05000317/LER-2011-003, Regarding 1A Emergency Diesel Generator Inoperability Due to Water Intrusion
| ML11354A244 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 12/16/2011 |
| From: | Costanzo C Calvert Cliffs, Constellation Energy Nuclear Group, EDF Development |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 11-003-00 | |
| Download: ML11354A244 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(iv)(A), System Actuation 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 |
| 3172011003R00 - NRC Website | |
text
Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 CENG.
a joint venture of wEnergy 1
D CALVERT CLIFFS NUCLEAR POWER PLANT December 16, 2011 U.S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
SUBJECT:
Document Control Desk Calvert Cliffs Nuclear Power Plant Unit Nos. 1 and 2; Docket Nos. 50-317 and 50-318; License Nos. DPR 53 and DPR 69 Licensee Event Report 2011-003, Revision 00 IA Emergency Diesel Generator Inoperability Due to Water Intrusion The attached report is being sent to you as required by 10 CFR 50.73.
Should you have questions regarding this report, please contact Mr. Douglas E. Lauver at (410) 495-5219.
Very truly yours, Plant General Manager CRC/CAN/bjd
Attachment:
As stated cc:
D. V. Pickett, NRC W. M. Dean, NRC Resident Inspector, NRC S. Gray, DNR
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-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 and FOIA/Privacy Section (T-5 F53), U.S. Nuclear LICENSEE EVENT REPORT (LER)
Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to infocollects.resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of (See reverse for required number of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control digits/characters for each block) number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Calvert Cliffs Nuclear Power Plant, Unit 1 05000317 1 OF 6
- 4. TITLE 1A Emeraencv Diesel Generator InoDerabilitv Due to Water Intrusion
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE 1
- 8. OTHER FACILITIES INVOLVED S
NONTH DAY YEAR REV FACILITY NAME DOCKET NUMBER E
YEAR SNUMBER NO.
MONTH DAY YEAR CCNPP, Unit 2 05000 318 FACILITY NAME DOCKET NUMBER 10 21 2011 2011
- - 003 -
00 12 16 2011 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
[1 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 10 20.2201(d)
[I 20.2203(a)(3)(ii)
[I 50.73(a)(2)(ii)(A)
[I 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
Z 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
_E 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
E3 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL EJ 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
[I 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
[E 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71(a)(5) 096 El 20.2203(a)(2)(v)
[I 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
[E OTHER El 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
Z 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)
C. A. Neyman, Senior Engineering Analyst 1410-495-3507CAUSE SYTM CMOET MANU-REPORTABLE I AS YTMICMOET MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX B
NB SEAL Y
X EK SIS N
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED M ONTH DAY YEAR SUBMISSION El YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
[
NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On October 21, 2011, Calvert Cliffs Nuclear Power Plant discovered that a reportable condition existed. On August 28, 2011, numerous alarms were received for the 1A Emergency Diesel Generator (EDG) (train A, one of two safety-related EDGs dedicated to Unit 1). Water was intruding down the diesel generator intake piping, resulting in a short circuit on the 1A2 engine speed switch circuit. The 1A EDG was declared inoperable and appropriate Technical Specifications were implemented. The 1A2 engine speed switch assembly was cleaned, dried, and inspected. The 1A EDG was returned to operable status. Corrective actions include repair of the affected piping penetrations.
A root cause analysis determined the most probable root cause to be the penetration around the 1A2 engine combustion air intake pipe on the 80 foot level of the 1A EDG Building was unable to perform its design function of being leak tight. This may have occurred due to improper installation, manufacturing defect, degradation, or original design considerations. This condition may have existed since construction of the 1A EDG Building in 1996. There have been no licensee event reports for similar events at Calvert Cliffs.
NRC FORM 366 (10-2013)U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REV YEAR NUMBER NO.
Calvert Cliffs Nuclear Power Plant, Unit 1 05000 317 2011
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- 1.
DESCRIPTION OF EVENT
A.
PRE-EVENT PLANT CONDITIONS:
Unit 1 was operating at 95.5 percent power and Unit 2 was operating at 99.5 percent power on October 21, 2011.
B.
EVENT:
At 0000 on August 28, 2011, numerous alarms were received for the 1A Emergency Diesel Generator (EDG) (train A, one of two safety-related EDGs dedicated to Unit 1). Water was intruding down the diesel generator intake piping resulting in a short circuit on the 1A2 engine speed switch circuit. Based on these indications the 1A EDG was declared inoperable and appropriate Technical Specifications were implemented. During the event, there was no demand for the 1A EDG.
On October 21, 2011, it was determined that the condition that caused the 1A EDG inoperability may have existed since construction of the 1A EDG Building in 1996.
