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Radiation Doses to Hanford Workers from Natural Potassium-40

Description: The chemical element potassium is an essential mineral in people and is subject to homeostatic regulation. Natural potassium comprises three isotopes, 39K, 40K, and 41K. Potassium-40 is radioactive, with a half life of 1.248 billion years. In most transitions, it emits a β particle with a maximum energy of 0.560 MeV, and sometimes a gamma photon of 1.461 MeV. Because it is ubiquitous, 40K produces radiation dose to all human beings. This report contains the results of new measurements of 40K in 248 adult females and 2,037 adult males performed at the Department of Energy Hanford Site in 2006 and 2007. Potassium concentrations diminish with age, are generally lower in women than in men, and decrease with body mass index (BMI). The average annual effective dose from 40K in the body is 0.149 mSv y−1 for men and 0.123 mSv y−1 women respectively. Averaged over both men and women, the average effective dose per year is 0.136 mSv y−1. Calculated effective doses range from 0.069 to 0.243 mSv y−1 for adult males, and 0.067 to 0.203 mSv y−1 for adult females, a roughly three-fold variation for each gender. The need for dosimetric phantoms with a greater variety of BMI values should be investigated. From our data, it cannot be determined whether the potassium concentration in muscle in people with large BMI values differs from that in people with small BMI values. Similarly, it would be important to know the potassium concentration in other soft tissues, since much of the radiation dose is due to beta radiation, in which the source and target tissues are the same. These uncertainties should be evaluated to determine their consequences for dosimetry.
Date: February 13, 2009
Creator: Strom, Daniel J.; Lynch, Timothy P. & Weier, Dennis R.
Partner: UNT Libraries Government Documents Department


Description: One of the important that the U.S. Department of Energy (DOE) is currently undertaking is the development of a high-level nuclear waste repository to be located at Yucca Mountain, Nevada. Concern is generated by the Yucca Mountain Project (YMP) is due to potential releases as groundwater contamination, as described in the Total System Performance Assessment (TSPA). The dose to an off-site individual using this groundwater for drinking and irrigation is dominated by four radionuclides: Tc-99, I-127, Np-237, and U-238. Ideally, this dose would be limited to a single radionuclide, U-238; in other words, YMP would resemble a uranium ore body, a common geologic feature in the Western U.S. For this reason and because of uncertainties in the behavior of Tc-99, I-127, and Np-237, it would be helpful to limit the amount of Tc, I, and Np leaving the repository, which would greatly increase the confidence in the long-term performance of YMP. An approach to limiting the migration of Tc, I, and Np that is complementary to the existing YMP repository design plans is to employ sequestering agents or ''getters'' for these radionuclides such that their migration is greatly hindered, thus decreasing the amount of radionuclide leaving the repository. Development of such getters presents a number of significant challenges. The getter must have a high affinity and high selectivity for the radionuclide in question since there is approximately a 20- to 50-fold excess of other fission products and a 1000-fold excess of uranium in addition to the ions present in the groundwater. An even greater challenge is that the getters must function over a period greater than the half-life of the radionuclide (greater than 5 half-lives would be ideal). Typically, materials with a high affinity for Tc, I, or Np are not sufficiently durable. For example, strong-base ion exchange resins have ...
Date: March 13, 2006
Creator: Holt, K. C.
Partner: UNT Libraries Government Documents Department

Fission Product Traps for Use in High-Temperature Gas-Cooled Graphite Reactors

Description: A proposal is given of an approach to a fission-product trapping system which appears feasible on the basis of thermodynamic and other data available. Reactor and trapping conditions are outlined. The half-lives, fission yields, and volatility of the fission products of interest are described. To provide the most effective retention at elevated temperatures, two types of reagents are required: a highly electropositive metal that will not melt or appreciably vaporize and which will form stable non-volatile compounds with non-metallic or near non-metallic fission products; and a reagent to provide a highly electronegative element to form stable, non-volatile compounds with metallic fission products. Thermodynamic properties are included for compounds formed by reactions between the fission products and the trapping reagents. (B.O.G.)
Date: March 13, 1958
Creator: Zumwalt, L. R.
Partner: UNT Libraries Government Documents Department


