05000445/LER-2016-002, Regarding Unanalyzed Condition Involving Potential Moderate Energy Line Break
| ML16330A499 | |
| Person / Time | |
|---|---|
| Site: | Comanche Peak  |
| Issue date: | 11/10/2016 |
| From: | Dreyfuss J Luminant Power, TEX Operations Company |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TXX-16132 LER 16-002-00 | |
| Download: ML16330A499 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(viii)(B) 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 4452016002R00 - NRC Website | |
text
II Luminant CP-201601064 TXX-16132 November 10, 2016 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 John R. Dreyfuss Plant Manager John.Dreyfuss@luminant.com Ref:
SUBJECT:
COMANCHE PEAK NUCLEAR POWER PLANT DOCKET NOS. 50-445 AND 50-446 Luminant Power P 0 Box 1002 6322 North FM 56 Glen Rose, TX 76043 T 254 897 5200 c 802 380 0894 F 2548970410 10 CFR 50.73 UNANALYZED CONDITION INVOLVING POTENTIAL MODERATE ENERGY LINE BREAK LICENSEE EVENT REPORT 445/16-002-00
Dear Sir or Madam:
Pursuant to 10CFR50.73(a)(2)(ii)(B), TEX Operations Company LLC (TEX OpCo) hereby submits enclosed Licensee Event Report (LER) 445/16-002-00, "Unanalyzed Condition Involving Potential Moderate Energy Line Break,." for Comanche Peak Nuclear Power Plant (CPNPP) Units 1 and
- 2.
This communication contains the following new licensing basis commitments regarding CPNPP Units 1 and2.
Commitment No.
5355685 Commitment No.
5356321
Description
The systems interaction program maintenance procedure will be revised to provide additional guidance regarding MELB interactions and MELB shielding installation controls.
Description
A 100 percent walk down will be performed of rooms containing MELB piping identified for shielding to ensure all potential threats are properly shielded.
The commitment number is used by TEX OpCo for the internal tracking of CPNPP commitments.
Should you have any questions, please contact Mr. Gary Merka at (254) 897-6613.
U.S. Nuclear Regulatory Commission TXX-16132 Page 2 of 2 11 /10/2016 Enclosure c - Kriss Kennedy, Region IV Margaret M. Watford, NRR Resident Inspectors, Comanche Peak Sincerely, yLLC
NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (06-2016)
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 />.
+~r..,J>Alt£cll<-t.. o Reported lessons learned are incorporated into the licensing process and fed back to industry.
~
LICENSEE EVENT REPORT (LER)
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections
~
Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail I
(See Page 2 for required number of digits/characters for each block) to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a (See NUREG-1022, R.3 for instruction and guidance for completing this form means used to impose an information collection does not display a currently valid OMS control httg://www.nrc.gov/reading-rm/doc-collections/nuregs/staff[sr1022/r3/)
number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Comanche Peak Nuclear Power Plant 05000 445 I
OF 5
- 4. TITLE Unanalyzed Condition Involving Potential Moderate Energy Line Break
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I
SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR CPNPPUnit2 05000 446 FACILITY NAME DOCKET NUMBER 09 13 16 16 -
002 -
00 11 10 16 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 1 D 20.2201(d)
D 20.2203(a)(3)(ii)
[{) 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(1)
D 20.2203(a)(4)
D so.13(a)(2)(iii)
[{] 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. POWER LEVEL D 20.2203(a)(2)(ii)
D 50.36(c)(1)(ii)(A)
[{] 50.73(a)(2)(v)(A)
D 13.11(a)(4)
D 20.2203(a)(2)(iii)
D so.3a(c)(2)
D 50.73(a)(2)(v)(B)
D 13.11(a)(5)
D 20.2203(a)(2)(iv)
D so.4a(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 13.11(a)(1) 100 D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
[{] 50.73(a)(2)(v)(D)
D 13.11(a)(2)(i)
D 20.2203(a)(2)(vi)
[{) 50.73(a)(2)(i)(B)
[{] 50.73(a)(2)(vii)
D 13.77(a)(2)(ii)
D 50.73(a)(2)(i)(C)
D OTHER Specify in Abstract below or in SUMMARY. OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES:
At 1730 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.58265e-4 months <br /> on September 13, 2016, during a plant walk down with the NRG Senior Resident inspector, a vertical section of pressurized fire protection pipe [EllS:(IC}(PSP)] in the Service Water Intake Structure (SWIS} was found to not be shielded against a Moderate Energy Line Break (MELB). In the event of a MELB crack along any portion of the unshielded portion of pipe, the MELB had a potential impact to the function of any one of the 4 Service Water (SW) pumps, but only one train would have been affected during the event. This is due to physical configuration/separation relative to the source line and target pumps and/or associated Motor Control Centers (MCCs) that support pump operation. Upon discovery of this condition, SW Train B and Emergency Diesel Generator (EOG) Train B on each Unit was declared inoperable per Technical Specifications (TS}. NRG Event Report 52239 reported this as an unanalyzed condition per 10CFR50.72(b}(3)(ii)(B). At the time of discovery, all four Service Water trains were operable, therefore, this condition was not reportable as a loss of safety function per 10 CFR 50. 72(b )(3)(v).
