05000336/LER-2005-001

LER-2005-001,

Docket Number
Event date:	02-07-2005
Report date:	03-17-2005
3362005001R00 - NRC Website

1. Event Description On 2/7/05, at approximately 1254 hours0.0145 days <br />0.348 hours <br />0.00207 weeks <br />4.77147e-4 months <br />, with Unit 2 at 100% power, it was identified that the manual operator on Unit 2 valve 2-SI-306, Shut Down Cooling (SDC) [BP] Total Flow Control Valve, was not pinned as intended and required by Technical Specification 4.5.2.b. The pin was found inserted in a location between the handwheel shaft and the valve shaft (a dead space), and thus the valve and handwheel were in fact, not attached. This resulted in the manual operator not being engaged (not attached to the valve shaft).

This event/condition is being reported pursuant to 50.73(a)(2)(i)(B), related to operation in a condition prohibited by the Technical Specifications.

2. Cause The cause of this event was determined to be inadequate procedure guidance as to the actual required location of the pin. The intent of Steps 4.18.7f - 4.18.7h. of OP 2310, Shutdown Cooling System [AB], are to place 2-SI-306 in manual control. The last time the pin for the manual operator on 2-SI-306 was installed, it was installed incorrectly. The valve was not left in manual control since the pin did not attach the manual handwheel to the valve plug.

3. Assessment of Safety Consequences The primary purpose of the SDC system is to remove heat from the core during plant cooldown and refueling operations. The SDC system also serves as part of the emergency core cooling system by providing low-head high flow safety injection to the Reactor Coolant System (RCS) during accident conditions. Valve 2-SI-306 is the throttle valve in the common discharge header.

Valve 2-SI-306 was always open (its accident position). The re-pinning of the manual operator on 2-SI-306 did not move the valve position, it simply engaged the manual operator. There was no power to the valves' solenoid and the air to the valve was isolated, and since the valve fails open, 2-SI-306 was always in its accident position (open). The pinning of the manual operator is an additional layer of defense that would prevent the valve from closing should the spring in the air actuator somehow fail (or some other issue), and the valve started to move due to vibration or flow; the mechanical advantage of the manual operator would prevent the valve from closing. It is noted that the manual valve position indicator does not indicate actual valve position, unless the pin is inserted (correctly), connecting the manual handwheel to the valve plug. Consequently, this event is considered to be of very low safety significance.

4. Corrective Action As a result of this condition, the following action was performed to restore compliance.

• The valve handwheel was unlocked, rotated until the hole in the valve sleeve lined up with the valve shaft, the pin was inserted, and the valve handwheel was relocked.

An investigation was conducted and corrective actions have been or are being addressed in accordance with the Millstone Corrective Action Program.

• Unit procedures will be revised, as required, strengthening the guidance as to the final pin position location to ensure the manual operator on 2-SI-306 is engaged to the valve plug.

5. Previous Occurrences A review of the Production Maintenance Management System and past Condition Reports, as well as discussions with Millstone valve experts did not identify any similar events.

OE was reviewed, and one CR was identified where a valve was intended to be pinned, and it was identified that an operator forgot to pin the affected valve, a different issue than this one.

Energy Industry Identification System (EDS) codes are identified in the text as [XX].