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39 Cards in this Set
- Front
- Back
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The transfer of heat from the reactor fuel pellets to the fuel cladding during normal plant operation is an example of ____________ heat transfer. A. conduction B. convection C. radiant D. two-phase
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A.
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Refer to the drawing of a fuel rod and coolant flow channel at the beginning of a fuel cycle (see figure below). Which one of the following is the primary method of heat transfer through the gap between the reactor fuel and the fuel clad? A. Conduction B. Convection C. Radiation D. Natural circulation
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A.
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During a loss-of-coolant accident, which one of the following heat transfer modes provides the most core cooling when fuel elements are not in contact with the coolant? A. Radiation B. Emission C. Convection D. Conduction
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A.
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Nuclear reactor fuel rods are normally charged with __________ gas to improve the heat transferred by __________ from the fuel pellets to the cladding. A. helium; convection B. helium; conduction C. nitrogen; convection D. nitrogen; conduction
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B.
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A nuclear power plant is operating at 60 percent power. Which one of the following is the primary method of heat transfer from the outer surface of the steam generator tubes to the bulk feedwater? A. Radiolysis B. Radiation C. Convection D. Conduction
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C.
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Which one of the following describes a heat transfer process in which convection is the most significant mode of heat transfer? A. From the reactor fuel to the core barrel during core uncovery. B. Through the tube walls in a steam generator during normal operation at 100 percent power. C. From the reactor fuel to the steam generators following a loss of all RCPs. D. From the fuel pellet centerline to the fuel clad during normal operation at 100 percent power.
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C.
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Which one of the following describes a heat transfer flow path in which conduction is the most significant mode of heat transfer? A. From the reactor fuel to the core barrel during core uncovery B. From the main turbine exhaust steam to the atmosphere via main condenser cooling water and a cooling tower during normal operation C. From the reactor fuel to the steam outlet of the steam generators during a station blackout D. From a fuel pellet to the fuel clad via the fuel rod fill gas during normal operation
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D.
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If excessive amounts of air are entrained/dissolved in the cooling water passing through a single-phase (liquid) heat exchanger, the overall heat transfer coefficient of the heat exchanger will decrease because the... A. laminar layer thickness will decrease. B. laminar layer thickness will increase. C. thermal conductivity of the cooling fluid will decrease. D. thermal conductivity of the cooling fluid will increase.
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C.
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Why is bulk boiling in the tubes of a single-phase heat exchanger undesirable? A. The bubble formation will break up the laminar layer in the heat exchanger tubes. B. The turbulence will restrict fluid flow through the heat exchanger tubes. C. The ¥T across the tubes will decrease through the heat exchanger. D. The thermal conductivity of the heat exchanger tubes will decrease.
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B.
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Which one of the following pairs of fluids undergoing heat transfer in typical cross-flow design heat exchangers will yield the greatest heat exchanger overall heat transfer coefficient? (Assume comparable heat exchanger sizes and fluid flow rates.) A. Oil to water in a lube oil cooler B. Air to water in an air compressor after-cooler C. Steam to water in a turbine exhaust steam condenser D. Water to water in a cooling water heat exchanger
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C.
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Which one of the following pairs of fluids undergoing heat transfer in typical cross-flow design heat exchangers will yield the smallest heat exchanger overall heat transfer coefficient? (Assume comparable heat exchanger sizes and fluid flow rates.) A. Oil to water in a lube oil cooler B. Air to water in an air compressor after-cooler C. Steam to water in a turbine exhaust steam condenser D. Water to water in a cooling water heat exchanger
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B.
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A nuclear power plant is operating near100 percent power. Main turbine extraction steam is being supplied to a feedwater heater. Extraction steam parameters are as follows: Steam pressure: 414 psia Steam flow rate: 7.5 x 105 lbm/hr Steam enthalpy: 1,150 Btu/lbm Assume the extraction steam condenses to a saturated liquid at 414 psia and then leaves the feedwater heater via a drain line. Assuming an ideal heat transfer process, what is the heat transfer rate from the extraction steam to the feedwater in the feedwater heater? A. 3.8 x 107 Btu/hr B. 8.6 x 107 Btu/hr C. 5.4 x 108 Btu/hr D. 7.2 x 108 Btu/hr
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C.
