Plant start up with too low levels in the borated water storage tanks
Wednesday, October 24, 2001
In the course of the investigations following the INES 2 event “Boron concentration below specifi-cation in borated water storage tanks of 3 out of 4 ECCS trains” the licensee detected on October 22, 2001, that the plant was started up after the refueling outage on August 10, 2001, with too low levels in all borated water storage tanks. The specified level in the tanks is > 12.6 m. The level indications showed 12.5 m, 10.8 m, 10.6 m and 9.3 m, respectively. Due to the technical specifi-cations the borated water storage tanks must be filled to the specified level if the primary circuit pressure exceeds 10 bars. The plant personnel ignored the related alarms in the control rooms, so that the filling of the tanks was only performed on August 12, 2001, with the reactor at hot stand-by condition (reactor subcritical).