ML071350104
| ML071350104 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 03/26/2007 |
| From: | Dominion Nuclear Connecticut |
| To: | David Silk Operations Branch I |
| Sykes, Marvin D. | |
| Shared Package | |
| ML060800095 | List: |
| References | |
| Download: ML071350104 (1) | |
Text
Question Deletion Question #65 (AMSAC) was deleted after a discussion with the NRC chief examiner.
The Question appeared as follows on the students exam:
- 65) The plant is stable at 48% power, when the following sequence of events occurs:
Time Event T=O seconds:
T+30 seconds:
T+40 seconds:
Turbine impulse pressure channel 3MSS-PT505 fails low.
During the resulting transient, all main feedwater is lost due to low feed pump suction pressures.
The low-low SG level reactor trip setpoint is reached, but the reactor fails to trip, and current SG narrow range levels are as follows:
0 0
0 e
SG A: 12% and decreasing.
SG B: 16% and decreasing.
SG C: 14% and decreasing.
SG D: 13% and decreasing.
How will the AMSAC System respond to this event?
A. AMSAC will trip the reactor with no time delay, and start the AFW pumps in 60 seconds.
B. AMSAC will trip the turbine in 30 seconds, and start the AFW pumps in 60 seconds.
C. AMSAC will not actuate, since it was procedurally in Bypass at the start of the event.
D. AMSAC will not actuate, since indicated turbine power was below C-20 for the required time before the ATWS event occurred.
The listed correct answer, B, includes time-delays that are the delays assumed in accident analysis for these actions, but NOT the time delays associated with AMSAC circuitry. Therefore, there is no correct answer.