The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

The DD Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Uranium Neutron Coincidence Collar

“…The simulated assay responses for the MP320 and the nGen-310 generators are very similar to that obtained from the Am(Li) isotopic sources in terms of systematic bias; however, the measurement precision from the Am(Li)-based analysis is superior to that obtainable from the neutron generators. Unlike the DD/AWCC system [1], the large physical size of the generator tube does not appear to be the limiting factor. To illustrate this point, the above series of simulations were performed for an idealized, compact DD neutron generator of the same total volume as the Am(Li) source tungsten shield (Figure 6).…”

“…From the DD/AWCC study [1] previously completed we saw that delayed neutron counting with operation of the neutron generators in pulsed mode provided improved measurement precision relative to the active coincidence counting approach. Because the simulated results of the DD/UNCL system indicated that the active coincidence counting method would result in degradation of the measurement precision, the potential for delayed neutron counting was investigated for the assay of the fresh fuel assemblies.…”

“…Previously we examined the performance of Oak Ridge National Laboratory's (ORNL's) Large Volume Active Well Coincidence Counter (LV-AWCC) modified to accept a commercially available deuteriumdeuterium (DD) neutron generator to examine the potential of the DD neutron generator as an alternative to the isotopic sources [1]. That work indicated that the DD generator was a viable replacement for the AWCC applications, but because of the large dimensions of that generator, the DD/AWCC would have to be run as delayed neutron counting system to provide equivalent measurement precision.…”

The D-D Neutron Generator as an Alternative to Am(Li) Isotopic Neutron Source in the Active Well Coincidence Counter

“…In this case, the flux monitor is a single 8 in. active length, 1 atm partial pressure 3 He tube mounted in the HDPE shield below the AWCC. The output of the flux monitor is read using the shift register AUX scaler input.…”

“…Over the course of 2 months of measurements we observed that the neutron output tended to fluctuate about ±0.5% over the course of a day. To correct for the variation in neutron yield, a single, short, low pressure 3 He tube was installed into the HDPE shield surrounding the neutron generator to monitor and correct for these variations. All active coincidence measurements will be corrected based on the ratio of the measured flux monitor relative to an essentially arbitrary reference rate of 460 cps (although, 460 cps was the first measured flux monitor rate for the chosen beam current and HV settings).…”