Mode 5 To 3 Flashcards
What are the maximum pressure/temperature limit for the CS pump during SDC operations?
CAUTION
RCS pressure shall be maintained less than 250 psia or RCS temperature shall be maintained less than 200°F when a Containment Spray Pump is aligned to the Shutdown Cooling System to preclude pump damage.
Describe the temperature requirements and their bases for initiating and securing SDC.
CAUTION
Operating the Shutdown Cooling System with RCS temperature greater than 300°F will result in thermal binding of the LTOP valves.
Initiating Shutdown Cooling:
• Shutdown Cooling Loop Suction Isolations may be opened when T-cold is less than 350°F and Pressurizer Pressure is less than 385 psia.
• Operating a LPSI or CS Pump on Shutdown Cooling with RCS temperature less than 300°F will minimize mechanical seal degradation.
• For maximum SDC pump seal life, limit SDC temperature to less than 180°F.
• For SDC System operation greater than 4 days, limit SDC temperature to less than 135°F.
Securing Shutdown Cooling:
• During RCS heatup, RCS flow through the SDC system shall be stopped before RCS temperature is greater than 300°F to prevent thermal binding of the LTOP valves.
Describe how purification flowrate through the letdown line is increased.
Shutdown Cooling Purification is aligned with the VCT in operation or with the VCT secured. In both cases, Letdown Purification flow is controlled in the following manner:
• Adjust CHN-PIC-201, Letdown Backpressure Controller to maintain the desired purification flow.
• IF an increase in letdown purification flow is necessary and CHN-PIC-201 is fully open, THEN raise the Δp across the shutdown purification system to obtain adequate letdown flow as follows:
1) Throttle closed on a loop injection valve on the operating SDC Train: SDC Train A – SIA-UV-635 and/or SIA-UV-645 SDC Train B – SIB-UV-615 and/or SIB-UV-625
2) Maintain Shutdown Cooling flow per the procedure in progress.
• It is recommended to close down on one injection valve first until it is fully closed, the throttle on the second valve. This minimizes any flow rate resonance or cavitation across the injection valves.
Describe how SDC flow is throttled and to what value it may be lowered.
When Shutdown Cooling (SDC) is established, a decision must be made on whether to use single loop or two loop injection. The decision is made with Outage Management, RP and Containment Coordinator input. Assuming two loop injection (both injection valves on that train open), the following guidance is provided if throttling SDC (e.g. - to increase Δp for Letdown purification flow) becomes necessary:
• When throttling SDC flow, the recommended method is to close down on one injection valve first until it is fully closed, then throttle closed on the second valve. This minimizes any flow resonance or cavitation across the injection valves.
While the plant is in Mode 5, SDC flow may be as low as 3780 gpm (3780 to 5000 gpm). However, prior to increasing RCS temperature above 210°F (Mode 4 entry), minimum flow must be raised to at least 4000 gpm (4000 to 5000 gpm), where it will remain until SDC is secured after RCS temperature rises above 230°F.
Identify when a charging pump is considered nonfunctional during pulsation dampener adjustment operations.
When a charging pump is placed in Pull-To-Lock, the pump remains functional.
However: When adjusting a charging pump pulsation dampener, that pump is isolated and therefore nonfunctional. Do not adjust more than one pulsation dampener at a time. (TLCO T3.1.102 and T3.1.103)
Describe the venting flowpath of the Pressurizer and the RDT.
While establishing a steam bubble, the pressurizer will be periodically vented through RCA-HV-103 and RCB-HV-105 to the RDT. Pressurizer level is initially raised to 90-95%. Heaters are energized and the Pressurizer is vented to the RDT.
The RDT will be vented to the Waste Gas Surge Header. CHN-HV-540 RDT Vent to Waste Gas Surge Header Isolation Valve is manually opened to maintain RDT pressure less than 25 psig.
Identify the conditions when the use of pressurizer spray must be logged.
All cycles of pressurizer main spray with fewer than four RCPs running and all cycles of auxiliary spray SHALL be logged in 40ST-9RC01, RCS and Pressurizer Heatup and Cooldown Rates.
Identify the requirements for RCP seal injection.
