The Reduced Enrichment Research and Test Reactor (RERTR) Program was established in 1978 at the Argonne National Laboratory (ANL) by the Department of Energy (DOE), which continues to fund the program and to manage it in coordination with the Department of State (DOS), the Arms Control and Disarmament Agency (ACDA), and the Nuclear Regulatory Commission (NRC). The primary objective of the program is to develop the technology needed to use Low-Enrichment Uranium (LEU) instead of High-Enrichment Uranium (HEU) in research and test reactors, without significant penalties in experiment performance, economics, or safety. Eliminating the continuing need of HEU supplies for research and test reactors has long been an integral part of US nonproliferation policy. This paper reviews the main accomplishments of the program through the years.

This paper summarizes the conversion status of US research and test reactors and estimates uranium densities needed to convert reactors with power levels 21 MW from HEU ({ge} 20% U-235) to LEU (<20% U-235) fuels. Detailed conversion studies for each reactor need to be completed in order to establish the feasibility of using LEU fuels.

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The short- and intermediate-range order as well as atomic dynamics in various phosphate glasses were investigated using neutron diffraction and inelastic scattering. The 3-D network of corner-sharing PO{sub 4} tetrahedra in g-P{sub 2}O{sub 5} is highly unstable and hygroscopic. Depolymerization of the network to chain-like structure and eventually to unconnected PO{sub 4} units by incorporating alkali, alkali-earth or transition-metal modifiers is clearly evident in the structure factor S(Q) in the Q < 4 {angstrom}{sup -1} region. The dynamic response to such structural changes is equally strong: e.g., the broad P-O stretching band extending to 170 meV in g-P{sub 2}O{sub 5} is sharpened and shifted down to {approximately}125 meV in the orthophosphate composition. The correlation between the microscopic structure and physical properties for a series of P-glasses is discussed.

We have obtained charge-changing cross sections and partial cross sections for fragmentation of 1.05 GeV/nucleon Fe projectiles incident on H, C, Al, Cu, and Pb nuclei. The energy region covered by this experiment is critical for an understanding of galactic cosmic ray propagation and space radiation biophysics. Surviving primary beam particles and fragments with charges from 12 to 25 produced within a forward cone of half-angle 61 milliradians were detected using a silicon detector telescope to identify their charge, and the cross sections were calculated after correction of the measured yields for finite target thickness effects. The cross sections are compared to model calculations and to previous measurements. Cross sections for the production of fragments with even-numbered nuclear charges are seen to be enhanced in almost all cases.

Feasibility studies have been performed to convert both the Brookhaven Medical Research Reactor (BMRR) and the High Flux Beam Reactor (HFBR) at the Brookhaven National Laboratory from the use of HEU (93%) fuel to the use of LEU (&lt;20%) fuel. The studies are intended to determine suitable LEU fuels that will provide fuel lifetime and neutron flux performance similar to the current HEU fuels. Both reactors use MTR-type fuel assemblies: the BMRR has 18 fuel plates with 140g {sup 235}U (0.43 gU/cm{sup 3}) and the HFBR has 20 plates, of which 18 are fuel with 351 g {sup 235}U (1.1 gU/cm{sup 3}).

The Urals Electrochemical Integrated Plant (UEIP) is the Russian Federation`s largest uranium enrichment plant and one of three sites in Russia blending high enriched uranium (HEU) into commercial grade low enriched uranium. UEIP is located approximately 70 km north of Yekaterinburg in the closed city of Novouralsk (formerly Sverdlovsk- 44). DOE`s MPC&A program first met with UEIP in June of 1996, however because of some contractual issues the work did not start until September of 1997. The six national laboratories participating in DOE`s Material Protection Control and Accounting program are cooperating with UEIP to enhance the capabilities of the physical protection, access control, and nuclear material control and accounting systems. The MPC&A work at UEIP is expected to be completed during fiscal year 2001.

A study was undertaken at Lawrence Livermore National Laboratory to characterize uranium, 6% niobium ingots produced via electron beam melting, hearth refining and continuous casting and to compare this material with conventional VIM/skull melt/VAR material. Samples of both the ingot and feed material were analyzed for niobium and trace metallic elements, carbon, oxygen and nitrogen. This material was also inspected metallographically and via microprobe analysis.

