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HTGR Safety Research Program progress report, July--September 1975

Description: Information on HTGR safety research is presented concerning fission product release under normal and accident conditions, primary coolant impurities, structural investigation, safety instrumentation and control systems, reactor accident analysis, and phenomena modeling and systems analysis. 72 references. (DCC)
Date: January 1975
Creator: Kirk, W. L.
Partner: UNT Libraries Government Documents Department

Scoping Analysis of Source Term and Functional Containment Attenuation Factors

Description: In order to meet future regulatory requirements, the Next Generation Nuclear Plant (NGNP) Project must fully establish and validate the mechanistic modular high temperature gas-cooled reactor (HTGR) source term. This is not possible at this stage in the project, as significant uncertainties in the final design remain unresolved. In the interim, however, there is a need to establish an approximate characterization of the source term. The NGNP team developed a simplified parametric model to establish mechanistic source term estimates for a set of proposed HTGR configurations.
Date: January 1, 2012
Creator: Lowry, Pete
Partner: UNT Libraries Government Documents Department

Characterization of stack effluents from certain nuclear facilities. Final report, April 1, 1972--June 30, 1973

Description: BS>Nuclear power reactors produce copious quantities of several species of permanent gas radioactivity, some directly by fission and others by neutron activation of reactor materials and coolants. The gaseous effluents from a boiling-water reactor (BWR), two pressurized light-water reactors (PWR), a high- temperature gascooled reactor (HTGR) and a pressurized heavy-water research reactor (PHWR) have been analyzed for radioactive and stable constituents. In the case of the BWR, direct stack sampling has insured representative sampling. The PWRs, HTGR, and PHWR do not provide for direct stack sampling, so analyses of hold-up tank gas, pressure-vessel gas, cover gas, primary-coolant strip-gas, and containment air were required to derive characteristic patterns of gas releases from these reactors. Gamma-emitting gaseous species Were measured spectrometrically using a Ge(Li) detector. Chromatographic separation of various gas fractions on a series of molecular sieve columns permitted the use of internal gas-proportional counting tubes for spectrometric resolution of beta- emitting gas species. In addition to measurement of gammaemitting noble gases, / sup 3/H (as a hydrogen gas and methane), /sup 14/C (as methane and carbon dioxide), /sup 37/Ar and /sup 36/Ar have been quantitatively identified. Higher hydrocarbon, carbon monoxide, and methyl iodide fractions in the gaseous effluents contained only very low quantities of radioactivity. Estimases are provided of total annual release of the several species. relative release rates as compared to control requirements, and estimates of long-range transport of / sup 37/Ar as compared to atmospheric measurements performed by other laboratories. (auth)
Date: January 1, 1973
Creator: Matuszek, J.M.; Paperielio, C.J. & Kunz, C.O.
Partner: UNT Libraries Government Documents Department

Analysis of chemical failure of coated UO$sub 2$ and other oxide fuels in the high-temperature gas-cooled reactor

Description: The thermodynamic data for unirradiated dioxides in the U- ThPu-O system are briefly reviewed. Calculations of oxygen release during fission were made and were found to agree qualitatively with experimental measurements. Theories were developed for prediction of mass transport rates in oxide particles; these included control by either CO-- CO/sub 2/ diffusion, reactions such as disproportionation of carbon monoxide, or solid-state diffusion through the kernel. Methods were devised for the determination of the general type of rate- controlling mechanism from the quantitative analysis of inreactor and out-of- reactor experiments. Application of these methods to an in-pile experiment indicated that CO-- CO/sub 2/ diffusion did not control the rate of UO/sub 2/ or (Th,U)O/sub 2/ migration in BISO particles; instead, control by solid-state diffusion was indicated. (54 references) (auth)
Date: January 1, 1974
Creator: Lindemer, T.B. & de Nordwall, H.J.
Partner: UNT Libraries Government Documents Department

Irradiation performance of advanced fuels for HTGR's

Description: From international conference on nuclear fuel performance; London, UK (15 Oct 1973). Fuel for large HTGR power stations in the United States consists of coated particles of ThO/sub 2/ as fertile material mixed with smaller coated particles containing fissile material, either /sup 233/U from recycle of bred fuel or /sup 233/U as makeup fuel. Recycle fuel particles containing /sup 233/U mixed with thorium in sol-- gel oxide microspheres have been prepared and experiments in progress will test a fuel compositon consisting of Th/U = 4 to full exposure and burnup. The use of weak-acid ion exchange resin particles as precursors for either type of fissile fuel kernel offers several advantages.in processing and properties. Pilot-scale preparation and testing of resin-base fuels demonstrated that their performance is adequate and indicate that such fuels may be capable of operating at temperatures well above 1300 deg C. Such high-performance fuels are desirable for process heat and direct-cycle applications. (auth)
Date: January 1, 1973
Creator: Coobs, J.H.; Eatherly, W.P. & Scott, J.L.
Partner: UNT Libraries Government Documents Department

Final report on PCRV thermal cylinder axial tendon failures

Description: The post-test examination of the failed tendons from the PCRV thermal cylinder experiment has been concluded. Failures in the wires are attributed to stress-corrosion cracking. The cause of tendon failures has not been unequivocably established, but they may have been due to nitrates in the duct. The wires employed in the manufacture of the tendons will crack in less than 72 hr in a 0.2 M solution of ammonium nitrate at 70$sup 0$C. The quality of the wires is poor, and surface cracks were detected. These could have acted as concentrating sites for both stress and the deleterious contaminants. It is believed that the factors that led to the failures in the thermal cylinder experiment were unique. An improper formulation of the epoxy resin did not provide the tendon anchor plate seal that was desired; indeed, the improper formulation is responsible for the high level of nitrogen in the ducts of the failed tendons. (auth)
Date: January 1, 1976
Creator: Canonico, D.A.; Griess, J.C. & Robinson, G.C.
Partner: UNT Libraries Government Documents Department