ML20133B685

Discusses Concerns Re Certificate Amend Request for Rev to Definition of Withdrawal Stations Standby Operational Mode for Ports

ML20133B685
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant
Issue date:	12/31/1996
From:	Pierson R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	John Miller UNITED STATES ENRICHMENT CORP. (USEC)
References
TAC-L32006, NUDOCS 9701060081
Download: ML20133B685 (2)

Text

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_p i UNITED STATES

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p NUCLEAR REGULATORY COMMISSION l j - WASHINGTON, D.C. 30e064001 '

% + December 31, 1996 F ,

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j Mr. ' James H. Miller l L Vice President, Production l U. S. Enrichment Corporation 4 2 Democracy Center 4- 6903 Rockledge Drive  !

Bethesda, MD 20817-

SUBJECT:

CERTIFICATE AMENDMENT REQUEST - PORTSMOUTH GASEOUS DIFFUSION >

PLANT WITHDRAWAL STATIONS STANDBY OPERATIONAL MODE (TAC NO. l i L32006) 1

. i

Dear Mr. Miller:

This refers to your letters dated November 8,1996 and December 13,1996, regarding a ' l 1- revision to the definition of the Withdrawal Stations Standby Operational Mode for the Portsmouth Gaseous Diffusion Plant (PORTS). This letter also responds to a request made - ,

! by Mr. Mark Smith (USEC), during an open meeting at NRC Headquarters on December 23,  !

1996, for detailed documentation of NRC concerns. j i

i PORTS certification application states in Technical Safety Requirement 2.5.1 that the withdrawal loop vent valve (s) shall be in the " closed" position in the Standby Operational l Mode. Your November 8 letter requested revision to this mode's definition to allow the I

flexibility to open the vent valves in this mode. As indicated in the PORTS Safety. Analysis )

i Report (SAR) Figure 3.2-10 entitled "ERP and LAW Flow Diagram" there are four vent lines j that vent portions of the withdrawal loop to the cascade. The NRC concern, which was

also raised during a telephone conversation with Mark Smith and PORTS personnel on l November 25,1996, and during the December 23 meeting, deals with the vent line

?- leading from the withdrawal manifold to the cascade.

i it is not clear from USEC submitted documentation that going from a closed withdrawal

! manifold vent path to an open vent path in the standby mode would not constitute a

i. significant increase in risk of a criticality accident. That is, neither your TSR amendment i request package nor the PORTS SAR damonstrates that this TSR change would not

significantly increase the probability of significant wet air (moderator) introduction, via the

! one inch withdrawal manifold vent line, into the cascade (unsafe geometty), which may j i contain deposits of solid enriched uranium exceeding safe mass. Based on the PORTS j

SAR Figure 3.2-10, while the pigtail is not attached to the withdrawal manifold, an

- inadvertent opening of the withdrawal manifold safety valve may provide a pathway for d

significant wet air introduction intn the cascade. However, the piping and instrumentation

' diagram (p&id) of the withdrawal loop, which has not been submitted to the NRC but was 4 made available during the December 23 meeting, showed additional valves which, if - r

! correctly operated, would maintain the safety margin described in your approved M f b ()

ap;)lication.  ;

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i Mr. James H. Miller 1 It is also not clear from the documentation included in the subject TSR amendment request that, as mentioned by USEC staff in the December 23 meeting, the only vent path that is

needed to be open in the standby mode is the one leading from the compressors to the l

)

cascade. If this is indeed the case, then it should t,e accordingly reflected in the standby i mode definition as agreed to in the December 23 meeting.

l i

Please be advised that since the documented information provided does not resolve the issue concerning criticality safety, the NRC staff is unable to conclude that there would be no significant reduction in safety in granting your requested change to your approved certificate application, if you have questions, please contact Mr. Yawar Faraz at (301) 415-8113.

Sincerely, Original Signed By Robert C. Pierson, Chief Special Projects Brench Division of Fuel Cycle Safety and Safeguards, NMSS  ;

I cc: J. Dale Jackson, DOE i

Docket 70-7002 l Certificate GDP-2 DISTRIBUTION: (Control No. 030S)

NRC File Centeri PUBLIC DAHoadley (2) Rill KO'Brien, Rill NMSS r/f FCSS r/f WSchwink,FCOB CCox, Rill MHorn FCEB r/f OGC JWang GShear, Rill Docket 70-7002 G:WNTAMND1.YHF OFC SPB d- \SPB [ SPB C. SPBn NAME YFarabi DH ey in Rhson DATE C = COVER ik /35/96 [ / /9 kE = COVER & ENCLOSURE

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