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Further Dosimetry Studies at Rhode Island Nuclear Science Center.

Description: The RINSC is a 2 mega-watt, light water and graphite moderated and cooled reactor that has a graphite thermal column built as a user facility for sample irradiation. Over the past decade, after the reactor conversion from a highly-enriched uranium core to a low-enriched one, flux and dose measurements and calculations had been performed in the thermal column to update the ex-core parameters and to predict the effect from in-core fuel burn-up and rearrangement. The most recent data from measurements and calculations that have been made at the RINSC thermal column since October of 2005 are reported.
Date: May 5, 2008
Creator: Reciniello,R.N.; Holden, N.E.; Hu, J.-P.; Johnson, D.G.; Meddleton, M. & Tehan, T.N.
Partner: UNT Libraries Government Documents Department

Method for fabricating {sup 99}Mo production targets using low enriched uranium, {sup 99}Mo production targets comprising low enriched uranium

Description: A radioisotope production target and a method for fabricating a radioisotope production target is provided, wherein the target comprises an inner cylinder, a foil of fissionable material (low enriched U) circumferentially contacting the outer surface of the inner cylinder, and an outer hollow cylinder adapted to receive the substantially foil-covered inner cylinder and compress tightly against the foil to provide good mechanical contact therewith. The method for fabricating a primary target for the production of fission products comprises preparing a first substrate to receive a foil of fissionable material so as to allow for later removal of the foil from the first substrate, preparing a second substrate to receive the foil so as to allow for later removal of the foil from the second substrate; attaching the first substrate to the second substrate such that the foil is sandwiched between the first substrate and second substrate to prevent foil exposure to ambient atmosphere, and compressing the exposed surfaces of the first and second substrate to assure snug mechanical contact between the foil, the first substrate and the second substrate.
Date: December 31, 1993
Creator: Wiencek, T.C.; Matos, J.E. & Hofman, G.L.
Partner: UNT Libraries Government Documents Department

Conversion and Blending Facility highly enriched uranium to low enriched uranium as metal. Revision 1

Description: The mission of this Conversion and Blending Facility (CBF) will be to blend surplus HEU metal and alloy with depleted uranium metal to produce an LEU product. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. The blended LEU will be produced as a waste suitable for storage or disposal.
Date: July 5, 1995
Partner: UNT Libraries Government Documents Department

Conversion and Blending Facility highly enriched uranium to low enriched uranium as uranyl nitrate hexahydrate. Revision 1

Description: This Conversion and Blending Facility (CBF) will have two missions: (1) convert HEU materials to pure HEU uranyl nitrate (UNH) and (2) blend pure HEU UNH with depleted and natural UNH to produce HEU UNH crystals. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. To the extent practical, the chemical and isotopic concentrations of blended LEU product will be held within the specifications required for LWR fuel. Such blended LEU product will be offered to the United States Enrichment Corporation (USEC) to be sold as feed material to the commercial nuclear industry. Otherwise, blended LEU Will be produced as a waste suitable for storage or disposal.
Date: July 5, 1995
Partner: UNT Libraries Government Documents Department

Transient analysis for the tajoura critical facility with IRT-2M HEU fuel and IRT-4M leu fuel : ANL independent verification results.

Description: Calculations have been performed for postulated transients in the Critical Facility at the Tajoura Nuclear Research Center (TNRC) in Libya. These calculations have been performed at the request of staff of the Renewable Energy and Water Desalinization Research Center (REWDRC) who are performing similar calculations. The transients considered were established during a working meeting between ANL and REWDRC staff on October 1-2, 2005 and subsequent email correspondence. Calculations were performed for the current high-enriched uranium (HEU) core and the proposed low-enriched uranium (LEU) core. These calculations have been performed independently from those being performed by REWDRC and serve as one step in the verification process.
Date: December 2, 2005
Creator: Garner, P. L. & Hanan, N. A.
Partner: UNT Libraries Government Documents Department

LEU conversion status of US research reactors, September 1996

Description: This paper summarizes the conversion status of research and test reactors in the United States from the use of fuels containing highly- enriched uranium (HEU, greater than or equal to 20%) to the use of fuels containing low-enriched uranium (LEU, < 20%). Estimates of the uranium densities required for conversion are made for reactors with power levels greater than or equal to 1 MW that are not currently involved in the LEU conversion process.
Date: October 7, 1996
Creator: Matos, J.E.
Partner: UNT Libraries Government Documents Department