Inelastic scattering data have been collected at incident neutron energies of 50, 150, 300 and 600 meV for hydrogarnet [Sr{sub 3}Al{sub 2}(O{sub 4}H{sub 4}){sub 3}], a model compound for silicate hydrogarents found in the Earth`s crust and mantle. The vibrational spectrum is characterized by a relatively sharp O-H stretch at {approximately}460 meV, which is consistent with the weak O...H bond ({approximately}2.65 {angstrom}) and other complex features in the 20-100 meV region. The mode assignment for isostructural grosslar and the infrared spectra for hydrogarnet were used as a basis for the intreperation of many of the neutron spectral features.

Objective was to examine the creative process, demonstrated by 5 student participants in a class at the Art Center College of Design in Pasadena CA, from the germ of the creative idea through the final creative product. The students, drawn from classes sponsored by LLNL, were assigned the problem of representing ``big`` science, as practiced at LLNL, in a graphic, artistic, or multimedia product. As a result of this study, it was discovered that the process of creativity with these students was not linear in nature, nor did it strictly follow the traditional creativity 5-step schema of preparation, incubation, insight, evaluation, and elaboration. Of particular interest were several emergent themes of the creative process: spontaneous use of metaphor to describe the Laboratory; a general lack of interest in ``school`` science or mathematics by the American art students; a well developed sense of conscience; and finally, the symbolism inherent in the repeated use of a single artistic element. This use of the circle revealed a continuity of thinking and design perhaps related to the idealistic bias mentioned above.

Following termination of the Advanced Neutron Source (ANS) Project, a program of upgrades to the Department of Energy`s High Flux Isotope Reactor (HFIR) was devised by a team of researchers and reactor operators and has been proposed to the department. HFIR is a multipurpose research reactor, commissioned in 1965, with missions in four nationally important areas: isotope production, especially transuranic isotopes; neutron scattering; neutron activation analysis; and irradiation testing of materials. For neutron scattering, there are two major enhancements and several smaller ones. The first is the installation of a small, hydrogen cold neutron source in one of the four existing beam tubes: because of the high reactor power, and the use of new design concepts developed for ANS, the cold source will be as bright as, or brighter than, the Institute Laue Langevin liquid deuterium vertical cold source, although space limitations mean that there will be far fewer cold beams and instruments at HFIR. This project is underway, and the cold source is expected to come on line following an extended shutdown in 1999 to replace the reactor`s beryllium reflector. The second major change proposed would put five thermal neutron guides at an existing beam port and construct a …

Nanostructured powders of automotive catalytic system CuO0Al{sub 2}O{sub 3}, targeted for nitrogen oxides (NOx) removal under lean-burn engine conditions, were investigated using neutron diffraction and small-angle neutron scattering. The crystal phases, structural transformations and microstructure of 10 mol% Cu-Al{sub 2}O{sub 3} powders are characterized according to the heat-treatment conditions. These properties are correlated with the pore structure and NOx removal efficiency determined by nitrogen adsorption isotherm, electron spin resonance, and temperature programmed reaction measurements. The {gamma}-(Cu, Al){sub 2}O{sub 3} phase and the mass-fractal-like aggregate of particles (size {approx} 26 nm) at annealing temperatures below 900{degrees}C were found to be crucial to the high NOx removal performance. The transformation to bulk crystalline phases of {alpha}-Al{sub 2}O{sub 3} + CuAl{sub 2}O{sub 4} spinel above {approximately}1050{degrees}C corresponds to a drastic drop of Nox removal efficiency. The usefulness of neutron-scattering techniques as well as their complementarity with other traditional methods of catalytic research are discussed.

The Electrochemical Plant (ECP) is the one of the Russian Federation`s four uranium enrichment plants and one of three sites in Russia blending high enriched uranium (HEU) into commercial grade low enriched uranium. ECP is located approximately 200 km east of Krasnoyarsk in the closed city of Zelenogorsk (formerly Krasnoyarsk- 45). DOE`s MPC&A program first met with ECP in September of 1996. The six national laboratories participating in DOE`s Material Protection Control and Accounting program are cooperating with ECP to enhance the capabilities of the physical protection, access control, and nuclear material control and accounting systems. The MPC&A work at ECP is expected to be completed during fiscal year 2001.

