HERA is part of the Second Framework for Irradiation Experiments (FIDES-II), a joint undertaking that allows FIDES-II members to benefit from a portfolio of irradiation facilities around the world.
FIDES-II members are Belgium, Czechia, Finland, France, Germany, Hungary, Japan, Korea, the Netherlands, Spain, Sweden, Switzerland, the United Kingdom, the United States, and the European Commission. The FIDES-II project period is 2024-2027.
The test: On May 14, Idaho National Laboratory staff working at the site’s Transient Reactor Test Facility (TREAT) conducted the first RIA transient test on a commercially irradiated fuel segment. This test was the first in the HERA project’s high-burnup test series.
The data from this and ensuing tests on this type of rod will provide information for new fuel designs that could extend the life of the current fleet of commercial reactors around the world, according to the article.
Early work: Prior to the high-burnup test series, HERA conducted six tests with fresh fuel samples, four of which took place at INL and two at the Nuclear Safety Research Reactor in Japan.
Most of the previous high-burnup RIA experiments were conducted on vintage cladding materials and tested at conditions that are slightly different than those expected in today’s LWRs, according to the article. “Modern cladding materials are expected to perform better under prototypic reactor conditions; however, the operation of UO2 fuel to higher burnups also presents new unknowns,” the newsletter noted. “The HERA tests will provide an opportunity to identify available cladding failure margins in modern claddings and identify any safety impacts from extending the burnup of UO2 fuels.”
Since the restart of operations at TREAT in 2017, an average of 20 fuel irradiation tests have been conducted each year. In each test, the fuel is exposed to highly controlled transient irradiations that can include short narrow bursts, simulating one of a variety of nuclear fuel accident scenarios. However, the test subjects irradiated previously are either fresh (unirradiated) fuel, or fuel that has already been irradiated in an INL test reactor. In contrast, the fuel inside TREAT for the HERA experiment was irradiated commercial fuel.
So far, five material test reactors, two transient test reactors, and one commercial reactor have performed irradiations for FIDES-II participants.
