Designing Flexibility into the Authorized Radioactive Contents of the 9982 Shipping Package (Midterm Report)

Technical Report · Mon Jul 15 04:00:00 EDT 2019

DOI:https://doi.org/10.2172/1542575· OSTI ID:1542575

Pittman, Chance ^[1]; Ketusky, Edward ^[1]; Nathan, Steven ^[1]

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1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

With regards to the planned contents for the 9982, three sets of radionuclides have been analyzed. A set of percentages by weight for plutonium from 3013 canisters, training sources sent in 9977’s, and americium standards from 9978’s were used as the bases for realistic contents that could be shipped in a 9982 package. Using the tables and limits located in G-BDR-A-00001 Rev. E, the calculations began by determining the mass limits for the radionuclides in each source. These mass limits were then used alongside the mass of the radionuclides in the sum-of-the-fractions methodology present in the content description. If this summation is less than or equal to one, the contents are allowed for shipment in the 9982. For the aforementioned sets, the listed radionuclides could be shipped as-is; however, the goal of the calculations is to determine the maximum content mass allowed. To do so, the percentages of weight were used to find where the summations would equal one rather than simply satisfy the inequality. By solving for the content mass when the inequality equals one, the maximum content mass is calculated, which can then be multiplied by each percent weight to get each radionuclide’s mass. The MCNP input files have also been compared to find differences between the oxide and metals forms of the radionuclides. While there are several differences present that make sense, such as oxides have more mass and a lower density due to the presence of oxygen in the oxide forms, there are other differences that are possibly unintentional. With the input files for the metals, both with and without a shielding pig, neutrons are being used in the photon models, seen by “imp:n” being present within the file instead of “imp:p”, where “imp” stands for the importance of a region for either neutrons or photons. Effectively, this results in the dose due to photons being modelled with neutrons instead, potentially resulting in the calculated dose rates being incorrect. As MCNP is proprietary, I do not have access to it here and must consult with the person handling the shielding calculations to discuss what these differences may affect and how to change them. If he remains out of the office or if fixing these files takes longer than expected, the final report may focus more on the contents while discussing these differences; however, it could potentially lack discussion on finalizing the planned contents due to the mass limits still needing to be calculated.

• Research Organization: Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Laboratory (SRNL)
• Sponsoring Organization: USDOE Office of Environmental Management (EM)
• DOE Contract Number: AC09-08SR22470
• OSTI ID: 1542575
• Report Number(s): SRNL-STI--2019-00397
• Country of Publication: United States
• Language: English

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