ML20093N111

Discusses Acceptability of Midland Reactor Pressure Vessel Anchor Bolts,Per Util & Attached Rept.Expresses Concern Re Rept Sufficiency

ML20093N111
Person / Time
Site:	Midland
Issue date:	02/03/1982
From:	Shewmon P Advisory Committee on Reactor Safeguards
To:	Vollmer R Office of Nuclear Reactor Regulation
Shared Package
ML19258A087	List: IR 05000329/1978020 IR 05000329/1981012 IR 05000329/1982007 IR 05000329/1982009 IR 05000329/1982014 ML19258A086 ML19351C947 ML20093B251 ML20093B495 ML20093B616 ML20093B708 ML20093B747 ML20093B900 ML20093B940 ML20093C001 ML20093C006 ML20093C017 ML20093C025 ML20093C030 ML20093C035 ML20093C068 ML20093C073 ML20093C079 ML20093C082 ML20093C101 ML20093C104 ML20093C108 ML20093C116 ML20093C174 ML20093C189 ML20093C196 ML20093C226 ML20093C231 ML20093C262 ML20093C318 ML20093C324 ML20093C347 ML20093C354 ML20093C374 ML20093C377 ML20093C390 ML20093C394 ML20093C398 ML20093C405 ML20093C440 ML20093C444 ML20093C649 ML20093M884 ML20093M994 ML20093N005 ... further results
References
CON-BX14-017, CON-BX14-17, FOIA-84-96 NUDOCS 8408010183
Download: ML20093N111 (1)

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UNITED STATES "g

NUCLEAR REGULATORY COMMISSION -

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E-ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON. D. C. 20555 February 3,1982 MEMORANDUM FOR

R. H. Vollmer, Director NRR, Division of Engineering FROM:

P. G wmon, Chairman, ACRS Midland Subcommittee

SUBJECT:

ACCEPTABILITY OF MIDLAND RPV ANCHOR BOLTS Reference letter from James W. Cook, Consumers Power Co. to J. G. Keppler, I&E (Region III) dated November 23, 1981,

Subject:

Midland Project Unit No.1, Reactor Pressure Vessel Broken Anc:1or Bolt with attached report.

The attachment to the referenced report carefully shows how the new pro-cedure meets the intent and rules of the ASME PV Code,Section III, Sub-section NF, etc. While this is necessary, I am concerned about its sufficiency.

The bolts originally failed because they were loaded and contained notches such that the stress intensity in the bolt K, exceeded y

that necessary for stress corrosion cracking, K in moist alr.

I suspect they met all the provisions of Section f 5kh Subsection NF right

'up until failure, thus my concern about all these pages which don't address the failure but only the " letter of the law."

The licensee's response to this will be that my concern has already been '

laid to rest by reference 1-5 of their report. As I recall, they have con-cluded that stress corrosion cracking of this sort is not of concern if the ultimate stress is below'200 Ksi.

I believe this is far f'. >m a conservative number.

It is one I would like to see the staff's explicit approval o'f if NRC is accepting it. This will ultimately come in their i

forthcoming guides or rules on failure prevention in bolts, but Midland may want an OL before that.

It is possible that the detensioning talked of in the Midland report is for the hardened sufficient to lower the ' stress intensity below K steel bolts set in concrete in Midland.

However,gkk isn't at all clear y

from the reference report.

I would appreciate assurance that someone on the staff is asking this sort of question and getting answers before the OL request gets to the ACRS for review.

desco, NRR S. Pawlicki, NRR R. C. DeYoung, I&E J. G. Keppler. I&E, Region III V. S. Noonan, NRR g 8 g 83 840718 RICE 84-96 PDR e

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