05000446/LER-2003-005, Regarding Actuation of Reactor Protection System
| ML040610769 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 02/20/2004 |
| From: | Madden F TXU Electric |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| CPSES-200400191, TXX-04004 LER 03-005-00 | |
| Download: ML040610769 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(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)(v), Loss of Safety Function |
| 4462003005R00 - NRC Website | |
text
Ah TXU WATxU TXU Energy Comanche PeakSteam Electric Station P.O. Box 1002 (EO1)
Glen Rose,TX 76043 Tel: 254 897 5209 Fax: 254 897 6652 mike.blevins@txu.com Mike Blevins Senior Vice President & Principal Nuclear Officer Ref: 10CFR50.73(a)(2)(iv)(A)
CPSES-200400191 Log # TXX-04004 February 20, 2004 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
SUBJECT:
COMANCHE PEAK STEAM ELECTRIC STATION (CPSES)
DOCKET NO. 50-446 ACTUATION OF REACTOR PROTECTION SYSTEM LICENSEE EVENT REPORT 446/03-005-00 Gentlemen:
Enclosed is Licensee Event Report (LER) 03-005-00 for Comanche Peak Steam Electric Station Unit 2, "Stroboscope Assembly Falls Into Rectifier Wheel Causing a Reactor Trip."
This communication contains no new licensing basis commitments regarding CPSES Units 1 and 2.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway Comanche Peak Diablo Canyon Palo Verde
- South Texas Project Wolf Creek
TXX-04004 Page 2 of 2 Sincerely, TXU Generation Company LP By:
TXU Generation Management Company LLC, Its General Partner Mike Blevins By:-z& tfM 2 2Q
- red W. Madden Nuclear Licensing Manager GLM/gm Enclosures c -
B. S. Mallett, Region IV W. D. Johnson, Region IV M. C. Thadani, NRR Resident Inspectors, CPSES
Enclosure to TXX-04004 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 315001204 (7-2001)
EXPIRES 07312004
, the NRC rnay not conduct or sponsor, and a pesoan k not required to recrond to. the Information collection.
Facilty Name (t)
Docket Number (2)
Page t COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 1 OF S Title (4)
ACTUATION OF REACTOR PROTECTION SYSTEM Event Date (5)
LER Number (6)
Revort Date (7)
Other Facilities Involved (5)
Month Day Year Year Sequia Revision Month Day Year Facility Name Docket Numbers il Nurnber Et Nurnber N A05000 12 22 03 03 _
005 00 02 20 N
05000 Operatig nli repon hs stt pursuam to the nequ rtmems of 10 CFR: (Check all that apply) (I t)
Mitode (9) 1 20.2201 (b) 20.2203(a)(3Xi) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)
Peowe 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A)
Litnrl 99.5 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(2)(i)(A) 50.73(a)(2)(iii) 5.73(aX2)(ix)(A) 20.2203(a)(2)(ii) 50.36(c)(1)(iiXA)
X 50.73(aX2)(iv)(A) 50.72(a)(2)(x) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(aX2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B)_
73.71 (a)(5) 20.2203(a)(2)(v) 50.73(aU2)()(A) 50.73(a)(2(v)(C)
OTHER 20.2203(af)(vi) 50.73(a)2)(i)(B)
=
50.73(a)(2)(v)(D)
Specify in Abstract below or F-in =
(If mne spae is requre4 use a1dorma copes of SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES On December 22, 2003, Comanche Peak Steam Electric Station (CPSES) Unit 2 was in Mode 1 operating at 99.5 percent power. At 0827 hours0.00957 days <br />0.23 hours <br />0.00137 weeks <br />3.146735e-4 months <br />, a Meter and Relay Technician (utility, non-licensed) entered the Main Generator exciter house [EHS:
(TB)(IX)(ENCL)] to collect monthly voltage and current data readings from the operating 2-01 Main Generator rotor shaft. This activity requires a technician to use a hand-held probe for making contact with the Main Generator rotor shaft. The probe is constructed from a wooden dowel approximately four feet long with a metallic contact and meter leads affixed to one end. Following procedure instructions, the technician contacted the shaft with the probe and successfully acquired the voltage and current data.
