### Abstract

Neutron streaming through the gap between a port plug and the port walls
will be a major contributor to the shutdown dose rate in ITER, and
calculating this streaming requires very effective variance reduction. The
article describes a way of estimating importances for a calculation of the
fast neutron flux, which will then generate weight windows. If necessary,
these can be refined iteratively. Once the fast neutron calculation works
well, the weight windows can be extended to lower energies and to photons
using appropriate factors for which some values are suggested here. Again,
these weight windows can be improved iteratively. Test runs in a simplified
geometry performed fairly well, though optimizing performance simultaneously
for the gamma flux at the end of the port and above it is difficult.

Original language | English |
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Pages (from-to) | 425-431 |

Journal | Annals of Nuclear Energy |

Volume | 35 |

Issue number | 3 |

DOIs | |

Publication status | Published - 2008 |

MoE publication type | A1 Journal article-refereed |

## Fingerprint Dive into the research topics of 'Application of importances or weight windows in MCNP4C to a geometry similar to an ITER equatorial port'. Together they form a unique fingerprint.

## Cite this

Wasastjerna, F. (2008). Application of importances or weight windows in MCNP4C to a geometry similar to an ITER equatorial port.

*Annals of Nuclear Energy*,*35*(3), 425-431. https://doi.org/10.1016/j.anucene.2007.07.011