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2026 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
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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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Latest News
Modernizing I&C for operations and maintenance, one phase at a time
The two reactors at Dominion Energy’s Surry plant are among the oldest in the U.S. nuclear fleet. Yet when the plant celebrated its 50th anniversary in 2023, staff could raise a toast to the future. Surry was one of the first plants to file a subsequent license renewal (SLR) application, and in May 2021, it became official: the plant was licensed to operate for a full 80 years, extending its reactors’ lifespans into 2052 and 2053.
Rei Kimura, Shohei Kanamura, Yuya Takahashi, Kazuhito Asano
Nuclear Technology | Volume 207 | Number 11 | November 2021 | Pages 1784-1792
Regular Technical Paper | doi.org/10.1080/00295450.2020.1843953
Articles are hosted by Taylor and Francis Online.
The small modular reactor (SMR) is considered one of the important energy sources for the realization of the de-carbonated society, especially SMR types that have 10 MW or less thermal power, called a microreactor or very small modular reactor (vSMR). Toshiba Energy Systems & Solutions has initiated the development of a multipurpose vSMR as a distributed energy source since 2017 called MoveluXTM (Mobile-Very-small reactor for Local Utility in X-mark).
In the current core design, a passive reactivity control device is required from the viewpoint of passive nuclear safety and operational cost reduction. The fundamental idea of vSMR passive reactivity control devices is based on the lithium expansion module (LEM) proposed by Kambe, et al. [“Startup Sequence of RAPID-L Fast Reactor for Lunar Base Power System,” Proc. Space Nuclear Conference, (2007)], however, the LEM has some issues regarding the lithium neutron absorber, such as production costs, chemical reactivity, and tritium generation. In the present study, the In-Gd alloy is proposed as an alternative to 6Li.
The In-Gd alloy is chemically stable in the air atmosphere; additionally, indium and gadolinium have enough neutron absorption cross section without isotope enrichment. However, the density, thermal expansion, and exothermal heat characteristics are not available, which is important information from the viewpoint of neutronics and safety. Hence, the material properties in the In-Gd alloy were measured, such as temperature-dependent density and chemical reactivity. Furthermore, control rod reactivity worth was evaluated based on the measured density.
As a result, the 1 wt% gadolinium contained in the In-Gd alloy shows control rod reactivity worth that is 2.5 times greater than natural lithium. Furthermore, the uncertainty of the In-Gd alloy density has a small impact on the reactivity worth; only in the range of 78 pcm (equivalent to 1% of insertion position) in the case of the 0.1 g/cm3 perturbation of the In-Gd alloy density. In conclusion, the present study shows the advantage and feasibility of the In-Gd alloy as a liquid neutron absorber for the Indium-Gadolinium Expansion Module.