Low enrichment fuel conversion for Iowa State University. Final report

Description: The UTR-10 research and teaching reactor at Iowa State University (ISU) has been converted from high-enriched fuel (HEU) to low- enriched fuel (LEU) under Grant No. DE-FG702-87ER75360 from the Department of Energy (DOE). The original contract period was August 1, 1987 to July 31, 1989. The contract was extended to February 28, 1991 without additional funding. Because of delays in receiving the LEU fuel and the requirement for disassembly of the HEU assemblies, the contract was renewed first through May 31, 1992, then through May 31, 1993 with additional funding, and then again through July 31, 1994 with no additional funding. In mid-August the BMI cask was delivered to Iowa State. Preparations are underway to ship the HEU fuel when NRC license amendments for the cask are approved.
Date: October 17, 1996
Creator: Bullen, D.B. & Wendt, S.E.
Partner: UNT Libraries Government Documents Department

Development and processing of LEU targets for {sup 99}Mo production

Description: Substituting LEU for HEU in targets for producing fission-product {sup 99}Mo requires changes in target design and chemical processing. We have made significant progress in developing targets and chemical processes for this purpose. Target development was concentrated on a U- metal foil target as a replacement for the coated-UO{sub 2} Cintichem- type target. Although the first designs were not successful because of ion mixing-induced bonding of the U foil to the target tubes, recent irradiations of modified targets have proven successful. It was shown that only minor modifications of the Cintichem chemical process are required for the U-metal foil targets. A demonstration using prototypically irradiated targets is anticipated by the end of 1996. Progress was also made in basic dissolution of both U-metal foil and Al-clad U{sub 3}Si{sub 2} dispersion fuel targets, and work in this area is also continuing.
Date: February 1, 1997
Creator: Snelgrove, J.L.; Vandergrift, G.F. & Hofman, G.L.
Partner: UNT Libraries Government Documents Department

Processing of LEU targets for {sup 99}Mo production: Dissolution of U{sub 3}Si{sub 2} targets by alkaline hydrogen peroxide

Description: Low-enriched uranium silicide targets designed to recover fission product {sup 99}Mo were dissolved in alkaline hydrogen peroxide (H{sub 2}O{sub 2} plus NaOH) at about 90C. Sintering of matrix aluminum powder during irradiation and heat treatment retarded aluminum dissolution and prevented silicide particle dispersion. Gas evolved during dissolution is suspected to adhere to particles and block hydroxide ion contact with aluminum. Reduction of base concentrations from 5M to O.lM NaOH yielded similar silicide dissolution and peroxide destruction rates, simplifying later processing. Future work in particle dispersion enhancement, {sup 99}Mo separation, and waste disposal is also discussed.
Date: September 1, 1995
Creator: Buchholz, B.A. & Vandegrift, G.F.
Partner: UNT Libraries Government Documents Department

Analyses for conversion of the Georgia Tech Research Reactor from HEU to LEU fuel

Description: This document presents information concerning: analyses for conversion of the Georgia Tech Research Reactor from HEU to LEU; changes to technical specifications mandated by the conversion of the GTRR to low enrichment fuel; changes in the Safety Analysis Report mandated by the conversion of the GTRR to low enrichment fuel; and copies of all changed pages of the SAR and the technical specifications.
Date: September 1, 1992
Creator: Matos, J.E.; Mo, S.C. & Woodruff, W.L.
Partner: UNT Libraries Government Documents Department

Progress in dissolving modified LEU Cintichem targets

Description: A process is under development to use low-enriched uranium (LEU) metal targets for production of {sup 99}Mo. The first step is to dissolve the irradiated foil. In past work, this has been done by heating a closed (sealed) vessel containing the foil and a solution of nitric and sulfuric acids. In this work, the authors have demonstrated that (1) the dissolver solution can contain nitric acid alone, (2) uranium dioxide is also dissolved by nitric acid alone, and (3) barrier metals of Cu, Fe, or Ni on the U foil are also dissolved by nitric acid. Changes to the dissolver design and operation needed to accommodate the uranium foil are discussed, including (1) simple operations that are easy to do in a remote-maintenance facility, (2) heat removal from the irradiated LEU foil, and (3) cold trap operation with high dissolver pressures.
Date: December 31, 1996
Creator: Leonard, R.A.; Chen, L.; Mertz, C.J. & Vandegrift, G.F.
Partner: UNT Libraries Government Documents Department

