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.
Explore membership for yourself or for your organization.
Conference Spotlight
2026 Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
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
Dec 2025
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
January 2026
Nuclear Technology
December 2025
Fusion Science and Technology
November 2025
Latest News
What’s the most difficult question you’ve been asked as a maintenance instructor?
Blye Widmar
"Where are the prints?!"
This was the final question in an onslaught of verbal feedback, comments, and critiques I received from my students back in 2019. I had two years of instructor experience and was teaching a class that had been meticulously rehearsed in preparation for an accreditation visit. I knew the training material well and transferred that knowledge effectively enough for all the students to pass the class. As we wrapped up, I asked the students how they felt about my first big system-level class, and they did not hold back.
“Why was the exam from memory when we don’t work from memory in the plant?” “Why didn’t we refer to the vendor documents?” “Why didn’t we practice more on the mock-up?” And so on.
Pierre Saunier (CEA), Franck Peysson, Denis Etienne (BOUYGUES Construction), Vincent Le Talbodec, Laurent Dufrene (CNIM)
Proceedings | 2018 International Congress on Advances in Nuclear Power Plants (ICAPP 2018) | Charlotte, NC, April 8-11, 2018 | Pages 667-674
The French Generation IV sodium cooled Fast Reactor (SFR) is designed with a large pool-type vessel and equipment (pumps, heat decay removal) which are sensitive to horizontal seismic accelerations. It is necessary to design these components with an appropriate seismic isolation system depending on the site seismic conditions.
For ASTRID, the SFR industrial demonstrator project under development by the CEA, the preliminary study has concluded to the necessity to isolate horizontally all the buildings of the nuclear island on a para-seismic raft equipped with seismic pads. At the current Basic Design phase, the project takes into account the lessons learnt from the recent Jules Horowitz Reactor (JHR) and ITER research reactor projects under construction and equipped with seismic isolators.
Seismic isolation allows to decrease the horizontal building accelerations from 5 to 10 times. Positive aspects consist in reducing the average reinforcement ratio of these buildings and to ease the design of the main reactor block components, with in the end, an expected gain of cost.
ASTRID partners aims also to improve and innovate with this isolation technology. Based on the European standards, previous solutions used elastomeric rubber with metallic parts pads. BOUYGUES Company (CEA’s partner for ASTRID), associated to CNIM Company, has chosen to change the raw material, using polyurethane material instead of natural rubber. Several advantages are expected. With ageing, the polyurethane is softening whereas natural rubber is hardening (and potentially reducing seismic isolation capacity).
The main conclusion is that these new pads respect the dynamic behavior of the buildings, give better margin in seismic condition and allow modifying easily the pads stiffness.
The next step is that a complete qualification program will be implemented in order to validate the one scale dynamic characteristics of the isolators at full scale and to justify the requested 90 years lifetime.
