China
Africa
Explore chapters and articles related to this topic
The Other Energy Sources
Published in Anco S. Blazev, Power Generation and the Environment, 2021
The second most used fissile isotope is plutonium-239. It can also fission on absorbing a thermal neutron, with the end product being plutonium-240 (Pu-240). Pu-240 makes up a large proportion of reactor-grade plutonium used today—plutonium recycled from spent fuel that was originally made with enriched natural uranium and then used once in a light water reactor (LWR).
Versatile Test Reactor Conceptual Core Design
Published in Nuclear Science and Engineering, 2022
Each fuel assembly contains 217 fuel rods arranged on a triangular pitch in a hexagonal array within the fuel duct. Spacing is maintained between the fuel pins by a steel wire wrapped around the pins. The fuel rods are encapsulated with HT9 cladding and closed at both ends with a HT9 plug. Each rod contains slugs of ternary metallic fuel with a fuel column height of 80 cm. Sodium inside the fuel rod forms a heat-transfer bond between the fuel column and the cladding. Above the fuel, within the rod there is an 80-cm fission gas plenum initially filled with inert gas. The reference fuel for this phase of the project is a ternary metallic alloy, U-20Pu-10Zr. Reactor-grade plutonium is used alongside enriched uranium with 5 at. % 235U to achieve the desired performance.9 The smeared density (i.e., the areal density of the fuel cross section within the cladding inside diameter in the as-fabricated fuel rod) is 75% of the fabricated fuel material density. The dimensions used are based on the fuel irradiation data accumulated from previous fast reactor programs in the United States and were selected in order to ensure a straightforward fuel qualification process without needing additional irradiation data.10 The main fuel assembly dimensions are provided in Table I.
Postclosure Performance Assessment of a Hypothetical Canadian Deep Geological Repository for Thorium-Containing Advanced Heavy Water Reactor Fuels
Published in Nuclear Technology, 2018
Nicholas Chornoboy, Alexandra Levinsky, Charles Kitson, Blair P. Bromley
Currently under investigation are a number of proposed advanced PT-HWR fuels containing thorium. The proposed fuels range from a conventional 37-element bundle with uranium-based fuels having small amounts of thorium mixed into pellets in the end regions, to 35-element bundles with mixed oxide fuels of thorium dioxide having a small, homogeneously mixed fissile component consisting of either low-enriched uranium (LEU) (5 wt% 235U/U), reactor-grade plutonium (RGPu), or 233U. These sources of fissile isotopes were chosen as they represent either possible options in the short term or long term for incorporating thorium into the PT-HWR fuel cycle. In the immediate future, LEU and RGPu could be obtained from existing enrichment facilities and stockpiles of spent light water reactor fuel, respectively, while in the longer term, 233U could be obtained from spent thorium-based fuels.3–5
Nuclear Forensics Methodology for Reactor-Type Attribution of Chemically Separated Plutonium
Published in Nuclear Technology, 2018
Jeremy M. Osborn, Evans D. Kitcher, Jonathan D. Burns, Charles M. Folden, Sunil S. Chirayath
PHWRs under normal operation will discharge fuel at an average burnup of 7.5 GWd/MTU, which results in reactor-grade plutonium being produced as a byproduct in the used fuel. PHWRs are frequently refueled while in operation, leading to a typical refueling of one fuel channel (eight fuel bundles ~100 kg U) per day. Operating in a nonsafeguarded state, the fuel is susceptible to being discharged at a lower than normal burnup enabling the production and diversion of weapons-grade plutonium outside of civilian energy purposes. PHWR core details, obtained via open literature, were used to develop the fuel bundle model for burnup simulations.7