Plutonium Destruction

Addition of a small amount of burnable poison to the central displacer would further reduce void reactivity, increase the plutonium loading per bundle as well as the absolute amount of plutonium destroyed, but would decrease the plutonium destruction efficiency. The plutonium destruction efficiency would be reduced from about 77% to 71%, by poison addition that reduces void reactivity from about 8.6 mk to zero. 

Boczar, P.G., M.J.N. Gagnon, P.S.W. Chan, R.J. Ellis, R.A. Verrall, and A.R. Dastur. 1997. Advanced CANDU systems for plutonium destruction. In Advanced Nuclear Systems Consuming Excess Plutonium, ed. E.R. Merz and C.E. Walter, 163-179. Dordrecht, the Netherlands Kluwer. 

This timescale is fuUy sufficient to start, transition to, and implement a full Pu— Th232 u233 cycle facility not just in Canada, but globally with India and China, who both possess ample thorium reserves, including fuel manufacturing, plutonium destruction, and actinide separations. 

The NAS has requested that only reactor concepts that do not contain any uranium or thorium be examined. Eliminating from the reactor prevents the production of more Pu. Similarly, eliminating thorium from the reactor prevents the production of The main reason for not including fertile nuclides is to preclude the production of additional weapons materials. A plutonium-only based fuel provides the highest plutonium destruction rate. 

Section 2 presents the assumptions and requirements upon which the INEL concept was developed. Section 3 contains an overview of the reactor concept. Section 4 lists the conclusions and recommendations. Most of the technical details and discussions are contained in the appendices. The first task was to examine plutonium destruction rates and isotopics for different neutron spectra, as discussed in Appendix A. This study lead to the adoption of a thermal reactor concept instead of reactors with fast or epithermal neutron spectra. The second task was to study the addition of seed materials for selfprotection from materials diversion. Appendix B illustrates that fission products provide the best. self-protection, and seed materials are not needed for the INEL concept. Various fuel types were investigated and are described in Appendix C. The core neutronics studies presented in Appendix D and thermal-hydraulics studies pre.sented in Appendix E were performed concurrently. An evaluation of potential offsite radiation doses... 

Focus will be on the primary mission of plutonium destruction. No attempt will be made to produce electricity, district heating, or beneficial isotopes. However, the design may be able to satisfy some of these missions. 

This section presents an overview of the INEL concept. This concept is not completely defined because of the short duration of this project. Table 1 lists the design parameters that have been chosen. The ranges indicate the design flexibility for minimizing fuel fabrication costs within acceptable safety limits. The INEL selected a power level of 1,000 MW(t) to achieve an acceptable plutonium destruction rate with a low power density over a large, but reasonably sized core. Although the core has a low power density, the fuel is expected to remain in the reactor for several years to achieve high burnup. A few (three to six) reactors of this power level could bum most of the plutonium in a reasonable time frame (30-40 years). 

Plutonium Destruction. The total heat energy available from the fission of 50 MT of 239pu is approximately 4.2 X 10 joules or... 

Establish a credible list of fuel composition candidates along with candidate cladding materials. Plutonium-destruction performance and safety can be optimized. Burnable poison additions should be considered as an integral part of this study. 

Plutonium Destruction Rates and Isotopics for Different Neutron Spectra... 

Total plutonium destruction as a function of exposure is illustrated in Figure A-10 for the five reactor types considered. The very slight differences observable only at high exposure are not significant. 

Figure A-10. Exposure dependent total plutonium destruction for one metric ton of Pu irradiated in selected reactor spectra.

All five reactor types have comparable total plutonium destruction rates. If the goal is the total destruction of all plutonium isotopes, there is little to distinguish among the five reactor types considered in this assessment. 

Eliminating from the reactor prevents the production of more Pu and accelerates plutonium destruction. A major disadvantage of removing jg, e reduction or elimination of a prompt negative Doppler reactivity coefficient. As the plutonium fuel temperature ri.ses, the plu< tonium fission resonances broaden increasing the core reactivity. Without adequate control, this can lead to even higher fuel temperatures and cause a reactor accident. In addition, the delayed neutron fraction for - Pu (0.0022) is much smaller than that of (0.0069). This also makes a pure plutonium reactor more difficult to control. Removal of eliminates the primary reactivity holddown mechanism in LWRs. 

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