05000446/LER-2003-004, Regarding Containment Pressure Channel Inoperable Due to Random Electronic Failure
| ML033640492 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 12/22/2003 |
| From: | Blevins M TXU Electric, TXU Generation Co, LP |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CPSES-200302512, TXX-03197 LER 03-004-00 | |
| Download: ML033640492 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2) |
| 4462003004R00 - NRC Website | |
text
STxU TXU Energy Comanche Peak Steam Electric Station P.O.Box 1002 (EO1)
Glen RoseTX 76043 Tel: 254 897 5209 Fax: 254 897 6652 mike.blevins@txu.com Mike Blevins Senior Vice President & Principal Nuclear Officer Ref:
CPSES-200302512 Log# TXX-03197 File # 10010 December.22, 2003 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NO. 50-446 CONDITION PROHIBITED BY TECHNICAL SPECIFICATIONS LICENSEE EVENT REPORT 446/03-004-00 Gentlemen:
Enclosed is Licensee Event Report (LER) 03-004-00 for Comanche Peak Steam Electric Station Unit 2, "Containment Pressure Channel Inoperable Due to Random Electronic Failure."
This communication contains no new licensing basis commitments regarding CPSES Units 1 and 2.
Sincerely, TXU Generation Company LP By:
TXU Generation Management Company LLC, Its General Partner tA I
Mike Blevins GLWgm Enclosure c:
B. S. Mallett, Region IV W. D. Johnson, Region IV M. C. Thadani, NRR Resident Inspectors, CPSES A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak
- Diablo Canyon
- Palo Verde
- South Texas Project
- Wolf Creek
Enclosure to TXX-03197 NRC FORM 366 US. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 31504104 (7-2001)
EXPIRES 171h112004
, the NRC may not conduct or sponsor aNd a person is not required to respond to. the informatn collection.
Facility Name ()
Docket Number (2)
Page (3)
COMANCHE PEAK ST ELECTRIC STATION UNIT 2 05000446 1 OF S Titl (4)
CONDITION PROHIBITED BY TECHNICAL SPECIFICATIONS Event Dte (
l LER Numbier (6) l Report Date M Other Faciities Involved (S)
Month D y Yew t yea llail Sequentialii Revison Month Day Year Facility Name Nure Nmber Nme N/A 05000 11 05 0
03 004 0
12 2203 05000 operating Turepoit s submitted pursuant to the recrure x of 10 FR : (Cock all that apply) 0 )-
Mode MR) 1
_ 20.2201(b) 20.2203(aX3)i) 50.73(aX2XiXC) 50.73(a)(2Xvii)
Power 20.2201(d) 20.2203(a)(3i)
S0.73(aX2XiiXA) 50.73(a)(2XviiiXA)
Lavnl 99 20.2203(aXI) 20.2203(aX4)
= 50.73(aX2Xii)(13) 50.73(a2)(viiiXB) 20.2203(aX2Ki) 50.36(cX2(i)(A) 50.73(a02Xiii)
S0.73(aX2Xix)(A) 20.2203(a)(2)(ii) 50.36(cXI)(iiXA)
S0.73(aX2XivXA) 50.72(aX2Xx) 20.2203(aX2Xiii) 50.36(cX2) 50.73(aX2X)(A) 73.71(a)(4) 20.2203(aX2)(iv)
S0.46(a)l3)(ti)
SO.73(aX2)(v)(B) 73.71(a)(5) 20.2203(aX2)(v) 50.73(a)(2Xi)(A) 50.73(a)(2)(vXC)
OTHER 20.2203(aX2)(vi)
X 50.73(a)(2)(i)(B) 50.73(aX2XvMD)
Specify in Abstract below or in =
(If more space ileres use addinal copies of NRC Forn 366A) (17)
L DESCRIPTION OF REPORTABLE EVENT A.
REPORTABLE EVENT CLASSIFICATION
Any operation or condition prohibited by the plant's Technical Specifications.
B.
PLANT OPERATING CONDITIONS PRIOR TO THE EVENT On November 5, 2003, Comanche Peak Steam Electric Station (CPSES) Unit 2 was in Mode 1, Power Operation, operating at approximately 99 percent power following the Unit 2 seventh refueling outage.
C.
STATUS OF STRUCTURES, SYSTEMS, OR COMPONENTS THAT WERE INOPERABLE AT THE START OF THE EVENT AND THAT CONTRIBUTED TO THE EVENT There were no inoperable structures, systems, or components that were inoperable at the start of the event that contributed to the event.
D.
NARRATIVE SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On November 5, 2003, CPSES Unit 2 was in Mode 1, Power Operation, operating at approximately 99 percent power following the Unit 2 seventh refueling outage. During routine control board [EIIS:(NA)(MCBD)] observations, Operators (utility, licensed) in the Unit 2 Control Room noted that one of the four Engineered Safety Feature Actuation System (ESFAS) intermediate range containment pressure channels (channel 2-P-0935)
[EIIS:(JE )(CHA)] was reading approximately 0.7 psig low with respect to the other channels. At 0950, the channel was declared inoperable per Technical Specification (TS) 3.3.2. This TS requires that the inoperable channel be placed in bypass or trip within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> or the affected Unit must be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Mode 4 within 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />. Review of the plant computer data indicated that the affected channel had been inoperable from 0530 on November 3, 2003 to 1042 on November 5, 2003, for a total of 53 hours6.134259e-4 days <br />0.0147 hours <br />8.763227e-5 weeks <br />2.01665e-5 months <br /> and 12 minutes. This exceeded the TS completion time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> to be in Mode 3. Therefore, a reportable violation of Technical Specifications occurred.
