ML20137R372

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

ML20137R372
Person / Time
Site:	Calvert Cliffs
Issue date:	04/08/1997
From:	Kobetz T NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Cruse C BALTIMORE GAS & ELECTRIC CO.
References
IEB-96-004, IEB-96-4, NUDOCS 9704140102
Download: ML20137R372 (6)

Text

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7 NUCLEAR. REGULATORY COMMISSION c, ,!. WASHINGTON, D.C. 30660 4001 e % ***** ~

April 8, 1997 Mr. Charles H. Cruse t Vice President o Nuclear Energy Baltimore Gas and Electric Company.

Calvc-t Cliffs Nuclear Plant

- 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION'- NRC BULLETIN 96-04.

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

Dear Mr.' Cruse:

1 This refers to your responses dated August 19 and November 4, 1996, to Nuclear Regulatory Commission Bulletin 96-04, " Chemical, Galvanic, or Other Reactions in Spent Fuel Storage and Transportatior Casks." ' Your stCmittals incorporated information prepared by VECTRA Technologies. Inc. (VECTRA) in response to the '

bulletin. By letter dated March 24,1997.. NRC notified VECTRA that its response to the 'oulletin lacked sufficient information for NRC to confinn VECTRA's conclusion that hydrogen generated during loading and unlwding activities would not exceed the lower flamable limit. Therefore, wa also believe thet your submittals lack 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 I 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 cas:s. The staff does not believe mfficient information was obtained to accurately determine a convers' . actor of this

. type. This is of concern because your-staff used VECTRA's unclear and ;p incomplete information as the bas 1s for implementing procedural enhancements

-to minimize potentially hazardous conditions during cask loading and unloading.

Additionally, your August 19,19s6 submittal lacked suffic'ient detail for the l staff to determine if hydrogen concentrations could accurately be detected.

' Your submittal also did not provide enough information to support using 50 percent of the lower hydrogen flammability limit as the point at which you would implement actions to reduce the hydrogen concentration.  ;

i The staff acknowledges that aparoximately 60 NUHOMS canisters, at four different reactor sites, have aeen loaded and weldad 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 96-04 lacked a sufficient technical basis to support your conclusion that the

.. hydrogen generated would not exceed the lower flammabic limit.

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LEnclosed is a rcquest for additional information related to 'your submittils.

ilf you have questions regarding thisl matter.~please contact me at J.301) 415-8538.

Sincerely.

Original signed by '/s/

i Timothy J. Kobetz, Project. Manager

, Spent Fuel Licensing Section Spent Fuel Project Office Office of Nuclear Material Safety and Safeguards i

l )Dickets 72-8. 50-317, 50-318 L Ericlosure: As stated i

cc: NUH0M's Owners Group n Nuclear Energy Institute

: Service List I

)istribution: w/ encl. . . . _

Docketss 72-8 L50-317/318 - :PUBLICL.. NMSS r/f SFP0 r/f

, vNRC File: Center- WKane CHaughney SShankman MBailey KBattige . VTharpe(2) Pegion I ADromerick NRR JDavis. NRR

-BReckley. NRR CAnderson. RI *see previous concurrence OFC ' SFPO* i E NRR* E SFPO* E SFP0 j E NME' TKobetz:da:vt ESulliyan FSturz Eteeds k DATF 03/28/97' N E 04/01/97 04/03/97 f/397 C = COVER E = COVER h ENGLOSURE 4 = NO COPY OFFICIAL RECORD COPY G:\nuhoms24\7210C4gl.cc 4/8/97 :dd I i

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. .Nuhoms Owners Group (72-1004)

Mr.~ John P. Stetz Mr. -J. W - Hampton Vice President - Nuclear. Vice President. '

. Davis'Besse .

Duke Power Company.

Centierior Service Company Oconee Nuclear Site c/o Toledo Edison Company P. O. Box 1439 5501 North Stdte Route 2 Seneca, SC 29679 ,

Oak Harbor, OH 43449; Mr. James R. Shetler '

GPU Nuclear Corporation: Deputy Assistant General Manager Mr Michael B. Roche - Nuclear i Vice President and Director Sacramento Municipal. Utility '

Dyster Creek Nuclear Station District-P. O. Box 388- 6201 S Street  :

' Route 9 South P. O. Box 15830  :

Forked River, NJ 08731-0388 Sacramento, CA 95813 i Mr. Robert G. Byram Mr. Jan Hagers' Senior Vice President.- Nuclear DEPARTMENT OF ENERGY Pennsylvania Power and Light- THI/FSV Licensing Project Manager '

Company- Idaho Operations Office.

