Model of a fission counter system for optimizing performance at high gamma dose rates. [LMFBR]
A mathematical model has been developed for predicting the ability of a fission counter to operate at a high gamma dose rate. There are several potential applications in reactor programs for detectors that can accurately measure neutron fluxes in the range 0.1 to 1.0 nv(th) while subjected to gamma dose rates of 10/sup 4/ to more than 10/sup 6/ R/hr. Fission counters for such service have up to now been designed on the basis of laborious testing of prototypes combined with extrapolation from existing designs. The objective of this work is to make it possible to arrive at an optimum design without expensive testing. In this model, the complete system of counter, cables, preamplifier, main amplifier, filters, and discriminator is considered, including the effects of interaction of counter capacitance with cable and preamplifier impedance. Electrical noise theory is used to calculate the frequency spectrum of the interfering signal generated by pileup of gamma pulses, to add to it a contribution from electronic noise, and to obtain the rate at which the total noise signal triggers the discriminator. The shapes and widths of neutron and gamma pulses are calculated from the electron drift velocity and electrode spacing.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6482713
- Report Number(s):
- ORNL/TM-6408; TRN: 79-003182
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
FISSION CHAMBERS
SPECIFICATIONS
LMFBR TYPE REACTORS
REACTOR INSTRUMENTATION
NEUTRON DETECTION
PERFORMANCE
BREEDER REACTORS
DETECTION
EPITHERMAL REACTORS
FAST REACTORS
FBR TYPE REACTORS
IONIZATION CHAMBERS
LIQUID METAL COOLED REACTORS
MEASURING INSTRUMENTS
NEUTRON DETECTORS
RADIATION DETECTION
RADIATION DETECTORS
REACTORS
440101* - Radiation Instrumentation- General Detectors or Monitors & Radiometric Instruments
210500 - Power Reactors
Breeding