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Fusion Science and Technology
What are the key cost drivers for microreactors?
Microreactors upend the traditional economics of nuclear power plants by shifting the paradigm from economies of scale (large reactors) to economies of multiple (mass production). While shrinking power output per unit may increase costs per kilowatt compared to large plants, offsetting gains can be expected from simplified and standardized designs, factory fabrication, inherent safety, lower radionuclide inventories, fast installation, and low financing costs. For instance, the lower power density in a microreactor core leads to a greatly reduced decay heat source, simplifying emergency cooling needs. These design aspects can lead to innovations including substantial simplifications to safety and control needs, minimized human operational requirements, a very compact balance of plant, the ability to fabricate almost every component in a factory, shortened construction time, and less daunting financing.
Mathew W. Swinney, Charles M. Folden III, Ronald J. Ellis, Sunil S. Chirayath
Nuclear Technology | Volume 197 | Number 1 | January 2017 | Pages 1-11
Technical Paper | dx.doi.org/10.13182/NT16-76
Articles are hosted by Taylor and Francis Online.
A terrorist attack using an improvised nuclear device is one of the most serious dangers facing the United States. The work presented here is part of an effort to improve nuclear deterrence by developing a methodology to attribute weapons-grade plutonium to a source reactor by measuring the intrinsic physical characteristics of the interdicted plutonium. In order to demonstrate the developed methodology, plutonium samples were produced from depleted uranium dioxide (DUO2) surrogates irradiated in a fast-neutron environment. In order to replicate the neutron flux in a fast-neutron-spectrum reactor and obtain experimental samples emulating weapons-grade plutonium produced in the blanket of a fast breeder reactor, DUO2 samples were placed in a gadolinium sheath and irradiated in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Previous computational work on this topic identified several fission products that could be used to distinguish between reactor types (fast and thermal reactors), specifically: 137Cs, 134Cs, 154Eu, 125Sb, 144Ce, 85Rb, 147Pm, and 150Sm along with the plutonium isotopes. Simulations of the fast neutron irradiation of the DUO2 fuel surrogates in the HFIR were carried out using the Monte Carlo radiation transport code MCNPX 2.7. Comparisons of the predicted values of plutonium and fission product concentrations to destructive and nondestructive assay measurements of neutron-irradiated DUO2 surrogates are presented here. The agreement between the predictions and gamma spectroscopic measurements in general were within 10% for 134Cs, 137Cs, 154Eu, and 144Ce. Additional experimental results (mass spectroscopy) agreed to within 5% for the following isotopes: 85Rb, 147Pm, 150Sm, 154Eu, 148Nd, 144Ce, and 239Pu. Two indicator isotopes previously suggested to differentiate between the reactor types were ruled out for use in the attribution methodology; 125Sb was ruled out due to the difficulty in accurately predicting its concentration, and 242Pu was ruled out because of its low content in weapons-grade plutonium.