05000498/LER-2012-001, Regarding Instrumentation Channel NI-45A Failed Channel Check
| ML12178A064 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/31/2012 |
| From: | Gerry Powell South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| G25, NOC-AE-12002857, STI: 33550063 LER 12-001-00 | |
| Download: ML12178A064 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(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 |
| 4982012001R00 - NRC Website | |
text
Nuclear Operating Company South Texas Pro/ect Electric Generating Station PO. Bat 289 Wadsworth, Texas 77483 May 31, 2012 NOC-AE-12002857 File No.: G25 10 CFR 50.73 STI: 33550063 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738 South Texas Project Unit 1 Docket No. STN 50-498 Licensee Event Report 1-2012-001 Nuclear Instrumentation Channel NI-45A Failed Channel Check Pursuant to 10 CFR 50.73, STP Nuclear Operating Company (STPNOC) submits the attached Unit 1 Licensee Event Report (LER) 1-2012-001 to address the inoperability of Extended Range (E/R) Flux Lower Range Nuclear Instrument (NI-45A) based on failure to meet procedural acceptance criteria and Technical Specifications Limiting Condition of Operation.
This event is considered reportable pursuant to 10 CFR 50.73(a)(2)(i)(B), as any operation or condition that was prohibited by the plant's Technical Specifications.
This event did not have an adverse effect on the health and safety of the public.
This is this initial LER submittal. A planned supplement will be submitted no later than August 1,2012.
There are no commitments contained in this LER. Corrective actions will be implemented in accordance with the STP Corrective Action Program.
If there are any questions on this submittal, please contact either Joe Loya at (361) 972-8005 or me at (361) 972-7566.
G. T. Powell Vice-President, Generation JAL Attachment: LER 1-2012-001
NOC-AE-12002857 Page 2 of 2 cc:
(paper copy)
(electronic copy)
Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 1600 East Lamar Blvd Arlington, Texas 76011-4511 Balwant K. Singal Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (MS 8B1) 11555 Rockville Pike Rockville, MD 20852 Senior Resident Inspector U. S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP Peter Nemeth Crain Caton & James, P.C.
John Ragan Chris O'Hara Jim von Suskil NRG South Texas LP Kevin Polio Richard Pena City Public Service C. Mele City of Austin Richard A. Ratliff Texas Department of State Health Services Alice Rogers Texas Department of State Health Services Balwant K. Singal U. S. Nuclear Regulatory Commission
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO, 3150.0104 EXPIRES: 10/3112013 (10-2010)
Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />. Reported lessons learned are incorporated into the licensing process and fed back to industry. Send comments regarding burden estimate to the FOIA/PrIvacy Section (T-5 F53). U.S. Nuclear Regulatory Commission. Washington. DC 20555-0001, or by internet e-mail to LICENSEE EVENT REPORT(LR_______
LICE SEEEVE TR POR'n,',(:,IIo-....',
. y*,*', and to the Desk Officer, Office of Information and Regulatory Affairs. NEOB-10202. (3150-1104), Office of Management and (See reverse for reuired, number of Budget. Washington. DC 20503. If a means used to impose an information collection does not display a currently valid OMB.control number, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to the information collection.
- 3. PAGE South Texas Unit 1 05000498 1 OF 3
- 4. TITLE Unit 1 Nuclear Instrumentation Channel NI-45A Failed Channel Check
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTHI DAY I YEAR YEAR j SEQUENTIAL REV MONTH DAY iYEAR FACILITY NAME DOCKET NUMBER NUMBER NO.
I IN/A N/A 03 127 i2012 2012 001 0
05 31 2012 N/A N/A
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10CFR§: (Check all that apply)
U 20.2201(b)
U 20.2203(a)(3)(i)
EU 50.73(a)(2)(i)(C)
[: 50.73(a)(2)(vii)
U 20.2201(d)
U 20.2203(a)(3)(ii)
U 50.73(a)(2)(ii)(A)
U 50.73(a)(2)(viii)(A) 20.2203(a)(1)
El 20.2203(a)(4)
U 50.73(a)(2)(ii)(B)
U 50.73(a)(2)(viii)(B)
- 10. POWER LEVEL U 20.2203(a)(2)(i)
[U 50.36(c)(1)(i)(A)
[I 50.73(a)(2)(iii)
Ul 50.73(a)(2)(ix)(A) 100%
U 20.2203(a)(2)(ii)
[U 50.36(c)(1)(ii)(A)
EU 50.73(a)(2)(iv)(A)
U7 50.73(a)(2)(x)
U 20.2203(a)(2)(iii)
E] 50.36(c)(2)
U 50.73(a)(2)(v)(A)
U 73.71(a)(4)
U 20.2203(a)(2)(iv)
EU 50.46(a)(3)(ii)
U 50.73(a)(2)(v)(B)
U 73.71(a)(5)
EU 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
U 50.73(a)(2)(v)(C)
U OTHER U 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
Ul 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Joe Loya, Licensing Engineer 361-972-8005[v YES (if yes, complete 15. EXPECTED SUBMISSION DATE)
ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On March 27, 2012, Operations declared the Extended Range (E/R) Flux Lower Range Nuclear Instrument (Nl-45A) inoperable based on failure to meet channel check acceptance criteria per the "Remote Shutdown Monitoring AND Accident Monitoring Instrumentation Channel Checks" Procedure. Subsequent troubleshooting discovered an issue with the channel's isolation circuit card, ATI. The ATI card was found with a degraded condition which affected the output range of NI-45A. With this degraded condition, Extended Range (E/R) Flux Lower Range Nuclear Instrument (NI-45A) would not have been able to perform its design function. Subsequent review determined that NI 45A had been inoperable since February 29, 2012.
