This report has been reproduced directly from the best available copy. Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Table 7 Table 8 Table 9 Table A1 ABSTRACTA Depleted Uranium Silicate Container Backfill System (DUSCOBS) is proposed that would use small, isotopicallydepleted uranium silicate glass beads as a backfill material inside storage, tramport, and repository waste packages containing spent nuclear fuel (SNF). The uranium silicate glass beads would fill all void space inside the package including the coolant channels inside SNF assemblies.Based on preliminary analysis, the following benefits have been identified. DUSCOBS improves repository waste package performance by three mechanisms. First, it reduces the radionuclide releases fiom SNF when water enters the waste package by creating a local uranium silicate saturated groundwater environment that suppresses (a) the dissolution andlor transformation of uranium dioxide fuel pellets and, hence, (b) the release of radionuclides incorporated into the SNF pellets. Second, the potential for long-term nuclear criticality is reduced by isotopic exchange of enriched uranium in SNF with the depleted uranium (DV) in the glass. Third, the backfill reduces radiation interactions bemeen SNF and the local environment (package and local geology) and thus reduces generation of hydrogen, acids, and other chemicals ;that degrade the waste package system. In addition, the DUSCOBS improves the integrity of the package by acting as a packing material and ensures criticality control for the package during SNF storage and transport. Finally, DUSCOBS provides a potential method to dispose of significant quantities of excess DU from uranium enrichment plants at potential economic savings. DUSCOBS is a new concept. Consequently, the concept has not been optimized or demonstrated in laboratow experiments. xi EXECUTIVE SUMMARY INTRODUCTIONIt is proposed that small, depleted uranium silicate @US) glass beads be used as a backfill material inside storage, transport, and repository waste packages containing light-water reactor (LW) spent nuclear fuel (SNF). The use of DUS glass beads has the potential to improve repository performance, improve SNF transport and storage, dispose of excess depleted uranium (DU), and reduce system costs. A mechanical description of the Depleted Uranium Silicate Container Backfill System (DUSCOBS) is provided followed by descriptions of how DUSCOBS performs its functions. DUSCOBS is a new concept. This report is a first description of DUSCOBS, its potential advantages, and the associated uncertainties.For the study herein, DUSCOBS was applied to the proposed U.S. Department of Energy (DOE) multipurpose canister (MPC) system. The MPC is an inner container for SNF storage containers, transport casks, and geological disposal packages. DUSCOBS is applicable to (1) alternative MPC designs and (2) other SNF transport, storage, and repository systems. MECHAMCAL DESCRIPTIONThe multipurpose canister (MPC) or waste package would first be loaded w...

This report was prepared as an accoun* o f work sponsored try an agency o* the United Stares Government Neither the United States Government nor any agency thereof, nor any o' tneir emp-ovees makes any warranty, express or implied or assumes a n y iegai liability y responsibility for the accuracy, com pleteness or usefulness of any m'o'mation. apparatus pro-due* v process dis closed or represents fiat its us* would not infringe pnvate'y owned rights Reference herein. *o any spec-f c commeroiai product process or service by trade name t r ademark manufacturer or Dtherwse does no-necessarily consti tute or imply its endorsement recommendation, j' favoring t, tne United States Government or any agency "^'ao*The ..ews an*-; opinions of authors expressed herein dc n ot necessa ri . state v reflect tn,ov; o f *r,e United States Government or any agency therec ORNL/CSD/TM-251

Schematic of a typical Westinghouse fuel rod. 2-13Schematic of a typical Westinghouse fuel assembly* 2-14 Schematic of VANTAGE 5 fuel assembly. 2-15Schematic of a fuel rod from St. Lucie Plant-1 -2-16 14 X 14 array. 2.5Schematic of a fuel assembly from St. Lucie 2-17 Plant-1 -14 X 14 array. 2.6Schematic of a fuel rod from Arkansas Nuclear One, 2-18 Unit 2 -16 X 16 array. 2.7Schematic of a fuel assembly for Arkansas Nuclear (toe, 2-19 Unit-2 -16 X 16 array. 2.8Babcock and Wilcox fuel rod. 2-20 2.9 Babcock and Wilcox fuel assembly. 2-21 2.10 Typical General Electric fuel rod and assembly. 2-22 2.11 Cutaway diagram of an 8 x 8 General Electric fuel 2-23 assembly. 2.12 Cutaway diagram of QUAIH-fuel assembly. 2-24 2.13 Cutaway diagram of a partial QUAIH-fuel ass^nbly 2-25 showing internals. 2.14 Cutaway diagram of QUAIH-fuel channel. 2-26 2.15 Cutaway diagram of a QUAD-t-fuel assembly with 2-27 partially removed minibundle. 2.16Cutaway diagram of a QUAIH-fuel minibundle. 2-28 3.1Radioactivity produced by 1 metric ton of initial 3-7 heavy metal: PWR; 60,000 MWd. 3.2Radioactivity produced by 1 metric ton of initial 3-8 heavy metal: PWR; 33,000 MWd. 3.3Radioactivity produced by 1 metric ton of initial 3-9 heavy metal: BWR; 40,000 MWd. 3.4Radioactivity produced by 1 metric ton of initial 3-10 heavy metal: BWR; 27,500 MWd. C.lData collection pathway for spent fuel characteristics C.2 Calculational pathway for 0RIGEN2-generated data. C.3Construction pathway for the nuclear waste characteristics data base. XI LIST OF TABLES (continued) Table Page 3.17 Variation in neutron production (neutrons/s«MTIHli| ^ 3-40 spontaneous fission as a function of time since discharge from a 60,000-MWd/MTIHM PWR 3.18 Variation in neutron production (neutrons/S'MTIHM) by 3-40 spontaneous fission as a function of time since discharge from a 33,000-MWd/MTIHM PWR 3.19 Variation in neutron production (neutrons/s'MTIHM) by 3-41 spontaneous fission as a function of time since discharge from a 40,000-MWd/MTIHM BWR 3.20 Variation in neutron production (neutrons/s'MTIHM) by 3-41 spontaneous fission as a function of time since discharge from a 27,500-MWd/MTIHM BWR 3.21 Variation in neutron production (neutrons/s'MTIHM) by 3-42 the alpha-neutron reaction as a function of time since discharge from a 60,000-MWd/MTIHM PWR 3.22 Variation in neutron production (neutrons/s'MTIHM) by 3-43 the alpha-neutron reaction as a function of time since . discharge from a 33,000-MWd/MTIHM PWR 3.23 Variation in neutron production (neutrons/s'MTIHM) by 3-44 the alpha-neutron reaction as a function of time since discharge from a 40,000-MWd/MTIHM BWR 3.24 Variation in neutron production (neutrons/s'MTIHM) by 3-45 the alpha-neutron reaction as a function of time since discharge from a 27,500-MWd/MTIHM BWR 3.25 Variation in photon production (photons/s»MTIHM) as a 3-46 function of time since discharge from a 60,000-MWd/MTIHM PWR 3.26 Variation in photon production (photons/s'MTIHM) as a 3-47 function of time since discharge from a 33,000-MWd/MTIHM PWR 3.27 Variation in photon pr...

This report has been reproduced dkectlyfromthe best availablecopy. Because RADAC uses a preselected set of decay times and does not make in-reactor calculations, it should not be viewed as a substitute for ORIGEN2. RADAC is intended for use in applications in which accumulations at the decay times provided by h e code are sufficient for the user's purposes.xiii

No abstract