C.
INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO THE EVENT:
There were no additional inoperable structures, components, or systems that contributed to the event.
D.
DATES AND APPROXIMATE TIMES OF MAJOR OCCURRENCES
On August 27, 2011, operators made preparations for the impending Hurricane Irene.
At 1800, the Shift Manager briefed operators regarding the need to look for water intrusion.
Frequency for operator rounds was increased to every two hours.
At 2248, Unit 1 reactor tripped. At this time, the Shift Manager made the decision for no one to go outside for personnel safety reasons and suspended the rounds to the 1A Diesel Generator Building. This prevented the next rounds scheduled for 2340.
On August 28, 2011, at 0000, the 1A EDG was declared inoperable due to receiving several alarms. Both of Unit 2 EDGs and the 1 B EDG was verified operable and the OC Diesel Generator was verified available.
At 0040, operators observed water leaking from the 1A2 exhaust stack onto some of the engine relays.
At 0400, craft discovered that the 1A EDG control circuitry was attempting to establish a generator field. The associated circuits were de-energized to prevent damage to the circuit.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE I
SEQUENTIAL REV YEAR NUMBER NO.
Calvert Cliffs Nuclear Power Plant, Unit 1 05000 317 2011
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of 06 On August 29, 2011 at 1030, the 1A EDG was declared operable.
On October 21, 2011, it was determined that the condition that caused the 1A EDG inoperability may have existed since construction of the 1A EDG Building in 1996.
E.
OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED
The Technical Specifications require one EDG from the other unit to be capable of supplying power to the Control Room Emergency Ventilation System and the Control Room Emergency Temperature System. The 1A EDG provides this Technical Specification function for Unit 2.
No other systems or secondary functions were affected.
F.
METHOD OF DISCOVERY
The failure of 1A EDG on August 28, 2011, was self-revealing. On October 21, 2011, it was determined that the condition that caused the 1A EDG inoperability may have existed since construction of the 1A EDG Building in 1996.
G.
MAJOR OPERATOR ACTION:
Operators entered Technical Specification 3.8.1.B and 3.8.1.E, "AC Sources - Operating" and performed verification of power distribution system operability of off-site power and equipment in train B in accordance with station procedures. When it was discovered that the 1A EDG was continuing to attempt to establish a generator field, craft de-energized the associated circuits to prevent damage to the circuit.
H.
SAFETY SYSTEM RESPONSES:
There were no demands for safety system actuations during this event.
II.
CAUSE OF EVENT
The inoperable 1A EDG is documented in station condition report number CR-2011-008708.
The penetration around the 1A2 combustion air intake pipe on the 80 foot level of the 1A Diesel Generator Building was unable to perform its design function of being leak tight. Dripping water penetrated the 1A EDG 1A2 engine speed switch connector causing the speed switch circuit to short. This shorted speed switch caused the field flash circuit to attempt to flash the 1A EDG.
Since the generator was not turning, a field was not established and the field flash circuit protective features were enabled. Because these protective features were enabled, the field flash circuit would not have been available for subsequent EDG starts. An evaluation has determined that the most likely root cause(s) are limited to improper installation, manufacturing defect, degradation, or inadequate original design considerations of the penetration around the 1A2 combustion air intake pipe.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REV YEAR NUMBER NO.
Calvert Cliffs Nuclear Power Plant, Unit 1 05000 317 2011
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of 06 The subject condition is applicable to one of the four emergency power sources, the 1A EDG which is a Societe Alsacienne De Constructions Mecaniques De Mulhouse design diesel generator. The three other EDGs are not susceptible to this condition as this is the only location in the plant for this type of penetration with this specific configuration of boot seals that is open to atmospheric conditions.
III.
ANALYSIS OF EVENT
While performing a root cause analysis for the inoperability of the 1A EDG, it was determined that the IA EDG may have been inoperable from original construction (1996).
This event is reportable in accordance with the following:
10 CFR 50.73(a)(2)(i)(B); "Any operation or condition which was prohibited by the plant's Technical Specifications."
Since the 1A EDG may have been inoperable from original construction, the following occurrences are examples of situations when the site unknowingly exceeded the Technical Specification allowed completion times.
" The 1A EDG may have been inoperable for a period of over 14 years.
- The 1 B EDG was removed from service for scheduled maintenance at 0130 on October 18, 2010 and was returned to service at 1010 on October 22, 2010, a period of over 104 hours0.0012 days <br />0.0289 hours <br />1.719577e-4 weeks <br />3.9572e-5 months <br />.
