Optimization of the Spent Fuel Attribute Tester using radiation transport calculations
- Sandia National Labs., Albuquerque, NM (United States)
- International Atomic Energy Agency, Vienna (Austria). Dept. of Safeguards
The International Atomic Energy Agency uses the Spent Fuel Attribute Tester (SFAT) to measure gamma signatures from fuel assemblies stored in spent fuel pools. It consists of a shielded, collimated NaI(Tl) detector attached to an air-filled pipe. The purpose of the present study was to define design changes, within operational constraints, that would improve the target assembly {sup 137}Cs signal relative to the background signals from adjacent assemblies. This improvement is essential to reducing to an acceptable level the measurement time during an inspection. Monte Carlo calculations of the entire geometry were impractical; therefore, a hybrid method was developed that combined one-dimensional discrete ordinates models of the spent fuel pool, three-dimensional Monte Carlo calculations of the SFAT, and detector response calculations. The method compared well with measurements taken with the existing baseline SFAT. Calculations predicted significant improvements in signal-to-noise ratio. Recommended changes included shortening the pipe and increasing its wall thickness, placing low-Z filters in the crystal line of sight, reducing the thickness of shielding around the collimator aperture and adding shielding around the crystal, and reducing the diameter of the crystal. An instrument incorporating these design changes is being fabricated in Finland and will be tested this year.
- OSTI ID:
- 61466
- Report Number(s):
- CONF-930749--
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
BWR TYPE REACTORS
CALCULATION METHODS
CESIUM 137
DESIGN
EXPERIMENTAL DATA
FUEL STORAGE POOLS
GAMMA DETECTION
MATHEMATICAL MODELS
MODIFICATIONS
NAI DETECTORS
PERFORMANCE
RADIOMETRIC ANALYSIS
RECOMMENDATIONS
SOURCE TERMS
SPENT FUEL ELEMENTS
SPENT FUELS