05000237/LER-2000-004-01, Supplement to Reactor Scram Due to a Failure to Close Current Transformer Knife Switches Following Maintenance
| ML022170564 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/26/2002 |
| From: | Hovey R Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RHLTR: #02-0042 LER-00-004-01 | |
| Download: ML022170564 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv), System Actuation |
| 2372000004R01 - NRC Website | |
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Exelkns.
Exelon Generation Dresden Generating Station 6500 North Dresden Road Morris, IL 60450-9765 Tel 815-942-2920 www.exeloncorp.com Nuclear 10 CFR 50.73 July 26, 2002 RHLTR: #02-0042 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Unit 2 Facility Operating License No. DPR-1 9 NRC Docket No. 50-237 Subject: Licensee Event Report 2000-004-01, "Supplement to Reactor Scram Due to a Failure to Close Current Transformer Knife Switches Following Maintenance" Enclosed is Licensee Event Report 2000-004-01, "Supplement to Reactor Scram due to a failure to close Current Transformer knife switches following maintenance," for the Dresden Nuclear Power Station (DNPS). This condition is being reported pursuant to 10 CFR 50.73 (a)(2)(iv), which requires the reporting of any event or condition that resulted in a manual or automatic actuation of any engineered safety feature (ESF), including the reactor protection system (RPS).
Corrective Actions include:
The Nuclear Operations Analysis Department (NOAD) Manager and DNPS NOAD First Line Supervisors were held accountable and disciplinary actions were taken in accordance with station policy.
NOAD reinforced management expectations as delineated in procedure MM-AA-7001, "NOAD Management Expectations."
Developed and implemented an action plan that addressed NOAD failure to instill and enforce management standards, policies and administrative controls.
July 26, 2002
-. U.S. Nuclear Regulatory Commission Page 2 If you have any questions, please contact Bob Rybak, Regulatory Assurance Manager at (815) 416-2800.
Respectfully, R. J. Hovey Site Vice President Dresden Nuclear Power Station Enclosure cc:
Regional Administrator - NRC Region IlIl NRC Senior Resident Inspector - Dresden Nuclear Power Station
Abstract
On November 30, 2000, with Unit 2 in Mode 1 at 100% reactor power, Nuclear Operational Analysis Department (NOAD) and Sub Station Construction (SSC) personnel entered the 345Kv yard to perform work on the Oil Circuit Breaker (OCB) 2-7 circuit breaker, which was Out Of Service (OOS). To start the evolution, SSC personnel opened knife switches located in the upper portion of the OCB cabinet, per their approved procedure. Shortly thereafter, NOAD personnel opened 12 current transformer cutout knife switches. This was performed without procedure and resulted in a lack of configuration control to assure recovery of the switches following maintenance. SSC personnel remained unaware that this was performed for the duration of the event. At the conclusion of work for the shift, NOAD utilized inappropriate nomenclature when asking SSC personnel whether the knife switches had been re-closed. This resulted in the OCB being returned to service with the knife switches inappropriately positioned (open) causing a Unit 2 reactor scram from full power when the Operators attempted to close the OCB.
The root cause, specific to the tripping of the 345Kv OCBs and reactor scram, was determined to be insufficient adherence to management standards, policies, and administrative controls by NOAD personnel. Corrective actions included: the NOAD Department Manager and DNPS NOAD First Line Supervisors were held accountable and disciplinary actions were taken in accordance with station policy; NOAD reinforced management expectations as delineated in procedure MM-AA-7001, "NOAD Management Expectations;" and development and implementation of an action plan that addressed NOAD's failure to instill and enforce management standards, policies and administrative controls.U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 COMMISSION EXPIRES 07/31/2004 (7-2001)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6 PAGE (3)
YEAR SEQUENTIAL REVISION Dresden Nuclear Power Station Unit 2 05000237 NUMBER NUMBER 2000 004 01 2 of 3 (If more space is required, use additional copies of NRC Form 366A)(17)
A.
Plant Conditions Prior to Event:
Unit: 02 Event Date: 11-30-2000 Event Time: 1550 CST Reactor Mode: 1 Mode Name: Run Power Level: 100 percent Reactor Coolant System Pressure: 1000 psig B.
Description of Event
This condition is being reported pursuant to 10 CFR 50.73 (a)(2)(iv), which requires the reporting of any event or condition that resulted in a manual or automatic actuation of any engineered safety feature (ESF), including the reactor protection system (RPS).
