Since the 1950s, the nuclear energy industry has undergone continual, even if incremental, innovation and development. One of the greatest areas of research is nuclear fuel, especially fuel for the light water reactor (LWR) classes of boiling water reactors (BWRs) and pressurized water reactors (PWRs). From the start, BWR and PWR fuel technologies are designed with a negative moderator temperature coefficient to assure a self-limiting behavior during power excursion events. In this frame, BWR and PWR fuel has evolved over time, both in the materials that it is made of and how it is placed inside the core of the reactor, and optimizations have been pursued that enhance fuel performance and reliability. Although the packaging of BWRs and PWRs are quite different, similar materials and geometry optimization techniques have been used to improve performance in both types of reactors.

AREVA NP has been at the forefront of nuclear fuel development since the invention of LWR fuel and has designed a robust investigation to support the DOE’s EATF programme. Aligned with the strict requirements to achieve LTA readiness in 2022, AREVA NP has proposed a tiered system that can deploy Zirconium alloy fuel rods coated with Chromium (Cr) in LTAs in advance of the 2022 deadline.

Chromium coated Zirconium alloy cladding, developed by the CEA within the French Nuclear Institute (AREVA, CEA and EDF), and achieves added protection against high temperature oxidation in a severe accident. The protective Chromium coating gives control room operators additional time to return the plant to normal or shut down conditions before the onset of fuel damage. When paired with AREVA NP’s Cr2O3 pellet design, these fuel rods can retain fission gas better than standard UO2 and may provide additional steam and water resistance in the event of a fuel rod rupture. AREVA NP has also embarked on SiC/SiC composite cladding development within the French Nuclear Institute to further enhance accident tolerance.

Separately, the Electric Power Research Institute (EPRI) has partnered with AREVA Federal Services, a subsidiary of the US-based AREVA Inc, to develop a Molybdenum cladding that can resist extreme temperatures and especially maintain cool-able geometry in accident conditions.

View the full story at Nuclear Engineering International.