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The development of a fuel lifecycle reactivity control strategy for a generic micro high temperature reactor

  • Received : 2023.05.12
  • Accepted : 2023.07.18
  • Published : 2024.03.25

Abstract

This article provides an overview of the design methodology used to develop a conceptual set of reactivity control mechanism of a micro reactor based on the U-Battery. The U-Battery is based on remote deployment and therefore it is favourable to provide a long fuel lifecycle. This is achieved by implementing a high fissile loading content, which proves challenging when considering reactivity control methods. This article follows the design methodology used to overcome these issues, with an emphasis on a new concept of a moveable moderator which utilises the size of the U-Battery as a small reduction in moderation provides a significant reduction in reactivity. The latest work on this project sees the moveable moderator investigated during a depressurised loss of forced coolant accident, where a reduction of moderator volume increases the maximum fuel temperature experienced. The overall conclusion is that the maximum fuel temperature is not significantly increased (4 K) due to the central reflector region relatively lower volumetric heat capacity compared to that of whole core. However, a small temperature increase is observed immediately after the transient due to the central reflector removal because it reaches energy equilibrium with the fuel region faster.

Keywords

Acknowledgement

This work was undertaken during a secondment to JAEA. It is the authors wishes to thank JAEA for their kind hospitality and contribution towards this work. A part of this work was undertaken under the Nuclear FiRST Centre of Doctoral Training, which was funded by the EPSRC - EP/G037140/1. Further funding to present this work at the ICAPP conference has been provided by NNL's Early Careers team via the postdoctoral development scheme.

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