05000341/LER-2013-003, Regarding Loss of Secondary Containment Function Due to Exceedance of Technical Specification Required Vacuum Pressure
| ML14022A266 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 01/22/2014 |
| From: | Conner J DTE Electric Company, DTE Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-14-0004 LER 13-003-00 | |
| Download: ML14022A266 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 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)(i)(B), Prohibited by Technical Specifications |
| 3412013003R00 - NRC Website | |
text
J. Todd Conner Site Vice President DTE Energy Company 6400 N. Dexe Highway, Newport, MI 43166 Tel: 734.586.4849 Fax: 734.586.295 Emheail: conneij@dteenergy.com DTE Energy-January 22, 2014 10 CFR 50.73 NRC-14-0004 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. 2013-003 Pursuant to 10 CFR 50.73 (a)(2)(v)(C), DTE Electric Company is submitting LER No.
2013-003, Loss of Secondary Containment Function Due to Exceedance of Technical Specification Required Vacuum Pressure.
No commitments are being made in this LER.
Should you have any questions or require additional information, please contact Mr.
Zackary W. Rad of my staff at (734) 586-5076.
Sincerely, Enclosure cc:
NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III Michigan Public Service Commission Regulated Energy Division (kindschlamichigan.gov)
Enclosure to NRC-14-0004 Fermi 2 NRC Docket No. 50-341 Operating License No. NPF-43 LER 2013-003, Loss of Secondary Containment Function Due to Exceedance of Technical Specification Required Vacuum Pressure
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 3
- 4. TITLE Loss of Secondary Containment Function Due to Exceedance of Technical Specification Required Vacuum Pressure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV M
FACILITY NAME DOCKET NUMBER MN DY E
NUMBER NO.
MONTH DAY YEAR 05000 11 24 2013 2013 003 00 01 22 2014 FACILITYNAME DOCKETNUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT SUBMITTED PURSU ANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
Q 20.2201(b) 0 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)
E 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A)
J 50.73(a)(2)(viii)(A)
E 20.2203(a)(1) 020.2203(a)(4) j 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A)
J 50.73(a)(2)(iii)
J 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL E 20.2203(a)(2)(ii)
E 50.36(c)(1)(ii)(A) 050.73(a)(2)(iv)(A) 050.73(a)(2)(x) j 20.2203(a)(2)(iii) j 50.36(c)(2)
Q 50.73(a)(2)(v)(A) 0 73.71(a)(4) 100 Percent 020.2203(a)(2)(iv) 050.46(a)(3)(ii)
E 50.73(a)(2)(v)(B) 073.71(a)(5)
QJ20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) x 50.73(a)(2)(v)(C) 0 OTHER E
20.2203(a)(2)(vi)
E 50.73(a)(2)(i)(B)
J 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 / Alan L Hassoun - Supervisor, Nuclear Licensing (734) 586 - 4287CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX B
VA TRP S039 Y
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION f
YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
X NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On November 24, 2013, at approximately 00:01 hours EST, during normal plant operations, the non-safety related Reactor Building Heating Ventilation and Air Conditioning (RBHVAC) system tripped on low steam coil heater temperature. Secondary Containment differential pressure exceeded the Technical Specification (TS) Surveillance Requirement limit of -0.125 inches water column (WC), reaching a maximum of +0.08 inches WC. At 00:04 hours EST, the Standby Gas Treatment System (SGTS) was started and Secondary Containment differential pressure decreased to less than -0.125 inches WC. The RBHVAC system tripped due to lack of steam flow through a heating coil caused by inadequate draining of the downstream steam trap. Investigation revealed the presence of some corrosion and a cracked drain seat in the associated steam drain. The degraded steam drain was then replaced and tested. RBHVAC was returned to normal operation and SGTS was shutdown and returned to standby at 23:46 hours EST on November 24, 2013. Preventive maintenance is being scheduled to inspect, and clean or replace the RBHVAC steam traps and strainers.
With Secondary Containment differential pressure exceeding -0.125 inches WC, TS Surveillance Requirement 3.6.4.1.1 was not met and Secondary Containment was declared inoperable. No other degradation of Secondary Containment existed at the time of the event. This event was reported per the guidance of NUREG-1022, Rev. 3, section 3.2.7, as a loss of Safety Function. There were no radiological releases associated with this event.
