GPHS (General Purpose Heat Source) uranium oxide encapsulations supporting satellite safety tests

Impact testing of general purpose heat sources (GPHSs) and their component GPHS clads is done to benchmark extensive safety calculations quantifying launch safety. Impact testing is done in the Isotope Fuels Impact Tester (IFIT), a large-bore gas gun at Los Alamos National Laboratory. Efforts to conduct an impact test at the extreme low end of the temperature range for launch have highlighted uncertainties in determining the GPHS clad temperature during impact tests. In IFIT impact tests, the GPHS clad temperature is inferred from the temperature of the radiological confinement. Heating tests have been done in the IFIT to determine the fueled clad surface temperature as a function of the surface temperature of the tantalum radiological confinement can. Direct measurement of clad temperatures in the impact configuration are described and the effect of emissivity of the various components indicated. The analytical model used to predict clad temperatures is seen to work well at temperatures above 625°C. Appropriate values of emissivity for use in the model were measured in the experiment. Calculation of the experimental clad impact temperature using the ANSYS thermal transport model is necessary at clad temperatures below 625°C. ANSYS modeling indicates that the clad temperature in a recent low-temperature impact was outside the relevant range for launch safety modeling of GPHS clad behavior.

Nuclear Materials Technology (NMT) Division has initiated a development program to recover and purify plutonium-238 oxide from impure sources. A glove box line has been designed and a process flowsheet developed to perform this task on a large scale. The initial effort has focused on purification of {sup 238}PuO{sub 2} fuel that fails to meet General Purpose Heat Source (GPHS) specifications because of impurities. The notable non-actinide impurities were silicon and phosphorus, but aluminum, chromium, iron and nickel were also near or in excess of limits specified by GPHS fuel powder specifications. Among actinide impurities, uranium is of paramount concern because {sup 234}U is the daughter of {sup 2238}Pu by alpha decay, and is the largest actinide impurity. An aqueous method based on nitric acid was selected for purification of the {sup 238}PuO{sub 2} fuel. All aqueous processing used high purity reagents, and was performed in PTFE apparatus to minimize introduction of new contaminants. Impure {sup 238}PuO{sub 2} was first dissolved in refluxing HNO{sub 3}/HF and then the solution was filtered. The dissolved {sup 238}Pu was adjusted to the trivalent state by an excess of reducing reagents to compensate for radiolytic effects, precipitated as plutonium(III) oxalate, and recovered by filtration. The plutonium(III) oxalate was subsequently calcined to convert the plutonium to the oxide. Decontamination factors for silicon, phosphorus and uranium were excellent. Decontamination factors for aluminum, chromium, iron and nickel were very good. The purity of the {sup 238}PuO{sub 2} recovered from this operation was significantly better than specifications. Efforts continue to develop the capability for efficient, safe, cost-effective, and environmentally acceptable methods to recover and purify {sup 238}PuO{sub 2} fuel in a glovebox environment. Plutonium-238 materials targeted for recovery includes impure oxide and scrap items that are lean in {sup 238}Pu values.

