05000483/LER-2008-001, Containment Cooler Inoperability
| ML081490463 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 05/22/2008 |
| From: | Diya F AmerenUE |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| ULNRC-05512 LER-08-001-00 | |
| Download: ML081490463 (9) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 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 |
| 4832008001R00 - NRC Website | |
text
AmerenUE Callaway Plant PO Box 620 Fulton, MO 65251 May 22, 2008 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop P1-137 Washington, DC 20555-0001 ULNRC-05512 WAmemon UF Ladies and Gentlemen:
DOCKET NUMBER 50-483 CALLAWAY PLANT UNIT 1 UNION ELECTRIC CO.
FACILITY OPERATING LICENSE NPF-30 LICENSEE EVENT REPORT 2008-001-00 Containment Cooler Inoperability The enclosed licensee event report is submitted in accordance with 10CFR50.73(a)(2)(i)(B) and 10CFR50.73(a)(2)(vii) to report inoperability of the containment coolers.
This letter does not contain new commitments.
Fa"-d M. Diya Plant Director FMD/CSP/nls Enclosure H
a subsidiary ofAmeren Corporation
ULNRC-05512 May 22, 2008 Page 2 cc:
Mr. Elmo E. Collins, Jr.
Regional Administrator U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Senior Resident Inspector Callaway Resident Office U.S. Nuclear Regulatory Commission 8201 NRC Road Steedman, MO 65077 Mr. Mohan C. Thadani (2 copies)
Licensing Project Manager, Callaway Plant Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Mail Stop O-8G14 Washington, DC 20555-2738
ULNRC-05512 May 22, 2008 Page 3 Index and send hardcopy to QA File A160.0761 Hardcopy:
Certrec Corporation 4200 South Hulen, Suite 422 Fort Worth, TX 76109 (Certrec receives ALL attachments as long as they are non-safeguards and may be publicly disclosed.)
LEREvents @inpo.org (must send the WORD version of the LER to this address)
Electronic distribution for the following can be made via LER ULNRC Distribution:
C. D. Naslund A. C. Heflin F. M. Diya T. E. Herrmann L. H. Graessle G. A. Hughes S. A. Maglio S. L. Gallagher L. M. Belsky (NSRB)
T. B. Elwood D. E. Dumbacher (NRC)
B. A. Brook (WCNOC)
Ms. Diane M. Hooper (WCNOC)
Mr. Dennis Buschbaum (TXU)
Mr. Scott Bauer (Palo Verde)
Mr. Stan Ketelsen (PG&E)
Mr. Scott Head (STP)
Mr. John O'Neill (Pillsbury Winthrop Shaw Pittman LLP)
Missouri Public Service Commission Records Center (INPO)
I NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO.3150-0104 EXPIRES: 06/30/2007 (6-2004)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
AG
- 3. PAGE Callaway Plant Unit 1 05000483 1 OF 6
- 4. TITLE Containment Cooler Inoperability
- 5. EVENT DATE
- 6. LER NUMBER _
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR NUMBER NO.
FACILITY NAME DOCKET NUMBER 03 26 2008 2008
- - 001 00 5
22 20081
- 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) 0 50.73(a)(2)(vii)
El 20.2201(d)
E] 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
E] 20.2203(a)(1)
E] 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
E] 50.73(a)(2)(viii)(B)
E] 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
[I 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL [I 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)
E] 20.2203(a)(2)(iii)
El 50.36(c)(2)
E] 50.73(a)(2)(v)(A)
El 73.71(a)(4)
E] 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii)
[I 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 E] 20.2203(a)(2)(v)
[E 50.73(a)(2)(i)(A)
[E 50.73(a)(2)(v)(C)
E] OTHER El 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
[E 50.73(a)(2)(v)(D)
Specify in Abstract below or in SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES Per Callaway Technical Specification (T/S) 3.6.6, "Containment Spray and Cooling Systems," two containment cooling trains and two containment spray trains are required to be operable in Modes 1, 2, 3, and 4. One of the primary functions of these systems is to remove sufficient heat energy and subsequent decay heat from the containment atmosphere following a loss-of-coolant accident (LOCA) or main steam line break (MSLB) to maintain the containment pressure below design values. The trains are completely redundant, and for each cooling train two coolers are provided and required. One train consists of the "A" and "C" coolers; the other cooling train consists of the "B" and "D" coolers. A cooler consists primarily of a cooling coil, damper, and fan. The fans can be run in fast speed or slow speed during plant operation to maintain containment pressure and temperature within required operating limits. However, upon receipt of an actuation signal (in the event of an accident) the fans are designed to automatically start or restart in slow speed for their accident mitigation function.
