MHTGR fuel design and quality

The modular high-temperature gas-cooled reactor (MHTGR) has a top-level goal of safe, economical energy production. Occupational and site boundary irradiation exposure during normal and accident conditions is maintained well below established limits by multiple passive barriers to fission product release. The primary containment for fission products is the coated fuel particle, which consists of a microsphere of ceramic fuel encapsulated by an impervious, refractory coating. More than 1010 of these miniature pressure vessels are used in each MHTGR core. The design of the fissile fuel particle is shown. The design of coated particles and the quality achieved have improved significantly over the last two decades in both the United States and the FGR. In the United States the Fort St. Vrain HTGR fuel production set an early standard for quality. This standard was improved by a factor of 20x reduction in defects through the U.S. Department of Energy (DOE) development program for the earlier 2240-MW(thermal) HTGR and the current MHTGR. In the FRG the quality has improved from the Triso fuel made for the Arbeitsgemeinschaft Versuchsreaktor to current fuel for the gas-cooled reactor designs being developed there. The evolution in fuel quality coupled with the ongoing DOE-sponsored process development and fuel proof test program assures that the MHTGR design goal will be met