(If oe space i required, use additional copies of NRC R=m 366A) (17)
E.
THE METHOD OF DISCOVERY OF EACH COMPONENT OR SYSTEM FAILURE, OR PROCEDURAL OR PERSONNEL ERROR Operations personnel (utility, licensed) discovered during routine control board observations and review of plant computer data that intermediate range containment pressure channel 2-P-0935 was inoperable.
II.
COMPONENT OR SYSTEM FAILURES A.
FAILURE MODE, MECHANISM, AND EFFECTS OF EACH FAILED COMPONENT Intermediate range containment pressure channel 2-P-0935 failed reading low (approximately 0.7 psig).
B.
CAUSE OF EACH COMPONENT OR SYSTEM FAILURE Intermediate range containment pressure channel 2-P-0935 failed reading low due to a degraded power supply circuit card. The failure of the power supply circuit card was determined to be a random electronic component failure.
C.
SYSTEMS OR SECONDARY FUNCTIONS THAT WERE AFFECTED BY FAILURE OF COMPONENTS WITH MULTIPLE FUNCTIONS Failure of intermediate range containment pressure channel 2-P-0935 affects the Safety Injection (SI), Containment Spray (CT), and Main Steam Line Isolation (MSLI) ESFAS functions.
D.
FAILED COMPONENT INFORMATION
Manufacturer - Westinghouse Model - NLP Card Group 2, serial number 803561 Enclosure to TXX-03197Us NUCLEAR REGULATORY COMMISSION 11-2001)
LICENSEE EVENT REPORT (LER)
Farilky Name (1)
LER Number (6)Pe(3)
Yewr Sequnal I Revibn COMANCHE PEAK STEAM CTRIC STATION UNIT 2 46 3
NumberM 4 OF NARRA E (if more spe ig mquwed.
use addaoral wpws ofNRC Rum 366)
(.
m. ANALYSIS OF TLE EVENT A.
SAFETY SYSTEM RESPONSES THAT OCCURRED Not applicable - No safety system responses occurred as a result of this event.
B.
DURATION OF SAFETY SYSTEM TRAIN INOPERABIELITY Based on review of plant computer data, intermediate range containment pressure channel 2-P-0935 was found to have been inoperable from 0530 hours0.00613 days <br />0.147 hours <br />8.763227e-4 weeks <br />2.01665e-4 months <br /> on November 3, 2003 until 1042 hours0.0121 days <br />0.289 hours <br />0.00172 weeks <br />3.96481e-4 months <br /> on November 5, 2003 (a total of 53 hours6.134259e-4 days <br />0.0147 hours <br />8.763227e-5 weeks <br />2.01665e-5 months <br /> and 12 minutes).
C.
SAFETY CONSEQUENCES AND IMPLICATIONS
The containment pressure sensing channels are necessary for the SI, MSLI, and CT ESFAS functions. For the SI and MSLI functions, three of the channels are used with a 2 out of 3 logic. For the CT function, four channels are employed with a 2 out of 4 logic.
The additional redundancy is added for system reliability due to the CT function being an "energize to trip" function.
During the 53 hours6.134259e-4 days <br />0.0147 hours <br />8.763227e-5 weeks <br />2.01665e-5 months <br />, 12 minutes that channel 2-P-0935 was inoperable, no event occurred that required the SI or MSLI actuations on high containment pressure. Had the SI and MSLI actuations been necessary, it is highly likely that the 2 out of 2 logic would have been satisfied. Even though the trip function is not single failure proof in this configuration, these channels are highly reliable with little history of failure. In addition, the SI or MSLI actuations could have been initiated from other diverse indications, such as low pressurizer pressure or low compensated steam line pressure.
If a parameter is used only for input to the protection circuits, three channels with a 2 out of 3 logic are sufficient to provide the required reliability and redundancy. If one channel fails in a direction that would not result in a partial function trip, the function is still operable with a 2 out of 2 logic. Therefore, the CT function would still have been satisfied with a 2 out of 3 logic, including the potential for a single failure of one channel.
As discussed above, no event requiring a SI, MSLI, or CT actuation actually occurred.
The SI and MSLI functions are backed up by other diverse indications that would have initiated equivalent mitigative functions. Finally, it is highly likely that any required SL MSLI, and CT actuations would still have occurred, even with the inoperable channel.
Therefore, no safety system functional failures occurred.
Enclosure to TXX-03197US. NUCLEAR EEGUlATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
Facility N (I)
Docker LER Number (6)
Pe3)
Year Sequential Revision COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 Number W
Number 05000446 03 004 00 5OF5 NARRAInVE (If 1m espae ia requred, we additnal copies ofNRC Fonn 366A) (17)
Based on this analysis, it was concluded that this event did not adversely affect the safe operation of CPSES Unit 2 or the health and safety of the public.
IV. CAUSE OF THE EVENT
TXU Energy believes that this event was caused by a random electronic failure in a power supply circuit card for an ESFAS intermediate range containment pressure channel. Once per shift, the maximum deviation between operable intermediate range containment pressure channels is verified to be < 3.0 psig. However, this verification was performed four times without the failed channel being discovered. This was due to the design of the indicating gauge on the Main Control Board not providing a large amount of resolution in the negative pressure region. This lack of resolution contributed to the failure to detect that the failed channel was reading approximately 0.7 psig low.
V.
CORRECTIVE ACTIONS
The failed power supply circuit card was replaced. As a part of the CPSES Corrective Action Program, Engineering will add a computer alarm for channel deviation between the four intermediate range pressure loops. This alarm will allow Operators to more easily identify this type of channel failure.
VL PREVIOUS SIMILAR EVENTS There have been no previous similar events in the last three years.