Development and processing of LEU targets for {sup 99}Mo production

Description: Most of the world`s supply of {sup 99m}Tc for medical purposes is currently produced from the decay of {sup 99}Mo derived from the fissioning of high-enriched uranium (HEU). Substantial progress has been made in developing targets and chemical processes for producing {sup 99}Mo using low-enriched uranium (LEU). Target development has been focused on a uranium-metal foil target as a replacement for the coated-UO{sub 2} Cintichem-type target. Although the first designs were not successful because of ion mixing-induced bonding of the uranium foil to the target tubes, recent irradiations of modified targets have proven successful. Only minor modifications of the Cintichem chemical process are required for the uranium-metal foil targets. A demonstration using prototypically irradiated targets is anticipated in February 1997. Progress has also been made in basic dissolution of both uranium-metal foil and aluminum-clad U{sub 3}Si{sub 2} dispersion fuel targets.
Date: April 1, 1997
Creator: Snelgrove, J.L.; Vandegrift, G.F. & Hofman, G.L.
Partner: UNT Libraries Government Documents Department

Progress in chemical treatment of LEU targets by the modified Cintichem process

Description: Presented here are recent experimental results on tests of a modified Cintichem process for producing {sup 99}Mo from low enriched uranium (LEU). Studies were focused in three areas: (1) testing the effects on {sup 99}Mo recovery and purity of dissolving LEU foil in nitric acid alone, rather than in the sulfuric/nitric acid mixture currently used, (2) measuring decontamination factors for radionuclide impurities in each purification step, and (3) testing the effects on processing of adding barrier materials to the LEU metal-foil target. The experimental results show that switching from dissolving the target in the sulfuric/nitric mixture to using nitric acid alone should cause no significant difference in {sup 99}Mo product yield or purity. Further, the results show that overall decontamination factors for gamma emitters in the LEU-target processing are high enough to meet the purity requirements for the {sup 99}Mo product. The results also show that the selected barrier materials, Cu, Fe, and Ni, do not interfere with {sup 99}Mo recovery and can be removed during chemical processing of the LEU target.
Date: December 31, 1996
Creator: Wu, D.; Landsberger, S. & Vandegrift, G.F.
Partner: UNT Libraries Government Documents Department

Development of very high-density low-enriched uranium fuels

Description: The RERTR program has recently begun an aggressive effort to develop dispersion fuels for research and test reactors with uranium densities of 8 to 9 g U/cm{sup 3}, based on the use of {gamma}-stabilized uranium alloys. Fabrication development teams and facilities are being put into place and preparations for the first irradiation test are in progress. The first screening irradiations are expected to begin in late April 1997 and first results should be available by end of 1997. Discussions with potential international partners in fabrication development and irradiation testing have begun.
Date: February 1, 1997
Creator: Snelgrove, J.L.; Hofman, G.L.; Trybus, C.L. & Wiencek, T.C.
Partner: UNT Libraries Government Documents Department

HEU to LEU Conversion and Blending Facility: UF{sub 6} blending alternative to produce LEU UF{sub 6} for commercial use

Description: US DOE is examining options for disposing of surplus weapons-usable fissile materials and storage of all weapons-usable fissile materials; the nuclear material will be converted to a form more proliferation- resistant than the original form. Examining options for increasing the proliferation resistance of highly enriched uranium (HEU) is part of this effort. Five technologies for blending HEU will be assessed; blending as UF{sub 6} to produce a UF{sub 6} product for commercial use is one of them. This document provides data to be used in the environmental impact analysis for the UF{sub 6} blending HEU disposition option. Resource needs, employment needs, waste and emissions from plant, hazards, accident scenarios, and intersite transportation are discussed.
Date: September 1, 1995
Partner: UNT Libraries Government Documents Department

U.S. transparency monitoring of HEU oxide conversion and blending to LEU hexafluoride at three Russian blending plants

