ML20207R756

Submits Addl Info Re Nbs Reactor Use of Highly Enriched Fuel,Per 870211 Request.Majority of Programs at Nbs Reactor Require Current Enrichment Levels.Lowering of Enrichment Level Below 80 % Unacceptable

ML20207R756
Person / Time
Site:	National Bureau of Standards Reactor
Issue date:	03/10/1987
From:	Rozier Carter NATIONAL INSTITUTE OF STANDARDS & TECHNOLOGY (FORMERL
To:	Dosa J Office of Nuclear Reactor Regulation
References
NUDOCS 8703180102
Download: ML20207R756 (2)

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• UNITED f TATE] DEPARTMTNT OF COMMERCE National Bureau of Standards Gaithersburg.Meryland 20899 k*4res 08 Please Note: New Telephone Numbers (301) 975-6210 FTS 879-6210 March 10, 1987 Mr. John Dosa, Project Manager Standardization and Special Projects Directorate Division of PWR Licensing-B Office of Nuclear Reactor Regulation

. United States Nuclear Regulatory Commission Washington,- DC 20555

Subject:

Additional Information, Docket No. 50-184 Below is the additional information you requested in your letter of February 11, 1987.

The need for the highest flux and best spectrum to carry out vital national and standards programs has been established in prior transmittals. In fact, the original decision to locate a research reactor at the National Bureau of Standards was precisely for those same reasons in order to provide the United States with a fully competitive facility. Accordingly, the NBS reactor, the last major research reactor built in this country, was designed with the most advanced features and facilities. One of the principal considerations in the design was the use of highly enriched fuel.

It is clear that the greater the reduction in enrichment, the greater the negative impact on the programs. It has already been demonstrated that LEU cannot be tolerated. Obviously, the majority of the programs at the NBSR would benefit from the highest enrichment levels. Already many of the programs are at or near their threshold even with existing enrichment.

Furthermore, a change in enrichment would require recalibration of several standard facilities, a time consuming operation that would render these facilities useless for one or more years.

The high burnup achieved at the NBSR automatically provides a significant reduction in enrichment. Based on burnup estimates, the current 93% would be reduced to about 60% for the highest burnup element. Similarly, an enrichment of 80% would be reduced to about 40%. Finally, an initial enrichment of 50% would be reduced to below 20%, which is completely unacceptable.

NBS has carefully evaluated the impact of the above on current and future programs. Clearly, keeping current enrichment would provide the most for these programs. An enrichment of 80%, though very undesirable and limiting 0 8703180102 870310 s0 PDR ADOCK 050001S4 P pyg

. e op future advances, could be tolerated. Anything below that would adversely impact the capabilities of the NBSR, and not be in the Nation's interest.

Sincerely,

$ bh k Robert S. Carter Chief, Reactor Radiation Division 2

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