http://hdl.handle.net/1957/18497 Wed, 19 Jun 2013 02:29:07 GMT 2013-06-19T02:29:07Z http://hdl.handle.net/1957/39510 Design and analysis of radiation shielding eyewear Spackman, David A. The recent reductions to the international dose limit recommendations for the lens of the eye have renewed interest in radiation protection strategies in interventional fluoroscopy, where eye-lens radiation exposure occurs frequently. Radiationshielding eyewear can significantly reduce lens dose in these scenarios, but accurate protection factors are elusive because they depend on a variety of factors. This work aims to investigate variables that affect eye shield performance in fluoroscopy rooms, test several shield designs, and rate the shield designs based on shielding performance. Eight separate shields were modeled in MCNP5 using detailed head and eye geometry, and the shields were evaluated at eight individual source positions. Results showed that shields of different thicknesses and shapes can provide similar protection to the operator. A total protection factor of about 5 is the most protection a 0.10 mm lead equivalent material can reasonably provide, and small shields constructed of this material can provide protection factors of about 3. Shield performance can vary greatly depending on the irradiation angle, and this could cause an overestimation of the dose reduction provided by the shield if vulnerable angles are exploited. With increasing evidence of cataract risk at low lens doses, fluoroscopy operators need radiation protection equipment that can provide well characterized protection, and radiation-shielding eyewear can provide excellent dose reduction if they are designed well and used correctly. Graduation date: 2013 Tue, 11 Jun 2013 00:00:00 GMT http://hdl.handle.net/1957/39510 2013-06-11T00:00:00Z http://hdl.handle.net/1957/39392 Characterization of fission product transport in a gen. IV gas-cooled fast reactor plant utilizing vented fuel Deason, Wesley Fission product transport in a Gen. IV Gas-Cooled Fast Reactor Plant utilizing vented fuel has been characterized using analytical and computational methods. The goal was to increase current understanding of fission product transport in helium-cooled GFRs using vented fuel and to provide a toolset for determining issues which may arise during normal and abnormal operating conditions. A review of the Peach Bottom Unit 1 reactor, the Gas-Cooled Fast Reactor, the Gen IV Gas-Cooled Fast Reactor, and the Energy Multiplier Module—all helium-cooled nuclear systems utilizing vented fuel—provided sufficient background for understanding the design methodology behind vented system and helium purification system design. From documentation for these systems and other literature, the phenomena of fission product generation and decay, volatile fission product chemistry, fission product diffusion and release in fuel, fission product leakage through non-fuel components, fission product plateout, and collection of gaseous fission products through adsorption in the charcoal beds were identified as having a significant effect on the transport of fission products within a vented fuel system. Understanding of vented fuel system design and identified fission product transport phenomena was then used for the development of a vented fuel system model in the systems modeling program, STELLA. The model was used to analyze test cases, characterizing the time-dependent accumulation and decay of fission products in a vented fuel system. These results, used in conjunction with the review of past systems, were used to compile conclusions and recommendations for the design of vented fuel systems and helium purification systems, aiding direction of future research and design efforts. Briefly, the work found that the mass, activity, and power generation of accumulated fission products is likely to be very large, requiring significant consideration within the overall plant design. Additionally, the reduction of the source of vented fission products being purged from the primary vessel, either by fuel or core design, may present significant advantages in plant design. It was also found that safety systems will be necessary to prevent overheat and possible release from the helium purification system in the case of an accident scenario. Lastly, it was found that the determination of the purge stream leakage rate into the primary coolant and the fuel release rate are of crucial importance for the safety and economy of a vented fuel system. This work was funded as part of a Nuclear Energy University Programs Grant from the Department of Energy. Graduation date: 2013 Fri, 31 May 2013 00:00:00 GMT http://hdl.handle.net/1957/39392 2013-05-31T00:00:00Z http://hdl.handle.net/1957/38468 Preliminary framework for the run-ahead predictive simulation software (RAPSS) Makinson, Kevin A. The Run-Ahead Predictive Simulation Software (RAPSS) is an architecture designed for faster-than-real-time decision support for operators of complex networks. To enable further development of the RAPSS methodology, the necessary proof of principle is illustrated in two applications: decision support for shift technical advisors in nuclear power plant control rooms (RAPSS-STA), and in the event of a release