Term
| Purpose of the flow venturi |
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Definition
| 1. The main steam line flow venturis supply a delta-P signal for measurement of the steam flow rate from each S/G. |
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Term
| Purpose of flow restrictor |
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Definition
| 2. The steam generator outlet nozzle flow restrictor is designed to limit the steam flow rate and subsequent RCS cooldown during a main steam line break accident. |
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Term
| • Purpose and Type of MSSV |
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Definition
1.1. The valves are designed to protect the integrity of the main steam piping from overpressurization.
1.2. The valves are spring opposed type valves. |
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Term
| 3. The individual lift setpoints for the SG safety valves are: |
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Definition
3.1. 1-MS-SV-101: 1085 PSIG
3.2. 1-MS-SV-102: 1095 PSIG
3.3. 1-MS-SV-103: 1110 PSIG
3.4. 1-MS-SV-104: 1120 PSIG
3.5. 1-MS-SV-105: 1135 PSIG |
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Term
| 4. The five safety valves provide each header with a cumulative relieving capacity of |
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Definition
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Term
| • How safety valve position is indicated using the Plant Computer System (PCS) |
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Definition
4. Valve position is monitored by a flow element mounted in the discharge piping of each valve.
4.1. The flow element consists of two resistive temperature detectors with a heating element connected to one of the RTDs. |
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Term
| • Purpose of the S/G PORVS |
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Definition
| 1. The SG PORVs are used to remove plant sensible heat and core residual heat (decay heat) from the RCS, and provide a means for plant cooldown when the condenser steam dumps are not available. |
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Term
| • Number of valves per main steam line |
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Definition
| 3. Each main steam header is provided with one PORV (MS PCV 101A/B/C). |
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Term
| • Normal lift setpoint of each valve |
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Definition
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Term
| • How to adjust the lift setpoint of each valve |
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Definition
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Term
| • Rated relieving capacity of each valve |
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Definition
| 425,244 lb/hr at 1025 psig |
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Term
| • How operation of the SG PORV's is affected by a loss of the Instrument Air System |
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Definition
1. Each SG PORV is provided with a backup instrument air receiver.
1.1. If instrument air system pressure decreases due to a loss of supply, excessive demand, or piping rupture, the receivers will supply air to operate the valves for an indeterminate amount of time. |
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Term
| • How valve position is detected using the Plant Computer System |
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Definition
| 2. Valve position is monitored by a flow switch mounted in the discharge of each valve. |
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Term
Explain how the position of the steam generator power-operated relief valves can be controlled from each of the following locations.
• Control room
• Auxiliary shutdown panel
• Locally in the main steam valve house |
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Definition
1. In the main control room, a manual/automatic (full-station) controller is provided for each SG PORV
2. From the Auxiliary Shutdown Panel, a manual (half-station) controller is provided for each SG PORV.
3. Locally in the main steam valve house, each SG PORV is provided with a handwheel to allow the valve to be manually overridden either open or close in the event that manual operation is required |
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Term
| • Purpose of App R switch |
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Definition
| 1.1. In order to allow overriding the control signal to the SG PORVs, a key operated instrument signal isolation switch for each valve is provided in the associated unit's cable vault. |
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Term
| • Where the keys used to operate the switches are stored for App R switches for SG PORV |
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Definition
| 2. The keys are stored in the appendix-R key locker in the control room, and also in the main key locker in the operations annex. |
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Term
| • Operation of the SG PORV in each switch position |
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Definition
3. When the switch is placed in the EMERGENCY CLOSE position, the signal to the E/P is removed causing the valve to close if open.
3.1. This effectively defeats all control input to the valve from either the control room or the auxiliary shutdown panel.
3.2. When the switch is placed in the NORMAL position, the valve will operate as required. |
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Term
| • Reactor Coolant System temperature at which steam quality is adequate for steam traps |
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Definition
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Term
| • How Reactor Coolant System heatup can be enhanced as the traps heat up |
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Definition
| 2.2. Throttling the trap bypass valve to 1 turn open as the trap heats up, will enhance RCS heatup. |
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Term
| • Purpose of the Main Steam Trip Valve |
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Definition
| 1. The purpose of the main steam trip valves is to isolate the associated steam generator in the event of a steam line rupture downstream of the trip valve. |
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Term
| • Type of valve used (Main Steam Trip Valve |
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Definition
| 2. The main steam trip valves are air-opened swing-check valves, installed backwards in the main steam piping. |
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Term
| List the actuation signals that will initiate an automatic close signal to the main steam trip valve. |
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Definition
1.1. Intermediate high-high containment pressure
1.2. High steam line flow (1/2 channels on 2/3 steam generators) coincident with low low Tavg or low steam line pressure. |
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Term
| • How the main steam trip valve is quickly closed when an automatic close signal is actuated |
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Definition
| 2. Since each valve is essentially a swing-check valve installed backwards in the piping, steam flow through the pipe assists in quick and positive closure when the valves receive a close signal during power operation. |
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Term
| • How the valve is quickly closed when an automatic close signal is actuated |
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Definition
| 1. The main steam trip valve will not open if there is excessive differential pressure across the valve. |
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Term
| Explain how a main steam trip valve is opened following a main steam isolation. |
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Definition
1.1. Instrument air pressure is available
1.2. Pressure across the valve is equalized
1.3. Automatic closure signal no longer exists
1.4. Train "A" and "B" OPEN pushbuttons on the safeguards panels are depressed (not necessary to depress them simultaneously).
