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Nuclear Safeguards Education Portal

Spent fuel coincident counter (SFCC)

The spent fuel coincident counter (SFCC) is an underwater neutron coincident counter for the verification of operator declared plutonium content in canned fast breeder reactor spent fuel. A single ionization chamber measures the γ ray dose from the spent fuel to determine the appropriate operational parameters to avoid γ ray pile effects in the 3 He tubes. The plutonium isotopics are calculated based on a validated burnup chains code. Specially developed iterative software in combination with Monte Carlo N particle transport code (MCNP) modelling converts the measured single and double neutron count rates to plutonium mass. The SFCC easily distinguishes irradiated fuel from non-fuel items which are loaded into the reactor to replace discharged assemblies.

(Source: IAEA Safeguards Techniques and Equipment)