Unplanned shutdown of NPP Dukovany
Unplanned shutdown of NPP Dukovany Unit No. 4 for repair of small leakage of purge pipeline
The 30th of March, 2011, dosimetric system SYRAD identified increased value of dimensional activity of aerosols in room B 201/2 at the reactor unit No. 4. Value was very low, nevertheless spectrometric analysis showed small leakage in primary circuit. Operator decided in accordance with this analysis to decrease reactor power for performing of visual control of equipment.
Leakage was identified during visual control – purge pipeline of delivery pipeline of high pressure safety system, external diameter 22mm. Evaluation of leakage was done – maximum 3mm. Measured value will be described immediately after cooling down of primary circuit.
Operator launched cooling down of primary circuit immediately after identification of leakage and started administrative preparation for repair activities. Performing of reparation and technique of reparation were agreed by the Regulator. Expected time of reparation is Saturday, the 2nd of April, afternoon. Start-up process is conditioned by successful pressure test of primary circuit. The event will be fully assessed by Operational Experience Feedback System.