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A nuclear power plant was operating at a steady-state power level with the following main condenser parameters: Main condenser pressure: 1.2 psia Cooling water inlet temperature: 60EF Cooling water outlet temperature: 84EF As a result of increased condenser air inleakage, the overall heat transfer coefficient of the main condenser decreases by 25 percent. Main condenser heat transfer rate and cooling water temperatures are unchanged. Which one of the following is the approximate resulting pressure in the main condenser? A. 1.7 psia B. 2.3 psia C. 3.0 psia D. 4.6 psia
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A.
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Which one of the following pairs of fluids undergoing heat transfer in typical cross-flow design heat exchangers will yield the greatest heat exchanger overall heat transfer coefficient? (Assume comparable heat exchanger sizes and fluid flow rates.) A. Oil to water in a lube oil cooler B. Steam to water in a feedwater heater C. Water to air in a ventilation heating unit D. Water to water in a cooling water heat exchanger
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B.
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A nuclear power plant is operating near 100 percent power. Main turbine extraction steam is being supplied to a feedwater heater. Extraction steam parameters are as follows: Steam pressure: 500 psia Steam flow rate: 7.0 x 105 lbm/hr Steam enthalpy: 1,135 Btu/lbm Assume the extraction steam condenses to a saturated liquid at 500 psia and then leaves the feedwater heater via a drain line. Assuming an ideal heat transfer process, what is the heat transfer rate from the extraction steam to the feedwater in the feedwater heater? A. 3.2 x 108 Btu/hr B. 4.8 x 108 Btu/hr C. 5.3 x 108 Btu/hr D. 7.9 x 108 Btu/hr
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B.
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During steady state power operation, core thermal power can be most accurately determined by multiplying the total mass flow rate of the... A. reactor coolant by the change in temperature across the core. B. reactor coolant by the change in enthalpy in the steam generators. C. feedwater by the change in enthalpy in the steam generators. D. feedwater by the change in temperature across the core.
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C.
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A nuclear reactor is producing 200 MW of core thermal power. Reactor coolant pumps are adding 10 MW of additional thermal power into the coolant system based on heat balance calculations. The core is rated at 1,330 MW thermal power. Which one of the following is the core thermal power in percent? A. 14.0 percent B. 14.3 percent C. 15.0 percent D. 15.8 percent
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C.
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The power range nuclear instruments have been adjusted to 100 percent based on a calculated heat balance. Which one of the following would cause indicated reactor power to be greater than actual reactor power? A. The reactor coolant pump heat input term was omitted from the heat balance calculation. B. The feedwater flow rate used in the heat balance calculation was lower than actual feedwater flow rate. C. The steam pressure used in the heat balance calculation was 50 psi higher than actual steam pressure. D. The enthalpy of the feed water was miscalculated to be 10 Btu/lbm higher than actual feed water enthalpy.
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A.
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. Which one of the terms in the equation, Q= UA(T1-T2), is affected the most, and therefore most responsible for the initial increase in heat transfer rate from the reactor fuel during a minor (3 percent) steamline break? (Assume no initial change in reactor power.) A. U B. A C. T1 D. T2
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D.
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The power range nuclear instruments have been adjusted to 100 percent based on a calculated secondary heat balance. Which one of the following will result in indicated reactor power being greater than actual reactor power? A. The feedwater temperature used in the heat balance calculation was higher than actual feedwater temperature. B. The reactor coolant pump heat input term was omitted from the heat balance calculation. C. The feedwater flow rate used in the heat balance calculation was lower than actual feedwater flow rate. D. The steam pressure used in the heat balance calculation was higher than actual steam pressure.
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B.
