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Analysis of gas-cooled fast reactor shield designs

Description: In its shielding program for the Gas-Cooled Fast Reactor (GCFR) as conceived by General Atomic, Oak Ridge National Laboratory has developed an advanced shielding analysis system that incorporates the latest analysis techniques for converging to a shield design compatible with other design parameters such as cooling and structural requirements or material compatibility. Basically the system consists in applying the various techniques in a logical sequence to a given design, thereby generating a large body of data to serve as an information base for subsequent redesign. As an illustration, this system is applied to successive typical models for the GCFR, resulting in a reduction in the thickness of the radial shield and redesign of the lower shield region. In principle, the design-analysis-redesign iterations would continue until they converge upon an acceptable configuration.
Date: January 1, 1978
Creator: Bartine, D.E. & Williams, L.R.
Partner: UNT Libraries Government Documents Department

Probabilistic methodology for estimating radiation-induced cancer risk

Description: The RICRAC computer code was developed at Oak Ridge National Laboratory to provide a versatile and convenient methodology for radiation risk assessment. The code allows as input essentially any dose pattern commonly encountered in risk assessments for either acute or chronic exposures, and it includes consideration of the age structure of the exposed population. Results produced by the analysis include the probability of one or more radiation-induced cancer deaths in a specified population, expected numbers of deaths, and expected years of life lost as a result of premature fatalities. These calculatons include consideration of competing risks of death from all other causes. The program also generates a probability frequency distribution of the expected number of cancers in any specified cohort resulting from a given radiation dose. The methods may be applied to any specified population and dose scenario.
Date: January 1, 1981
Creator: Dunning, D.E. Jr.; Leggett, R.W. & Williams, L.R.
Partner: UNT Libraries Government Documents Department

BNCT filter design studies for the ORNL Tower Shielding Facility

Description: Boron Neutron Capture Therapy (BNCT) in the United States has entered into a new phase with the initiation of clinical trials using neutron sources at the Brookhaven National Laboratory and the Massachusetts Institute of Technology. If these trials are successful at demonstrating the efficacy of BNCT as a viable treatment for glioblastoma multiforme, then there will be an immediate demand for several additional neutron sources in order to treat the several thousand patients currently diagnosed with glioblastomas in the U.S. each year. However, the requirements for an acceptable neutron source for BNCT are rather severe in terms of the need to provide a sufficient number of epithermal neutrons to a patient-accessible location in a reasonable time with minimal thermal-neutron, fast- neutron, and gamma-ray background. A recent study of potential neutron sources at Oak Ridge National Laboratory (ORNL) has been completed, which concludes that the Tower Shielding Facility (TSF), also appears very well suited for BNCT. The light-water-cooled reactor is contained in an aluminum pressure vessel and located in a large concrete `bunker` referred to as the Big Beam Shield (BBS). The BBS contains a 77-cm-diameter beam collimator, which permits access to a broad beam neutron flux exceeding 4 x 10[sup ll] Cm[sup -2]s[sup- 1] at the operational power of 1 MW. The collimated beam emerges horizontally onto an unenclosed test pad area on which shield mockups were assembled. The appropriate beam filter and collimator system can be easily constructed in the expansive area previously used for the large shield mockups. Additional engineering of the beam shutter mechanism and the construction of treatment support facilities will be needed but can be easily accommodated on the remote dedicated site. The filter design analysis is provided.
Date: December 31, 1996
Creator: Ingersoll, D.T.; Slater, C.O. & Williams, L.R.
Partner: UNT Libraries Government Documents Department

Development of Soft Ionization for Particulate Organic Detection with the Aerodyne Aerosol Mass Spectrometer

