Objectives

This contract covers the On-Site Assistance (OSA) type support to a nuclear plant in Ukraine, in the framework of the TACIS project system. However, this project had a special character due to the fact that the recently completed Unit 2 went critical in July 2004, during the contract implementation. Therefore the project represents the first-of-a-kind OSA project to a VVER plant during commissioning.

The contractor provided assistance to the plant staff organisation assessing the implementation of the safety related measures (modernisation, completion, rehabilitation) at Khmelnitsky Unit N� 2. The following specific objectives were declared:

• To check the actual implementation of the safety improvement measures through relevant technical solutions intended to solve or lower the priority of the issue at least from IAEA ranking level III to level I.
• To verify that the issues related to rehabilitation and completion have been properly addressed.

Background

EDF and Iberdrola/Sogin, the European nuclear operators already providing On-Site Assistance at Rovno and Khmelnitsky NPPs, respectively, were requested by the EC to assist Energoatom in checking the good implementation of safety related measures at Khmelnitsky 2 (and also at Rovno 4). The present contract was placed with Iberdrola/Sogin and a separate contract (see 32255) was placed with EDF for similar activities in relation to Rovno Unit 4. However, both contractors were required to coordinate their activities as well as the results of their assessments.

Based on on-site assistance principles, experts assisted Energoatom to organize and perform the assessment of the good implementation of measures at Khmelnitsky 2 in the three following fields:

• Modernization (safety measures).
• Completion, in compliance with the original design (for equipment and components important for safety).
• Rehabilitation of equipment already installed.

Project results– achievements

A methodology was developed for the assessment of the safety related measures. The review was carried out and the results agreed with Energoatom. The safety modernisation measures, as categorised by Riskaudit (report 593/637), were assessed by the contractor on the basis of the methodology developed at the beginning of the project. The measures were grouped into packages. For each package the relevant design documentation was gathered and translated into English. The analysis of the implementation of the safety measures was carried out through a safety review mission. Energoatom was deeply involved in the safety review and approved the conclusions. The good implementation of the completion and rehabilitation measures was assessed in relation to their effect on the safety related equipment. The measures addressed by the Task 1A (Assessment of the most urgent measures identified) covered the following areas:

• Embrittlement surveillance program
• High energy pipe breaks
• Fire safety analysis (including cable compartments)
• Cable coating
• Fire detection system
• Fire doors
• Fire damping valves
• Fire resistance of the turbine hall structure
• Smoke prevention system
• Fire suppression in the I&C rooms with automatic gas fire fighting systems
• Insulation materials
• Analysis of the welds on the main steam and feedwater lines
• ECCS passive accumulator – preheating issues
• Replacement of the inverter for the emergency supply
• Capacity of the batteries.

The measures addressed by Task 1B (Assessment of the remaining modernisation measures) were in the following fields:

• Studies
• I&C
• Plant balance
• Operational safety
• Equipment testing and qualification
• Commissioning tests
• Electrical equipment
• Building stability
• Core neutronics
• Radiation embrittlement
• Mechanical systems.

The results obtained during the assessment of the implementation of the measures can be summed up as follows:

• 62 pre-commissioning measures were fully implemented in accordance with the Riskaudit report 593/637.
• 4 measures were implemented partly after commissioning in accordance with the Riskaudit report 593/637.
• 11 measures had some changes in scope or schedule regarding Riskaudit report 593/637. These changes were assessed to be acceptable by the Consultant.
• 3 measures could not be fully assessed because further information was required from Energoatom. The measures had been declared as completed by Energoatom, and the Consultant expected that when the required information would be received, the measures would be assessed as having been satisfactorily implemented.

Regarding the rehabilitation and completion programmes, the selection of the representative equipment was made according to their safety importance. The assessment results revealed that both programmes were implemented effectively.