After replacement of the AT1 card, the surveillance procedure was completed satisfactory on March 30, 2012 and the instrument was restored to operable. Since NI-45 had been inoperable for longer than the applicable Technical Specification *7 day Allowed Outage Time, this event is reportable under 1 OCFR50.73(a)(2)(i)(B), as an Operation or Condition Prohibited by Technical Specifications.
This is the initial LER for this event. A planned Supplemental LER will be submitted as indicated above.
There were no personnel injuries, no offsite radiological releases, and no damage to safety-related equipment associated with this condition. This condition did not have an adverse effect on the health and safety of the public.
NRC FORM 366 (10-2010)
SUMMARY OF THE EVENT On March 27, 2012, Operations declared the Extended Range (E/R) Flux Lower Range Nuclear Instrument,(NI-45A) inoperable based on the failure to meet Technical Specifications (TS) channel check acceptance criteria per the "Remote Shutdown Monitoring AND Accident Monitoring Instrumentation Channel Checks" Procedure. Subsequent troubleshooting discovered an issue with the channel's isolation circuit card, AT1. The AT1 card was found with a degraded condition which affected the indication of NI-45A Lower Range. With this degraded condition, Extended Range (E/R) Flux Lower Range Nuclear Instrument (NI-45A) would not have been able to perform its design function. After replacement of the AT1 card, the surveillance procedure was completed satisfactory on March 30, 2012 and the instrument was returned to an operable condition.
Each E/R channel has a Lower Range (which provides indication in shutdown conditions (counts per second)) and an Upper Range (which provides indication at power). For the time period under evaluation, Unit 1 was operating at power and the E/R Lower Range indication was saturated and considered unreliable. The E/R Lower Range indication is considered unreliable above approximately 1E-4% Power (100,000 CPS). At 100,000 CPS, saturation occurs in the Extended Range Lower Range Nuclear Instrumentation circuitry and a channel may indicate less than 100,000 CPS.
A review of channel data indicated that starting in December 2011; the NI-45 E/R Lower Range indication began a downward trend. Subsequent Channel Checks performed in January and February (monthly surveillance) were completed satisfactorily. These Channel Checks are performed with an acceptance criterion that notes the Lower Range indications may be unreliable, and that other indications such as E/R Upper Range output may be used to determine problems with the detector. During this time period, there were no issues found with the detectors E/R Upperý Range output indication.
As Stated previously, a degraded condition (downward trend) involving the E/R Lower Range indication had been evident since December 2011. Even though this indication is considered unreliable, there is reasonable confidence that in this instance, the indication showed the degrading performance of the AT1 card. Based on how the Surveillance procedure is performed, the Channel Check between NI-45A and NI-46A would have failed to meet the "factor of 10" acceptance criteria on February 29, 2012, (NI-045A = 10,527 cps, NI-046A = 106,057 cps). Therefore, it was concluded that the E/R Lower Range indication was inoperable from February 29, 2012 until the FORM 366 (10-2010)LICENSEE EVENT REPORT (LER)
U.S. NUCLEAR REGULATORY COMMISSION CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL REV. NO I NUMBER 3 OF 3 South Texas Unit 1 05000498 NUMBER
.3.OF.3 2012 001 00 channel was restored to operable on March 30, 2012.
The TS 3.3.3.6 Allowed Outage Time for an inoperable Extended Range nuclear instrumentation channel is 7 days. Because Extended Range channel NI-45 was inoperable longer than the TS allowed outage time and associated shutdown time, this event is considered REPORTABLE under 1 OCFR50.73(a)(2)(i)(B), Operations or Conditions Prohibited by Technical Specifications.
E.
METHOD OF DISCOVERY
This event was discovered by Operations during the performance of the "Remote Shutdown Monitoring AND Accident Monitoring Instrumentation Channel Checks" surveillance procedure.
I1. EVENT-DRIVEN INFORMATION A.
SAFETY SYSTEMS THAT RESPONDED N/A B.
DURATION OF SAFETY SYSTEM INOPERABILITY
As discussed above, the Extended Range (E/R) Flux Lower Range Nuclear Instrument (NI-45A) was inoperable from February 29, 2012 until March 30, 2012 (approximately 31 days).
C.
SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT Nuclear or radiological safety was not affected. This event had no impact to the safety of the public or station personnel. This event did not impact the reliability of plant operation or production capacity. There was no impact to the Core Damage Frequency or Large Early Release Frequency associated with this event.
III. CAUSE OF THE EVENT
The Root Cause is under investigation and will be submitted in the planned LER supplement.
IV. CORRECTIVE ACTIONS
The Root Cause of the event, including the resulting corrective actions, is under investigation and will be submitted in the planned LER supplement.
V. PREVIOUS SIMILAR EVENTS
There have been no similar reportable events at STP within the last three years.
VI. ADDITIONAL INFORMATION
N/A FORM 366 (10-2010)