The SG is moved into the RB with the steam dome entering first.

The SG is separated from the remaining RCS by cuts at the primary nozzles.

SG lifting is achieved by a 400 ton wire jack. This wire jack is supported by an axial bearing which allows rotation of the hanging steam generator about its vertical axis.

SG - Steam Generator,

The SG is carried by two supports when set onto the sliding system:

- Dismantling of the existing blowdown (BD) pipes inside the steam generator cubicle,

With these measures the polar-crane bridge is capable of handling the SG load without structural modifications.

where a vertical thrust force is generated.

When the steam generator has reached the upper level, it is shifted towards the sliding system at EL 115 m on which the SG is moved into the RB.

A break that is postulated immediately after the 90-degree elbow above the steam generator would cause a horizontal thrust force.

Blowdown system

The characteristic data of the steam generators are:

An example is a steam-generator tube rupture.

- storage of old steam generators,

1.1 Steam-Generator Rigging and Handling

essentially by including detailed mass characteristics of the piping and equipment (steam generators, reactor-coolant pump, reactor pressure vessel with internals).

- installation of a revised blowdown piping in the steam generator compartment to balance the flow from the two blowdown connections provided on the replacement steam generator and to get a flow equal to 5% of nominal feedwater flow in the new piping at the connection with the existing piping (possible later modifications of BD system for higher flow, without any works in the cubicles),

- dimensional adaptation of SG supports.

The uppermost lumped mass is placed at the top of the steam generator.

4 WELDING OF CIRCUMFERENTIAL WELDS AT THE STEAM-GENERATOR SHELL

The lifting system enables vertical hoisting and horizontal shifting of loads. After take-over of the steam generator from the transport trailer in the horizontal position the SG is lifted by 4 x 200 ton wire jacks.

The SG transport consists of the following main steps (see figure 1):

- OM 3 survey of new SGs after weld-edge preparation,

Design, manufacture and testing of the new steam generators

- OM 2 survey of new SGs prior to weld-edge preparation,

The outer shell of the steam generator does not have the same diameter along the total length.

The new steam generators arrived on site in September 1999.

As a result, it was decided to replace the present steam generators.

The ground transportation is performed by a self-propelled 14 axle heavy-load trailer.

- outside cut without entering the old SG channelhead;

Steam generator replacement and power-uprating safety analyses

The pipe-shaped beams represent the elastic properties of the shell and steam-generator internals.

- Removal, for clearance purposes, of a section of auxiliary feedwater pipe for removal of existing steam generator and reinstallation once the new steam generator is installed,

The polar crane has an original capacity of 320 tons. But the weight of the new Steam Generator is 337 tons.

Removal, for clearance purposes, of a section of main steam pipe for removal of existing steam generator and reinstallation, once new steam generator is installed.

The trailer to be used has already been employed for previous steam-generator replacements (Ringhals 3, Sweden).

During the SGR, a lot of activities are performed on the secondary systems.

The shut down for the steam generator replacement starts on April 15, 2000.

Evaporate to about 4 ml in a rotary evaporator at a temperature not exceeding 35 _C.

Following the above suggestion of the SNSA, the Krsko NPP filed the application for the commencement of the licensing process for the steam generators' design, manufacture and testing on July 31, 1997. This was followed by the application for the commencement of the licensing process for the replacement of both steam generators and power uprating safety analyses on September 8, 1997.

For the SG lifting from ground level EL 100 m to operation floor level EL 115 m an outside lifting gantry is installed.

3 INTEGRATED LICENSING OF THE STEAM GENERATORS' REPLACEMENT AND UPRATING AT THE KRSKO NPP

For SG replacement surveys, normally 1 to 4 theodolites are used together within one survey.

This is sufficient to allow the SG transport into the RB through this opening. The steam generator's horizontal transfer through the equipment hatch is performed by a sliding system resting below the outside lifting system at EL 115 m.

The same equipment will be used to perform the bevel on the new SG nozzles.

The most unfavorable main steam line break location is postulated in the immediate vicinity of the steam-generator steam nozzle,

Rotation of the steam generator around its longitudinal axis was provided by rotating rolls.

- SG lifting from operation floor EL 115 into the SG housings on EL 108 m

This work package deals with the adaptation of the new steam generators to the existing reactor coolant system (RCS).

- accurate dimensional adaptation of the new SG and existing RCS;