J. P. ORDONEZ,

INVAP S. E.,

San Carlos de Bariloche,

Argentina

Abstract

The paper presents the design related aspects of operation and maintenance of the CAREM reactor and the principal features of its main components.

The paper covers three main topics: operational aspects, major components and

maintainability

Operational aspects

A strong negative thermal coefficient, the use of burnable poisons to compensate burnup and no use of soluble boron for reactivity control characterized reactor control.

Hydraulically driven control rod drives are fully contained in the pressure vessel.

The following research and development activities are being carried on:

A critical facility for testing main core characteristics is in final construction stage.

A full scale model of control rod drives is currently under test.

A full scale model of one steam generator will be constructed and tested.

Major components

Pressure vessel: The empty pressure vessel weights 100 tons. This fact facilitates both its manufacturing and transport. Internals and steam generators will be mounted on site. Being the reactor self-pressurized, no pressurizer is included.

Steam Generators: Twelve once-through steam generators are symmetrically placed inside the pressure vessel. Specific design aspects are discussed in the paper.

Containment: The containment is of pressure suppression type. Second shutdown system, pressure relief tank, and equipment and installation for manual reactor refueling and for handling of RPV internals, are all placed inside the containment. Provisions are also made for accommodating RPV internals during refueling and maintenance operations.

Maintainability

Lay-out: The balance of plant lay-out is conventional. For nuclear island layout, attention has been paid to the fact that the containment will not be accessible during reactor operation. This fact imposes special demands on equipment reliability, that will assure high plant availability.

In service inspection: it is currently under study. Inspection of pressure vessel welds will follow standard practices. Inspection of steam generators will be performed by conventional eddy-current techniques adapted to tube geometry. Other in-service inspections required by ASME XI, SS-50-SG-O2, and local regulatory authorities, are being evaluated, most of them being similar to the standard for non-integrated reactors.

Fuel and waste handling: manual refueling of the reactor implies changing 31 fuel elements (approx. 70 kg each) per year. Spent-fuel-pool capacity covers seven years of operation; afterwards, dry spent fuel element storage is considered.

Decommissioning: The CAREM concept does not impose specific conditions on plant decommissioning.

1. INTRODUCTION

CAREM reactor features have been described elsewhere /1/. This paper deals with detailed engineering aspects of its design, that point to important differences between the CAREM, and conventional non-integrated PWRs.

The main aspects to be discussed are:

— Operational aspects, including reactor control and control devices.

— Major components engineering: reactor vessel, steam generators and containment

vessel

— Maintainability, as related to lay-out, in-service inspection, fuel and waste handling,

and decommissioning.

The R&D status corresponding to each item is mentioned when convenient.