Rapid transuranic

The rapid fission of a mass of or another heavy nucleus is the principle of the atomic bomb, the energy liberated being the destructive power. For useful energy the reaction has to be moderated this is done in a reactor where moderators such as water, heavy water, graphite, beryllium, etc., reduce the number of neutrons and slow those present to the most useful energies. The heat produced in a reactor is removed by normal heat-exchange methods. The neutrons in a reactor may be used for the formation of new isotopes, e.g. the transuranic elements, further fissile materials ( °Pu from or of the... 

Neptunium-237 Np-237 has two production routes. The first is rapid /3 decay of U-237 produced by nuclear reactions in the fuel. The second route is /3 decay of Pu-241 to Am-241, which decays losing an a particle to Np-237. This second route will lead to the in-growth of Np-237 in the waste during storage. Np-237 will only be present in waste contaminated with actinides. This is demonstrated by the waste streams that were found to exceed the GQ level. They were IX resin and sludge from BWA and SPF eontents from HPA. Adequate estimates of Np-237 can be made by ratio to Cs-137 determined by FISPIN in the first instance and then refined by taking account of the accumulation and chemistry of other transuranics already measured. At higher concentrations, it can also be measured by y spectrometry of the short-... 

The rapid methods are based on fast removal of the transuranic elements from interfering materials so that they can be electro-deposited as a group, and measured by alpha energy analysis. The procedure involves the following basic steps (Thomas, 1991). 

Thomas, C.W., A rapid procedure for the measurement of the transuranic elements and thorium. IAEA CRM, Vienna. 1991. 

This group of radionuclides is most likely to be of concern in terrestrially produced foods. Biological concentration processes in freshwater and marine systems can result in very rapid transfer and enrichment of specific radionuclides. The radionuclides which enter such systems can in certain cases be rapidly accumulated by plankton and algae. These organisms serve as food for higher trophic levels and thus the radionuclides become concentrated in organisms such as oysters, clams and shrimps. Radionuclides of particular concern in freshwater and marine food chains include Mn, Fe, Fe, Co, Zn, "Zr, Nb, Ru, °"Ru, " " Ag, " Sb, " l, " Cs, "Cs, Ce and some of the transuranic elements. 

Sr increase in deeper samples. This is consistent with our belief that the transuranic nuclides sink more rapidly than Sr and in association with sinking particles (12). 

Table V shows some transuranic radionuclide concentrations found in near shore sediment close to Cape Cod, Mass. The total transuranic content of these shallow sediments agrees well with that predicted as being delivered to the latitude, arguing that the core segment represents part of the period of high 23sp delivery from SNAP 9A fallout. The implication is that all of the delivered transuranic element is rapidly deposited in the sediment in contrast to the "soluble fallout radionuclides.

The feed UF4 for this process must be exceptionally pure since volatile fluorides of lighter elements pass rapidly up to the enriched product collecting point of an enrichment cascade and cause undesirable contamination of the enriched uranium product. Uranium reprocessed after reactor use must be purifled sufficiently well to prevent transuranic elements from passing into the plant. 

---