The National Nuclear Security Administration (NNSA) has assigned a continuing role to Los Alamos National Laboratory (LANL) in carrying out NNSA's national security mission. It is imperative that LANL continue this enduring responsibility and that NNSA adequately safeguard LANL capabilities. NNSA has identified the need to restrict vehicular access to certain areas within LANL for the purpose of permanently enhancing the physical security environment at LANL. It has also identified the need to change certain traffic flow patterns for the purpose of enhancing physical safety at LANL. The Proposed Action would include the construction of eastern and western bypass roads around the LANL Technical Area (TA) 3 area and the installation of vehicle access controls and related improvements to enhance security along Pajarito Road and in the LANL core area. This Proposed Action would modify the current roadway network and traffic patterns. It would also result in traversing Areas of Environmental Interest identified in the LANL Habitat Management Plan, demolition of part of an historic structure at Building 3-40, and traversing several potential release sites and part of the Los Alamos County landfill. The No Action Alternative was also considered. Under this alternative NNSA would not construct the eastern or western bypass roads, any access-control stations, or related improvements. Diamond Drive would continue to serve as the primary conduit for most vehicle traffic within the LANL core area regardless of actual trip destinations. The No Action Alternative does not meet NNSA's purpose and need for action. The proposed bypass road corridors traverse both developed and undeveloped areas. Several potential release sites are present. These would either be sampled and remediated in accordance with New Mexico Environment Department requirements before construction or avoided to allow for future remediation. In some cases, contaminant levels may fall below remediation thresholds and the Environmental Restoration Project would set requirements for workers. Structural bridges would be used to span canyons that are Areas of Environmental Interest because they include habitat for threatened and endangered species, or because they are 100-year floodplains or wetlands. Traffic congestion is not expected to increase once construction is completed. The Proposed Action would allow for a flexible approach to vehicle access controls in response to security conditions. Traffic safety within LANL would improve because access control would screen out drivers without a need to be in the LANL TA-3 area or along Pajarito Road. There would be adequate parking for University of California personnel and construction workers. Construction and demolition wastes would be transported to a licensed commercial landfill or recycled for other construction projects at LANL or offsite. Construction for the proposed bypass roads would be expected to produce only temporary and localized air and noise emissions. The Proposed Action would have no effects on visual resources, land use, socioeconomics, or environmental justice. The roadways would be designed to accommodate geologic and soil conditions. The demolition of part of Building 3-40 could have an adverse effect on historic structures since it is eligible for the National Register of Historic Places and, therefore, a treatment plan would be negotiated between NNSA and the State Historic Preservation Office.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Louis D. Schulte, Geraldine M. Purdy, Gordon D. Jarvinen, Kevin Ramsey, Gary L. Silver, Jacob Espinoza, Gary H. Rinehart; Recycle of scrap plutonium-238 oxide fuel to support future radioisotope applications. AIP Conf. Proc. 15 January 1998; 420 (1): 1307–1313. https://doi.org/10.1063/1.54753 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental results from integrating the VCHP with an operating Stirling convertor and describes the methodology used to achieve their successful combined operation.

Lockheed Martin contributions to the Cassini mission included power and propulsion for the spacecraft, the Descent Imager / Spectral Radiometer, DISR instrument for the Huygens Probe, as well as the Titan IVB launch vehicle. Cassini is currently in orbit around Saturn performing its primary science mission, investigating Saturn, its many moons, and its complex and beautiful ring system. The Space Power Programs organization in King of Prussia, Pennsylvania, an offsite of Lockheed Martin Space Systems Company, provided the three General Purpose Heat Source — Radioisotope Thermoelectric Generators (GPHS‐RTGs) used to provide electric power to the spacecraft during its mission to Saturn and its moons. The RTGs were the same design as those used to power the Galileo spacecraft on its mission to Jupiter and its moons, and the ESA Ulysses spacecraft on its mission to explore the Sun. Three RTGS provided 880 Watts of electrical power to the spacecraft at the beginning of mission, shortly after launch, 50% more than the power available for the Galileo mission. Other papers will describe the extensive science instrumentation made possible by the abundance of continuous, reliable, and long‐lived power, unprecedented for a deep space planetary mission. The Cassini Propulsion Module Subsystem is the largest interplanetary propulsion system ever to successfully enter orbit around another planet. The propulsion system was designed to be fully redundant for this critical, 11‐year scientific mission to Saturn. The system was designed, assembled and tested at Lockheed Martin’s Space Exploration Systems Company in Littleton, Colorado, before being delivered to the Jet Propulsion Laboratory, JPL in Pasadena California for integration and testing with the spacecraft. The bi‐propellant system design holds 3,000 kg of Monomethyl Hydrazine, MMH and Nitrogen Tetroxide, NTO and uses 132 kg of High Purity Grade Hydrazine for 3‐axis attitude control and Reaction Wheel Assembly, RWA desaturation.

This paper presents a detailed description of Orbital Science Corporation's (OSC) design of a new support system for the General Purpose Heat Source (GPHS) using the aeroshell's existing indentations for interlocking the heat source modules. The housing and support system were recently fabricated and tested to the Jet Propulsion Laboratory (JPL) draft Advanced Radioisotope Power System (ARPS) test requirements at the the Department of Energy's (DoE) Mound facility in Miamisburg, Ohio, USA. The paper presents the test environments and results. This paper also illustrates some of the latest ARPS system design concepts using this specific support system and housing for future deep space missions.