At 2233 hours0.0258 days <br />0.62 hours <br />0.00369 weeks <br />8.496565e-4 months <br /> on September 13, 2016, the affected fire protection pipe was isolated and SW Train B and EDG Train B on each Unit were declared operable. On September 14, 2016, the NRG Senior Resident Inspector identified an additional section of fire protection piping that was not adequately shielded for a MELB. On September 16, 2016, the required MELB shielding was installed on affected fire protection piping in the SWIS. Since the SW trains have been periodically declared inoperable at various times in the last three years for surveillance testing or maintenance, given the MELB condition, two SW trains could have been inoperable and this is reportable per 10CFR50.73(a)(2)(i)(B), 10CFR50.73(a)(2)(ii)(B),
10CFR50.73(a)(2)(v), 1 OCFR50.73(a)(2)(vii), and 1 OCFR50.73(a)(2)(ix)(A).
At 1410 hours0.0163 days <br />0.392 hours <br />0.00233 weeks <br />5.36505e-4 months <br /> on October 6, 2016, during extent of condition walk downs, a section of eyewash station pipe [EllS:(KC)
(PSP)] in the Unit 2 Safeguards (SG) Building was identified that was not adequately shielded for a MELB. In the event of a MELB crack along any portion of this unshielded pipe, the MELB had the potential to impact Unit 2 Train B 480V MCC 2EB2-1.
This MCC provides power to Unit 2 Train B Emergency Core Cooling, Battery Charger, Containment Spray, and Containment Isolation Valve equipment. The affected eyewash station pipe was isolated shortly after it was discovered to not be adequately shielded for a MELB.
NRC Event 52239 was updated to report this as an unanalyzed condition per 10CFR50.72(b)(3)(ii)(B). At the time of discovery, 2EB1-1 and the Unit 2 Train A Emergency Core Cooling, Battery Charger, Containment Spray, and Containment Isolation Valve equipment were operable, therefore, this condition was not reportable as a loss of safety function per 10 CFR 50. 72(b )(3)(v).
Since 480V MCC 2EB1-1 and the Unit 2 Train A Emergency Core Cooling, Battery Charger, Containment Spray, and Containment Isolation Valve equipment trains have been periodically declared inoperable at various times in the last three years for surveillance testing or maintenance, given the MELB condition, 2EB1-1, 2EB2-1 and both trains of the Unit 2 Emergency Core Cooling, Battery Charger, Containment Spray, and Containment Isolation Valve equipment could have been inoperable and this is reportable per 10CFR50.73(a)(2)(i)(B), 10CFR50.73(a)(2)(ii)(B), 10CFR50.73(a)(2)(v),
10CFR50.73(a)(2)(vii), and 10CFR50.73(a)(2)(ix)(A).
At 1708 hours0.0198 days <br />0.474 hours <br />0.00282 weeks <br />6.49894e-4 months <br /> on October 10, 2016, as a result of ongoing extent of condition walk downs, a section of fire protection pipe [EllS:(IC)(PSP)] in the Unit 1 SG Building was identified that was not adequately shielded for a MELB. In the event of a MELB crack along any portion of this unshielded pipe, the MELB had the potential to impact Unit 1 Train B Switchgear 1 EA2, Unit 1 Train B 480V MCC 1 EB4-2, and Unit 1 Train B Distribution Panel 1 ED2-2. Only one of these power supplies at a time would have been affected. 1 EA2 provides 6.9KV electrical power to various Unit 1 Train B safety-related pumps, panels, sequencer, and transformers. 1 EB4-2 provides 480V electrical power to various Unit 1 Train B safety-related pumps, valves, fans, panels, and transformers. 1 ED2-2 provides 125VDC electrical power to the EOG 1-02 channel 1 starting circuit. The affected fire protection pipe was isolated shortly after it was discovered to not be adequately shielded for a MELB. NRC Event 52239 was updated to report this as an unanalyzed condition per 10CFR50.72(b)(3)(ii)
(B). At the time of discovery, none of the affected Train A equipment was inoperable. Therefore, this condition was not reportable as a loss of safety function per 10 CFR 50.72(b)(3)(v).
