05000244/LER-2013-001
| R.E. Ginna Nuclear Power Plant | |
| Event date: | 04-12-2013 |
|---|---|
| Report date: | 05-31-2013 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition |
| 2442013001R00 - NRC Website | |
I. DESCRIPTION OF EVENT
A. PRE-EVENT PLANT CONDITIONS:
The reactor was in Operational Mode 1 at 100% power, 2235 psig and 574 degrees F.
B. EVENT:
On April 12, 2013, a system engineer performing a walkdown of backflow prevention devices discovered that the check valve that was expected to be found installed in the floor drain in the Intermediate Building Basement had been removed. The check valve was designed as a barrier to prevent the flow of flammable liquid from the Turbine Building Basement to the Intermediate Building Basement where safe shutdown equipment is located.
C. INOPERABLE STRUCTURES, COMPONENTS OR SYSTEMS THAT CONTRIBUTED
TO THE EVENT:
No other inoperable structures, systems, or components contributed to the event. The only issue was the removal of the check valve in the floor drain between Turbine and Intermediate Buildings.
D. DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES:
April 12, 2013, 1010 Engineering personnel discover that a check valve in a floor drain between the Turbine and Intermediate Buildings is no longer installed.
April 12, 2013, 1100 Compensatory actions initiated - fire detector operability verification and an hourly fire watch inspection.
April 12, 2013, 1445 Notification of Unanalyzed Condition, event # 48918 under 10 CFR 50.72(b)(3)(ii)(B).
April 12, 2013, 1500 Plug installed in drain line as compensatory action to prevent flammable liquid from flowing from Turbine to Intermediate Building.
E. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:
None
F. METHOD OF DISCOVERY:
Discovered by system engineer walking down backflow prevention devices.
On-shift Operations Crew initiated a fire detector operability verification and an hourly fire watch inspection as compensatory actions in accordance with TRM.
H. SAFETY SYSTEM RESPONSES:
None
II. CAUSE OF EVENT:
A review of past maintenance history identified that blockage of this line was a concern and a design review identified that the valve type required a significant amount of water to pass flow. Normal or expected water accumulation would not have passed through the check valve, creating a housekeeping concern. Based on the historical information available, it is concluded that the check valve was most likely removed to prevent water accumulation, without sufficient review of the impact on the design or licensing basis. This condition has been evaluated in the site corrective action program. (CR-2013-002437)
III ANALYSIS OF THE EVENT:
This event is reportable under 10CFR50.73(a)(2)(ii)(B), operation in an unanalyzed condition. This check valve is considered a barrier between the Turbine Building and the Intermediate Building. It connects a floor drain from a safety-related area to a sump in an area that contains a large quantity of potentially flammable liquid, i.e. the turbine lube-oil system. A backflow prevention device is required to prevent possible spread of a liquid fire via the drain system. The Ginna Fire Protection Program does not analyze for simultaneous fires in two or more fire areas. Therefore, this condition is reportable under the above criteria.
The effect of flooding has been evaluated and is not considered to be a concern with the missing check valve or with the floor drain plugged.
There were no safety consequences as all safety related systems remained operable during this event.
IV. CORRECTIVE ACTIONS:
A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL
STATUS:
A temporary plug was installed in the affected floor drain to prevent the back flow of flammable liquids from the Turbine Building to the Intermediate Building. This configuration was evaluated to ensure there was no adverse impact on flood mitigation. A replacement valve could not be readily installed.