY |
| References | |
| NUDOCS 7911050178 | |
| Download: ML19256E418 (4) | |
Text
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OCT 2 61979 Docket Nos: 50-327 and 50-328 Mr. H. G. Parris Manager of Power Tennessee Valley Authority 500A Chestnut Street Tower II Chattanooga, Tennessee 37401
Dear Mr. Parris:
SUBJECT:
ENVIRON. MENTAL QUALIFICATION 0F REACTOR COOLANT TEMPERATURE DETECTORS AND CONTAINMENT PRESSURE TRANSMITTERS - SEQUOYAH The environnental qualification for certain Westinghouse-supplied instrumentation is described in WCAP-9157 " Environmental Qualif tion of Safaty-Related Class IE Process Instrumentation." Your application for a license to operate the Sequoyah Plant references WCAP-9157 as a basis for the acceptance of the environ-mental qualification of this instrumentation. The regulatory staff has found that additional information is needed to complete its review of WCAP-9157.
Westinghouse Electric Corporation has agreed to provide the requested information in a timely manner except for three areas:
(1) the qualified life of resistance temperature detectors (RTDs) to be used to measure the temperature of reactor coolant; (2) qualification of field connections for these temperature detectors; (3) qualification of remote bellows sensing pressure transmitters to be used to measure pressure of the containment atmosphere. Acceptable information for these three areas must be provided for our review and approval prior to the issuance of a license to operate your plant. Since resolutha of these matters may not be completed with Westinghouse within the remaining licensing review schedule estimated for your plant, we will require that resolution of the staff's concerns stated below be completed on your application.
The Westinghouse evaluation of the qualified life of the resistance temperature detectors (Section 2.2 of WCAP-9157) is unacceptable because the assumed post-accident fission product source term is too small and the assumed post-accident operating time is too short. Guidelines for calculating acceptable qualified life in a radiation environment follow.
A.
The total integrated exposure to be simulated in qualification tests should be the sum of the calculated integrated exposure during normal plant opera-tion and the calculated integrated exposure during post-accident plant operation.
B.
The fission product source term for calculating exposure during post-accident operation should correspond to loss-of-coolant-accident (LOCA) conditions with a release of 100% of the noble gases, 50% of the iodines, and 1% of the emaining fission products generated in the equilibrium core.
1254 306 7 911050 /7 $ h
Mr. H. G. Parris OCT 2 61979 C.
Post-accident exposure for RTDs should be based on the higher of two exposures calculated by assuming (1) an instantaneous release of fission products from the fuel to the containment atmosphere, and (2) an instantaneous release from the fuel to the reactor coolant without subsequent release to the containment.
D.
Post-accident operation time for the narrow-range resistance temperature detectors should be the sisn of the longest time required for reactor trip in any anticipated operational occurrence or design basis accident plus a margin of one hour for uncertainties in predicting the time.
E.
Post-accident operation time for the wide-range resistance temperature detectors should consider the environmental conditions for an interval of 100 days following the accident, unless a shorter time can be justified.
(Since the post-accident operation time used in qualification tests described in WCAP-9157 is less than 100 days, you should provide justification to show that extending the test to 100 days would not significantly affect instrument performance or accuracy for this period).
WCAP-9157 does not include qualification of electrical connections used in the installation of resistance temperature detectors because these field connections are not made by Westinghouse. Justification for your conclusion that field connections will perkrm acceptably in the post-accident environment is needed.
The qualification test of the remote bellows sensing pressure transmitter resulted in an anomalous pressure spike above the test chamber pressure (Section 6-6 of WCAP-9157 ). The test results are unecceptable to the staff because the indicated pressure does not meet the acceptance criteria for instrument accuracy and anomalous indications, such as the pressure spike, are contrary to the requirements of Section 4 of IEEE-279-1971, "IEEE Criteria for Protection Systems for Nuclear Power Genera-
. ting Stations."
It is concluded in WCAP-9157 that this pressure spike is attribut-able to the smallness of the test chamber and that the spike would not occur in the large containment. The discussion in WCAP-9157 of the cause of the pressure spike in the test and the assurance of its absence in the plant is inadequate. Additional tests or analyses are needed to demonstrate that this pressure transmitter is acceptable.
Please amend your application to provide the following additional information.
1.
Results of calculations using the guidelines in this letter to determine acceptable qualified life of resistance temperature detectors to be used to measure reactor coolant temperatur2.
2.
Results of tests or analyses to demonstrate acceptable environmental qualificaticn of field connections for resistance temperature detectors to be used to measure reactor coolant temperature.
1254 307
Mr. H. G. Parris OCT 2 6197E 3.
Results of tests or analyses, in addition to those in WCAP-9157, to demonstrate acceptable environmental qualification of pressure transmitters to be used to measure containment pressure.
This information is needed by November 7,1979 in order to meet our schedule for review and approval of your application for an operating license.
If you cannot meet this date, please inform us within two weeks from the date of receipt of this letter of a date you will submit the requested information.
If you desire clarification of the technical information requested in this letter please call Tom Dunning on (301) 492-7383.
Sincerely, WS. (LTdQ Lester S. Rubenstein, Acting Chief Light Water Reactors Branch No. 4 Division of Project Management cc:
See next page I2S4 308
Tennessee Valley Authority OCT 261979 7
ccs:
Herbert S. Sanger, Jr. Esq.
General Counsel s==
Tennessee Valley Authority p..
400 Commerce Avenue hj:
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Knoxville, Tennessee 37902 Mr. E. G. Beasley Tennessee Valley Authority 400 Commerce Avenue W10Cl31 C Knoxville, Tennessce 37902 ge.
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Mr. Michael Harding T
Westinghouse Electric Corporation P. O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. David Lambert Tennessee Valley Authority 400 Chestnut Street Tower II Chattanooga, Tennessee 37401 p'-
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