05000390/LER-2018-005, Regarding Manual Reactor Trip Due to Failure of Reactor Coolant Pump to Transfer to Normal Power
| ML18353A744 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 12/19/2018 |
| From: | Simmons P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 2018-005-00 | |
| Download: ML18353A744 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 3902018005R00 - NRC Website | |
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{{#Wiki_filter:Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 December 19, 2418 10 cFR 50.73 ATTN. Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No.50-390 Subject: Licensee Event Report 390/2018-005-00, Manual Reactor Trip Due to Failure of Reactor Coolant Pump to Transfer to Normal Power This submittal provides Licensee Event Report (LER) 39012018-005-00. This LER provides details concerning a manual plant trip as a result of a Reactor Coolant Pump failing to transfer to its normal power supply. This condition is being reported in accordance with 10 CFR 50.73(aX2XivXA) as a manualactuation of the Reactor Protection System and the Auxiliary Feedwater Systems. There are no new regulatory commitments contained in this letter. Please direct any questions concerning this matter to Kim Hulvey, WBN Licensing Manager, at (423) 36s-7720. Paul Simmons Site Vice President Watts Bar Nuclear Plant Enclosure cc: see Page 2
U.S. Nuclear Regulatory Commission Page 2 December 19, 2018 cc (Enclosure): NRC Regional Administrator - Region ll NRC Senior Resident lnspector - Watts Bar Nuclear Plant
NRC FORM 366 (04-2018) .tls
- 1140,
.1lt- ' I t a rl U.S. NUCLEAR REGULATORY COMMISSiON LTCENSEE EVENT REPORT (LER) lAPPROVED By o S: 03/31/2020 I Estimated btrrden Per response to cornply witr tris mandatory mllectron request g0 hours. Reported lessons learned are incorporated into tre licensng process and bd back to industy. Send commenb regarding burden estimate to the liformation Services Branch (T-2 F43), U.s Nuclear Regulatory cornmisson, washrngton, DC 20s5s{001,u by e-mail to lnfocollecb. Resource@nrc.gov" and b ftre Desk otfi.o, office of information and Regulatory Afars, NEOB-10202, (31s0-0j04), office of Management and Budget, Washington, DC 20503. lf a means used to impose an informatiin co{lectjon does not display a cunenty valid OMB contol number, tre NRC may not conduct or sponsor, and a person is not required to respond to. the nrformaton cofiection.
- 1. Facility Name Watts Bar Nuclear Plant, Unit 1
- 2. Docket Number 05000390
- 3. Page OF 5
1
- 4. Ttue Manual Reactor Trip Due to Failure of Reactor Coolant Pump to Transfer to Normal power s. EvenI Lra[e
- 6. LEF( Number
- 7. Report Date
- 8. Other Facilities lnvolved Month Day Year year I Seeuentiat I
ruumber Rev No. Month Day Year Facility Name NA Docket Number 05000 10 27 I 2018 2019 -005
- - 00 12 19 2418 Facillty Name NA Docket Number 05000
- 9. Operating Mode 1ll' Ihis Report is Submifted Pursuant to the Requirements of i0 cFR 6: (check eu that enotut 1
tr zo.z2ol(b,) m2203(a)(3xi) H I X 50 73(a)(2xiixA) I n 50 73(a)(2XviiixA) n 2o.z2o1(d) I 20.22a3(aX3Xii) X s0.73(a)(2XiiXB) tr 50.73(a)(2)(viiiXB) n 2o.2zo3(axl ) I zo.z2a3(aX4) tr 50.73(a)(2xiii) n 50.73(a)(2XixXA) n 2o.22os(aX2Xi) f 50.36(c)(1XiXA) tr 50.73(aX2XivXA) tr 50.73(aX2Xx)
- 10. Power Level n 20.z2o3(aX2Xii) tr s0.36(c)(l XiiXA) tr 50.73(a)(2XvXA) tr rc.71(aX4) 21 tr 2a.z2o3(aX2Xiii) tr 50.36(cX2) n 50.73(aX2XvXB) tr rc.71(aX5) tr 2o.z2o3(aX2Xiv)
I 50.46(a)(3xii) n 50.73(aX2XvXC) n rc.Tl(a)(1) tr za.2zo3(aX2Xv) fJ 50.73(a)(2Xi)(A) n 50.73(a)(2XvXD) tr fi.TT(aX2Xi) tr zo.z2o3(aX2Xvi) fJ 50.73(a)(2XiXB) n 50.73(aX2Xvii) n fi.Tl(a)(2xii) f so zgt"ttzltrltcl I n oTHER Specify in Abstract betow or in =
l.
Plant operating conditions Before the Event
Watts Bar Nuclear Plant (WBN), Unit '1, was in Mode 1 at 21 percent rated thermal power. ll.
