ML20248A899

Submits One Potential Abnormal Occurrence, Seismic Risk from Liquid U Hexafluoride at Withdrawal Facilities at Paducah Gaseous Diffusion Plant, Per 980423 Request.Ao Is Provided in Wordperfect File on Attached Disk.W/O Disk

ML20248A899
Person / Time
Site:	07007001
Issue date:	05/22/1998
From:	Cool D NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Rossi C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD)
References
NUDOCS 9806010084
Download: ML20248A899 (3)

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L May 22, 1998 MEMORANDUM TO: Charles E. Rossi, Director Safety Programs Division, AEOD ,

FROM: Donald A. Cool, Director (orig, signed by)

Division of Industrial and Medical Nuclear Safety, NMSS 1

SUBJECT:

POTENTIAL ABNORMAL OCCURRENCE AND

• OTHER EVENTS OF INTEREST" FOR THE SECOND QUARTER FISCAL YEAR 1998 I am responding, for NMSS, to your memorandum dated April 23,1998, " Request for Abnormal Occurrence and 'Other Events of Interest' input for the Second Quarter Fiscal Year ,

1998." NMSS has one potential AO (Attached), " Seismic Risk from Liquid Uranium )

Hexafluoride at the Withdrawal Facilities at the Paducah Gaseous Diffusion Plant." The potential AO is provided in a Wordperfect file on the attached disk.

Attachment:

As stated CONTACT: Gary W. Purdy NMSS/IMNS (301)415-7897 /

DISTR!BUTION: IMNS-7034 A/f g g RECORD NOTE - COORDINATED WITH:

NMSS r/f PDR: YES X NO DOCUMENT NAME: o.umn 7034 gwp i To receive a copy of this document, indicate in the box:

"C"= Copy w/o attlenet "E" = Co ay w/att/enet"N" = No copy Ye previous concurrence OFC OB OB m , . IMNf!Pr#

NAME GPurdy/k SMo$e Lkhs b DATE 5/20/1998 -5/1 0 /1998 Sh '/1998 5/Z1J1998 OFF!CIAL RECORD COPY- j

& '9906010004 903522

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. Potential Abnormal Event 98-X Seismic Risk from Liquid Uranium Hexafluoride at the Withdrawal Facilities at the Paducah Gaseous Diffusion Plant The following information pertaining to this event is also being reported concurrently in the Federa/ Register. Appendix A (see Part lil, "For Fuel Cycle Facilities") of this report notes that l

a major condition or significant event not considered in the license /cedificate that requires immediate remedial action can be considered an AO.

Date and Place - February 18,1998; Paducah Gaseous Diffusion Plant (Paducah), a uranium enrichment plant , operated by Lockheed Martin Utility Services (LMUS) for the United States Enrichment Corporation (USEC) and located about 16 kilometers (10 miles) west of Paducah, I Kentucky.

Nature and Probable Consequences - On October 31,1997, USEC submitted a certificate )

amendment request that provided an updated Safety Analysis Report (SARUP), including a new accident analysis, for Paducah. The seismic accident analysis identified that equipment (piping, condensers, and accumulators) in the withdrawal facilities containing liquid uranium hexafluoride (UF.) could fail at a seventy-year return earthquake (0.05 g peak ground acceleration (pga)) rather than the 250-year return design basis earthquake (0.15 g pga).

However, the accident analysis consequences were identified as minimal due to the assumptions made in the accident analysis. A Nuclear Regulatory Commission (NRC) request

, for additional information (RAI) dated February 5,1998, identified questions about the conservative nature of assumptions for the seismic accident analysis. In response to the RAI, USEC confirmed that the seismic accident analysis assumption of no liquid UF in the withdrawal facilities' accumulators underestimated the potential source term for the seismic accident analysis.

The accumulators are normally empty and serve only as a reservoir for liquid UF, when cylinders are changed after being filled or during periods of equipment problems or surveillance. However, with no operational restrictions on the amount of liquid UF,in the accumulators, a seismic event could occur with the accumulators full, Consequences from a 0.05 g pga earthquake with full accumulators in the withdrawal facilities could include onsite ,

fatalities and significant offsite injuries from exposure to the released UF. and reaction  !

l products. ]

l Cause or Causes - The cause of this event was an inadequate seismic design for the facility i and an inadequate accident analysis that did not consider the full range of allowable operations i of the withdrawal facilities.

l l-l Actions Taken to Prevent Recurrence Licensee / Certificate Holder - Immediate corrective sctions included restricting operations in the withdrawal facilities to limit the amour,t of liquid UF available for release. Long term ,

corrective actions are to install seismic modifications that will allow the withdrawal facilities' l equipment to withstand a design basis earthquake. USEC has committed to completing the I seismic modifications by September 30,1998.

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- 2 NRC - An immediately effective confirmatory order incorporating the immediate and long term corrective actions was issued and potential escalated enforcement action is being considered.

Attachment 4

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