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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.
Lénárd Pál, Imre Pázsit
Nuclear Science and Engineering | Volume 155 | Number 3 | March 2007 | Pages 425-440
Technical Paper | Mathematics and Computation, Supercomputing, Reactor Physics and Nuclear and Biological Applications | doi.org/10.13182/NSE07-A2674
Articles are hosted by Taylor and Francis Online.
Neutron fluctuations in a constant multiplying medium (zero power noise) and those in a fluctuating medium (power reactor noise) have been traditionally considered as two separate disciplines that exist in two opposing limiting areas of operation (low and high power, respectively). They have also been treated by different mathematical methods, i.e., master equations and Langevin equation, respectively. In this paper we develop a theory of neutron fluctuations in a medium randomly varying in time, based on a forward-type master equation approach. This method accounts for both the zero power and the power reactor noise simultaneously. Factorial moments and related quantities (variance, power spectrum, etc.) of the number of the neutrons are calculated in subcritical systems with a stationary external source. It is shown that the pure zero power and power reactor noise results can be reconstructed in the cases of vanishing system fluctuations and high power, respectively, the latter being a nontrivial result. Further, it is shown that the effect of system fluctuations on the zero power noise is retained even in the limit of vanishing neutron number (reactor power). The results have thus even practical significance for low-power systems with fluctuating properties. The results also have a bearing on other types of branching processes such as evolution of biological systems, germ colonies, epidemics, etc., which take place in a time-varying environment.