A number of organisms have been examined for their ability to produce electron-spin-resonance signals at low temperatures in response to illumination. The efficiency of the response is of the order of not less than 5%, and the wavelength for maximum response is generally slightly on the longer side of the wavelength of maximum absorption, with a minimum appearing at the wavelength of maximum absorption.

The objective of this supplement is to determine the effects of operation with neutral pH water on crud deposition on fuel surfaces. This supplement authorizes testing designed to show the effects of coolant pH on the thickness of the crud layer deposited on fuel elements. The supplement will not require additional reactor down time nor will it introduce any hazards to the reactor.

The effects of core barrier coatings, void spaces, and surface-cleaning techniques on the quality of Zircaloyclad flat-plate UO/sub 2/ fuel elements prepared by gas-pressure bonding were investigated. Techniques were developed for the application of barrier layers of chromium by a vapordeposition process and of crystalline carbon by a pyrolytic process. These coatings, together with a graphite coating previously developed, were evaluated in pressure-bonded fuel elements for their effectiveness in preventing coreto-cladding reaction and for their general production feasibility. Crystalline carbon coatings 15 to 40 mu in. thick and chromium coatings 25 to 40 mu in. thick were determined to be satisfactory. In the stady of the flow of cladding-plate material into void spaces in the picture-frame assembly, it was established that excessive flow, and consequent thinning of the cladding, can be minimized by individually compartmentalizing the cores with Zircaloy ribs. This design resulted in maximum restriction of the effects of a cladding failure in service. Quantitative data on the maximum amount of void space resulting from manufucturing tolerances or from chipped fuel cores that is tolerable in cladding failure in service. Quantitative data on the maximum amount of void space resulting from manufucturing tolerances or from chipped fuel cores that …