Dissolution experiments of commercial PWR (52 MWd/kgU) and BWR (53 MWd/kgU) spent nuclear fuel cladded segments in bicarbonate water under oxidizing conditions. Experimental determination of matrix and instant release fraction

Abstract

The denominated instant release fraction (IRF) is considered in performance assessment (PA) exercises to govern the dose that could arise from the repository. A conservative definition of IRF comprises the total inventory of radionuclides located in the gap, fractures, and the grain boundaries and, if present, in the high burn-up structure (HBS). The values calculated from this theoretical approach correspond to an upper limit that likely does not correspond to what it will be expected to be instantaneously released in the real system. Trying to ascertain this IRF from an experimental point of view, static leaching experiments have been carried out with two commercial UO2 spent nuclear fuels (SNF): one from a pressurized water reactor (PWR), labelled PWR, with an average burn-up (BU) of 52 MWd·kgU

An Automated SeaFAST ICP-DRC-MS Method for the Determination of 90Sr in Spent Nuclear Fuel Leachates

“…The overall uncertainty was obtained by identifying, quantifying and combining all individual contributions, mainly the 90 Sr standard reference solution (1.73%), sample and standard solutions weightings (0.054%), dilutions (0.072%), calibration (0.56%), and the sample repeatability (0.2% to 0.4%). The results on the spent nuclear fuel leachates are in good agreement with previously reported data in spent fuel leachates [3,12,13]. The fission 88 Sr/ 90 Sr ratio remained constant at 0.8 over the whole series of measurements showing good agreement with ORIGEN code calculations (ORIGEN-ARP, 2000) [26] and previous screening analysis [3,12,13].…”

“…The improvement of analytical procedures, involving an enhancement of selectivity emission. 90 Sr is an IRF radionuclide as it is faster released than the uranium fuel matrix [12,13]. Depending on the matrix composition of the sample, isobaric interferences by molecular or atomic ions can be expected at m/z 90 affecting the detection limit, accuracy and precision of the determination of 90 Sr by ICP-MS.…”

Instant release fraction corrosion studies of commercial UO 2 BWR spent nuclear fuel

“…The results obtained are slightly lower than the ones found in the literature for spent UO 2 fuels using carbonated solutions and similar experimental conditions [10,[17][18][19][20]. As discussed before, the effect of the interpellet space contribution on the total release could have played an important role, considering that all the segments found in the bibliography were cut including at least one dishing.…”

“…The results of this work were compared with data from experiments at similar conditions found in the literature [10,[17][18][19][20]. The comparisons for Cs, Rb and Sr are shown in the Figures 14, 15 and 16.…”

“…A previous work using a BWR fuel with similar irradiation conditions was performed by the same group [10]. In this case the fuel (53BWR) had a burn-up of 53GWd(t HM ) ) for caesium [10,[17][18][19][20]. )…”