Fixed and portable (mobile) equipment for severe accident prevention and management at UK ABWR

It is planned to build Advanced Boiling Water Reactors in the UK, adapting the pre-Fukushima reference design to satisfy UK regulatory expectations. The paper will describe the features of the UK ABWR to respond to events which lead to or involve a loss of first-line protective systems and the timing of their deployment. Some provisions are required to operate in relatively short time (up to a few hours after loss of the principal safety system) and are integrated within the plant design; for example, Remote Shutdown System panel, and Back-up Building control panel. Other defence-in-depth features (e.g. mobile equipment) have a longer allowable deployment time and hence can be mobile and require significant operator actions to initiate. The UK ABWR accident management strategy is for the site to be self-supporting for 7-days, necessitating access to secure supplies of fuel and water stocks. The paper will discuss the continuity of electrical and water supplies supporting delivery of cooling water to the reactor fuel to prevent core damage, plus features in the design to prevent failure of the containment boundary. The development of SAM guidelines for operation of such equipment will be described, and the approach planned to be taken to provide confidence in operability in extreme external events and/ or severe accident conditions. (author)