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**Harvard**

Larsson, V. och Demazière, C. (2009) *Comparative study of 2-group P1 and diffusion theories for the calculation of the neutron noise in 1D 2-region systems*.

** BibTeX **

@article{

Larsson2009,

author={Larsson, Viktor and Demazière, Christophe},

title={Comparative study of 2-group P1 and diffusion theories for the calculation of the neutron noise in 1D 2-region systems},

journal={Annals of Nuclear Energy},

issn={0306-4549},

volume={36},

issue={10},

pages={1574-1587},

abstract={In this paper, the neutron noise, i.e. the stationary fluctuations of the neutron flux around its mean
value, is calculated in 2-group P1 and diffusion theories for a 2-region slab reactor using Green’s
function technique. The applicability of diffusion theory for different types and locations of the perturbation,
as well as different frequencies, is assessed. Material data, i.e. nuclear cross-sections and kinetic
parameters, representative of a Light Water Reactor (LWR) and of a Heavy Water Reactor (HWR),
respectively, are used in this work. It is demonstrated that for practical situations in LWRs and HWRs,
there is no significant advantage to use P1 theory since diffusion theory gives acceptable results. The
largest deviations between the two formalisms are observed in regions of large gradients of the static
neutron flux, such as close to the reflector interface and close to the perturbation. Such observations
are in agreement with theoretical expectations. This study also indicates that neglecting the effect of
cross-section perturbation on the diffusion coefficient gives a rather small impact on the solution. This
allows drastically simplifying the determination of the neutron noise. When using numerical
techniques for such a determination the memory requirements and computational effort can be significantly
reduced.},

year={2009},

}

** RefWorks **

RT Journal Article

SR Electronic

ID 98763

A1 Larsson, Viktor

A1 Demazière, Christophe

T1 Comparative study of 2-group P1 and diffusion theories for the calculation of the neutron noise in 1D 2-region systems

YR 2009

JF Annals of Nuclear Energy

SN 0306-4549

VO 36

IS 10

SP 1574

OP 1587

AB In this paper, the neutron noise, i.e. the stationary fluctuations of the neutron flux around its mean
value, is calculated in 2-group P1 and diffusion theories for a 2-region slab reactor using Green’s
function technique. The applicability of diffusion theory for different types and locations of the perturbation,
as well as different frequencies, is assessed. Material data, i.e. nuclear cross-sections and kinetic
parameters, representative of a Light Water Reactor (LWR) and of a Heavy Water Reactor (HWR),
respectively, are used in this work. It is demonstrated that for practical situations in LWRs and HWRs,
there is no significant advantage to use P1 theory since diffusion theory gives acceptable results. The
largest deviations between the two formalisms are observed in regions of large gradients of the static
neutron flux, such as close to the reflector interface and close to the perturbation. Such observations
are in agreement with theoretical expectations. This study also indicates that neglecting the effect of
cross-section perturbation on the diffusion coefficient gives a rather small impact on the solution. This
allows drastically simplifying the determination of the neutron noise. When using numerical
techniques for such a determination the memory requirements and computational effort can be significantly
reduced.

LA eng

DO 10.1016/j.anucene.2009.07.009

LK http://dx.doi.org/10.1016/j.anucene.2009.07.009

OL 30