Since Unit 1 Train A Switchgear 1EA1, Unit 1 Train A 480V MCC 1 EB3-2, and Unit 1 Train A Distribution Panel 1 ED1-2 have been periodically declared inoperable at various times in the last three years for surveillance testing or maintenance, given the MELB condition, both trains of Unit 1 6.9KV power (1 EA2 and 1EA1 ), both trains of Unit 1 480V power (1 EB4-2 and 1 EB3-2), and both trains of Unit 1 125VDC power (1 ED2-2 and 1 ED1-2) along with the safety-related equipment they supply could potentially have been inoperable and this is reportable per 10CFR50.73(a)(2)(i)(B), 10CFR50.73(a)(2)(ii)(B),
10CFR50.73(a)(2)(v), 10CFR50.73(a)(2)(vii), and 1 OCFR50.73(a)(2)(ix)(A).
E. THE METHOD OF DISCOVERY OF EACH COMPONENT OR SYSTEM FAILURE, OR PROCEDURAL PERSONNEL ERROR The unanalyzed condition on September 13, 2016, was discovered during a plant walk down by Engineering (Utility, Non Licensed) personnel with the NRC Senior Resident inspector. The unanalyzed condition on September 14, 2016, was discovered during a plant walk down by the NRC Senior Resident inspector. The unanalyzed conditions on October 6, 2016, and October 10, 2016, were discovered during extent of condition walk downs by Engineering (Utility, Non Licensed) personnel.
II. COMPONENT OR SYSTEM FAILURES A. CAUSE OF EACH COMPONENT OR SYSTEM FAILURE Not applicable -
No component or system failures were identified during this event.
B. FAILURE MODE, MECHANISM, AND EFFECTS OF EACH FAILED COMPONENT Not applicable -
No component or system failures were identified during this event.
C. SYSTEMS OR SECONDARY FUNCTIONS THAT WERE AFFECTED BY FAILURE OF COMPONENTS WITH MULTIPLE FUNCTIONS Not applicable -
No component or system failures were identified during this event.
D. FAILED COMPONENT INFORMATION
Not applicable -
No component or system failures were identified during this event.
Ill. ANALYSIS OF THE EVENT A. SAFETY SYSTEM RESPONSES THAT OCCURRED Not applicable -No safety system responses occurred as a result Of this event.
B. DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY Due to a postulated MELB, the following equipment could have been inoperable since initial licensing (April 17, 1990 for Unit 1 and April 6, 1993 for Unit 2): Unit 1 SW Train B, Unit 2 SW Train B, Unit 1 EOG Train B, Unit 2 EOG Train B, Unit 2 Train B 480V MCC 2EB2-1, Unit 1 *Train B 6.9KV Switchgear 1 EA2, Unit 1 Train B 480V MCC 1 EB4-2, and Unit 1 Train B 125VDC Distribution Panel 1ED2-2.
C. SAFETY CONSEQUENCES AND IMPLICATIONS OF THE EVENT This event involved past inoperability of the following equipment: Unit 1 SW Train B, Unit 2 SW Train B, Unit 1 EOG Train B, Unit 2 EOG Train B, Unit 2 Train B 480V MCC 2EB2-1, Unit 1 Train B 6.9KV Switchgear 1 EA2, Unit 1 Train B 480V MCC 1 EB4-2, and Unit 1 Train B 125VDC Distribution Panel 1 ED2-2. Since the opposite trains of this equipment were periodically declared inoperable at various times in the last three years for surveillance testing or maintenance, given the MELB condition, both Trains of these systems would have been inoperable.
There were no actual safety consequences for this event. This is a postulated event and the risk associated with this issue was very low and the safety of the environment or general population was not threatened. This event has been evaluated to meet the definition of a safety system functional failure per 10CFR50.73(a)(2)(v).
IV. CAUSE OF THE EVENT
The most likely cause of this event was the methodology used to conduct the initial MELB walk downs was flawed and allowed some MELB threats to be missed. Given the demarcation of responsibility between the walk down teams and the Design Engineers, the most likely cause for failing to identify those potential threats was the method by which the MELB walk downs were conducted. The decision to conduct the walk downs by looking for threats from the target's point of view instead of looking from both the target's and*the threat's points of view resulted in valid threats going unrecognized.
Threats not recognized by the walk d.own teams would not have been made known to the Design Engineer preparing the associated design change documents and consequently the affected piping was not identified for shielding.
V. CORRECTIVE ACTIONS
The affected piping in the SWIS was shielded. The affected piping in the Unit 1 SG Building and Unit 2 SG Building will be shielded in accordance with the Corrective Action Program. A 100 percent walk down will be performed of rooms containing MELB piping identified for shielding to ensure all potential threats are properly shielded. The systems interaction program maintenance procedure will be revised to provide additional guidance regarding MELB interactions and MELB shielding installation controls.
If additional reportable events are identified during completion of the ongoing extent of condition walk downs, a supplemental report will be submitted.
VI. PREVIOUS SIMILAR EVENTS
There have been no previous similar reportable events at CPNPP in the last three years. Page 5
of 5