A shielded storage rack has been installed as part of the Radioisotope Power Systems Facility (RPSF) at the U.S. Department of Energy’s (DOE) Hanford Site in Washington State. The RPSF is designed to replace an existing facility at DOE’s Mound Site near Dayton, Ohio, where General Purpose Heat Source (GPHS) modules are currently assembled and installed into Radioisotope Thermoelectric Generators (RTG). The overall design goal of the RPSF is to increase annual production throughput, while at the same time reducing annual radiation exposure to personnel. The shield rack design successfully achieved this goal for the Module Reduction and Monitoring Facility (MRMF), which processes and stores assembled GPHS modules, prior to their installation into RTGs. The shield rack design is simple and effective, with the result that background radiation levels within Hanford’s MRMF room are calculated at just over three percent of those typically experienced during operation of the existing MRMF at Mound, despite the fact that Hanford’s calculations assume five times the GPHS inventory of that assumed for Mound.

An analysis of coated particles fuel compact-general purpose heat source (CPFC-GPHS)

In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal variable conductance heat pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor by bypassing the heat during stops. In a previous NASA Small Business Innovation Research (SBIR) Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for the Stirling RPS. In 2012, one of these VCHPs was successfully tested at NASA Glenn Research Center with a Stirling convertor as an Advanced Stirling Radioisotope Generator (ASRG) backup cooling system. The prototype; however, was not optimized and did not reflect the final heat rejection path. ACT through further funding has developed a semioptimized prototype with the finalized heat path for testing at Glenn with a Stirling convertor. The semioptimized system features a two-phase radiator and is significantly smaller and lighter than the prior prototype to reflect a higher level of flight readiness. The VCHP is designed to activate and remove heat from the GPHS during stoppage with a small temperature increase from the nominal vapor temperature. This small temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the multilayer insulation (MLI). The VCHP passively allows the Stirling convertor to be turned off multiple times during a mission with potentially unlimited off durations. Having the ability to turn the Stirling off allows for the Stirling to be reset and reduces vibrations on the platform during sensitive measurements or procedures. This paper presents the design of the VCHP and its test results with a Stirling convertor at Glenn. Tests were carried for multiple on and off cycles to demonstrate repeatability. The impacts associated with the addition of the VCHP to the system are also addressed in terms of mass and additional heat losses due to the presence of the VCHP.

Honeybees are effective monitors of environmental pollution. Los Alamos National Laboratory (LANL), in fact, has maintained a network of honeybee colonies within and around LANL for 17 years (1979 through 1995); the objectives for maintaining this honeybee network were to (1) determine the bioavailability of certain radionuclides in the environment with respect to LANL operations (3H, 57Co, 60Co, 1S2Eu, 40K, 7Be, 22Na, 54Mn, 83Rb, 137Cs, 238Pu, 239Pu, 90Sr, 241Am, and totU) and (2) estimate the committed effective dose equivalent (CEDE) and the corresponding risk of excess cancer fatalities (RECF) to people who may consume honey from hives located around the perimeter of the Laboratory (Los Alamos [LA] and White Rock/Pajarito Acres [WR/PA], New Mexico). Based on the 17‐year average, bees from nine out of eleven hives and honey from six out of eleven hives on LANL lands contained 3H that was significantly higher (p <0.05) than background. The highest average concentration of 3H in bees (434 pCi mL−1) collected over the years was from LANL's Technical Area (TA) 54—a low‐level radioactive waste disposal site. Similarity, the highest average concentration of 3H in honey (709 pCi mL−1) was collected from a hive located near three 3H storage ponds at LANL TA‐53. The average concentrations of 3H in bees and honey from background hives was 1.1 pCi mL−1 and 1.6 pCi mL−1, respectively. Although the concentration of 3H in bees and honey from most LANL and perimeter (WR/PA) hives were significantly higher than background, most areas, with the exception of TA‐53 and TA‐54, generally exhibited decreasing 3H concentrations over time. Also, all other radionuclides in honey collected from perimeter hives around LANL were not significantly different from background. Overall, the maximum total net positive CEDE—based on the average concentration plus two std dev of all the radionuclides measured over the years after the subtraction of background‐from consuming 11 Ib of honey collected from LA and WR/PA, was 0.031 mrem y−1 and 0.006 mrem y−1, respectively. The highest CEDE was <0.04% of the International Commission on Radiological Protection permissible dose limit of 100 mrem y−1 from all pathways and corresponds to a RECF of 1.6 × 10−8 (0.016 in a million)—far below the Environmental Protection Agency's guideline of 1 × 10−6 (one in a million).

