ML22004A170
| ML22004A170 | |
| Person / Time | |
|---|---|
| Site: | 07003103, 07109362 |
| Issue date: | 01/10/2022 |
| From: | Bernie White Storage and Transportation Licensing Branch |
| To: | Geoffrey Miller Division of Fuel Management |
| B WHITE NRC/NMSS/DFM/STLB 3014156577 | |
| Shared Package | |
| ML22004A169 | List: |
| References | |
| EPID L-2021-LRM-0119 | |
| Download: ML22004A170 (5) | |
Text
MEMORANDUM TO:
Geoffrey Miller, Acting Deputy Director Division of Fuel Management Office of Nuclear Material Safety and Safeguards FROM:
Bernard White, Senior Project Manager Storage and Transportation Licensing Branch Division of Fuel Management Office of Nuclear Material Safety and Safeguards
SUBJECT:
SUMMARY
OF DECEMBER 13, 2021, MEETING WITH LOUISIANA ENERGY SERVICES TO DISCUSS A PROPOSED EXEMPTION FOR THE MODEL NO. DN30 PACKAGE
Background
On December 13, 2021, a virtual, meeting was held, at the request of the Louisiana Energy Services doing business as Urenco USA (UUSA) with the U.S. Nuclear Regulatory Commission (NRC) staff to discuss a proposed exemption for shipment of uranium hexafluoride (UF6) enriched to 10 weight percent in the uranium-235 (235U) in the Model No. DN30 package. The list of meeting attendees is provided as Enclosure 1. The presentation used in the meeting is provided as Enclosure 2.
UUSA requested the meeting to kick off discussion with the NRC on its approach for a potential exemption request. During the meeting UUSA discussed its approach to the criticality safety evaluation and the environmental report. UUSA stated that it intends to pursue an exemption to the regulations in Title 10 of the Code of Federal Regulations (10 CFR) 71.55(g)(4) to the 5 weight percent limit on use of an exception to the single package criticality analysis in 10 CFR 71.55(b) to be able to transport UF6 enriched up to 10 weight percent 235U and an amendment to add the exemption to its facility license through new license conditions. In addition to the exemption, UUSA will be requesting the deviations from Certificate of Compliance No. 9362.
CONTACT:
Bernard White, NMSS/DFM (301) 415-6577 January 10, 2022 Signed by White, on 01/10/22
G. Miller 2
Discussion In the exemption request, UUSA will not be requesting any changes to the design of the packaging, however it will be providing new criticality and shielding analyses to support the exemption and associated deviations from the certificate. UUSA said it will be requesting the following deviations from Certificate of Compliance No. 9362, for the Model No. DN30 package:
increase the maximum enrichment from 5 to 10 weight percent 235U.
revise the Condition No. 6 in the certificate which requires the 30B cylinder to conformance to American National Standards Institute (ANSI) N14.1, Nuclear Materials Uranium Hexafluoride - Packagings For Transport, which limits the maximum enrichment in 30B cylinders to 5 weight percent 235U. NRC staff notes that International Standards Organization Standard No 7195, Nuclear energy Packaging of uranium hexafluoride (UF6) for transport also limits the maximum enrichment to 5 weight percent 235U and is reference in Condition No. 6.
increase the criticality safety index.
In its discussion, UUSA provided an overview the criticality analysis it has performed to-date to support the exemption request, including analyses for a single package and arrays of packages.
In discussing these analyses, UUSA stated that it will
factor in the mass of UF6, which may be less than the maximum loading of 2277 kg of UF6 in a cylinder,
evaluate a more realistic representation of the hydrogenated uranium residue sphere, and
consider a potential reduction of the 5 percent administrative margin on the upper subcritical limit.
UUSA plans on using Oak Ridge National Laboratory Report No. ORNL/TM-2021/2043, Analysis of the 30B UF6 Container for Use with Increased Enrichment for developing bounding conditions for the criticality analysis base case. UUSA performed its criticality analyses for the maximum enrichment of 10 weight percent 235U.
