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Safeguards Verification with Spent Nuclear Fuel Signatures

The safeguards goals and verification objectives present a challenge for safeguards inspectors.  Precise measurements of spent fuel isotopic content with destructive analysis (DA) will not be performed until the spent fuel is reprocessed.  Therefore, spent fuel safeguards rely on nuclear material accountancy and non-destructive analysis (NDA) methods based on the physical and radiation signatures of spent nuclear fuels.  Inspectors can use the spent fuel signatures we have already discussed to complete the verification objectives.

The starting point for IAEA verifications is the facility operator's report.  Ideally inspectors would be able to independently verify the spent fuel declarations in the operator's report solely with NDA based on spent fuel signatures.  However, as previously discussed, the spent fuel signatures available may depend on multiple spent fuel characteristics and cannot serve as an independent measure for all verifications.  In the cases where unique signatures do not exist for a quantity of interest, the spent fuel signatures available may be used to verify the consistency of the operator's report.  In this case, inspectors check to see if a measured signature is plausible given the values declared in the operator's report.  If the signature is inconsistent with the operator's report, then further investigation is needed.

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