Establishment of a system for monitoring technical conditions of NPP buildings and structures based on advanced methods and techniques (U1.05/12)

The overall objective of the project was to establish an improved system for continuous monitoring, evaluating and maintaining structural integrity of safety-related buildings and structures of a nuclear power plant (NPP).

The structural integrity assessment uses monitoring characteristics of most critical components of NPP buildings and structures. The data are then analysed to determine that the buildings and structures are sufficiently robust to withstand both design-based and beyond-design extreme conditions.

The Beneficiary of the project was NNEGC Energoatom (EA), the Ukrainian nuclear power plant operator.

The specific objectives of the project were to:

• Develop a programme of Buildings and Structures (B&S) condition monitoring and integrity management; the programme should include monitoring processes, integrity management principles and personnel qualification requirements
• Develop a B&S monitoring software based on the principles and methodologies of the B&S monitoring programme
• Prepare technical specifications of a B&S integrity monitoring equipment according to the B&S monitoring programme
• Develop training programmes and materials; train personnel of the relevant directorates of the EA Headquarters and NPPs in the methodologies and practice of the B&S monitoring
• Demonstrate the operability of the monitoring system in order to verify the methodologies and software models
• Disseminate project outcomes to all Ukrainian NPPs

The project was implemented in seven tasks. The Khmelnitsky NPP Unit 1 was the Pilot Plant (End User). Representatives from non-pilot NPPs were also involved in the project implementation.

Within the specific project tasks, the contractor achieved the following results:

Task 2: Review of international and Ukrainian practice in integrity management of safety related NPP structures and buildings to identify gaps

The contractor compared the Ukrainian practices in structural integrity management with the international rules and standards, IAEA guidelines and practices going beyond the standard requirements. The gap analysis concluded that the Ukrainian practices met IAEA requirements and rules and in some cases met the best international practices. The contractor provided a set of recommendations for improvement.

Task 3: Development of a comprehensive Programme, Methodology and Procedural Guidelines for B&S Integrity management

The contactor prepared an Integrity Management Programme Methodology. Using building design information, it proposed three types of survey: visual inspection, regular measurements and continuous monitoring. For each type of survey, a procedural guideline was prepared including:

• Procedure for assessment of technical condition of the building
• Acceptance criteria for B&S component integrity
• Working procedures and flowchart of integrity management activities
• Routine schedules for integrity inspections, data evaluation and reporting
• Organizational structure and personnel responsibilities and qualifications

Two demonstrations of a sample Automated Monitoring System were performed.

Task 4: Development of a B&S Integrity Monitoring System software

The contractor developed a structural model of the pilot NPP reactor building in the ANSYS code. The model was transferred to the Beneficiary/End user along with the necessary documentation.

The contractor also developed a software for structural integrity monitoring and analysis using data from plant field sensors. The software provides for trend evaluations, alarm functions and building condition rating. The contractor delivered the software with a related documentation and installed it on End User’s computers.

Task 5: Development of B&S Integrity monitoring system design

The contractor prepared technical specifications for the B&S Integrity Monitoring System hardware procurement, System installation instructions, System operation instructions and System maintenance procedures.

Using the structural model developed in the Task 4, the contactor performed structural analysis of the reactor building (containment) for normal operation loads, earthquake, tornado and containment leak test. Tendon loads were also calculated. The contractor delivered the ANSYS files with the load database and the analysis results to the Beneficiary/End User.

Based on the structural analysis, the contractor proposed integrity sensor locations. The contractor reviewed locations of the integrity monitoring sensors currently installed at the pilot NPP. Following the Best International Practices and to utilize the monitoring software features, the contractor suggested the End User to install additional sensors.

Task 6: Demonstration of operability of the proposed B&S integrity monitoring system.

The contractor organized the demonstration to show that the monitoring software developed in the Task 4 was able to collect data from the sensors specified in the Task 5. The contractor staff demonstrated how the monitoring software processed and displayed the acquired data in simulated events including earthquake, tornado, tendon lift-off, tendon rupture, containment leak test and sudden increase in containment temperature and pressure.

Task 7: Training and dissemination of the Project results

The contractor organized a technical workshop on each technical task and a final dissemination meeting. Three additional training sessions were delivered on:

• Structural Integrity Monitoring Programme
• Structural Integrity Monitoring System (software and hardware)

Structural integrity modelling and analysis using the ANSYS engineering simulation and 3D design software.

Conclusions and recommendations

The contractor completed all project tasks as required by the project Terms of Reference (ToR).

Due to difficulties in verifying the ANSYS Structural Modelling and the Monitoring System, together with installing the monitoring software, it was necessary to extend the project duration. The contractor also attributed some delays to late response of the Beneficiary/End User to the documents produced.

Upon recommendations made in the project, a central team of Ukrainian Nuclear Experts has been established. The EA will enhance its on-line B&S integrity monitoring system and upgrade some current hardware. The EA will further validate and refine the structural model developed in the project to meet future EA needs in the NPP structural integrity management. The EA will also investigate the need of additional sensors in the Reactor Building and in other safety-related buildings.