Description: During this DOE SBIR Phase II project, we have successfully developed several soft ionization techniques, i.e., ionization schemes which involve less fragmentation of the ions, for use with the Aerodyne time-of-flight aerosol mass spectrometer (ToF-AMS). Vacuum ultraviolet single photon ionization was demonstrated in the laboratory and deployed in field campaigns. Vacuum ultraviolet single photon ionization allows better identification of organic species in aerosol particles as shown in laboratory experiments on single component particles, and in field measurements on complex multi-component particles. Dissociative electron attachment with lower energy electrons (less than 30 eV) was demonstrated in the measurement of particulate organics in chamber experiments in Switzerland, and is now a routine approach with AMS systems configured for bipolar, negative ion detection. This technique is particularly powerful for detection of acidic and other highly oxygenated secondary organic aerosol (SOA) chemical functionality. Low energy electron ionization (10 to 12 eV) is also a softer ionization approach routinely available to AMS users. Finally, Lithium ion attachment has been shown to be sensitive to more alkyl-like chemical functionality in SOA. Results from Mexico City are particularly exciting in observing changes in SOA molecular composition under different photochemical/meteorological conditions. More recent results detecting biomass burns at the Montana fire lab have demonstrated quantitative and selective detection of levoglucosan. These soft ionization techniques provide the ToF-AMS with better capability for identifying organic species in ambient atmospheric aerosol particles. This, in turn, will allow more detailed study of the sources, transformations and fate of organic-containing aerosol.
Date: June 19, 2008
Creator: Trimborn, A; Williams, L R; Jayne, J T & Worsnop, D R
Partner: UNT Libraries Government Documents Department

Comparisons of TORT and MCNP dose calculations for BNCT treatment planning

Description: The relative merit of using a deterministic code to calculate dose distributions for BNCT applications were examined. The TORT discrete deterministic ordinated code was used in comparison to MCNP4A to calculate dose distributions for BNCT applications
Date: December 31, 1996
Creator: Ingersol, D.T.; Slater, C.O.; Williams, L.R.; Redmond, E.L., II & Zamenhof, R.G.
Partner: UNT Libraries Government Documents Department

A Blood Circulation Model for Reference Man

Description: A dynamic blood circulation model that predicts the movement and gradual dispersion of a bolus of material in the circulation after its intravenous injection into an adult human. The main purpose of the model is improve the dosimetry of internally deposited radionuclides that decay in the circulation to a significant extent. The model partitions the blood volume into 24 separate organs or tissues, right heart chamber, left heart chamber, pulmonary circulation, arterial outflow to the aorta and large arteries, and venous return via the large veins. Model results were compared to data obtained from injection of carbon 11 labeled carbon monoxide or rubidium 86.
Date: December 1996
Creator: Leggett, R. W.; Eckerman, K. F. & Williams, L. R.
Partner: UNT Libraries Government Documents Department

Measurements of Black Carbon Particles Chemical, Physical, and Optical Properties

Description: Accurate measurements of the chemical, physical, and optical properties of aerosol particles containing black carbon are necessary to improve current estimates of the radiative forcing in the atmosphere. A collaborative research effort between Aerodyne Research, Inc. and Boston College has focused on conducting field and laboratory experiments on carbonaceous particles and the development and characterization of new particulate instrumentation. This presentation will focus on the chemical, physical, and optical properties of black carbon particles measured in the laboratory in order to understand the effects of atmospheric processing on black carbon particles. Results from a three-week study during July 2008 of mass- and optical-based black carbon measurements will be presented. The project utilized the Boston College laboratory flame apparatus and aerosol conditioning and characterization equipment. A pre-mixed flat flame burner operating at controlled fuel-to-air ratios produced stable and reproducible concentrations of soot particles with known sizes, morphologies, and chemical compositions. In addition, other black carbon particle types, including fullerene soot, glassy carbon spheres, oxidized flame soot, Regal black, and Aquadag, were also atomized, size selected, and sampled. The study covered an experimental matrix that systematically selected particle mobility size (30 to 300 nm) and black carbon particle mass, particle number concentration, particle shape (dynamic shape factor and fractal dimension), and particle chemistry and density (changed via coatings). Particles were coated with a measured thickness (few nm to {approx}150 nm) of sulfuric acid or bis (2-ethylhexyl) sebacate and passed through a thermal denuder to remove the coatings. Highlights of the study to be presented include: (1) Characterization of the chemical and physical properties of various types of black carbon particles, (2) Mass specific absorption measurements as a function of fuel-to-air ratio and carbon particle type, (3) Optical absorption nhancement measurements as a function of coatings, and (4) Particle shape determination as a ...
Date: December 14, 2009
Creator: Onasch, T.B.; Sedlacek, A.; Cross, E. S.; Davidovits, P.; Worsnop, D. R.; Ahern, A. et al.
Partner: UNT Libraries Government Documents Department