ML20197B782

Review of Criticality Safety of Proposed Surface Density Criteria in 780322 Amend Appl Reveals Need for Info of Fundamental Supporting Nature.Requested Info Should Be Provided If Vendor Wishes to Continue This Approach

ML20197B782
Person / Time
Site:	07000371
Issue date:	10/19/1978
From:	Rouse L NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
To:	Kirk W UNITED NUCLEAR CORP. (SUBS. OF UNC, INC.)
References
NUDOCS 7811080084
Download: ML20197B782 (2)

Text

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..... OCT 19 1978 FCPF:RLS70-371 SNM-368 United Nuclear Corporation Naval Products Division ATTN: Mr. William F. Kirk, Manager Nuclear & Industrial Safety 67 Sandy Desert Road Uncasville, Connecticut 06382 Gentlemen:

We have completed our nuclear criticality safety review of the proposed surface density criteria in your amendment application of March 22, 1978, Reference NIS: 78-3-34. This review revealed a need for additional information of a fundamental supporting nature as well as certain specific details of your analysis. The proposed criteria are of broad scope and rely on a lengthy derivation that does not appear to have been confirmed by sufficient calculations for individual units or sufficient calculations to check the overall method. We also note the absence of a unified listing of the off-standard conditions allowed for in the model and the magnitude of the effects of the conditions.

The overall validity of the method should be confirmed using additional KEN 0 calculations. As examples of such confirmation, reference is made to articles in Nuclear Technology by Altschuler and Schuske, "Models for the Safe Storage of Fissile Metal" (Vol.13, Feb.1972) and "A Model for the Safe Storage of Fissile Solutions" (Vol.17, Feb.1973).

More detailed comments arising from our review are given in the attach-ment. In view of the deficiencies we have identified in your applica-tion, if you wish to pursue this criticality safety approach you should provide the requested information and analyses in the form of an applica-tion revised in its entirety.

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Sinc rely,

. fuf Leland C. Rouse, Chief 7(7[hhD

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k Fuel Processing & Fabrication Branch Division of Fuel Cycle & Material Safety

Attachment:

Questions on Amendment Application of March 22, 1978, NIS:78-3-34 Docket 70-371, PC No. 78058A

' OCT 191978 QUESTIONS ON UNITED NUCLEAR CORPORATION AMENDMENT APPLICATION DATED MARCH 22, 1978 REFERENCE NIS:8-3-34, DOCKET 70-371 (CLASSIFIED) PC NO. 78058A

1. Page 3-21, para. 3.9.3.2 - Please provide justification for the adequacy of the safety margin obtained by use of the quoted limiting

" nominal" array multiplication factor, considering that there are very few supporting KEN 0 calculations, and considering that the validation document DUN-73012 indicates that a unit with a keff of 0.95 could be critical.

2. Page 3-22, para. 3.9.3.3 - Please provide backup KENO calculations to confirm that the arrays meet the quoted limiting multiplication -

factor. Examples of a reasonable approach to model confirmation may be found in Nuclear Technology, Vol.13, February 1972, p.131-147, "Models for the Safe Storage of Fissile Metal", and Vol.17, February 1973, p.110-126, "A Model for the Safe Storage of Fissile Solutions,"

by S. J. Altschuler and C. L. Schuske. ,

3. Page 3.9 5 - (a) Provide full details of the KEN 0 data which "do not indicate a positive effect of interunit moderation for moderated and reflected arrays." (b) What are the criteria for steel containment required to counteract the effect of interspersed moderation? Please provide the supporting data to justify the criteria. (c) Please explain how Figure 2 of the NSE article by J. Thomas (NSE 62,424[1977])

supports the claim that " moderated arrays" are reasonably described by metal array data. (d) Provide full details of the KEN 0 calculations to justify the stated 0.015 increment in keff from the effect of in-plant reflector conditions compared to a water reflector.

4. Page 3.9-6, Figure 3.9 (a) What is the meaning of the error bands for the KENO calculations? (b) How is it shown that the safety margins are adequate? (c) What consideration was given to the validation ,

calculations in DUN-73012?

5. Page 3-27, Figure 3.9 (a) Are the buckling values of this figure directly convertible to the volumes in Figure 3.9-2 and if not why not? (b) What extrapolation length was used in deriving Figure 3.9-5?

6. How do the calculations make allowance for the fact that units may rest on the floor or be closer to the walls and floor than the unit cell boundary (as was assumed in Thomas' analyses)?

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