Abstract
This paper describes the design, implementation and characterisation of an Autonomous Reactivity Control (ARC) system in a small modular lead-cooled fast reactor. The aim of this work was to demonstrate the applicability of the ARC system and to study its dynamic behaviour during an anticipated transient without scram. A simplified one-dimensional model was developed to calculate the heat transfer within the ARC system, and the reactivity worth as a function of the neutron poison’s insertion into the active core was obtained via static neutronic calculations. By coupling the aforementioned models, the ARC’s time-dependent reactivity was derived as a function of the coolant outlet temperature variation. This model was implemented into the BELLA multi-point dynamics code and transient simulations were run. A control rod ejection accident was studied leading to an unprotected transient overpower scenario, in which 350 pcm reactivity was inserted during one second. It was shown that the ARC system provides a forceful negative reactivity feedback and that steady-state temperatures after the transient were reduced by almost 300 K compared to an identical transient without its action. In this scenario, the ARC system managed to stabilise the coolant outlet temperature at a value 100 K above nominal conditions. The implementation of an ARC system provided the reactor with a passively actuated self-regulating reactivity control system able to insert large amounts of negative reactivity in a short amount of time.
Highlights
In one of the more recent major reports published by the Intergovernmental Panel on Climate Change (IPCC), SPECIAL REPORT: Global Warming of 1.5 ◦C [1], nuclear power is modelled to increase its total capacity with between 98 % up to 501 % in the year 2050, compared to the installed capacity in 2010
In this paper the Autonomous Reactivity Control (ARC) system [2,3,4], developed by Dr Staffan Qvist, is implemented into the small modular lead-cooled fast reactor (LFR) SEALER-UK [5], and its behaviour is assessed during an Anticipated Transient Without SCRAM
In this paper we investigated the impact on core safety, and core temperatures, when implementing the ARC system in a small lead-cooled fast reactor
Summary
In one of the more recent major reports published by the Intergovernmental Panel on Climate Change (IPCC), SPECIAL REPORT: Global Warming of 1.5 ◦C [1], nuclear power is modelled to increase its total capacity with between 98 % up to 501 % in the year 2050, compared to the installed capacity in 2010 To achieve this ambitious target, many of the obstacles currently facing large scale nuclear power construction projects, e.g. cost overruns or increased safety requirements, needs to be overcome. In this paper the Autonomous Reactivity Control (ARC) system [2,3,4], developed by Dr Staffan Qvist, is implemented into the small modular lead-cooled fast reactor (LFR) SEALER-UK [5], and its behaviour is assessed during an Anticipated Transient Without SCRAM. First order solution methods are employed to study the dynamic behaviour of the reactor with and without the passive safety system installed
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