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Characterization of Greater-Than-Class C sealed sources. Volume 3, Sealed sources held by general licensees

Description: This is the third volume in a series of three volumes characterizing the population of sealed sources that may become greater-than-Class C low-level radioactive waste (GTCC LLW). In this volume, those sources possessed by general licensees are discussed. General-licensed devices may contain sealed sources with significant amounts of radioactive material. However, the devices are designed to be safe to use without special knowledge of radiological safety practices. Devices containing Am-241 or Cm-244 sources are most likely to become GTCC LLW after concentration averaging. This study estimates that there are about 16,000 GTCC devices held by general licensees; 15,000 of these contain Am-241 sources and 1,000 contain Cm-244 sources. Additionally, this study estimates that there are 1,600 GTCC devices sold to general licensees each year. However, due to a lack of available information on general licensees in Agreement States, these estimates are uncertain. This uncertainty is quantified in the low and high case estimates given in this report, which span approximately an order of magnitude.
Date: September 1, 1994
Creator: Harris, G.
Partner: UNT Libraries Government Documents Department

Demonstration of the SREX process for the removal of {sup 90}Sr from actual highly radioactive solutions in centrifugal contactors

Description: The SREX process is being evaluated at the Idaho Chemical Processing Plant (ICPP) for the separation of {sup 90}Sr from acidic radioactive wastes stored at the ICPP. These efforts have culminated in a recent demonstration of the SREX process with actual tank waste. This demonstration was performed using 24 stages of 2-cm diameter centrifugal contactors installed in a shielded hot cell at the ICPP Remote Analytical Laboratory. An overall removal efficiency of 99.995% was obtained for {sup 90}Sr. As a result, the activity of {sup 90}Sr was reduced from 201 Ci/m{sup 3} in the feed solution of 0.0089 Ci/m{sup 3} in the aqueous raffinate, which is below the U.S. NRC Class A LLW limit of 0.04 Ci/m{sup 3} for {sup 90}Sr. Lead was extracted by the SREX solvent and successfully partitioned from the {sup 90}Sr using an ammonium citrate strip solution. Additionally, 94% of the total alpha activity, 1.9% of the {sup 241}Am, 99.94% of the {sup 238}Pu, 99.97% of the {sup 239}Pu, 36.4% of the K, 64% of the Ba, and >83% of the Zr were extracted by the SREX solvent. Cs, B, Cd, Ca, Cr, Fe, Mn, Ni, and Na were essentially inextractable. 10 refs., 2 figs., 3 tabs.
Date: October 1, 1997
Creator: Law, J.D.; Wood, D.J.; Todd, T.A. & Olson, L.G.
Partner: UNT Libraries Government Documents Department

Area G Perimeter Surface-Soil and Single-Stage Water Sampling: Environmental Surveillance for Fiscal Years 1996 and 1997, Group ESH-19

Description: Area Gin Technical Area 54, has been the principal facility at Los Alamos National Laboratory for the storage and disposal of low-level, solid mixed, and transuranic radioactive waste since 1957. Soil samples were analyzed for tritium, isotopic plutonium, americium-241, and cesium-137. Thirteen metals-silver, arsenic, barium, beryllium, cadmium, chromium, mercury, nickel, lead, antimony, selenium, thallium and zinc-were analyzed on filtered-sediment fractions of the single-stage samples using standard analytical chemistry techniques. During the two years of sampling discussed in this report elevated levels of tritium (as high as 716,000 pCi/L) in soil were found for sampling sites adjacent to the tritium burial shafts located on the south- central perimeter of Area G. Additionally, tritium concentrations in soil as high as 38,300 pCi/L were detected adjacent to the TRU pads in the northeast comer of Area G. Plutonium-238 activities in FY96 soils ranged from 0.001-2.866 pCi/g, with an average concentration of 0.336& 0.734 pCdg. Pu-238 activities in FY97 soils ranged from 0.002-4.890 pCi/g, with an average concentration of 0.437 & 0.928 pCdg. Pu-239 activities in FY96 soils ranged from 0.009 to 1.62 pCdg, with an average of 0.177- 0.297 pCdg. Pu-239 activities in FY97 soils ranged from 0.005 to 1.71 pCi/g, with an average of 0.290- 0.415 pCi/g. The locations of elevated plutonium readings were consistent with the history of plutonium disposal at Area G. The two areas of elevated Am-241 activity reflected the elevated activities found for plutonium, the average values for Am-241 on soils were 0.6-2.07 pCi/g, and 0.10-0.14 pCi/g respectively for samples collected in FY96 and FY97. CS-137 activities in soils had average values of 0.33 pCi/g, and 0.28 pCi/g respectively for samples collected in FY96 and 97. There was no perimeter area where soil concentrations of CS-137 were significantly elevated.
Date: October 1, 1998
Creator: Childs, Marquis & Conrad, Ron
Partner: UNT Libraries Government Documents Department


