Q78 — CCW Abnormality RCP Bearing Temperature Time Limit
000026A2.06 (3.1)
Given:
• Unit 2 is at 100% Power.
• 22 Component Cooling Water Pump is cleared and tagged for maintenance.
At 1000:
• Bezel Alarm, SURGE TANK LEVEL HI-LO, is received.
• CCW Surge Tank Level is 35 % and lowering.
• Bezel Alarm, 21 (22) CC HDR PRESSURE LO, is received.
• OHA D-37, RCP BRG CLG HDR TEMP HI, is illuminated
• The crew has entered S2.OP-AB.CC-0001, Component Cooling Abnormality.
• The highest RCP Motor Bearing temperature is 140 °F and rising at 5 °F/minute
At 1005:
• Makeup to the CCW Surge Tank has been initiated and level is being maintained at approximately 40 %.
• OHAs D-20 through D-23; 21-24 RCP BRG CLG WTR FLO LO illuminate.
In accordance with S2.OP-AB.CC-0001, the EARLIEST time that the CRS will need to take action to prevent damage to the RCPs will be at ______.
• Unit 2 is at 100% Power.
• 22 Component Cooling Water Pump is cleared and tagged for maintenance.
At 1000:
• Bezel Alarm, SURGE TANK LEVEL HI-LO, is received.
• CCW Surge Tank Level is 35 % and lowering.
• Bezel Alarm, 21 (22) CC HDR PRESSURE LO, is received.
• OHA D-37, RCP BRG CLG HDR TEMP HI, is illuminated
• The crew has entered S2.OP-AB.CC-0001, Component Cooling Abnormality.
• The highest RCP Motor Bearing temperature is 140 °F and rising at 5 °F/minute
At 1005:
• Makeup to the CCW Surge Tank has been initiated and level is being maintained at approximately 40 %.
• OHAs D-20 through D-23; 21-24 RCP BRG CLG WTR FLO LO illuminate.
In accordance with S2.OP-AB.CC-0001, the EARLIEST time that the CRS will need to take action to prevent damage to the RCPs will be at ______.
A. 1002
B. 1005
C. 1007
D. 1010
▶ Show Answer & Explanation
✓ C. Correct. The procedure requires stopping the RCPs if motor bearing temperature reaches 175°F. At 1000 the bearing temperature was 140°F and rising at 5°F/minute, therefore 7 minutes later the trip requirement of 175°F will be met.
✗ A. Plausible because 2 minutes was previously the time to stop RCPs if both seal injection flow and thermal barrier flow were lost concurrently. Incorrect, as seal injection flow has not been lost.
✗ B. Plausible because the abnormal procedure requires immediately stopping the pumps if CCW Surge Tank Level can not be maintained > 38%. Incorrect in that as of 1005, surge tank level is being maintained > 40% with makeup initiated. Candidate may also believe that once the low flow alarms (OHAs D20-23) come in at 1005, the RCPs need to be immediately stopped. Incorrect as it is required 5 minutes after the OHAs come in.
✗ D. Plausible as the procedure requires stopping the RCPs if 5 minutes have elapsed since the "RCP BRG CLG WTR FLO LO" alarm(s) actuated.
Ref: S2.OP-AB.CC-0001(Q), Component Cooling Abnormality | LO: N/A | Source: New | Cognitive: Comprehension | SRO-Only: Requires specific knowledge of content & basis of abnormal procedure
Connections
- Related systems: CCW, RCPs
- Related procedures: AB.CC-0001 — Loss of Component Cooling Water, S2.OP-AR.ZZ-0004 — Alarm Response Procedure
- Related exam: 2020 NRC Written Exam