The Radiological and Thermal Characteristics of Fission Waste from a Deep-Burn Fusion-Fission Hybrid (LIFE) and Implications for Repository Performance

Conference · Tue Sep 08 04:00:00 EDT 2009

OSTI ID:967736

Shaw, H F; Blink, J; Farmer, J; Latkowski, J; Kramer, K

We are studying the use of a Laser Inertial-confinement Fusion Engine (LIFE) to drive a hybrid fusion-fission system that can generate electrical power and/or burn nuclear waste. The system uses the neutrons from laser driven ICF to produce tritium and to drive nuclear reactions in a subcritical fission blanket. The fusion neutron source obviates the need for a self-sustaining chain reaction in the fission blanket. Either fissile or fertile could be used as fission fuel, thus eliminating the need for isotopic enrichment. The 'driven' system potentially allows very high levels of burnup to be reached, extracting a large fraction of the available energy in the fission fuel without the need for reprocessing. In this note, we discuss the radionuclide inventory of a depleted uranium (DU) fuel burned to greater than 95% FIMA (Fissions per Initial heavy Metal Atom), the implications for thermal management of the resulting waste, and the implications of this waste for meeting the dose standards for releases from a geological repository for high-level waste. The fission waste discussed here would be that produced by a LIFE hybrid with a 500-MW fusion source. The fusion neutrons are multiplied and moderated by a sequence of concentric shells of materials before encountering the fission fuel, and fission in this region is largely due to thermal neutrons. The fission blanket consists of 40 metric tons (MT) of DU, assumed to be in the form of TRISO-like UOC fuel particles embedded in 2-cm-diameter graphite pebbles. (It is recognized that TRISO-based fuel may not reach the high burnup of the fertile fuel considered here, and other fuel options are being investigated. We postulate the existence of a fuel that can reach >95% FIMA so that the waste disposal implications of high burnup can be assessed.) The engine and plant design considered here would receive one load of fission fuel and produce {approx}2 GWt of power (fusion + fission) over its 50- to 70-year lifetime. Neutron and photon transport calculations were performed using MCNP5. Burnup calculations were performed using a modified version of Monteburns 2.0. The nuclear data used were from ENDF/B-VII. Additional details of the burn calculations can be found in. For comparison to spent fuel from light water reactors (LWRs), we use the projected initial inventory of PWR and BWR fuels (current average age of 23 years since discharge) used for the Yucca Mountain Project Final Environmental Impact Statement. The decay of this initial inventory to 1 million years was calculated using ORIGEN2. The hybrid system considered here would have generated {approx}44 GWe-yr of energy at 99% FIMA. The energy generated per MT is therefore about 1100 MWe-yr/MT. In contrast, using average burnups of 41.2 GWt-day/MT and 33.6 GWt-day/MT for the PWR and BWR fuel slated for disposal at Yucca Mtn., and assuming a thermal electric conversion efficiency of {approx}33%, the total energy generated by the 68,000 MT 'Yucca Mtn. inventory' is {approx}2500 GWe-yr, or {approx}37 MWe-yr/MT, which is {approx}30 times less energy per MT than the waste from the hybrid. Clearly, relative to the current once-through fuel cycle, the use of a deep-burn hybrid to generate electricity would significantly reduce the need for repository capacity.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 967736
• Report Number(s): LLNL-CONF-416698
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
29 ENERGY PLANNING, POLICY, AND ECONOMY
BURNUP
CHAIN REACTIONS
DEPLETED URANIUM
ENVIRONMENTAL IMPACT STATEMENTS
FISSION
FUEL CYCLE
FUEL PARTICLES
HEAVY METALS
HYBRID SYSTEMS
INERTIAL CONFINEMENT
NEUTRON SOURCES
NEUTRONS
NUCLEAR REACTIONS
PHOTON TRANSPORT
RADIOACTIVE WASTES
RADIOISOTOPES
SPENT FUELS
THERMAL NEUTRONS
WASTE DISPOSAL
WASTES
YUCCA MOUNTAIN