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A nuclear reactor is operating at 80 percent power with a core ¥T of 48EF when a station blackout occurs. Natural circulation is established and core ¥T stabilizes at 40EF. If mass flow rate is 3 percent, which one of the following is the current decay heat level? A. 1 percent B. 2 percent C. 3 percent D. 4 percent
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B.
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A nuclear power plant is operating at 100 percent power with the following reactor coolant system (RCS) and steam generator (S/G) parameters: RCS average coolant temperature: 575EF RCS hot leg temperatures: 600EF RCS cold leg temperatures: 550EF S/G pressures: 885 psig The reactor is shut down and a maintenance outage is performed in which 7 percent of the tubes in each S/G are plugged. The reactor is restarted and power is ramped to 100 percent. To establish the same S/G pressure at 100 percent power, RCS average coolant temperature will have to be increased to... A. 584EF. B. 582EF. C. 580EF. D. 578EF.
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D.
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A secondary heat balance calculation is being performed at 90 percent reactor power to calibrate reactor power instrumentation. Which one of the following will result in a calculated reactor power that is less than actual reactor power? A. Steam generator pressure is indicating 20 psi above actual steam generator pressure. B. Steam generator water level is indicating 3 percent below actual steam generator water level. C. Feedwater flow rate is indicating 3 percent above actual feedwater flow rate. D. Feedwater temperature is indicating 20EF below actual feedwater temperature.
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A.
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A nuclear power plant with two steam generators (S/Gs) is operating at 90 percent power with the following S/G and reactor coolant system (RCS) parameters: RCS average coolant temperature = 575EF RCS hot leg temperatures = 600EF RCS cold leg temperatures = 550EF S/G pressures = 885 psig The reactor is shut down and a maintenance outage is performed in which multiple tubes are plugged in each S/G. The reactor is restarted with 98 percent of the RCS flow that existed prior to the outage. If RCS hot leg temperatures are maintained at 600EF at 90 percent power, the RCS cold leg temperatures will be... A. 546EF. B. 547EF. C. 548EF. D. 549EF.
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D.
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The power range nuclear instruments have been adjusted to 100 percent based on a calculated heat balance. Which one of the following will result in indicated reactor power being lower than actual reactor power? A. The feed water temperature used in the heat balance calculation was 20EF higher than actual feed water temperature. B. The reactor coolant pump heat input term was omitted from the heat balance calculation. C. The feed water flow rate used in the heat balance calculation was 10 percent higher than actual flow rate. D. The steam pressure used in the heat balance calculation was 50 psi lower than actual steam pressure.
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A.
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The power range nuclear instruments have been adjusted to 100 percent based on a heat balance calculation. Which one of the following will result in indicated reactor power being higher than actual reactor power? A. The feedwater temperature used in the heat balance calculation was 20EF higher than actual feedwater temperature. B. The reactor coolant pump heat input term was omitted from the heat balance calculation. C. The feedwater flow rate used in the heat balance calculation was 10 percent lower than actual feedwater flow rate. D. The ambient heat loss term was omitted from the heat balance calculation.
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B.
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The power range nuclear instruments have been adjusted to 100 percent based on a heat balance calculation. Which one of the following will result in indicated reactor power being lower than actual reactor power? A. The feedwater temperature used in the heat balance calculation was 20EF higher than actual feedwater temperature. B. The reactor coolant pump heat input term was omitted from the heat balance calculation. C. The feedwater flow rate used in the heat balance calculation were 10 percent higher than actual flow rates. D. The operator miscalculated the enthalpy of the steam exiting the steam generators to be 10 Btu/lbm higher than actual.
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A.
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The power range nuclear instruments have been adjusted to 100 percent based on a calculated heat balance. Which one of the following will result in indicated reactor power being lower than actual reactor power? A. The feed water temperature used in the heat balance calculation was 20EF lower than actual feed water temperature. B. The reactor coolant pump heat input term was omitted from the heat balance calculation. C. The ambient heat loss value used in the heat balance calculation was only half the actual ambient heat loss. D. The feed water flow rates used in the heat balance calculation were 10 percent higher than actual flow rates.
