368 Matching Results

Search Results

Advanced search parameters have been applied.

Fabrication of 12% {sup 240}Pu calorimetry standards

Description: Throughout the DOE complex, laboratories are performing calorimetric assays on items containing high burnup plutonium. These materials contain higher isotopic range and higher wattages than materials previously encountered in vault holdings. Currently, measurement control standards have been limited to utilizing 6% {sup 240}Pu standards. The lower isotopic and wattage value standards do not complement the measurement of the higher burnup material. Participants of the Calorimetry Exchange (CALEX) Program have identified the need for new calorimetric assay standards with a higher wattage and isotopic range. This paper describes the fabrication and verification measurements of the new CALEX standard containing 12% {sup 240}Pu oxide with a wattage of about 6 to 8 watts.
Date: August 1, 1995
Creator: Long, S.M.; Hildner, S.; Gutierrez, D.; Mills, C.; Garcia, W. & Gurule, C.
Partner: UNT Libraries Government Documents Department

Tank 241-AN-104, cores 163 and 164 analytical results for thefinal report

Description: This document is the analytical laboratory report for tank 241-AN-104 push mode core segments collected between August 8, 1996 and September 12, 1996. The segments were subsampled and analyzed in accordance with the Tank 241-AAr-1 04 Push Mode Core Sampling and Analysis Plan (TSAP) (Winkleman, 1996), the Safety Screening Data Quality Objective (DQO) (Dukelow, et at., 1995) and the Flammable Gas Data Quality Objective (DQO) (Benar, 1995). The analytical results are included in a data summary table. None of the samples submitted for Differential Scanning Calorimetry (DSC), Total Alpha Activity (AT), Total Organic Carbon (TOC) and Plutonium analyses (239,240 Pu) exceeded notification limits as stated in the TSAP. The statistical results of the 95% confidence interval on the mean calculations are provided by the Tank Waste Remediation Systems Technical Basis Group in accordance with the Memorandum of Understanding (Schreiber, 1997) and not considered in this report.
Date: June 5, 1997
Creator: Steen, F.H.
Partner: UNT Libraries Government Documents Department

An overview of the ORNL-NFS intercomparison

Description: Nuclear Fuel Services sent more than 800 drums of nuclear waste to Oak Ridge National Laboratory, with the majority of the waste packaged into five different waste matrix types. A thorough and complete assay of the waste was performed at both NFS and at ORNL. A detailed comparing of the two assay sets provides valuable. insights into problems encountered in typical assay campaigns, particularly as there is, for the most part, excellent agreement between these two campaigns.
Date: February 1, 1997
Creator: Hensley, D.C.
Partner: UNT Libraries Government Documents Department

NMIS Time Correlations for Determining the Shape of Plutonium Using Second Order Statistics

Description: The Nuclear Materials Identification System (NMIS) detector-detector cross correlation signatures collected from passive measurements for plutonium assemblies are highly sensitive to its position with respect to the detectors. This position sensitivity coupled with an optimum configuration of four detectors about the assembly can theoretically be used to extract the shape distribution of the {sup 240}Pu in the assembly. This process is currently being simulated at the Oak Ridge National Laboratory by using four detectors arranged in a tetrahedron and {sup 252}Cf sources as surrogates for the {sup 240}Pu.
Date: July 11, 2001
Creator: Chiang, L.G.
Partner: UNT Libraries Government Documents Department

Sediment studies at Bikini Atoll part 2. inventories of transuranium elements in surface sediments

Description: This is the second of three reports on Bikini sediment studies, which discusses the concentrations and inventories of {sup 241}Am and {sup 239+240}Pu in sediments from the lagoon. Surface sediment samples were collected from 87 locations over the entire lagoon at Bikini Atoll during 1979. The collections were made to map the distribution of long-lived radionuclides associated with the bottom material and to show what modifications occurred in the composition of the sediment as a result of the testing program. Present inventories for {sup 241}Am and {sup 239+240}Pu in the surface 2 cm of sediment are estimated to be 14 and 17 TBq, respectively. These values are estimated to represent only 14% of the total inventory in the sediment column. Sediment inventories of {sup 239+240}Pu and {sup 241}Am are changing only slowly with time through chemical- physical processes that continuously mobilize small amounts of the transuranics to the water column. The lowest concentrations and inventories are associated with deposits logoonward of the eastern reef.
Date: October 1, 1997
Creator: Noshkin, V. E.; Eagle, R. J.; Wong, K. M. & Robison, W. L.
Partner: UNT Libraries Government Documents Department

