MAM-C - Novel Ideas in Health Physics 1 North 224AB 11:00 - 12:00
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MAM-C.1
11:00 CZT-Based Quantification of the 2019 Nuclear Industry Proficiency Test Exercise Waste Barrel DI Goodman*, H3D, Inc.
; WR Kaye, H3D, Inc.
Abstract: Waste characterization and quantification is traditionally conducted with cryogenically cooled, high-purity germanium (HPGe) detectors. However, the logistical burden of cryogenic cooling required for HPGe detectors, either through liquid nitrogen or Stirling coolers, complicates their use for in-field measurements. Cadmium Zinc Telluride (CZT), a room-temperature semiconductor offering better than 1% energy resolution at 662 keV, is an attractive alternative for in-field waste quantification measurements. The UK’s National Physical Laboratory (NPL) periodically releases waste standards to benchmark the nuclear community’s proficiency in waste characterization. During the 2019 NPL proficiency exercise both HPGe and CZT detectors were used to characterize identical waste barrels. Average results from thirty-five participants using HPGe detectors are directly compared against a CZT-based analysis. Algorithms for Am-241 quantification, which is complicated by the emission of tungsten x-rays from coded aperture tiles used in the CZT detector, are discussed in depth. The value of imaging information, offered by pixelated CZT detectors via coded aperture or Compton imaging, is discussed against traditional assumptions of waste homogeneity for the non-homogenous test barrel.
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MAM-C.2
11:15 Separation of Americium and Curium for Neutron Capture Cross Section Measurements SA Labb*, Colorado State University
; R Sudowe, Colorado State University
Abstract: Assessing the reliability of the U.S. nuclear weapons stockpile without the need for further underground testing is highlighted as one of the major strategies to maintain the existing stockpile. To achieve this goal, accurate information about the neutron capture properties of activation products present in a device’s reaction network is necessary for the design of improved simulation systems that would help to ensure stockpile reliability.
Highly enriched Pu-239 devices contain small amounts of Pu-241, which beta decays resulting in Am-241 buildup. The presence of Am-241 in nuclear weapons gives rise to technological challenges regarding weapons physics and forensics. Previous device tests have shown that neutron capture of Am-241 populates both the metastable and ground state of Am-242 in varying ratios depending on the neutron energy. The population ratio for these two states and its dependence on neutron energy is not well known and diagnostics are complicated by the rare case of a long-lived metastable and short-lived ground state. However, both states will eventually decay to Cm-242. Understanding the relationship between the ratio of populated states and neutron energy can be obtained by irradiating americium targets at various neutron energies; however, the complete separation of Cm-242 from the irradiated target material is required.
Minor actinide separations are challenging due to the nearly identical behavior of these radionuclides. These separations are typically carried out in acidic media, where both americium and curium are in the trivalent oxidation state. However, americium can be oxidized to a higher oxidation state while curium remains in the trivalent oxidation state. Thus, aqueous separation of americium in higher oxidation states from curium can be carried out. This project focuses on the exploitation of redox chemistry towards an efficient separation. We have demonstrated the ion exchange properties of the oxidizing agent, NaBiO3, which led to the development of a chromatographic minor actinide separation method. High separation factors, short contact times, and ease of operation of this separation system provides a promising method. To improve capacity and flow properties, a new chromatographic material with a NaBiO3 coating has been developed in collaboration with TrisKem.
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MAM-C.3
11:30 Design Concept for Molten Salt Reactor Production of Molybdenum-99 using a Helium Bubbling Process Extraction EV Martinez*, Texas A&M University
; AP Macias, Texas A&M University; JK Sexton, Texas A&M University; JJ Mechelsen, Texas A&M University; S Dewji, Texas A&M University
Abstract: The United States has been dependent on foreign countries for its molybdenum-99 (Mo-99) supply, while consuming about 50% of the world's supply. This isotope is a product from the fission of uranium-235 and was produced mainly from aging reactors reaching the end of their lifespan. As these reactors are converted to low-enriched uranium (LEU) fuel or decommissioned, Mo-99 shortages have arisen. A Mo-99 shortage in 2009 has resulted in an unstable supply for diagnostic and medical procedures. Since then, the nuclear medicine industry has been faced with trying to develop new methods to produce Mo-99, domestically. One such proposed method here includes using advanced non-light water reactor concepts, focused on a molten salt reactor (MSR) concept, utilizing a helium bubbling process to remove particulate and gaseous fission products from the core and extract molybdenum from these via an off-line chemical process. As part of a production design concept, the ORNL SCALE code was employed to determine the expected radionuclide inventory. The resulting Mo-99 inventory produced was compared to other LEU options for viability of Mo-99 production. Using dimensional analysis and fluid-mechanical evaluations, the desired helium bubble size and flow rate was determined for maximum molybdenum extraction efficiency. Additionally, a new Type B package for radioactive material, such as Mo-99 is being explored by replacing the typically used polyurethane with sorbothane in the overpack assembly. A risk assessment was completed in RADTRAN to test the structural integrity of this new design. Results from the inventory, bubbling extraction efficiency, and transportation will be presented.
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MAM-C.4
11:45 Low Dose Radiation Treatment For Covid-19 Patients AL Fellman*, NV5 Dade Moeller
Abstract: That the Coronavirus pandemic has caused the death of millions of people worldwide is a tragedy of epic proportions. That many such deaths might have been avoided had moderate and severely ill patients been treated with low dose radiation (LDR) is criminal. It has been well established that prior to the widespread availability of antibiotics and anti-viral medications, LDR was successfully used to treat pneumonia patients (through the 1940s). A combination of forces converged in the mid-1950s which continue to have significant impact on decisions made today. These include Herman Mueller’s Nobel Prize for his work with radiation-induced mutations in fruit flies, the ‘stretching of the truth’ related to radiation risks by many in the geneticist community to ensure continued funding, the efforts by many to link all things radioactive to nuclear weapons proliferation, the National Academy of Science’s adoption and endorsement of the linear no-threshold (LNT) hypothesis, and the birth and maturation of powerful radiation-phobia throughout society (which includes the medical community). After 70 plus years of the LNT and ALARA, the medical profession has been, for the most part, reluctant to utilize LDR to fight Covid-19, despite the lack of available treatment options for severely ill patients. Numerous studies on LDR’s ability to reduce inflammation and improve immune system response in Covid-19 patients will be discussed.
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