05000341/LER-2012-001, Regarding Loss of Shutdown Cooling Due to a Voltage Transient
| ML12163A361 | |
| Person / Time | |
|---|---|
| Site: | Fermi  (NPF-043) |
| Issue date: | 06/08/2012 |
| From: | Plona J Detroit Edison, DTE Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-12-0038 LER 12-001-00 | |
| Download: ML12163A361 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 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)(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 |
| 3412012001R00 - NRC Website | |
text
Joseph H. Plona Site Vice President 6400 N. Dixie Highway, Newport, MI 48166 Tel:
734.586.5910 Fax: 734.586.4172 10 CFR 50.73 June 8, 2012 NRC-12-0038 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001
Reference:
Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43
Subject:
Licensee Event Report (LER) No. 2012-001 Pursuant to 10 CFR 50.73(a)(2)(v)(B), Detroit Edison is submitting the enclosed LER No. 2012-001, Loss of Shutdown Cooling Due to a Voltage Transient.
No commitments are being made in this LER.
Should you have any questions or require additional information, please contact Mr. Rodney W. Johnson of my staff at (734) 586-5076.
Sincerely, Enclosure cc: NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 4, Region III Regional Administrator, Region III Supervisor, Electric Operators, Michigan Public Service Commission
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: No. 3150-0104 Expires 10/31/2013 (10-2010)
Estimated
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Fermi2 05000341 1 OF 4
- 4. TITLE Loss of Shutdown Cooling Due to a Voltage Transient
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV I FACILITY NAME DOCKET NUMBER NUMBER NO.
MONTH DAY YEAR 05000 04 11 2012 2012 001 00 06 08 2012 FACILITY NAME DOCKET NUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT SUBMITTED PURSU ANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
Q 20.2201(b) j 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) 20.2201(d) 020.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) j 50.73(a)(2)(viii)(A) 5 20.2203(a)(1) 020.2203(a)(4) 50.73(a)(2)(ii)(B) 050.73(a)(2)(viii)(B) 20.2203(a)(2)(i)
E 50.36(c)(1)(i)(A) 050.73(a)(2)(iii)
E 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 020.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A) 050.73(a)(2)(iv)(A) 0 50.73(a)(2)(x) 020.2203(a)(2)(iii) 50.36(c)(2)
Q 50.73(a)(2)(v)(A) 073.71(a)(4) 0 Percent 020.2203(a)(2)(iv) 50.46(a)(3)(ii) x 50.73(a)(2)(v)(B) 073.71(a)(5) 020.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C)
Q OTHER Q 20.2203(a)(2)(vi) 050.73(a)(2)(i)(B)
Q 50.73(a)(2)(v)(D)
Specify in abstract below or In NRC Form 366A
- 12. LICENSEE CONTACT FOR THS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Fermi 2 / Joseph M. Pendergast - Principal Engineer, Nuclear Licensing (734) 586 - 1682CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION L YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On April 11, 2012, at approximately 1807 EDT, with the plant in Mode 5 during Refueling Outage 15, a common suction shutdown cooling inboard containment isolation valve closed in response to a voltage transient. The 'A' Residual Heat Removal pump tripped as a result of the valve closure. The valve closure resulted in an interruption of shutdown cooling, the primary means of decay heat removal for approximately 11 minutes. During this period, there was no measurable increase in reactor temperature. The Fuel Pool Cooling system was in service at that time and was capable of removing decay heat. The event occurred during a restoration of power to Division 2 Bus 65E from the 64T cross tie breaker when a voltage transient occurred due to a fault on Bus 65E. The fault was the result of an improper safety tagging clearance that left a grounding truck in place during the power restoration. The fault caused a Group 4 isolation of the El 150F009 shutdown cooling common suction valve. Abnormal Operating Procedure 20.205.01, Loss of Shutdown Cooling, was entered, the Group 4 isolation was reset and Shutdown Cooling was restored at 1818 EDT. Related human performance issues were addressed through additional operator just in time training. There were no safety consequences to this event.