In its single package analysis, UUSA modeled the 30B cylinder with and without the DN30 overpack for its single package analyses for 10 CFR 71.55(b), (d), and (e). None of these models consider the hydrogenated uranium residue and were evaluate using the maximum loading of the 30B cylinder, 2277 kg UF6. UUSA reported that is maximum keff, including uncertainty is approximately 0.7, with the model that omits the DN30 overpack being the most reactive.
For its array analysis for normal conditions of transport, it considered 30 packages in 2x15 array for the 5N array analyses. The 30B cylinders in the model were surrounded by a water layer that optimizes keff. The keff for this array is approximately 0.92. UUSA increased the array size to a 2x19 array, which increased keff to approximately 0.95.
For the array analyses after the tests for hypothetical accident conditions, UUSA modeled 14 packages in a 2x7 array which included the hydrogenated uranium residue. UUSA modeled the hydrogenated uranium residue as an 11.4 kg sphere in the form of UO2F2-2H2O-2HF, with the hydrogen fluoride (HF) mixed homogenously in the UF6. UUSA stated that the keff for this array is approximately 0.90. Based on 2 papers it cited, UUSA proposed to not model a HF spherical shell around the hydrogenated uranium residue and used a bounding H/U ratio of 6. UUSA stated that is also considering requesting a lower maximum authorized mass of UF6 to reduce the criticality safety index.
G. Miller 3
UUSA briefly discussed its proposal to use an upper subcritical limit of 0.948, which corresponds to an administrative margin on 0.4. NRC guidance in NUREG-2216, Standard Review Plan for Transportation Packages for Spent Fuel and Radioactive Material: Final Report, states that NRC accepts an administrative margin of 0.5. While this is a deviation from guidance, NRC told UUSA that it will need to provide justification for its reduced administrative margin. NRC further stated that there are not a lot of critical experiments that can be used to benchmark this criticality analysis, therefore it might be difficult to justify a reduction in the administrative margin.
Finally, UUSA described, at a very high level, the items it proposes for the environmental report.
In the discussion of alternatives, the NRC stated that it would expect UUSA to discuss the use of the Model No. DN30-X (Docket No. 71-9388) as an alternative. The package design for the Model No. DN30-X (Docket No. 71-9388) is under review by the NRC for transport of UF6 up to 20 weight percent 235U. NRC stated that based on the proposed schedule, the DN30-X package could be approved before NRC receives an exemption request from UUSA.
NRC asked UUSA about its proposed schedule for requesting the exemption. UUSA stated that it was considering a December 2022 submittal date.
Docket Nos. 70-3103 and 71-9362 EPID No. L-2021-LRM-0119
Enclosure:
- 1. Meeting Attendees
- 2. Meeting Presentation
SUBJECT:
SUMMARY
OF DECEMBER 13, 2021, MEETING WITH LOUISIANA ENERGY SERVICES TO DISCUSS A PROPOSED EXEMPTION FOR THE MODEL NO.
DN30 PACKAGE. DOCUMENT DATE:
DISTRIBTION:
NRC Meeting Attendees K. Jamerson, NMSS ADAMS Accession No.ML22004A169 ML22004A170 (Memo) ML22004A171(Enc1)
ML22004A172 (Enc2)
OFFICE NMSS/DFM NMSS/DFM NMSS/DFM NAME BWhite SFigueroa YDiaz-Sanabria DATE 1/10/2022 1/5/2022 1/6/2022 January 10, 2022
ML22004A169; Memo ML22004A170 OFFICE NMSS/DFM/STLB NMSS/DFM/STLB NMSS/DFM/CTCFB NMSS/DFM/STLB NAME BWhite SFigueroa YDiaz-Sanabria BWhite DATE Jan 4, 2022 Jan 6, 2022 Jan 6, 2022 Jan 10, 2022