Neutronics Design and Fuel Cycle Analysis of a High Conversion BWR with Pu-Th Fuel
- Purdue University, West Lafayette, IN 47906-1290 (United States)
- Brookhaven National Laboratory, Upton, New York 11973 (United States)
As part of the U.S. Department of Energy's (DOE) Nuclear Energy Research Initiative (NERI), a 'Generation IV' high conversion Boiling Water Reactor design is being investigated at Purdue University and Brookhaven National Laboratory. One of the primary innovative design features of the core proposed here is the use of Thorium as fertile material. In addition to the advantageous nonproliferation and waste characteristics of thorium fuel cycles, the use of thorium is particularly important in a tight pitch, high conversion lattice in order to insure a negative void coefficient throughout the operating life of the reactor. The principal design objective of a high conversion light water reactor is to substantially increase the conversion ratio (fissile atoms produced per fissile atoms consumed) of the reactor without compromising the safety performance of the plant. Since existing LWRs have a relatively low conversion ratio they require relatively frequent refueling which limits the economic efficiency of the plant. Also, the high volume of spent fuel can pose a burden for waste storage and the accumulation of plutonium in the uranium fuel cycle can become a materials proliferation issue. The development of Fast Breeder Reactors (FBR) as an alternative technology to alleviate some of these concerns has been delayed for various reasons. An intermediate solution has been to examine tight pitch light water reactors which can provide significant improvements in the fuel cycle performance of the existing LWRs by taking advantage of the increased conversion ratios from the harder neutron spectrum in the tight pitch lattice, as well as the by taking advantage of the waste and nonproliferation benefits of the thorium fuel cycle. Several High Conversion BWR designs have been proposed by researchers in Japan and elsewhere during the past several years. One of the more promising HCR designs is the Reduced Moderation Water Reactor (RMWR) proposed by JAERI [1]. Their design was based on a uranium fuel cycle and showed significant improvements in the fuel cycle performance compared to conventional BWRs. However, one of the drawbacks of their design was the potential for a positive void coefficient. In order to insure a negative void coefficient, the JAERI researchers designed a 'flat core' and introduced void tube assemblies in order to enhance neutron leakage in the event of core voiding. The use of thorium in the Purdue/BNL HCBWR design proposed here obviates the need for void tubes and makes it possible to increase the core height and improve neutron economy without the risk of a positive void coefficient. The principal reason for the improvement in the void coefficient is because Th-232 has a smaller fast fission cross section and resonance integral than U-238. In the design proposed here, it is possible to eliminate the void tubes in the RMWR design and replace the axial blanket with active fuel to increase the core height and further improve neutron economy. The core analyses in the work here was performed with the Purdue Fuel Management Code System [2] which is based on the Studsvik/Scandpower lattice physics code HELIOS, and the U.S. NRC core neutronics simulator, PARCS, which is coupled to the thermal-hydraulics code RELAP5. All these codes have been well assessed and benchmarked for analysis of light water reactor systems. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 21167957
- Resource Relation:
- Conference: ICAPP'02: 2002 International congress on advances in nuclear power plants, Hollywood, FL (United States), 9-13 Jun 2002; Other Information: Country of input: France; 7 refs
- Country of Publication:
- United States
- Language:
- English
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