ML20141J041

Forwards Request for Addl Info Re Application Dtd 970414, Requesting Amend to Coc for Paducah Gaseous Diffusion Plant to Revise Technical Safety Requirement (Tsr) 2.4.4.12

ML20141J041
Person / Time
Site:	07007001
Issue date:	05/23/1997
From:	Horn M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	John Miller UNITED STATES ENRICHMENT CORP. (USEC)
References
TAC-L32027, NUDOCS 9705270214
Download: ML20141J041 (3)

Text

. . _. __ .

4, May 23, 1997 l

Mr.-Jame's H. Miller l

Vice President, Production yy U. S. Enrichment Corporation ,

, 2 Democracy Center l

! 6903 Rockledge Drive Bethesda, MD 20817 {

i

SUBJECT:

PADUCAH CERTIFICATE AMENDMENT REQUEST - CASCADE CELL TRIP FUNCTION REQUIREMENTS (TAC NO. L32027)

Dear Mr. Miller:

This refers to your application dated April 14,1997, requesting an amendment to the Certificate j of Compliance for the Paducah Gaseous Diffusion Plant to revice Technical Safety Requirement (TSR) 2.4.4.12, Cascade Cell Trip Function, to provide clarification of battery cell parameters, to provide for altemate means of verifying functionality of the cascade cell trip circuit and to provide a definition of planned and unplanned cell shutdown.

Our review of your application has identified additional information that is needed before final action can be taken on your request. The additionalinformation, specified in the enclosure, should be provided within 21 days of this letter Please reference the above TAC No. in future

correspondence related to this request.

If you have any questions regarding this matter, please contact me at (301) 415-8126.

Sincerely,

! Original Signed By 9

Merri Horn I Project Manager Enrichment Section Special Projects Branch Division of Fuel Cycle Safety and Safeguards, NMSS Docket 70 7001 Certificate GDP-1 I !

Enclosure:

As stated cc: Mr. Steve Polston, PGDP Mr. Randall DeVault, DOE i DISTRIBUTION: w/ encl. (Control No. 230S) 3 Docket 70-70017 NRC File Center *? PUBLIC Rill KO'Brien, Rill NMSS r/f FCSS r/f SPB r/f GShear, Rlli G:\RAICTF.MH OFC SPB b h4 SRlb NAME om:ii cadley e tin lDATE 5 A//97 " 5 M,97 @s7 C = COVER E a COVER & ENCLOSURE N = NO COPY OFFICIAL RECORD COPY C

01 PDR, h

i Request for AdditionalInformation Application Dated April 14,1997 United States Enrichment Corporation  ;

Paducah Gaseous Diffusion F: ant Docket 70-7001 I

i Please provide the following information:

l

1. Your letter indicates that the attemate method will be used to demonstrate operability for cells 1 that were shutdown at transition. However, both enclosure 1 and the revised TSR exempt these

, cells and would allow startup without conducting the altemate test. Please clarify. If it is not your l

intent to test these cells prior to startup, explain why this is acceptable, include an indication of I the last time the cell was shutdown in a planned manner using the motor stop button or the l motor breaker pistol grip.

2. While the SAR may not explicitly state that the 5 yearinterval for testing the manual shutdown of each cell was utilized as an assumption in the accident analysis, it is not clear that it was not used as a supporting basis. The SAR states that the reliability of the manual cell shutdown system is verified through manual shutdown of each cell within a 5-year period. In addition, 1 USEC commetted to and is expected to conduct its operations in accordance with the SAR, j including the 5 year surveillance frequency. The manual cell shutdown system is one of the l means relied on to mitigate a possible UF release. While the SAR may refer to the diversity cf the manual cell shutdown system, USEC chose the motor stop button / motor breaker pistol grip as the method to place in the TSR. Other methods cannot be relied on without making the mechanism for the method a safety system.

3. Include in enclosure 1 a discussion as to why the altemste test is equivalent.

4. Revise the TSR to incorporate the changes approved by Amendment 1.

5. The definition of planned shutdown is unacceptable as written. The definition implies that any manual method for cell shutdown is acceptable as long as it is covered by a procedure. The TSR specifies a particular method for planned cell shutdowns. The definition should provide some indication of the purpose for the shutdown, such as for preventive maintenance, conduct of surveellances, or operational checks.

l- 6. All planned shutdowns should be conducted using the motor stop button / motor breaker pistol grip. If for some reason (e.g., operator error or down at transition) the cell was shutdown using some other method, the altemative method for demonstrating operability would be acceptable.

The TSR surveillance should be revised to reflect this situation.

7. While your discussion indicates that the safest courte of action in the event of a complete building failure may be to retum the cells to service in an expeditious manner, this position

- appears to be primarily related to operational vice safety needs. Cascade system cooling, UF.

i freeze out and deposition are primarily operational problems. Also, it is not clear why an

operability check for cell trip could not be conducted for unplanned shutdowns involving fewer i cells. Your discussion only addressed a large number of cells (e.g., building power failure).

j Conduct of the attemative operability test prior to restart of cells shutdown in an unplanned 1

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ENCLOSURE i

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manner could count toward the 5 year surveillance frequency so that a cell would not need to shutdown to meet the surveillance requirement. Expand your discussion to address the situation where only a few cells are shutdown in an unplanned number. How frequently have unplanned shutdowns occurred that affected a large number of cells?

8. Please provide the assumptions and bases for your assessment that only 0.1% of the battery capability was required to assure the trip system operability.

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