Objective
Unit 5 is equipped with four SGs. To protect the SGs and corresponding system of live steam piping from pressure excess (for example at abnormal operation or in case of the accident) the following systems are to be replaced:

• Condenser Steam Dump System Valves;
• Atmospheric Steam Dump Valves;
• Second circuit protection system from pressure excess of SG Safety Relief Valve.

Two safety relief valves (control and working valves) with different action pressure adjustment are installed in each live steam line at the outlet of each steam generator. The SG valves presently under operation on Unit 5 do not meet the present Russian Safety Standards and have to be replaced, which is the subject of this project.
Eight Safety Relief Valves of the Unit 5, comprising the main and pilot valves shall be replaced under this project. Further, a range of spare parts had to be included.
Result
The project has been completed with the supply and installation of the SG-Valves in the following scope and quality:
• Eight main valves and pilot valves including all necessary equipment for I&C and for remote control from the main control room and emergency control room;
• Blocking devices for both each pilot valve and main valve as far as necessary;
• Limit position breaker sets ("open" and "close") for all main valves, pilot valves (with three sets per each main valve and per each pilot valve) and blocking devices (for indication of the state in Main Control Room (MCR), Emergency Control Room (ECR) and registration in the information computer of the unit);
• Testing device for the adjustment of the pilot valves, without dismantling;
• Pressure sensors (three per each pilot valve of each main valve);
• One logic scheme for each main valve (three per each pilot valve of each main valve);
• Components as connecting pipelines of pilot valve with the main valve and live steam pipes;
• Mechanical and electrical control circuits, necessary for the function of the complete safety valve, including:

• Equipment / components to install the pressure sensors;
• Cables to connect control cabinets and pressure sensors;
• Connecting elements, impulse lines;
• Device for leakage indication of each main valve to present the information to the main control room.