Investigation of neutron source effects in subcritical media and application to a model of the MUSE-4 experiments

• Monte Carlo simulations have been performed to investigate the neutron sourceeffects in a sub-critical media successively coupled to a (d,d)-source, a (d,t)-source and aspallation source. The investigations have focused on the neutron energy spectra in thefuel and on the source relative efficiency j*. The calculations have been performed forthree sub-critical configurations, representative of the coming MUSE-4 experiments.The Monte Carlo codes MCNP and MCNPX have been used to compute j*. j*has been found to be low for the (d,d)-source (~1.35 compared to 1.0 for an averagefission neutron), while considerably higher for the (d,t)-source (~2.15) and the spallationsource (~2.35). The high value of j* for the spallation source has been shown to be dueto the fraction of high-energy neutrons (17 % of total source with En > 20 MeV) bornfrom spallation, which contribute for 50 % to the total number of fission neutronsproduced in the core. The variations of j* with neutron importance have also beenstudied for some spherical configurations with a (d,d)- and a (d,t)-source. For the class ofvariations considered here, j* was found to remain constant or increase only slightly inthe interval 0.70 < keff < 0.996.

Ämnesord

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

Nyckelord

MUSE-4

Neutron Source

Spallation

MCNP

MCNPX

Atomic physics

Atomfysik

Publikations- och innehållstyp

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