2 North Ninth Street 785 Doe Place

- Allentown. PA~ 19101 Idaho Falls, ID '83403 Mr. William S. Orser Executive Vice President

. Nuclear Generation [ Brunswick)

- Carolina Power and Light Company P. O. Box 10429 ,

Southport, NC 28461  ;

Mr. Charles H. Cruse Vice President - Nuclear Energy-Calvert Cliffs Nuclear Plant 1650 Calvert Cliffs Parkway Lusby. MD- 20657-4702 4

'Mr. William B. Orser Executive Vice President .

' Nuclear Generation i

. H. B. Robinson 2.  ;

P. O. Box 1551 Raleigh NC . 27602  ;

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Calvert Cliffs Nuclear Power Plant '!

-,. 5 Mr. Charles H. Cruse Calvert. Cliffs Nuclear Power Plant- Unit Nos. 1 and 2 CC: 1 President .

Mr. Joseph H. Walter, Chief Engineer 1

-Calvert County Board of Public Service Commission of 1 Commissioners Maryland 175 Main Street Engineering Division l Prince Frederick, MD 20678 6 St. Paul Centre <

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Baltincre, MD 21202-6806 0.- A. Brune, Esquire General' Counsel Kristen A. Burger, Esquire  ;

Baltimore Gas and Electric Company Maryland People's Counsel i P.O. Box 1475 6 St. Paul Centre  ;

Baltimore, MD 21203 Suite 2102 Baltimore, MD 21202-1631 l Jay E. Silberg Esquire  ;

Shaw. Pittman, Potts and Trowbridge Patricia T. Birnie. Esquire i

.2300 N Street. NW Co-Director Washington, DC 20037 Maryland Safe Energy Coalition 1

'P.O. Box 33111 Mr. Terrence J. Camilleri. Director. Baltimore. ' MD 21218 NRM

'Calvert Cliffs Nuclear Power Plant Mr. Larry Bell i 1650 Calvert Cliffs Parkway NRC Technical Training Center l Lusby, MD 20657-47027 5700 Brainerd Road Chattanooga. TN 37411-4017 Resident Inspector c/o U.S. Nuclear Regulatory Commission P.O. Box 287 St. Leonard, MD 20685 M Richard I. McLean Administrator - Radioecology Department of Natural Resources 580 Taylor Avenue Tawes State Office Building B3.

Annapolis, MD 21401 Regional Administrator, Region I U.S. Nuclear Regulatory Commission' 475 Allendale Road

King of Prussia.'PA 19406

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- i .- REQUEST FOR ADDITIONAL INFORMATION (RAI) ON THE CALVERT CLIFFS NUCLEAR PLANT RESPONSE TO NUCLEAR REGULATORY BULLETIN 96 04

1. Provide justification that sufficient data was obtained from field experience and testing to sup> ort the methodology and calculations used in the compter simulation. T1e justification should support your conclusions for pressurized water reactor (PWR) fuel storage. In addition, provide the methodology and calculations used in the' computer simulation.

This 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 DSCs 37 through 40. Therefore. they may not be representative of -

the highest hydrogen concentrations obtained during cask loading.

. In the VECTRA August 16, 1996, submittal, a " transfer resistance factor" was usrJ to calculate the amount of hydrogen generated in the D5C air space. However, this conversion factor was developed )

based on single samples taken during the loading of two different casks. The' staff does not believe sufficient information was 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 l flammability limit. It appears that tie conversion factor was I also used by the com] uter simulation discussed in VECTRA's I October 18, 1996, su]mittal.

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

final conclusions. 1

• Some tests are terminated at approximately 165'F even though ,

the hydrogen production rate appears to still be increasing. l The computer simulations were performed at temperatures l below 160 F. Therefore, the tests and computer simulations l may not bound all conditions.

• There is no discussion of the maximum achievable hydrogen concentrations derived from the tests or computer i'

simulations. All that is stated is that "H concentrations 2

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

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). 2. Provide justification that a sufficient safety margin exists between the q

. amount of hydrogen generated prior to welding and the lower flammability i limit. j 1

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

4 in a flame sprayed aluminum and' boric acid environment, hydrogen levels a could be generated in excess' of 50% of the lower flamable limit. i

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 hydrogen generation..which is 10% of:the lower flammability limit.

3. Provide information on any site-specific lubricants. cleaning agents, or lother materials that may react with the DSC contents and environment, during the loading and unloading activities.

The responses submitted by VECTRA focused only on the NUHOMS system and did not take into account any site-specific differences. ,

14. Describe the methods used to vent the DSC and monitor hydrogen before  ;

and during welding. grinding, or cutting operations associated with loading or unloading activities.

5. Justify the precautionary measure that would allow the H a levels to ,

l- reach 50% of the lower flammability limit prior to stopping welding or  !

grinding activities. '

As stated in RAI Question No. 2. VECTRA's responses to Bulletin 96-04

.did not contain a discussion of the recommended margin of safety that i should exist between the amount of hydrogen produced and the j flammability limit. The staff has previously accepted a 0.4% limit of 1 hydrogen generation, which is 10% of the lower flammability limit.

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