RPCB(LOFP)

Question 1

What are the exit conditions for RPCB?

Answer 1

Condition 1:

• Power is stable and decision has been made to raise power
• CEAs are above the Transient Insertion Limit
• AOP directs entry into 40OP-9ZZ05

Condition 2:

• Power is stable and decision has been made to maintain current plant power
• CEAs are above the Transient Insertion Limit
• AOP directs entry into 40OP-9ZZ05

Condition 3:

• Reactor power is stable
• CEAs are above the Transient Insertion Limit
• Normal Reg Group CEA overlap has been restored.
• AOP directs entry into 40OP-9ZZ04 (M2 to M1) or 40OP-9ZZ07 (M1 to M3)

Question 2

State the rx trip criteria contained in RPCB.

Answer 2

• ≥ 74%: MFP trips and RPCB fails to actuate (auto and manual)
• CEA deviates from its subgroup by > 6.6” and any Reg Groups are below the Transient Insertion Limits
• Both MFPs trip
• SGWL approaching trip setpoints (44.2% WR or 91% NR)
• CPC ASI (Pt 0187) > ± 0.45 and trending to ± 0.5 (if Aux Trip enabled, above the Rule of 45)
• Turbine load ≤ 410 MW (Vacuum is 4-5” HgA for > 1 hour or > 5” HgA)

Question 3

How is RPCB maunally actuated?

Answer 3

Press Drop subgroups and either LLR or LOFP.

Question 4

Describe manual actions reqruired if the turbine setback did not occur, or if < 74% rx power and CEAs didnt insert as expected?

Answer 4

If setback-runback did not occur, reduce Turbine load with the potentiometer until MT load is < 65%.

If CEAs didn’t insert as expected, insert CEAs as necessary to match Rx and Turbine power.

Question 5

How is load control placed back on the turbine following a RPCB?

Answer 5

Setback is begun by a contact closure (latches in until cleared). While a load setback is in effect, EHC control panel “load limit limiting” light will be lit.

The setback causes a turbine increase inhibit and is cleared once the input from RPCS is no longer present (press Auto Actuate OOS and Test/Reset)

Then turn the “load limit set” potentiometer CCW until it takes control(,60%). The “load limit set” pot can then be turned CW to remove its effect on increasing load.

Question 6

Describe the application of TS 3.1.7 CEA alignment.

Answer 6

DOes not apply for 2 hrs following a RPCB.

Must restore RG 4 to [RG 3 - 95”] or 95” withdrawn. Ensure you meet CEA transient insertion limits.