Development of Instrumentation and Control Systems for UK ABWR

Abstract

This paper introduces the Instrumentation and Control (I&C) system for the proposed UK Advanced Boiling Water Reactor (UK ABWR) offered by Hitachi-GE Nuclear Energy, Ltd (Hitachi-GE). Hitachi-GE has been progressing the UK Generic Design Assessment (GDA) licensing process over the last 3 years. This is the process through which the Office for Nuclear Regulations (ONR) assesses the UK ABWR for suitability from a nuclear safety, security, environmental protection and waste management perspective and it is the first step towards proceeding with the construction phase in the UK. ONR’s regulatory expectations setting out relevant good practice are described in the Safety Assessment principles (SAPs), which are considered into the I&C design for UK ABWR. In addition, it has also been designed to take into account relevant good practices and regulations. In accordance with expectations derived from SAPs, the UK ABWR I&C systems are categorized and classified as required by IEC 61513 and IEC 61226. In addition, the overall I&C architecture, including all associated Human-Machine Interfaces (HMIs), abides by the principles independence and diversity of safety measures, segregation and separation of the protection and control systems. As a result, the UK ABWR I&C architecture is composed of major eight sub-systems. The eight sub-systems are: -Safety System Logic and Control system (SSLC) -Hardwired Backup System (HWBS) -Safety Auxiliary Control System (SACS) -Plant Control System (PCntlS) -Reactor/Turbine Auxiliary Control System (RTACS) -Plant Computer System (PCS) -Severe Accident Control and Instrumentation system (SA C&I) -Other dedicated C&I systems. The features for each sub-system such as redundancy of safety train or segregation among divisions are specified so that each sub-system will achieve its reliability as well as increase availability. While in the Japanese ABWR safety I&C system, the main protection system (SSLC), is microprocessor-based from the decades of successful operating experience in the past BWR, to meet the UK regulatory regime expectation on diversity between Class 1 platform and non-Class 1 platform, the SSLC (Class 1) for the UK ABWR is by Field Programmable Gate Array (FPGA). This system is currently under development and complies with IEC 62556. Its safety integrity level is planned to be SIL 3 (as a single division) and SIL 4 (as a four division system) as defined in IEC 61508. The HMIs which constitute an integral part of the I&C systems are also designed to comply with the I&C architecture regarding their categorization and classification with consideration of Human Factors (HF) modern methods taken into accounts.