Determination of the plutonium content in a spent fuel assembly by passive and active interrogation using a differential die-away instrument

Utilization of the Differential Die-Away Self-Interrogation Technique for Characterization and Verification of Spent Nuclear Fuel

“…indicated in Figure 5-12 should be considered with limitations, however the trend seems to be rather smooth raising the possibility of a straight forward calibration with more data. Comparing these trends to results in [33] it is worth noting that the results in this work trend consistently in a linear fashion while the previous results do not, as shown in Figure 5-12. However, the CT of 1 y that breaks the linear trend in the DDA results was not investigated in this work, therefore based on the range of CT investigated in both papers, it can still be concluded that the CT dependence of the fitting parameters of eq.…”

“…However the review was held in the rather early stages of the investigation of these techniques and their capabilities have since been proven that were not believed to be possible during the review. For example, it was assumed that DDA and DDSI could not determine total elemental plutonium content, but that his since proven to be incorrect [33,34]. and SINRD which were expected to be less expensive.…”

“…Applying the concepts developed through the DDA work [33], it can be shown that m Pu can be determined in simulation space using the DDSI instrument with a similarly high precision. The only quantities directly measurable by the DDSI instrument.…”

“…where a 1 , a 2 , and a 3 are the fitting (i.e., calibration) parameters. In the case of the DDSI instrument the singles rate (S) is identical to the passive neutron count rate used in [33], and through a simple relation with M it is then directly representative of the NE term in eq. (11):…”

“…It has been shown, by means of MCNP simulations, that total Pu content can be determined by DDA-and DDSI-based instruments [33,34] based on the known irradiation history of a given SFA, the total Pu content can be estimated through various burnup codes with an accuracy of 5%-10%. Such a large uncertainty may seem to be rather limiting; however, it should be noted that the NDA instrument used for Pu determination will likely use, for its own calibration, a calculated Pu content from a subset of the SFAs to be assayed.…”