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The quality of radiation-pasteurized halibut stored at 34°F was evaluated subjectively and objectively over a period of 18 weeks. Results of flavor evaluation and chemical analyses showed that the storage life of halibut irradiated at 0.50, 0.75 and 1.00 megarad was extended more than threefold. Although irradiated samples were consistently rated inferior to unirradiated reference sample by the taste panel, they remained in good condition throughout the 18-week period. No viable, aerobic microorganisms were found. Very little increase in trimethylamine nitrogen, volatile acid number and pH was observed. An increase in free amino nitrogen content was noted on the ninth week up to the twelfth week of storage after which a slight decrease was evident. Pasteurizing radiation was found to induce oxidative rancidity in ground halibut as determined by TBA number and peroxide value. Discoloration of the fish or rusting was observed in all irradiated samples except those treated with 0.005 percent of a commercial mixture of antioxidants, Tenox VI. Oxidative rancidity as measured by TBA number and peroxide value was also markedly inhibited by Tenox VI. Thiodipropionic acid used at the same concentration was found ineffective in preventing rancidity and rusting in the irradiated fish. / Graduation date: 1964

Thesis (Ph. D.)--University of Cincinnati, 1973. / Includes bibliographical references (p. 347-354).

ZrN has been identified as a candidate material for use as an inert matrix fuel host for the transmutation of plutonium and minor actinides. These materials will be subjected to large amounts of different types of radiation within the nuclear reactor core. The types of radiation include fission fragments and alpha-particles amongst others. Recent studies suggest that nanocrystalline material may have a higher radiation tolerance than their polycrystalline and bulk counterparts. Some studies have shown that swift heavy ion irradiation may also significantly modulate hydrogen and helium behaviour in materials. This phenomenon is also of considerable practical interest for inert matrix fuel hosts, since these materials accumulate helium via (n,) reactions and will also be subjected to irradiation by fission fragments. The aim of this investigation is therefore to study the effects of fission fragment and alpha particle irradiation on nanocrystalline ZrN. In an effort to simulate the effects of fission fragments on nanocrystalline zirconium nitride different layers (on a Si substrate) of various thicknesses (0.1, 3, 10 and 20 μm) were irradiated with 167 MeV Xe, 250 MeV Kr and 695 MeV Bi ions to fluences in the range from 31012 to 2.61015 cm-2 for Xe, 1×1013 to 7.06×1013 cm-2 for Kr and 1012 to 1013 cm-2 for Bi. The purpose of this irradiation is to simulate the effects of fission fragments on nanocrystalline ZrN. In order to simulate the effects of alpha particles and the combined effects of alpha particles and fission fragments on nanocrystalline ZrN it was irradiated with 30 keV He to fluences between 1016 and 5×1016 cm-2, 167 MeV Xe to fluences between 5×1013 and 1014 cm-2 and also 695 MeV Bi to a fluence of 1.5×1013 cm-2. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C. The different irradiated layers were subsequently analysed via X-ray diffraction (XRD), μ-Raman, transmission electron microscopy (TEM) and nano indentation hardness testing (NIH) techniques. XRD, TEM, μ-Raman and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation. The microstructure of nanocrystalline ZrN remains unaffected by electronic excitation effects even at a very high stopping power. TEM and SEM results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. Results from He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects, but this is possibly due to the lower fluence of Bi ions. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.