1.5. Appendix-R emergency close switches in NORMAL |
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Term
| Explain the consequences of failing to return the control room Appendix-R switch to NORMAL after this switch has been used to close the main steam trip valves. |
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Definition
| 1. When the main steam trip valve appendix-R control switch is in the EMER CLOSE position and depressed, a seal-in contact keeps the valves closed after the control switch is released, as long as it is left in the EMER CLOSE position. |
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Term
| • How the valves are opened and closed using instrument air (MSTV pneumatic op) |
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Definition
1.1. The linkage connects the pistons to the rocker shaft (pivot pin) of the check valve and converts the linear motion of the pistons into rotational motion at the check valve disc.
1.2. When all the solenoid-operated valves are deenergized, instrument air is admitted to the cylinders, which causes piston motion (against spring pressure) and forces the disc to open.
1.3. The valve is closed when any one of the solenoid-operated valves is energized to bleed air from the valve actuators. |
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Term
| • Function of the rupture disc (MSTV pneumatic |
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Definition
| 2. Each air cylinder is equipped with a rupture disc to prevent damage to the operating pistons when the valve is closed rapidly (with steam flow assist). |
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Term
| • How the MSTV fails on a loss of electrical power |
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Definition
| 4. On a loss of electrical power to all of the instrument air supply solenoid-operated valves for a MSTV, the MSTV will be enabled to open. |
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Term
Explain how the position of the main steam trip valves can be controlled from each of the following locations.
• Control room (safeguards panel)
• Control room (Appendix-R switch)
• Appendix-R isolation panel |
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Definition
1. The main steam trip valves may be manually opened from the main control room safeguards panels using OPEN pushbuttons, assuming no automatic closure signal exists, and the appendix R switches on the benchboard and in the emergency switchgear room are in NORMAL.
1.1. It is not necessary to simultaneously depress both safeguards panel OPEN pushbuttons.
1.1.1. Since the solenoids de-energize to open the MSTV, they can be pushed one at a time.
1.2. The main steam trip valves may be manually closed from the main control room safeguards panels using either CLOSE pushbutton.
2. All three main steam trip valves may be manually closed simultaneously from the main control room by rotating the appendix-R switch to EMER CLOSE and then pushing it.
3. All three main steam trip valves may be manually closed simultaneously from the emergency switchgear room by rotating the appendix-R switch to EMER CLOSE. |
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Term
| List the actuation signals that will initiate an automatic close signal to the main steam trip valve bypass valves. |
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Definition
1.1. Intermediate high-high containment pressure.
1.2. High steam line flow coincident with low low Tavg or low steam line pressure. |
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Term
| Explain why steam generator pressure and main steam header pressure must be equalized before re-opening a main steam non-return valve with at least one main steam non-return valve already open |
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Definition
1.1. The sudden depressurization that would result from opening the NRV without prior equalization will result in SG swell.
1.2. SG level swell could result in high-high level turbine trip and feedwater isolation. |
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Term
| Explain why having the three main steam non-return valves all open or all closed will prevent the potential for an automatic main steam line differential pressure safety injection. |
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Definition
| 1.1. If only one NRV is open, that SG could depressurize to 100 psig less than the other two, resulting in a high steamline differential pressure SI. |
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Term
• Normal steam flow rate from each steam generator at 100% power
• Normal steam pressure of each steam generator at 0% power
• Normal steam pressure of each steam generator at 100% power |
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Definition
1. During full power operation, approximately 4.25 x 106 lbm/hr of dry, saturated steam exits each steam generator.
2. When the plant is at 0% power, steam generator pressure is maintained at approximately 1005 psig.
3. During full power operation, steam generator pressure is approximately 810 psig. |
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Term
| • Where heatup rate is monitored for MSR |
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Definition
| 1. The MSR heatup rate is monitored using MSR steam outlet computer points and the turbine Supervisory Panel recorder. |
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Term
• Instantaneous heatup rate limit
• Administrative heatup rate limit
• Overall heatup rate limit |
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Definition
2. The maximum instantaneous 50F to minimize thermal stresses on, and distortion of, the stationary LP turbine parts.
3. Reheater outlet steam temperatures (LP turbine inlet temperatures) must be closely monitored during heatup.
3.1. The administrative heat-up rate limit of 25°F in a 15-minute period MUST NOT be exceeded.
4. The rate of change of temperature at the inlet to the LP turbine is limited to 100F per hour. |
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Term
| • Required operator response if a reactor trip occurs during warmup |
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Definition
| 5. If a reactor trip occurs during MSR warmup, the turbine building operator must immediately isolate the 3-inch FCV bypass line to prevent excessive RCS cooldown. |
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Term
| • When the moisture separator reheaters are normally placed in service |
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Definition
| between 25 and 35 percent rated capacity. |
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Term
| • How the reheat steam flow control valves are rapidly closed from the control room in response to a reactor trip |
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Definition
4.2. If a reactor trip occurs, the MSR STM INLET SEL SWITCH on the reheater control panel is placed in RESET to back up the automatic closure of the MSR FCVs.
4.3. If the valves fail to close, an alternate means of closing the valves is to reduce the potentiometer to zero. |
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Term
| Explain why Health Physics must be notified when the safety, atmospheric dump, or decay heat release valves are opened. |
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Definition
| 1. Health Physics is notified when a SG safety valve, Power Operated Relief Valve (PORV), or decay heat release valve is used to bleed steam in order to ensure that any radioactive release due to steam generator primary-to-secondary leakage is monitored, calculated, and documented. |
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Term
| LOOP occurs, what will Tave stable out at and why? |
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Definition
| 551F. No steam dumps, therefore SG PORV's are maintaining |
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