Original scientific paper
Assessment of the Photon and Neutron Source Term for the NPP Krško Spent Fuel
Marjan Kromar
orcid.org/0000-0001-8960-203X
; “Jožef Stefan” Institute Reactor Physics Division Jamova 39, 1001 Ljubljana, Slovenia and University of Maribor Faculty of Energy Technology Hočevarjev trg 1, 8270 Krško, Slovenia
Bojan Kurinčič
; Nuclear Power Plant Krško Engineering Division - Nuclear Fuel & Reactor Core Vrbina 12, 8270 Krško, Slovenia
Abstract
Accurate knowledge of the fuel nuclide inventory is important after reactor shut down, during
the fuel storage and subsequent reprocessing or disposal to provide adequate shielding from the
photon and neutron radiation. In this paper possibility to calculate the NPP Krško photon and
neutron source term with the Serpent code has been analysed. Some deficiencies in the supplied
ENDF/B-VII.0 decay library have been observed. In addition, Serpent reports only spontaneous
fission rates without (α, n) and (β, n) contributions. To get neutron emission, spontaneous fission
rates had to be multiplied with the average number of neutrons born for each particular nuclide
manually. Comparison with the Origen code has shown acceptable agreement of the ENDF/B-VII.1
results. Influence of several factors such as fuel burnup, enrichment, temperature, moderator
temperature (density), soluble boron concentration, average power, and burnable absorbers has been
analysed. In addition, it was demonstrated that, except for the burnup and enrichment, averaging of
all other parameters is acceptable approach. IFBA fuel should be accounted for explicitly due to
relative high impact on the photon and neutron emissions.
Keywords
PWR fuel, photon source term, neutron source term
Hrčak ID:
247100
URI
Publication date:
28.10.2019.
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