Mitsubishi's computerized HSI and digital I&C system for PWR plants

ITO Koji¹, HANADA Satoshi², and MASHIO Kenji³

1. Mitsubishi Heavy Industries, Ltd., Kobe 655-8585, Japan (koji_ito@mhi.co.jp)

2. Mitsubishi Heavy Industries, Ltd., Kobe 655-8585, Japan (Satoshi_Hanada@mhi.co.jp)

3. Mitsubishi Nuclear Energy Systems, Inc. Arlington, VA 22209, USA (kenji_mashio@mnes-us.com)

Abstract: The fully computerized Human-System Interface (HSI) system and digitalized Instrumentation and Control (I&C) system of Mitsubishi Heavy Industries, Ltd. (MHI) has been developed and approved in Japan. This design is currently being used in the latest Japanese Pressurized Water Reactor (PWR) plant and in Japan’s Modernization Plan of I&C Systems for Operating PWR Plants. Conventional hard controls are limited to system level manual actions and a Diverse Actuation System. The digital I&C system can ensure defense-in-depth and diversity for plant safety and control, with consequent countermeasures against software common-cause failures. The design includes computer-based procedures and alarm prioritization, relying principally on a HSI system with soft controls, console based video display units and a large, heads up, overview display panel. This design is set to be applied to the US-APWR, a four loop evolutionary pressurized water reactor with a four train active safety system, which is currently under Design Certification Review by the U.S. Nuclear Regulatory Commission.

Keywords: computerized HSI; digitalized I&C; US-APWR; V&V