05000302/LER-2008-003, Manual Reactor Trip Due to Main Feedwater System Oscillations Caused by an Inconsistent Procedure
| ML083010236 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 10/21/2008 |
| From: | Holt J Florida Power Corp, Progress Energy Co, Progress Energy Florida |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 3F1008-04 LER 08-003-00 | |
| Download: ML083010236 (7) | |
| 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 |
| 3022008003R00 - NRC Website | |
text
0Progress Energy Crystal River Nuclear Plant Docket No. 50-302 Operating License No. DPR-72 Ref: 10 CFR 50.73 October 21, 2008 3F1008-04 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
Subject:
CRYSTAL RIVER UNIT 3 - LICENSEE EVENT REPORT 50-302/2008-003-00
Dear Sir:
Florida Power Corporation, currently doing business as Progress Energy Florida, Inc., hereby submits Licensee Event Report (LER) 50-302/2008-003-00.
The LER discusses a manual reactor trip due to Main Feedwater System oscillations caused by an inconsistent procedure.
This report is being submitted pursuant to 10 CFR 50.73(a)(2)(iv)(A).
No new regulatory commitments are made in this letter.
If you have any questions regarding this submittal, please contact Mr. Dan Westcott, Supervisor, Licensing and Regulatory Programs, at (352) 563-4796.
Sinc ely, J~'mes W. Holt Plant General Manager Crystal River Nuclear Plant JWH/dwh Enclosure xc:
Regional Administrator, Region II Senior Resident Inspector NRR Project Manager Progress Energy Florida, Inc.
Crystal River Nuclear Plant 15760 W. Powerline Street Crystal River, FL 34428
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the 9
information collection.
- 13. PAGE CRYSTAL RIVER UNIT 3 05000302 1 of 6
- 4. TITLE Manual Reactor Trip Due To Main Feedwater System Oscillations Caused By An Inconsistent Procedure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR 05000 NUMBER NO.
500 FACILITY NAME DOCKET NUMBER 08 24 2008 2008 - 003 -
00 10 21 2008 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii)
El 20.2201(d) 0l 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i) 0l 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
-] 50.36(c)(2)
[1 50.73(a)(2)(v)(A)
El 73.71(a)(4)
[I 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5)
- - 60%
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
El 50,73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Dennis W. Herrin, Lead Engineer (Licensing and Regulatory Programs) j.352-563-4633SYSTEM MANU-REPORTABLE C
MANU-REPORTABLE
CAUSE
COMPONENT FACTURER TO EPIX
CAUSE
SYSTEM cOMPONEN FACTURER TO EPIX X
SD CPLG E120 Y
- 14. SUPPLEMENTAL REPORT EXPECTED
- - 7
- 15. EXPECTED MONTH DAY YEAR_
0 YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 0 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
At 15:53 on August 24, 2008, Progress Energy Florida, Inc. (PEF), Crystal River Unit 3 (CR-3) was operating in MODE 1 (POWER OPERATION) at approximately 60 percent RATED THERMAL POWER, when the reactor was manually tripped. At 15:37, the Condensate Pump CDP-1A magnetic coupling became uncoupled. Delays in rapid power reduction led to a low Deaerator (FWHE-1) level and eventual cavitation of the Main Feedwater (FW) System booster pumps and Main FW pumps. The cavitation caused a loss of FW flow control to the Once-Through Steam Generators. The decision was made to manually trip the reactor. The root cause for this event was inconsistent and misunderstood requirements for the FW booster pumps. An operating procedure stated that operation of the FW booster pumps with < 6 feet level in the Deaerator should be avoided, but also stated that the FW booster pump automatic trip setpoint was < 2 feet and 10 inches. This inconsistent guidance led to the loss of FW flow control. Required equipment operated as designed during the manual reactor trip. Loss of FW is an analyzed event bounded by the CR-3 Final Safety Analysis Report accident analysis. This condition does not represent a reduction in the public health and safety. The operating procedure has been revised to prohibit operation with < 6 feet level in FWHE-1. A previous similar occurrence has not been reported to the NRC.
