The PSB-VVER project is intended to provide the experimental data needed to allow full validation of the computer codes used in the thermal-hydraulic analysis of VVER-1000 reactors. Currently there are 19 VVER-1000 reactors in operation and several more under construction, mostly in central and eastern Europe. These Russian-designed reactors have design characteristics that are similar to western-designed pressurised water reactors (PWRs). There are however important design differences which necessitate specific experimental facilities and data to ensure that the computer codes are validated and that the results of the thermal-hydraulic analyses are of acceptable quality for this type of reactor. To this end, experiments are to be carried out in a large-scale, thermal-hydraulics facility located at the Electrogorsk Research and Engineering Centre in Russia.

Earlier NEA work established a "code validation matrix” for both LWRs and VVERs. This matrix is essentially a set of phenomena and experimental data that is used to validate thermal-hydraulic computer codes. This led to the general conclusion that the VVER-1000 matrix was not complete. Consequently, it was decided to develop an OECD project to obtain the required experimental data not covered by the matrix.

The project's objective is to provide the unique experimental data needed for the validation of thermal-hydraulic codes and to support refinements to the safety assessment tools for VVER-1000 reactors. The intended PSB-VVER experiments will constitute a relevant extension of the existing code validation database. The data will be of primary relevance to the VVER-1000 system, but they are also of interest to other types of pressurised water reactors.

The intended scope of the project work consists of five PSB-VVER experiments in the following areas:

Extensive pre- and post-test analyses are to accompany the experimental programme throughout the entire experimental series. The possibility of setting up one or more standard problems - either limited to project participants or with broader involvment – will be considered. Three project tests have been successfully carried out and reported upon so far. The test matrix for the remaining part of the programme was discussed and revised by members. The fourth test investigated accidental conditions involving a primary to secondary leak (steam generator header rupture) and was carried out in the first half of 2005. A blind test exercise where the fourth test's outcome will be predicted by calculations before its execution was also organised. The final test will simulate thermal-hydraulic conditions arising after a large-break LOCA in a VVER-1000 reactor, and will be the first one run under these very demanding conditions. A preliminary final test (10% power) was run in January 2008; several attempts for running the final test (full power) were unsuccessful and it was decided to close the Project at the end of 2008 with the agreement that the data of this final test would be provided to the project participants when it would be completed.

Project data

The data abstract is public.

Project participants


USD 1.25 million

Project period

February 2003 to December 2008.

Related links

Last updated: 7 July 2014