05000391/LER-1917-004, Regarding Manual Reactor Trip Due to Inoperable Rod Position Indication
| ML17268A210 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 09/25/2017 |
| From: | Simmons P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 17-004-00 | |
| Download: ML17268A210 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) |
| 3911917004R00 - NRC Website | |
text
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 September 25,2017 10 cFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391
Subject:
Licensee Event Report 39112017-004-00, Manual Reactor Trip Due to
!noperable Rod Position lndication This submittal provides Licensee Event Report (LER) 39012017-004-00. This LER provides details concerning a manual reactor trip that occurred when rod position indication was determined to be inoperable. This report is being submitted in accordance with 1 0 cFR 50.73(a)(2)(ivXA).
There are no regulatory commitments contained in this letter. Please direct any questions concerning this matter to Kim Hulvey, WBN Licensing Manager, al (423) 365-7720.
Respectfully,
@k Paul Simmons Site Vice President Watts Bar Nuclear Plant Enclosure cc: See Page 2
U.S. Nuclear Regulatory Commission Page 2 September 25,2017 cc (Enclosure):
NRC Regional Administrator - Region Il NRC Senior Resident lnspector - Watts Bar Nuclear Plant
NRC FORM 366 (04-2017)
- t ^*
tt"r.rro-iW U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
APPROVED BY OMB: NO.3150-0104 ExptRES: 0381t2020
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 1. FACILITY NAME Watts Bar Nuclear Plant, Unit 2
- 2. DOCKET NUMBER 0500039 1
- 3. PAGE 10F 4
- 4. TITLE Manual Reactor Trip Due to lnoperable Rod Position lndicatron
- 5. EVENT DATE
- 5. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTHI ONV I YENR YEAR I ttir'rtJJfl REV NO.
MONTH I ONY YEAR FACILITY NAME N/A 105000 07 25 I 2017 2017 004
- - 00 09 25 2017 FACILITY NAME I
OOCXef r.tilfr,teER losooo
- 9. OPERATING MODE 1'l'THISREPORTISSUBMITTEDPURSUANTTOTHEREQUIREMENTSOFIOGFRg:
(Checkaltthatappty) 3 n 20 zzo1(b) t] zo 22o3(aX3Xi) tr 50 73(aX2XiiXA) tr 50 73(a)(2)(viii)(A) tr 20 z2o1 (d) tr 20 zzo3(aX3Xii) tr 50.73(aX2)(iiXB) tr 50 73(aX2)(v.i.)(B) tr 20 z2o3(aX1) tr zo 22o3(a)(4) tr 50 73(a)(2xiii) tr 50 73(a)(2)(ixXA) tr zo 22o3(aX2Xi) tr 50 36(cx1)(iXA) tr 50 73(a)(2XivXA) tr 50 73(aX2)(x)
- 10. POWER LEVEL t] zo z2o3(aX2)(ii) tr 50 36(cxl XiiXA) tr 50 73(a)(2)(v)(A) tr rc 11 (aX4) tr 2o.2zo3(a)(2)(rii)
I 50 36(c)(2) tr 50 73(aX2Xv)(B) tr rc 21 (aXs) tr 20 zzo3(aX2Xiv) tr 50 46(ax3xii) tr 50 73(aX2)(vXC) tl n rr(a)(1) tr zo.z2o3(aX2Xv) tr 50 73(aX2XiXA) tr 50 73(aX2Xv)(D) n B TT(aX2Xi) tr zo z2o3(aX2)(vi) tr 50 73(aX2)(i)(B) tr 50 73(aX2Xvii) tl fi 17(ax2)(ii) tr 50 73(ax2xi)(c) tr OTHER Specify in Abstract betow or in All safety systems and secondary functions operated as designed.
F. Method of discovery of each Component or System Failure or Procedural Error
An investigation following the manual reactor trip identified the failed logic card.
G. Failure Mode and Effect of Each Failed Component The cause of the logic card failure is under investigation by Westinghouse.
H. Operator Actions
Upon determining a group demand indication variance of greater than two steps, the reactor trip breakers were opened by inserting a Manual Reactor Trip. Operations personnel promptly worked through the emergency procedures and reentered normal plant operating procedures for this' condition.
l. Automatically and Manually lnitiated Safeg System Responses The reactor trip breakers were opened by manually tripping the reactor. No automatic actuations of safety equipment were required or occurred.
III. CAUSE OF THE EVENT
A. The cause of each component or system failure or personnel error, if known.
The failed logic card was shipped to the vendor for testing and failure analysis.
B. The cause(s) and circumstances for each human performance related root cause.
No human performance issues are related to this trip.
IV. ANALYSIS OF THE EVENT
During a normalstart up at WBN, operations personnel commenced withdrawing Control Bank A. Within 3 steps, operations personnel determined a rod position deviation occurred and opened the reactor trip breakers in accordance with requirements. During the event the reactor was not critical, and cooling was being provided by the AFW system. The reactor trip was uncomplicated. After extensive troubleshooting and analysis by the vendor, the slave cycler card failure was identified.
V. ASSESSMENT OF SAFETY CONSEQUENCES
This event is bounded by a rod cluster control assembly misalignment, which is an anticipated operational occurrence described in the Final Safety Analysis Report (FSAR).
A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event Allsafety 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 shutdown the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident Allsafety systems operated as designed during this event.
C. For failure that rendered a train of a safety system inoperable, an estimate of the elapsed time from the discovery of the failure until the train was returned to service Not applicable.
VI. CORRECTIVE ACTIONS
This event was entered into the Tennessee Valley Authority (TVA) Corrective Action Program and is being tracked under Condition Report (CR) 1320840.
A. lmmediate Corrective Actions When the rod position deviation was identified, the reactor trip breakers were opened.
Subsequent investigation determined that a logic card had failed, and the card was replaced.
B. Corrective Actions to Prevent Recurrence or to Reduce Probability of Similar Events Occurring in the Future Additional logic cards associated with the rod controlsystem will be tested in accordance with the preventative maintenance strategy.
VII. PREVIOUS SIMILAR EVENTS AT THE SAME SITE
An automatic reactor trip due to actuation of the Over Temperature Delta temperature bistables was reported to the NRC in LER 390/2016-004 dated May 23,2016. This event was caused by a failure of a Valve Position Limit up/down counter circuit card in the Analog Electro-Hydraulic Turbine Control System which resulted in the closure of the turbine high pressure governor valves, resulting in an automatic reactor trip and turbine trip on WBN1. The event described in this LER is different in that it involves a component failure in an unrelated plant system.
VIII. ADDITIONAL INFORMATION
None.
IX. COMMITMENTS None.Page 4 of 4