Low energy gamma-transitions in Pu{sup 238} and Pu{sup 240}

Description: We investigated electron and gamma spectra of mixtures of isotopes of curium. This was done on a beta spectrometer with double focusing at an angle of {pi}{radical}2 and on a scintillation gamma spectrometer with a 40 {times} 40 mm NAI(Tl) single crystal detector. The observed electron spectrum are interpolated and presented. Also, experimental results of the ratio of conversion at L and M subshells are presented and compared to theoretical values.
Date: March 27, 1967
Creator: Akalaev, G. G.; Vartanov, N. A. & Samoilov, P. S.
Partner: UNT Libraries Government Documents Department

SUR, a program to generate error covariance files

Description: Covariance matrices were calculated for the $sup 238$U, $sup 241$Pu, and $sup 239$Pu fission cross sections and for the $sub 23$$sub 8$ $sup 240$Pu, $sup 241$Pu, and $sup 239$Pu capture cross sections. A computer program was written which uses the evaluated ENDF/B data files and the measured or evaluated (from other evaluations) cross sections for the calculation of the uncertainty files. An effort has been made to make the output of the program consistent with the ENDF/B error files format. A user's manual for the present code and references utilized in the covariance matrix calculations are given. (auth)
Date: March 1, 1976
Creator: Difilippo, F.C.
Partner: UNT Libraries Government Documents Department


Description: In nuclear material processing facilities, it is often necessary to balance the competing demands of accuracy and throughput. While passive neutron multiplicity counting is the preferred method for relatively fast assays of plutonium, the presence of low-Z impurities (fluorine, beryllium, etc.) rapidly erodes the assay precision of passive neutron counting techniques, frequently resulting in unacceptably large total measurement uncertainties. Conversely, while calorimeters are immune to these impurity effects, the long count times required for high accuracy can be a hindrance to efficiency. The higher uncertainties in passive neutron measurements of impure material are driven by the resulting large (>>2) {alpha}-values, defined as the ({alpha},n):spontaneous fission neutron emission ratio. To counter impurity impacts for high-{alpha} materials, a known-{alpha} approach may be adopted. In this method, {alpha} is determined for a single item using a combination of gamma-ray and calorimetric measurements. Because calorimetry is based on heat output, rather than a statistical distribution of emitted neutrons, an {alpha}-value determined in this way is far more accurate than one determined from passive neutron counts. This fixed {alpha} value can be used in conventional multiplicity analysis for any plutonium-bearing item having the same chemical composition and isotopic distribution as the original. With the results of single calorimeter/passive neutron/gamma-ray measurement, these subsequent items can then be assayed with high precision and accuracy in a relatively short time, despite the presence of impurities. A calorimeter-based known-{alpha} multiplicity analysis technique is especially useful when requiring rapid, high accuracy, high precision measurements of multiple plutonium bearing items having a common source. The technique has therefore found numerous applications at the Savannah River Site. In each case, a plutonium (or mixed U/Pu) bearing item is divided into multiple containers. A single item from that batch is then selected for both neutron and calorimetric measurements; all remaining items undergo a ...
Date: February 21, 2012
Creator: Dubose, F.
Partner: UNT Libraries Government Documents Department


Description: The fission cross section of Pu/sup 240/ was determimed from Pu/sup 240/U/sup 235/ ratio for neutron energies between threshold and 8.1 Mev. U/sup 235/ cross section values were essentially those given in a recent compilation in ''Progress in Nuclear Energy.'' The technique used was to mount the two foils back-to-back in a double ionization chamber and to irradiate them in a neutron flux of variable energy. (A.C.)
Date: February 1, 1957
Creator: Henkel, R.L.; Nobles, R.A. & Smith, R.K.
Partner: UNT Libraries Government Documents Department

Uncertainty analysis for determination of plutonium mass by neutron multiplicity counting

Description: This paper describes an uncertainty analysis carried out in association with the use of neutron multiplicity counting to collect data, and assign a total plutonium mass. During 1997, the Los Alamos Safeguards Science and Technology Group carried out careful calorimetry and neutron multiplicity certification measurements on two {sup 239}Pu metal foils used as reference standards at the Idaho National Environmental Engineering Laboratory (INEEL). The foils were measured using a five ring neutron multiplicity counter designed for neutron measurement control activities. This multiplicity counter is well characterized, and the detector parameters were reaffirmed before the measurements were made using several well-known Los Alamos standards. Then, the {sup 240}Pu effective mass of the foils was determined directly from the multiplicity analysis without a conventional calibration curve based on representative standards. Finally, the {sup 240}Pu effective mass fraction and the total plutonium mass was calculated using gamma ray isotopics. Errors from statistical data collection, background subtraction, cosmic ray interaction, dead time corrections, calibration constants, sample geometry, and sample position were carefully estimated and propagated. The authors describe these error sources, the final calculated relative error in the foil assay, and the comparison with very accurate calorimetry measurements.
Date: December 31, 1998
Creator: Carrillo, L.A.; Ensslin, N.; Krick, M.S.; Langner, D.G. & Rudy, C.R.
Partner: UNT Libraries Government Documents Department

