Feasibility of neutron coincidence counting for spent TRISO fuel

Ming Fang, Angela Di Fulvio

Research output: Contribution to journalArticlepeer-review


High-temperature gas reactors rely on TRIstructural-ISOtropic (TRISO) fuel for enhanced fission product retention. Accurate fuel characterization would improve monitoring of efficient fuel usage and accountability. We developed a new neutron multiplicity counter (NMC) based on boron coated straw (BCS) detectors and used it in coincidence mode for 235U assay in TRISO fuel. In this work, we demonstrate that a high-efficiency version of the NMC encompassing 396 straws is able to estimate the 235U in used TRISO-fueled pebbles or compacts with a relative uncertainty below 2.5% in 100 s. We performed neutronics and fuel depletion calculation of the HTR-10 pebble bed reactor to estimate the neutron and gamma-ray source strengths of used TRISO-fueled pebbles with burnup between 9 and 90 GWd/t. Then, we measured a gamma-ray intrinsic efficiency of 10−12 at an exposure rate of 340.87 R/h. The low gamma-ray sensitivity and high neutron detection efficiency enable the inspection of used fuel.

Original languageEnglish (US)
Article number110062
JournalAnnals of Nuclear Energy
StatePublished - Dec 1 2023
Externally publishedYes


  • Boron coated straw
  • HTR-10
  • Neutron coincidence counting
  • Neutron multiplicity counter
  • PBR

ASJC Scopus subject areas

  • Nuclear Energy and Engineering


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