R2.03/94 : STUDY TENSIONING MACHINES

The existing stud tensioning machines (Reactor Pressure Vessel - RPV, Main Cooling Water Pump - MWCP) which are used in the different NPP and Rosenergoatom facilities shall be investigated in order to upgrade or back fit them as appropriate.

The main objectives of the project were to propose an upgrade of the RPV Stud Tensioning Machine (STM) presently in use at different VVER 440 and 1000 NPPs. The task included first to assess whether the upgrading is possible overall and in the case of a negative result to justify that the desired upgrading cannot be accomplished. In this case a cost estimation of a new stud tensioning machine for VVER 440 and VVER 1000 were to be provided.

The deliverable of this project shall be a report on the existing equipment, the quality status, the necessary technical improvement and budget figures for improvement and back fitting with components from CIS or abroad.

A prototype improvement of existing CIS equipment for the MCWP will be performed under this project.

The following outputs have been produced:

• Quality assurance plan in August 1996;
• Assessment report of present Stud tensioning machine (STM);
• Quality status report of equipment;
• Calculation report for existing STM and Interim statement;
• Design documents for the proposed improvement have been replaced by design documents for the new equipment as a result of the declared non-adequacy of the present STM for improvement;
• Test program and methods;
• Manufacturing of one tightening unit;
• Test results, proposals, conclusion reports and cost estimation.

The final conclusion was that considering all technical and financial efforts, upgrading is not feasible.

The specific objectives of the project as per TOR have been met.