Measurement of plutonium and uranium isotopic abundances by gamma-ray spectrometry

Description: The isotopic composition of plutonium and uranium is needed for purposes of sample confirmation, or for interpreting results from calorimeters or neutron-coincidence measurement instruments to determine nuclear material mass. The authors have developed measurement methods and computer codes utilizing high-resolution gamma-ray spectrometry to measure the relative isotopic abundances of plutonium and uranium in various forms nondestructively. The computer codes, known as MGA and MGAU, have unique analysis methodologies that the authors briefly describe in this paper.
Date: February 1, 1996
Creator: Ruhter, W.D. & Gunnink, R.
Partner: UNT Libraries Government Documents Department

Radionuclide Concentrations in Deer and Elk from Los Alamos National Laboratory: 1991-1998

Description: Mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) forage in many areas at Los Alamos National Laboratory (LANL) that may contain radioactivity above natural and/or worldwide fallout levels. This paper summarizes radionuclide concentrations 3H, 90Sr, 137Cs, 238Pu, 239,240Pu, 241Am, and total uranium in muscle and bone tissue of deer and elk collected from LANL lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer and elk collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer and elk collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDES (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (51 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.220, deer bone = 3.762, elk muscle = 0.117, and elk bone = 1.67 mrendy. AU CEDES were far below the International Commission on Radiological Protection guideline of 100 mrem/y, and the highest muscle plus bone CEDE (4.0 mrendy) corresponded to a RECF of 2E-06 which is far below the Environmental ...
Date: December 1, 1998
Creator: Kraig, D. H.; Ferenbaugh, J. K.; Biggs, J. R.; Bennett, K. D.; Mullen, M. A. & Fresquez, P. R.
Partner: UNT Libraries Government Documents Department

Ambient air sampling for radioactive air contaminants at Los Alamos National Laboratory: A large research and development facility

Description: This paper describes the ambient air sampling program for collection, analysis, and reporting of radioactive air contaminants in and around Los Alamos National Laboratory (LANL). Particulate matter and water vapor are sampled continuously at more than 50 sites. These samples are collected every two weeks and then analyzed for tritium, and gross alpha, gross beta, and gamma ray radiation. The alpha, beta, and gamma measurements are used to detect unexpected radionuclide releases. Quarterly composites are analyzed for isotopes of uranium ({sup 234}U, {sup 235}U, {sup 238}U), plutonium ({sup 238}Pu, {sup 239/249}Pu), and americium ({sup 241}Am). All of the data is stored in a relational database with hard copies as the official records. Data used to determine environmental concentrations are validated and verified before being used in any calculations. This evaluation demonstrates that the sampling and analysis process can detect tritium, uranium, plutonium, and americium at levels much less than one percent of the public dose limit of 10 millirems. The isotopic results also indicate that, except for tritium, off-site concentrations of radionuclides potentially released from LANL are similar to typical background measurements.
Date: September 1, 1998
Creator: Eberhart, C.F.
Partner: UNT Libraries Government Documents Department

Radionuclide concentrations in honey bees from Area G at TA-54 during 1997. Progress report

Description: Honey bees were collected from two colonies located at Los Alamos National Laboratory`s Area G, Technical Area 54, and from one control (background) colony located near Jamez Springs, NM. Samples were analyzed for the following: cesium ({sup 137}Cs), americium ({sup 241}Am), plutonium ({sup 238}Pu and {sup 239,240}Pu), tritium ({sup 3}H), total uranium, and gross gamma activity. Area G sample results from both colonies were higher than the upper (95%) level background concentration for {sup 238}Pu and {sup 3}H.
Date: July 1, 1998
Creator: Haarmann, T.K. & Fresquez, P.R.
Partner: UNT Libraries Government Documents Department

The underwater coincidence counter for plutonium measurements in mixed-oxide fuel assemblies manual

Description: This manual describes the Underwater Coincidence Counter (UWCC) that has been designed for the measurement of plutonium in mixed-oxide (MOX) fuel assemblies prior to irradiation. The UWCC uses high-efficiency {sup 3}He neutron detectors to measure the spontaneous-fission and induced-fission rates in the fuel assembly. Measurements can be made on MOX fuel assemblies in air or underwater. The neutron counting rate is analyzed for singles, doubles, and triples time correlations to determine the {sup 240}Pu effective mass per unit length of the fuel assembly. The system can verify the plutonium loading per unit length to a precision of less than 1% in a measurement time of 2 to 3 minutes. System design, components, performance tests, and operational characteristics are described in this manual.
Date: May 1, 1999
Creator: Eccleston, G. W.; Menlove, H. O.; Abhold, M.; Baker, M. & Pecos, J.
Partner: UNT Libraries Government Documents Department