05000528/LER-2004-003, Unit I, Regarding Manual Reactor Trip - Slipped Control Element Assembly
| ML041950104 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/08/2004 |
| From: | Danni Smith Arizona Public Service Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 192-01144-DMS/SAB/DGM/DFH LER 04-003-00 | |
| Download: ML041950104 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 5282004003R00 - NRC Website | |
text
LAAS A suhsidian-vfPinnache Ili' Capital Curorwation, Palo Verde Nuclear Generating Station David M. Smith Plant Manager Nuclear Production Tel.
623-393-6116 Mail Station 7602 Fax.
623-393-6077 P.O. Box 52034 e-mail: DSMITH10@apsc.com Phoenix, AZ 85072-2034 192-01144-DMS/SAB/DGM/DFH July 8, 2004 ATTN: Document Control Desk U. S. Nuclear Regulatory Commission Washington, DC 20555-0001
Dear Sirs:
Subject:
Palo Verde Nuclear Generating Station (PVNGS) Unit I Docket No. STN 50-528 License No. NPF-41 Licensee Event Report 2004-003-00 Attached, please find Licensee Event Report (LER) 50-528/2004-003-00 that has been prepared and submitted pursuant to 10CFR50.73. The LER reports a manual reactor trip as directed by plant procedure, when a Control Element Assembly (CEA) slipped during Low Power Physics Testing.
In accordance with 1 OCFR50.4, a copy of this LER is being forwarded to the NRC Regional Office, NRC Region IV and the Resident Inspector. If you have questions regarding this submittal, please contact Daniel G. Marks, Section Leader, Regulatory Affairs, at (623) 393-6492.
Arizona Public Service Company makes no commitments in this letter. The corrective actions described in this LER are not necessary to maintain compliance with regulations.
Sincerely, DMS/SAB/DGM/DFH Attachment cc:
B. S. Mallett N. L. Salgado M. B. Fields NRC Region IV Administrator NRC Senior Resident Inspector for PVNGS NRC NRR Project Manager Th~,
APPROVED BY OMB NO. 3150-0104 EXPIRES 7-31-2004
Abstract
On May 8, 2004, at approximately 20:39 (MST), while performing Low Power Physics Testing (LPPT) in Mode 2, Palo Verde Unit 1 was manually tripped as directed by procedure 40AO-9ZZ1 1, "CEA Malfunction", when Control Element Assembly (CEA) #89 slipped from 136 inches withdrawn to 129.6 inches resulting in a deviation of 7.4 inches from the highest CEA in its' group.
No similar condition has been reported in the past three years.
NRC FORM 366 (7-2001)
(if more space is required, use additional copies of NRC Forn 366A)
1. REPORTING REQUIREMENT(S)
APS is reporting this condition pursuant to 10 CFR 50.73(a)(2)(iv)(A) as an manual reactor trip that was directed by procedure.
- 2.
DESCRIPTION OF STRUCTURE(S), SYSTEM(S) AND COMPONENT(S):
The Control Element Drive Mechanism (CEDM) (EIIS Code: AA), also known as a magnetic jack, is an electromechanical device that used induced magnetic fields to operate a mechanism for moving a Control Element Assembly (CEA).
The CEDM Control System (CEDMCS) (EIIS Code: AA), provides power and control for the CEDM's. The CEDMCS controls the application of voltage to the CEDM coils. The coils produce magnetic fields that cause motion of the Upper Lift, Upper Gripper, Lower Lift, and Lower Gripper assemblies. The gripper assemblies are also referred to as latch assemblies.
By properly sequencing the motion of the gripper and lift assemblies, the CEDM's can withdraw or insert the CEA's.
The Upper Gripper holds the CEA in place when it is stationary. If the Upper Gripper does not re-engage, the CEA will fall or if it re-engages late, the CEA will slip.
The CEA Timer Card has selector switches that are used to control the timing during a CEA motion cycle. These switches are used to determine when a specific coil is energized, how long the coil is energized and whether high or low voltage is applied. Selector settings can be adjusted so the high voltage is applied for a longer duration to compensate for sluggishness in a CEDM.
- 3.
INITIAL PLANT CONDITIONS
On May 08, 2004, at approximately 20:39 Mountain Standard Time (MST), Palo Verde Unit 1 was at normal operating temperature (NOT) and normal operating pressure (NOP) in Mode 2 at 5.0 E-2 percent power. Low Power Physic Testing (LLPT) was in progress following the 1 1th refueling outage.
There were no other major structures, systems, or components that were inoperable at the start of the event that contributed to the event. There were no failures that rendered a (If more space Is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A)
Unit 1 CEA 89 traces taken after Ul R10 revealed a slight sluggishness, but it was not recognized during its review following that outage. The re-evaluation of all other CEAs for all three units revealed no other CEAs show signs of sluggish operation.
At this time, the problem appears to be an isolated failure. Coil traces are taken periodically that will provide continued monitoring of CEDM performance. Additionally, CEDMs are exercised quarterly by surveillance testing.
No unusual characteristics of the work location (e.g., noise, heat, poor lighting) directly contributed to this event.
- 7.
CORRECTIVE ACTIONS
An independent investigation of this event is being conducted in accordance with Palo Verde's corrective action program. Based on the preliminary results from the investigation the following corrective actions have been taken or are planned to prevent recurrence:
- Discuss the sluggish gripper problem with the CEDMCS technicians to review the Coil Traces for CEDM 89 type problems.
- Update maintenance procedure to reflect the timing changes for CEA 89 in Unit 1.
- Obtain another coil trace for CEA 89 in Unit 1 to verify adequacy of the timing change.
Any additional corrective actions taken as a result of the investigation of this event will be implemented in accordance with the APS corrective action program. If information is subsequently developed that would significantly affect a reader's understanding or perception of this event, a supplement to this LER will be submitted.
8. PREVIOUS SIMILAR EVENTS
No similar condition has been reported in the past three years.
9. ADDITIONAL INFORMATION
None.