Production irradiated fuel assay gauge neutron detection: description and testing (LWBR Development Program)

Technical Report · Tue Apr 01 04:00:00 EST 1986

OSTI ID:5764491

Tessler, G

The production irradiated fuel assay gauge (PIFAG) is being used to nondestructively assay irradiated LWBR core fuel rods by the method of active neutron interrogation with delayed neutron counting. Twenty delayed neutron detectors have been assembled, fifteen for use in the PIFAG and five spares. A delayed neutron detector assembly consists of four /sup 10/B-lined proportional counters connected in parallel to a common preamplifier. The preamplifier utilizes an LD604 hybrid circuit and is located within the detector assembly. An extensive test program has been carried out to measure detector properties and performance. The properties investigated include the sensitivity of delayed neutron detectors' count rate to small changes in applied bias, small angle rotation of the detector assembly about its axis, temperature of the preamplifier, temperature of the /sup 10/B-lined proportional counters, temperature of the polyethylene medium containing the detectors and the /sup 238/PuBe source used for detector testing, and small changes in applied preamplifier threshold voltage. Twelve miniature fission counters, four for the PIFAG and eight spares, have been procured to measure interrogation source neutrons close to the surface of a fuel rod as the rod passes through the PIFAG source region. These counters are sensitive to the materials in the fuel rod and provide a measure of the axial distribution of fuel in the rod. Fission counter testing was limited by low count rates. Sufficient data were obtained, however, to show that all detectors and electronics perform satisfactorily. 30 figs., 11 tabs.

• Research Organization: Bettis Atomic Power Lab., West Mifflin, PA (USA)
• DOE Contract Number: AC11-76PN00014
• OSTI ID: 5764491
• Report Number(s): WAPD-TM-1547; ON: DE86010643
• Country of Publication: United States
• Language: English

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