When I was in my senior year of high school, I visited the Nuclear Science and Engineering department at MIT for six weeks, where I was guided by Emeritus Professor Driscoll and graduate student Bo Feng, to undertake a research project. My research project was to optimize the reactor operating conditions and fuel constituents of a pressurized water reactor to minimize the amount of Am-241 and Np-237 present in the waste. I used computer algorithms CASMO and MCNP to simulate the transmuations of particularly radiotoxic isotopes over the “burnup” life of a fuel element. I also optimized the initial fuel element composition to minimize the amounts of the most radiotoxic isotopes that were produced in the waste.
My final results showed that the amounts of Am-241 and Np-237 in the waste could be minimized by using a mixed oxide fuel (MOX) with U-235 enriched to 0.2%, including recycled transuranic isotopes to make up 12.8% of the fuel assembly. My results also showed that the optimal operating conditions are at 100% coolant/moderator density. By burning this MOX fuel, the net amount of Plutonium in the waste is also reduced by 10%. This means that, by recycling radioactive waste and putting it in new fuel elements, the overall radiotoxicity of the nuclear waste lined up for storage (and ultimately disposal) is less radiotoxic. This, in turn, opens up more possibilities for safer and less expensive storage and disposal options. I think this is very exciting!