05000390/LER-2016-001, Regarding Channel Mode Switch in Incorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor Inoperable
| ML16069A205 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 03/09/2016 |
| From: | Walsh K Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 16-001-00 | |
| Download: ML16069A205 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3902016001R00 - NRC Website | |
text
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 March 9, 2016 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
10 cFR 50.73 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390 Licensee Event Report 390/2016-001-00, Channe! Mode Switch in lncorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor lnoperable This submittal provides Licensee Event Report (LER) 390/2016-001-00. This LER provides details concerning placing the mode selector switch for the Lower Containment Atmosphere Particulate Radiation Monitor in the wrong position, resulting in the monitor being inoperable for a period longer than allowed by Technical Specification 3.4.15. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B).
Please direct any questions concerning this matter to Gordon Arent, WBN Licensing Director, at (423) 365-2004.
Site Vice President Watts Bar Nuclear Plant Enclosure cc: see Page 2
U.S. Nuclear Regulatory Commission Page 2 March 9, 2016 cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident lnspector - Watts Bar Nuclear Plant
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (1 1-2015)
..f *'.'g i% LT.ENSEE EVENT REP'RT (LER)
?4-\\(D n.ar, APPROVED BY OMB: NO. 3{50-0104 EXPIRES: 1013112018
, 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 1
- 2. DOCKET NUMBER 05000390
- 3. PAGE 10F5
- 4. TITLE Channel Mode Switch in lncorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor lnoperable
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTHI DAY I YEAR YEAR I 'fttffHfL REV NO.
MONTH I DAY YEAR FACILIW NAME I
OOCXET NUMBER N/A lrun 01 12 I 2016 2016 -001
- - 00 03 09 2016 FACTLTTY NAME I
DOCKET NUMBER N/A 105000
- 9. OPERATING MODE II.THISREPORTISSUBMITTEDPURSUANTTOTHEREQUIREMENTSOFt0CFRS:
(Checkallthatapply) 1 tl 20.2201(b) tr zo.22o3(aX3Xi) tr 50.73(ax2xiixA) tr 50.73(aX2XviiiXA) tr 2o.2zo1(d) tr 2o.22os(aX3Xii) tr 50.73(aX2Xii)(B) tr 50.73(aX2XviiiXB) tr 2o.22os(aX1) tr 2o.22os(a)(4) tr s0.73(ax2)(iii) tl s0.73(a)(2XixXA) tr 2o.z2os(aX2X.)
tr 50.36(cxl XIXA) tr s0.73(a)(2)(ivXA) tr 50.73(aX2Xx)
- 10. POWER LEVEL 100 n 20.2203(a)(2Xii) tr 50.36(cXlXiiXA) tr 50.73(aX2Xv)(A) tr nl1(aX4) tr 2o.z2o3(aX2Xiii) tr s0.36(cX2) n 50.73(aX2Xv)(B) tl rc.21(aX5) tr 20.2203(aX2)(iv) tr 50.46(ax3xii) tr s0.73(aX2XvXc) tr ts.rr(a)(1) tr 2o.2zo3(aX2Xv) tr 50.73(aX2)(iXA) tr 50.73(aX2XvXD) tr B.r7(aX2)(.)
tr 2o.22os(aX2)(vi)
X 50.73(aX2XiXB) tr 50.73(aX2Xvii) tr ft.rt(ax2xii) tr 50.73(ax2xi)(c) tr OTHER Specify in Abstract below or in Action 3.4.15.8 requires when a containment atmosphere particulate radioactivity monitor is inoperable that containment atmosphere grab samples are to be taken and analyzed every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or to perform an RCS inventory balance every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and to restore the containment atmosphere particulate radioactivity monitor to operable status in 30 days.
With the mode switch for 1-RM-90-106A in the "DlFF" position, high and low radiation signals were discriminated by the monitor, and the alarm from the containment atmosphere particulate radioactivity monitor was effectively blocked. With the monitor alarm blocked, this monitor is considered to be INOPERABLE.
When the mode switch was placed in the "DlFF" position (monitor INOPERABLE), actions were required by TS 3.4.15.8 to take containment atmosphere samples every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or to perform an RCS inventory balance every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. While entry into TS 3.4. 1 5. B was not recognized, the plant does perform an RCS inventory balance at least every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The monitor was not, however, returned to operable status in the 30 days required by TS Action 3.4.15.8.2. Accordingly, a condition prohibited by Technical Specifications occurred.
ASSESSMENT OF SAFETY CONSEQUENCES
A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event During the time period that the alarm function was lost for 1-RM-90-106A, other means of detecting RCPB leakage remained operable. The containment pocket sump level monitor remained operable, along with the non-credited containment atmosphere radioactivity monitor. ln addition, during this time period, RCS inventory balances were performed every shift, with no indication of increasing RCS leakage. Accordingly, the safety consequences of this event are minimal.
