05000266/LER-2010-002, Regarding Manual Reactor Trip Due to Lowering Condenser Vacuum
| ML102660110 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 09/21/2010 |
| From: | Meyer L Point Beach |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NRC 2010-0153 LER 10-002-00 | |
| Download: ML102660110 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2662010002R00 - NRC Website | |
text
September 21,201 0 47-N u era Thl ENERGY@
POINT BEACH 7
NRC 201 0-01 53 10 CFR 50.73 U. S. Nuclear Regulatory Commission AWN: Document Control Desk Washington, DC 20555 Point Beach Nuclear Plant, Unit 1 Docket 50-266 Renewed License No. DPR-24 Licensee Event Report 2661201 0-002-00 Manual Reactor Trip Due to Lowerinn Condenser Vacuum Enclosed is Licensee Event Report (LER) 2661201 0-002-00 for Point Beach Nuclear Plant (PBNP), Unit 1. This LER documents a manual reactor scram of Unit I from approximately 19% power due to lowering condenser vacuum. Pursuant to 10 CFR 50.73(a)(2)(iv)(A), the event is reportable as "... an event or condition that resulted in manual or automatic actuation of the Reactor Protection System: including reactor scram or reactor trip."
This submittal contains no new or revised regulatory commitments.
If you have questions or require additional information, please contact Mr. James Costedio at 9201755-7427.
Very truly yours, NextEra Energy Point Beach, LLC Enclosure cc:
Administrator, Region Ill, USNRC Project Manager, Point Beach Nuclear Plant, USNRC Resident Inspector, Point Beach Nuclear Plant, USNRC PSCW NextEra Energy Point Beach, LLC, 6610 Nuclear Road, Two Rivers, WI 54241
LICENSEE EVENT REPORT (LER)
Point Beach Nuclear Plant - Unit 1 I
05000266 I
1 of 3
- 4. TITLE Manual Reactor Trip Due to Lowering Condenser Vacuum
- 5. EVENT DATE I
- 6. LER NUMBER I
- 7. REPORT DATE I
- 8. OTHER FACILITIES INVOLVED 20.2201(b) 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 1 C] 20.2201(d) 0 20.2203(a)(3)(ii) 17 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 20.2203(a)(I) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B)
- 20.2203(a)(2)(i) 50.36(c)(l)(i)(A)
C] 50.73(a)(2)(iii) 50.73(a)(2)(ix) (A) lo. POWER LEVEL Cl 20.2203(a)(2)(ii) 50.36(c)(l)(ii)(A)
IXI 50.73(a)(2)(iv)(A)
Cl 50.73(a)(2)(x) 20.2203(a)(2)(iii) 50.36(~)(2) 50.73(a)(2)(v)(A) 73.71 (a)(4) 2OS2203(a)(2)(iv)
Cl 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71(a)(5) 19%
Cl 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
OTHER 20.2203(a)(2)(vi)
- 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (Include Area Code)
R. Clark 920R55-7464 I
I I I
1 I
I I
I SUBMISSION On 7/26/2010 at 2001 CDT, operations personnel initiated a manual reactor trip of Unit 1 from approximately 19% reactor power. Unit 1 was off-line to support main generator repair. The generator breaker had just been opened and steam load was transferred to the condenser steam dumps when condenser vacuum lowered. The reactor was manually tripped in accordance with plant procedures due to a lowering of main condenser vacuum prior to an automatic trip of the reactor. All safety systems functioned as expected. All control rods fully inserted.
The lowering of condenser vacuum and subsequent manual reactor trip was caused by the improper application and adherence to human performance (HU) tool standards for self-checking. The failure to perform the self-check resulted in an incorrect status report for the turbine crossover steam dump motor operated valves, 1 MOV-1 and 1 MOV-2.
NRC FORM 366 (9-2007)
Event Description
On 7/26/2010 at 2001 CDT, Control Room personnel initiated a Unit I manual reactor trip from approximately 19% reactor power. Unit 1 was off-line to support main generator repair. The generator breaker had just been opened and steam load was transferred to the condenser steam dumps when condenser vacuum lowered. The reactor was manually tripped in accordance with plant procedures due to a lowering of main condenser vacuum prior to an automatic trip of the reactor. All systems functioned as expected. All control rods fully inserted.
