05000461/LER-2019-002, For Clinton Power Station, Unit 1, Turbine Driven Reactor Feed Pump Hydraulic Control Failure Results in Automatic Scram
| ML19277E367 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 10/01/2019 |
| From: | Stoner T Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-604508 LER 2019-002-00 | |
| Download: ML19277E367 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(x) 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)(ii)(8) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition |
| 4612019002R00 - NRC Website | |
text
Clinton Power Statton 8401 Power Road Clinton, IL 61727 U-604508 October 1, 2019 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461 Subject: Licensee Event Report 2019-002-00 Exelon Generation GD 10 CFR 50.73 SRRS 5A.108 Enclosed is Licensee Event Report (LER) 2019-002-00: Turbine Driven Reactor Feed Pump Hydraulic Control Failure Results in Automatic SCRAM. This report is being submitted in accordance with the requirements of 1 O CFR 50.73.
There are no regulatory commitments contained in this report.
Should you have any questions concerning this report, please contact Mr. Dale Shelton, Regulatory Assurance Manager, at (217) 937-2800.
Respectfully, Theodore R. Stoner Site Vice President Clinton Power Station
Attachment:
Licensee Event Report 2019-002-00 cc:
Regional Administrator - Region Ill NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety - Illinois Emergency Management Agency
NRC FORM366 (04-2018)
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- 1. Faclllty Name Clinton Power Station, Unit 1
- 2. Docket Number 05000461 3.Page 1
OF 4
- 4. Title Turbine Driven Reactor Feed Pump Hydraulic Control Failure Results in Automatic SCRAM
- 5. Event Date Month Day y...,.
Year
- 6. LEA Number S9QUeflbal Number Rw No
- 7. Report Date Month Day Year Facility Name Fnclllty Name
- 8. Other Facllltles Involved Docket Number 06000 08 03 2019 2019 002 00 10 01 2019 Docket Number 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(~)(3)(1)
D 50.73(a)(2)(n)(A)
D 50 73(a)(2)(vm)(A) 1 D 20 2201 (d)
D 20 22D3(a)(3)(n) l'8J 50 73(a)(2)(1Q(B)
D 50 73(a)(2)(vrn)(B)
D 20 2203(a)(1)
D 20 22D3(a)(4)
D 50 73(a)(2)(111)
D 50 73(a)(2)(1x)(A)
D 20 2203(a)(2)(1)
D 50 36(c)(1)(1)(A) l'8J 50 73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. Power Level D 20 2203(a)(2)(n)
D 50.36(c)(1)(n)(A)
D 50 73(a)(2)(v)(A)
D 73 71 caH4l D 20 2203(a)(2)(111)
D 50.36(c)(2)
D 50 73(a)(2)(v)(B)
D 73 71 ca)(5)
D 20 2203(a)(2)(iv)
D 50 46(a)(3)(u)
[8J 50 73(a)(2)(v)(C)
D 73 n(a)(1) 098 D 20 2203(a)(2)(v)
D 50 73(a)(2)(1)(A)
[8J 50 73(a)(2)(v)(D)
D n77(a)(2)(1)
D 20.2203(al,(2)(v1)
D so 73(a)(2)(1J(Bl D 50.73(a)(2)(vu)
D 73 77(a)(2)(n)
D 50 73(a)(2)(1)(C)
D Other (Specrfy In Abstract below or 1n NRG Fonn 366A)
- 12. Licensee Contact for this LER Licensee Contact Mr. Dale Shelton, Regulatory Assurance Manager Telephone Number (Include Area Code)
(217) 937-2800 Cause B
Component p
Menufactun,r Reportable to ICES GE y
- 14. Supplemental Report Expected D Yes (If yes, complete 15. Expected Subrrnss1on Date) ~ No System Component
- 15. Expected Submission Date Abstract (Umrt to 1400 spaces, 1 e., approximately 14 single-spaced typewrltten lines)
Manufacturer Reportable to ICES Month YBBr On August 3, 2019, at 0226 CDT, while operating at approximately 98% power, the Turbine Driven Reactor Feed Pump (TDRFP) 8 horizontal hardware connection to the Linear Variable Differential Transformer (LVDT) failed causing loss of feedback to the feedwater control system. Flow from TDRFP 8 decreased while TDRFP A flow increased and reactor level decreased to the scram setpoint, which caused an automatic Reactor Protection System (RPS) scram. All control rods fully inserted. The reactor water Leval 2 setpoint was reached and High Pressure Core Spray (HPCS), Reactor Core Isolation Cooling (RCIC), Division 3 diesel generator, Standby Gas Treatment Systems A and 8, and all safety related shutdown service water pumps started as expected. RCIC and HPCS injected as expected. All Leval 2 containment isolation valves closed as expected. As a result of automatic isolation of the containment ventilation system, the Primary Containment to Secondary Containment and the Drywell to Primary Containment differential pressure limits were exceeded. The cause of the event was the design of the horizontal connecting hardware to thaTDRFP 8 operating cylinder positron LVDT was not adequate to withstand cyclic loading. The failed LVDT was replaced on TDRFP 8, along with associated horizontal connecting hardware. A design change will be developed and installed to strengthen the connecting hardware to the TDRFP 8 operating-cylinder LVDT such that it is adequate to withstand cyclic loading. This event is reportable under 10 CFR 50.73(a)(2)(iv)(A), 10 CFR 50.73(a)(2)(v)(D), 10 CFR 50.73(a)(2)(ii)(8), and 10 CFR 50.73 a 2 v C.