Description: Two twenty-four inch samples of vertical sections of the cooling coils from Tank 5F, taken from Riser 1, were made available to SRNL by SRR for leaching and characterization of the leachates for select radionuclide trapped in the corrosion layer on the exterior of the cooling coils. One piece of cooling coil sample was obtained from a section of a vertical cooling coil located above the 45-inch elevation from the tank floor and the other also from a vertical section of a cooling coil located below the 45-inch elevation from the tank floor of Tank 5F. Analysis results from both cooling coils show that the predominant radionuclides contributing to the activity in both coils are strontium-90 and cesium-137. The activities for strontium-90 and cesium-137 in the Tank 5F vertical cooling coil located above the 45-inch elevation of the tank and designated as sample 5-R1-A45 averaged 1.34E-02 {+-} 1.12E-03 and 7.27E-04 {+-} 4.46E-05 Ci/ft{sup 2}, respectively, while the activities for the vertical cooling coil located below the 45-inch elevation of the tank and designated as sample 5-R1-B45 averaged 8.93E-03 {+-} 8.25E-04 for Sr-90 and 8.10E-04 {+-} 6.36E-05 Ci/ft{sup 2} for Cs-137. Other significant activity contributing radionuclides are americium-241 and europium-154/155. With the exception of the analysis result for Pu-241 in the 5-R1-A45 cooling coils samples, the target detection limits for the other radionuclides were met in both cooling coil samples. The detection limits for Pu-241 analyses result in coil sample 5-R1-A45 were not met consistently because of possible background changes during counting.
Date: August 17, 2001
Creator: Oji, L. & Diprete, D.
Partner: UNT Libraries Government Documents Department


Description: Nine papers are included which treat the determination of cesium, tritium, americium-241, plutonium, thoron, and other radionuclides under a variety of conditions. One treats the preparation of standard alpha sources. Separate abstracts were prepared for six of the papers; the reraaining three papers were previously abstracted in NSA. (D.L.C.)
Date: October 31, 1963
Partner: UNT Libraries Government Documents Department

Moderation of neutron spectra

Description: Most of the accelerators that produce the various microenergetic neutron sources required for low-energy neutron dosimetry studies have been shut down. One alternative to accelerator-produced sources is the use of fission neutron or ({alpha},n) sources with unique neutron spectra. The problem with this solution is that maintenance of these sources is impractical. To help overcome this impracticality, the authors propose the use of moderating materials to produce a variety of spectra using a minimum number of sources. In the study, they performed Monte Carlo transport calculations under the following conditions: transporting neutrons from bare {sup 252}Cf or {sup 241}Am-Be sources from the center of various-sized spheres; tallying neutron spectra at 50 cm from the source. Of the twelve different moderating materials they studied, they found pure copper to be an ideal moderator. In this paper, they present flux-weighted energies, neutron spectra, and dose information for both {sup 252}Cf and {sup 241}Am-Be sources in bare and six-moderator configurations.
Date: May 1, 1997
Creator: Hsu, H.H. & Chen, J.
Partner: UNT Libraries Government Documents Department

Evaluation of soil radioactivity data from the Nevada Test Site

Description: Since 1951, 933 nuclear tests have been conducted at the Nevada Test Site (NTS) and test areas on the adjacent Tonopah Test Range (TTR) and Nellis Air Force Range (NAFR). Until the early 1960s. the majority of tests were atmospheric, involving detonation of nuclear explosive devices on the ground or on a tower, suspended from a balloon or dropped from an airplane. Since the signing of the Limited Test Ban Treaty in 1963, most tests have been conducted underground, although several shallow subsurface tests took place between 1962 and 1968. As a result of the aboveground and near-surface nuclear explosions, as well as ventings of underground tests, destruction of nuclear devices with conventional explosives, and nuclear-rocket engine tests, the surface soil on portions of the NTS has been contaminated with radionuclides. Relatively little consideration was given to the environmental effects of nuclear testing during the first two decades of operations at the NTS. Since the early 1970s, however, increasingly strict environmental regulations have forced greater attention to be given to contamination problems at the site and how to remediate them. One key element in the current environmental restoration program at the NTS is determining the amount and extent of radioactivity in the surface soil. The general distribution of soil radioactivity on the NTS is already well known as a result of several programs carried out in the 1970s and 1980s. However, questions have been raised as to whether the data from those earlier studies are suitable for use in the current environmental assessments and risk analyses. The primary purpose of this preliminary data review is to determine to what extent the historical data collected at the NTS can be used in the characterization/remediation process.
Date: March 1, 1995
Partner: UNT Libraries Government Documents Department

In situ radiological surveying at the Double Tracks site, Nellis Air Force Range, Tonopah, Nevada

