ML20199J084

Submits Request for Technical Assistance to Determine Technical Adequacy of Util Revised Design Calculations for Reactor & Turbine Bldgs Blowout Panels

ML20199J084
Person / Time
Site:	Nine Mile Point
Issue date:	03/13/1996
From:	Cooper R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:	Varga S NRC (Affiliation Not Assigned)
Shared Package
ML20199J065	List: ML20199J059 ML20199J084 ML20199J091 ML20199J097 ML20199J104
References
FOIA-97-375 NUDOCS 9711280049
Download: ML20199J084 (2)

Text

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UNITED STATES C a  !

NUCLEAR REGUI). TORY COMMISSION  !

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March-13, 1996 I I

MEMORANDUM T0: Steven A. Varga, Director Division of Reactor Projects-I/II 1 Office of-Nuclear Reactor Regulation FROM: Richard W. Cooper, II, Director (

ft$1 vision of Reactor Projects, Reg' on I

SUBJECT:

REQUEST FOR TECHNICAL ASSISTANCE ON NINE MILE POINT 1 REACTOR AND TURBINE BUILDING BLOWOUT PANELS Your assistance is requested to detsrmine the technical adequacy of Niagara-Mohaw Power Corporation's (NMPC) revised design calculations for the reactor and turbine building blowout panels. These calculations are related to an event (LER 50-220/95-05) that identified the existence of an initial construction deficiency and a subsequent 1993 error in design assumptions.

The construction deficiency involved the use of oversized fasteners, and the design control deficiency resulted in the fasteners remaining in place for an additional 17-months. These errors resulted in the failure of NMPC to identify that the reactor and turoine buildinc blowout panels wculd not have relieved the internal pressure of the buildings following certain accident conditions (91. psf and 89 psf, respectively) at the design value of 45 psf.

The UFSAR states that pressure relief of the structures through the blowout panels will prevent excessive internal pressure on the superstructure walls, roof and their supports, which would fail at an internal pressure in excess of 80 psf.

At the Enforcement Panel held on March 5,1996 to discuss this event, the Region was questioned as to the status of NRC review of the revised calculations that were performed by NMPr that resulted in removal of approximately one-half the fasteners holding the panels in place. It was determined at the Panel meeting that the NRC's independent confirmation of the adequacy of the subject calculations would be appropriate. While the Region had the calculations, it was subsequently learned that the Region lacked the expertise to review calculations for a structural problem of this type.

Accordingly, we request your assistance in prriiding the adequacy review of the. revised calculations.

This TIA proposal has been discussed with Darl Hood of your staff. The Region I paint of contact is Richard Conte in the Division of-Reactor Projects (610) 337-5183. The calculations wero transmitted to NRR on March 12 under separate cover. We would appreciate a preliminary review by April 12,-1996 so that the adequacy of this element of NMPC's corrective actions can be properly assessed at the Enforcement Conference planned for the subject event and scheduled for April 15, 1996. A response is requested by May, 15, 1996.

9711290049 971121 PDR O

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Steven A. Varga- 2 CC:

'R. Conte, RI/0RP-

M. Modes, RI/DRS

.H. Eichenholz, Rl/DRP

8. Norris, RI/DRP L. Marsh, NRR/PD I-l D. Hood, NRR/PD I-1 M.'Oprendek, RI/DRPI R. Gallo, RI/DRP  ;

J. Wiggins,-RI/DRS R. Blough,~ RI/DRS E. Merchoff, RII W.-Axelson, RIII J. ' Dyer, .RIV .

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