: : 7 : ; : = : : 9 ; 8 : ; / he use of organic liquids as reactor moderator-coolants is presented. A major part of the study was devoted to the mechanism of radiolytic damage to coolants. A mathematical treatment for handling information on the relative reactivity of different positions on an aromatic ring was developed in some detail. Determinations on products from the radiolysis of terphenyls, biphenyl, and mixtures of these with benzene indicate that free radicals may be the main reactive species generated but that others are present. Comparison of the data with reactions of chemically or photochemically generated free radicals shows that the radiolysis is not random, especially at 300 deg C, but that meta radicals are more frequently formed. Attack by the active species on another molecule is favored in the para position and repressed at the ortho position compared to the meta. The distribution of isomers found indicates that H/sub 2/ abstraction by the free radicals and isomerization reactions do not occur to an appreciable extent. New analytical methods were developed. Chromatography on a solid salt column using LiCl proved to be a very satisfactory method for quaterphenyls and most hexaphenyls. …

Thirty-three papers presented at the Thorium Fuel Cycle symposium are given. Topics covered include fuel-cycle technology, raw materials, reactor physics, and reactor concepts. Separate abstracts were prepared for each of the papers. (M.C.G.)

Monoclinic FeSO4·7H2O is the stable solid phase between -1.82° and 56.6° C in contact with a saturated water solution of FeSO4. It occurs in nature as an oxidation product of Fe-containing sulfides an is called melanterite. FeSO4·7H2O belongs to a series of compounds Me2+SO4·nH2O, where Mn2+ is a cation with an approximate ionic radius of 0.7Å. The 1-, 4- and 5-hydrates are known to crystalize each in only one form, whereas the hexa- and the heptahydrates occur both in two different forms. The crystal structure of the tetragonal NiSO4·6H2O; Zalkin, Ruben and Templeton reported the structure of the monoclinic CoSO·6H2O. Of the structure of the heptahydrates but one was described: the orthorhombic form of NiSO4·7H2O. No details were known about one of the monoclinic heptahydrates, though Leonhardt and Ness published the cell constants and the space group of FeSO4·7H2O.. In addition they stated essentially correct positional parameters for the sulfur atom and gave the correct positions of the iron atoms. The present investigation has been undertaken as part of an extensive study of salt hydrates. A preliminary account has been published before.