As part of its initiative to fulfill its responsibilities to provide support for the incorporated County of Los Alamos (the County) as an Atomic Energy Community, while simultaneously fulfilling its obligations to enhance the self-sufficiency of the County under authority of the Atomic Energy Community Act of 1955 and the Defense Authorization Act, the U.S. Department of Energy (DOE) proposes to lease undeveloped land in Los Alamos, New Mexico, to the County for private sector use as a research park. The Proposed Action is intended to accelerate economic development activities within the County by creating regional employment opportunities through offering federal land for private sector lease and use. As a result of the proposed land lease, any government expenditures for providing infrastructure to the property would be somewhat supplemented by tenant purchase of Los Alamos National Laboratory (LANL) expertise in research and development activities. The presence of a research park within LANL boundaries is expected to allow private sector tenants of the park to be able to quickly and efficiently call upon LANL scientific expertise and facility and equipment capabilities as part of their own research operations and LANL research personnel, in turn, would be challenged in areas complementary to their federally funded research. In this way a symbiotic relationship would be enjoyed by both parties while simultaneously promoting economic development for the County through new job opportunities at the Research Park and at LANL, new indirect support opportunities for the community at large, and through payment of the basic building space leases. A ''sliding-scale'' approach (DOE 1993) is the basis for the analysis of effects in this Environmental Assessment (EA). That is, certain aspects of the Proposed Action have a greater potential for creating adverse environmental effects than others; therefore, they are discussed in greater detail in this EA than those aspects of the action that have little potential for effect. The Proposed Action would result in an increase of as many as 1,500 new direct jobs and, as many as 2,565 indirect jobs could be created from the development of a research park. Lease of the tract would not reduce the size of LANL or change its site boundary. However, approximately 30 ac (12 ha) of a 60-ac (24-ha) tract would be changed from an undeveloped to a developed status. Under the No Action Alternative, no transfer or lease of Federal lands would occur. LANL would not have the benefit of its research personnel working on a variety of complementary research efforts beyond their federally funded responsibilities. No new jobs would be created from proposed development activities. Undeveloped lands would remain in their current condition. Two hypothetical accidents were analyzed that evaluated a potential chemical release and radiological doses to the public from hypothetical accidents at the proposed Research Park. Neither accident scenario resulted in potentially serious health effects for workers or the public at the proposed Research Park. The cumulative effects of the Proposed Action as well as reasonably foreseeable related actions could result in potential adverse health effects. Environmental effects would be limited to the loss of a small amount of wildlife habitat. Additional economic development would be expected to occur.

The General-Purpose Heat Source (GPHS), an improved radioisotope heat source, employs a unique thermal insulation material, carbon-bonded carbon fiber (CBCF), to protect the fuel capsule and to help achieve the highest possible specific power. The CBCF insulation is made from chopped rayon fiber about 10 ..mu..m in diameter and 250 ..mu..m long, which is carbonized and bonded with phenolic resin particles. The CBCF shapes, both tubes and plates, are formed in a multiple molding facility by vacuum molding a water slurry of the carbonized chopped-rayon fiber (54 wt %) and phenolic resin (46 wt %). The molded shapes are subsequently dried and cured. Final carbonization of the resin is at 1600/sup 0/C. Machining to close tolerances (+-0.08 mm) is accomplished by conventional tooling and fixturing. The resulting material is an excellent lightweight insulation with a nominal density of 0.2 Mg/m/sup 3/ and a thermal conductivity of 0.24 W(m.K) in vacuum at 2000/sup 0/C. Several attributes that make CBCF superior to other known high-temperature insulation materials for the GPHS application have been identified. It has the excellent attributes of light weight, low thermal conductivity, chemical compatibility, and high-temperature capabilities. The mechanical strength of CBCF insulation is satisfactory for the GPHS application; it has passed vibration tests simulating launch conditions. The basic fabrication technique was refined to eliminate undesirable large pores and cracks often present in materials fabricated by earlier techniques. Also, processing was scaled up to incease the fabrication rate by a factor of 10. The specific properties of the CBCF were tailored by adjusting material and processing variables to obtain the desired results. We report here how work on CBCF characterization and development conducted at ORNL from 1978 through 1980 has contributed to the GPHS program to meet the requirements of both the Galileo and Ulysees Missions.

