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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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INL makes a case for eliminating ALARA and setting higher dose limits
A report just released by Idaho National Laboratory reviews decades of radiation protection standards and research on the health effects of low-dose radiation and recommends that the current U.S. annual occupational dose limit of 5,000 mrem be maintained without applying ALARA—the “as low as reasonably achievable” regulatory concept first introduced in 1971—below that threshold.
Noting that epidemiological studies “have consistently failed to demonstrate statistically significant health effects at doses below 10,000 mrem delivered at low dose rates,” the report also recommends “future consideration of increasing this limit to 10,000 mrem/year with appropriate cumulative-dose constraints.”
Ang Zhu, Yunlin Xu, Thomas Downar
Nuclear Science and Engineering | Volume 182 | Number 4 | April 2016 | Pages 435-451
Technical Paper | doi.org/10.13182/NSE15-39
Articles are hosted by Taylor and Francis Online.
Three-dimensional (3D), full-core transport modeling with pin-resolved detail for reactor dynamic simulation is important for some multiphysics reactor applications. However, it can be computationally intensive due to the difficulty in maintaining accuracy while minimizing the number of time steps. An innovative Predictor-Corrector Quasi-static Method (PCQM) is introduced that is based on a Transient MultiLevel (TML) methodology. Two levels of couplings are used between 3D-transport/3D-CMFD (coarse-mesh finite difference) and 3D-CMFD/EPKE (exact point-kinetics equation). In each level, the original flux equation is solved in the coarse predictor step and then is factorized as an amplitude and a shape function in the corrector step, where the predicted solution is adjusted using multiple fine steps. In the first-level 3D-transport/3D-CMFD coupling, the angular and subpin flux shape functions in the Boltzmann transport equation are assumed to vary slowly over time, and the CMFD cellwise amplitude function is solved using multiple steps by the 3D-CMFD transient equation. In the second level, the CMFD scalar flux calculated in the last step is further corrected by a whole-core-wise amplitude function generated by the EPKE solver. The utilization of hierarchical multilevel neutronics transient solvers achieves the goal to balance the numerical accuracy and computational efficiency. In addition, a new iteration scheme with pin-resolve thermal-hydraulic feedback and theoretical proof for the accuracy of PCQM are also presented. Finally, a stripe assembly case adopted from the SPERT (Special Power Excursion Reactor Test) transient tests is used to demonstrate the accuracy and efficiency of the TML method.