If offsite power is interrupted, the availability of onsite alternating current power supplies is a major factor in assuring acceptable safety at commercial light-water-cooled nuclear power plants. To control the risk of severe care damage during station blackout accidents at a given plant, the reliability of the emergency diesel generators (EDGS) to start and load-run upon demand must be maintained at a sufficiently high level. The minimum EDG reliability, which we denote by RT, is targeted at either 0.95 or 0.975 per nuclear unit consistent with the reliability level that the plant operator assumed in the coping analysis for station blackout. In 1992 the US Nuclear Regulatory Commission (NRC) considered an amendment that would require licensees to test and monitor EDG reliability against performance-based criteria that indicate possible degradation from the EDG target reliability levels. They originally proposed the following set of fixed sample-size triggers for use in monitoring EDG reliability. The purpose of this report is to compare the performance of the proposed triggers with corresponding alternative sequential variable sample-size triggers which potentially permit earlier detection of EDG reliability degradation without significantly increasing the false alarm rate. The comparison is to be done in a simulated use environment by …

A correlated k-distribution model for the atmospheric transmission of major molecular species has been used to calculate the tropospheric radiative forcing for the ground state, v{sub 3} band of SF{sub 6} and CH{sub 4}. A mid latitude summer, clear sky approximation, temperature-pressure distribution was used in the radiative transfer calculations. For the SF{sub 6} calculations a value of 0.26 W/m{sup 2} was obtained for the v{sub 3} band forcing using a new value of the measured integrated band absorption for SF{sub 6}. The abundance used was 1 ppbv of SF{sub 6}. Hot band contributions to the forcing are estimated to be on the order of three times the value of the v{sub 3} value giving a total radiative forcing of about 0.73 W/m{sup 2}. For the CH{sub 4} calculation a value of 1.71 W/m{sup 2} was obtained and this number agrees with previously published CH{sub 4} radiative forcing values to with four percent. The radiative forcing calculation for SF{sub 6} issued to estimate the global warming potential (GWP) of SF{sub 6} using an approximate model developed to provide reasonably 000 accurate GWPS. The results give GWPs for SF{sub 6} of the order of 12000--25000 (CO{sub 2} = 1). We estimate …

This report summarizes major developments in the last ten years which have greatly expanded the space nuclear reactor power systems technology base. In the SP-100 program, after a competition between liquid-metal, gas-cooled, thermionic, and heat pipe reactors integrated with various combinations of thermoelectric thermionic, Brayton, Rankine, and Stirling energy conversion systems, three concepts:were selected for further evaluation. In 1985, the high-temperature (1,350 K), lithium-cooled reactor with thermoelectric conversion was selected for full scale development. Since then, significant progress has been achieved including the demonstration of a 7-y-life uranium nitride fuel pin. Progress on the lithium-cooled reactor with thermoelectrics has progressed from a concept, through a generic flight system design, to the design, development, and testing of specific components. Meanwhile, the USSR in 1987--88 orbited a new generation of nuclear power systems beyond the, thermoelectric plants on the RORSAT satellites. The US has continued to advance its own thermionic fuel element development, concentrating on a multicell fuel element configuration. Experimental work has demonstrated a single cell operating time of about 1 1/2-y. Technology advances have also been made in the Stirling engine; an advanced engine that operates at 1,050 K is ready for testing. Additional concepts have been studied and experiments …

The Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA) [Public Law (PL) 95-604, 42 United States Code (USC) 7901], hereinafter referred to as the ``Act,`` authorizes the US Department of Energy (DOE) to stabilize and control surface tailings and ground water contamination. To fulfill this mission, the DOE has established two projects under the Uranium Mill Tailings Remedial Action (UMTRA) Project Office. The Ground Water Project was established in April 1991 as a major project and a separate project plan will be prepared for that portion of the mission. This project plan covers the UMTRA Surface Project, a major system acquisition (MSA).

Vanadium tubing obtained from Century Tubes, a custom tubing manufacturer, was studied to determine as-received quality and fabricability. Applications for this tubing involve crimping and sealing operations at Pantex Plant requiring very high levels of leak-tightness (leak rates less than 10{sup {minus}8} atm-cc He/sec). The as-received material had poor OD and ID surface finish and cleanliness that needed to be improved before use in component fabrication. Savannah River Technical Center (SRTC) personnel developed a cleaning procedure to make this tubing acceptable for crimping and sealing operations. After suitably cleaning the tubing, we tested several tube sealing techniques and all showed some degree of success. Pantex Plant personnel are now implementing a tube sealing process very similar to one of the techniques studied, a mechanical crimp followed by seal welding.

We have studied the effect of pulsed plasma discharges on gas mixtures simulating diesel engine exhaust by modeling and by experiment. Our modeling results have shown that the pulsed plasma can convert NO{sub x} to N{sub 2} using the nitrogen itself as a reductant. However, this process is energetically unfavorable for the plasma regime of our measurements. In our experiments we found that addition of hydrocarbons improves substantially the energy efficiency of pulsed plasma NO{sub x} reduction. Real exhaust gas contains some gaseous hydrocarbons and carbon monoxide that may prove sufficient for improving the energy efficiency of the ``right`` pulsed plasma reduction process.

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This report provides a complete description of the analytic and discretized equations for 2D deterministic radiation transport. This computational model has been checked against a wide variety of analytic test problems and found to give excellent results. We make extensive use of the discontinuous finite element method.

Measurements were made of the position of Cu strip patterns on 100 micro thick mylar sheets bonded to G10, in order to study printing of precision cathode strip patterns on thin mylar and then bonding themylar to G10 sheets. Purpose is to explore cheaper, simpler methods for fabricating precision cathodes for cathode strip chambers for the GEM Detector muon system and other high energy physics detector systems at RHIC and CERN.

The electromagnetic decay of the nuclei {sup 152-154-156}Dy is analyzed using microscopic Hartree-Fock calculations at finite temperature. The theoretical collective transition probabilities are implemented in numerical simulations to produce theoretical espectra. Thermal shape fluctuations are also taken into account. The inclusion of these correlation is crucial in order to understand the main features of the collective E2 spectra of these isotopes at different energies. The theoretical calculations suggest a shape change as responsible for the unusual features of the spectrum of the nucleus {sup 154}Dy at high energy.

Three tests were conducted on 2.4 meter by 2.4 meter steel frames infilled with structural clay tile to determine the behavior and capacity when subjected to uniform lateral loads. An air bag was used to apply the out-of-plane loads. The walls were subjected to increasing load-unload cycles until virtual destruction of the infill. Cracking in the mortar joints occurred early in the tests, and then the primary load resisting mechanism was arching of the infilled panel. Typically, vertical arching occurred until failure of the top and bottom course tiles. Following failure of these courses, horizontal arching developed enabling the walls to maintain stability.