AER working group D on VVER safety analysis – report of the 2007 meeting

The AER working group D on VVER reactor safety analysis held its 16th meeting in Paris, France during the period 08-09 May 2007. The meeting was hosted by the CEA France. It followed the final workshop on the OECD/DOE/CEA VVER-1000 Coolant Transient Benchmark held at 07 May. Altogether 11 participants attend the meeting of the working group D, 7 from AER member organizations and 4 guests from non-member organizations. The co-ordinator of the working group, Mr. S. Kliem, served as chairman of the meeting.
The meeting started with a general information exchange about the recent activities in the participating organizations. The given presentations and the discussions can be attributed to the following topics:
• Code development and benchmarking for reactor dynamics applications
• Safety analysis methodology and results
• Future activities
New solutions for three different benchmarks were presented and discussed. These are the Second AER Dynamic Benchmark on control rod ejection at hot zero power (S. Kliem, FZD), the VVER-1000 Coolant Transient Benchmark (E. Syrjälahti, VTT) and the stationary AER-FCM101 Benchmark considering a VVER-1000 reactor (C. Parisi, UniPisa).
A. Kereszturi (AEKI) presented a statistical evaluation of the possibility to observe a fuel assembly misloading event. The second presentation of E. Syrjälahti was dedicated to the description how best-estimate coupled code calculations at VTT are supported by uncertainty and sensitivity analyses. K. Velkov (GRS) presented preliminary results of BIPR8KN/ATHLET calculations with a very detailed resolution of the calculation grid on the assessment of coolant mixing inside VVER-1000 assembly heads. Coolant mixing experiments at three different mixing test facilities, modeling different reactor types, were presented and compared by S. Kliem. A calculation study using the coupled code system KORSAR/GP on the consequences of the injection of a slug of unborated water into the reactor core was described by G. Ponomarenko (Gidropress).
A list of the participants and a list of the handouts provided at the meeting are attached to the report. The handouts can be obtained in electronic form from the chairman.