ML20141D223
| ML20141D223 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck, 05000000 |
| Issue date: | 03/26/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20141D206 | List: |
| References | |
| IEB-80-11, NUDOCS 8604070450 | |
| Download: ML20141D223 (3) | |
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UNITED STATES y
g NUCLEAR REGULATORY COMMISSION r.
j WASHING TON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO MASONRY WALL DESIGN, IE BULLETIN 80-11 HADDAM NECK PLANT DOCKET NO. 50-213
1.0 BACKGROUND
IE Bulletin 80-11 required licensees to identify plant masonry walls and their intended functions. Licensees were also required to present reevaluation criteria for the masonry walls with the analyses to justify those criteria.
If modifications were proposed, licensees were to state the methods and schedules for the modifications.
r In response to IE Bulletin 80-11, Connecticut Yankee Atomic Power Company (CYAPCO) provided NRC with letters plus attachments, dated November 4, 1980, March 3,1981 and June 26, 1981, describing the status of masonry walls at the Haddam Neck plant. These documents were reviewed, and a request for additional information was sent to the licensee on September 28, 1982, to which the licensee has responded by letter dated December 3, 1982. The review of this response revealed several unresolved issues, so another request for additional information was sent on July 22, 1985. During a site visit on October 28-30, 1985, the NRC, its consultants, and the licensee discussed responses to the latest requests for information and reviewed plant modifications made in response to IE Bulletin 80-11. The licensee subsequently submitted the written respenses by letter dated December 31, 1985.
B604070450 760326 2.0 EVALUATION
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U The findings reported in this Safety Evaluation Report (SER) are based on the attached Technical Evaluation Report (TER), Attachment 1, prepared by Franklin Research Center (FRC) as a contractor to NRC. This TEP contains the details of construction techniques used, technical informatfor, reviewed, acceptance criteria, and technical findings with respect to masonry wall i
construction at Haddam Neck Plant. The staff has reviewed this TER and concurs with its technical findings. The following is our summary of the major technical findings:
1.
The licensee has evaluated the Haddam Neck masonry walls using the working stress criteria consistent with the staff acceptance criteria (Appendix A of the TER).
Initially, the licensee's reevaluation criteria permitted higher allowable stresses in masonry compared to the allowable stresses specified in the staff acceptar.ce criteria.
However, upon further examination and refined analyses of the walls, the licensee demonstrated that the Haddam Neck Walls can be qualified using the staff allowable stresses. Therefore, it is concluded that the reevaluation of the Haddam Neck. masonry walls complies with the intent of the staff acceptance criterf a.
2.
The licensee has also demonstrated that the Haddam Neck masonry walls can withstand the seismic loading resulting frem the review under Systematic Evaluation Program (SEP).
3.
The licensee has modified the masonry walls using iihe following appr: aches.
Modification of the top and sides of the wall from the adjacent boundary supports to avoid imposition of stresses on the masonry walls due to large interstory displacements; Insertion of angles at the wall edges to assure pinned boundary conditions; Insertion of steel members across a wall face to transfer wall loads to the boundaries and limit wall span; Insertion of steel bumpers at the top of the wall to prevent overturning and at the base of the wall to prevent slidings; Shielding so that falling blocks would not hit safety-related equipment; L
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3 Removal of the wall; Rerouting of pipes; and Relocation of pipe supports.
The licensee's modification approaches are found to be adequate as the modified walls comply with the staff acceptance criteria.
4.
During a site visit on October 29, 1985, the staff had noted some diagonal cracks in walls CYTB1009 and CYTB1010. The staff requested the licensee to submit its plan for corrective actions to address these cracks. By a letter dated February 18, 1986, the licensee indicated that its reanalysis of these two walls, which accounted for the existing cracks, did not alter the conclusions drawn from the previous analysis. However, not withstanding the results of this reanalysis, the licensee has conunitted to repair these cracks such that the repaired joints will have the original design strength in both bending and shear resistance. By letter dated March 7, 1986, the Ifcensee has indicated that the repairs will be completed during the next operating cycle of the unit and crack locations will be monitored for any indication of reappearance.
The licensee's planned corrective ac' ions adequately addresses the concerns associated with the cracks in walls CYTB1009 and CYTB 1010.
3.0 CONCLUSION
3ased on the above findings, the staff concludes that Items 2(b) and 3 of the IE Bulletin 80-11 have been fully implemented at Haddam Neck Plant and that there is a reasonable assurance that the safety-related masonry walls at Haddam Neck Plant will withstand the specified design load conditions without impairment of (a) wall integrity or (b) the performance of the required safety functions.
Principal Contributor:
N. Chokshi, RRAB, DSR0