ML20209F410
| ML20209F410 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Diablo Canyon |
| Issue date: | 02/11/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML082410749 | List:
|
| References | |
| FOIA-86-197 IEB-80-11, NUDOCS 8704300281 | |
| Download: ML20209F410 (4) | |
Text
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ENCLOSURE SAFETY EVALUATION REPORT SUPPLEMENT
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DIABLO CANYON NUCLEAR POWER PLANT UNIT 2 DOCKET NO.: 50-323 STRUCTURAL AND GE0 TECHNICAL ENGINEERING BRANCH STRUCTURAL ENGINEERING SECTIONS-MASONRY WALLS
- In supplement No.13 to the Diablo Canyon Safety Evaluation Report (which-applies to both Units 1 and 2), the staff recommended the issuance of an operating license subject to the following conditions:
1.
The applicant shall evaluate all the masonry walls in accordance with the requirements of IE Bulletin 80-11 and implement any needed fixes or modifications to meet the bulletin criteria prior to the full power operation. Also, as required by the bulletin, the applicant shall invoke applicable action statement of the plant technical specifications, if the operability of any safety-related system is judged to be in jeopardy, because of safety considerations related to masonry walls.
(As discussed later in this supplement, the applienat has completed the required action and this condition is no longerneeded).
T 2.
The fixes or modifications implemented in (1) above shall not preclude the option of implementing additional modifications if directed by future s^.aff review of the applicant's design criteria.
3.
Prior to start-up following the first refueling, the applicant
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shall resolve the differences between the staff interim criteria kok4Uhh187043y HOLMES86-197 POR
. and the criteria used by the applicant to the satisfaction of the staff and implement the required wall fixes or modifications that
.might res, ult from such a resolution.
By a submittal dated September 26, 1984 responding to IEB 80-11, the applicant provided its evaluation of all masonry walls in Unit 2.
This submittal also indicated required fixes and the applicant's commitment to implement these fixes prior to full power operation. In a letter dated December 26, 1984, the applicant has further informed the staff that required fixes to the masonry walls are now scheduled to be completed prior to Unit 2 fuel load. Thus, the requirements of Item 1 above has been satisfied and it should not be included as a license condition.
The staff met with applicant and its representative to discuss masonry wall issues on October 1-4, 1984 and November 7-9, 1984. The primary purposes of these meetings were:
(1) to review the applicant's masonry wall calculations; (2) to discuss differences between the staff's acceptance criteria and the licensee's criteria; (3) to conduct a site visit to observe masonry wall construction and implemented fixes; and (4) to review the relevant construction documents to ascertain as-built conditions.
As a result of these meetings, the staff finds that the only major difference between the staff's acceptance criteria and the applicant's evaluation criteria is the applicant's use of the energy-balance technique to qualify 42 masonry walls when subject to out-of-plane seismic loading.
. The staff acceptance criteria are based on the working stress approach relying on the elastic range of the wall response. The energy-balance technique results in wall response in the inelastic range.
The staff and its consultant have reviewed the use of this technique in connection with other operating plant responses to IE Bulletin 80-11.
Based on these reviews, a staff position was established concerning the use of the energy-balance technique. This staff position has been implemented on many operating plant reviews. In another meeting with the applicant on November 7-9, 1984, the staff and its consultants discussed the staff position and ensuing applicant options to resolve the issue. The staff concerns with the applicant's use of the energy-balance technique relate to the lack of experimental evidence indicating the applicability of this concept to the masonry construction and also the lack of knowledge to clearly establish the available safety margins. The applicant is currently reviewing the options and will advise the staff of its decision.
Even though the above discussed staf f concerns are yet to be resolved, the staff confirms its earlier recommendation of the issuance of conditional operating license because of the following reasons:
a.
The staff and its consultants reviewed the actual caiculations based upon the energy-balance technique. This review indicated that excursions into the non-linear range of the wall response are limited for Diablo Canyon masonry walls; consequently, resulting maximum displacements are very small (less than 1.0 inch).
i
]
4-b.
The construction of these masonry walls at Diablo Canyon indicate a stable performance under the seismic loading because it includes the following features:
- The walls are fully grouted;
- The walls are reinforced in both horizontal and vertical direction with equal reinforcement ratio; and
- Clip angles are provided at top and bottom boundaries The above findings provide reasonable assurance that the plant can be operated safely while the masonry wall related issues are being resolved in accordance with the following recommended license condition (previous license conditions 2 and 3 are to be deleted).
License Condition Prior to start-up following the first refueling, the applicant shall resolve 4
the differences between the staff criteria and the criteria used by the applicant to the satisfaction of the staff. The licensee shall submit a schedule acceptable to the staff regarding implementation of the required wall fixes or modifications that might result from such a resolution.
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