At 0710 hours0.00822 days <br />0.197 hours <br />0.00117 weeks <br />2.70155e-4 months <br />, one of the SSC crews was assigned the task of performing a lubrication and preventative maintenance inspection of the 345Kv 2-7 OCB. Additionally, they were told that NOAD would be doing testing of the bushings on the circuit breaker, looking for the location of hot spots, after which SSC would be performing cleaning of the bushing to correct the problem.
At approximately 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br />, the SSC Crew Leader told the SSC crew that he would be leaving to sign out the key to the 345Kv yard and obtaining approval to start work from the Operations department. He further stated that the crew should collect the supplies needed to perform the tasks at the OCB.
At approximately 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br />, the SSC Crew Leader returned from the station and unlocked the 345Kv yard for access. Arriving at the 345Kv OCB 2-7, the Crew Leader performed a walkdown of the OOS that was previously hung by Operations. A briefing had been held with the SSC crew, which was predominantly focused on personnel safety around energized equipment. Based on the interviews performed, no formal Heightened Level of Awareness (HLA) briefing or risk assessment had been performed regarding the scope of work being performed.
A SSC mechanic began the lube and preventative maintenance activity by opening the knife switches associated with supplying AC and DC power to various components within the OCB cabinet. (These switches were in the upper left portion of the cabinet.) Once the knife switches were opened, SSC personnel stepped away and NOAD personnel approached the cabinet, referenced electrical drawings, and proceeded to open 12 current transformer knife switches located in the lower left side of the cabinet to allow hot spot testing of the OCB. SSC personnel did not observe the opening of these switches and remained unaware of this action for the duration of the event sequence.
With the knife switches aligned to support performance of testing of the OCB bushings, testing began on the first of six OCB bushings.
At approximately 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br />, with all bushings in an assembled state, the SSC closed in the knife switches they had previously opened, collected all tools, dismantled the testing equipment, and loaded up their truck. As they walked away from the OCB, one of the SSC workers asked his Crew Leader if the knife switches had been re-closed. The Crew Leader stated that he personally closed the switches. The SSC worker returned to the OCB 2-7 cabinet, opened the door and verified that the knife switches in the upper left portion of the panel were closed.
The SSC crew returned to the SSC building at 1445 hours0.0167 days <br />0.401 hours <br />0.00239 weeks <br />5.498225e-4 months <br />. One of the NOAD personnel, who was performing labeling in the 345Kv relay house, was called because his vehicle was within the fenced area. He was told that heU.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 COMMISSION EXPIRES 07/3112004 (7-2001)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
FACILITY NAME (1)
DOCKET NUMBER (2)
ER NUMBER (6 PAGE (3)
YEAR SEQUENTIAL REVISION Dresden Nuclear Power Station Unit 2 05000237 NUMBER NUMBER 2000 004 01 3 of 3 (If more space is required, use additional copies of NRC Form 366A)(17) needed to remove his vehicle because the SSC personnel were leaving for the day and the yard was going to be locked up. The NOAD individual asked whether all the knife switches had been re-closed. The SSC Crew Leader responded that they were closed.
SSC contacted Operations and Bulk Power Operations, stating that they were off the equipment and that it was ready to have the OOS cleared and OCB closed in. Operations dispatched a High Voltage Operator and Operations Supervisor, who cleared the OOS. With that completed, Bulk Power Operations contacted the Control Room Nuclear Station Operator (NSO) and directed him to close in the 345Kv 2-7 OCB. At 1550 hours0.0179 days <br />0.431 hours <br />0.00256 weeks <br />5.89775e-4 months <br />, Operations closed in the 345Kv OCB 2-7 circuit breaker from the 902-8 panel, at which time Unit 2 concurrently scrammed on load reject.
C.
Cause of Event
The root cause, specific to the tripping of the 345Kv OCBs and reactor scram, was determined to be the failure of NOAD personnel to maintain proper Configuration Control to approved NGG and station methodologies due to improper verification practices. (NRC Cause Code A)
D.
Safety Analysis
The safety significance of this event was limited to the fact that it was a challenge to Operations, as is every situation involving a need for prompt diagnosis and decision during a trip of the reactor. Plant equipment response was per design and required no operator action. All Emergency Core Cooling Systems and required plant systems were available and responded correctly.
Based upon this evaluation, the safety significance of this event has been determined to be minimal.
E.
Corrective Actions
The NOAD Department Manager and DNPS NOAD First Line Supervisors were held accountable and disciplinary actions were taken in accordance with station policy.
NOAD reinforced management expectations as delineated in MM-M-7001.
Developed and implemented an action plan that addressed NOAD failure to instill and enforce management standards, policies and administrative controls.
F.
Previous Occurrences
None G.
Component Failure Data
N/A