05000313/LER-2005-003, Unit 1, Re Reactor Trip Due to Automatic Actuation of the Reactor Protection System on Main Turbine Trip and Invalid Actuation of the Emergency Feedwater System
| ML060670310 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 02/24/2006 |
| From: | James D Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 1CAN020601 LER 05-003-00 | |
| Download: ML060670310 (6) | |
| 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)(ix)(A) 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 |
| 3132005003R00 - NRC Website | |
text
En tergy Entergy Operations, Inc.
1448 S.R. 333 Russeliville, AR 72802 Tel 501 858 5000 1 CAN020601 February 24, 2006 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001
Subject:
Licensee Event Report 50-313/2005-003-00 Arkansas Nuclear One - Unit 1 Docket No. 50-313 License No. DPR-51
Dear Sir or Madam:
In accordance with 10CFR50.73(a)(2)(iv)(A), enclosed is the subject report concerning an automatic actuation of the Reactor Protection System and an invalid actuation of the Emergency Feedwater System.
This correspondence contains no commitments.
Sincerely, Dale E ames Man er, Licensing DEJ/fpv Enclosure
- ILIE91.
1 CAN020601 Page 2 of 2 cc:
Dr. Bruce S. Mallett Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339-5957 LEREvents@inpo.org
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007 (6-2004.
, the NRC may diqits/characters for each block)
.not conduct or sponsor, and a person Is not required to respond to, the diais/Chra~ers or ech lo~k information collection.
- 3. PAGE Arkansas Nuclear One - Unit 1 05000313 1 OF 4
- 4. TITLE Reactor Trip due to Automatic Actuation of the Reactor Protection System on Main Turbine Trip and Invalid Actuation of the Emergency Feedwater System
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MO NTH Y YEAR YEAR NEUMBER N O.
MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 12 26 2005 2005 - 003 -
00 02 24 2006 05000
- 9. OPERATING MODE 11 THIS REPORTIS SUBMITTED PURSUANTTOTHEREQUIREMENTS OF 10 CFR§: (Check althatapply) o 20.2201(b) 0 20.2203(a)(3)(i).,,
El 50.73(a)(2)(i)(C)
El 50.73(a)(2)(vii) 1 l 20.2201(d) 0 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) ol 20.2203(a)(1)
El 20.2203(a)(4)
El 50.73(a)(2)(ii)(B)
[I 50.73(a)(2)(viii)(B)
Eo 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
[I 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii) 0] 50.36(c)(1)(ii)(A)
Z 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x) 0 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) 0 73.71(a)(4) 95 l 20.2203(a)(2)(iv)
Ei 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B)
El 73.71(a)(5) 0l 20.2203(a)(2)(v)
[I 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
Li OTHER Ll 20.2203(a)(2)(vi)
El 50.73(;a)(2)(i)(B) 0 50.73(a)(2)(v)(D)
Specify In Abstract below
- 12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (incude Area Code)
Fred Van Buskirk, Nuclear Safety and Licensing Specialist 479-858-3155CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TOEPIX B
TD V
W120.
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YEAR SUBMISSION D YES (Ifyes, complete 15. EXPECTED SUBMISSION DATE) 3 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
At 1047 CST, on December 26, 2005, Arkansas Nuclear One, Unit 1 (ANO-1), experienced an automatic actuation of the Reactor Protection System due to a Main Turbine trip caused by low turbine bearing lube oil pressure. The Reactor Protection System performed as designed resulting in a reactor trip from 95 percent power. Analysis of the event has determined that the reduction in turbine bearing lube oil pressure was caused by a failure of the lube oil ejector discharge check valve, LO-79. Subsequent analysis established that a weld failure within the valve internals had caused the disc to separate from the hinge resulting in blockage of lube oil flow. Examination of the failed welds indicated that they were undersized for the applied load. To correct this condition, a replacement valve assembly, meeting original equipment manufacturer design requirements, was installed. Following the reactor trip, a spurious actuation of Emergency Feedwater (EFV) occurred which was caused by an invalid low steam generator level signal generated by the Emergency Feedwater Initiation and Control system. To reduce the likelihood of recurrence of an invalid EFW actuation, a Technical Specification amendment was prepared and implemented upon NRC approval, allowing a reduction of the EFW low steam generator level initiation setpoint and an increase in the low level actuation time delay.
NRC FORM 3656 (6-2004)
PRINTED ON RECYCLED PAPER
(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 NJRC Form 366A)
D. In the interim, while the Technical Specification change was undergoing NRC review and approval, reactor power was limited to approximately 98 percent in order to provide margin between the EFIC low steam generator indicated level and the Emergency Feedwater actuation setpoint.
E.
Safety Significance
The Reactor Protection System operated as designed to initiate the automatic reactor trip in response to the trip of the Main Turbine. Although there was an invalid actuation of Emergency Feedwater following the reactor trip, post-trip response was not significantly complicated by this occurrence, and the EFRV system actuated and functioned as designed in response to the spurious low steam generator level signal. The post-trip plant response was normal with stable Hot Standby conditions (Mode 3) promptly established. Therefore, this event had minimal safety significance.
F.
Basis for Reportability The automatic actuation of the Reactor Protection System is reported in accordance with I OCFR50.73(a)(2)(iv)(A). A report of this event was made to the NRC Operations Center at 1435 CST on December 26, 2005, in accordance with 10CFR50.72(b)(2)(iv)(B). The invalid actuation of Emergency Feedwater is reported in accordance with 10CFR50.73(a)(2)(iv)(A).
G.
Additional Information
There have been no previous similar events reported by ANO as Licensee Event Reports.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].