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Partial Defect Tester (PDET) This is a test.I plan to create an article on PDET.

PDET: Partial Defect Tester

Description and Principle: The methodology involves inserting tiny neutron and gamma detectors into the guide tubes of a spent fuel assembly and measuring the signals. The guide tubes form a quadrant symmetric pattern in the various PWR fuel product lines and the neutron and gamma signals from these various locations are processed to obtain a unique signature for an undisturbed fuel assembly. Signatures based on the neutron and gamma signals individually or in a combination are developed. Removal of fuel pins from the assembly causes the signatures to be visibly perturbed thus enabling the detection of diversion. The methodology has been proven to be effective in detecting as few as 10% missing pins in an assembly and without any fuel movement and operator provided information. In addition to the pin diversion detection capability, the data from PDET can be used to ensure that operator declared data are free from any falsification or fabrication. Thus the PDET can be the perfect and the only tool available for shipper/receiver verification of PWR spent fuel.

Capability: pin diversion detection of PWR spent fuel, facility declared data verification: Burn-up, cooling time and initial enrichment (initial enrichment is not calculated.)

Measurement Time: 3-5 min

Measurement Condition: underwater or in air (in air measurement changes sensitivity) Facility support required: a crane to move the PDET for visual insertion. Lowering of the PDET is achieved by gravity.