NN (Non Class 120V AC Instrument Power) Flashcards
All control input transmitters to the Digital Feedwater Control system are in service. A loss of NNN-D11 occurs. Which of the following describes the operator action(s), if any, that need to be taken to stabilize the plant?
A. Take manual speed control of MFP A and B
B. No operator action required
C. Take manual control of DFWCS A
D. Take manual control of DFWCS A and B
Answer: B
Plant is at 90% power. Loss of Non-Class 120VAC power to NNN-D15 occurs. With NO operator action, which one of the following will occur?
A. RPCB initiates causing turbine load to be setback and runback as necessary to balance Tavg and steam header pressure.
B. Reactor trip occurs on high RCS pressure due to a main turbine trip.
C. RPCB initiates causing the main turbine to be setback to 60% with no runback occurring.
D. Reactor trip occurs on low steam generator level.
Answer: D
Unit 1 is operating at 85% power. A loss of NNN-D12 occurs. Both MFPs remain in operation. Based on these conditions, the operating crew MUST:
A. take appropriate action to stop the ongoing boration.
B. take appropriate action to stop the ongoing dilution.
C. trip a MFP and verify that a RPCB (LOFP) is generated.
D. trip a MFP, manually insert CEA’s and verify turbine setback.
Answer: A
Unit 2 is at 100% power The Unit has experienced a loss of NNN-D12 All other systems are operating normally Charging pump suction will automatically switch to…..
A. CH-UV-514 open and CH-UV-501 open (must be manually closed).
B. CH-UV-514 open and CH-UV-501 closed.
C. CH-HV-536 open and CH-UV-501 closed.
D. CH-HV-536 open and Ch-UV-501 open (must be manually closed).
Answer: B
Unit 1 is operating at rated power. A loss of NNN-D12 occurs. Shortly after this, the ‘B’ MFP trips. Based on these conditions, with no operator action, the operating crew can expect…
A. A RPCB followed by a reactor trip due to secondary power (steam demand) being significantly higher than primary power.
B. Plant stabilization after a manual RPCB.
C. Plant stabilization after an automatic RPCB.
D. A RPCB followed by a reactor trip due to secondary power (steam demand) being significantly lower than primary power.
Answer: A
Unit 1 is operating at rated power. A loss of NNN-D15 occurs. Based on these conditions, the operating crew MUST:
A. transfer speed control of the “A” MFP to manual.
B. trip the “A” MFP and verify a RPCB (LOFP) actuates.
C. trip the “A” MFP, manually insert CEAs and runback turbine load to 65%.
D. verify a RPCB (LOFP) actuates when the “A” MFP speed drops below 3000 rpm.
Answer: B
Which one of the following describes how a loss of NNN-D12 effects the operation of the RPCS?
A. The system will function to drop CEAs and runback the turbine and the setback feature will not function.
B. A turbine setback and runback will function, the CEAs will not drop.
C. The system will function to drop CEAs and all turbine features will not operate.
D. The system will function to drop CEAs, the runback feature will not function and the turbine will setback.
Answer: D
