05000454/LER-2006-003
| Event date: | 09-01-2006 |
|---|---|
| Report date: | 10-30-2006 |
| 4542006003R00 - NRC Website | |
Background
The Spray Additive System is a subsystem of the Containment Spray System [BE] (CS) that assists in reducing the iOdine fission product inventory in the containment atmosphere resulting from a design basis accident. The Spray Additive System consists of one Spray Additive Tank, containing a sodium hydroxide solution, that is Shared by two trains of spray additive flow paths into the CS pumps. The Spray Additive System is governed by Technical Specification (TS) 3.67, "Spray Additive System." If the Spray Additive System is inoperable,-- then Action condition "A" of this TS requires restoration of operability in 7 days.
Otherwise, condition "B" requires Unit 1 (U1) to 1-e Mode 3 in 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 in 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br />.
, B. - of Event:
Cin Friday August 11, 2006, a Non-Licensed Operator (NLC) on day shift rounds identified a leak on a weld on the upstream side of the U1 "A" train Spray Additive Eductor Inlet Header Drain Isolation Valve (i CS043A).
The NLO notified Shift Management and initiated a Corrective Action Program (CAP) Issue Report (IR). The stated that caustic solution appeared to be leaking from the top weld of the valve and the valve body had a caustic film on it. The NLO used a standard IR template for leaks of this nature.
Due- to imprecise verbal communications concerning the issue, it was believed that the leak was from a mechanical joint, and not an ASME class pressure boundary leakage. Consequently, subsequent Shift Management review of the issue failed to properly consider the operability of the system.
Also, subsequent CAP IR committee reviews of this IR also failed to recognize the leak as being an ASME class boundary leakage and its impact on operability of the system. The IR was disposition as a normal work request.
On September 1, 2006, while discussing the repair plan of the leak on 1CS043A at the daily risk meeting, an engineering manager noted the repair plan included welding and challenged the current operability of the system.
At 1930 hours0.0223 days <br />0.536 hours <br />0.00319 weeks <br />7.34365e-4 months <br /> on September 1, 2006, engineering personnel confirmed a through wall weld leak on an ASME code component which rendered the Unit 1 Spray Additive System inoperable. TS 3.6.7, action condition "A" was immediately entered. The weld was repaired on September 2, 2006 and operability restored.
The Spray Additive System should have been recognized as inoperable on August 11, 2006. Consequently, a condition existed that is prohibited by TS in that Action conditions of TS 3.6.7 were not complied within the allowed completion times. This is reportable to the NRC in accordance with 10 CFR 50.73 (a)(2)(i)(b) as an event or condition that is prohibited by the TS.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) Byron Station 0500454 2006 003 (If more space is required, use additional copies of NRC Form 366A)(17)
C. Cause of the Event
The root cause was determined to be a lack of reinforcement by Operations Management of conducting accurate operability reviews of equipment issues.
Additional contributing causes include the generic IR template used for leaks which directs individuals to assume leaks are from a mechanical joint (which most are) and not a through wall leakage; and weaknesses in Shift Management communications.
D. Safety Analysis
This condition had minimal safety consequences. The leak was characterized as a weeping type of leak (i.e., less than 1 drop per 5 minutes). This would have insignificant impact on the amount of caustic delivered to the CS system. The tank level is monitored as a Main Control Board Indication. In addition, given the small size of noted flaw, and the lack of propagation mechanism for a crack to grow larger, a complete severance of drain line is not considered credible. The safety function of CS system was maintained from the time of discovery to the time of repair.
E. Corrective Actions
A systematic methodology will be developed and implemented to improve the effectiveness of cassroom and simulator training for operability determinations on I Rs.
A management standard will be developed and implemented that rewards behaviors associated with operability documentation/verification of that documentation related to equipment IR's.
The IR component leak template will be revised to improve human factoring for placement of operability information at the beginning of the IR with appropriate language to notify the Shift Manager immediately if leakage is from an NON-mechanical joint.
A case study will be developed covering the details of this event and presented in the operator License Operator Continuing Training Program.
F. Previous Occurrences
There have been no previous LER occurrences of this nature at Byron in previous 2 years.