NRC FORM 366 (10-2010)
Initial Plant Conditions
Mode 5
Reactor Power 0 percent Description of the Event On April 11, 2012, at approximately 1807 EDT, with the plant in Mode 5 during Refueling Outage 15 (RF15) and with Shutdown Cooling (SDC) in operation, the El 150F009, "Division 1 and 2 Shutdown Cooling Inboard Containment Isolation Valve," automatically closed. The 'A' Residual Heat Removal (RHR) [BO] pump tripped as a result of the valve closure. The valve closure resulted in an interruption of SDC, the primary means of decay heat removal for approximately 11 minutes. During this period, there was not a measurable increase in reactor temperature. The calculated time to boil was approximately 23.1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
During the restoration of the Bus 65E Safety Tagging Record (STR), operators did not identify that a ground truck was still installed in position 65E-E4. When attempting to energize Division 2 Bus 65E from Division 1 through the 64T crosstie breaker and the 65E-E9 breaker per System Operating Procedure (SOP) 23.321, "Engineer Safety Features Auxiliary Electrical Distribution System," the breaker [BKR] immediately tripped open. A voltage transient occurred due to a fault on Bus 65E which resulted in a Group 4 (Shutdown Cooling/Head Spray) isolation (closure) of the El150F009 shutdown cooling suction valve. The 'A' RHR pump tripped on loss of suction flow path as the shutdown cooling suction valve closed.
The Fuel Pool Cooling system was in service at the time of the event and was capable of removing decay heat.
The Reactor Cavity was flooded for refueling and the gates between the Reactor Cavity and the Fuel Pool were removed. Abnormal Operating Procedure 20.205.01, Loss of Shutdown Cooling, was entered, the Group 4 isolation was reset, and SDC was restored at 1818 EDT.
This event was reported to the NRC as an 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> event under 10 CFR 50.72 (b)(3)(v)(B), event or condition that at the time of discovery could have prevented fulfillment of a safety function of structures or systems that are needed to remove residual heat, as documented in event notification 47826.
Significant Safety Consequences and Implications
For the duration of this event, Fuel Pool Cooling and Cleanup (FPCCU) was in-service. The Reactor cavity was flooded and the gates between the Fuel Pool and the Reactor Cavity were removed for refueling. The RHR shutdown cooling was available for the duration of this event. There were no component failures associated with this event that would have prevented the valve from being reopened and the system from being restarted. All of the affected equipment responded as designed to isolate the containment and protect safety equipment.
Therefore, there were no safety consequences and no effect on public health and safety as a result of this event.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR T SEQUENTIAL REVISION Fermi 2 05000341 2012 NUMBER NUMBER 3 OF 4 I
001 00 This event is being reported as an event or condition that at the time of discovery could have prevented fulfillment of a safety function of structures or systems needed to remove residual heat under 10 CFR 50.73 (a)(2)(v)(B).
Cause of the Event
The STR was not properly cleared before authorizing the performance of the SOP to energize Bus 65E from the maintenance tie breaker. Procedure 23.300, Breaker Operations, and Operations Department Expectation (ODE) 19, Safety and Configuration Tagging were not correctly implemented by operations personnel. A "Ground Truck Installed" sign that should have been placed on the breaker cubicle for 65E-E4 was not in place as required by 23.300 Section 6.5. The STR was also not completely cleared before authorizing the performance of the SOP to energize the bus from the 64T maintenance tie breaker. A review of the STR and the equipment walkdown prior to implementation of the STR did not identify that the ground truck remained installed. Strict compliance with procedures 23.300 and ODE-19 along with appropriate self checking would have ensured the standards were met, and could have prevented the problem.
Corrective Actions
The Group 4 isolation signal was reset, the SDC common suction valve was reopened, and SDC was established in 11 minutes.
The station implemented several equipment control tools to avoid a repeat event or reoccurrence. A checklist was developed for the preparer and reviewer of STRs. The requirements of actions to be performed by reviewers of STRs were reinforced by Operations Management during crew briefings and further reinforced during Just In Time Training. Requirements were established for licensed operators to conduct a walkdown (eyes on) of the bus prior to energization to insure bus is ready for current. Additional operator awareness tools were used to convey equipment status including the use of placards at the point of ground installation and in the Main Control Room.
Oil samples were taken April 12, 2012, on System Service Transformer (SST) 64 and House Transformer 1 and analyzed to ensure the transformers were not degraded by the temporary short to ground. Oil Sample results were the same as for the samples taken in March, 2012; therefore, there was no damage to the transformers.
Technical Evaluation TE-R14-12-037 was performed for a 3 phase to ground fault analysis to confirm that the postulated short circuit current was within the ratings of breakers 64T, 65E-E9, 65E-E12 and buses 65E (R1400SO01E) and 64T cable bus (RI 100S061) when Division 2 Bus 65E is fed by maintenance tie breaker 64T.
The ground fault current was determined to be within the equipment's momentary capabilities and the breaker's interrupting capabilities.
Additionally, a detailed walkdown of bus 65E breaker positions was performed, which did not identify any signs of damage as a result of the event.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL REVISION Fermi2 05000341 NUMBER NUMBER 4 OF 4 2012 001 00
Additional Information
A. Failed Component:
None identified.
B.
Previous Licensee Event Reports (LERs) on Similar Problems:
No similar events were identified.