3.1 INSPECTION AND ASSESSMENT ACTIVITIES AT NUCLEAR INSTALLATION:
JE EBO, V-1 NUCLEAR POWER PLANT
EBO V-1 NPP is equipped with two reactors of WWER 440, V-230 type and was commissioned in 1978-1980 as one of the last NPP with this reactor type. Safety enhancement on V-1 NPP have been performed continuously since 1990, with the aim to improve safety of this NPP to a level required by UJD which is in compliance with the IAEA recommendations. Planned activities in the program of safety enhancement will be completed in 1999 for unit 2 and in 2000 for unit 1. The current status of EBO V-1 NPP is characterized by stable energy operation utilizing both units for so called "tertiary regulation" of capacity supplied to the power grid. On both units overhaulings were performed during the extended outages based on a long-term maintenance plan.
During the extended outage on unit 1 of EBO V-1 NPP the works of gradual reconstruction planned for 1998 were realized. The system of automatic reactor protection system was installed and its demonstration operation was launched in the so called "open loop" mode (i.e. without sending signal to actuators), modifications on the system of (super)emergency feed water system of steam-generators were completed, modifications in control (revolutions and excitation) were made and new electric protections were installed on 4 diesel--generators, the system of measuring outlet coolant temperature from fuel assemblies was replaced, modifications of the venting systems were made, partial modifications of electric distribution lines of 6 kV and 0.4 kV were made, etc.
Assessment activities of UJD in 1998 were focusing mainly on activities related to preparation and implementation of a gradual reconstruction of safety systems on EBO V-1 NPP. One of the most demanding of technical knowledge was the new automatic reactor protection system and related modifications on instrumentation of reactor control system. This programmable system integrates the following functions: automatic reactor scram, control of safety systems, system of measuring the neutron flux, reactor power limitation system, actuation of emergency core cooling system, start up of a diesel generator and load sequencer , reactor protection for case of steam generator pipe break and reactor power control system. Other assessment tasks, characteristic by their high demand on UJD inspectors, were mainly:
Inspection activity of UJD at EBO V-1 NPP, besides planned inspections, focused mainly on control related to implementation of requirements requested by UJD for the program of safety improvements and by meeting these UJD conditioned further operation of both units of EBO V-1 NPP. In this connection and before the start up of unit 1 after the extended outage a team inspection was carried out. Based on positive status an approval was issued for operation of unit 1 of EBO V-1 NPP for the 18th fuel cycle.
Inspection activity on unit 2 of EBO V-1 NPP focused on implementation of safety improvements, on in-service inspection programme, on quality assurance at implementation of modifications, on verification of compatibility of parameters of equipment and systems status with safety analysis report, on pre-operational and operational testing, and also on control of meeting the imposed measures from the previous resolutions and protocols from UJD inspections. With regard to the large scope of works realized during the extended outage, start up of unit 2 and with that also finishing the inspection before start-up, will be realized in 1999. The analysis of inspections findings shows that there were no serious shortcomings. The most significant are those shortcomings in meeting the program of quality assurance by the contractor of gradual reconstruction, non-adherence to rules of clean assembly on the equipment of the primary circuit, incomplete technical documentation and operating instructions prior to commissioning of EBO V-1 NPP units after the extended outage.
Certain new facts were brought by the inspection activities of the authority which UJD started to perform based on competencies according to the new Act No. 130/1998 Coll. Based on inspections at construction tests on classified safety important equipment it can be stated that UJD found gross lack of preparedness for construction tests by the relevant supplier organizations, as practically in none of the cases it would be possible to confirm success of the construction test at the first attempt. Shortcomings were mainly in incomplete technical documentation. Based on the overall evaluation results of the status of both the equipment and personnel, including assessment of operational events, and taking in regard the favorable development of operational indicators (see Fig. 1, 2 and 3), as well as satisfactory results of inspection activity, in 1998 UJD evaluated the operation of both units of EBO V-1 NPP as safe and reliable .