ML17054B391
| ML17054B391 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 02/04/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17054B390 | List: |
| References | |
| TAC-69217, NUDOCS 8502130575 | |
| Download: ML17054B391 (2) | |
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'+n 0~*~0 UNITE0 STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION NINE MILE POINT NUCLEAR STATION, UNIT I DOCKET NO. 50-220 Cracking was identified in a portion of the reactor building wall coupled to the screenhouse structure.
The cracking was believed to be caused by differential thermal expansion between the two buildings.
In the staff's Safety Evaluation of December 29, 1983, the staff endorsed the licensee's proposed long-term action of decoupling the screenhouse wall from the reactor building wall by cutting an expansion joint in the screenhouse wall as a long term solution to the reactor building wall cracking.
The staff has been informed by the licensee that the decoupling was achieved on May 17, 1984, by cutting a tapered section in the screenhouse wall portion which was butting against the reactor building wall and by drilling a series of holes in the taper, thus creating a weak section and resulting in the crushing of the concrete in the tapered section.
The tapered section was chipped to the desired shape and a compressible material was installed in the slot between the wedge tip of the modified screenhouse wall and the reactor wall to prevent the infiltration of soil from outside the screenhouse.
After the decoupling of the two walls, the cracks in the reactor building wall became less visible.
From the continuous monitoring of the wall behavior, it appears that after decoupling the originally restrained portions of the reactor building wall are slowly returning to the unrestrained shape indicating that the reactor building wall has been subjected to elastic deformation due to the restraint.
On the basis of the review of the information submitted by the licensee, the staff has concluded that the concern regarding the reactor building/
screenhouse wall cracking has been satisfactorily resolved.
Principal Contributor:
C.
P.
Ton Dated:
February 4, 1985 8502130575 850204 PDR ADOCK 05000220 8
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