On both units of NPP V-1 Bohunice during the outages of units UJD performed a continuous control of meeting the programs of in-service inspection, as well as assessment of results of non-destructive tests. Results of in-service inspection were assessed for the relevant unit by a commission for assessment of in-service inspection, constituted by the operator. Also a representative of UJD took part in negotiations of the commissions. The status in the field of integrity can be assessed as follows:
On both units the overhauls were performed and in-service inspection are in compliance with the in-service inspection programs for 1999. During these controls no new serious indications which would require extraordinary solutions were found. Besides that UJD assessed program and results of pre-complex and complex testing of reconstructed refueling machine of NPP V-1 Bohunice.
Based on the request from UJD, every year the operator makes an assessment of residual life of major components of the NPP, and that is based on the operating history of the relevant unit during the campaign. The average material fatigue of major components in both units is very favorable and is not a limiting factor for further operation.
In 1999 also the relevant parts of POSAR were assessed, affected also by realized design changes. These are mainly safety analyses in connection with changes on the system of mitigation and accident localization. These modifications are also related to analyses of beyond design accidents, including their impact on the population. Analyses of generation, distribution and hydrogen burning in conditions of severe accidents on units NPP V-1 Bohunice after their reconstruction were assessed. Another significant part of the assessment activities of UJD at NPP V-1 Bohunice was assessment of operational events. During 1999, according to the methodology approved by UJD, during operation of both units there were 54 events in total recorded, of which 28 were classified as level 0. The total number of operational events at NPP V-1 Bohunice in 1999 compared to 1998 has increased, and also the number of actuations of reactor automatic protection (i. e. scrams). At NPP V-1 Bohunice there were 5 actuations, one on Unit 1 and four on Unit 2.
In 1999 these events, important from the safety aspect, were mostly caused by human factor. The staff made mistakes mainly when working with equipment on which there had been design changes made within the program of unit reconstruction. None of the events were classified by level 1 or higher on the INES scale.
During 1999 there was not a violation of limits or conditions of safe operation on NPP V-1 Bohunice. In the course of operation of NPPs, UJD monitors development of certain indicators according to which it is possible to evaluate the safety culture, or reliability of NPP operation. Such indicators are: the number of operational events, number of reactor scrams, collective dose on personnel, and others. Statistical overview of the number of operational events at NPP V-1 Bohunice between 1993 and 1999 and their categorization according to INES scale: