ML20197G668

Informs That NRC Cannot Endorse Usecs Use of Scale 4.3 Codes & Cross Sections at Present Time.Nrc Has Identified Listed General Areas in Which Addl Info Is Needed.Info Should Be Provided within 30 Days of Ltr

ML20197G668
Person / Time
Site:	Portsmouth Gaseous Diffusion Plant, 07007001
Issue date:	12/04/1998
From:	Galloway M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Woolley R UNITED STATES ENRICHMENT CORP. (USEC)
References
TAC-L32076, NUDOCS 9812100057
Download: ML20197G668 (3)

Text

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pa%q\ UNITED STATES g g NUCLEAR REGULATORY COMMISSION

• WASHINGTON, D.C. 20 % 5 4001

. g ,$ Decernber 4,1998 Mr. Robert Woolley Manager, AVLIS Nuclear Regulatory Policy and Licensing U.S. Enrichment Corporation Two Democracy Center 6903 Rockledge Drive Bethesda, MD 20817

SUBJECT:

AVLIS CRITICALITY CODE VALIDATION REPORT (TAC NO. L32076)

Dear Mr. Woolley:

In a letter dated October 22,1998, "AVLIS Criticality Code Validation," L-98-011, the United States Enrichment Corporation (USEC) provided further discussion of the applicability of the Atomic Vapor Laser Isotope Separation (AVLIS) Criticality Code Validation Report submitted to the U. S. Nuclear Regulatory Commission (NRC) on April 22,1998, and the general rules of practice for AVLIS criticality safety analyses that will be incorporated into the nuclear criticality safety chapter of the AVLIS iicense application. USEC concluded that the selected benchmarks adequately cover AVLIS materials, configurations of interest, and ranges of applicability, including the intermediate fission energy spectrum. Based upon these conclusions, USEC requested endorsement of the SCALE 4.3 codes and cross sections as applied to AVLIS materials and systems.

On November 4,1998, NRC technical staff toured the AVLIS Demonstration Pilot located at the Lawrence Livermore National Laboratory. This tour served to greatly facilitate the understanding of AVLIS-specific issues; however, NRC cannot endorse USEC's use of the SCALE 4.3 codes and cross sections at this time. Although NRC finds merit with USEC's philosophy and approach to criticality safety, NRC has concluded that further information from USEC is necessary to determine the acceptability of the report for the proposed area of applicability. NRC recognizes that it is not necessary or currently possible for a benchmark set to cover every parameter over the full range of possibilities. However, it is NRC's expectation that USEC evaluate sufficient experimental evidence to support statistically significant trends for the areas of requested operation or limit the validation range to those areas where sufficient data exists. NRC has identified tne following general areas that require further USEC review and discussion:

(1) Analysis and review of process conditions occurring in the intermediate energy range and the adequacy of current experimental evidence to support these cases; (2) Application of appropriate bias and margins of safety for the extension of enrichment values in the range of 5 - 10 weight percent; D

(3) Review of multiple parameter interdependence and perturbation for those parameters specific to the AVLIS process; and r

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(4) Adequacy of available cross-sections for high temperature metals and systems that are part of the AVLIS process or supporting rationale that such conditions are not possible.

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DEC 4 ins J. H. Miller, USEC 2 (4) For the Portsmouth site, please identify all areas that are required to be monitored by a CAAS, but where CAAS alarm audibility may not be adequate. For example, provide the measures relied upon to ensure adequate CAAS audibility in the cascade cell enclosures for all cell operational modes.

The additional information requested should be provided within 30 days of this letter.

However, a more expedient response would facilitate our review given that resources are currently available to address these requests. NRC recognizes that considerable time has passed since your original requests were submitted and appreciates your prompt response to permit closure of these items as quickly as possible.

If you have any questions regarding this matter, please contact the respective project manager I for the associated site.

Sincerely, Original Srgned ey Melanie A. Galloway, Chief Enrichment Section l Special Projects Branch Division of Fuel Cycle Safety ,

and Safeguards, NMSS i l

Docket No. 70-7001, 70-7002 I

cc: Mr. Morris Brown, Ports Mr. Howard Pulley, PGDP Mr. Steve Toelle, USEC DISTRIBUTION Docket File 70-7001,7002 LNRC5e ConserT' l

FCSS r/f RIII Public PHiland, Rill JJacobson, Rill

, FSPB r/f KO'Brien, RIII NMSS r/f DHartland, RIII l

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• Picase see previous concurrence

• SPB C SPB 6 SPB, C SPB C SPB C l JDavis:ij JMuszkih Nrn hh, hSyhway 12/ 03 /98 l)/ L /98 lA /h /98 (7./Y/98 / Y/98 1 C= Cover E= Cover & Enclosure N= No Copy OITICIAL RECORD COPY

4, J. H. Mill:r, USEC 2 measures relied upon to ensure adequate CAAS audibility in the cascade cell enclosures for all cell oper,ational modes.

The additionalinformation requested should be provided within 30 days of this letter. However, a more expedient response would facilitate our review given that resources are currently available to address these requests. NRC recognizes that considerable time has passed since your original requests were submitted and appreciates your prompt response to permit closure of these items as quickly as possible.

If you have any questions regarding this matter, please contact the respective project manager for the associated site. '

Sincere ,

M anie A. Galloway, Chief F/irichment Section

,Special Projects Branch

/ Division of Fuel Cycle Safety and Safeguards, NMSS Docket No. 70-7001,70-7002 cc: Mr. Morris Brown, Ports e Mr. Howard Pulley, PGDP j Mr. Steve Toelle, USEC g j

/

s DISTRIBUTION /

Docket File 70-7001,7002 WRC FS Center FCSS r/f Rin Public PHiland, RIII JJacobson. RIII FSPB r/f KO'Brien, RIII NMSS r/f DHartland, RIII cADavis\amaster\portskaas.rai SPB C- SPB SPB SPB SPB ODavis:ij JMuszkiewicz MHorn YFaraz MGalloway S /3 68 / M8 / M8 / M8 / M8 C= Cover E= Cover & Enclosure N= No Copy OmCIAL RECORD COPY

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