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Aerospace Nuclear Science & Technology
Organized to promote the advancement of knowledge in the use of nuclear science and technologies in the aerospace application. Specialized nuclear-based technologies and applications are needed to advance the state-of-the-art in aerospace design, engineering and operations to explore planetary bodies in our solar system and beyond, plus enhance the safety of air travel, especially high speed air travel. Areas of interest will include but are not limited to the creation of nuclear-based power and propulsion systems, multifunctional materials to protect humans and electronic components from atmospheric, space, and nuclear power system radiation, human factor strategies for the safety and reliable operation of nuclear power and propulsion plants by non-specialized personnel and more.
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Glass strategy: Hanford’s enhanced waste glass program
The mission of the Department of Energy’s Office of River Protection (ORP) is to complete the safe cleanup of waste resulting from decades of nuclear weapons development. One of the most technologically challenging responsibilities is the safe disposition of approximately 56 million gallons of radioactive waste historically stored in 177 tanks at the Hanford Site in Washington state.
ORP has a clear incentive to reduce the overall mission duration and cost. One pathway is to develop and deploy innovative technical solutions that can advance baseline flow sheets toward higher efficiency operations while reducing identified risks without compromising safety. Vitrification is the baseline process that will convert both high-level and low-level radioactive waste at Hanford into a stable glass waste form for long-term storage and disposal.
Although vitrification is a mature technology, there are key areas where technology can further reduce operational risks, advance baseline processes to maximize waste throughput, and provide the underpinning to enhance operational flexibility; all steps in reducing mission duration and cost.
Kazuki Kuwagaki, Jun Nishiyama, Toru Obara
Nuclear Science and Engineering | Volume 191 | Number 2 | August 2018 | Pages 178-186
Technical Note | doi.org/10.1080/00295639.2018.1463744
Articles are hosted by Taylor and Francis Online.
In the breed and burn (B&B) strategy, low-reactivity fuels are loaded in a core. It is difficult to keep criticality in operating a small core. To enhance the potential for achieving criticality, the neutron economy in a core should be improved. One improvement method is to increase the core size and reduce neutron leakage. If it is necessary to avoid the large-sized core, another method is to locate high-reactivity fuels in high-neutron-importance region continuously through an equilibrium burnup state. On the other hand, to stabilize the change of neutron flux and power distribution during the operation, the B&B regions need to be kept stationary in the same region.
In this study, a rotational fuel-shuffling concept was proposed. In this concept, fuel assemblies are moved to the next position step by step in a divided symmetry core region. Fresh fuel is loaded from the periphery and moved toward the center region, then moved outward and discharged. If the core could achieve an equilibrium state at which high-reactivity fuels are continuously placed in the core center region, it would be possible to keep the B&B regions stationary. In this kind of equilibrium state, high-reactivity fuels are placed in high-neutron-importance region stably. Simulations for this concept were performed using the continuous-energy Monte Carlo code MVP/MVP-BURN. A small lead-bismuth-cooled fast reactor with metallic fuel was adopted as the core design. As a result, a core with rotational fuel shuffling achieved an equilibrium cycle at criticality, and the change of multiplication factors in the equilibrium cycle was less than 0.1%. The neutron flux and power distributions were almost unchanged during the operation. In addition, high-reactivity fuels were constantly placed in the high-neutron-flux region. It was found that this concept can achieve criticality and a stable power profile.