Using Proliferation-Resistant Fuels to Manage Global Plutonium Inventories: Going Beyond the Spent-Fuel Standard

Abstract

The National Academy of Sciences has stated that the growing global stocks of civil and weapons plutonium represent a "clear and present danger." Proliferation-resistant fuels (PRFs) have been proposed by researchers in several countries including France, Italy, Switzerland, Japan and the United States (US) as an effective sink for this plutonium. In place of the UO 2 in mixed uranium-plutonium dioxide (MOX), PRFs blend a nonfertile-oxide-diluant and burnable poisons with PuO 2 . The resultant ceramic is more chemically durable than MOX; consequently, the plutonium cannot be recovered by standard Plutonium-Uranium Reduction Extraction (PUREX) processing and is a more durable waste form than MOX. In the absence of the in situ production of 239 Pu or 233 U found in MOX and thorium fuels, respectively, an extremely deep burn of the plutonium is possible, producing a spent fuel that goes well beyond the spent-fuel standard. Calculations have shown that the reactivity behavior of these fuels can be tailored through the appropriate incorporation of burnable poisons to enable their use in existing lightwater reactors without hardware or operational modifications. Depending on the fuel management strategy employed, PRFs destroy 60-80 wt % of their total plutonium charge, more than twice the consumption possible with MOX fuel. In addition, the isotopics of the residual spent plutonium are >50 wt % 242 Pu, <20 wt % fissile plutonium, and >3 wt % 238 Pu as compared with <15 wt % 242 Pu, >70 wt % fissile plutonium, and <1 wt % 238 Pu for spent MOX. Spent PRF is, therefore, a substantially less attractive source for weapons material than spent MOX. A once-through, one-third PRF core consumes 90 kg of plutonium, whereas a one-third MOX core produces 70 kg. Thus, PRFs can be used to reduce plutonium inventories and the overall proliferation risk posed by commercial fuel cycles. It is recommended that the US Department of Energy develop PRFs on a not-to-interfere basis with the ongoing Material Disposition MOX program. Development of PRFs as a follow on to MOX for burning excess weapons plutonium could be leveraged to promote PRF consumption of global separated civilplutonium stocks. Thus, the US could take an active leadership role to enhance the proliferation resistance of commercial nuclear fuel cycles.