Safety improvement measures

Safety improvement measures

   The safety of nuclear power plants refers not to a static term. It means that safety, safety systems and safety-related technological elements are continuously re-evaluated on the basis of recent international operational experiences and research achievements, with their findings being taken into consideration by plant operators. In addition, licensing authorities regularly review the safety-related findings and factors of nuclear power plants, and require the lessons learnt from safety reviews to be presented in reports during periodic safety reviews.

During a Periodic Safety Review (PSR) the following have to be proved:

• The level of safety of the nuclear power units is no worse than it was when the operating licence was issued;
• The actual condition of the nuclear power units shall be estimated taking into consideration both ageing and wearing, as well as all on-site and off-site factors that affect the safe operation of the nuclear power plant;
• During the review the actual characteristics of the facility shall be compared with the recent up-to-date requirements considered in international practice, and any deviations shall be identified.
• Any risk factors detected shall be classified and a programme of safety improvement measures shall be developed for their management.

   The first such review was performed for Units 1 and 2 in 1995-96 and for Units 3 and 4 in 1998-99. In both cases a review report of 7000 pages was submitted to the nuclear regulatory authority. In 1997 the Nuclear Safety Directorate of the Hungarian Atomic Energy Authority (HAEA NSD) renewed the permanent safety operating licence for Units 1 and 2 with some conditions until 31 December 2008. The review report of Units 3 and 4 was examined in 2000 and the permanent safety operating licence of these two units was renewed until 31 December 2010.


   Since an overall safety review is performed once every ten years and the renewed operating licences will expire on the above-mentioned dates, the second periodic safety review of the Paks NPP units was carried out in 2006-2007.  During this review the actual condition of safety was re-evaluated according to the relevant recent international and national requirements, and was reported in a document of several thousand pages. This report was considered by HAEA NSD at the end of 2008. The permanent safety operating licence of Units 1 and 2 has been renewed with the requirement that appropriate measures be taken by the end of the design operating lifetime, namely end-2012 and end-2014 respectively.

   As can be seen, after a periodic safety review nuclear power plants can be issued an operating licence for further operation if the lessons learnt from the analyses performed with recent methods are implemented in the form of real measures, modifications and modernization of the systems. These are the safety improvement measures described below.