- Per 40OP-9RC01 Reactor Coolant Pump Operation, Seal injection is required to be supplied to the RCPs whenever RCS level is greater than 102 feet. Exceptions exist in the Outage GOP and Loss of Letdown AOP.
- Seal injection shall be in service prior to exceeding 195°F or 215 psia in the RCS in preparation for starting and running RCPs. RCS temperatures and pressures will increase as the Unit is raised to Power Operation. However, once Seal Injection has been established to running RCPs, Seal Injection may be stopped. RCS temperatures and pressure do NOT need to be lowered to re-establish Seal Injection to the running RCPs. RCPs may be operated for an indefinite period of time without Seal Injection water provided Nuclear Cooling Water is being supplied to the pumps.
- Sulzer Bingham RCP Seals are susceptible to damage if seal injection is applied while the stop seal is engaged.
Define the term “single RCP operation”.
Single RCP operation applies to:
• Individual pump operation. • Diagonally opposite pump operation for the two pump operating case.
• RCPs 1A/2A or 1B/2B.
RCP operation in any “single pump” configuration, in the 100°F to 400°F range, must be logged.
Identify the RCS temperature limits associated with RCP starts and what action must be taken if RCS heatup rates are exceeded after starting an RCP.
Reactor Coolant Pump Temperature Limitations:
• No more than two RCPs may be operated when RCS Tc is less than or equal to 200°F.
• No more than three RCPs may be operated when RCS Tc is greater than 200°F and less than or equal to 500°F.
• Heat removal via the steam generators will be limited when the plant is at low RCS temperatures, and RCS heatup rates may be exceeded if three RCPs are operated.
• If after starting the third RCP, RCS heatup rates are excessive and cannot be maintained within the limitations of LCO 3.4.3, then stop the third RCP.
Identify the consequences associated with starting RCPs when SG temperatures are greater than RCS cold leg temperature.
These limitations prevent an RCS over pressure transient that could occur if an RCP is started with the Steam Generator at a higher temperature than the RCS. In the condition of a higher temperature in the S/Gs, and given the large metal mass and water capacity of the S/Gs, they would be a heat source and cause the RCS to heat up, with the resulting expansion of the water in the RCS causing a pressure transient.
Describe when LTOPs may be isolated.
In the Mode 5 to Mode 3 procedure, LCO 3.4.13 is applicable until all RCS cold legs reach greater than 221°F. The LTOPs are isolated when RCS temperature is greater than 221°F but less than or equal to 300°F AND after SDC has been secured.
Explain the requirement maintaining the SIAS Low pressurizer pressure setpoint greater than 140 psi above the RCS saturation pressure when exceeding an RCS temperature of 485°F.
The Pressurizer Pressure — Low trip setpoint, which provides SIAS, CIAS, and RPS trip, may be manually decreased to a floor value of 100 psia to allow for a controlled cooldown and depressurization of the RCS without causing a reactor trip, CIAS, or SIAS. The margin between actual pressurizer pressure and the trip setpoint must be maintained less than or equal to the specified value (400 psia) to ensure a reactor trip, CIAS, and SIAS will occur if required during RCS cooldown and depressurization. When the RCS cold leg temperature is ≥ 485°F the setpoint must be ≥ 140 psia greater than the saturation pressure of the RCS cold leg. This is required to ensure a SIAS prior to reactor vessel upper head void formation in the event of RCS depressurization caused by a steam line break.
Identify the time limitations and guidelines for placing the turning gear in operation.
- For turning gear operation, the bearing oil header temperature from the outlet of the main turbine lube oil coolers should be between 80°F to 102°F.
- Generator seal oil shall be supplied to the main generator seals when the main turbine is on the turning gear.
- Condenser vacuum should be broken when sealing steam is lost. This will minimize damage to the labyrinth seals and limit thermal shock to the rotor shaft due to ambient air being drawn through the shaft seals.
- Turning Gear operation should be minimized in accordance with main turbine operating instructions. This will reduce copper particle generation in the field, thus minimizing the probability of field winding problems due to copper particle accumulation.
- Placing the turbine on the turning gear may be delayed until four hours before turbine startup is anticipated.
- The turbine should be on the gear for at least four (4) hours prior to rolling it with steam.
