Background
In the framework of the TACIS 1992 Nuclear Safety programme, the Commission agreed with the Ukrainian authorities on technical assistance projects to be financed by the European Community in the field of nuclear safety. One such project was the delivery and installation of a vibration monitoring system for the main primary coolant water pumps of Unit 3 of the Rovno Nuclear Power Plant.
One of the most important criteria of reliability and safety of rotating equipment is the level of vibration. Failures related to high vibration may lead to serious consequences such as failures of separate components of rotating equipment and in some cases to service accidents. Most of these failures can be anticipated and prevented by an adequate vibration monitoring system. The installation of such a system on large rotating equipment will increase the protection level of the individual equipment and consequently of the plant as indications, alarms and automatic actions if deemed necessary, are provided to prevent equipment failures. The recording and analysis of all data and information obtained from those automatic and permanent systems and also from portable instrumentation, will provide valuable data and information for predictive and corrective maintenance and for plant operation which contribute to plant safety.
The thermohydraulic parameters (temperature, pressure, flow, etc) of the main cooling water pumps of Unit 3 of the Rovno NPP were permanently monitored during normal operation by a Unit computer. In addition, monitoring of vibration was obtained by manual measurement of vibrations made every month by plant personnel.
These two approaches did not give satisfactory protection for the main cooling water pumps. For this reason, it was decided to develop a modern continuous monitoring system to be combined with the existing monitoring methods.
Objective
The project concerned the supply and installation of a continuous monitoring system for the main cooling water pumps of Unit 3 which was able to provide:

• Warning of major risks in the interests of security and safety;
• Detection as early as possible of malfunctions to avoid damage and loss of production;
• Analysis of malfunctions and incidents to assess the gravity and to define appropriate remedial or preventive actions.

Use of the system would contribute to the accumulation of knowledge of behaviour of the main cooling water pumps and of the characteristic signals corresponding to faults, to increase the capacity for diagnosis during operation.
The supply comprised:

• The vibration / dynamic measurement sensors (piezo-electric accelerometers, eddy current sensors, rev pulse device);
• The signal converters;
• The data acquisition system for both vibration and thermohydraulic signals (the thermohydraulic signals are provided by the existing sensors);
• The signal processing computer with monitor, keyboard, printer and hard disk storage;
• An auxiliary workstation;
• Terminal blocks and cables;
• Links between the data acquisition system, signal processing computer and auxiliary workstation;
• Required software;
• LAN links;
• Power supply system;
• Server;
• Spare parts;
• Accessories and consumables required for 2 years of operation;
• Documentation;
• Supervision of installation, commissioning, testing;
• Training of End User personnel for the installation, operation and maintenance of the system;
• After sales service – 6 visits to the NPP by the supplier during the 2 year warranty period.

Results
The contract was signed in August 1994. Equipment manufacturing was undertaken from July to December 1994. During the plant outage of September 1994 a first batch of sensors was installed. The remainder of the equipment was delivered in February 1995 and was installed from May to July. From November 1995 to January 1996 the on-site acceptance testing was performed along with personnel training. The Provisional Acceptance Certificate following successful installation, testing and commissioning was signed in February 1996. Final Acceptance was pronounced in May 1999.