In the hot dry rock (HDR) concept of extracting geothermal energy, as developed by the Los Alamos Scientific Laboratory (LASL), a manmade geothermal reservoir is created by drilling a deep hole into relatively impermeable hot rocks, creating a large surface area for heat transfer by hydraulic fracturing, then drilling a second hole to intersect the fracture to complete the closed circulation loop. The completion of HDR geothermal wells presents cementing problems that are unique. Current presents cementing problems that are unique. Current well depths are from 10,000 to 14,500 ft (3 to 4.4 km) with bottom hole temperatures up to 525 degrees F (275 degrees C). During investigation and development of the reservoir, water injection flows may lower the temperature of the entire wellbore to 104 degrees F (40 degrees C). As a result, the casing string may be subjected to temperature stress cycles representing differential temperatures of up to 455 degrees F (235 degrees C). Experience has shown that the conventional high-temperature completion cement formulation of Class A or B portland cement, stabilized with 40% silica sand, does not withstand these cyclic stresses, and that rapid deterioration of casing-to-cement and cement-to-formation bonds occurs, which allows significant flow in the resulting microannulus. Investigations and tests (both laboratory and downhole) are being conducted by LASL, and other national and private laboratories, to determine other portland cement formulations, thermal setting cements, and special packer completion techniques which will better withstand the temperature, pressure, and flow requirements of HDR geothermal systems. This paper will describe (a) the performance history of casing cement for the existing EE-1 injection well, (b) the proposed cementing plan for the EE-2 injection well presently being drilled, and (c) the completion system being tested in EE-1 for expanded use in EE-2. Introduction The Los Alamos Scientific Laboratory (LASL) for the past six years has been actively investigating the potential for and problems associated with extracting geothermal energy from hot, but essentially dry, rock at moderate depths. In the Los Alamos concept, a manmade geothermal reservoir is formed by drilling into a region of suitably hot rock and then creating a large fracture, using conventional hydraulic fracturing techniques developed by the oil industry. After forming a circulation loop by drilling a second hole into the top of the fractured region, the heat contained in this reservoir is transported to the surface by circulation of water. The water in the earth loop is maintained as a liquid by pressurization at the surface, increasing both the rate of heat removal from the fractured reservoir and the amount of heat transported up the withdrawal hole. To test this concept, a deep exploratory hole (GT-2) was completed in 1974 to a depth of 9610 ft (2929 m) in the granitic basement rocks of the Jemez Mountains of northern New Mexico at Fenton Hill (Fig. 1). The bottomhole temperature was 388 degrees F (197 degrees C). A near-vertical hydraulic fracture with a radius of about 400 ft (120 m) was created near the bottom of GT-2. Drilling of the second deep hole, Energy Extraction Well No. 1 (or EE-1), to intersect the fracture began in May 1975, about 250 ft (75 m) north of GT-2. It was completed in October at a depth of 10,053 ft (3064 m) and a bottomhole temperature of 400 degrees F (205 degrees C). Below 6240 ft (1957 m), EE-1 was directionally drilled to turn the hole through a 205 degrees spiral to create the underground connection. EE-1 was cased to a depth of 9600 ft (2926 m) with 7-5/8-in. casing and forms the injection well of the underground loop.

The first meeting devoted to cold neutron sources was held at the Los Alamos National Laboratory on March 5--8, 1990. Cosponsored by Los Alamos and Oak Ridge National Laboratories, the meeting was organized as an International Workshop on Cold Neutron Sources and brought together experts in the field of cold-neutron-source design for reactors and spallation sources. Eighty-four people from seven countries attended. Because the meeting was the first of its kind in over forty years, much time was spent acquainting participants with past and planned activities at reactor and spallation facilities worldwide. As a result, the meeting had more of a conference flavor than one of a workshop. The general topics covered at the workshop included: Criteria for cold source design; neutronic predictions and performance; energy deposition and removal; engineering design, fabrication, and operation; material properties; radiation damage; instrumentation; safety; existing cold sources; and future cold sources.