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Human Factors, Instrumentation & Controls
Improving task performance, system reliability, system and personnel safety, efficiency, and effectiveness are the division's main objectives. Its major areas of interest include task design, procedures, training, instrument and control layout and placement, stress control, anthropometrics, psychological input, and motivation.
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2025 ANS Annual Conference
June 15–18, 2025
Chicago, IL|Chicago Marriott Downtown
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The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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High-temperature plumbing and advanced reactors
The use of nuclear fission power and its role in impacting climate change is hotly debated. Fission advocates argue that short-term solutions would involve the rapid deployment of Gen III+ nuclear reactors, like Vogtle-3 and -4, while long-term climate change impact would rely on the creation and implementation of Gen IV reactors, “inherently safe” reactors that use passive laws of physics and chemistry rather than active controls such as valves and pumps to operate safely. While Gen IV reactors vary in many ways, one thing unites nearly all of them: the use of exotic, high-temperature coolants. These fluids, like molten salts and liquid metals, can enable reactor engineers to design much safer nuclear reactors—ultimately because the boiling point of each fluid is extremely high. Fluids that remain liquid over large temperature ranges can provide good heat transfer through many demanding conditions, all with minimal pressurization. Although the most apparent use for these fluids is advanced fission power, they have the potential to be applied to other power generation sources such as fusion, thermal storage, solar, or high-temperature process heat.1–3
Po-Jung Chiu, Chung-Kung Lo, Tai-Hung Wu
Nuclear Technology | Volume 209 | Number 1 | January 2023 | Pages 53-68
Technical Paper | doi.org/10.1080/00295450.2022.2105633
Articles are hosted by Taylor and Francis Online.
We discuss the specific risk significance in the extended pre-defueled (PD) phase of the decommissioning process, particularly if spent fuels are still in the core due to the low-power and shutdown refueling plant operating state (POS). The issue of full-core discharge capability after permanent shutdown during the PD phase motivated this study on the evolution of system risks using a reference plant design of the two-unit/BWR-4/Mark-I.
The effects of the reactor core and the spent fuel pool (SFP) on the incorporative risks are explored. The probabilistic risk assessment methodology, including the technical elements, is systematically developed by defining two primary configurations from the internal event analysis under the models 30, 60, 180, 365, and 942 days after permanent shutdown, respectively. The movable refueling gate between the reactor core and the SFP, as well as the residual heat removal (RHR) system, have been subjected to two sensitivity studies on system configurations in order to examine the induced impacts by the refueling gate and cooling systems. MELCOR, a realistic thermal-hydraulic code, is utilized to determine the decay heat levels and the success criteria after shutdown. The two operator tasks are assumed to be independent in the situation of decreasing decay heat after shutdown and a long time available for human actions.
In addition, the WinNUPRA software package is used for the fuel uncovery sequence quantification. Plant-centered loss-of-offsite power (LOOP), flow diversion loss-of-coolant accidents (LOCAs) to the suppression pool via the RHR system, switchyard-centered LOOPs, and LOCAs in the connected systems via the RHR, have proven to be the most significant initiating events for the configurations. When compared to the low-power and shutdown refueling POS, the realistic quantification results in terms of fuel uncovery frequencies and the evolution of the risk profile for the basic and sensitivity configurations meet the expectations under the PD-phase condition of low-decay heat levels.
