R2.04/94 - R2.05/94

R2.04/94 - Water level instrumentation

The present water level measurement system used in VVER reactors was not reliable and had to be modernized in order to avoid uncertainties of the actual water level, especially under accident conditions. The Russian Beneficiary asked for the modernization of the water level measurement system in operating NPP.

With the present project, the following tasks were expected to be performed:

• analysis of the system for water level control (sensors and associated auxiliary equipment) developed and used in RF and EU;
• experimental confirmation on Russian test facilities of the operational capability of four sensors (2 for VVER 440 and 2 for VVER 1000) based on thermal effect and presently developed in RF.

Four (4) sensors to be included in one (1) system had to be tested. Sensors and cables limited to the boundary of the containment only had to be tested.

R2.05/94 - Modernization neutron flux and temperature measurement.

In the present VVER NPP, the in-reactor control system (VRK) consists of neutron flux detectors and temperature detectors. Seven neutron flux detectors are located along the core axis within the neutron measuring channels.

This project aimed at the improvements of temperature/flux sensors part of the in-reactor control system, and the methodology to evaluate the status of the equipment of in reactor control system within the containment.
The characteristic of the equipment of in-reactor control system of Kola Units 3 and 4 and Kalinin Units 1 and 2 had to be evaluated.

R2.04/94 - Water level instrumentation

As the project was contracted to the same Contractor and the same Local Subcontractor as R2.05/94 the project implementation took place in parallel. This was necessary as both projects had much in common and therefore a parallel work was essential for the project’s success.
Similar were the gained results. On the basis of the obtained results, the Russian water level sensors can be considered in principle qualified and suitable for future utilization in VVER reactor pressure vessels. The implementation of the tested equipment is recommended and would impact on a safety increase. However, a full length/full scale prototype assembly in-reactor testing, including relevant electronics, should be considered.

As a result of the investigations and evaluations performed, the VVER in-core reactor control systems can be improved by using the new developed Russian neutron flux/temperature measuring assemblies, without and with integrated water level sensor (KNIT and KNITU assemblies, respectively). The integration of the water level sensors in other in-core monitoring assemblies is beyond the expected results and may be seen as a positive synergy. In addition to the validation of the in-core equipment, sensors and assemblies, additional areas of improvements have been identified for their effective and safe exploitation, in particular the system approach for the qualification of the overall in-core monitoring system in post-accident conditions. Moreover, proposals for the modernization of the in-core instrumentation have been done for Kalinin and Kola NPP.

Achievement of specific project objectives
At the start the project faced some problems. Afterwards, however, the performance of the project activities has constantly improved, which has allowed the parties to overcome successfully the difficulties of the project implementation.

The joint team of involved experts has shown ability and effectiveness to achieve the planned objectives. The establishment of a good joint expert team during the implementation of the activities, able to solve complex and difficult problems, is considered by the Local Subcontractor one of the most significant achievements to assure the project’s success.

R2.05/94 - Modernization neutron flux and temperature measurement.

As the project was contracted to the same Contractor and the same Local Subcontractor as R2.04/94 the project implementation took place in parallel. This was necessary as both projects had much in common and therefore a parallel work was essential for the project’s success. Similar were the gained results. As a result of the investigations and evaluations performed in this project, the VVER in-core reactor control systems can be improved by using the new developed Russian neutron flux/temperature measuring assemblies, without and with integrated water level sensor (KNIT and KNITU assemblies, respectively).

The integration of the water level sensors in other in-core monitoring assemblies is beyond the expected results and may be seen as a positive synergy. In addition to the validation of the in-core equipment, sensors and assemblies, additional areas of improvements have been identified for their effective and safe exploitation, in particular the system approach for the qualification of the overall in-core monitoring system in post-accident conditions. Moreover, proposals for the modernization of the in-core instrumentation have been done for Kalinin and Kola NPP.

Achievement of specific project objectives
At the start the project faced some problems. Afterwards, however, the performance of the project activities has constantly improved, which has allowed the parties to overcome successfully the difficulties of the project implementation.

The joint team of involved experts has shown ability and effectiveness to achieve the planned objectives. The establishment of a good joint expert team during the implementation of the activities, able to solve complex and difficult problems, is considered by the Local Subcontractor one of the most significant achievements to assure the project’s success.