Nonproliferation improvements and challenges presented by small modular reactors
Small modular reactors (SMRs) may provide an energy option that will not emit greenhouse gases. From a commercial point-of-view, SMRs will be suitable to serve smaller energy markets with less developed infrastructure, to replace existing old nuclear and coal power plants, and to provide process heat in various industrial applications. In this paper, we examine how SMRs might challenge and improve the existing nonproliferation regime. To motivate our discussion, we first present the opinions gathered from an international group of nuclear experts at an SMR workshop. Next, various aspects of SMR designs such as: fissile material inventory, core-life, refueling, burnup, digital instrumentation and controls, under- ground designs, sealed designs, enrichment, breeders, excess reactivity, fuel element size, coolant opacity, and sea-based nuclear plants are discussed in the context of proliferation concerns. In doing this, we have used publicly available design information about a number of SMR designs (B&W mPower, SVBR-100, KLT-40S, Toshiba 4S, and General Atomics EM 2 ). Finally, a number of recommendations are offered to help alleviate proliferation concerns that may arise due to SMR design features.
Neutronic design study of a small modular IPWR loaded with accident tolerant-fully ceramic micro-encapsulated (AT-FCM) fuel
Abstract Small modular reactors (SMRs) offer a green energy option that will be suitable to serve smaller energy markets with less developed infrastructure. In the present work, a neutronic model of a near term deployable SMR of a natural circulation integral pressurized water reactor (IPWR) design is developed using the TRISO type fuel embedded in SiC matrix. The model development is done using the Monte Carlo Code capable of treating the double heterogeneity in implicit random manner. The Low Enriched Uranium Carbide (LEUC) fuel in TRISO form embedded in SiC matrix and cladded with FeCrAl forms a perfect combination for an accident tolerant fuel for light water reactors due to enhanced capability of fission-product retention of TRISO fuel and lower hydrogen production by FeCrAl at elevated temperature. Length of assembly is altered for reduced active height suitable for SMR application. The depletion analysis is performed for the optimization of fuel enrichment and core loading pattern to achieve a uniform core power distribution. The optimized core is capable of producing 160 MW(th) power with a core life time of more than four EFPYs without refueling or shuffling. The Erbia (Er 2 O 3 ), 80 w/o enriched in 167 Er as an integral fuel burnable absorber (IFBA) in QUADRISO form, shown excellent depletion performance and control of power peaking throughout the life cycle. This study showed that Doppler, moderator temperature and coolant void reactivity coefficients are all negative over the core lifetime. Transuranic production is low, with relatively higher 240 Pu content in the spent fuel. This leads to a highly proliferation resistant discharge fuel. A new design of RCCA loaded with HfB 2 absorber is capable of providing the required shutdown margin in all core conditions. Therefore, the SM-IPWR concept satisfies completely the design criteria and the requirements of an ATF loaded PWR.
Ground Fault Protection for Electric Utility Generating Station Medium Voltage Auxiliary Power Systems
Most generating station designs have medium voltage auxiliary power systems with low resistance grounded neutrals.1 In order to provide even higher reliability, the auxiliary power distribution system configurations supply increasingly redundant process equipment.