05000455/LER-2013-002
| Byron Station, Unit 2 | |
| Event date: | 09-18-2013 |
|---|---|
| Report date: | 11-18-2013 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4552013002R00 - NRC Website | |
A. Plant Condition Prior to Event Event Date/Time: September 18, 2013 / 1555 hours0.018 days <br />0.432 hours <br />0.00257 weeks <br />5.916775e-4 months <br /> CST Unit 2 - Mode 1 - Power Operations, Reactor Power 100 percent Reactor Coolant System [AB]: Normal operating temperature and pressure.
B. Description of Event
On September 18, 2013, the plant was in Mode 1 with reactor power at 100 percent. At 1555, an unqualified valve diaphragm was identified to have been installed on Air Operated Valve 2RE9160A, Reactor Coolant Drain Tank to Waste Gas (GW) Compressor Inside Containment Isolation Valve, during the September 2011 refuel outage.
The 2RE9160A valve was immediately declared inoperable based on the unqualified valve diaphragm. The associated containment penetration was isolated per the required actions in Byron Technical Specification (TS) 3.6.3, Condition A. Since the condition existed for longer than allowed by TS 3.6.3 (Containment Isolation Valves), Required Action A.1, i.e., for more than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, this is a reportable condition per 10 CFR 50.73 (a)(2)(i)(B) as any event or condition that was prohibited by Technical Specifications.
In January 2011, Maintenance Work Planning had prepared work packages for the 2RE9160A (Containment Isolation Valve — inside containment) and 2RE9160B (Containment Isolation Valve — outside containment) valves. A generic material request document was utilized to select the appropriate parts for the work order. This generic material request contained both the environmentally qualified diaphragm and unqualified diaphragm, which the work planner selected based on the valve application. The planner started work on the 2RE9160B diaphragm valve work instructions initially, which is an outside containment diaphragm valve. The planner selected the correct diaphragm for use outside containment. The planner then proceeded to work on 2RE9160A work instructions. The planner incorrectly selected the same diaphragm model for 2RE9160A as he had for 2RE9160B. The 2RE9160A valve is located inside the containment and requires an environmentally qualified diaphragm for that application.
The error was attributed to assumptions made by the Maintenance Work Planner. The planner selected the same diaphragm model as the previous work package, which had just been prepared. The planner assumed since both valves were on the same vender valve drawing and on the same site generic material request, either diaphragm model could be used.
The 2RE9160A valve diaphragm was successfully replaced with a qualified part, tested and declared operable on October 11, 2013.
C. Cause of Event
The cause of the event was an incorrect assumption made by the Maintenance Work Planner to use an unqualified valve diaphragm in a qualified application. The work planner used the 2RE9160B valve work order to create the 2RE9160A work order, not realizing that 2RE9160B is an outside containment valve and 2RE9160A is an inside containment valve. The diaphragm was acceptable for use on the 2RE9160B valve, but not environmentally qualified for use on the 2RE9160A valve.
D. Safety Significance
The 2RE9160A valve is the inside containment isolation valve in the two valve containment isolation configuration. The valve is normally open and has the safety function to close upon receipt of a containment isolation signal. When Operations took action to isolate the penetration, the valve inside containment and the redundant valve outside containment closed without issue. The 2RE9160A inside containment valve passed the as-found local leak rate test. The redundant 2RE9160B outside containment isolation valve was fully qualified, tested and operable for the period the unqualified diaphragm was installed on 2RE9160A.
Based on the above, the significance of this issue is considered low.
E. Corrective Actions
The 2RE9160A valve diaphragm was successfully replaced, tested and declared operable on October 11, 2013. Additionally, Byron personnel are taking actions to update all part identification numbers in material requests in containment to state they are to be selected in containment applications.
F. Previous Occurrences
There have been no previous occurrences of this nature in the previous three years.