ML072850067

Oyster Creek September 2007 Evidentiary Hearing - Intervenors Exhibit 53, Letter from Alexander W. Dromerick to John J. Barton, Subject: Clarification of Staff Position on Evaluation of Structural Integrity of Degraded Steel Containment

ML072850067
Person / Time
Site:	Oyster Creek
Issue date:	11/19/1991
From:	Dromerick A NRC/NRR/DLPM/LPD4
To:	J. J. Barton GPU Nuclear Corp
SECY RAS
References
50-219-LR, AmerGen-Intervenor-53, RAS 14370
Download: ML072850067 (3)

Text

U,& iJCLfA REGULJY COMIUWON Citizens Exhibits 53 =4uq CC). lc Docet No. LIU O)-- C-ificial ExhbtW NO.CY-ý-5 e

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UNITED STATES Action Taken: "ADMITTED R *j.T6)WITHDRAWN WASHINGTON. 0I. C. 20555 eo rlar- .--

November 19, 1991 DOCKETED USNRC Docket No. 50-219 October 1, 2007 (10:45am)

OFFICE OF SECRETARY RULEMAKINGS AND ADJUDICATIONS STAFF Mr. John 3. Barton, Vice President and Director GPU Nuclear Corporation Oyster Creek Nuclear Generating Station Post Office Box 388 Forked River, New Jersey' 08731

SUBJECT:

CLARIFICATION OF STAFF POSITION ON EVALUATION OF STRUCTURAL INTEGRITY OF A DEGRADED STEEL CONTAINMENT (TAC N0A79166)

References:

1. Letter to J. J. Barton from A. W. Dromerick providing the subject staff's position dated September 3, 1991.

2. Letter'to NRC from GPU Nuclear Corporation providing the-response to staff's position dated October 9, 1991.

In a letter of October 9, 1991 (Reference 2), GPU Nuclear Corporation (GPUM) provided responses to the staff position on the evaluation *of the structural integrity of a degraded steel containment. It appears from the responses that GPUN differs with the staff's position, specifically on the application of ASME subsection NE-3213.10. Enclosed is the staff's reviei of GPUN's response. It clarifies the staff's position and requ-ires GPUN to provide additional information to aid in a final resolution of staff's concerns.

We request that the information be provided within 30 days of receipt of this letter. If you have any questions regarding this request, please contact me.

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Mr. John J. Barton The requirements of this letter affect fewer than 10 respondents, and therefore, are not subject to Office of Management review under P.L.97-511, Sincerely, Is/

Alexander W. Dromerick, Sr. Project Manager Project Directorate 1-4 Division of Reactor Projects - I/1I Office of Nuclear Reactor Regulation

Enclosure:

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NOT716

REVIEW OF GPUN'S RESPONSE OF OCTOBER 9, 1991 RELATED TO THE STAFF',S POSITION ON EVALUATION OF DEGRADED STEEL CONTAINMENT AT OYSTER CREEK The staff has reviewed GPU Nuclear Corporation's (GPUN) response of October 9, 1991 to the staff's position on the evaluation of the structural integrity of.

a degraded steel containment.. It is to be noted that this staff position is to be applied generically in the'evaluation of steel containments which are degraded, not specifically to the Oyster Creek steel drywell. The staff's position is based on technical criteria that conform to the spi.rit and intent of ASME subsection NE-3213.10. NE is. the design part of the ASME code and cannot be directly applied to the situation of inservice degradation without the exercise of engineering judgment. By considering the corroded area as equivalent to a-discontinuity as indicated in ME-3212.10, great caution must be exercised. It should be understood that the discontinuity as created by corrosion is not the same as the "designed" discontinuity such as a change.

in shell thicknesses, the presence of a bracket or a penetration as envisioned in the code. The basic characteristic of the discontinuity due to corrosion is irregularity, e.g. variation in thickness and extent of.corroded areas..,..

In view o~f the above observation, the ME 3312.10 stipulation cannot be applied

• indiscriminately to a corroded steel, containment. NE-3312.1O..:.specifies the limit of the discontinuity region in which the stresses can b-.greater than. 1.1 Smc. The code does not specify the outside limit of the region which is contiguous to and supports the discontinuity and in which the stresses vary from 1.1 Smc to 1.0 Smc. This -should be expected because this outside limit varies with the configuration of the discontinuity and the loading. Therefore, the lack of specific stipulation in the code in this respect should be understood and should notlbe construed to allow the stress limit of 1.1 Smc to be applied universally throughout the containment shell. The staff position is not, in any way, more restrictive than the stipulation in the ASME Code.

The staff is well aware of the extensive examinations and analysis performed on the Oyster Creek drywell as reported by GPUN. GPUN has repeatedly claimed that the Oyster Creek drywell has been examined thoroughly and the condition of the drywell is fully understood with a 95% confidence level. On the basis of this claim, the staff has requested OPUN to determine the extent of each corroded area. The staff is not requesting any additional physical examination.

However, on the basis of the information available, GPU.N should present in a figure the known areas of corrosion with the critical stresses (general primary membrane stress or local primary membrane stress) identified. The purpose of such an action is to determine the behavior of the drywell especially at and around the corroded areas. By comparing the calculated stresses of the drywell shell at and around corroded areas with the code allowables the staff can reasonably determine the adequacy of the licensee's proposed actions.

S.