outside of containment, decision support for emergency operation centers (RAPSS-EOC). Graduation date: 2013 Fri, 19 Apr 2013 00:00:00 GMT http://hdl.handle.net/1957/38468 2013-04-19T00:00:00Z http://hdl.handle.net/1957/38431 Experimental shielding evaluation of the radiation protection provided by residential structures Dickson, Elijah D. The human health and environmental effects following a postulated accidental release of radioactive material to the environment has been a public and regulatory concern since the early development of nuclear technology and researched extensively to better understand the potential risks for accident mitigation and emergency planning purposes. The objective of this investigation is to research and develop the technical basis for contemporary building shielding factors for the U.S. housing stock. Building shielding factors quantify the protection a certain building-type provides from ionizing radiation. Much of the current data used to determine the quality of shielding around nuclear facilities and urban environments is based on simplistic point-kernel calculations for 1950’s era suburbia and is no longer applicable to the densely populated urban environments seen today. To analyze a building’s radiation shielding properties, the ideal approach would be to subject a variety of building-types to various radioactive materials and measure the radiation levels in and around the building. While this is not entirely practicable, this research uniquely analyzes the shielding effectiveness of a variety of likely U.S. residential buildings from a realistic source term in a laboratory setting. Results produced in the investigation provide a comparison between theory and experiment behind building shielding factor methodology by applying laboratory measurements to detailed computational models. These models are used to develop a series of validated building shielding factors for generic residential housing units using the computational code MCNP5. For these building shielding factors to be useful in radiologic consequence assessments and emergency response planning, two types of shielding factors have been developed for; (1) the shielding effectiveness of each structure within a semi-infinite cloud of radioactive material, and (2) the shielding effectiveness of each structure from contaminant deposition on the roof and surrounding surfaces. For example, results from this investigation estimate the building shielding factors from a semi-infinite plume between comparable two-story models with a basement constructed with either brick-and-mortar or vinyl siding composing the exterior wall weather and a typical single-wide manufactured home with vinyl siding to be 0.36, 0.65, and 0.82 respectively.; The human health and environmental effects following a postulated accidental release of radioactive material to the environment has been a public and regulatory concern since the early development of nuclear technology and researched extensively to better understand the potential risks for accident mitigation and emergency planning purposes. The objective of this investigation is to research and develop the technical basis for contemporary building shielding factors for the U.S. housing stock. Building shielding factors quantify the protection a certain building-type provides from ionizing radiation. Much of the current data used to determine the quality of shielding around nuclear facilities and urban environments is based on simplistic point-kernel calculations for 1950’s era suburbia and is no longer applicable to the densely populated urban environments seen today. To analyze a building’s radiation shielding properties, the ideal approach would be to subject a variety of building-types to various radioactive materials and measure the radiation levels in and around the building. While this is not entirely practicable, this research uniquely analyzes the shielding effectiveness of a variety of likely U.S. residential buildings from a realistic source term in a laboratory setting. Results produced in the investigation provide a comparison between theory and experiment behind building shielding factor methodology by applying laboratory measurements to detailed computational models. These models are used to develop a series of validated building shielding factors for generic residential housing units using the computational code MCNP5. For these building shielding factors to be useful in radiologic consequence assessments and emergency response planning, two types of shielding factors have been developed for; (1) the shielding effectiveness of each structure within a semi-infinite cloud of radioactive material, and (2) the shielding effectiveness of each structure from contaminant deposition on the roof and surrounding surfaces. For example, results from this investigation estimate the building shielding factors from a semi-infinite plume between comparable two-story models with a basement constructed with either brick-and-mortar or vinyl siding composing the exterior wall weather and a typical single-wide manufactured home with vinyl siding to be 0.36, 0.65, and 0.82 respectively. Graduation date: 2013 Thu, 11 Apr 2013 00:00:00 GMT http://hdl.handle.net/1957/38431 2013-04-11T00:00:00Z