ML20031B214
| ML20031B214 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/23/1981 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Atomic Safety and Licensing Board Panel |
| Shared Package | |
| ML20031B215 | List: |
| References | |
| TASK-AS, TASK-BN-81-26 BN--81-26, BN-81-26, TAC-59974, TAC-59975, NUDOCS 8110010036 | |
| Download: ML20031B214 (2) | |
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HSilver EHughes 11E!iORAtlDU!! FOR: Atomic Safety and Licensing Board for THI-1 FR0H:
Thomas !!. Novak, Assistant Director for Operating Reactors, Division of Licensing
SUBJECT:
BOARD fl0TIFICATI0tl - THERf!AL SHOCK TO PWR REACTOR PRESSURE VESSELS (BN )
This memorandun is a followup to our memorandun to you dated May 8,1981 (Bf!-81-06) concarning PWR pressure vessel thornal shock. This subject was addressed in part for Ti1I-l in the evaluation of Action Plan Iten II.K.2.13 Thernal licchanical Report (enclosure to letter, J. !!. Cutchin g to TitI-l Board f.1 cabers, dated April 22,1981).
Enclosed are SECY-81-28GA dated September 8,1981; briafing natorial, from the September 15, 1981 Comission briefing on thornal shock; a d a letter
'n report from J. II. Smith (ORNL)to, W. llazelton (NRC) concerning Oconce Unit 1 vessel inspection. This subject was also discussed in detail with the ACRS on September 11,1931.
The conclusion of the staff (as stated in the enclosures) remains that there is no need for immediate.llcensing action based on pressurized thernal shock considerations for any operating reactor. As stated in our August 21, 1981 letter to fiet Ed (attached to SECY-81-286A) and seven o+'icr licensecs, all plants could survive a severe overcooling event for at least another year of full power operation based on the staff's independent review. Ilew-ever, the staff believes that additional action as outlined in the enclosures is warranted now to ensure that risks of vessel failure remain sufficiently low to support continued operation of licensed PWRs.
It should be noted that the enclosed ORNL report identifies the possibility of flaws discovered in the Oconee Unit 1 vessel during erecent inservice inspec-tion. The data is preliminary and has not yet been fully ev luated or con-a firmed by further inspections.
It is expected that the flaws, if confirmed, will be within ASME Code allowable limits.
ogiginal signed by Thonas M. flavak, Assistant Director for Operating Reactors Division of Licensing
Enclosures:
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DISTRIBUTION Docket File HSilver DSnyder ORB #4 Rdg TNovak EHughes Memo. File DEisennut JHard Docket No. 50-289 NRC PDR ECase MJollensten-5 L PDR RJacobs TERA EHyiton NSIC DDilanni MEMORANDUM FOR: Atomic Safety and Licensing Board for TMI-1 I
FROM:
Thomas M. Novak, Assistant Director for Operating Reactors, Division of Licensing
SUBJECT:
BOARD NOTIFICATION. THERMAL SH0CK TO PWR REACTOR PRESSURE VESSELS (BN-81-2 6)
This memoran fum is a followup to our memorandum to you dated May 8,1981 (BN-81-06) concerning PWR pressure vessel thermal shock. This subject was addressed in part for TMI-l in the evaluation of Action Plan Item H.K.2.13 Thermal Mechanical Report (enclosure to letter, J. ft. Cutchin H to THI-l Board members, dated April 22, 1981).
Enclosed are SECY-81-286A dated September 8,1981, briefing material from 3
the September 15, 1981 Commission briefing on thermal shock; briefina material from the September ll,1981 ACRS meeting on thermal shock. and a letter report from J. H. Smith (0RNL) to W. Hazelton (NRC) correrning Oconce Unit 1 vessel inspection.
The conclusion of the staff (as stated in the er. closures) remains that tnere is no need for immediate licensing action based on pressurized thermal shock considerations for any operating reactor. As stated in our August 21, 1981 letter to Met-Ed (attached to SECY-81-286A) and seven other licensee:, all plants could survive a severe overcooling event for at least another year of full power operation bcsed on the staff's independent review. However, the staff believes that additional action es outlined in the enclosures is warranted now to ensure that risks of vessel failure remain sufficiently low to support cnntinued operation of licensed PWRs.
It should be noted that the enclosed ORNL report identifies flaws dis-covered in the Oconee Unit 1 vessel during a recent inservice inspection.
Although it is possible that flaws of this depth and length exist in the THI-1 vessel, the magnitude of these flaws is well within acceptable limits permitted by ASME code and as such, do not present unacceptable risks to public health and safety.
Thomas M. Novak, Assistant Director for Operating Reactors Division of Licensing
Enclosures:
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