" The 2A EDG was removed from service to investigate an unplanned start at 1827 on November 16, 2008 and was returned to service at 1912 on November 17, 2008, a period of over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. With both Train A EDGs inoperable, all Train A site battery chargers and both Train A 125 VDC busses were inoperable, which should have resulted in entry into Technical Specification 3.0.3 on both units.
The Technical Specifications require one EDG from the other unit to be capable of supplying power to the Control Room Emergency Ventilation System and the Control Room Emergency Temperature System. The 1A EDG provides this Technical Specification function for Unit 2. The 2B EDG was removed from service at 0200 on November 8, 2010 for scheduled maintenance and was returned to service at 0100 on November 11, 2011, a period of 71 hours8.217593e-4 days <br />0.0197 hours <br />1.173942e-4 weeks <br />2.70155e-5 months <br />.
The above conditions existed for a time longer than the completion time allowed by their respective Technical Specifications. Therefore, this event is reportable pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(i)(B).U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE i
SEQUENTLAL I
REV YEAR NUMBER NO.
Calvert Cliffs Nuclear Power Plant, Unit 1 05000 317 2011
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10 CFR 50.73(a)(2)(ii)(B), "Any event or condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degraded plant safety."
Chapter 14 of the Calvert Cliffs Updated Final Safety Analysis Report (Safety Analysis) presents analytical evaluations of the Nuclear Steam Supply System response to postulated disturbances in process variables and to postulated malfunctions or failure of equipment.
Some postulated disturbances analyze the most limiting failure of equipment.
In some analyses, failure of one EDG is assumed. However, there are no instances where the failure of both EDGs is assumed.
Therefore this event is reportable pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(ii)(B).
10 CFR 50.73(a)(2)(v)(D), "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident."
There are occurrences following construction of the 1A EDG when both the 1A and 1B EDGs were simultaneously inoperable. No redundant equipment in the same system was operable and available to perform the required safety function. Therefore this event is reportable pursuant to the reporting requirements specified in 10 CFR 50.73(a)(2)(v)(D).
There were no actual nuclear safety consequences incurred from this event. For periods when both the 1A and 1 B EDGs were out-of-service, Unit 1 was more susceptible to a Station Blackout (SBO) event. The SBO diesel generator is designed to provide a power source capable of starting and supplying the essential loads necessary to safely shutdown one unit and maintain it in a safe shutdown condition during an SBO event.
The Nuclear Regulatory Commission Performance Indicator for Safety System Functional Failures for Unit 1 rises from 0.0 to 1 as a result of this event and will remain in the green band.
No other Nuclear Regulatory Commission Performance Indicators were impacted.
A Significance Determination Process evaluation determined that the risk incurred by operating Unit 1 with the 1A EDG in this degraded condition is as follows: Integrated Conditional Core Damage Probability and Integrated Conditional Large Early Release Probability are 7E-07 and 7E-08, respectively. The risk incurred by operating Unit 2 with the 1A EDG in this degraded condition is as follows: Integrated Conditional Core Damage Probability and Integrated Conditional Large Early Release Probability are 6E-07 and 4E-08, respectively.
IV. CORRECTIVE ACTIONS
A.
ACTION TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL STATUS:
- 1.
The 1A2 engine speed switch assembly was cleaned, dried, and inspected.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL I
REV YEAR NUMBER NO.
Calvert Cliffs Nuclear Power Plant, Unit 1 05000 317 2011
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of 06 B.
ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:
- 1.
Curbs have been installed to deflect water on the floor from reaching the penetration seals.
- 2.
The combustion inlet piping penetrations for the 1A Diesel Generator Building between the 80 foot and 66 foot elevations will be repaired to ensure the penetrations are leak tight.
If information is subsequently developed, that would significantly affect a reader's understanding or perception of this event, a supplemental licensee event report (LER) will be submitted.
V. ADDITIONAL INFORMATION
A.
FAILED COMPONENTS:
- 1.
The 1A EDG Building penetration seals were manufactured by PCI - Promatec.
- 2.
The 1A2 Engine Speed Switch Assembly was manufactured by Moisy-Servat.
- 3.
The 1A EDG was manufactured by Societe Alsacienne De Constructions Mecaniques De Mulhouse.
B.
PREVIOUS LERs ON SIMILAR EVENTS:
A review of Calvert Cliffs' events during the past several years was performed. No previous LERs were identified that involved the same underlying concern or reason for this event.
C.
THE ENERGY INDUSTRY IDENTIFICATION SYSTEM (EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:
IEEE 803 IEEE 805 COMPONENT EIIS FUNCTION SYSTEM ID 1A EDG DG EK 1A2 Engine Speed Switch Assembly SIS EK 1A EDG Building SEAL NB D.
SPECIAL COMMENTS:
None