F. M. MITENKOV, V. M. RULEV OKB Mechanical Engineering,

Nizhny Novgorod,

Russian Federation

Abstract

A once-through cassette steam generator for an integral reactor is considered. The steam generator consists of separate cassettes and is arranged in the annulus between the reactor vessel and the core barrel. Specific developments of integral reactor designs show that the technical feasibility of their implementation is determined to a substantial degree by the characteristics of steam generator used. This paper describes a steam generator with improved overall and thermotechnical characteristics compared to existing steam generators. The high specific characteristics of steam generator allow development of an integral reactor for 600 MWe NPP.

1. INTRODUCTION

Integral reactors characteristics depend greatelv on the characteristics and structure of the steam generator.

Power rise of integral reactors is limited due to the low specific power of the existing steam generators, in particular those made of helical tubes.

The necessity to locate steam generator inside the reactor vessel causes some additional requirements on its structure, the most important of which are high compactness of the heat exchange surface and high specific power of the steam generator.

OKBM has developed various types of once-through SGs being operated in marine reactor plants PWRs. These SG types, in particular, include:

1) SG made of helical tubes;

2) Cassette-type SG made of straight tube steam-generating elements.

It has been proven by numerous experiments that the specific design of cassette — type SGs with straight steam-generating elements has better specific characteristics compared to SGs with helical tubes other conditions being equal.

For example in the operated cassette steam generators, developed by OKBM specific power in the effective heat-exchange zone reaches 60 MW/m3.

The design of cassette steam generator for VPBER-600 reactor is considered in this report.