SEVERE ACCIDENT MANAGEMENT

The primary objectives of the project were:
a) Severe accident codes and phenomenologies
To transfer the Western technology and experience on Severe Accident analysis, including off-site consequence analysis, to the Russian counterpart. It consists of a review and comparison of Severe Accident codes to select the most suitable for use in VVER plant analysis, in providing the selected codes and training the Russian experts on their use. A severe accident analysis will then be made for a reference plant;
To assist and collaborate with the Russian experts in the review of SA tests performed in the world and of the modeling in physical phenomena used by the selected codes for their application to VVER plants, to identify phenomena that need additional tests and to make a proposal of the tests to be made;
To assist Russian counterpart in the experimental investigation of selected SA physical phenomena, typical of VVER plants, on the RRC KI facilities, to analyze the results, define new code models, where necessary, and validate those models with the test results.
b) Accident management
To transfer the Western technology and experience on accident management to the Russian counterpart. It consists of a review of the Western AM methodologies and in the analysis of their applicability to the current VVER plants to select the more appropriate approach to adopt;
To assist and collaborate with the Russian experts in the analysis of VVER plants to develop AM measures for prevention of core damage and mitigation of accident consequences, to identify weak areas where improvements are needed and to propose modifications (for example: depressurization of SG secondary side, water supply from external sources, change of accumulator flow rate etc). The validity of the proposed modifications will then be verified by analysis;
To assist and collaborate in the preparation of AM procedures for the reference VVER plant.

Phase 1
The Western approach for severe accident management has been reviewed with regard to VVER 1000 specifities:
Important phenomena for VVER and differences to western PWR behaviour have been identified;
Western tools for severe accident analysis have been reviewed and selected appropriate codes have been transferred to the Russian project partners, together with associated hardware and engineers training;
A detailed model of the reference plant has been established, documented and tested on the most important transients;
Technical difficulties raised by the application of western software to VVER have been investigated and precisely identified. Adequate remediation has been made;
The various western approaches for severe accident management have been described and discussed, leading to the proposal of the bases for the elaboration of a VVER specific approach.
The work performed in Phase 1 was the basis for the continuation consisting of Phase 2 of this project.
Phase 2
The continuation work was intended to elaborate in addition the following:
Achieve realistic methodology developments according to the findings of phase 1;
Produce confirmed results as an input to probabilistic safety analyses;
Investigate the Severe Accident management approach outlined in this phase, based on detailed analysis of accident sequences in VVERs.
However this Phase 2 was not carried out during the project implementation.
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REPORTS
1Progress Report 1st Progress Report31/01/1994
2 Progress Report 2nd Progress Report 31/03/1994
3 Others Project Review Meeting 20/04/1994
4 Progress Report 3th Progress Report 30/06/1994
5 Progress Report 5th Progress Report 31/12/1994
6 Progress Report 6th Progress Report 31/05/1995
7 Task Final Report Phase 1 Final Report (Part 2) 25/10/1995
8 Task Final Report Phase 1 Final Report (Part 3) 25/10/1995
9 Task Final Report Phase 1 Documentation File collection No 18