INES-event
INES 2

Loss of reactor coolant system inventory

With the unit shut down and reactor coolant system (RCS) at 295 deg. F (146 C) and 350 psia (2,413 kPa), plant operators were preapring to place one train of shutdown cooling into service. When they opened the motor-operated suction valve for the "B" low pressure safety injection pump, indicated pressurizer level decreased from 35% to offscale low, and RCS pressure decreased to 100 psia (689 kPa). Operators closed the pump suction valve to terminate the coolant loss, and tripped the operating reactor coolant pumps due to low RCS pressure. Approximately 5,500 gallons (20,818 litres) of coolant flowed from the RCS to the refueling water storage pool. Pressurizer level was restored after operators manually started one of the high pressure safety injection pumps. The licensee declared an ALERT emergency classification due to this event.
Justification of the rating: This event was rated as level 2 in accordance with Section IV-3.2.1.3 (a) of the 1998 Draft INES User's Manaul, as an event with an actual initiator of possible frequency and safety function operability within operating limits and conditions.

Location: WATERFORD-3
Event date: Sat, 27-11-1999
Nuclear event report
Legenda & explanation