Eu-155 5.95E-03 5.72E-03 µCi/g Ra-226 < 1.12E-02 <1.37E-02 µCi/g Ra-228 <9.73E-04 <3.29E+00 µCi/g Ac-227 <9.14E-02 <1.02E-03 µCi/g *Activity in reagent blank about the same order of magnitude as in samples because samples were mistakenly analyzed as blanks.

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Extensive radionuclide analyses were performed on a Sludge Batch 7a (SB7a) sample collected from Tank 40. Results of these analyses were used to project the radionuclide content of the SB7a waste over the 1100 year time period from calendar year 2015 to 3115. This was done to determine which radionuclides were reportable per the requirements of the Waste Acceptance Product Specifications (WAPS) and the Defense Waste Processing Facility (DWPF).Twenty-five radionuclides in SB7a waste were identified as being reportable based on the criterion of contributing ≥ 0.01 percent of the total curie content from 2015 to 3115 and having half-lives ≥ 10 years. These twenty-five radionuclides are: Ni-59Ni Three of these radionuclides -Th-229, Cm-246, and Cf-251 -are ones that are absent from the list of radionuclides projected to be reportable in the DWPF glass design basis. In contrast, three of the nuclides identified in the DWPF glass design basis -Pd-107, Cs-135, and Th-230 -are ones not found to be reportable based on the SB7a characterization. These deviations should not be considered unique, as they also occurred in several of the previous sludge batches. However, they demonstrate the importance of utilizing laboratory data to test process expectations.In addition to the twenty-five radionuclides identified above, U-235 and U-236 are also considered reportable -not because of the curie content/half-life criterion -but because of their identification as being always reportable per the requirements of Section 1.6 of the WAPS.Based on the 2015 to 3115 radionuclides projections, the total curie content of the SB7a waste will decrease three orders of magnitude over the upcoming 1100 year time period. Most of this decrease will occur over the first 400 years, due to the dominance of radionuclides with half-lives of 100 years or less. Specifically, Sr-90 (and its short-lived daughter Y-90), Sm-151, and Pu-238 are the primary radionuclides driving the curie content over the first 400 years (2015 to 2415), and each of these radionuclides has a half-life of 100 years or less. In contrast, Pu-239 (and its short-lived daughter U-235m) and Am-241 will dominate the curie content after 2415, once the majority of the Sr-90, Sm-151, and Pu-238 have decayed away. This should not be considered surprising, given the significantly longer half-lives of Pu-239 and Am-241 (24,000 and 430 years, respectively).Three of the reportable radionuclides in SB7a (Sn-126, Pu-242, and Cf-251) were identified based upon minimum detection limits, rather than true detectable concentrations. Methodologies for reducing the minimum detection limits of these particular analytes could be pursued in the future, if more accurate projections are needed. This would improve the ability for making a clear determination of whether or not these radionuclides are reportable.

The Waste Acceptance Product Specifications (WAPS) 1 1.2 require that "The Producer shall report the inventory of radionuclides (in Curies) that have half-lives longer than 10 years and that are, or will be, present in concentrations greater than 0.05 percent of the total inventory for each waste type indexed to the years 2015 and 3115". As part of the strategy to meet WAPS 1.2, the Defense Waste Processing Facility (DWPF) will report for each waste type, all radionuclides (with half-lives greater than 10 years) that have concentrations greater than 0.01 percent of the total inventory from time of production through the 1100 year period from 2015 through 3115. The initial listing of radionuclides to be included is based on the design-basis glass as identified in the Waste Form Compliance Plan (WCP) 2 and Waste Form Qualification Report (WQR) 3. However, it is required that this list be expanded if other radionuclides with half-lives greater than 10 years are identified that may meet the greater than 0.01% criterion for Curie content. Specification 1.6 of the WAPS, International Atomic Energy Agency (IAEA) Safeguards Reporting for High Level Waste (HLW), requires that the ratio by weights of the following uranium and plutonium isotopes be

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