NRC FORM 366 (10-2010)
Initial Plant Conditions
Mode 1
Reactor Power 100 percent Description of the Event On November 24, 2013, at approximately 00:01 hours EST, the non-safety related Reactor Building Heating Ventilation and Air Conditioning (RBHVAC) [VA] system tripped due to improper drainage of a steam. coil heater [CL] through its steam trap. Secondary Containment [NH] differential pressure rose above -0.125 inches water column (WC), reaching a maximum of +0.08 inches WC. At 00:04 hours EST, the Standby Gas Treatment System (SGTS) was manually started and Secondary Containment differential pressure decreased to less than
- - 0.125 inches WC.
Technical Specification Surveillance Requirement (SR) 3.6.4.1.1 verifies that Secondary Containment vacuum is greater than or equal to 0.125 inches of vacuum water gauge. Limiting Condition for Operation 3.6.4.1, Condition B, Secondary Contaimnent inoperable was entered due to not meeting SR 3.6.4.1.1, and later exited when Secondary Containment pressure was restored to less than -0.125 inches WC. The Emergency Operating Procedures (EOPs) were entered based on high Secondary Containment differential pressure and later exited at 00:09 hours EST.
The RBHVAC system has 14 steam coil heaters and 14 corresponding low temperature switches. The switches monitor the temperature of the heater coils to ensure they do not freeze. If any switch trips on low temperature, the RBHVAC system automatically trips. In this event, one of the switches tripped on low temperature (35°F decreasing) causing a trip of the RBHVAC system.
Upon determination of the cause of the trip and replacement of the steam trap, the RBHVAC system was restarted and the SGTS shutdown at 23:46 hours EST on November 24, 2013.
The loss of Secondary Containment function is reportable under 10 CFR 50.73(a)(2)(v)(C) as an event or condition that could have prevented the fulfillment of a safety function needed to control the release of radioactive material. An 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> NRC event notification (No. 49575) was previously made to the NRC based on meeting the reporting criteria of 10 CFR 50.72(b)(3)(v)(C).
Significant Safety Consequences and Implications
The purpose of SR 3.6.4.1.1 is to verify Secondary Containment integrity. This SR ensures that the Secondary Containment boundary is sufficiently leak tight to preclude exfiltration under expected wind conditions.
The non-safety related RBHVAC system is not relied upon to mitigate consequences of an accident. Secondary Containment, in conjunction with the SGTS, is designed to minimize release of radioactive material which may result from an accident.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE 0YEAR SEQUENTIAL REVISION Fermi 2 05000341 l
NUMBER NUMBER 3 OF 3 I
I 2013 003 00 The two principal accidents for which Secondary Contaimnent integrity is assumed are a loss of coolant accident (LOCA) and a fuel handling accident (FHA). Neither of these accidents occurred coincident with this event.
The SGTS is designed to start automatically to maintain the reactor building at a negative pressure relative to the outside atmosphere during transient and accident conditions. The SGTS can also be manually started from the Main Control Room [NA]. During this event, Division 1 of SGTS was manually started (no transient or accident had occurred that would automatically start SGTS) and restored the required Secondary Containment vacuum approximately 3 minutes after RBHVAC tripped. There were no radiological releases associated with this event.
Therefore, this event did not pose an actual threat to the health and safety of the public.
Cause of the Event
RBHVAC tripped on low heater coil temperature due to lack of steam flow through a heating coil caused by improper draining of the downstream steam trap. Investigation revealed corrosion and a cracked drain seat in the associated steam drain.
Corrective Actions
The malfunctioning heating coil steam trap was replaced and tested. The RBHVAC system was returned to normal operation. Secondary Containment differential pressure was stabilized at less than -0.125 inches WC, and the SGTS was shutdown at 23:46 hours EST on November 24, 2013.
Since this event was potentially caused by a corrosion related failure, preventive maintenance is being scheduled to inspect, and clean or replace the RBHVAC steam traps and strainers.
Additional Information
A.
Failed Component: Steam Drain Component: Steam Trap [TRP] T4100D043N Function: Discharge condensate as it is formed Manufacturer: SPIRAX SARCO Model Number: FT-15, 3/4"- 1" Failure Cause: Corrosion and a cracked drain seat B.
Previous Licensee Event Reports (LERs) on Similar Problems:
LER 2013-001 also involved a loss of Secondary Containment function due to an RBHVAC system equipment malfunction. However, the cause of that event was related to damper sequencing. Therefore, the corrective actions for that event would not have precluded this event.