Preliminary Disposal Analysis for Selected Accelerator Production of Tritium Waste Streams

Transcription

1 WSRC-MS Preliminary Disposal Analysis for Selected Accelerator Production of Tritium Waste Streams by M. J. Ades Westinghouse Savannah River Company Savannah River Site Aiken, South Carolina J. L. England A document prepared for 1998 ANS ANNUAL MEETING at Nashville, TN, USA from 6/7/98-6/11/98. DOE Contract No. DE-AC09-89SR18035 This paper was prepared in connection with work done under the above contract number with the U. S. Department of Energy. By acceptance of this paper, the publisher and/or recipient acknowledges the U. S. Government's right to retain a nonexclusive, royalty-free license in and to any copyright covering this paper, along with the right to reproduce and to authorize others to reproduce all or part of the copyrighted paper.

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4 P PRELIMINARY DISPOSAL, ANALYSIS FOR SELECTED ACCELERATOR PRODUCTION OF TRITIUM WASTE STREAMS M. J. Ades and J. L. England Westinghouse Savannah River Company Savannah River Site Men, SC A paper proposed for presentation at the 1998 A N S Annual Meeting Nashville,TN June 7-11,1998 and for publication in the proceedings _ This article was prepared in connection with work done under Contract No. DE-ACO989SR18035 with the U. S.Department of Energy. By acceptance ofthis article, the publisher andor recipient acknowledges the U. S. Government's right to retaia a nonexclusive, royalty-fiee license in and to any copyright covering this article, along with the right to reproduce and to authorize others to reproduce all or part of the copyrighted article.

5 PRELIMRVARY DISPOSAL ANALYSIS FOR SELECTED ACCELERATOR PRODUCTION OF TRITIUM WASTE STREAMS ABSTRACT A preliminary analysis was performed for two selected Accelerator Production of Tritium (APT) generated mixed and low-level waste streams' to determine if - One mixed low-level waste (MLLW) stream that includes the Mixed Waste Lead (MWL) can be disposed of at the Nevada Test Site (NTS)and at the W o r d Site. Provided that this waste is granted exemption &omresource Conservation and Recovery Act (RCRA) requirements, the analysis also determines ifthe waste can be disposed of in.the Low-Level Waste (LLW) Vaults at the Savannah River Site (SRS). This waste stream consists of radioactive lead modules (60%lead, 20% -- alumhum, 20% void) used as neutron sourcesin the APT TargetBlanlcet cavity ~ Vessel. - One low-level radioactive waste (LLW) stream, that includes the Tungsten waste stream (ms) generated by the TungstenNeutron Sourcwnodules (Wh tungsten, 20% stet, 20% void) and used in the Target/Blanlcet cavity vessel, can bedisposedofinthellwvaultsatsrs. The maximum averageradiomlclide cuncentrations of the MWL stream were compared with the Waste A c q t a m e Criteria (WAC) limits of the NTS2 and the W o r d Site3. In addition, the maximum average radionuclide concentrations were compared with the SRS Low-Activity Waste (LAW) and the Intermediate -Level Tritium (ET) Performance Assessment (PA) limits' to determine ifthis waste stream can be disposed of in the LLW f d t y at SRS.

6 The maximum average radionuclide concentrations of the T W S were compared with the SRS LAW and ILT PA limits to determine ifthiswaste stream can be disposed of in the LLW disposal facility at SRS. Table 1 shows the radionuclide concentrations of the APT MLLW stream that e x d the concentrations limits of the NTS, the Hadord Site, and the SRS LAW and ILT PA limits. The results show that: - the APT MWL radionuclide concentrations exceed the NTS limits for C-14, Sr90,and Bi-207. Among these three radionuclides, C-14 is of particular significance since it has a relatively high concentration and a long half-life. - the APT MWL radionuclide concentrationsexceed the W o r d Site limits for twelve radionuclides. Of particular significance are the radionuclides that include C-14, Cl-36, Nb-94, Mo-93, and Eu the APT MWL radionuclide concentrations exceed the SRS LAW PA limits and ILT PA limits for m e n and six radionuclides respectively. Among these radionuclide 3-3, C-14, AI-26, Se-79, T i s, and are particularly significant. Table 2 showsthe radionuclide concentrations of the APT T W S that exceed the SRS LAW and ILT PA knits. The results show that this waste stream concentrations exceed the SRS LAW and ILT PA Wts for nine and seven radionuclides, respectkely. Among these radionuclides H-3C-14, AI-26,Se-79, Tc-99, and 1-129are of particular si@cance. The preliminary disposal analysis results indicate that the radionuklide concentrations of the two selected APT waste streams are not in full compliance with the WAC and the PA radionuclide limitsof the disposal sites considered.

7 In order to dispose of the MWL at the NTS, and the T W S at the SRS ILT vaults, the following options are currently being considered: - Use of process material substitutes. - Update and/or revision of the PA limits. - Engineering improvements to the waste form and packaging, and to the disposal vaults. Although the above analysis provides a valuable insight into the disposal options for the selected APT waste streams, the resuits obtained should be considered prelimiaary. As adequate updates and revisions are made to the APT process and disposal facility PA limits, it is expected that the APT waste streams considered will qualitjl for appropriate onsite and/or offsite disposal....

8 REFERENCES 1. J. L. England, Accelerator Production of Tritium Pollution Prevention Design Assessment 0, WSRC-TR , Rev. 0, September 18, Nevada Test Site Waste Acceptance Criteria, NTS WAC (Rev. 0), September Hanford Site Solid Waste Acceptance Criteria, WHC-EP-MM3-4, November Radiological Performance Assessment for the E-Area Vaults Disposal Facility, WSRC-RP , April 15,1994.

9 Table 1 - Radionuclide Concentrations for the APT Mixed Waste Lead Was@ Stream (BS) Exceeding the Nevada Site, Hanford Site, and SRS (LAW and ILT Vaults) Concentration Limits WAC Concentration Limits (Ci/cm3)

10 - Table 2 Radionuclide Concentrations for the APT Tungsten Waste Stream (815) Exceeding the SRS PA Concentration Limits (CilCm3) ~- I Concentration Radionuclide after 5 yrs. PA Concentration Limits (Cilcm3) (Ref. 4) LAW (Cilcm3) (Ref.1) H-3 C-14 AI-26 w c6-60 Ni-59 se-79 TC Eu ' ~ i oo ILT