ML20217A666

Requests Addl Info Concerning Boraflex Degradation in Millstone 2 Spent Fuel Pool Storage Racks to Support Review of Util 901001 Submittal.Info Re Gamma Doses to Boraflex Matl During Blackness Testing & Storage Patterns Requested

ML20217A666
Person / Time
Site:	Millstone
Issue date:	11/15/1990
From:	Vissing G Office of Nuclear Reactor Regulation
To:	Mroczka E CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO.
References
TAC-77726, NUDOCS 9011210213
Download: ML20217A666 (3)

Text

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UNITED STATES kC J.o j_ -- F g NUCLEAR REGULATORY COMMISSION 1

,E j ' WASHINGTON, D. C. 20556 k...../ November 15, 1990 '

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, ' Docket No. 50-336 Mr. Edward J. Mroczka l Senior:Vice President l Nuclear Engineering and Operations  :

Connecticut Yankee Atomic Power Company u . Northeast Nuclear Energy Company ll P. O. Boxt270 3' Hartford, Connecticut 06141-0270 J

Dear Mr. Mroczka:

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SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION CONCERNING BORAFLEX DEGRADATION o

IN MILLSTONE-2 SPENT FUEL POOL STORAGE RACKS (TAC NO. 77726)

.We are reviewing your information submitted on the subject issued by-letter i dated October 1, 1990. In order to complete our review, we need information ,

concerning the propagation of. the gaps in degraded assendlies and the i

!. Jeriticality analysis-ofLdegraded boraflex assemblies. Specifically, we request  !

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answers to the.following concerns:-

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' l ~. Preliminary results from the blackness tests indicate that 45 panels had a

.. gap in-the boraflex meterial with the. largest single _ measured gap approximately 1.8 inches wide. What was the total accumulated gamma-

• ' radiation to tnese panelstat the' time of the blackness tests? What additional ganna dose will be accu & 'ated by the boraflex panels before-  ;

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.theLnext. blackness: testing'and what additional shrinkage (gap size) could '

this:. cause?

.2. JIt- is' reported: that the.results of the CE criticality analysis confirms that the K-eff of-the. spent fuel pool is.less than 0.95 for 2.7-inch gaps

' ' located at-the same axial. elevation.throughout Region l'for the fuel-j Eassemblies enriched.to 4.5 weight percent U-235. Since the present fuel-

. assemblies stored-in Region 1 are arranged in a two-out-of-four storage ,

, Lpattern (checkerboard), was- this the configuration assumed in the CE- '

7 m criticality analysis?j How much margin existed between the calculated

- K-eff and 0.957 = As a result of previous Question 1~ above, could gaps

larger than the 2.7 inches assumed in the criticality analysis occur with

further_ irradiation?-

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9011210213 901115 i L PDR ADOCK 05000336' -

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Mr. Edward J. Mroczka Millstone Nuclear Power Station Northeast Nuclear Energy Company Unit No. 2 cc:

Gerald Garfield, Esquire R. M. Kacich, Manager Day, Berry and Howard Generation Facilities Licensing

!; . Counselors at Law Northeast Utilities Service Company

. City Place Post Office Box 270 Hartford, Connecticut 06103-3499 Hartford, Connecticut 06141-0270 i'

W. D. Romberg, Vice President D. O. Nordquist 4 Nuclear Operations Director of Quality Services Northeast Utilities Service Company Northeast Utilities Service Company Post Office Box 270 hi,i, 6ff ice Box 270 Hartford, Connecticut 06141-0270 Hartford, Connecticut 06141-0270 Kevin McCarthy, Director Regional-Administrator

' Radiation Control Unit- . Region I L Department of Environmental Protection U. S. Nuclear Regulatory Commission K State Office Building 475 Allendale Road h Hartford,~ Connecticut 06106 King of Prussia, Pennsylvania 19406 Bradford S. Chase, Under Secretary First Selectmen Energy Division .

Town of Waterford Office of Policy and Management Hall of Records 80 Washington Street 200 Boston Post Road Hartford, Connecticut .06106 Waterford, Ccnnecticut 06385 h- S. E.'Scace, Nuclear Station Director W. J. Raymond, Resident Inspector -

-Millstone Nuclear Power Station Millstone Nuclear Power Station Northeast Nuclear Energy Company c/o U. S.. Nuclear Regulatory Commission i Post Office Box 128 Post Office Box 811

[ Waterford, Connecticut 06385 Niantic,-Connecticut 06357 J. S. Keenan, Nucie n Unit Director Charles Brinkman, Manager Millstone Unit N:,. 2 Washing ~ ton' Nuclear Operations Northeasi. Nuclear Energy Company C-E Power Systems

' Post Office Box 128 Combustion Engineering, Inc.

Waterford. Connecticut 06385' 12300 Twinbrook Pkwy E

Suite 330 Rockville, Maryland 20852 ,

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• ?.. b November 15, 1990  ;

Mr. Edward J. firoczka We request your response within 45 days from receipt of this letter.

The requirements contained in this letter affect fewer than ten respondents, f and, therefore, is not subject to Office of lianagement and Budget review under '

P.L.96-511.

Sincerely, i S

Guy S. Vissing, Senior Project Manager Project Directorate 1-4 Division of Reactor Projects 1/11 Office of. Nuclear Reactor Regulation

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