II — 1. Introduction

The APWR+ is a four loop type PWR with 1750 MW(e) output, which is being developed as the successor of APWR and conventional PWRs, aiming at more enhancements in economy, safety, reliability, reduction of the operators’ workload, and harmony with the environment. The development is being carried out by Japanese PWR utilities (Kansai Electric Power, Hokkaido Electric Power, Shikoku Electric Power, Kyushu Electric Power, and The Japan Atomic Power Co.) and Mitsubishi Heavy Industries.

APWR+ employs the following concepts for its safety system including passive features:

a) Passive safety equipment and system

• Core cooling using steam generator and natural circulation of the primary system during

accident

• ‘Advanced Accumulators’ and ‘Advanced Boric Acid Injection Tank’.

b) Four train configuration

c) Confinement of energy release to the containment

• The core and the loop piping are submerged in case of a LOCA

d) Enhancement of the design diversity

• Emergency power supply by Diesel and gas turbine

• Heat removal paths from the containment

Figure VI-1 shows the features of APWR+ safety related systems.