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A heatpipe-cooled fast reactor concept has been under development at Los Alamos National Laboratory for the past several years, to be used as a power source for nuclear electric propulsion (NEP) or as a planetary surface power system. The reactor core consists of an array of modules that are held together by a core lateral restraint system. Each module comprises a single heatpipe surrounded by 3-6 clad fuel pins. As part of the design development and performance assessment activities for these reactors, specialized methods and models have been developed to perform thermal and stress analyses of the core modules. The methods have been automated so that trade studies can be readily performed, looking at design options such as module size, heatpipe and clad thickness, use of sleeves to contain the fuel, material type, etc. This paper describes the methods and models that have been developed, and presents thermal and stress analysis results for a Mars surface power system and a NEP power source. [ABSTRACT FROM AUTHOR]

The Heatpipe Power System (HPS) is a near-term, low-cost, space fission power system that has been under development at Los Alamos National Laboratory (LANL) for 5 years. The goal of the HPS project is to devise an attractive space fission system that can be developed quickly and affordably. The primary ways of doing this are by using existing technology and by designing the system for inexpensive testing. If the system can be designed to allow highly prototypic testing with electrical heating, then an exhaustive test program can be carried out inexpensively and quickly and thorough testing of the actual flight unit can be performed—which is a major benefit to reliability. Over the past 4 years, LANL has conducted three HPS proof-of-concept technology demonstrations—each has been highly successful. The Heatpipe-Operated Mars Exploration Reactor (HOMER) is a derivative of the HPS designed especially for producing electricity on the surface of Mars. The key attributes of the HOMER are described in this paper, as well as a 20-kWe point design, system scalability, and the current technology status. [ABSTRACT FROM AUTHOR]

The Low Energy Demonstration Accelerator (LEDA), located at Los Alamos National Laboratory, utilizes a slow wire scanner to measure beam profiles. The beam energy is 6.7 MeV and the peak current is 100 mA. This wire scanner profile measurement is located in the High Energy Beam Transport (HEBT) section of the LEDA beam line. This section of beam line is used to expand the proton beam coming out of the LEDA Radio Frequency Quadrupole (RFQ) prior to impacting the beam-stop. The purpose of the scanner is to provide horizontal and vertical beam profiles. The wires or fibers are a Silicon Carbide (SIC) material, and are attached to an actuator driven by a stepping motor. The actuator drives the fibers through the beam in incremental steps. At each step, the amount of secondary electrons generated by the interactions of the proton beam and the wire are measured. From these incremental measurements the beam profile is constructed. This paper will discuss the operation of the scanner, two of the experiments conducted to understand the capability of the SiC wire to survive and some of the different uses of the beam profile data acquired during the ongoing commissioning of LEDA. [ABSTRACT FROM AUTHOR]

Atlas is a high-energy pulsed-power facility under construction at Los Alamos National Laboratory. When completed in late 2000, Atlas will provide a laboratory environment to perform shock compression experiments in regimes presently unattainable by other methods. The high-energy-density environment on Atlas will be produced by the rapid (~4 μs) implosion of a 20-40 gram, ~4 cm radius, 4 cm length cylindrical aluminum or aluminum/high-Z composite liner, driven by a fast current pulse of ~32 MA from a 24 MJ capacitor bank. Implosion velocities up to 20 km/s are predicted, allowing Hugoniot experiments to ~20 Mbar and quasi-adiabatic compression to several Mbar. However, many issues face us in performing such experiments, including how to diagnose conditions inside the imploding liner, how to correct results for distortions and density gradients created by the cylindrical geometry and magnetic drive, and how to prevent geometric distortions and instabilities from degrading results. In this paper, liner performance is predicted for a shock compression experiment utilizing 1-D MHD simulations, and the effect of gradients in density, pressure, and velocity in the impactor prior to collision are discussed. [ABSTRACT FROM AUTHOR]

Milagrito, a detector sensitive to γ-rays at TeV energies, monitored the northern sky during the period February 1997 through May 1998. With a large field of view and high duty cycle, this instrument was used to perform a search for TeV counterparts to γ-rays bursts. Within the Milagrito field of view 54 γ-ray bursts at keV energies were observed by the Burst And Transient Satellite Experiment (BATSE) aboard the Compton Gamma-Ray Observatory. This paper describes the results of a preliminary analysis to search for TeV emission correlated with BATSE detected bursts. Milagrito detected an excess of events coincident both spatially and temporally with GRB 970417a, with chance probability 2.8×10[sup -5] within the BATSE error radius. No other significant correlations were detected. Since 54 bursts were examined the chance probability of observing an excess with this significance in any of these bursts is 1.5×10[sup -3]. The statistical aspects and physical implications of this result are discussed. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The Los Alamos Neutron Science Center, or LANSCE, is an accelerator-based national user facility for research in basic and applied science. At present LANSCE has two experimental areas primarily using neutrons generated by 800-MeV protons striking tungsten target systems. A third area uses the proton beam for radiography. This paper describes the three LANSCE experimental areas, gives highlights of the past operating period, and discusses plans for the future. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]