05000483/LER-2002-013, RPS Actuation in Mode 4 While Performing Tadot Testing
| ML030230725 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 01/17/2003 |
| From: | Witt W AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-04797 LER 02-013-00 | |
| Download: ML030230725 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 4832002013R00 - NRC Website | |
text
Union Electric PO Box 620 Calfaway Plant Fulton, MIO 65251 January 17, 2003 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P 1-137 Washington, DC 20555-0001 ULNRC-04797 wAmeren UE Ladies and Gentlemen:
DOCKET NUMBER 50-483 Callaway PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2002-013-00 RPS actuation in Mode 4 while performing TADOT testinl The enclosed licensee event report is submitted in accordance with 10CFR50.73(a)(2)(iv)(A) to report a Reactor Protection System (RPS) actuation in Mode 4 while performing a Trip Actuating Device Operational Test (TADOT)
Very truly yours, a/aA~M 4-Warren A. Witt Manager, Callaway Plant WAW/ewh Enclosure a subsidiary of Ameren Corporation
ULNRC-04797 January 17, 2003 Page 2 cc:
Mr. Ellis W. Merschoff Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Jack N. Donohew (2 copies)
Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop 7E1 Washington, DC 20555-2738 Manager, Electric Department Missouri Public Service Commission PO Box 360 Jefferson City, MO 65102 Records Center Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339
Abstract
At 2156, 11/21/02, with Callaway Plant in Mode 4 at zero percent power, an unplanned actuation of "B" Reactor (Rx) Trip Breaker occurred while performing plant procedure OSP-SB-0002B, Reactor Trip Breaker 'B' TADOT (Trip Actuating Device Operational Test) - Shutdown. At step 6.4.9.2, the Solid State Protection System (SSPS) logic testing switch "A" was inadvertently mispositioned, which activated permissive P-10. This in turn activated permissive P-7, which enabled the Lowv Pressurizer Pressure Reactor Trip set at 1885 psig. With the Reactor Coolant System (RCS) at approximately 970 psig, a low pressure was sensed, processed by SSPS, and a trip signal sent which opened the "B" Rx Trip Breaker. Since the plant was already shutdown, no adverse consequences resulted. An Event Review Team (ERT) was convened to review the event. It was determined that the event was due to human error caused by over-rotating the SSPS logic switch. Proposed corrective actions include a procedure enhancement on test switch alignment and manipulations NRC FORM 366 (7-2001)
(If more space is required, use additional copies of SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES At 2156, 11/21/02, with Callaway Plant in Mode 4 at zero percent power, an unplanned actuation of "B" Reactor (Rx) Trip Breaker occurred while performing plant procedure OSP-SB-0002B, Reactor Trip Breaker 'B' TADOT-Shutdown.
Prior to performing the procedure, a pre-job brief was conducted due to the critical nature of the test to be performed. During the pre-job brief Operating Experience (OE) was covered discussing the potential results of mispositioning these SSPS logic testing switches. These switches are multiposition selector switches that can be rotated 360 degrees either counterclockwise or clockwise.
At step 6.4.9.2, the Solid State Protection System (SSPS) logic testing switch "A" was inadvertently mispositioned by over-rotating the switch one position counterclockwise, which activated normally blocked permissive P-10. This in turn activated permissive P-7, which enabled the Low Pressurizer Pressure Reactor Trip set at 1885 psig. With the Reactor Coolant System (RCS) at approximately 970 psig, a low pressure was sensed, processed by SSPS, and a trip signal sent which opened the "B" Rx Trip Breaker. Additionally, P-10 also blocked source range high voltage and thus Source Range (SR) channel N-32 was de-energized. Since both Rod Drive Motor Generators were secured and control rod vithdrawval was not possible, the loss of SR N32 did not violate Techlical Specification 3.3.1, Table 3.3.1-1 Function 5.
Upon mispositioning the switch, the licensed operator immediately recognized the error and stopped all further procedure performance. The Control Room staff was immediately aware of the error due to receiving unexpected alarm annunciators. A meeting was held with Operations and Instrument and Control personnel to discuss what had occurred and determine how to restore from the event. Once a plan of action was established, restoration was performed as expected and the procedure wvas then successfully completed Since the plant was already shutdown, no adverse consequences resulted. An Event Review Team (ERT) was convened to review the event. It was determined that the event was due to human error caused by over-rotating the SSPS logic switch. Proposed corrective actions include a procedure enhancement on test switch alignment and manipulations.
E. METHOD OF DISCOVERY OF EACH COMPONENT, SYSTEM FAILURE, OR PROCEDURAL ERROR Upon mispositioning the SSPS Logic Switch, the Licensed Operator recognized the error and immediately stopped The Control Room was immediately aware of the problem due to unexpected alarm annunciators being received.
(If more space Is required, use additional copies of NRC Form 366A) (17)
II.
EVENT DRIVEN INFORMATION A. SAFETY SYSTEMS THAT RESPONDED The Reactor Protection System (RPS) sensed an actual plant parameter that satisfied the criteria for generating an actuation signal and responded appropriately.
B. DURATION OF SAFETY SYSTEM INOPERABILITY
Not Applicable for this event.
C. SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT.
At the time of this event, the plant was shutdown in Mode 4 with all rods fully inserted and both rod drive motor generator sets de-energized. There was no safety consequence due to this event.
III.
CAUSE OF THE EVENT
The cause of the event was human error when positioning the SSPS Logic Switch.
IV.
CORRECTIVE ACTIONS
Proposed corrective actions include a procedure enhancement on test switch alignment and manipulations V.
PREVIOUS SIMILAR EVENTS
There has been one similar LER, 2001-001-00, event involving TADOT testing This occurred on 1/21/01 when a non-licensed individual failed to perform a step within a plant procedure, which resulted in the actuation of the "A" Rx Trip Breaker.
A review of the Callaway Action Request (CAR) system for the previous three years only identified one CAR, 200100116, which documents the event described in the above mentioned LER VI.
ADDITIONAL INFORMATION
The system and component codes listed below are from the IEEE Standard 805-1984 and IEEE Standard 803A-1984 respectively.
System:
NOT APPLICABLE - THIS EVENT WAS NOT CAUSED BY COMPONENT OR SYSTEM FAILURE Component: