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Fission of very heavy nuclei is a traditional source of
neutron-rich isotopes. The energy released during the
neutron-induced fission of nuclear fuels is used for energy
production in power reactors. The process of beta-n emission
from fission products contributes to the total number of
neutrons inducing fission process in nuclear fuel.
The uncertainties in beta-delayed neutron data may result
in undesirable conservatism in the design and operation of nuclear
reactor control systems [1].
Therefore, reliable and accurate data on the individual βn-precursors
produced in nuclear fuels are needed. In 1990, an international
working group was formed under the auspices of the Nuclear Energy
Agency (NEA) Working Party on International Evaluation Cooperation (WPEC),
as a Subgroup 6 (SG6), to review, improve and validate β-delayed
neutron data [1].
The activities of the SG6 were terminated in 1999, but the interest in
β-delayed neutron data is far from being terminated.
In particular, new trends in reactor technologies (Advanced Fuel Cycle,
Hybrid Accelerator-Reactor systems) are requiring verification of the
available data as well as new measurements. Among other important
parameters for modelling the processes inside the reactors are
β half-lives of fission products and their daughter activities
and so called Total Decay Heat released during the decay of
neutron-rich products.
The β-delayed neutron emission from neutron-rich nuclei
also re-fuels nucleosynthesis during SuperNova events providing
more neutrons to be captured and changing the isobaric distribution
of the ashes created in the rapid-neutron capture process (r-process).
Topics
References
[1] D'Angelo, Progress in Nucl. Energy, Vol. 41, 1, 2002.
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