Rudolf E. Slovacek

Spent-fuel assay performance and Monte Carlo analysis of the Rensselaer slowing-down-time spectrometer

The slowing-down-time method for the nondestructive assay of light water reactor (LWR) spent fuel is under development at Rensselaer Polytechnic Institute. A series of assay measurements of an LWR fuel assembly replica were carried out at the Rensselaer lead slowing-down-time spectrometer facility by using [sup 238]U and [sup 232]Th threshold fission detectors and [sup 235]U and [sup 239]Pu probe chambers. An assay model relating the assay signal and the signals of the probe chambers to the unknown masses of the fissile isotopes in the fuel assembly was developed. The probe chamber data were used to provide individual fission counting spectra of [sup 235]U and [sup 239]Pu inside the fuel assembly and to simulate spent-fuel assay signals. The fissile isotopic contents of the fuel were determined to better than 1%. Monte Carlo analyses were performed to simulate the experimental measurements, determine certain parameters of the assay system, and investigate the effect of the fuel assembly and hydrogen impurities on the performance of the system. The broadened resolution of the system caused by the presence of the fuel was still found to be sufficient for the accurate and separate assay of the uranium and plutonium fissiles in spent fuel.

Intermediate structure in the fission cross sections of the even curium isotopes

Abstract The neutron-induced fission cross sections of Cm-244, Cm-246, and Cm-248 which were measured with the RINS lead spectrometer system at RPI have been analyzed for intermediate structure. Gross structure is observed in Cm-244 near 200, 400, 800, and 2000 eV and in Cm-246 near 350, 800, and 3300 eV. For Cm-248 a very broad type of structure is observed near 10 keV. Assuming double-barrier fission, the Cm-244 and Cm-246 structure is consistent with the outer potential well lying 2 to 3 MeV above the inner potential well. The broad structure observed in Cm-248 fission implies significantly different barrier parameters than for Cm-244 or Cm-246.