ML20138J222

Forwards Consequence Analysis for Failure of Fuel Bldg South Wall Into Spent Fuel Pool,Per IE Bulletin 80-11.Actions Summarized in Analyses Provide Satisfactory Permanent Solution to Bulletin Concerns

ML20138J222
Person / Time
Site:	Maine Yankee
Issue date:	12/11/1985
From:	Whittier G Maine Yankee
To:	Thadani A Office of Nuclear Reactor Regulation
References
6804L-FWS, GDW-85-308, IEB-80-11, MN-85-206, NUDOCS 8512170462
Download: ML20138J222 (4)

Text

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~ EDISON DRIVE MAME HARHEE ATOMICPOWER00MPARUe nuouSra. ux,ne o<sa6 g (207) 623-3521 e

December 11, 1985 MN-85-206 GDW-85-308 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Mr. Ashok Thadani, Director PWR Project Directorate #8 Division of Licensing

References:

(a) License No. OPR-36 (Docket No. 50-309)

(b) NRC IE Bulletin No. 80-11-- Masonry Wall Design (c) MYAPCo Letter to USNRC dated January 25, 1985, Maine Yankee Masonry Wall Design - IE Bulletin 85-11 (MN-85-15)

(d) NRC Letter to MYAPCO, dated November 8, 1985 (NMY 85-180)

Subject:

Resolution of Concerns Regarding Spent Fuel Pool Wall Gentlemen:

NRC acceptance of Maine Yankee's IE Bulletin 80-11 review and upgrades was

~

provided by Reference (d) with the exception of the request for a consequence analysis for failure of the Fuel Building south wall into the Spent Fuel Pool (SFP).

We have assessed the effect of blocks from the wall falling into the SFP, on both the capability of cooling the fuel, and on the structural integrity of the spent fuel racks. Summaries of our analyses are attached for your review. We have concluded that the stainless steel racks would not be-significantly damaged by the debris,- and that spent fuel which may be stored in this section of the pool would be adequately cooled whether stored in standard or compacted arrays.

In order to protect recently discharged fuel Maine Yankee proposed in Reference (c) to:

Limit placement of irradiated fuel which has decayed less than 180 days to the north end of the SFP, and Maintain the SFP manipulator bridge parked over the north end of the pool whenever irradiated fuel which has decayed less than 180 days is stored in d.

the pool, except when the bridge is manned and in use.

8512170462 851211 gDR ADOCK 05000309 PDR 6804L-FWS @

MAINE YANKEE ATOMIC POWER COMPANY

United' States Nuclear Regulatory Commission Page'Two

! Attention: Mr. Ashok Thadani, Director MN-85-308

- Based upon the analyses summarized in the enclosures, these actions provide. a satisfactory permanent' solution to the concerns identified in

. Re ference. (b) . -

Please, feel free to contiact us if you have any questions.

Very truly yours,

' MAIE YA*EE ATOMIC ~ POWER COWANY kbW G. D. Whittier, Manager Nuclear Engineering & Licensing GDW/bjp

Attachment:

-(2 Pages) cc:: Dr. Thomas E. Murley Mr. Cornelius F. Holden 6804L-FWS

M AINE Y ANKEE' ATOMIC POWER COMPANY ATTACHNENT A ABILITY TO COOL SPENT FUEL Analysis of_ the impact on the ability to cool the spent fuel, considering debris from a masonry block wall falling into the spent fuel pool and blocking the exit funnels of.several spent fuel storage cavities, indicates that the stored fuel will' be adequately cooled if sufficient decay time has elapsed.

The limiting factor in this circumstance is the reduction in exit flow area.

Yankee Atomic Electric Company assessed the ability to cool spent fuel stored in fuel storage rack cavities whose exit funnels have been blocked by debris from a fallen masonry block wall. Complete blockage of the top exit of the storage cavity was assumed with only the four 1/2-inch diameter holes in the upper funnel area providing exit flow area. Two cases were analyzed:

1. The case where pool cooling has been lost and bulk pool liquid has been heated to saturation and boiled off to just.above the top of the spent!

fuel racks.

2. The case where pool cooling continues, which is assumed to maintain the pool bulk liquid temperature 100oF subcooled at the inlet of the fuel storage racks.

The results of these analyses indicate that cooling of spent fuel stored in cavities with exit funnels blocked by debris from U1e fallen wall will be adequate if the spent fuel has undergone sufficient decay. Analysis results

. indicate normal fuel assemblies and/or. consolidated pin bundles will be adequately cooled if the fuel has decayed for a minimum of 180 days.

6804L-FWS

MAINE YANKEE ATOMIC POWER COMPANY ATTACH ENT B STRUCTURAL INTEGRITY OF SPENT FUEL RACKS FOLLOWING A BLOCK WALL COLLAPSE Yankee Atomic Electric Company has analyzed the effects of a postulated collapse of- the Fuel Building south masonry wall onto the fuel racks located

-in the spent fuel pool.

The results of this analysis indicate that the structural integrity of the spent' fuel racks will not be adversely affected.

-The . analysis calculated an upper limit of energy absorbed by the spent fuel racks due' to the impact of the failed block wall. This energy was compared to the energy.of a fuel bundle drop analyzed by GCA Corporation, par Systems, (par) when they structurally qualified the racks. The comparison showed the

-par analysis bounded this new calculation. Thus, the racks are considered

. structurally acceptable for the subject loading.

6804L-FWS