ML22174A077

American Centrifuge Plant - Summary of Non-Administrative Changes to the Criticality Computer Code Validation Report

ML22174A077
Person / Time
Site:	07007003, 07007004
Issue date:	06/20/2022
From:	Karen Fitch American Centrifuge Operating, Centrus Energy Corp
To:	John Lubinski Document Control Desk, Office of Nuclear Material Safety and Safeguards
References
ACO 22-0049
Download: ML22174A077 (3)

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June 20, 2022 ACO 22-0049 ATTN: Document Control Desk John W. Lubinski, Director Office of Nuclear Material Safety and Safeguards U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 American Centrifuge Lead Cascade Facility and American Centrifuge Plant Docket Numbers 70-7003 and 70-7004; License Numbers SNM-7003 and SNM-2011 Summary of Non-Administrative Changes to the Criticality Computer Code Validation Report

Dear John Lubinski:

In accordance with SNM-2011, Materials License, condition 27, American Centrifuge Operating, LLC (ACO) hereby submits to the U.S. Nuclear Regulatory Commission (NRC) a summary of changes to ACO' s EE-3101-0013, Rev. 1, NCS Code Validation ofSCALE 6. 2. 3 and Cross Section Set v7-252 for keff Calculations as Enclosure 1 of this letter.

These changes have been reviewed in accordance with 10 CFR 70.32 and 10 CFR 70.72 and have been determined not to reduce the margin of subcriticality for safety and not require prior NRC approval. A revised validation report will be available upon request.

If you have any questions regarding this matter, please contact me at (740) 897-3859.

Sincerely,

(")'~{'~~,\-ch K~Mch Regulatory Manager cc (with enclosure, unless otherwise noted):

Y. Faraz, NRC HQ (Enclosure)

S. Harlow, DOE HQ N. Pitoniak, NRC Region II L. Pitts, NRC Region II (Enclosure)

J. Tobin, NRC HQ (Enclosure)

T. Vukovinsky, NRC Region II American Centrifuge Operating, LLC 3930 U.S. Route 23 South - P.O. Box 628 PikAtnn OH 4!iRR1

Enclosure 1 to ACO 22-0049 Summary of Changes to EE-3101-0013, Rev.1,NCS Code Validation ofSCALE 6.2.3 and Cross Section Set v7-252 for kerr Calculations Information Contained Within Does Not Contain Export Controlled Information Reviewing Official: _ _ _ _ _#_1_0_3~8,~A_C_O_ _ __

Date:* 6/20/2022

Summary of Changes in EE-3101-0013, Rev. 1

1. Added a revision log to the document to provide a mechanism to clearly document the changes made during each revision to the document.

2. Revised the Material Area of Applicability (AoA) provided in Section 9.1 to exclude all standard compositions that use nuclide ID 9001001 (i.e., h-poly, norparl3, paraffin, polyethylene, polyvinylcl, pvc, tbp, and kerosene). These standard compositions are excluded based on SCALE User Notice dated February 26, 2021.

3. Added the SCALE User's Notice, dated February 26, 2021, to the References.

Background Information The Radiation Safety Information Computational Center (RSICC) issued a SCALE User Notice on February 26, 2021, to communicate an issue in SCALE 6.1.0-6.1.3 and 6.2.0-6.2.4. The User Notice

states, "A defect has been found in SCALE's hl-poly incoherent elastic scattering which can cause k-eff underprediction approaching 1% in criticality problems with polyethylene as the primary moderator."

The issue was entered into American Centrifuge Operating, LLC' s (ACO) Corrective Action Program.

In response to the SCALE User Notice, ACO performed a review of nuclear criticality safety (NCS) calculations to identify any case that used standard composition H-POL Y. By extension searches for any use ofNuclide ID 9001001 were performed by NCS. The searches included all calculations used to establish the basis for subcriticality and no cases were identified that included Nuclide ID 9001001.

A separate action was established to pro grammatically prohibit use of standard compositions that use SCALE ID 9001001 (e.g., H-POL Y and POLYETHYLENE). A search through the benchmark cases revealed that no case used H-POL Y; however, nuclide ID 9001001 was included in cases that use standard composition POLYETHYLENE. That material was included (with nuclide ID 9001001) in benchmarks IMF-022-02, IMF-022-03, IMF-022-04, IMF-022-05, and IMF-022-07. A review of the results for those cases in Table 40 ofEE-3101-0013 does not indicate an underprediction inkeff. Since these benchmarks include nuclide ID 9001001, the effect of the cross-section bias for nuclide ID 9001001 is represented to some extent in the bias and bias uncertainty calculated in EE-3101-0013.

Nevertheless, the standard compositions that use nuclide ID 9001001 were excluded from the AoA in EE-3101-0013 for conservatism.