Assessment of Hitachi-GE Allocation of Function for the UK ABWR

1.1 In January 2014 ONR formally started Step 2 of the GDA of Hitachi General Electric’s (Hitachi-GE) UK Advanced Boiling Water Reactor (UK ABWR). Hitachi-GE is the Requesting Party for the UK ABWR GDA (referred to as “the RP” in this specification). 1.2 Step 2 concluded in August 2014 and involved an overview of the acceptability, in accordance with the regulatory regime of Great Britain, of the design fundamentals, including review of key nuclear safety and nuclear security claims with the aim of identifying any fundamental safety or security shortfalls that could prevent the issue of a Design Acceptance Confirmation (DAC) (see http://www.onr.org.uk/new-reactors/ngn03.pdf). 1.3 During Step 2, ONR reviewed the key claims (assertions) put forward by the RP in the area of Human Factors (HF).

Some of these claims relate to the adequacy of Allocation of Function (AoF) for the UK ABWR. ONR’s technical assessment reports covering the assessment work done during Step 2 and key conclusions are published on ONR’s website (http://www.onr.org.uk/new-reactors/uk-abwr/reports.htm). 1.4 During Steps 3 and 4 of GDA ONR will undertake assessments that will increase in detail as GDA progresses, to confirm that the claims are supported by adequate arguments (reasoning) and evidence.

ONR started Step 3 on 1 September 2014 and expects to complete it at the end of August 2015. 1.5 During Step 4, ONR will assess the evidence by conducting in-depth reviews, on a sampling basis, of the HF aspects of the UK ABWR safety case and supporting analyses, to confirm that the claims and arguments are underpinned by robust evidence. ONR expects to start Step 4 of GDA on 1 September 2015 and complete it at the end of 2017. 1.6 In the HF topic area, AoF may be considered one of the most important activities in the design of the new plant.

ONR recognises this significance via the Safety Assessment Principle (SAP) EHF.2 which requires that: “When designing systems, dependence on human action to maintain and recover a stable, safe state should be minimised. The allocation of safety actions between humans and engineered structures, systems or components should be substantiated.” 1.7 Automation will be the general concept of operations for the UK ABWR, which will utilise advanced computerised technology extensively, particularly in the Main Control Room (MCR) and to a much greater extent than for current UK nuclear power plants.