05000410/LER-2018-002, Turbine Trip and Scram Due to Unit Differential Relay Trip
| ML18306A486 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 10/25/2018 |
| From: | Kreider R Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NMP2L2672 LER 2018-002-00 | |
| Download: ML18306A486 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(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) |
| 4102018002R00 - NRC Website | |
text
...
Exelon Generation NMP2L2672 October 25, 2018 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 Docket No. 50-41 O 10 CFR 50.73
Subject:
NMP2 Licensee Event Report 2018-002, Turbine Trip and Scram Due to Unit Differential Relay Trip In accordance with the reporting requirements contained in 1 O CFR 50.73(a)(2)(iv)(A), please find enclosed NMP2 Licensee Event Report (LER) 2018-001, Turbine Trip and Scram Due to Unit Differential Relay Trip.
There are no regulatory commitments contained in this letter.
Should you have any questions regarding the information in this submittal, please contact Dennis M. Moore, Site Regulatory Assurance Manager, at (315) 349-5219.
?(?~<<10:
Robert E. Kreider Jr.
Plant Manager, Nine Mile Point Nuclear Station Exelon Generation Company, LLC REK/RSP
Enclosure:
NMP2 Licensee Event Report 2018-002, Turbine Trip and Scram Due to Unit Differential Relay Trip cc:
NRG Regional Administrator, Region I NRG Resident Inspector NRG Project Manager
____J
Enclosure NMP2 Licensee Event Report 2018-002, Turbine Trip and Scram Due to Unit Differential Relay Trip Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03/31/2020 (04-2018)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
3.Page Nine Mile Point Unit 2 05000410 1
OF 4
- 4. Title NMP2 Turbine Trip and Scram Due to Unit Differential Relay Trip
- 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 NA NA Facility Name Docket Number 08 27 2018 2018 - 002 00 NA NA
- 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 q0.73(a)(2)(viii)(A)
D 20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B) 1 D
D D
D 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1 )(i)(A)
~ 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)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71(a)(5)
D 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(C)
D 73.77(a)(1) 100%
D 20.2203(a)(2)(v)
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
D 50.73(a)(2)(i)(C)
D Other (Specify in Abstract below or in F. SAFETY SYSTEM RESPONSES:
- Following the reactor scram safety systems operated per design.
II.
CAUSE OF EVENT
The direct cause of this event is an actuation of the 'A' Phase Unit Differential Relay, 87-2SPUY02(1) due to a grid disturbance on the 'A' phase of the 2-15 Clay-Edie transmission line. The root cause of the event is a failure of the Relay & Control technicians to hold themselves accountable for use of the HU tools in preventing errors while removing grounding screws from the Unit Differential Relaying Circuitry. The screws were initially installed during the refuel outage to facilitate generator testing. The failure to remove all the -
screws after testing reduced the margin to actuation of the Unit Differential Relay Scheme making it vulnerable to the external fault outside of its zone of protection.
Ill.
ANALYSIS OF THE EVENT
This event is reportable in accordance with 1 OCFR.50.72(b)(2)(iv)(B) and 10CFR50.73(a)(2)(iv)(A). The event caused a valid actuation of the RPS system. The actuation was not part of a preplanned sequence during testing or reactor operation.
IV.
CORRECTIVE ACTIONS
A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT STATUS Operations responded in accordance with appropriate procedures and restored all impacted systems to pre-event status.
B. ACTION TAKEN TO PREVENT RECURRENCE Corrective actions included: removal of the identified shorting screws and qualifications for those involved with the event.
V.
ADDITIONAL INFORMATION
A. FAILED COMPONENTS There were no failed components that contributed to this event B. PREVIOUS LERS ON SIMILAR EVENT:
There are no previous LERs for similar events C. THE ENERGY INDUSTRY IDENTIFICATION SYSTEM '(EIIS) COMPONENT FUNCTION IDENTIFIER AND SYSTEM NAME OF EACH COMPONENT OR SYSTEM REFERRED TO IN THIS LER:
Comgonent IEEE 803 Function IEEE 805 S~stem Identifier Identification Turbine Control Valve ISV SB Turbine Bypass Valve PCV SB Digital Electro Hydraulic NA TG Control System Relav RLY FK Main Turbine TRB TA Reactor Protection N/A SC System D. SPECIAL COMMENTS:
None Page_4_ of _4_