Review Questions Chapter 5 This material is provided for the sole use of students in the 2017 Winter Semester course EP4P03 Nuclear Plant Systems and Operation. This material is not to be copied or shared in either electronic or paper form.

True or False 5A.1-a Because the Steam and Feedwater systems form the normal heat sink for the energy produced by the Reactor, the reliable operation of the Steam and Feedwater systems is important for reactor safety.

True 5A.1-a Because the Steam and Feedwater systems form the normal heat sink for the energy produced by the Reactor, the reliable operation of the Steam and Feedwater systems is important for reactor safety.

True or False 5A.1-b If the turbine is not available, all the steam flow bypasses the turbine and goes directly to the condenser.

False 5A.1-b If the turbine is not available, while most of the steam by-passing the turbine will flow to the Condenser, some of the steam may be released through the Atmospheric Steam Discharge valves.

True or False 5A.2-a The steam-water mixture at the top of the steam generator tube bundle consists of about 90% steam and 10% water.

False 5A.2-a The steam-water mixture at the top of the steam generator tube bundle consists of about 10% steam and 90% water.

True or False 5A.2-b The temperature of the incoming feedwater is raised to the saturation point in the integral Preheater, and the amount of water cycling through the tube bundle and the Downcomer is typically ten times as much as feedwater entering the boiler.

True 5A.2-b The temperature of the incoming feedwater is raised to the saturation point in the integral Preheater, and the amount of water cycling through the tube bundle and the Downcomer is typically ten times as much as feedwater entering the boiler.

True or False 5A.3-a If steam pressure rises above predetermined limits, the Atmospheric and Condenser Steam Discharge Valves can be opened by the Steam Generator Pressure Control System. If steam pressure continues to rise, Safety Valves installed on top of the steam generators protect the steam system from over pressure.

True 5A.3-a If steam pressure rises above predetermined limits, the Atmospheric and Condenser Steam Discharge Valves can be opened by the Steam Generator Pressure Control System. If steam pressure continues to rise, Safety Valves installed on top of the steam generators protect the steam system from over pressure.

True or False 5A.3-b The quick closure of the Emergency Stop valves is sufficient to prevent the turbine from overspeeding.

False 5A.3-b In addition to closing the Emergency Stop Valves (which stop the steam flow to the High Pressure Turbine cylinder), it is also necessary to close the Intercept Valves leading to the Low Pressure Turbine cylinders, and to open the Release Valves, to by-pass the steam in the piping, the Separator and the Reheater, to the Condenser.

True or False 5A.4-a In the high pressure turbine the latent heat of the steam is converted to rotational energy, and in this process the moisture content of the steam increases to about 10%. The steam outlet from the HP Turbine stage passes to the Moisture Separator which removes the moisture in the steam without changing its temperature and pressure.

True 5A.4-a In the high pressure turbine the latent heat of the steam is converted to rotational energy, and in this process the moisture content of the steam increases to about 10%. The steam outlet from the HP Turbine stage passes to the Moisture Separator which removes the moisture in the steam without changing its temperature and pressure.

True or False 5A.4-b All the steam that passes through the Low Pressure Turbine is exhausted to one Condenser at approximately 5 kPa(a), 35C and 10% moisture content.

False 5A.4-b Each low pressure turbine cylinder has its own condenser, i.e. the steam from the LP turbine is exhausted to three separate condensers.

True or False 5A.5-a Atmospheric Steam Discharge Valves are opened by the steam pressure control program in proportion to the pressure error, normally with an offset of 70 kPa in the steam pressure setpoint. Under normal operating conditions the steam generator pressure will need to rise 100kPa above its setpoint before the CSDVs begin to open.

True 5A.5-a Atmospheric Steam Discharge Valves are opened by the steam pressure control program in proportion to the pressure error, normally with an offset of 70 kPa in the steam pressure setpoint. Under normal operating conditions the steam generator pressure will need to rise 100kPa above its setpoint before the CSDVs begin to open.

True or False 5A.5-b There are 12 CSDVs in a typical CANDU unit, connected in such a way that all the valves discharge steam to one condenser shell.

False 5A.5-b The 12 CSDVs are connected so that each valve discharges steam into one half of one condenser shell. (i.e. each condenser half has two CSDVs connected to it).

True or False 5A.6-a The Condensate Extraction Pump (CEP) pumps the water from the Condenser Hotwell through the Low Pressure Heaters into the Deaerator. The LP feedheaters use extraction steam from the LP turbines as their heating medium; the extraction steam condenses in the shell of the heater, and is pumped back to the condenser hotwell.

True 5A.6-a The Condensate Extraction Pump (CEP) pumps the water from the Condenser Hotwell through the Low Pressure Heaters into the Deaerator. The LP feedheaters use extraction steam from the LP turbines as their heating medium; the extraction steam condenses in the shell of the heater, and is pumped back to the condenser hotwell.

True or False 5A.6-b The feedwater system raises the temperature of the feedwater flowing from the condenser to the steam generators by heating it. This heating is done in the Low Pressure and High Pressure Heaters.

False 5A.6-b The Deaerator also adds a significant amount of heat to raise the temperature of the feedwater between the condensers and the steam generators.

True or False 5A.7-a Two 50% capacity (or three 33.3% capacity) steam generator feed pumps are required to supply the necessary flow to the steam generators above 25% full power. The steam generator feed pumps take their suction from the Deaerator Storage Tank and raise the feedwater pressure to between 4 and 7 MPa.

True 5A.7-a Two 50% capacity (or three 33.3% capacity) steam generator feed pumps are required to supply the necessary flow to the steam generators above 25% full power. The steam generator feed pumps take their suction from the Deaerator Storage Tank and raise the feedwater pressure to between 4 and 7 MPa.

True or False 5A.7-b The High Pressure Feedheaters use Extraction Steam from the High Pressure Turbine to raise the pressure of the feedwater above the pressure produced by the steam generator feed pumps.

False 5A.7-b The High Pressure Feedheaters raise the temperature of the feedwater, not is pressure.

True or False 5A.8-a Changes in the size of the steam bubbles as a function of steam generator pressure, steam and feedwater flows help to keep the measured level constant.

False 5A.8-a Changes in the size of the steam bubbles can result in significant changes in the measured (and actual) steam generator level, although the inventory of water in the steam generator remains essentially constant.

True or False 5A.8-b The steam generators are the normal heat sinks for the reactor, so in order to ensure cooling of the fuel, an adequate volume of water needs to be maintained in the steam generators. The volume of water in the steam generators is kept constant at all power levels by varying the steam generator level setpoint as a function of reactor power.

True 5A.8-b The steam generators are the normal heat sinks for the reactor, so in order to ensure cooling of the fuel, an adequate volume of water needs to be maintained in the steam generators. The volume of water in the steam generators is kept constant at all power levels by varying the steam generator level setpoint as a function of reactor power.