Upon completing the task, the technician turned to exit the exciter house. As he turned he inadvertently struck the "A" stroboscope assembly with the probe. The "A" stroboscope is located on the rotating rectifier wheel [EIIS: (TB)(RECT)] air guide cover directly adjacent to the position from which the data is acquired. When the stroboscope assembly was struck, the lamp reflector separated from the stroboscope assembly, falling approximately eighteen inches and into the "A" (negative) rectifier wheel.
NRC FOR.M 366A (I-20I)
Enclosure to TXX-04004 (If mnre space Is required. use additional copies of (If ore space is required. use dit iotnal opies of NRC Form 36a) (17)
III.
ANALYSIS OF THE EVENT
A.
SAFETY SYSTEM RESPONSES THAT OCCURRED The Reactor Protection System and The Auxiliary Feedwater System actuated during the event. The Unit 2 reactor automatically tripped on a "Turbine Trip
>50% Power" signal, and all three Auxiliary Feedwater pumps automatically started on "Steam Generator Lo-Lo water level" signals.
B.
DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY Not applicable -- No safety system train was rendered inoperable.
C.
SAFETY CONSEQUENCES AND IMPLICATIONS
This event is specifically bounded by the Final Safety Analysis Report (FSAR) accident analysis of the turbine trip presented in Section 15.2.3 of the CPSES FSAR. The analysis uses conservative assumptions to demonstrate the capability of pressure relieving devices and to demonstrate core protection margins. The event of December 22, 2003, occurred at 99.5 percent reactor power, and all safety related systems and components functioned as designed. There were no safety system functional failures associated with this event.
Based on the above, it is concluded that the event of December 22, 2003, 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 the cause of the event was improper reassembly of the stroboscope. The stroboscope lamp reflector is mounted to the rotating rectifier wheel air guide cover using four cap screws and retaining clips. Inspection of the "A" stroboscope assembly after this event revealed that all of the cap screws and retaining clips for the lamp reflector were loose, and the retaining clips were not oriented in their normal/design position. The personnel who reassembled the stroboscope did not ensure that the retaining clips were sufficiently tight and oriented as required.
NRC FURM 36A (1-21)
Enclosure to TXX-04004 NRC FORAI 36A U.S. NUCLEAR REGULATORY COMMISSION (1.2001)
LICENSEE EVENT REPORT (LER)
Facilly Name (I)
Docket LER Number(6)
Page(3)
Year iSequential illReib COMANCHE PEAK STEAM ELECTRIC STATION UNIT 2 05000446 IN Numbs NI s
O F
5 0500044 [WT H 00 I5 50F5 NARRATIVE (if mme space is requrd. use addnional copies of NRC Form 366A) (17)
The work instructions for disassembly/reassembly of the stroboscope are generic and nondescript in nature. TXU Energy believes that this vagueness contributed to the personnel error which resulted in the stroboscope being reassembled incorrectly.
V.
CORRECTIVE ACTIONS
Access to the Unit 1 and Unit 2 Main Generator exciter houses and monthly collection of rotor voltage and current data on the Unit 1 and Unit 2 Main Generator were suspended.
The damaged components in the Unit 2 rectifier wheel were repaired/replaced and the "A" stroboscope assembly was reassembled correctly. The "B" stroboscope assembly was also found to be incorrectly assembled and it was subsequently assembled correctly. Both Unit 1 stroboscopes were inspected and found to be correctly assembled.
As a part of the CPSES corrective action program, the following actions will be taken to prevent recurrence:
- 1. The work instructions for disassembly and reassembly of stroboscopes will be enhanced.
- 2. Other turbine work instructions that may have a similar potential to cause a reactor trip will be reviewed, and enhancements will be implemented as appropriate.
- 3. To heighten awareness of this event, a Lessons Learned will be issued on this event to all personnel that are regularly involved in Main Generator work.
VI.
PREVIOUS SIMILAR EVENTS
There have been other events which resulted in a turbine trip followed by an automatic reactor trip. However, the causes of those events were sufficiently different such that the previous corrective actions could not have prevented this event.
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