ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Division Spotlight
Thermal Hydraulics
The division provides a forum for focused technical dialogue on thermal hydraulic technology in the nuclear industry. Specifically, this will include heat transfer and fluid mechanics involved in the utilization of nuclear energy. It is intended to attract the highest quality of theoretical and experimental work to ANS, including research on basic phenomena and application to nuclear system design.
Meeting Spotlight
2024 ANS Winter Conference and Expo
November 17–21, 2024
Orlando, FL|Renaissance Orlando at SeaWorld
Standards Program
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!
Latest Magazine Issues
Aug 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
September 2024
Nuclear Technology
Fusion Science and Technology
August 2024
Latest News
Nuclear new build procurement considerations
It may seem counterintuitive, but the best time to enhance the ability to support operations and maintenance for a new plant is before construction starts. This is one of many lessons learned by the currently operating nuclear fleet. As construction and startup of many nuclear facilities was completed, it quickly became evident that the ability to efficiently support operations and maintenance was limited. Most of the information necessary to establish and manage procurement of spare and replacement items, maintenance, and configuration of the facilities was unavailable and had to be gathered on a case-by-case, “on-demand” basis. Absence of necessary information and the associated challenges resulted in the need for staff augmentation and multiyear-long projects to develop equipment bills of material and maintenance programs and to perform technical evaluations for the huge quantities of spare and replacement items being requested.
Hao-Ti Hsu, Ching-Han Chen, Chung-Kung Lo
Nuclear Technology | Volume 206 | Number 12 | December 2020 | Pages 1891-1908
Technical Paper | doi.org/10.1080/00295450.2020.1731404
Articles are hosted by Taylor and Francis Online.
As one of the lessons learned from the Fukushima Daiichi accident, long-term station blackout (SBO) and subsequent loss of ultimate heat sinks have prompted discussion on this topic in the nuclear industry. The SBO sequences for a Westinghouse three-loop pressurized water reactor (PWR) have been under investigation for a long period. To cope with the long-term SBO issue, many nuclear power plants have decided to replace the reactor coolant pump (RCP) seal by the new passive thermal shutdown seal (PSDS). The PSDS is a fail-safe protection device that will significantly reduce leakage from the RCP seal in case of loss of cooling. This makes a seal loss-of-coolant accident no longer a risk-significant event, and the relevant probabilistic risk assessment (PRA) models need to be modified to reflect the associated plant change. The PRA model of a Westinghouse PWR plant has been reviewed to reflect this more strongly; i.e. loss of component cooling water (CCW), loss of 4-kV vital alternating-current power, and loss of off-site power are revised for their sequences. According to the Westinghouse analysis, the PSDS temperature must be maintained below 104°C, and the operators have to control the RCP speed. In this paper, those factors are incorporated into the event tree structure revision of the loss of CCW event (TC) and loss of power either off-site (TP) or vital power A train (TAPB). In another case, LOOP initiating events need to consider the time span that the blackout conditions would affect the RCP seal integrity. Because the RCP will be tripped automatically, the limitation associated with RCP speed will not be applicable. Compared with the TC, TP, and TAPB event tree base cases, RCP speed slowdown or available time span is introduced into the PSDS model. The relevant part in the PRA model is subject to review and modification. The risk reduction associated with the PSDS is found to be significant.