From meeting on new developments in reactor physics and shieiding calculations; Lake Kiamesha, New York, USA (12 Sep The temperature coefficient of the HTOR is composed of a strong negative Doppler coefficient and a positive moderator coefficient, the net effect being about -10 x 10/sup -5// deg C at operating temperature. the positive moderator coefficient is a result of the absence of significant density coefficients and the nuclear characteristics of U- 233. In addition, selected iission products, principally Xe-135, contribute positive components to the temperature coefficient. Current estimates of the value of the temperature coefficient in the HTGR are presented along with recent experimental data pertinent to the subject. (11 references) (auth)

The purpose of this research was to provide the artificial heart design information necessary for the proper development of an implantable nuclear power supply for the artificial heart. A Kwan-Gett hemispherical artificial heant made of silicone rubber was attached to a mock circulation instrumented with pressure, volume and fiow transducers and measurements made of power input to the artificial heant at various locations, source of power losses and efficiencies of the artificial heart under a variety of pumping conditions, volumetric efficiency, pressure required to move the diaphragm of the artificial heat, required motion of the heant diaphragm and pumping characteristics of the antificial heant. The in vitro measurements have been verified by in vivo experiments in calves. The preliminary design of a pumping chamber for the nuclear powered heart has been completed. (auth)