A lattice dynamical investigation of zircon (ZrSiO{sub 4}) has been carried out to obtain a microscopic understanding of its thermodynamic properties, as well as to examine possible soft modes that may contribute to the phase transformation to scheelite type under high pressure. We have measured the neutron weighted phonon density of states of zircon from a polycrystalline sample. The neutron spectra reveal one-phonon excitations extending to 1130 cm{sup -1}, with phonon bands centered at 226, 298, 363, 540, 661, 726, 945, and 1081 cm{sup -1}. A quantitative analysis of the neutron results was carried out using a lattice dynamical rigid-ion model. 4 refs., 3 figs.

The structure of NdP{sub 5}O{sub 14} consists of cross-linked double chains of corner-sharing PO{sub 4} tetrahedra extending parallel to the crystallographic a-axis. Each Nd atom is coordinated by 8 oxygen atoms. The NdO{sub 8} polyhedra are isolated from each other and share no common oxygen atoms. High-gain and long-lifetime laser action had been reported in NdP{sub 5}O{sub 14} crystals. The neutron excitation spectra reveal a one-phonon density of states extended to about 180 meV with several distinct P-O stretching bands at high energies. These features reflect the existence of different P-O bond lengths among the terminal and bridging configurations and the associated atomic dynamics. Furthermore, magnetic scattering from Nd ions permitted the determination of the energy-level structure of the crystal-field-split Nd:{sup 4}I{sub 9/2} ground term.

Thermo-mechanical processing of ductile irons is a potential method for enhancing their mechanical properties. A ductile cast iron containing 3.6% C, 2.6% Si and 0.045% Mg was continuously hot-and-warm rolled or one-step press-forged from a temperature in the austenite range (900{degrees}C-1100{degrees}C) to a temperature below the A, temperature. Various amounts of reduction were used (from 60% to more than 90%) followed by a short heat ent at 600`C. The heat ent lead to a structure of fine graphite in a matrix of ferrite and carbides. The hot-and- warm worked materials developed a pearlitic microstructure while the press-forged material developed a spheroidite-like carbide microstructure in the matrix. Cementite-denuded ferrite zones were developed around graphite stringers in the hot-and-warm worked materials, but such zones were absent in the press-forged material. Tensile properties including tensile strength and total elongation were measured along the direction parallel and transverse to the rolling direction and along the direction transverse to the press-forging direction. The tensile ductility and strength both increased with a decrease in the amount of hot-and-warm working. The press- forged materials showed higher strength (645 MPa) than the hot-and-warrn worked materials (575 MPa) when compared at the same ductility level (22% elongation).

The transmittance of curved slabs of cerium doped quartz is reported as a function of wavelength and temperature. The spectral range of measurement is 0.25 to 0.725 {micro}m and temperature varies from 300K to 1270K. The short wavelength cutoff for transmission shifts to longer wavelengths monotonically with temperature at a rate of {approximately}3nm/l 00K. The tmnstnittance data for wavelengths less than 0.36 {micro}m are fit to a classical pole fit model using 8 modes (Oscillators) and the temperature dependence of the modes is given. For wavelengths beyond 0.36 {micro}m the data are fit to an ``Urbach rule.`` The bandgap parameter in the Urbach rule decreases linearly with temperature to 1270K and varies from 3.394eV at 300K to 3,183 eV at 1270K, while the steepness parameter also decreases approximately linearly from 8.51 eV{sup -1} to 5.80 eV{sup -1}. The fits are used to compute the spectral and temperature dependent absorption coefficient.

The Fernald Environmental Management Project is a Department of Energy owned facility that produced high quality uranium metals for military defense. The Fernald mission has changed from one of production to remediation. Remediation is intended to clean up legacy (primary) waste from past practices. Little opportunity is available to reduce the amount of primary waste. However, there is an opportunity to reduce secondary waste generation, primarily through segregation. Two programs which accomplish this are the Controlled Area Trash Segregation Program and the RIMIA Solid Waste Reduction Program. With these two programs now in place at the FEMP, it has been estimated that a 60% reduction has been achieved in unnecessary clean waste being disposed as Low Level Waste at the Nevada Test Site. The cost savings associated with these programs (currently 79,000 cubic feet, $428,000) could easily run into the millions of dollars based on the upcoming restoration activities to be undertaken. The segregation of non-radiological waste in the radiologically Controlled Area not only establishes a firm commitment to send only low-level radioactive waste to the Nevada Test Site, but also results in substantial cost avoidance.

