This report is being made under
10 CFR 50.73(a)(2)(iv)(A) and is not considered a Licensee Event Report.
With Unit 1 at Intermediate Shutdown (226?F and 300 psig), an invalid actuation of the Unit 1 'B' train of the Safety Injection (SI) system occurred at 1804 [EDT] during repair of a broken light socket located on the SI relay cabinet door. Plant systems and components responding to the 'B' train SI signal started and functioned successfully as designed (with the exception of those procedurally rendered inoperable due to the RCS being below 350?F and 450 psig). SI train 'B' was reset and the affected systems were restored to their pre-event configuration.
Specific trains and systems that actuated for train 'B' of SI are described below:
- With the unit at intermediate shutdown, one high head pump was currently running (the two redundant pump controls were in the Pull to Lock position in compliance with Technical Specifications). The 'B' train High Head Safety Injection motor operated valves re-aligned such that the running high head pump provided flow to the RCS Cold Legs from the RWST. During this time a bubble was present in the Pressurizer and the level remained on scale (increased 8%).
- One train of the Control Room Bottled Air System actuated on the Control Room Isolation. The ventilation alignment was restored to normal thereby isolating the Bottled Air System. The system was re-pressurized and restored to an operable condition.
- Auxiliary Feedwater (AFW) Pump motor operated valves opened but no flow was delivered to the Steam Generators since the AFW pumps were in Pull to Lock.
- The 'B' train containment isolation valves closed, isolating the 'B' RHR heat exchanger. However, shutdown cooling was previously being provided by the 'A' RHR train and was therefore uninterrupted. Containment isolation valves were later restored to a normal alignment.
- One train of Auxiliary Ventilation actuated and was restored to normal after the Safety Injection signal was reset.
- Emergency Diesel Generator (EDG) No. 3 started but did not load since its associated Emergency Bus remained energized by offsite power. The EDG was stopped and returned to automatic.
- Reactor Coolant Pumps (RCPs) were stopped due to the closure of the seal water return containment isolation valve.
A root cause evaluation is determining the cause.
The licensee notified the NRC Resident Inspector.
