Beneficiary Organisation: Energoatom
1) Background
The Ukrainian utility Energoatom is one of the beneficiaries of the Tacis nuclear safety program launched by EC for improving safety of NPPs in the countries of the former Soviet Union. In the year 2000 the EC-Utility RWE Power Biblis took over the OSA responsibility in the ZNPP. This support project was dedicated to the ZNPP, which is situated at the Dniepr river in Atomgorod. The ZNPP consists of 6 electricity generating NPP units of type VVER 1000-V320. This NPP has the largest nuclear electricity generating capacity worldwide. During the erection of ZNPP in the early eighties, the pressurizers in units 1-4 were equipped with pilot operated safety valves (POSV) of the western supplier Sempell AG. The Pressurizer in units 5 and 6, however were fitted with Russian made safety valves. Later this valves were replaced by safety valves of the new design by Sempell AG. Thus all safety valves in ZNPP are currently of the same type and provider.
2) Objectives
In terms of safety and reliability of operation of an NPP, the safety valves of the pressurizer belong to the most important protective safety devices and they must accordingly be thoroughly tested and re-adjusted during each refuelling outage of the unit. Therefore, a device enabling to perform reliable functional testing and accurate adjustments of the safety valve is a most essential device for the ZNPP. EC and the beneficiary decided to launch this specific Tacis support project U1.03/96D2, with the objective to purchase a modern computer aided system for testing and adjusting of the safety valves and thus contribute to improvement of safety of the ZNPP. The selected test bench supplier was Sempel AG.
3) Project results–achievements
The computer aided testing device purchased under this specific project consisted of a pneumatic lifting device, a control unit for providing compressed air, a measurement unit with pressure and stroke sensors, a notebook for handling of data, printer and software. The project sequences were:
• Manufacturing process
• Factory acceptance tests
• Delivery of equipment
• Training of personnel
• Provisional acceptance
• Warranty/after sales
• Final acceptance

The project was completed satisfactorily and the final acceptance certificate was signed on the 3rd of February 2004.

The main contribution of the computer aided testing device purchased under this contract was to:
• Visualize the functional tests in order to improve the assessment of the valve operability and functional test;
• Carry out testing of valves by remote control, thus reducing radiation exposure on personnel;
• Increase the accuracy of valve settings;
• Collect comprehensive data related to the condition of the safety valves enabling to assess the quality of maintenance work etc.
4) Comments
The lack of some essential parts required for connecting the test device with the safety valves was noticed only late in the course of factory acceptance testing. Thes important parts were omitted in the Technical Specification (TS). This omission caused a delay of the delivery by 9 months.
Further Information
Further information on the project results could be sought from the beneficiary organizations.
The final report is available at the DG JRC-ie archive
Further reference may be found under a project with title: Computer Aided testing Device for the Pressurizer Safety Valve - part I (U1.03/96D).