05000251/LER-2004-004, Regarding Manual Reactor Trip Due to Lowering Condenser Vacuum
| ML050610503 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 02/23/2005 |
| From: | Jones T Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2005-032 LER 04-004-00 | |
| Download: ML050610503 (5) | |
| 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)(iv)(B), System Actuation 10 CFR 50.73(a)(2)(iv)(B)(2) 10 CFR 50.73(a)(2)(iv)(B)(6) |
| 2512004004R00 - NRC Website | |
text
FPL FEB 2 3 2005 10 CFR § 50.73 L-2005-032 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re:
Turkey Point Unit 4 Docket No. 50-251 Reportable Event: 2004-004-00 Date of Event: December 25, 2004 Manual Reactor Trip Due to Lowering Condenser Vacuum The attached Licensee Event Report 251/2004-004-00 is being submitted pursuant to the requirements of 10 CFR 50.73(a)(2)(iv)(A) to provide notification of the subject event.
If there are any questions, please call Mr. Walter Parker at (305) 246-6632.
Very truly yours, 4/Terry 0. Jones Vice President Turkey Point Nuclear Plant Attachment cc:
Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant
)
- - 1 an FPL Group company
NRrFORM t66 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06130/2007 (6-2=4)
Estimated burden per response to comply with this mandatory collection request:
50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Reported lessons learned are Incorporated Into the licensing process and fed back to industry. Send comments regarding burden estimate to the Records J
,,and FOlAtPrivacy Service Branch C1-5 F52), U.S. Nuclear Regulatory Commission, LICENSEE EVENT REPORT (LER)
Washington, DC 20555-0001, or by internet e-mail to Infocollectsenrc.gov, and to the Desk Officer. Office of Information and RegulatoryAffairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an Information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the Information collection.
- 3. PAGE Turkey Point Unit 4 05000251 1 OF 4
- 4. TITLE Manual Reactor Trip Due to Lowering Condenser Vacuum
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEUNIA E
ACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER REV MONTH DAY YEAR I
FACILITY NAME DOCKET NUMBER 12 25 2004 2004 - 004 - 00 02 24 2005
- 9. OPERATING MODE 11.THIS REPORTIS SUBMITED PURSUANT i OTHE REQUIREMENTS OF 10CFR§: (Checkallthatapply) 0 20.2201(b) 0 20.2203(a)(3)(i)
D 50.73(a)(2)(i)(C)
E 50.73(a)(2)(vii) 0 20.2201(d)
D 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) o 20.2203(a)(1) 0 20.2203(a)(4) a 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B) 0 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iii) 0 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 0
20.2203(a)(2)(ii) 0 50.36(c)(1)(ii(A) 0 50.73(a)(2)(iv)(A) 0 50.73(a)(2)(x)
O 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4)
O 20.2203(a)(2)(iv) 0I 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B) 0 73.71(a)(5) 100 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C) 0 OTHER o 20.2203(a)(2)(vi) 0l 50.73(a)(2)(i)@)
0I 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)
Ron Everett - Licensing Engineer 305-246-6190CAUSE SYSTEM COMPONENT MANU-R REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE B
SG COND F175 N
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION 0D YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 0 NO DATE 08 15 2005 ABSTRACT (Limit to 1400 spaces, I.e., approximately 15 single-spaced typewritten lines)
On December 25, 2004, at 07:36 EST with Unit 4 operating in Mode 1 at 100 percent power, Turkey Point Unit 4 experienced a declining vacuum in the main condenser. When condenser vacuum reached less than 22 inches Hg, reactor trip criteria was met and the plant was manually shut down. Decay heat was removed via the Atmospheric Steam Dumps. The Auxiliary Feedwater System automatically started as expected. All rods inserted correctly and all systems functioned as designed. The apparent cause of the lowering condenser vacuum was failure of a turbine slop drain line inside the condenser. Corrective action was taken to temporarily plug the inlet and outlet ends of the leaking slop drain until the condenser interior can be accessed and permanent repairs completed. The health and safety of the public were not affected by this event.
NR
_OR
.6(-04 RNE NRCCE AE NFIC FORM 366 (62004)
PRINTED ON RECYfCLED PAPER
N. % FORM 366A U.S. NUCLEAR REGULATORY COMMISSION (7>6001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
NUMBER 2 LER NUMBER (6)
PAGE (3)
Y., SEQUENTIAL REVISION Turkey Point Unit 4-05000251 NUMBER NER Page 2 of 4 200-004
- - 00 TEXT (If more space Is required, use additional copies of NRC Form 366A) (17)
DESCRIPTION OF THE EVENT On 12/25/04 Unit 4 experienced a sudden loss of condenser [EIIS: SG] vacuum. Annunciator E-5/3, Condenser Lo Vacuum alarmed [EIIS: SG, P1]. Operators noted one pressure indicator (PI) at 27 inches Hg and one PI at 24.5 inches Hg and lowering rapidly. Operations staff noted Gross Generation had lowered 40 MWe and referred to station Alarm Response Procedures and Off-Normal procedures for actions to restore condenser vacuum. The Steam Jet Air Ejector Hogging jet [EIIS:SB, P] was placed in service to restore vacuum and the operators commenced reducing turbine load. However, vacuum could not be recovered and the reactor was manually tripped when vacuum decreased to about 22 inches Hg.
