ML24032A322
| ML24032A322 | |
| Person / Time | |
|---|---|
| Site: | OPTIMUS-L |
| Issue date: | 02/06/2024 |
| From: | Storage and Transportation Licensing Branch |
| To: | NAC International |
| Shared Package | |
| ML24032A319 | List: |
| References | |
| EPID L-2023-LLA-0177 | |
| Download: ML24032A322 (2) | |
Text
SAFETY EVALUATION REPORT Docket No. 71-9390 Model No. OPTIMUS - L Package Certificate of Compliance No. 9390 Revision No. 3
SUMMARY
By letter dated December 18, 2023 (Agencywide Documents Access and Management System
[ADAMS] Accession No. ML23352A345), NAC International (NAC or the applicant) submitted an amendment request to clarify the maximum activity limits for key individual gamma-emitting contents (e.g., Co-60 and Cs-137 including Ba-137m daughter product) and neutron-emitting contents (e.g., Cf-252 and Cm-244).
The changes in Revision No. 4 of the CoC are limited to Table 4 in Condition No.5.(b)(2). There are no changes to the drawings, design features, operating and maintenance procedures of the OPTIMUS-L packaging.
Based on the statements and representations in the application, and the conditions listed in the CoC, the U.S. Nuclear Regulatory Commission staff (the staff) concludes that the package meets the requirements of Title 10 of the Code of Federal Regulations (10 CFR) Part 71.
EVALUATION
The purpose of this evaluation is to verify that the proposed updates to the permitted isotopes in the shielding design of the NAC OPTIMUS-L package meet the dose rate limits set forth in 10 CFR 71.47(b) and 71.51(a)(2) under both normal and accident conditions of transport under exclusive use. This evaluation documents the staffs review of the updates to the permitted isotopes in the shielding analysis for the OPTIMUS-L package.
For this proposed application, the applicants calculations determine dose rate/Ci results and activity limits for the OPTIMUS-L using 10 CFR Part 71 Appendix A to collapse parent and short-lived daughter decay chains.
The applicant used Table A-1 of 10 CFR Part 71 to determine the short-lived daughter isotopes collapsed to their parents and the isotopes retained even though collapsed. Footnote a of Table A-1, which lists the contributions from short term daughter nuclides, is used to determine which isotopes are collapsed, but if the daughter isotope is included in Table A-1, that means that the daughter isotope is not collapsed.
For the activity of Cs-137 (half-life of 30 years), the staff agrees it is preferable to have those including the Ba-137m daughter instead of being accounted separately because Ba-137m has a half-life of only 2.55 minutes (153 seconds) and quickly decays down to its stable ground state.
Also, the amount of the radionuclides present in Ba-137m is small, at most 95% of the Cs-137 activity, based on the decay scheme.
Enclosure 2 Table 6-6 of the application shows the maximum external dose rate for the major isotopes in a package. Cases listed for each isotope were analyzed individually using the method approved in Revision 0 (ML20266G182) of the application and each case is for one package containing the maximum activity of the respective isotope.
The staff reviewed the parent and short-lived daughter decay chains from Table A-1 of 10 CFR Part 71 which are summarized in Table 4-1 of the application. Also, the staff reviewed the branching fractions taken from ORNL/TM-13624 and listed in Table 4-2 of the application.
The staff reviewed and found acceptable the applicants analysis where the applicant calculated the dose rate per Ci of a parent/daughter chain which is the dose rate per Ci of the parent plus the summation of the dose rate per Ci of each ith daughter multiplied by its branching fraction.
The applicant limited the activity using the dose rate per Ci values and the applied limits (i.e.,
180 mrem/hr at the package surface and 9 mrem/hr at 2 meters).
The staff concludes that the proposed update to the permitted isotopes in the shielding design of the OPTIMUS-L, when used as described in the application, is in compliance with 10 CFR Part 71 and that the applicable design and acceptance criteria have been satisfied. The staff has reasonable assurance that the OPTIMUS-L design will provide safe transportation of transuranic (TRU) waste. This finding is based on a review that considered the regulation itself, the appropriate regulatory guides, applicable codes, and standards, the applicants analysis, and acceptable engineering practices.
Based on its review of the statements and representations provided in the application, the staff has reasonable assurance that the shielding evaluation is consistent with the appropriate codes and standards for shielding analyses and NRC guidance. Therefore, the staff finds that the package design and contents satisfy the dose rate limits in 10 CFR Part 71.
CONDITIONS
Condition No. 5(b)(2), Table 4, has been revised for the TRU Waste and irradiated fuel waste (IFW) activity limits for key isotopes.
Condition No. 14 has been deleted since Revision No. 2 of the certificate could no longer be used with the previous Table 4, now corrected in Revision No. 3 of the certificate.
Condition No. 15 has been renumbered to No. 14. The expiration date of the certificate is not changed.
CONCLUSION
Based on the statements and representations in the application, the staff finds that these changes do not affect the ability of the package to meet the requirements of 10 CFR Part 71.
Issued with CoC No. 9390, Revision No. 3.
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