NRG FORM 366 (04-2018)
PLANT AND SYSTEM IDENTIFICATION
General Electric -- Boiling Water Reactor, 3473 Megawatts Thermal Rated Core Power Energy Industry Identification System (EIIS) codes are identified in text as [XX].
EVENT IDENTIFICATION Turbine Driven Reactor Feed Pump Hydraulic Control Failure Results in Automatic SCRAM A.
Plant Operating Conditions Before the Event
Unit: 1 Mode: 1 Event Date: August 3, 2019 Mode Name: Power Operation B.
Description of Event
Event Time: 0226 Reactor Power: 098 00 On August 3, 2019, at 0226 CDT, while operating at approximately 98% power, the Turbine Driven Reactor Feed Pump [SJ-P] (TDRFP) B horizontal hardware connection to Linear Variable Differential Transformer (LVDD 1ZT-FW199 failed causing loss of LVDT feedback fo the feedwater control system for TDRFP 8.- Flow from TDRFP B began decreasing due to the control system reducing speed demand in response to the LVDT failure. TDRFP A [SJ-P] speed and flow increased to maximum and reactor water level decreased to the scram setpoint within 15 seconds, which caused an automatic Reactor Protection System (RPS) scram. Operators placed the reactor mode switch in shutdown and completed the scram response actions.
All control rods fully inserted. Due to the failure mode of TDRFP B (i.e., the pump slowed but did not trip), a trip 'of the feed pump was not sensed by the Reactor Recirculation [AD] (RR) flow control valve [FCV] runback circuitry. With TDRFP A injeding post scram, reactor water level continued to lower to below the Level 2 setpoint. When the reactor' water Level 2 setpoint was reached during the event, the High Pressure Core Spray (HPCS) system [BG], Reactor Core Isolation Cooling (RCIC) system [BN], Division 3 diesel generator [DG] (DG), Standby Gas Treatment Systems [BH] A and B, and all safety related shutdown service water pumps [81-P] started as expected. RCIC and HPCS injected as expected. All reactor water Level 2 containment isolation signals [JM] occurred as expected and all associated containment isolation valves [ISV] closed as expected.
Following automatic initiation of HPCS as described above, the system was manually secured using station procedures after verification that additional Reactor Pressure Vessel [RPV] (RPV) injection was no longer required. The Primary Containment to Secondary Containment and the Drywell to Primary Containment differential pressure Technical Specification (TS) limits were exceeded as a NRG FORM 386A (04-201 B)
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SEQUENTIAL NUMBER 002 REV NO.
00 result of the reactor water Level 2 containment isolation of the containment ventilation system. The Primary Containment to Secondary Containment and the Drywall to Primary Containment differential pressure were restored to within TS limits at 1505 hours0.0174 days <br />0.418 hours <br />0.00249 weeks <br />5.726525e-4 months <br /> on August 3, 2019, within the TS action time limits.
C.
Cause of the Event
The cause of this event was the design of the horizontal connecting hardware to the TDRFP B operating cylinder position LVDT was not adequate to withstand cyclic loading.
D.
Safety Consequences
This event is reportable under 1 O CFR 50.73(a)(2)(iv)(A), any event or condition that resulted in manual or automatic actuation of any of the systems listed in Section (a)(2)(iv)(B), specifically RPS, HPCS, and the Division 3 DG.
There were no safety consequences associated with the event describ.ed in this report. All plant equipment functioned as designed in response to the loss of L VDT feedback to the feedwater control system for TDRFP B. The unit entered Mode 3 upon the scram and all TS Limiting Conditions for Operation Required Actions were met throughout the event until the Prir:nary Containment to Secondary Containment and the Drywell to Primary Containment differential_pressures were restored.
Secondary Containment vacuui:n remained within limits throughout this event, filtering any potential leakage from the Primary Containment in the event of an accident. This condition is reportable under 1 O CFR 50.73(a)(2)(ii)(B), any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degra_des plant safety, due to Primary Containment to Secondary Containment and the Drywell to Primary Containment differential pressure TS limits being exceeded; and 10 CFR 50.73(a)(2)(v)(C), any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to control the release of radioactive material.
As described above, following automatic initiation of HPCS, the system was manually secured using station _procedures after verification that additional RPV injection was no longer required. Securing HPCS injection prevents auto restart of the system in the event of a subsequent low RPV level condition, rendering it inoperable. As the HPCS system is considered a single train safety system, this meets-the reportability requirements of 1 O CFR 50.73(a)(2)(v)(D), any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. The HPCS system remained available to restore RPV level manually as directed by operating procedure.
E.
Corrective Actions
(1) The failed LVDT was replaced on TDRFP 8, along with associated horizontal connecting hardware.
(2) A design change will be developed and installed to strengthen the connecting hardware to the TDRFP B operating cylinder LVDT such that it is adequate to withstand long-term cyclic loading.
F.
Previous Similar Occurrences There were no previous events identified involving failure of connecting hardware to LVDTs similar to the occurrence described in this licensee event report.
G.
Component Failure Data
Manufacturer: ABC Bearings Component Type: Spherco TRE3 Spherical Rod End Page _4_ of __...1_