Description of Event
A. Event Summary On October 27,2018, at 1533 Eastern Daylight Time (EDT), Watts Bar Nuclear plant Un1 1 reactor was manually tripped due to a the number 3'Reacior Coolant pump (RCp) {EllS:P} normal feeder breaker-{EllS:BKR} failing to ctose during the planned fo*ei transfer to unit power {EllS:EA} during startup. Concurrent with the reactor trip, the Auxiliary Feedwater (AFW) {EllS:BA} system actuated as designed. All safety systems responded as designed. This event is being reported in accordance with 10 CFR 50.73(a)(2)(iv)(A), as a manual actuation of the Reactor Protection System (RPSXEIIS:JC) and tn automatic actuation of the AFW system.
Status of structures, components, or systems that were inoperable at the start of the event and that contributed to the event
No inoperable systems contributed to this event.
Dates and approximate times of occurrences
Date Time Event B. C. (EDr 1 533 10t27 t2018 10t27 t2018 10t27 t2018 10t27 na18 Manually tripped Unit l due to Bus Transfer. lnitiated 1-E-0, lnjectiofl, immediate actions. Loss of RCP 3 during Reactor Trip or Safety D. E. 1536 Transition to 1-ES-O.1, Reactor Trip Response. 1539 Main steam lsolation valves (Mslvs) closed to control Reactor coolant system (RCS) cooldown. 1652 cornpleted NRc Notification, EN s3697
Manufacturer and model number of each component that failed during the event
No equipment failures contributed to this event.
Other systems or secondary functions affected
Secondary systems functioned as expected
F. Method of discovery of each component or system failure or procedural error
During the p-ost trip investigation, it was discovered that the normal feeder breaker for the number 3 RcP was left in the racked down (disconnected)position. G. Failure mode, mechanism, and effect of each failed component There were no failed components associated with this event.
H. Operator actions
Operations personnel promptly stabilized the plant following the plant trip.
l. Automatically and manually initiated safety system responses
Operations personnel tripped Unit 1, as procedurally required, when RCp 3 failed to transfer to its normal power source..During the trip response, the RCS was cooling down faster than desired and operations closed the MSIVs to control RCS cooldown.
Cause of the Event
A. cause of each component or system failure or personnel enor There were no equipment failures associated with this event. The apparent cause to this event was operations personnelfailed to properly implement the requirements of system status control procedures.
The apparent cause to this event was operations personnelfailed to properly implement the requirements of system status control procedures.
Analysis of the Event
During a normal start up at WBN, after the main generator has been synchronized to the grid, the power source for the RCPs is transferred from the Common Station Service Transformers (CSSTs, offsite power) to the Unit Station Service Transformers (USSTs) which ire powered by the main generator. On October 27,2018, prior to performing the above described power lr?.nslet'.gp.erations personnel had briefed on actions to perf6rm in the event the power transfer failed, which included manually tripping the reac{or. Whbn the number 3 RCp failed to transfer from its alternate to normal power sypply, a manual reactor trip was initiated. Operations personnel were able to prompfly stabilize the plant following ttiis trip.
- - r- -'
ilt. lv.
inoperable, Efl estimate of the elapsed was returned to service V. Subsequent to the event, it was determined that the configuration of the number 3 RCp normal feeder breaker was not being controlled using written instiuctions, which is not in accordance with plant procedures.
Assessment of Safety Consequences
This event is bounded by a partial loss of fgrced reactor coolant flow, which is an anticipated operational occurrence described in the Final Safety Analysis neport (FSAR). A pioO"Oiti.tic risk assessment for this event determined the incremenial inciease in cord damage fiequency to be very small. A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event All safety systems operated as designed during this event. B. For events that occurred when the reactor was shut down, availability of systems or components needed to shut down the reactor and maintain safe snuiOown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident Not applicable. c. For failure that rendered a train of a safety system time from the discovery of the failure until the train vt. Not applicable. Conective Actions This condition was entered into the TVA Corrective Action Program (CAp) and is being tracked under Condition Report (CR) 1460667. A. lmmediate Corrective Actions Operations personnel promptly stabilized the plant following the reactor trip. lmmediate corrective actions included procedure enhancements for atinCp board transfers to ensure required breakers are racked up and closing springs are charged with no relays actuated. B. Corrective Actions to Prevent Recurrence or to reduce probability of similar events occurring in the future Additionaltraining on status control processes will be provided to operations personnel.
Vll. Previous Similar Events at the Same Site Manual reactor trips of wBN unit lrvere reported in LER 3got2o17-oo4-ol when the RCp power transfer failed.during-plant startup. These trips were the result of an incorrecly configufi ;t associated with the RCP Board ic control circuit. while the result is simitar, the cause that led to the need to trip the reactor is different than this earlier event. Vlll. Additionallnformation There is no additional information. lX. Commitments There are no new commitments^ NRC FORM 3664 (04_2018) 5 Page 5 of }}