Objectives:
The development of a sound basis for reliable evaluation and prediction of the embrittlement effects on VVER 1000/320 type reactor pressure vessel materials is of concern. The shortcomings of the surveillance programme (large scatter in dose rate within a set of specimens, questionable irradiation temperature) and the possible detrimental “nickel effect” are the main safety issues to be addressed.
The aim of TACIS SRR2/95 project was to contribute to the resolution of the above-mentioned shortcomings by improving and harmonising the tools and practices. The related objectives were:

• To establish the state-of-the-art upon neutron spectrum, dose rate and doses evaluations and measurements and to provide recommendations for accurate neutron characteristics evaluation in various typical irradiation locations (experimental and/or surveillance);
• To investigate experimentally further the nickel, dose rate and temperature effects;
• To contribute to the development a physically based neutron embrittlement model by sharing the available knowledge between the project partners and implement more specific examination on selected specimens for the above-mentioned experiments.

Project Description:
Implementation of the project
The work was financed by the Directorate General 1A of the Commission of European Communities under two contracts (25289 & 25291) to a consortium of Belgatom SA, Electricite de France (EDF), Forschungszentrum Rossendorf (FZR) and Siemens KWU (nowadays AREVA), acting as the leader. The global budget was 1.076.900 €.
The Beneficiaries were MINATOM (Russia) and GOSKOMATOM (Ukraine). The local Subcontractor was ATOMENERGOEXPORT assisted by RRC Kurchatov Institute (RRC KI) as the technical leader. Leading experts and organisations from Russia, Ukraine, Czech Republic and Bulgaria were also involved under the technical leadership of RRC Kurchatov Institute.
The global implementation duration of the project was about 46 months. Eight months extension was accepted to compensate for delay in delivery of irradiated specimens (incident at Novovoronezh 5 during the irradiation cycle). The date of entry into force of the 2 related contracts was the 2nd of February 1998. The final completion date was the 2nd of October 2001.
The following 14 tasks were performed in order to achieve the 3 specified objectives:
• Task 1: Test plan;
• Task 2: Measurement of neutron fluence in VVER-1000 reactor vessels (Balakovo-3 and Rovno-3);
• Task 3: Measurement of neutron fluence in test-bench “Korpus”;
• Task 4: Measurement of fluence inside LR-0;
• Task 5: Actual measurement and evaluation of neutron detectors;
• Task 6: Materials for irradiation;
• Task 7: Mechanical test;
• Task 8: Fine-structural investigation;
• Task 9: Precise fluence calculation for VVER-1000 of the test-bench “Korpus” and “LR-0”;
• Task 10: Comparison of calculations and experiments;
• Task 11: Improvement of neutron data: methods and codes;
• Task 12: Calculation of fluences for witness specimens of VVER-1000;
• Task 13 and 14: Correlation and simulation.
Tasks 0 (partly), 1, 2, 3, 4, 5, 6, 7, 9, 10 and 12 were performed under contract 97-0804 and Tasks 0 (partly), 8, 11, 13 and 14 were performed under contract 97-0806.
33 documents were delivered (all in English and some of them in Russian), covering the complete scope of the tasks. The quality of the reports is quite scattered. A considerable amount of information has been summarised and reported, but the process of building-up some of the conclusions and the extent of experts’ recognition of the conclusions is not always visible, despite an important effort in the final report. An additional extension of the 2nd contract was not allowed and, therefore, part of the originally planned tasks could not be fulfilled (e.g. tasks 13 & 14), which restricted the possible conclusions on the most attractive and innovative objective (neutron embrittlement modelling).
See the attached document for more details on the project objectives and results.