As part of a study of VVER reactors a series of experimental assemblies with VVER like geometry were analysed. These experiments were carried out in Budapest. The experiments covered a range of lattice geometries, fuel enrichments, moderator densities(temperature) and boron content along with a range of poison loadings. The investigation compared measured and predicted reactivities of these different lattices.

AGR Fine Structure

A series of calculations have been carried out to investigate the variation of within cluster power for the fuel element used in the Advanced Gas Reactor in the UK. The analysis compared the prediction of radial and axial power variations with measurements.

The radial measurements were for a range of enrichments and covered both fresh and irradiated fuel. Comparisons were also made between the measured and predicted plutonium build up as a function of pin position.

The axial measurement compared the peak to mean axial power with measurement as a function of irradiation. These measurements were again carried out for a range of fuel enrichments.

MTR Transient

A WIMS/PANTHER analysis was carried out for a MTR core with heavy water moderation. The analysis looked at the predicton of core reactivity and rod worth. The main part of the analysis however was used to predict the transient behaviour of the reactor for a series of rod ejection transients.

Inventory Calculations

A survey was carried out for a range of PWR fuel types with different fuel enrichments and geometries. This study looked at the inventory of the fuel at discharge as a function of cluster type. The study used the link between WIMS and the inventory code FISPIN and used FISPIN to predict inventory and decay heat following depletion calculations using WIMS. This route ensured that the data used in FISPIN for the major nuclides was correctly adjusted for variations in the shielding and spectum.

Analysis of Gamma Heating Experiments

Experiments were carried out at Winfrith UK to study the gamma heating of graphite in a power reactor. These experiments were recently re-analysed using the latest version of WIMS and the latest gamma data library. The study used WIMS to compare prediction with measurement. Hence accurate estimates can be obtained of the gamma dose recieved by the graphite moderator in an AGR reactor.

Survey of Criticality of fuels in a Storage Pond

WIMS was used to carry out a survey of the criticality of a range of fuel clusters in a storage pond. The calculations were carried out to determine the most reactive fuel of the types that would be stored in the pond. The variations covered number of pins in the cluster, pin pitch, fuel radius and clan thickness. Tables were produced showing the variation of reactivity with these parameters.