Description: A team from the Remote Sensing Laboratory conducted a series of in situ radiological measurements at the Double Tracks site on the Nellis Air Force Range just east of Goldfield, Nevada, during the periods of April 10-13 and June 5-9, 1995. The survey team measured the terrestrial gamma radiation at the site to determine the levels of natural and man-made radiation. This site includes the areas covered by previous surveys conducted from 1962 through 1993. The main purpose of the first expedition was to assess several new techniques for characterizing sites with dispersed plutonium. The two purposes of the second expedition were to characterize the distribution of transuranic contamination (primarily plutonium) at the site by measuring the gamma rays from americium-241 and to assess the performance of the two new detector platforms. Both of the new platforms performed well, and the characterization of the americium-241 activity at the site was completed. Several plots compare these ground-based system measurements and the 1993 aerial data. The agreement is good considering the systems are characterized and calibrated through independent means. During the April expedition, several methods for measuring the depth distribution of americium-241 in the field were conducted as a way of quickly and reliably obtaining depth profiles without the need to wait for laboratory analysis. Two of the methods were not very effective, but the results of the third method appear very promising.
Date: April 1, 1996
Creator: Riedhauser, S.R. & Tipton, W.J.
Partner: UNT Libraries Government Documents Department

A photon shield capsule design for an {sup 241}Am/Be ({alpha},n) source using high density tungsten alloy

Description: A photon shield capsule made of high density tungsten alloy was designed for a 400 GBq {sup 241}Am/Be ({alpha},n) NIST-traceable source using Monte Carlo calculations. The {sup 241}Am/Be ({alpha},n) source replaces a {sup 239}Pu/Be ({alpha},n) source used in the Los Alamos Neutron Well for dose rate calibrations of portable and fixed neutron rem meters. Potential operator exposure due to {sup 241}Am photon emission (E{sub {gamma}} = 59.5 keV, Y{sub {gamma}} = 0.357 {gamma} d{sup -1}) is a major practical concern in using this type of source. This has been recognized by the International Organization for Standardization (ISO 8529:1989), which recommends wrapping the source in a 1 mm thick lead shield. However, the optimum photon shield capsule design depends on source construction and other considerations. These considerations include minimizing source spectrum degradation and inelastic gamma production from shielding, structural integrity, toxicity, and cost effectiveness of available materials and construction. Investigations of several materials and combinations using stainless steel, high density tungsten alloy (composed of 90%W, 6% Ni and 4% Cu) and lead with various capsule thicknesses were simulated using the Los Alamos Monte Carlo N-Particle Transport Code. The final design was based on a 2 mm thick capsule using the high density tungsten alloy. This material resulted in a small change in the neutron spectrum accompanied with only a slight increase in inelastic gamma production, and unobservable 59.5 keV photon emissions compared to the bare {sup 241}Am/Be ({alpha},n) source.
Date: January 1, 1997
Creator: Clement, R.S.; Hsu, H.H.; Olsher, R.S. & Aikin, D.J.
Partner: UNT Libraries Government Documents Department

Cleanup levels for Am-241, Pu-239, U-234, U-235 & U-238 in soils at the Rocky Flats Environmental Technology Site

Description: This presentation briefly outlines a cleanup program at a Rocky Flats site through viewgraphs and an executive summary. Exposure pathway analyses to be performed are identified, and decontamination levels are listed for open space and office worker exposure areas. The executive summary very briefly describes the technical approach, RESRAD computer code to be used for analyses, recommendations for exposure levels, and application of action levels to multiple radionuclide contamination. Determination of action levels for surface and subsurface soils, based on radiation doses, is discussed. 1 tab.
Date: July 3, 1997
Creator: Roberts, R.; Colby, B.; Brooks, L. & Slaten, S.
Partner: UNT Libraries Government Documents Department

Area G Perimeter Surface-Soil Sampling Environmental Surveillance for Fiscal Year 1998 Hazardous and Solid Waste Group (ESH-19)

Description: Material Disposal Area G (Area G) is at Technical Area 54 at Los Alamos National Laboratory (LANL). Area G has been the principal facility for the disposal of low-level, solid-mixed, and transuranic waste since 1957. It is currently LANL's primary facility for radioactive solid waste burial and storage. As part of the annual environmental surveillance effort at Area G, surface soil samples are collected around the facility's perimeter to characterize possible radionuclide movement off the site through surface water runoff During 1998, 39 soil samples were collected and analyzed for percent moisture, tritium, plutonium-238 and 239, cesium-137 and americium-241. To assess radionuclide concentrations, the results from these samples are compared with baseline or background soil samples collected in an undisturbed area west of the active portion Area G. The 1998 results are also compared to the results from analogous samples collected during 1996 and 1997 to assess changes over this time in radionuclide activity concentrations in surface soils around the perimeter of Area G. The results indicate elevated levels of all the radionuclides assessed (except cesium-137) exist in Area G perimeter surface soils vs the baseline soils. The comparison of 1998 soil data to previous years (1996 and 1997) indicates no significant increase or decrease in radionuclide concentrations; an upward or downward trend in concentrations is not detectable at this time. These results are consistent with data comparisons done in previous years. Continued annual soil sampling will be necessary to realize a trend if one exists. The radionuclide levels found in the perimeter surface soils are above background but still considered relatively low. This perimeter surface soil data will be used for planning purposes at Area G, techniques to prevent sediment tm.nsport off-site are implemented in the areas where the highest radionuclide concentrations are indicated.
Date: September 1, 1999
Creator: Childs, Marquis
Partner: UNT Libraries Government Documents Department