CBRN event in Kazakhstan on Sun 23rd March 1997

The reactor was operated at 420 MW and 4 loops. At 17:11 p.m. on 23.03.97 during routine surveillance the operator discovered steam in the steam generator box no. 513/1. The primary circulation pump has been switched off by hand, automatically the reactor power has been decreased to 310 MW and steam generator no. 1 has been drainaged.
At 18:20 p.m. on 23.0397 reactor power had been recovered to 400 MW with 3 loops.
At 10:25 a.m. 24.03.97 reactor power had been recovered to 420 MW with 3 loops.
As inspection showed, there was damage of steam generator recirculation feed water pipeline On 25.03.97 at 9.20 a.m. repair was finished and reactor power had been recovered to 420 MW with 4 loops.
There was no radiation impact on the environment or employees.
Justification: As full safety function was available the event is rated at level 0 as per users manual, Part III.