Description: The down-blending of Russian highly enriched uranium (HEU) takes place at three Russian gaseous centrifuge enrichment plants. The fluorination of HEU oxide and down-blending of HEU hexafluoride began in 1994, and shipments of low enriched uranium (LEU) hexafluoride product to the United States Enrichment Corporation (USEC) began in 1995 US transparency monitoring under the HEU Purchase Agreement began in 1996 and includes a permanent monitoring presence US transparency monitoring at these facilities is intended to provide confidence that HEU is received and down-blended to LEU for shipment to USEC The monitoring begins with observation of the receipt of HEU oxide shipments, including confirmation of enrichment using US nondestructive assay equipment The feeding of HEU oxide to the fluorination process and the withdrawal of HEU hexafluoride are monitored Monitoring is also conducted where the blending takes place and where shipping cylinders are filled with LEU product. A series of process and material accountancy documents are provided to US monitors.
Date: July 27, 1998
Creator: Leich, D.
Partner: UNT Libraries Government Documents Department

Low-enriched uranium holdup measurements in Kazakhstan

Description: Quantification of the residual nuclear material remaining in process equipment has long been a challenge to those who work with nuclear material accounting systems. Fortunately, nuclear material has spontaneous radiation emissions that can be measured. If gamma-ray measurements can be made, it is easy to determine what isotope a deposit contains. Unfortunately, it can be quite difficult to relate this measured signal to an estimate of the mass of the nuclear deposit. Typically, the measurement expert must work with incomplete or inadequate information to determine a quantitative result. Simplified analysis models, the distribution of the nuclear material, any intervening attenuation, background(s), and the source-to-detector distance(s) can have significant impacts on the quantitative result. This presentation discusses the application of a generalized-geometry holdup model to the low-enriched uranium fuel pellet fabrication plant in Ust-Kamenogorsk, Kazakhstan. Preliminary results will be presented. Software tools have been developed to assist the facility operators in performing and documenting the measurements. Operator feedback has been used to improve the user interfaces.
Date: December 31, 1998
Creator: Barham, M.A.; Ceo, R.N. & Smith, S.E.
Partner: UNT Libraries Government Documents Department

Conversion and Blending Facility highly enriched uranium to low enriched uranium as oxide. Revision 1

Description: This Conversion and Blending Facility (CBF) will have two missions: (1) convert HEU materials into pure HEU oxide and (2) blend the pure HEU oxide with depleted and natural uranium oxide to produce an LWR grade LEU product. The primary emphasis of this blending operation will be to destroy the weapons capability of large, surplus stockpiles of HEU. The blended LEU product can only be made weapons capable again by the uranium enrichment process. To the extent practical, the chemical and isotopic concentrations of blended LEU product will be held within the specifications required for LWR fuel. Such blended LEU product will be offered to the United States Enrichment Corporation (USEC) to be sold as feed material to the commercial nuclear industry. Otherwise, blended LEU will be produced as a waste suitable for storage or disposal.
Date: July 5, 1995
Partner: UNT Libraries Government Documents Department

The LEU conversion status of U.S. Research Reactors.

Description: 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 (&lt;20% U-235) fuels. Detailed conversion studies for each reactor need to be completed in order to establish the feasibility of using LEU fuels.
Date: November 14, 1997
Creator: Matos, J. E.
Partner: UNT Libraries Government Documents Department

OPTIMIZATION OF WATER TO FUEL RATIOS IN CLADDED CYLINDER ARRAYS

Description: Often in criticality safety problems, the analyst is concerned about two conditions: Loss of Mass Control and Loss of Moderation Control. Determining and modeling the maximum amount of fuel that can fit in a given container is usually trivial. Determining and modeling the maximum amount of water (or other potential moderator) is usually more difficult. Optimization of the pitch has been shown to provide an increase in system reactivity. Both MOX and LEU systems have been shown to be sensitive to moderator intrusion in varying pitched configurations. The analysis will have to determine the effect of optimizing the pitch for each array.
Date: March 14, 2007
Creator: Huffer, J
Partner: UNT Libraries Government Documents Department

YALINA-booster subcritical assembly pulsed-neutron experiments : data processing and spatial corrections.

