ML20137R164

Forwards RAI Re 960819 Response to NRC Bulletin 96-004, Chemical,Galvanic,Or Other Reactions in Spent Fuel Storage & Transportation Casks

ML20137R164
Person / Time
Site:	Oconee
Issue date:	04/08/1997
From:	Kobetz T NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Hampton J DUKE POWER CO.
References
IEB-96-004, IEB-96-4, NUDOCS 9704140054
Download: ML20137R164 (6)

Text

r-UNITED STATES q g

) ,, j - NUCLEAR REGULATORY COMMISSION

& WASHINGTON. D.C. - *1

\.' ***** April 8, 1997 Mr. J. W. Hampton-

• Vice President y Duke Power Company '

Oconee Nuclear Plant P.O. Box 1439 Seneca. SC 27679

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION - NRC BULLETIN NO. 96-04.

" CHEMICAL. GALVANIC. OR OTHER REACTIONS IN SPENT FUEL STORAGE AND

. TRANSPORTATION CASKS"

Dear Mr. Hampton:

This refers to your response dated August 19. 1996, to Nuclear Regulatory

' Commission Bulletin No. 96-04. " Chemical. Galvanic, or Other Reactions in Spent Fuel Storage and Trans)ortation Casks." Your submittal incorporated information prepared by VECTM Technologies. Inc. (VECTRA) in response to the bulletin. By letter dated March 24, 1997. NRC notified VECTRA that their response to the bulletin lacked sufficient information for NRC to confirm

. VECTRA's conclusion that hydrogen generated during loading and unloadino activities would not exceed the lower flammable limit. Therefore, we also believe that your submittal lacks the same information.

A notable concern is that VECTRA's August 16, 1996. submittal utilized a

" transfer resistance factor." to adjust test data to account for: (1) the hydrogen retained in the dry shielded canister water column due to diffusion transport resistance, and (2) hydrogen lost through the open vent. This conversion factor was develo)ed based on single samples taken during the loading of two different cascs. The staff does not believe sufficient information was obtained to accurately determine a conversion factor of this type. This is of concern because your staff used VECTRA's unclear and '

incomplete information as the basis for implementing procedural enhancements to minimize potentially hazardous conditions during cask loading and unloading.

Additionally, your August 19, 1996, submittal lacked sufficient detail for the staff to determine if hydrogen concentrations could accurately be detected and whether adequate actions would be taken to minimize hazardous conditions.

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. ._,4 . .4m4 r Mr..J. W. Hampton ,

Specifically, your submittal did not address monitoring hydrogen .

- concentrations during welding and cutting evolutions nor provide the specific hydrogen concentration at which corrective actions,-if necessary, would be implemented.

The staff acknowledges that ~aparoximately 60 NUHOMS canisters, at four '

different reactor sites, have 3een. loaded and welded without any type of ignition indications or incidents. Thus,~the staff does not have a safety issue. at this time, regarding the use of.the NUHOMS system. However, the technical analyses and engineering work submitted in response to NRC Bulletin -

No. 96-04 lacked a sufficient technical basis to support your conclusion that the hydrogen generated would not exceed the lower flammable limit.  !

Enclosed is a request for additional information related to your submittal.  ;

-If you have questions regarding this matter, please contact me at '

(301) 415-8538.

Sincerely.

Original signed by /s/

Timothy J. Kobetz. Project Manager Spent Fuel Licensing Section Spent Fuel Project Office Office of Nuclear Material Safety l and Safeguards 1

Dockets 72-4. 50-269/270/287 i i

Enclosure:

Request for Additional Information i

cc: NUHOM's Owners Group l Nuclear Energy Institute )

Service List l Distribution:.

' Docket 72-4 . ' ' ~w/ - .. NRC encl.File-Center PUBLIC NMSS r/f SFP0 r/f rDockets 50-269/270/287 S$hankman CHaughney WKane Region II DLaBarge NRR JDavis. NRR KBattige- VTharpe(2) MBailey BReckley, NRR WGloersen, RII  !

• See attached concurrences

.Q OFC SFP0 W E NRR

• E /P0

• E SFP0 /E l NAME TKobetz:dd:vt ESullivan FSturz Eleeds N DATE- f /f /97 L/ / / /97 t/ / / /97 M/7/97 \

C - COVER E = COVER & ENCLOSURE N = NO COP ( }

OFFICIAL RECORD COPY G:\nuhams24\7210049 1.oco I ,

( i 4/8/97 :dd:

110055

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. Oconee Nuclear Station Units 1, 2,.and 3 cc: ,

. Mr. Paul R. Newton Mr. J. E. Burchfield, Jr.

i legal Department (PB05E) Compliance Manager Duke Power Company Duke Power Company-422 South Church Street Oconee Nuclear Site Charlotte, North Carolina 28242-0001 P. O. Box 1439  ;

Seneca, South Carolina 29679 J. Michael-McGarry, III Esquire

.Winston and Strawn Ms. Karen E. Long .

.1400 L Street. NW. Assistant Attorney General-Washington, DC 20005 North Carolina Department of l' Justice Mr. Robert B. Borsum P. O. Box 629  ;

Framatome Technologies Raleigh, North Carolina 27602  :

Suite 525

1700 Rockville Pike Mr. G. A. Copp i Rockville. Maryland 20852-1631 Licensing - EC050 ,

Duke Power Company  :

Manager, LIS 526 South Church Street l NUS Corporation Charlotte, North Carolina 28242-0001 i 2650 McCormick Drive, 3rd Floor  :

Clearwater. Florida 34619-1035 Senior Resident Inspector U. S. Nuclear Regulatory Commission '

Route 2. Box 610 Seneca. South Carolina 29678 Regional Administrator, Region II i U. S. Nuclear Regulatory Commission 101 Marietta Street NW. Suite 2900 ,

Atlanta, Georgia 30323 j Max Batavia, Chief Bureau of Radiological Health

-South Carolina Department of Health and Environmental Control  ;

e 2600 Bull Street -

Columbia, South Carolina 29201  ;

County Supervisor of Oconee County -

Walhalla. South Carolina 29621 ,

Mr. Dayne H. Brown, Director .

