Zirconium nuclides

Hafnium nuclide has a thermal neutron cross section 565 times higher than zirconium nuclide. 

C22-0034. Determine Z, A, and N for each of the following nuclides (a) the nuclide of neon that contains the same number of protons and neutrons (b) the nuclide of lead that contains 1.5 times as many neutrons as protons and (c) the nuclide of zirconium whose neutron-proton ratio is 1.25. 

The presence of uranium in a sample exposed to a flux of thermal neutrons can cause errors if the nuclide or nuclides determined are fission products or are isotopic with them. Hudgens and Dabagian (39) determined zirconium in zirconium-hafnium mixtures by separating the Nb , daughter of Zr formed by n,y reaction, after the addition of carrier. Contributions from fission product niobium (Nb ) can be allowed foi by irradiating a further sample, isolating fission product Ba ° and from the fission yield curve making allowance for radioactive niobium derived from any uranium impurity. 

As a very important topic in contamination buildup, the question is still open to what extent the data on corrosion product solubilities in the primary coolant are of importance for the behavior of trace amounts of cobalt. It seems to be still questionable whether cobalt ferrites as a well-defined compound with properties similar to the nickel ferrites can exist under PWR primary coolant conditions, whether cobalt atoms can be incorporated into a nickel ferrite lattice or whether traces of cobalt may be deposited onto the surfaces of the reactor core by adsorption on other, already deposited oxides. Such adsorption processes may occur even on the Zircaloy oxide films in the absence of any net deposition of corrosion products. Experimental investigations of the interaction of dissolved cobalt with heated Zircaloy surfaces (Lister et al., 1983) indicated that at low crud levels in the coolant cobalt deposition on surfaces is dominated by processes involving dissolved species, with adsorption/desorption processes being the responsible mechanisms. The extent of cobalt deposition is controlled by the type of oxide present on the Zircaloy surface thin black films of zirconium oxide will pick up less cobalt from the solution than thick white oxide films, even when the differences in the available surface areas of both types of oxides are taken into account. The deposition process seems to be little affected by the heat flux in the exposed metal. According to Thornton (1992), such adsorption-desorption exchange processes provide a pathway for radioactive species to be transported around the circuit even when the net movement of corrosion products is minimized this means that under such circumstances the processes of activity transport and of corrosion product transport may be decoupled. They may provide a pathway for target nuclides such as Co to be adsorbed onto fuel rod surfaces even in a core which is virtually free of deposited corrosion product particles. 

From power reactors with no reprocessing, the high-level waste consists of assemblies of zirconium-clad spent fuel rods to be packaged in stainless steel canisters. If the spent fuel is reprocessed, then the high-level waste will be converted to a silicate glass form similar to that from defense operations. The uranium and plutonium content in the waste, and also possibly the strontium-90 and cesium-137, would be reduced by 90 to 99 percent. The nuclides are useful, and their removal reduces the waste disposal problem several ways it reduces the toxicity and heat load of the waste and also reduces the incentive for future... 

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