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Science and Technology of Nuclear Installations
Volume 2012, Article ID 376164, 1 page

Advanced Computational Models for Accelerator-Driven Systems

1Argonne National Laboratory, Chicago, IL, USA
2Politecnico di Torino, Turin, Italy
3Royal Institute of Technology (KTH), Stockholm, Sweden

Received 17 May 2012; Accepted 17 May 2012

Copyright © 2012 Alberto Talamo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

In the nuclear engineering scientific community, Accelerator Driven Systems (ADSs) have been proposed and investigated for the transmutation of nuclear waste, especially plutonium and minor actinides. These fuels have a quite low effective delayed neutron fraction relative to uranium fuel, therefore the subcriticality of the core offers a unique safety feature with respect to critical reactors. The intrinsic safety of ADS allows the elimination of the operational control rods, hence the reactivity excess during burnup can be managed by the intensity of the proton beam, fuel shuffling, and eventually by burnable poisons. However, the intrinsic safety of a subcritical system does not guarantee that ADSs are immune from severe accidents (core melting), since the decay heat of an ADS is very similar to the one of a critical system. Normally, ADSs operate with an effective multiplication factor between 0.98 and 0.92, which means that the spallation neutron source contributes little to the neutron population. In addition, for 1 GeV incident protons and lead-bismuth target, about 50% of the spallation neutrons has energy below 1 MeV and only 15% of spallation neutrons has energies above 3 MeV. In the light of these remarks, the transmutation performances of ADS are very close to those of critical reactors.

This contributes to different research topics, including the following:(i)analyses of subcritical research assemblies:(a)the analytical solution of the P1 neutron transport equation without the space-time separation;(b)the comparison between numerical and experimental results;(c)the investigation of the kinetic and local neutron parameters;(d)the neutron detector dead time;(e)the two-group theory of the Feynman-alpha method;(ii)fuel cycles for actinides incineration and 233U production from thorium;(iii) new computational software to analyze the in-core and out-of-core fuel cycles, the activation of structural materials, and the accumulation of spallation products; (iv)safety studies and the design of the SCRAM system;(v) studies on nuclear level density parameters of target isotopes, energy correlation of spallation neutrons, and fragments production.

Alberto Talamo
Piero Ravetto
Waclaw Gudowski