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 Not applicable.
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) Conective Action Program (CAP) and is being tracked under condition report (CR) 1 124181.
V.
A. lmmediate Corrective Actions Upon identifying the incorrect position of the channel mode switch, the switch was placed in the correct position.
B. Corrective Actions to Prevent Recurrence Plant procedures will be revised to check the position of the mode selector switch for the containment radiation monitors 1/2-RM-90-106A and 1/2-RM-90-112A every shift.
VII. ADDITIONALINFORMATION A. Previous similar events at the same plant On December 21,2015, WA submitted LER 390-2015-006, "Source Range Level Trip Channels (N-31 and N-32) lnoperable During Plant Startup." This LER describes a condition prohibited by Technical Specifications where Watts Bar Unit 1 performed a reactor start-up with the source range (SR) reactor trip in the bypass position (SR trip inoperable). This bypass condition was not recognized until after the reactor startup was completed. The cause of this event was that operators failed to identify a bypassed safety function during reactor start-up due to inadequate tracking of essential information. While the event described in LER 2015-006 is somewhat different than this LER, and had other contributing causes, it involves a bypassed safety function not being recognized. Because the issue described in this LER involved an undocumented switch reposition, the corrective actions in LER 2015-006 would not be expected to have prevented this event.
B. Additional lnformation None.
C. Safety System Functional Failure Consideration This condition did not result in a safety system functionalfailure.
D. Scrams with Complications Consideration There was no scram associated with this report.
VIII. COMMITMENTS
None.
NRC FORM 3664 (1 1-2015)
Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 March 9, 2016 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
10 cFR 50.73 Watts Bar Nuclear Plant, Unit 1 Facility Operating License No. NPF-90 NRC Docket No. 50-390 Licensee Event Report 390/2016-001-00, Channe! Mode Switch in lncorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor lnoperable This submittal provides Licensee Event Report (LER) 390/2016-001-00. This LER provides details concerning placing the mode selector switch for the Lower Containment Atmosphere Particulate Radiation Monitor in the wrong position, resulting in the monitor being inoperable for a period longer than allowed by Technical Specification 3.4.15. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B).
Please direct any questions concerning this matter to Gordon Arent, WBN Licensing Director, at (423) 365-2004.
Site Vice President Watts Bar Nuclear Plant Enclosure cc: see Page 2
U.S. Nuclear Regulatory Commission Page 2 March 9, 2016 cc (Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident lnspector - Watts Bar Nuclear Plant
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (1 1-2015)
..f *'.'g i% LT.ENSEE EVENT REP'RT (LER)
?4-\\(D n.ar, APPROVED BY OMB: NO. 3{50-0104 EXPIRES: 1013112018
, 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 1
- 2. DOCKET NUMBER 05000390
- 3. PAGE 10F5
- 4. TITLE Channel Mode Switch in lncorrect Position Renders Lower Containment Atmosphere Particulate Radiation Monitor lnoperable
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTHI DAY I YEAR YEAR I 'fttffHfL REV NO.
MONTH I DAY YEAR FACILIW NAME I
OOCXET NUMBER N/A lrun 01 12 I 2016 2016 -001
- - 00 03 09 2016 FACTLTTY NAME I
DOCKET NUMBER N/A 105000
- 9. OPERATING MODE II.THISREPORTISSUBMITTEDPURSUANTTOTHEREQUIREMENTSOFt0CFRS:
(Checkallthatapply) 1 tl 20.2201(b) tr zo.22o3(aX3Xi) tr 50.73(ax2xiixA) tr 50.73(aX2XviiiXA) tr 2o.2zo1(d) tr 2o.22os(aX3Xii) tr 50.73(aX2Xii)(B) tr 50.73(aX2XviiiXB) tr 2o.22os(aX1) tr 2o.22os(a)(4) tr s0.73(ax2)(iii) tl s0.73(a)(2XixXA) tr 2o.z2os(aX2X.)
tr 50.36(cxl XIXA) tr s0.73(a)(2)(ivXA) tr 50.73(aX2Xx)
- 10. POWER LEVEL 100 n 20.2203(a)(2Xii) tr 50.36(cXlXiiXA) tr 50.73(aX2Xv)(A) tr nl1(aX4) tr 2o.z2o3(aX2Xiii) tr s0.36(cX2) n 50.73(aX2Xv)(B) tl rc.21(aX5) tr 20.2203(aX2)(iv) tr 50.46(ax3xii) tr s0.73(aX2XvXc) tr ts.rr(a)(1) tr 2o.2zo3(aX2Xv) tr 50.73(aX2)(iXA) tr 50.73(aX2XvXD) tr B.r7(aX2)(.)
tr 2o.22os(aX2)(vi)
X 50.73(aX2XiXB) tr 50.73(aX2Xvii) tr ft.rt(ax2xii) tr 50.73(ax2xi)(c) tr OTHER Specify in Abstract below or in 1il.
