Methodologies for Evaluating Security Risk and Safeguards for HEU to LEU conversion of a Miniature Neutron Source Reactor (MNSR) using SCALE and ORIGEN
Date of Award
Doctor of Philosophy
Energy Science and Engineering
Howard L. Hall
G. Ivan Maldonado, Brandon Prins, Lee Riedinger
Rising global opinions on security of vulnerable nuclear materials at research reactor facilities against misuse and acquisition by terrorist or violent groups has led to the implementation of the enrichment reduction program focused at reducing enrichment in fuel from about 90% to less than 20%. This program has provided an extraordinary prospect of improving international security to counter the fears of direct use of HEU materials acquired from these facilities for non-peaceful purposes. Ongoing efforts by the United States Department of Energy (DOE) through the Reduced Enrichment in Test and Research Reactors (RETRR) and the International Atomic Energy Agency (IAEA) supports countries to develop and adapt better technical capabilities targeted towards this program. This research enumerated and compared the amount of weapon-usable materials that the reactor produced in both the HEU and LEU fuel at varying time intervals of operation from a simulated neutronic model of the Nigeria Research Reactor (NIRR-1) developed with SCALE and ORIGEN code. Consequently, result obtained showed that weapon-usable 239Pu balance for LEU fuel compared to HEU increased linearly about 10-fold as the number of days of operation increases. This 239Pu growth was strongly considered for the ongoing conversion of Miniature Neutron Source Reactors (MNSR) as a case study because of the concern that out of the nine licensed prototype MNSR worldwide, four are in China, the origin of the design but the other five are in Ghana, Iran, Nigeria Pakistan and Syria. These five countries have well organized terrorist or violent groups that could potentially acquire nuclear materials or sabotage these facilities to disperse radiological materials which should be a call to more action for more security as well as international safeguards and accounting for nuclear materials. Additionally, based on the outcome of this simulation, as well as the vulnerability assessment carried out that included seeming capabilities of terrorist groups operating near the NIRR-1 facility, security risk and safeguards were evaluated, and suggestions were made on security risk of the increasing quantity of weapon-usable 239Pu isotope.
Dahunsi, Stephen Olumuyiwa, "Methodologies for Evaluating Security Risk and Safeguards for HEU to LEU conversion of a Miniature Neutron Source Reactor (MNSR) using SCALE and ORIGEN. " PhD diss., University of Tennessee, 2018.