05000316/LER-2002-002
| Donald C. Cook Nuclear Plant Unit 2 | |
| Event date: | 02-12-2002 |
|---|---|
| Report date: | 04-12-2002 |
| 3162002002R00 - NRC Website | |
2002 -- 02 _ 00 17. TEXT (If more space is required, use additional copies of NRC Form (366A) Conditions Prior to Event Unit 1 - 100 percent power Unit 2 - MODE 6
Description of Event
On February 12, 2002, Technical Specification (TS) 3.9.4.c was violated when the 100 PSI Control Air to Containment Control Air Header #2 Train 'B' Containment Isolation Valve, 2-XCR-101 [EIIS:LK:SHV], was stroked open during core alterations with open test connections on both sides of the valve, one inside containment and one outside. This configuration provided direct access from the containment atmosphere to the outside atmoshere.
A post event investigation of this incident revealed that on January 20, 2002, as part of preparation for 10 CFR 50 Appendix J, Type B & C leak rate testing of Containment Isolation Valve 2-XCR-101, the # 1 and # 2 Containment Control Air headers were cross-tied with air hose jumpers. The purpose of cross-tying the Control Air headers was to allow the # 2 headers to be fed by the # 1 headers while the Containment Isolation Valve for the # 2 headers (2-XCR-101) was isolated from the system for leak rate testing. Jumper installation was performed by Attachment 5 of the B & C Leak Rate procedure, but was not logged in the Proceduralized Temporary Modification Log in the control room as required by the Temporary Modification Procedure. The cross-tie jumpers were left in place to support scheduled maintenance activities on the control air valve 2-XCR-101.
On January 26, 2002, in further preparation for Type B & C leak rate testing of valve 2-XCR-101, Lineup Sheet 1 of the procedure isolated valve 2-XCR-101 from the rest of the Control Air System by closing the upstream shut off valve and the downstream shutoff valves for the 50 and 85 psi Control Air Containment Ring Headers. The line-up also opened test connection valves on both sides of valve 2-XCR-101, one inside containment and one outside. This alignment was left in place, via a clearance, to support maintenance activities on valve 2-XCR-101. At the time, refueling integrity for Penetration CPN-74 was established by using an Option from the Refueling Integrity Procedure 02-OHP-4030.STP.041 which consisted of closing valve 2-XCR-101.
On February 9, 2002, when refueling integrity was reestablished via Procedure 02-OHP-4030.STP.041, the procedurally designated preferred method (Option) was used to establish refueling integrity for penetration 2-CPN-74. This method of demonstrating refueling integrity involves confirming that the penetration is actively pressurized by control air. By being pressurized, the penetration would not provide direct access from the containment atmosphere to the outside atmosphere.
Subsequently, this method of verification was determined to be ineffective if the control air headers are cross-tied. Another method of establishing refueling integrity, one which closes 2-XCR-101, or otherwise closes off the penetration, should have been used.
On February 12, 2002 during core alterations maintenance activities on valve 2-XCR-101 stroked the valve open with test connections open on both sides of the penetration thus creating an actual path from the atmosphere inside containment to the atmosphere outside containment.
Technical Specification (TS) 3.9.4.c requires, in part, that each containment building penetration providing direct acccess from the containment atmosphere to the outside atmoshere be either closed by an isolation valve, blind flange, manual valve, or equivalent. During the time maintenance stroked valve 2-XCR-101, a breach of refueling integrity resulted. This breach of integrity is prohibited by TS and is therefore reportable in accordance with 50.73(a)(2)(i)(B).
2002 02 � 00 17. TEXT (If more space is required, use additional copies of NRC Form (366A)
Cause of Event
The apparent cause was determined to be ineffective procedural control (02-OHP-4030.STP.041). The preferred method for establishing refueling integrity for 2-CPN-74 in the procedure does not consider the possibiltiy that the control air ring headers may be cross-tied.
A contributing cause was that the installation of containment control air header cross-tie jumpers was not documented in the Proceduralized Temporary Modification Log on January 20, 2002.
Analysis of Event
The Bases for TS 3.9.4.c states that the requirements on containment building penetration closure and operability ensure that a release of radioactive material within the containnment will be restricted from leakage to the environment. The operability and closure restrictions are sufficent to restrict radioactive material release from a element rutpure based upon the lack on containment pressurization potential while into refueling mode.
The loss of refueling integrity was limited to the time it took to cycle valve 2-XCR-101 open and closed. Therefore public health and safety was not impacted as a result of this event.
Corrective Actions
Upon discovery that the preferred method used to maintain refueling integrity for 2-CPN-74 was ineffective, another method from procedure 02-OHP-4030.STP.041 was initiated and valve 2-XCR-101 was visually confirmed to be intact and closed.
The Temporary Modification Log was reviewed to determine if other Temporary Modification were un-logged. The containment control air cross-tie jumpers were documented in the log at that time.
The refueling integrity procedures will be revised to ensure that the methods used to establish refueling integrity provided for Penetrations CPN-74 and CPN-29 recognize that the Containment Control Air headers may be cross-tied and check whether the jumpers are in place. The completion date for this revision is scheduled prior to its usage during the next refueling outage.
Unit 1 and Unit 2 Type B and C Leak Rate Testing procedures will be revised to ensure that steps are added for documenting the placement of the containment control air header cross tie jumpers in the Proceduralized Temporary Modification Log. The completion date for this revision is scheduled prior to its usage during the next refueling outage.
Previous Similar Events
0234-203, Unit 2 B & C Leak Rate Testing, which violated refueling integrity while fuel movement was in progress.
A refueling tag was inadvertently lifted and the component re-positioned. This was a human performance error.
The corrective action associated with LER 316-2002-001-00 would not have prevented this incident from occurring.