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UIUC submits MMR construction permit application
The University of Illinois–Urbana-Champaign, in partnership with Nano Nuclear Energy, has submitted a construction permit application to the Nuclear Regulatory Commission for construction of a Kronos micro modular reactor (MMR). This is the first major step in the two-part 10 CFR Part 50 licensing process for the research and test reactor and is the culmination of years of technical refinement and regulatory alignment.
The team chose to engage with the NRC in a preapplication readiness assessment, providing the agency with draft versions of the majority of the CPA’s technical content for feedback, which is expected to ensure a high-quality application.
Rachel A. Shapiro, Massimiliano Fratoni
Nuclear Technology | Volume 194 | Number 1 | April 2016 | Pages 15-27
Technical Paper | doi.org/10.13182/NT15-97
Articles are hosted by Taylor and Francis Online.
Fully ceramic microencapsulated (FCM) fuel consists of TRISO (tristructural-isotropic) fuel particles embedded in a ceramic matrix (SiC) to form fuel pellets and rods and offers improved fission product retention and lower operating temperature with expected superior performance in normal and off-normal conditions compared to conventional fuel. When coupled with SiC cladding, FCM fuel eliminates zirconium altogether and is expected to drastically reduce hydrogen generation during a beyond-design-basis accident. In order to be deployed in current or future pressurized water reactors (PWRs), FCM fuel must meet or exceed the neutronic performance of conventional fuel. Limited by low heavy metal loading, an FCM fuel assembly requires increased enrichment and large fuel rods to match the cycle length of a conventional fuel assembly.
This study investigated the core design, neutronics, and thermal hydraulics of a PWR loaded with FCM fuel and sought to optimize the assembly design to minimize the enrichment required to reach fuel performance similar to that of conventional fuel. It was found that the implementation of FCM fuel in a 17 × 17 assembly requires close to 20% enrichment and large fuel rods. Such design performs comparably to conventional fuel (4.5% enrichment) in terms of cycle length, reactivity coefficients, intra-assembly power peaking factor, burnable poison penalty, and control rod worth but requires an increase of pumping power. A parametric analysis spanned a large design space varying fuel outer diameter and pitch-to-diameter ratio (P/D) and downselected two alternate assembly designs: 11 × 11 (1.65-cm outer diameter and 1.18 P/D) and 9 × 9 (2.12-cm outer diameter and 1.12 P/D). These designs meet the cycle length requirement with 18.6% and 16.2% enrichments, respectively, but feature a smaller minimum departure from nucleate boiling ratio (MDNBR) compared to a reference assembly. It was estimated that a slight increase in rod outer diameter increases MDNBR to the desired level and implies a pressure drop increase of 10%.
