From March through May, the Center for Nuclear Security Science and Policy Initiatives (NSSPI) welcomed Dr. Masaki Saito as a NSSPI visiting scholar. Dr. Saito is a professor emeritus and the former department head of the Department of Nuclear Engineering at Tokyo Institute of Technology. He is also the former Director of the Academy for Global Nuclear Safety and Security, a program supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology, which offered students a unique educational experience in nuclear safety and security. During his time at Texas A&M University, Dr. Saito collaborated with NSSPI Director Dr. Sunil Chirayath on a research study analyzing the use of multiple recycling in nuclear power reactors to enhance the proliferation resistance of reprocessed uranium (RepU).
While reprocessing is seen as a means of extracting additional energy from used fuel reserves and avoiding waste, commercial spent fuel reprocessing is also considered a proliferation risk, since it transmutes highly radioactive spent fuel into a more desirable form that could be diverted and used for nuclear weapons. Drs. Saito and Chirayath are looking into ways of making this product less desirable, or more proliferation resistant.
According to Dr. Chirayath, “This proliferation resistance enhancement of uranium is possible due to the buildup of non-fissile 236U in the spent fuel since 236U and 235U get coenriched while attempting to produce highly enriched uranium (HEU).” The buildup of 236U in the spent fuel also simultaneously enhances the proliferation resistance of plutonium because 236U gets transmuted to 238Pu, an isotope that is considered undesirable for the manufacture of a nuclear explosive device.
Dr. Saito said, “The ultimate goal of my recent research is to reduce the danger from nuclear weapons politically and scientifically towards ‘Atoms for Peace’ and a world without nuclear weapons.”
As a visiting scholar, he had the opportunity to interact with NSSPI students and faculty. In a NSSPI seminar, he spoke to them of the misery of nuclear weapons, as experienced in Japan through the bombings of Hiroshima and Nagasaki.
“The Bells of Nagasaki,” explained Dr. Saito, “is a book by Dr. Takashi Nagai that vividly describes the indescribable devastation that struck Nagasaki. In the final chapter, it is noteworthy that he draws a distinction between the tendency to emotionally deny the peaceful use of nuclear energy, which is still seen today, and he explains to his son very calmly the possibility of peaceful uses of nuclear energy in the future.” He sees his current research in proliferation resistance as both protective against nuclear weapons production and simultaneously supportive of nuclear energy as a benefit to society.
During Dr. Saito’s time with NSSPI, he and Dr. Chirayath prepared a contribution to the newest revision of the International Atomic Energy Agency (IAEA) Nuclear Energy Series NF-T-4.4 on “Use of Reprocessed Uranium: Challenges and Options,” first published in 2007, titled “Comparison of Predictions of Attainable Maximum Possible Enrichment of 235U of RepU between Simple and Cascade Uranium Enrichment Models.” The IAEA is undertaking the revision of NF-T-4.4 through a series of consultancy and technical meetings to which both Drs. Saito and Chirayath will be contributing in the coming months. A journal article featuring their collaborative work is also forthcoming.