Another relevant feature of the containment coolers is that the fan motors are equipped with thermal overload protection to prevent motor damage from a mechanical overload. Separate overload devices are provided for slow-and fast-speed operation. Subsequent to a thermal overload protective trip, operator action is required to reset the trip before the cooler can be restarted.
At 0709 on March 26, 2008, containment pressure was elevated but within the allowable range as containment purge was not available to reduce containment pressure. Control Room operators shifted all four containment cooler fans to fast speed in order to reduce containment pressure. A high vibration alarm, computer point GNY0007, was subsequently received on the "A" containment cooler (SGN01 A),
and it was decided to shift the fan to slow speed. At 0736, the fan was stopped per procedure OTN-GN-00001, "Containment Cooling and CRDM Cooling," in preparation for re-starting it in slow speed.
When the fan was stopped, an Engineered Safety Function Actuation Signal (ESFAS) status panel alarm was received for loss of control power to SGN01A. Loss of indication also occured On the fan handswitch.
The loss of control power to SGN01 A occurred due to the fast-speed thermal overload contact opening.
The contact opened due to relatively high motor loading coincident with a fan speed change. The increased motor loading was due to the increased density of the air being moved through the fan. At (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17) automatically restart in slow-speed even if the fast-speed thermal overloads have tripped. This modification resolved the operability concern of the containment coolers since it allows them to perform their safety design function of starting (or re-starting) and running in slow speed to mitigate the consequences of an accident.
IV. PREVIOUS SIMILAR EVENTS
Previous occurrences of the containment coolers tripping during fast-speed operation were documented during the Startup Test Program at Callaway in 1983. Actions taken to address the tripping included replacement of the thermal overloads with higher ratings and changes to the control circuitry for the coolers.
A trip of one of the coolers occurred in 1986, and as corrective action for that event, new overloads with trip times in the longer portion of their allowable range were installed. Shortly after that, in 1987, a precaution was added to the operating procedure regarding fast-speed operation of the coolers during conditions of high containment pressure and low cooling water, noting that operation under such condition may cause the coolers to operate near the thermal overload setpoint(s). No further occurrences were documented until the trip of the "A" cooler on March 26, 2008.
For the trip that occurred on March 26, 2008 it should be noted that, at the time of the event, containment pressure was higher than normal (but still within the limit specified in the Technical Specifications) because containment purge was unable to be operated due to the extended inoperability of a purge exhaust process radiation monitor. (Per Callaway TS 3.3.6, "Containment Purge Isolation Instrumentation," the containment purge supply and exhaust valves must be closed when an inoperable containment purge exhaust radiation is not restored within the allowed outage time specified in the Required Action.) In addition, due to time of the year for this event (i.e., early spring), cooling water temperature was low. These factors combined to increase the load on the containment cooler fans (as previously explained) to higher than typical levels.
V.
ADDITIONAL INFORMATION
The system and component codes listed below are from the IEEE Standard 805-1984 and IEEE Standard 803A-1984 respectively.
System:
BK - Containment Fan Cooling System Component: 49
- - Relay, Machine or Transformer Thermal Component: FAN - Fan