NRC FORM 366 (9-2007)
PRINTED ON RECYCLED PPERU.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL I REVISION YEAR NUMBER NUMBER CRYSTAL RIVER UNIT 3 105000-302 2008 003 00 2
OF 6
EVENT DISCRIPTION At 15:53 on August 24, 2008, Progress Energy Florida, Inc. (PEF), Crystal River Unit 3 (CR-3) was operating in MODE 1 (POWER OPERATION) at approximately 60 percent RATED THERMAL POWER, when the reactor was manually tripped due to Main Feedwater (FW) System [SJ] flow oscillations.
At 15:37 on August 24, 2008, the Condensate Pump CDP-1A [SD, P1 magnetic coupling (Electric Machinery, Model MSD4404V) [SD, CPLG] became uncoupled and resulted in numerous alarms in the Main Control Room. The alarms resulted in distractions and the operating crew was not aware of the loss of CDP-1A for several minutes. Significant lowering of Condensate System [SD] flow and a lowering Deaerator (FWHE-1) [SD, TK] level was not immediately diagnosed. In response to a lowering FWHE-1 level and recognition that CDP-1A amperage was well below normal, efforts to re-couple CDP-1A were directed, concurrent with entry into Abnormal Operating Procedure AP-510, "Rapid Power Reduction." Reactor power was reduced from 100 percent RATED THERMAL POWER and stabilized at approximately 62 percent RATED THERMAL POWER with the FWHE-1 level recovering.
At this time, FW block valve FWV-29 [SJ, ISV] to the "B" Once-Through Steam Generator (OTSG)
[SB, SG] began to close, lowering the "B" OTSG level. FW block valve FWV-30 to the "A" OTSG remained full open. Oscillations were observed to be occurring on Main FW pump FWP-2B [SJ, P]
flow between 0-100 percent demand while FWP-2A flow was pegged high. In response to the high FW System [SJ] flow condition on the "A" OTSG, FWV-30 was placed in manual and closed. FW System flow oscillations were still occurring, along with resultant reactor power oscillations, so the decision was made to manually trip the reactor. A turbine trip occurred simultaneously. Following completion of post-trip actions, FWP-2B oscillations continued. FW cross-connect valve FWV-28 was opened and FWP-2B was manually tripped.
No structures, systems or components were inoperable at the start of the event that contributed to the event. No other pertinent maintenance or surveillance activities were in progress. Plant protection and non-protection systems operated normally during the manual reactor trip, with the exception of the following:
FWP-2A locked in at 100% demand during the power reduction causing control issues and overfeed/overfill of the "A" OTSG. The FWP-2A Woodward 505 digital governor controller [SJ, 65] interpreted a transient condition as a control failure due to a circuit design feature and locked in at the last good signal.
At 18:03 on August 24, 2008, a 4-hour notification to the NRC Operations Center (Event Number 44438) was made in accordance with 10 CFR 50.72(b)(2)(iv)(B) for manual actuation of the Reactor Protection System (RPS) [JC]. An update was provided at 19:21 on August 24, 2008.
This condition is being reported as a 60-day Licensee Event Report under 10 CFR 50.73(a)(2)(iv)(A) for manual actuation of the RPS.PRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPERU.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL I REVISION YEAR NUMBER NUMBER CRYSTAL RIVER UNIT 3 105000-302 2008 003 00 3
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SAFETY CONSEQUENCES
Manual actuation of the RPS was initiated to shut down the reactor and maintain adequate OTSG levels. Upon initiation of the manual reactor trip, the RPS responded as expected, control rods fully inserted and safety systems functioned as required. No challenges to the RPS were identified. No Emergency Feedwater Initiation and Control System [BA] actuation occurred or was expected. Both OTSGs were fed by the FW System throughout this event.
This event did not result in the release of radioactive material. No design safety limits were exceeded and no fission product barriers or components were damaged as a result. The loss of Feedwater is an event analyzed and bounded by the Final Safety Analysis Report accident analysis.
Based on the above discussion, PEF concludes that manual actuation of the RPS did not represent a reduction in the public health and safety.
This event is not reportable under 10 CFR 50.73(a)(2)(v) and does not represent a condition that would have prevented the fulfillment of a safety function. Therefore, this event does not meet the Nuclear Energy Institute (NEI) definition of a Safety System Functional Failure (Reference: NEI 99-02, Revision 5).
