The stress tests of nuclear power plants (NPPs) in Slovakia were launched on 1 June 2011, as agreed by the EC and the ENSREG Group. All the Slovak NPPs in operation, that is Bohunice V-2, Mochovce 1&2, and a power plant under construction, Mochovce 3&4 underwent the testing. The schedule of testing was divided into several phases.
In the initial phase Slovakia submitted its National Report on 30 December 2011 on the results of the stress tests carried out on the Slovak NPPs to the Secretariat for the stress tests, the function of which is performed by the Joint Research Center in Petten, the Netherlands. However, this did not conclude the process of the stress tests, but continued with the phase of international evaluation of results, which was organized in three steps.
From 1 until 20 January 2012 there was a so called desktop review, during which all the participating national regulators of the EU countries, as well as the European Commission (EC) itself, had the possibility to study the National Reports as submitted and to formulate questions for 17 countries, which performed the stress tests. Slovakia received 90 questions regarding its National Report, to which ÚJD SR in cooperation with SE, a. s. prepared written answers.
Topical Peer Review
The second step of the assessment was a topical peer review, which took place from 5 to 22 February 2012 at the premises of the EC in Luxembourg. As the name suggests, the review was divided into three main topics, namely:
Earthquakes and extreme natural external conditions,
Complete loss of power supply and loss of ultimate heat sink,
Management of beyond-design (severe) accidents.
For each area, all the EU countries had the right to nominate one expert, who participated in the assessment. Slovakia was represented by Mr. Mišák from ÚJV Řež, Mr. Uhrík and Mr. Rovný from ÚJD SR. Together with the representatives of the EC, there were nearly 90 experts participating in the topical peer review. Countries that carried out the stress tests, presented the main results of the evaluation. At the same time they responded to the most important questions that were received during the previous phase (Desktop Review) and answered direct questions from the experts present. The outcome of this assessment was a draft report from the assessment for each participating country.
Country peer review
Country Reports have been finalized during the last phase of the stress tests, which took place in March 2012 in each of these countries (the Country Peer Review). An international team of experts (from Germany, Bulgaria, Lithuania, France, Hungary, Italy and the EC), which was tasked to verify the declared results of the stress tests directly in the country and in particular directly at the NPP, was in Slovakia from 26 till 29 March 2012.
During these days the representatives of ÚJD SR and SE, a. s. answered the questions of foreign assessors, who verified the declared claims also on the operating Units 1&2 of NPP Mochovce and on Units 3&4 of NPP Mochovce that are under construction. Attention was paid to seismic resistance of safety relevant structures, systems and components, measures against flooding the power plant site, the availability of standard and non-standard inventory of coolant in the power plant, power supply options from various sources, the condition of acu batteries and other important aspects of safety of operation.
Based on the findings the team of assessors finalized the assessment report, which after the whole process is completed, will be published together with other reports of other EU Member States. In addition to a brief summary of facts relating to the legislative requirements, project and organizational measures related to three areas monitored, the report also mentions the strengths of NPPs in Slovakia, as well as recommendations for further improvements.
Practicing intervention of the plant fire brigade unit
During the site visit the assessors of the Country Peer Review witnessed practicing of an intervention by the plant fire brigade unit, which in just a few minutes from announcing the request, compiled the technical equipment into a configuration, which can supply feed water to the steam generators with no power supply to the power plant site.
EC Final Report from the Peer Review
On 26 April 2012 the EC and the ENSREG group issued a Final Report of EC - Peer Review Report of the stress tests performed on the European nuclear power plants. ENSREG and the EC in their joint declaration stated that: "Following the principle of continuous improvement of nuclear safety the stress tests identified specific improvements. Both the final Peer Review Report, and the Country Reports contain very practical recommendations aimed at achieving concrete improvements.
The overall report highlights four main areas for improvement that will be reviewed throughout Europe:
- WENRA recommendations based on the best available expertise in the EU on the assessment of natural risks, taking into account the IAEA guides
- Emphasizing the importance of the Periodic Safety Review
- Implementation of accepted measures to protect reactor integrity
- Minimizing accidents caused by natural factors and limiting the consequences of such accidents
Additional Review of NPPs
Additionally, expert visits were called and a review of selected nuclear power plants was conducted by these experts (FR -3, UK -3, DE -1, ES – 1, CZ – Temelín), the results of which should be available by the end of September 2012.
Final step by the EC
Based on all the information gathered the representatives of the evaluation committee of the EC will prepare Final Report from the stress tests of nuclear power plants covering all relevant countries. The report will be publicly available and will be presented to the European Parliament.