Two items from this morning’s Nuclear Regulatory Commission’s Event Notification Report:
1. Last November, the Palo Verde nuclear power plant reported a control room alarm that indicated low fluid pressure in a hyrdaulic accumulator serving a main steam isolation valve associated with the Unit 1 reactor. A plant operator was dispatched to perfom a pre-charge check of the accumulator, procedure that returns hydraulic fliud from the accumulator to a vented tank that serves as a fluid reservoir. During this check, the fliud reservoir associated piping were damaged by the rapid expansion of nitrogen gas that had entered the system via a leak across an accumulator o-ring. As a result of the damage, the steam isolation valve and associated piping were declared inoperable.
Upon further review, Palo Verde determined yesterday that the incident should have been characterized as an explosion within the Protected area, and that an Emergency Condition should have been declared. Palo Verde may not be timely, but they are thorough.
2. A licensed employee working at the Cook nuclear power plant violated the facility’s Fitness for Duty policy. Cook gave no indication whether the employee failed a drug or alcohol screening or whether he failed to show up for a scheduled test. The employee’s plant access has been suspended, and Cook indicated that the worker “will be evaluated under for-cause FFD testing,” which makes it sound as if the employee were visibly impaired or refused testing.