Development of the SCK CEN reference datasets for spent fuel safeguards research and development

A set of reference spent fuel libraries has been organized in datasets containing the material composition and radiation emission (i.e. neutrons and gamma-rays) of spent fuel. The data was obtained with computer simulations using the ORIGEN-ARP code, which is part of the SCALE 6.1 package.

Both fuel assembly geometries for Pressurized Water Reactors (PWR 17 × 17) and Boiling Water Reactors (BWR 8 × 8) are included in the datasets, and for each geometry both uranium oxide (UO₂) and mixed oxide (MOX) fuel materials are considered. The datasets contain the information for spent fuel with a broad range of initial enrichment (UO₂ fuel) or initial Pu content (MOX fuel), discharge burnup, and cooling time.

For each simulation the neutron spectra, divided into contributions from (α,n) reactions, spontaneous fission, and total neutron emission, as well as total gamma-ray spectra are included. The neutron emission from selected isotopes is also reported, divided in contributions from (α,n) reactions and spontaneous fissions.

The datasets are publicly available and are in a format that facilitates the further data extraction and processing for applications in the safeguards research & development related to spent fuel measurement and verification.

SUMCOR: Cascade summing correction for volumetric sources applying MCNP6

The main features of code SUMCOR developed for cascade summing correction for volumetric sources are described. MCNP6 is used to track histories starting from individual points inside the volumetric source, for each set of cascade transitions from the radionuclide. Total and FEP efficiencies are calculated for all gamma-rays and X-rays involved in the cascade. Cascade summing correction is based on the matrix formalism developed by Semkow et al. (1990). Results are presented applying the experimental data sent to the participants of two intercomparisons organized by the ICRM-GSWG and coordinated by Dr. Marie-Cristine Lépy from the Laboratoire National Henri Becquerel (LNE-LNHB), CEA, in 2008 and 2010, respectively and compared to the other participants in the intercomparisons.

Disintegration rate, gamma-ray emission probabilities and metastable half-life measurements of ⁶⁷Ga

The procedure for determining the (67)Ga disintegration rate by a primary method is described. The proposed triple 4πβ-γ coincidence system consists of a thin window gas-flow 4π proportional counter (PC) coupled to a NaI(Tl) scintillator and a HPGe crystal. Independent pulse height and occurrence time information is provided for the three detector outputs by means of a Software Coincidence System. Separate spectrometry measurements with a n-type reversed electrode coaxial Ge detector (REGe) were performed for obtaining gamma-ray emission probabilities per decay. Accurate values of disintegration rate, gamma-ray emission probabilities and the metastable half-life were achieved.