preceding paper). In the light of the results presented in this paper, the potential of carbon and graphite fibers for use as reinforcement in composite materials designed for structural appli~tion in nuclear reactors is briefly discussed.
138. Irradiation induced changes of the mechanical properties of pyrocarbon coatings deposited from methane
W. W. Delle (K~nforschungsu~~age Ju~~ch GmbH, West Germany). Young's modulus and crushing stress of the outer pyrocarbon layer of coated fuel particles were measured before and after high-fluence and high-temperature irradiationin the Dounreay Fast Reactor (Scotland). The measuring device is described and the results are discussed in terms of fluence, irradiation temperature and pre-irradiation mechanical properties. 139. Dimensional changes induced in poorly crystalline isotropic carbons by radiation J. L. Kaae, D. W. Stevens, and J. C. Bokros (Gulf G enera Atomic Company, San Diego, California). The dimensional changes induced by fast-neutron irradiation of isotropic pyrolytic carbons deposited below 1600ยฐC have been investigated. Irradiation temperatures ranged from 600 to 1300ยฐC and fast neutron fluences extended to 8 X 10zl nvt. The density and dimensional changes are compared with those of more crystalline isotropic carbons.