05000324/LER-2013-004, Regarding Operation Prohibited by Technical Specifications - Recirculation Loop Flow Mismatch
| ML13248A454 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 08/19/2013 |
| From: | Hamrick G Duke Energy Carolinas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BSEP 13-0093 LER 13-004-00 | |
| Download: ML13248A454 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3242013004R00 - NRC Website | |
text
0 ~DUKE ENERGY.
George T. Hamrick Vice President Brunswick Nuclear Plant P.O. Box 10429 Southport, NC 28461 o: 910.457.3698 AUG 19 2013 10 CFR 50.73 Serial: BSEP 13-0093 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
Subject:
Brunswick Steam Electric Plant, Unit No. 2 Renewed Facility Operating License No. DPR-62 Docket No. 50-324 Licensee Event Report 2-2013-004 In accordance with the Code of Federal Regulations, Title 10, Part 50.73, Duke Energy Progress, Inc., formerly known as Carolina Power & Light Company (CP&L), submits the enclosed Licensee Event Report (LER). This report fulfills the requirement for a written report within sixty (60) days of a reportable occurrence.
Please refer any questions regarding this submittal to Mr. Lee Grzeck, Manager - Regulatory Affairs, at (910) 457-2487.
Sincerely, George. Hamrick MAT/mat
Enclosure:
Licensee Event Report
U.S. Nuclear Regulatory Commission Page 2 of 2 cc (with enclosure):
U. S. Nuclear Regulatory Commission, Region II ATTN: Mr. Victor M. McCree, Regional Administrator 245 Peachtree Center Ave, NE, Suite 1200 Atlanta, GA 30303-1257 U. S. Nuclear Regulatory Commission ATTN: Ms. Michelle P. Catts, NRC Senior Resident Inspector 8470 River Road Southport, NC 28461-8869 U. S. Nuclear Regulatory Commission ATTN: Mr. Christopher Gratton (Mail Stop OWFN 8G9A) 11555 Rockville Pike Rockville, MD 20852-2738 Chair - North Carolina Utilities Commission P.O. Box 29510 Raleigh, NC 27626-0510
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Brunswick Steam Electric Plant (BSEP), Unit 2 05000324 1 of 4
- 4. TITLE Operation Prohibited by Technical Specifications - Recirculation Loop Flow Mismatch
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I ' FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR NUMBER NO.
jjFACILITY NAMIE DOCKET NUMBER 06 20 2013 2013-004-00 08 19 2013
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[E 50.73(a)(2)(vii) 1 El 20.2201(d)
El 20.2203(a)(3)(ii)
[] 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
[E 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
[I 20.2203(a)(2)(i)
[E 50.36(c)(1)(i)(A)
[I 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL El 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
[E 50.73(a)(2)(iv)(A)
[E 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4) 100 El 20.2203(a)(2)(iv)
[] 50.46(a)(3)(ii)
El 50.73(a)(2)(v)(B)
El 73.71 (a)(5)
El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
El OTHER El 20.2203(a)(2)(vi)
[
50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or I
in loop flows did not agree with RTGB indications. Loop flows were adjusted so that both were within the TS mismatch criteria. On December 28, 2010, procedure 0PT-50.5, Total Core Flow Calibration, was performed to match RTGB loop flow indicators to PPC. To determine the impact of the failed "P" converter and establish the extent of condition, Engineering personnel reviewed historical PPC data for both Unit 1 and Unit 2. On June 20, 2013, this review identified that Unit 2 operated with flow mismatch in excess of SR 3.4.1.1 requirements on four occasions (i.e., October 10, 2009, November 23, 2010, December 3, 2010, and December 18, 2010). Operation in this condition exceeded the Completion Times associated with TS 3.4.1 only twice (i.e., on December 3, 2010, and December 18, 2010).
Event Cause
The root cause of this event is lack of rigor in selecting instrumentation to satisfy SR 3.4.1.1.
BSEP converted to the Improved Technical Specifications (ITS) via Amendments 203 and 233 for Units 1 and 2, respectively, issued June 5, 1998. At conversion, SR 3.4.1.1 verified that recirculation pump speeds were within required limits as a means to monitor recirculation loop flow. Subsequently, it was determined that this method of confirming mismatch was not adequate (i.e., as documented in LER 1-2006-006, dated December 22, 2006, ADAMS Accession Number ML070040032), and SR 3.4.1.1 was revised to verify recirculation loop flows, versus recirculation pump speeds, were within mismatch requirements (i.e., via Amendments 244 and 272 for Units 1 and 2, respectively, issued December 17, 2007, ADAMS Accession Number ML073400247). To support implementation of these amendments, the RTGB recirculation loop flow indicators (i.e., from analog indication-only instrumentation B21-FI-R61 IA/B) were selected to perform SR 3.4.1.1. There is no documentation that either the instrument loop accuracy of RTGB recirculation loop flow indicators or the availability of more accurate indications from PPC points WJPAIB was considered. As a result, SR 3.4.1.1 has been completed using instrumentation which allowed the TS requirements to be unknowingly exceeded.
Safety Assessment
The safety significance of this event is minimal. Conservative evaluations performed by GE Nuclear Energy with the limiting Design Bases Accident Loss-of-Coolant Accident scenario show insignificant impact on resulting maximum peak clad temperature when operating with up to and including a 10 percent flow rate mismatch in the recirculation loops. Similarly the local oxidation and core-wide metal water reaction equivalent cladding reacted values do not result in noticeable change. These results bound the maximum recirculation loop flow mismatch observed on the event dates.
Corrective Actions
Any changes to the corrective actions and schedules noted below will be made in accordance with the site's corrective action program.
NRC FORM 366 (10-2010)
The following corrective actions have been completed and will ensure compliance with the Technical Specifications until the longer term actions planned to prevent recurrence can be implemented.
Procedures 101-03.1 and 201-03.2, Reactor Operator Daily Surveillance Report, for Units 1 and 2, respectively, were revised to require both PPC and RTGB loop flow conditions be maintained within SR 3.4.1.1 mismatch criteria. This will ensure that analog, indication-only instruments are not the sole source of indication for monitoring recirculation loop flows.
Procedures 101-03.1 and 201-03.2 were reviewed to ensure no other analog, indication-only instruments were used for Technical Specification compliance.
The following longer-term corrective actions to prevent recurrence are planned.
An evaluation will be performed to determine instrument loop accuracies associated with recirculation loop flow indicators B21-FI-R61 1A/B for Units 1 and 2 and PPC points CPWJPAIB.
These accuracies will be incorporated into the acceptance criteria for the SR 3.4.1.1 sections of procedures 101-03.1 and 201-03.2. These actions are currently planned to be completed by March 13, 2014.
Procedure OPT-50.5, Total Core Flow Calibration, will be revised to establish acceptance criteria for recirculation loop flow indications and establish a monthly performance frequency. Additionally, a caution statement, indicating that large adjustments to loop summer gains have the potential to mask upstream hardware equipment failures, will be added. These actions are currently planned to be completed by March 13, 2014.
Previous Similar Events
A review of LERs and corrective action program condition reports for the past three years identified no previous similar occurrences.
As discussed above, LER 1-2006-006, dated December 22, 2006, identified that verification of recirculation loop mismatch via recirculation pump speed versus flow was inappropriate. The root cause of this event reported in LER 2-2013-004 is associated with implementation of the corrective action from LER 1-2006-006 to revise SR 3.4.1.1 to monitor recirculation loop flow.
Commitments
No regulatory commitments are contained in this report.
NRC FORM 366 (10-2010)