Actions to resolve the cause of the condenser vacuum loss were completed, and Unit 4 was restarted on 12/26/04. In accordance with I0CFR 50.72(b)(2)(iv)(B), a four-hour Emergency Notification System report was made to the NRC Operations Center on December 25, 2004, at 08:50 (Event Number 41292) for the manual reactor trip.
ANALYSIS OF THE EVENT
At the time of the event, the plant was in Mode 1 at 100% power with automatic Reactor Coolant System [EIIS: AB] (RCS) pressure control operational. A 100% loss of load resulted when the turbine was tripped by the manual reactor trip due to lowering condenser vacuum. The plant response for this trip was comparable to that for a loss of electrical load event due to a turbine trip, analyzed in UFSAR section 14.1.
UFSAR minimum and maximum values were not exceeded during this transient. The Auxiliary Feedwater System [EIIS: BA] auto-initiated as required, due to the expected decrease in steam generator levels below 10% narrow range on a reactor trip from 100% power. The 4C Charging pump [EIIS: CB, PI was started during the event to maintain RCS inventory. The RCS pressure remained below the setpoint for pressurizer PORV or Code safety valve actuation. No unexplained aspects of this transient, when compared to the UFSAR, were noted.
CAUSE OF THE EVENT
The cause of the Unit 4 manual reactor trip was operator response to lowering condenser vacuum. Based on inspection and air being sucked into the condenser slop drain common header, the cause was concluded to be a leak in one of the slop drains. The slop drain system drains oil and water leaking from the bearing and gland seals on both ends of the LP1 and LP2 (low pressure) turbines. The four 1/4-inch lines are routed through the condenser and join together at a common oil waste drain. The condenser air in-leakage was stopped by temporarily plugging the leaking slop drain at the inlet and outlet. The conditions causing the event are applicable to the remaining seven slop drain pipes for Units 3 and 4. Therefore, these drains were likewise plugged. A failure analysis will be performed once the condenser internals can be accessed (during the 2005 Unit 4 cycle 22 refueling outage).IU.S. NUCLEAR REGULATORY COMMISSION I(7?;2OO1)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
NUMBER (2)
LER NUMBER (6)
PAGE (3) l YEAR ISEQUENTIAL I REVISION Turkey Point Unit 4 05000251 NUMBER NUMBER Page 3 of 4 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
REPORTABILITY
A review of the reporting requirements of 10 CFR 50.72 and 10 CFR 50.73 and NRC guidance provided in NUREG-1022, Revision 2, Event Reporting Guidelines 10 CFR 50.72 and 10 CFR 50.73, was performed for the subject condition. As a result of this review, the condition is reportable as described below.
10CFR50.73(a)(2)(iv)(A) states that the licensee shall report any event or condition that resulted in a manual or automatic actuation of any of the systems listed in 10CFR50.73(a)(2)(iv)(B). Systems to which the requirements of 10CFR50.73(a)(2)(iv)(A) apply include the Reactor Protection System (RPS) actuation resulting in a reactor scram or manual trip (10 CFR 50.73(a)(iv)(B)(1). Unit 4 was manually tripped in response to the lowering condenser vacuum. The event is also reportable in accordance with 10 CFR 50.73 (a)(2)(iv)(A), due to MSIV closure (10 CFR 50.73(a)(2)(iv)(B)(2)), and AFW system actuation (10 CFR 50.73(a)(2)(iv)(B)(6)).
ANALYSIS OF SAFETY SIGNIFICANCE This event had no significant effect on the health and safety of the public. A manual reactor trip was initiated in response to the lowering condenser vacuum. All safety systems operated as designed; and no unexplained aspects of this transient, when compared to the UFSAR, were noted. Therefore, there were no actual safety consequences for the event. The condenser continued to function as a heat sink and condenser steam dumps remained operable throughout this event. Post-trip reviews established that plant parameters were within UFSAR analyzed minimum and maximum values for a loss of load event. No radiological release occurred. Therefore, the health and safety of the public were not affected by this event.
CORRECTIVE ACTIONS
Short Term - As an interim repair, the inlet and outlet ends of the leaking slop drain were plugged. The other slop drains on both units were plugged.
Long Term - An inspection of the piping and failure analysis will be completed during the 2005 Unit 4 Cycle 22 refueling outage.
ADDITIONAL INFORMATION
EIIS Codes are shown in the format [EHS SYSTEM: IEEE system identifier, component function identifier, second component function identifier (if appropriate)].
FAILED COMPONENTS IDENTIFIED:
SLOP DRAIN INTEGRITY FAILUREU.S. NUCLEAR REGULATORY COMMISSION (7I2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET LER NUMBER (6)
PAGE (3)
N U M B ER (2)
YEAR SEUNTIAL REVISION Turkey Point Unit 4 05000251 YAl ER NUMER Page 4 of 4 2004 -
004 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
SIMILAR EVENTS
A review of previous Licensee Event Reports identified LER 2001-003-00, Manual Reactor Trip Due to Low Condenser Vacuum. However, the root cause was different: inadequately designed sensing lines for the control room condenser vacuum instrumentation and the turbine low vacuum alarm.