Nuclear fission products

Uranium is converted by CIF, BiF, and BrP to UF. The recovery of uranium from irradiated fuels has been the subject of numerous and extensive investigations sponsored by atomic energy agencies in a number of countries (55—63). The fluorides of the nuclear fission products are nonvolatile hence the volatile UF can be removed by distiUation (see Nuclearreactors Uraniumand uranium compounds). 

The several cases reported of very high yields of nuclear fission products in molecule form clearly involve preservation of bonds formed by -precursors. These and a number of other studies will be discussed in the next section. 

Jensen, K. A., Janeczek, J., Ewing, R. C., Stille, P., Gauthier-Lafaye, F. Salah, S. 2000. Cran-dallites and coffinite retardation of nuclear fission products at the Bangombe nuclear fission reactor. Material Research Society Symposium Proceedings, 608, 525-532. 

Radioactive decay exhibits a first-order rate law, rate = —AN/At = kN, where N denotes the number of radioactive nuclei present at time f. The half-life of stron-tium-90, a dangerous nuclear fission product, is 29 years. 

Rocks, minerals, nuclear fission products, biological material Solvent extraction as MHFA complex optional purification by back-extraction Spectro- photometric 0.0062 mg/L (with back-extraction) 99-103 Abassi 1989... 

In an energy system based on breeder reactors, it is necessary to process the used fuel elements to recover the fertile elements and discard the waste products. The difficulty with this approach lies in the handling of the uranium, plutonium and highly radioactive nuclear fission products. 

The detonation of nitrogen iodide by nuclear fission products was reported by Feenberg [42]. Small samples of nitrogen iodide mixed with uranium oxide (about 0.5 g) were exposed to a 200-mg Ra-Be neutron source surrounded by 6 cm of paraffin. The average exposure required to produce detonation was 40 min, but individual initiations took from 1 min to several hours. Similar results were obtained by Fabry et al. [43]. 

After more than 400 atmospheric nuclear test explosions and the fallout from Chernobyl, Cs became the most frequently released nuclear fission product throughout Central Europe. Cesium behaves like potassium it has a ubiquitous distribution inside the body, especially in soft tissues. In the gastropod Helix pomatia the biological half-time after a single 24-h dietary dose was 2.5 days for the short-lived component and 28.5 days... 

The method of obtaining nuclear fission products which comprises assembling a sufficient volume of a slurry comprising a thermal neutron fissionable material in heavy water to Initiate a self-sustaining nuclear chain reaction, maintaining said reaction for a period of time... 

HLW generally refers to materials requiring permanent isolation from the environment. It frequently arises as a by-product of nuclear power generation (reprocessing streams or spent fuel) or from the isolation of fissile radionuclides from irradiated materials to be used in nuclear weapons production. When nuclear fuel from reactor operations (civilian or defense) is chemically processed, the radioactive wastes include highly concentrated liquid solutions of nuclear fission products. Typically, these waste streams are solidified either in a glass (vitrification) or in another matrix. Both the liquid solutions and the vitrified solids are considered HLW. If the nuclear fuel is not processed, it too, is considered as HLW and must be dispositioned. The path most often proposed is direct, deep geologic isolation. 

Radiolanthanide Usually, a synthetic radioisotope of a lanthanide produced by neutron irradiation of a stable species, although radiolanthanides are also foimd as nuclear fission products and promethium is only known in the form of radioactive species. 

INTRODUCTION TO NUCLEAR Fission Product Poisons Reed Robert Burn December 1988... 

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