An investigation of the rapid rise time of incoherent x-ray emission from targets heated by an ultra-short pulse (USP) high-intensity optical laser was conducted for use as the x-ray source for inner- shell photo-ionized (ISPI) x ray lasing. Previous studies considered front-side x-ray emission; however, ISPI x-ray lasing requires a filtered x-ray source. Modeling using the hydrodynamics/atomic kinetics code LASNEX of a 40 fs USP driving laser with an intensity of 10 exp(17W/CM2) incident on a flat target of thin Au layered on a Be filter is presented. The filter has a modest influence on the x- ray emission of the Au via conduction cooling but has a large effect on the backside spectrum by removing low energy x rays as the Au emission passes through the filter. The use of such a filtered source is shown to provide the needed x rays to achieve high gain in C at 45A.

A diode-side-pumped ZnSe:Cr{sup 2+} laser was operated with a 75 - Watt peak power 1.65 {micro}m InGaAsP/InP pump array. The laser was configured with a ``single-bounce`` architecture to maximize its round-trip gain. Peak output powers of {approx}0.3 Watt were obtained with a 10% - transmitting output coupler and a lightly-doped crystal. The estimated ``mode fill`` of {approx}0.06 will increase with Cr{sup 2+} concentration, raising the output power and extraction efficiency. With a grating tuner and MgF{sub 2}:Co{sup 2+} laser pumping, the laser tuned throughout the 2134 - 2799 nm range.

We have identified the Cranfill multifluid turbulence model (Cranfill, 1992) as a starting point for development of subgrid models of instability, turbulent and mixing processes. We have differenced the closed system of equations in conservation form, and coded them in the object-oriented hydrodynamics code FLAG, which is to be used as a testbed for such models.

The Waste Isolation Pilot Plant (WIPP) in southeast New Mexico has been studied as a transuranic waste repository for the past 23 years. During this time, an extensive site characterization, design, construction, and experimental program was completed, which provided in depth understanding of the dominant processes that are most likely to influence the containment of radionuclides for 10,000 years. Nearly 1,500 parameters were developed using information gathered from this program and were input to numerical models for WIPP Compliance Certification Application (CCA) Performance Assessment (PA) calculations. The CCA probability models require input parameters that are defined by a statistical distribution. Developing parameters begins with the assignment of an appropriate distribution type, which is dependent on the type, magnitude, and volume of data or information available. Parameter development may require interpretation or statistical analysis of raw data, combining raw data with literature values, scaling laboratory or field data to fit code grid mesh sizes, or other transformations. Documentation of parameter development is designed to answer two questions: What source information was used to develop this parameter? and Why was this particular data set/information used? Therefore, complete documentation requires integrating information from code sponsors, parameter task leaders, performance assessment analysts, and experimental …

The Waste Isolation Pilot Plant (WIPP) in southeast New Mexico has been studied as a transuranic waste repository for the past 23 years. During this time, an extensive site characterization, design, construction, and experimental program was completed, which provided in-depth understanding of the dominant processes that are most likely to influence the containment of radionuclides for 10,000 years. Nearly 1,500 parameters were developed using information gathered from this program; the parameters were input to numerical models for WIPP Compliance Certification Application (CCA) Performance Assessment (PA) calculations. The CCA probabilistic codes frequently require input values that define a statistical distribution for each parameter. Developing parameter distributions begins with the assignment of an appropriate distribution type, which is dependent on the type, magnitude, and volume of data or information available. The development of the parameter distribution values may require interpretation or statistical analysis of raw data, combining raw data with literature values, scaling of lab or field data to fit code grid mesh sizes, or other transformation. Parameter development and documentation of the development process were very complicated, especially for those parameters based on empirical data; they required the integration of information from Sandia National Laboratories (SNL) code sponsors, parameter task leaders …