D. Manufacturer and Model Number of Components that Failed There were no failed components associated with this event.
E. Other Systems or Secondary Functions Affected
There were no systems or secondary functions affected by this event.
F. Method of discovery of each Component or System Failure or Procedural Error
The switch reposition was found during the performance of routine maintenance.
G. Failure Mode and Effect of Each Failed Component There were no component failures associated with this event.
H. Operator Actions
Upon identiffing the incorrect position of the switch, its position was corrected.
l. Automatically and Manually lnitiated Safety System Responses There were no automatic or manual system responses associated with this event.
CAUSE OF THE EVENT
A. The cause of each component or system failure or personnel error, if known.
There were no component or system failures as a result of this event notification. The most likely cause of the switch reposition was inadvertent manual operation.
B. The cause(s) and circumstiances for each human performance related root cause.
A cause analysis was performed to determine when the switch was repositioned. Based on a review of plant computer history, it was determined the switch was repositioned on December 8, 2015 at 1654 EST. Work was being performed during this time on the same control room panel that the affected switch was located. However, no maintenance or operator instructions specified that the switch was to be repositioned. lnterviews with personnel working in the control room at this time did not identify an individualwho repositioned the switch.
ANALYSIS OF THE EVENT
Reactor Coolant System (RCS) leakage detection instrumentation is required by TS 3.4.15. The purpose of this instrumentation is to monitor for reactor coolant pressure boundary (RCPB) leakage as soon after occurrence as practical to minimize the potential for propagation of a leak to a gross failure of the RCPB.
The instruments credited in TS 3.4.15 with monitoring RCPB leakage are the containment pocket sump level monitor and one lower containment atmosphere particulate radioactivi$ monitor (1-RM-90-106A). TS tv.
Action 3.4.15.8 requires when a containment atmosphere particulate radioactivity monitor is inoperable that containment atmosphere grab samples are to be taken and analyzed every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or to perform an RCS inventory balance every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and to restore the containment atmosphere particulate radioactivity monitor to operable status in 30 days.
With the mode switch for 1-RM-90-106A in the "DlFF" position, high and low radiation signals were discriminated by the monitor, and the alarm from the containment atmosphere particulate radioactivity monitor was effectively blocked. With the monitor alarm blocked, this monitor is considered to be INOPERABLE.
When the mode switch was placed in the "DlFF" position (monitor INOPERABLE), actions were required by TS 3.4.15.8 to take containment atmosphere samples every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or to perform an RCS inventory balance every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. While entry into TS 3.4. 1 5. B was not recognized, the plant does perform an RCS inventory balance at least every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The monitor was not, however, returned to operable status in the 30 days required by TS Action 3.4.15.8.2. Accordingly, a condition prohibited by Technical Specifications occurred.
ASSESSMENT OF SAFETY CONSEQUENCES
A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event During the time period that the alarm function was lost for 1-RM-90-106A, other means of detecting RCPB leakage remained operable. The containment pocket sump level monitor remained operable, along with the non-credited containment atmosphere radioactivity monitor. ln addition, during this time period, RCS inventory balances were performed every shift, with no indication of increasing RCS leakage. Accordingly, the safety consequences of this event are minimal.
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 Not applicable.
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) Conective Action Program (CAP) and is being tracked under condition report (CR) 1 124181.
V.
A. lmmediate Corrective Actions Upon identifying the incorrect position of the channel mode switch, the switch was placed in the correct position.
B. Corrective Actions to Prevent Recurrence Plant procedures will be revised to check the position of the mode selector switch for the containment radiation monitors 1/2-RM-90-106A and 1/2-RM-90-112A every shift.
VII. ADDITIONALINFORMATION A. Previous similar events at the same plant On December 21,2015, WA submitted LER 390-2015-006, "Source Range Level Trip Channels (N-31 and N-32) lnoperable During Plant Startup." This LER describes a condition prohibited by Technical Specifications where Watts Bar Unit 1 performed a reactor start-up with the source range (SR) reactor trip in the bypass position (SR trip inoperable). This bypass condition was not recognized until after the reactor startup was completed. The cause of this event was that operators failed to identify a bypassed safety function during reactor start-up due to inadequate tracking of essential information. While the event described in LER 2015-006 is somewhat different than this LER, and had other contributing causes, it involves a bypassed safety function not being recognized. Because the issue described in this LER involved an undocumented switch reposition, the corrective actions in LER 2015-006 would not be expected to have prevented this event.
B. Additional lnformation None.
C. Safety System Functional Failure Consideration This condition did not result in a safety system functionalfailure.
D. Scrams with Complications Consideration There was no scram associated with this report.
VIII. COMMITMENTS
None.
NRC FORM 3664 (1 1-2015)