05000353/LER-2007-003, Re Automatic Actuation of the Reactor Protection System at Power
| ML071730270 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/22/2007 |
| From: | Mudrick C Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 07-003-00 | |
| Download: ML071730270 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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 |
| 3532007003R00 - NRC Website | |
text
10CFR50.73 June 22, 2007 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 2 Facility Operating License No. NPF-85 NRC Docket No. 50-353 Subject: LER 2-07-003, Automatic Actuation Of The Reactor Protection System At Power This Licensee Event Report (LER) addresses an event that resulted in an automatic actuation of the reactor protection system due to a valid reactor low-level condition. This event was caused by an intermittent failure of a circuit card in the redundant reactivity control system that initiated a feedwater pump speed runback.
Report Number:
2-07-003 Revision:
00 Event Date:
April 24, 2007 Discovered Date:
April 24, 2007 Report Date:
June 22, 2007 This LER is being submitted pursuant to the requirements of 10CFR50.73(a)(2)(iv)(A), 10CFR50.73(a)(2)(v)(D) and 10CFR50.73(a)(2)(i)(B).
There are no commitments contained in this letter.
If you have any questions or require additional information, please do not hesitate to contact us.
Sincerely, Original signed by Edward Callan for Chris Mudrick Christopher H. Mudrick Vice President - Limerick Exelon Generation Company, LLC cc: S. J. Collins, Administrator Region I, USNRC S. L. Hansell, USNRC Senior Resident Inspector, LGS
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-2004)
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digits/characters for each block)
APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Limerick Generating Station, Unit 2
- 2. DOCKET NUMBER 05000353
- 3. PAGE 1 OF 5
- 4. TITLE Automatic Actuation of the Reactor Protection System at Power
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL NUMBER REV NO.
MONTH DAY YEAR FACILITY NAME DOCKET NUMBER 05000 04 24 2007 2007 - 003 - 0 06 22 2007 FACILITY NAME DOCKET NUMBER 05000
- 9. OPERATING MODE 1
- 10. POWER LEVEL 100
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 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)(1)(i)(A) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(2)(ii) 50.36(c)(1)(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2203(a)(2)(iii) 50.36(c)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(v) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(C)
OTHER 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in (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) condition existed on Unit 2 for approximately 8 years; Unit 1 was not affected. The as-left flow control settings are approximately the settings used on Unit 1, which were verified to be stable during HPCI and RCIC injections on April 20, 1999 and April 23, 2003.
Cause of the Event
The scram was caused by an intermittent failure of a circuit card in RRCS division 1B concurrent with ongoing testing on division 1A that caused a reactor feedwater runback.
The flow oscillations on HPCI and RCIC were caused by improper flow control loop setting adjustments of gain and reset.
Corrective Action Completed The degraded circuit card in RRCS division 1B was replaced.
The Unit 2 flow control loop gain and reset settings for HPCI and RCIC were set to be consistent with the Unit 1 settings.
The procedure for tuning of HPCI and RCIC flow controls was revised to specify the required gain and reset settings.
Previous Similar Occurrences There were no previous similar occurrences of scrams caused by feedwater runback. There were previous similar occurrences of scrams caused by a loss of feedwater. These events were reported in LERs 1-03-003, 1-99-003, and 2 015. There were no previous similar occurrences of flow oscillations during HPCI or RCIC injection.
Component data:
HPCI and RCIC Analog Flow Controllers Manufacturer: B045 ABB Automation Inc.
Model number: 701003AAAE1 RRCS High Power Output Isolator Circuit Card Manufacturer: G080 General Electric Part number:
219B5369G005