In preparation for taking the generator and turbine off-line, a qualified auxiliary operator (AO) was directed to shut the Unit I turbine crossover steam dump motor operated valves and place their control switches to stop. The A 0 incorrectly read the local position indication for the valves as shut, when in fact the valves were open. The turbine crossover steam dump valves remained open when the control switch was subsequently placed in stop.
The errant local position indication reading resulted in the A 0 reporting that the turbine crossover steam dump valves were closed to the Control Room. The Control Room proceeded with the main generator shutdown in accordance with plant procedures. After the turbine and generator were taken offline, the lowering of crossover steam pressure allowed air to flow through the open crossover steam dump isolation valves into the Unit I main condenser. The lowering of condenser vacuum would not sustain plant operation. As a result, Unit I reactor was manually tripped.
An event notification was made on July 26, 201 0, in accordance with the requirements of 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A).
This 60-day licensee event report is being submitted in accordance with the requirements of I 0 CFR 50.73(a)(2)(iv)(A).
Event Analysis
On July 26, 2010, at approximately 0900 CDT, Operations began preparations to downpower Unit I to take the generator and turbine offline to support main generator repair. At 1242 CDT on July 26, Operations commenced the load ramp of Unit I at 15% per hour in accordance with plant procedures.
During the load ramp, the Senior Reactor Operator (SRO) for Unit 1 directed an Auxiliary Operator (AO) to shut the Unit 1 turbine crossover steam dump motor operated valves, I MOV-I and I MOV-2 and place their control switches to stop. The proper use of self-checking was not discussed in the brief between the SRO and AO. The A 0 left the control room and went to the crossover steam dump control panel. The A 0 looked at the control panel and incorrectly perceived that both I MOV-1 and I MOV-2 were already shut.
However, the RED (OPEN) lights were lit for each valve, and the corresponding position meters indicated open. Believing that both turbine crossover steam dump motor operated valves were closed, the A 0 took the control switch to STOP. Following completion of this activity, the A 0 called the Control Room to report the status of the valves as SHUT. This status was incorrect as the valves were still OPEN.
oint Beach Nuclear Plant - Unit 1 The Control Operator received and acknowledged the call from the A 0 stating the step was complete. The Control Room proceeded with the main generator shutdown in accordance with plant procedures with an incorrect awareness to the status of I MOV-1 and I MOV-2.
At 1958 CDT, the Unit I generator main breaker was opened in accordance with the procedure. After the turbine generator was taken offline, the lowering of crossover steam pressure allowed air to flow through the open crossover steam dump isolation valves into the Unit I main condenser. This created the lowering vacuum condition for the Unit 1 main condenser. At 2001 CDT, Unit 1 reactor was manually tripped due to lowering vacuum in the Unit I main condenser.
There were no equipment failures associated with this event. Therefore, the event does not represent a safety system functional failure.
Safety Significance
During the event and subsequent recovery actions, there was no loss of a safety-related system, structure, or component. The plant response following the manual reactor trip was as expected. Although the event was a manual actuation of the reactor protection system, plant equipment performance allowed a stable configuration to be maintained. Thus, the safety significance of the event was low. There was no impact on the health and safety of the public as a result of this event.
Cause
The lowering of condenser vacuum and subsequent manual reactor trip was caused by the improper application and adherence to human performance (HU) tool standards for self-checking. The failure to perform the self-check resulted in an incorrect status report for the turbine crossover steam dump motor operated valves, I MOV-I and I MOV-2.
Corrective Action
The following corrective action was taken:
Operations has implemented job performance measures (JPM) to instruct and evaluate the ability of an operator to perform A self-check (STAR) correctly.
Additional corrective action to be taken:
Operations to change the auxiliary operator continual training program, to permanently institute HU training JPMs for auxiliary operators and licensed operators.
Previous Occurrences
There have been no similar LERs submitted within the last three years.
Failed Components Identified: None