05000305/LER-2009-002
| Docket Number | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition |
| Initial Reporting | |
| ENS 44812 | 10 CFR 50.72(b)(3)(v)(A), Loss of Safety Function - Shutdown the Reactor, 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material |
| 3052009002R00 - NRC Website | |
CONTINUATION SHEET
Kewaunee Power Station 05000305 � 2� OF� 3
Event Description:
On January 28, 2009 with the Kewaunee Power Station (KPS) at 100 percent power, mechanical maintenance notified the control room that two doors [DR] (Door 3 and Door 5) would be opened per procedure MA-KW-MPM-FP-030C, "Dry Test of CO2 System for Hose Reel Stations," Step 5.2.4.a to vent the cardox room (carbon dioxide (CO2) tank [TK] room) during bleeding of the CO2 supply header. This is allowed per procedure OP-KW-AOP-GEN-005, "Barrier Control," step 3.2.20.a, in that doors shall only be held open by an individual without the use of mechanical aids (e.g. chocks or cords). The shift technical advisor (STA) entered the area at 08:34 CST. The STA noticed that the door chock (installed on the door) for Door 5 was in the down position with a mechanic stationed at the door. With the door chock down, Door 5 was inoperable as a steam exclusion boundary between the CO2 storage tank room and safety related 480 volt switchgear [SWGR] rooms. This would render both trains of 480 volt engineered safeguards feature (ESF) busses [BU] inoperable. A high energy line break in the turbine building with Door 5 open would allow steam into the emergency safeguards bus area.
The STA instructed the mechanic to lift the door chock so the door would be able to close on its own. Per the mechanic, the door chock was down for less than 15 minutes. The STA then walked around to Door 3 via the emergency diesel generator [DG] rooms and noticed that a person was also stationed at that door but it was not mechanically blocked open.
KPS Technical Requirements Manual (TRM) ALCO 3.0.9, "Steam Exclusion System," specified that "all required steam exclusion boundaries such as walls, hatches, etc., shall be OPERABLE." Required action A.1 directs that, for an inoperable steam exclusion boundary, "declare all equipment supported by the inoperable steam exclusion barrier inoperable.
In accordance with TRM 3.0.9, all equipment supported by that steam exclusion boundary door was inoperable. Both trains of 480 volt ESF power supplies were inoperable. Technical Specification 3.0.c, "Standard Shutdown Sequence," was entered at the time of discovery and exited when the door chock was removed from the door.
An eight hour Reactor Plant Event Notification (EN#44812) was made at 12:24 CST.
This condition is being reported pursuant to 10 CFR 50.73(a)(2)(ii)(B), as a condition that resulted in the nuclear power plant being in an unanalyzed condition. Additionally, since both trains of emergency safeguards equipment were inoperable, this condition is being reported under 10 CFR 50.73(a)(2)(v), for any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to: (A) Shut down the reactor and maintain it in a safe shutdown condition; (B) Remove residual heat; (C) Control the release of radioactive material; or (D) Mitigate the consequences of an accident.
Event and Safety Consequence Analysis:
The steam exclusion system aids in the mitigation of a high-energy line break outside of containment. The primary functions of steam exclusion are to provide suitable environmental conditions for needed equipment operation, and a habitable environment for personnel in areas outside of containment which may require access should a high energy line break occur.
If a steam exclusion boundary is inoperable, a barrier that may be credited with protecting a supported component or system is no longer capable of providing that protection. This condition requires that all �NRC FORM 366A (9-2007) PRINTED ON RECYCLED PAPER NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (9-2007) LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
Kewaunee Power Station 05000305 O 3O OF 3 equipment supported by the inoperable steam exclusion barrier be immediately declared inoperable unless an evaluation has been performed to determine that required equipment supported by the inoperable steam exclusion barrier is OPERABLE.
By design, steam exclusion doors are allowed to be opened for normal ingress and egress. NRC TIA 98-004 stated: "if a barrier, (including a door acting as a barrier) is removed, opened for more than routine ingress and egress, or otherwise made incapable of performing its design function, the equipment protected by the barrier should be declared inoperable..." Routine ingress and egress has been defined by the site as equipment necessary to support the normal maintenance, surveillance and operation of the plant, subject to the following conditions: Doors shall not remain open in excess of one hour; and, doors shall only be held open by an individual, without the use of mechanical aids (e.g. chocks or cords).
Since Door 5 was held open with a mechanical aid, the door was open for other than routine ingress and egress. Therefore, both trains of ESF equipment were inoperable.
The door was blocked open for less than 15 minutes. The probability of a steam line break during that short period of time is very low. Therefore the event was of very low risk significance.
Cause:
Maintenance procedure MA-KW-MPM-FP-030C, "Dry Test of CO2 System for Hose Reel Stations," does not restrict or provide detail as to how the door is to be held open, allowing interpretation.
Corrective Actions:
A walk down by operations of all steam exclusion doors found no other doors with a door chock installed.
The chock on Door 5 was removed.
Seven maintenance procedures and two operations procedures were identified for changes to align with the requirements as stated in OP-KW-AOP-GEN-005, "Barrier Control," step 3.2.20.a, in that doors shall only be held open by an individual without the use of mechanical aids (e.g. chocks or cords).
Similar Events:
Safety Systems NRC FORM 366A (9-2007) PRINTED ON RECYCLED PAPER