Description: Neutral hyperons produced by 5-Bev The effects of /sup -/ mesons incident on a large propane bubble chamber are analyzed in detail with respect to production cross sections and angular distributions of production and decays and the A lifetime is measured. The cross section for neutralhyperon (Y/sup 0/) production by the reaction The effects of /sup -/ + p 1100 deg C are Y/sup 0/ + K is 0.98 sintering time 0.16 mb. The cross section for carbon mpacting ( The effects of - + C 1100 deg C are Y/sup 0/ + K) is 6.05 sintering time 0.89 mb. The mean Svlvania Electr decay time is (3.12 sintering time 0.34) x 10/sup -10/ sec. The corrected lifetime is observed to be (3.23 sintering time 0.36) x 10/sup -10/ sec. Although the up-down decay asymmetry for Svlvania Electr hyperons is not significantly different from zero, the fore-aft decay angular distribution is asymmetric; alpha P = -0.31 sintering time 0.12 where the decay proton distribrtion along the Svlvania Electr direction of motion has been examined. This is suggested as evidence for nonconservation of parity in the production interaction. The Svlvania Electr -production angular distribution is peaked backward in the production center of mass. The A momentum spectrum and the distribution of Svlvania Electr production star prongs are presented. Sources of bias and their correction are discussed, and an estimate is made of the carbon contamination of the events that contribute to the hydrogen cross section for a production. (auth)
Date: April 13, 1959
Creator: Hotz, D F
Partner: UNT Libraries Government Documents Department

Proton Radioactivity Measurements at HRIBF: Ho, Lu, and Tm Isotopes

Description: Two new isotopes, {sup 145}Tm and {sup 140}Ho and three isomers in previously known isotopes, {sup 141m}Ho, {sup 150m}Lu and {sup 151m}Lu have been discovered and studied via their decay by proton emission. These proton emitters were produced at the Holifield Radioactive Ion Beam Facility (HRIBF) by heavy-ion fusion-evaporation reactions, separated in A/Q with a recoil mass spectrometer (RMS), and detected in a double-sided silicon strip detector (DSSD). The decay energy and half-life was measured for each new emitter. An analysis in terms of a spherical shell model is applied to the Tm and Lu nuclei, but Ho is considerably deformed and requires a collective model interpretation.
Date: November 13, 1998
Creator: Akovali, Y.; Batchelder, J.C.; Bingham, C.R.; Davinson, T.; Ginter, T.N.; Gross, C.J. et al.
Partner: UNT Libraries Government Documents Department

''Yields of Radionuclides Created by Photonuclear Reactions on Be, C, Na, C1, and Ge, Using Bremsstrahlung of 150-MeV Electrons''

Description: The bremsstrahlung created by 150-MeV electrons impinging on a tantalum radiator was used to study photonuclear reactions on samples containing Be, C, Na, Cl and Ge. For Ge fifteen radioisotopes, ranging in half life between 2.6 min and 271 days, and in mass between 65 and 75, were obtained in sufficient amount to determine their yields quantitatively using known decay gamma-rays. Special equipment is described which was developed to create the bremsstrahlung using a beam-sharing mode, while minimizing the neutron flux on the sample. Relative production rates were determined. These were analyzed to provide absolute average cross sections for production of three reactions: <{sigma}> for {sup 35}Cl({gamma}, n) {sup 34}Cl{sup isom}- = 4.7 mb; <{sigma}> for {sup 70}Ge({gamma}, n){sup 69}Ge = 56 mb; and <{sigma}> for {sup 76}Ge({gamma}, n){sup 75}Ge = 53 mb, where the ({gamma}, n) values are averages over the giant resonances of the stable target isotopes.
Date: December 13, 2001
Creator: Dickens, J.K.
Partner: UNT Libraries Government Documents Department