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UCOR wins Top Workplace award
United Cleanup Oak Ridge (UCOR), the lead environmental cleanup contractor for the Department of Energy’s Oak Ridge Office of Environmental Management (OREM), has been named one of the Knoxville News Sentinel’s “Top Workplaces” in eastern Tennessee for 2022. The award is the result of a confidential, third-party survey of UCOR’s 2,000-member workforce by the Knoxville News Sentinel and the survey company Energage.
Jaeha Kim, Mohammad Abdul Motalab, Yonghee Kim, Gwangsoo Kim
Nuclear Technology | Volume 201 | Number 2 | February 2018 | Pages 138-154
Technical Paper | dx.doi.org/10.1080/00295450.2017.1415087
Articles are hosted by Taylor and Francis Online.
The power coefficient of reactivity (PCR) needs to be negative to achieve the inherent safety of a reactor. However, the possibility that the PCR of CANada Deuterium Uranium (CANDU) reactors can be positive has been raised in recent studies. In such circumstances, there was an experimental approach on evaluating the PCR of CANDU in 2012 at an in-operation CANDU reactor, Wolsong Unit 2. In the evaluation, the PCR was indirectly measured by a method that required estimating the reactivity variation due to Xe, liquid zone controllers (LZCs), and fuel depletion based on the measurement data. In this study, the PCR of a CANDU was reevaluated by the same methodology with more proper and detailed methods to estimate all the factors in addition to some minor reactivity corrections. The estimation of Xe and LZC reactivity was performed by an in-house three-dimensional code and Serpent2 in addition to RFSP-IST. Furthermore, several short studies regarding the factors that result in uncertainty of the Xe/LZC reactivity estimation were done in detail. First, a method to determine 14 LZC levels at a certain time based on the measurement data was appropriately selected through determining the features of the measurement data. The influence of the power transient scheme and the impact of local refueling transients due to daily refueling of CANDU reactors on xenon reactivity estimation were also analyzed briefly. Finally, the PCR of the CANDU in operational conditions was evaluated to be ~0.5 pcm/%P on average at a measurement time of 5 to 20 min after the power perturbation.