CAUSE
The root cause for this event was inconsistent and misunderstood requirements for the FW booster pumps [SJ, P1. The Shift Technical Advisor made a recommendation to the Superintendent Shift Operations (SSO) to consider entry into AP-510 based on FWHE-1 level at approximately 8 feet in level. The SSO considered the FWHE-1 level to be a concern but thought there was margin until FW booster pump cavitation. The perceived margin came from the Limits and Precautions in Operating Procedure OP-605, "Feedwater System," Section 3.2.11, which stated that operation of FW booster pumps < 6 feet FWHE-1 level "should be avoided." OP-605 specified a FW booster pump automatic trip setpoint of -- 2 feet and 10 inches level in FWHE-1. The operating crew believed that FW pump cavitation would not occur until FWHE-1 level approached the trip setpoint.
This inconsistent guidance, along with slow diagnosis of the CDP-1A loss, resulted in not entering AP-510 in a timely manner. Cavitation of both FW booster pumps and Main FW pumps occurred at approximately 4.75 feet FWHE-1 level and caused the loss of FW flow control to the OTSGs.
Corrective Actions
- 1.
The Limit and Precaution of OP-605, Section 3.2.11, has been revised to prohibit operating the FW booster pumps < 6 feet indicated level in FWHE-1.
- 2.
The CDP-1A motor and clutch assembly was replaced with a refurbished spare under Work Order 1406343. (Nuclear Condition Report (NCR) 294686)
NRC FORM 369A (9-2007)
PRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPERU.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL I REVISION YER NUMBER NUMBER CRYSTAL RIVER UNIT 3 05000-302 2008 003 00 4
OF 6
- 3.
The FWP-2A Woodward 505 digital governor controller was modified by Engineering Change 71126 (Work Order 1407302) to limit the signal range received from the Integrated Control System, bypassing the lockout feature. (NCR 293609)
- 4.
Additional corrective actions are identified in NCR 293080.
PREVIOUS SIMILAR EVENTS
Although FW pump oscillations have occurred at CR-3, a review of Licensee Event Reports submitted to the NRC in the past 10 years did not reveal any automatic or manual actuations of the RPS due to loss of FW System control caused by a low FWHE-1 level.
ATTACHMENTS - Abbreviations, Definitions, and Acronyms - List of CommitmentsPRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPERU.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL I REVISION YER I
NUMBER NUMBER CRYSTAL RIVER UNIT 3 105000-302 2008 003 00 5
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Abbreviations, Definitions, and Acronyms AP Abnormal Operating Procedure CDP Condensate Pump CFR Code of Federal Regulations CR-3 Crystal River Unit 3 FWHE-1 Deaerator FW Main Feedwater System FWP Main Feedwater Pump FWV Main Feedwater Valve NCR Nuclear Condition Report NEI Nuclear Energy Institute NRC Nuclear Regulatory Commission OP Operating Procedure OTSG Once-Through Steam Generator PEF Progress Energy Florida, Inc.
RPS Reactor Protection System SSO Superintendent Shift Operations NOTES:
Improved Technical Specification Defined terms appear capitalized in LER text
{e.g., MODE 1}.
Defined terms/acronyms/abbreviations appear in parenthesis when first used {e.g.,
Reactor Building (RB)}.
EIIS Codes appear in square brackets {e.g., reactor building penetration [NH, PEN]}PRINTED ON RECYCLED PAPERU.S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL REVISION YER NUMBER NUMBER CRYSTAL RIVER UNIT 3 05000-302 2008 003 00 6
OF 6
LIST OF COMMITMENTS The following table identifies those actions committed by PEF in this document. Any other actions discussed in the submittal represent intended or planned actions by PEF. They are described to the NRC for the NRC's information and are not regulatory commitments. Please notify the Supervisor, Licensing and Regulatory Programs of any questions regarding this document or any associated regulatory commitments.
RESPONSE
C(
SECTION No regulatory commi in this submittal.
NRC FORM 368A (9-2007)
PRINTED ON RECYCLED PAPERPRINTED ON RECYCLED PAPER