Description: The YALINA-Booster experiments and analyses are part of the collaboration between Argonne National Laboratory of USA and the Joint Institute for Power & Nuclear Research - SOSNY of Belarus for studying the physics of accelerator driven systems for nuclear energy applications using low enriched uranium. The YALINA-Booster subcritical assembly is utilized for studying the kinetics of accelerator driven systems with its highly intensive D-T or D-D pulsed neutron source. In particular, the pulsed neutron methods are used to determine the reactivity of the subcritical system. This report examines the pulsed-neutron experiments performed in the YALINA-Booster facility with different configurations for the subcritical assembly. The 1141 configuration with 90% U-235 fuel and the 1185 configuration with 36% or 21% U-235 fuel are examined. The Sjoestrand area-ratio method is utilized to determine the reactivities of the different configurations. The linear regression method is applied to obtain the prompt neutron decay constants from the pulsed-neutron experimental data. The reactivity values obtained from the experimental data are shown to be dependent on the detector locations inside the subcritical assembly and the types of detector used for the measurements. In this report, Bell's spatial correction factors are calculated based on a Monte Carlo model to remove the detector dependences. The large differences between the reactivity values given by the detectors in the fast neutron zone of the YALINA-Booster are reduced after applying the spatial corrections. In addition, the estimated reactivity values after the spatial corrections are much less spatially dependent.
Date: October 11, 2010
Creator: Cao, Y.; Gohar, Y. & Division, Nuclear Engineering
Partner: UNT Libraries Government Documents Department

The RERTR Program : a status report.

Description: This paper describes the progress achieved by the Reduced Enrichment for Research and Test Reactors (RERTR) Program in collaboration with its many international partners since its inception in 1978. A brief summary of the results that the program had attained by the end of 1997 is followed by a detailed review of the major events, findings, and activities that took place in 1998. The past year was characterized by exceptionally important accomplishments and events for the RERTR program. Four additional shipments of spent fuel from foreign research reactors were accepted by the U.S. Altogether, 2,231 spent fuel assemblies from foreign research reactors have been received by the U.S. under the acceptance policy. Fuel development activities began to yield solid results. Irradiations of the first two batches of microplates were completed. Preliminary postirradiation examinations of these microplates indicate excellent irradiation behavior of some of the fuel materials that were tested. These materials hold the promise of achieving the pro am goal of developing LEU research reactor fuels with uranium density in the 8-9 g /cm{sup 3} range. Progress was made in the Russian RERTR program, which aims to develop and demonstrate the technical means needed to convert Russian-supplied research reactors to LEU fuels. Feasibility studies for converting to LEU fuel four Russian-designed research reactors (IR-8 in Russia, Budapest research reactor in Hungary, MARIA in Poland, and WWR-SM in Uzbekistan) were completed. A new program activity began to study the feasibility of converting three Russian plutonium production reactors to the use of low-enriched U0{sub 2}-Al dispersion fuel, so that they can continue to produce heat and electricity without producing significant amounts of plutonium. The study of an alternative LEU core for the FRM-II design has been extended to address, with favorable results, the transient performance of the core under hypothetical accident conditions. ...
Date: October 19, 1998
Creator: Travelli, A.
Partner: UNT Libraries Government Documents Department

Acceptable standard format and content for the fundamental nuclear material control (FNMC) plan required for low-enriched uranium facilities. Revision 2

Description: This report documents a standard format suggested by the NRC for use in preparing fundamental nuclear material control (FNMC) plans as required by the Low Enriched Uranium Reform Amendments (10CFR 74.31). This report also describes the necessary contents of a comprehensive plan and provides example acceptance criteria which are intended to communicate acceptable means of achieving the performance capabilities of the Reform Amendments. By using the suggested format, the licensee or applicant will minimize administrative problems associated with the submittal, review and approval of the FNMC plan. Preparation of the plan in accordance with this format Will assist the NRC in evaluating the plan and in standardizing the review and licensing process. However, conformance with this guidance is not required by the NRC. A license applicant who employs a format that provides a equal level of completeness and detail may use their own format. This document is also intended for providing guidance to licensees when making revisions to their FNMC plan.
Date: December 1995
Creator: Joy, D. R.
Partner: UNT Libraries Government Documents Department