' Division of Radiation Protection North Carolina Department of Environment, Health and Natural Resources P. O. Box 27687 Raleigh,' North. Carolina 27611'-7687 ,

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3

. Nuhoms Daners' Group.(72-1004) i (Mr. John P Stetz Mr J. W. Hampton Vice President - Nuclear. V,cd President .

Davis Besse- Duke Power Company  !

Centierior Service Company Oconee Nuclear Site

.c/o Toledo Edison Company P. O. Box 1439 1 5501 North State Route 2 . Seneca. SC 29679 Oak Harbor. OH 43449 i Hr. Janes R. Shetler

' !v GPU Nuclear Corporation Deputy Assistant General Manager l

. Mr Michael B. Roche - Nuclear  !

Vice President and Director Sacramento Municipal Utility. l Oyster Creek. Nuclear Station District  !

~P. O. Box.388 6201 S Street Route 9 South - P. O. Box 15830 .

Forked River,it) 08731-0388 Sacramento CA 95813 '

i Mr. Robert G. Byram Mr.'Jan Hagers  :

Senior Vice President - Nuclear DEPARTMENT OF ENERGY ,

Pennsylvania Power and Light TMI/FSV Licensing Project Manager i Company .

Idaho Operations Office .

2 North Ninth Street 785 Doe Place Allentown PA 19101 Idaho Falls. ID 83403 .

Mr. William S. Crser Executive Vice President

' Nuclear Generation [ Brunswick]  ;

Carolina Power and Light Company '

Sbuhp t, NC 28461 Mr. Charles H. Cruse Vice President - Nucl. ear Energy Calvert Cliffs Nuclear Plant 1650 Calvert Cliffs Parkway ,

Lusby MD P0657-4702 i

Mr. William B. Orser' '

. Executive Vice President Nuclear Generation H..B. Robinson 2 P. O. Box 1551-

' Rale 19h, NC. 27602 >

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e REQUEST FOR ADDITIONAL INFORMATION (RAI) ON THE OCONEE NUCLEAR PLANT RL5PONSE TO NUCLEAR REGULATORY BULLETIN N0. 96 04 ,

IL. Provide justification that sufficient data was obtained from field experience and testing to support the methodology and calculations used in the computer simulation. Trio justification should support your conclusions.for pressurized water reactor (PWR) fuel storage. In addition.. provide the methodology and calculations used in the computer

• simulation.

lhis request is based on, but not limited to, the following information:

• VECTRA used data from only four canisters (0conee dry shielded canisters (DSCs) Nos. 37 through 40), loaded with PWR fuel, to justify that hydrogen concentrations will not reach the  ;

' flammability limit. In addition, the hydrogen samples were not ,

taken by continuously monitoring the levels during the loading of l DSCs 37 through 40. Therefore, they may not be representative cf  ;

the highest hydrogen concentrations obtained during cask loading. ,

. In the VECTRA August 16. 1996, submittal, a " transfer resistanca factor" was used to calculate the amount of hydrogen generated in the DSC air space. However, this conversion factor was developed based on single s:mples taken during the loading of two different 1

-casks. The staff does not believe sufficieni. information was l obtained to accurately determine a conversion factor of this type.  !

Furthermore, when the transfer resistance factor is not used to adjust test data, the hydrogen levels )roduced exceed the lower flammability limit. It appears that t1e conversion factor was also used by the com) uter simulation discussed in VECTRA's October 18. 1996, su)mittel.

• The test methods and computer modeling used to obtain and evaluate data are vague and not presented in a manner that supports the final conclusions.

. Some tests are terminated at approximately 165 F even though  !

the hydrogen production rate appears to still be increasing. )

The computer simulations were performed at temperatures i below 160*F. Therefore, the tests and computer simulations may not bound all conditions.

. There is no discussion of the maximum achievable hydrogen contentrations derived from the tests or computer simulations. All that is stated is that "H . concentrations 2

remain below the 4% flammability limit for water temperatures Delow 160'F."

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. 12. - Provide justification that a ' sufficient safety margin exists between the amount of hydrogen generated prior to welding and the lower flammability- ,

limit. ,

Data taken during the loading of the.four Oconee casks indicated that.  :

in a flame sprayed aluminum and boric acid environment, hydrogen levels l could be generated in excess of 50% of the lower flammable limit. l However, there is no discussion of the recommended margin of safety that should exist between the amount of hydrogen produced and-the lower .

flammability limit. The staff has previously accepted a 0.4% limit of I hydrogen generation, which is 10% of the lower flammability limit. i

) 3. Describe the methods used to' monitor and control hydrogen during  !

welding, grinding, or cutting operations associated with loading or ,

' unloading activities.  ;

4 Provide the specific hydrogen concentration at which time the procedural ]

steps would implement corrective actions to minimize hazardous conditions.  !

As stated in RAI Question No. 2. VECTRA's responses to NRC Bulletin No.

96-04 did not contain a discussion of the recommended margin of safety that.should exist between the amount of hydrogen produced and the flammability limit. The staff has previously accepted a 0.4% limit of hydrogen generation, which is 10% of the lower flammability limit.

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