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Organized to promote the advancement of knowledge in the use of nuclear science and technologies in the aerospace application. Specialized nuclear-based technologies and applications are needed to advance the state-of-the-art in aerospace design, engineering and operations to explore planetary bodies in our solar system and beyond, plus enhance the safety of air travel, especially high speed air travel. Areas of interest will include but are not limited to the creation of nuclear-based power and propulsion systems, multifunctional materials to protect humans and electronic components from atmospheric, space, and nuclear power system radiation, human factor strategies for the safety and reliable operation of nuclear power and propulsion plants by non-specialized personnel and more.
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ANS Standards Committee publishes joint ASME/ANS standard for Level 1/large early release frequency PRA
ANSI/ASME/ANS RA-S-1.1-2024, Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications, has been published by the American Nuclear Society. The document, which is a joint standard developed with the American Society of Mechanical Engineers by the ANS/ASME Joint Committee on Nuclear Risk Management, received the approval of the American National Standards Institute on February 29, 2024, and was issued on March 15, 2024.
Hajime Kabashima, Fumio Kasahara
Nuclear Technology | Volume 205 | Number 5 | May 2019 | Pages 694-707
Technical Paper | doi.org/10.1080/00295450.2018.1518556
Articles are hosted by Taylor and Francis Online.
Large-scale electric discharges events called high energy arcing faults (HEAF) have been reported in a nonnegligible number at nuclear power stations (NPSs) worldwide. If a HEAF occurs, the pressure and temperature in the electrical equipment rise rapidly, causing an explosive phenomenon with destructive force that results in serious damage to the equipment. In addition, a HEAF may cause a fire, which would have a serious impact on cables and other components in and around the equipment with the potential to disrupt power, instruments, and control in the plant.
In order to investigate the HEAF progression and to understand well the phenomena involved, the Regulatory Standard and Research Department in the Secretariat of the Nuclear Regulation Authority conducted a series of experiments (HEAF tests). High-energy electric arcs were generated at the facility simulating the design and operating conditions of the medium-voltage metalclad switchgears (M/Cs) at Unit 1 of the Onagawa NPS where the fire subsequently spread to multiple M/Cs via cable duct due to HEAF.
The test data have been obtained for the M/Cs on the threshold values of the arc energy that results in ensuing fires and on the characteristics of high-energy arcs.
On the basis of the knowledge obtained by the test results, measures for prevention of ensuing fire and mitigation of explosion are proposed as a new requirement for fire protection regulation of Japanese NPSs. Amendments to the regulatory requirements were issued on August 8, 2017 and enforced on the same day.
This paper summarizes the information on the high-energy arc characteristics and arc energies resulting in ensuing fires that was used as the basis of the new requirements and discusses the trend of arc power.