Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 1 Rev.: Beneficiary:Rosenergoatom Contractor:Empresarios Agrupados Local Subcontractor:Mocht Otjig Budget: € Duration:27 months Contract expired:February 1996

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 2 Rev.: Objective of the project Develop a methodology of work for life-time evaluation of Systems Structures and Components (SSC) Review input information submitted by Russian experts, especially from Novovoronesh (NV) Units 3 and 4 Identify weak points and major problems with impact on safety Transfer Western experience in life-time evaluation methods to Russian experts Review results from Kozloduy 6-Months program and adopt them to NV Define the focus of the project based on Kozloduy review Recommend refurbishment and improvement to ensure safe and reliable operation at NV

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 3 Rev.: Project implementation Task 1; Development of a methodology to perform evaluations as follows: –Review of previous work carried out in Novovoronesh NPP –Pre-classification of NV NPP equipment –Determination of factors affecting the life-time of the equipment in each group of the classification –Establishment of methods for evaluation of residual life-time for equipment in each group –Methods of inspection at site and identify needs for additional inspections –Identification of Normative Documents

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 4 Rev.: Project implementation (cont.) Task 2; Identification of weak points in the selected SCC –Review of results from Kozloduy 6 months program –Identification of weak points –Walk-down in Novovoronesh –Analysing loading histories –Final report

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 5 Rev.: Steam generators Main valves Electrical equipment Instrumentation and control components Heat exchangers and condenser Main turbine and main generator Emergency diesel generators Reactor Pressure Vessel Reactor internals Primary coolant pumps Pressurizer Piping Piping support Spent fuel pool Main pumps Cranes The following SCC were defined and selected in the ToR for evaluation of degradation and life-time assessment: Project implementation (cont.)

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 6 Rev.: Project implementation (cont.) Principal flow diagram for life management of SCC

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 7 Rev.: Project implementation (cont.) Development of methodology

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 8 Rev.: Project implementation (cont.) main turbine Example of an evaluation matrix for degradation modes; main turbine

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 9 Rev.: Overview of project results For each of the above selected SCC the degradation mechanisms were evaluated and documented in a evaluation matrix As an example the evaluation results of the RPV is shown in the following:

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 10 Rev.: Degradation mechanisms: High level of importance –Irradiation embrittlement of core region welds and shells –Influence of annealing –Re-embrittlement after annealing Medium level of importance: –Fatigue (bolts and threads) –Mechanical wear (bolts and threads) –Boric acid corrosion –Fatigue crack growth (main nozzles, upper head penetrations, bolts and threads) Overview of project results

Tacis 1.14/91 on life-time evaluation TACIS Project: R8.01/98 – TRANSLATION, EDITING AND DIFFUSION OF DOCUMENTS (Result Dissemination) Tacis R1.14/91, “Residual Life-time evaluation” Slide 11 Rev.: Recommendations for managing RPV degradation Validation of annealing; –Test results from Tacis 1.1/91 “irradiation embrittlement” are important –Further testing on samples from NV 3 and 4 considered necessary –Influence of irradiation embrittlement, annealing and re-irradiation of core weld HAZ needs clarification –Determination of the original toughness properties (T ko ) of the sampled welds (NV 3 and 4, Kozloduy 1 and 2, Kola 1 and 2) is important –Validation of correlation between Charpy V and fracture toughness –Validation of the shift in fracture toughness due to irradiation by means of Charpy shift –Validation of correlation between sub-size and standard Charpy specimens –Upgrading of Pressurized Thermal Shock (PTS) studies nesessary Overview of project results (cont.)