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C.
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The power range nuclear instruments have been adjusted to 100 percent based on a calculated heat balance. Which one of the following will result in indicated reactor power being lower than actual reactor power? A. The feedwater temperature used in the heat balance calculation was 10EF lower than actual feed water temperature. B. The reactor coolant pump heat input term was omitted from the heat balance calculation. C. The feedwater flow rate used in the heat balance calculation was 10 percent lower than actual feedwater flow rate. D. The steam pressure used in the heat balance calculation was 50 psi lower than actual steam pressure.
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C.
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The power range nuclear instruments have been adjusted to 100 percent based on a heat balance calculation. Which one of the following will result in indicated reactor power being higher than actual reactor power? A. The steam pressure used in the heat balance calculation was 50 psi higher than actual steam pressure. B. The ambient heat loss value used in the heat balance calculation was twice the actual ambient heat loss. C. The feedwater flow rate used in the heat balance calculation was 10 percent lower than actual feedwater flow rate. D. The feedwater temperature used in the heat balance calculation was 20EF higher than actual feedwater temperature.
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B.
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In a two-loop PWR nuclear power plant, indicated feedwater flow to each steam generator (S/G) is 3.3 x 106 lbm/hr at an enthalpy of 419 Btu/lbm. The steam exiting each S/G is at 800 psia with 100 percent steam quality. What is the core thermal power? (Ignoring blowdown and pump heat) A. 677 MWt B. 755 MWt C. 1,334 MWt D. 1,510 MWt
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D.
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Reactor coolant enters a nuclear reactor core at 545EF and leaves at 595EF. If the reactor coolant flow rate is 6.6 x 107 lbm/hour and the specific heat capacity of the coolant is 1.3 Btu/lbm-EF, what is the core thermal power? (1 watt = 3.4127 Btu/hour) A. 100.6 MWt B. 125.7 MWt C. 1,005.7 MWt D. 1,257.1 MWt
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D.
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A nuclear reactor is operating with the following parameters: Reactor power = 100 percent Core ¥T = 42EF Reactor coolant system flow rate = 100 percent Average coolant temperature = 587EF A station blackout occurs and natural circulation is established with the following stable parameters: Decay heat = 2 percent Core ¥T = 28EF Average coolant temperature = 572EF What is the core mass flow rate in percent? A. 2.0 percent B. 2.5 percent C. 3.0 percent D. 4.0 percent
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C.
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During a nuclear power plant outage, 5 percent of all steam generator (S/G) tubes were plugged due to wall thinning. Full-power reactor coolant system flow rate and average coolant temperature (Tave) have not changed. Given the following 100 percent power conditions before the outage: Tave = 578EF TS/G = 538EF Which one of the following will be the approximate S/G pressure when the plant is returned to 100 percent power after the outage? A. 960 psia B. 930 psia C. 900 psia D. 870 psia
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B.
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A nuclear power plant is operating with the following parameters: Reactor power: 100 percent Core ¥T: 60EF Reactor coolant system flow rate: 100 percent Average coolant temperature: 587EF A station blackout occurs and natural circulation is established with the following stable parameters: Decay heat: 1 percent Core ¥T: 30EF Average coolant temperature: 572EF What is the core mass flow rate in percent? A. 2.0 percent B. 2.5 percent C. 3.0 percent D. 4.0 percent
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A.
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During a nuclear power plant outage, 6 percent of all steam generator (S/G) tubes were plugged. Full-power reactor coolant system flow rate and average coolant temperature (Tave) have not changed. Given the following 100 percent power conditions before the outage: Tave = 584EF TS/G = 544EF Which one of the following will be the approximate S/G pressure when the plant is returned to 100 percent power after the outage? A. 974 psia B. 954 psia C. 934 psia D. 914 psia
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A.
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During a nuclear power plant outage, 5 percent of all steam generator (S/G) tubes were plugged. Full-power reactor coolant system flow rate and average coolant temperature (Tave) have not changed. Given the following 100 percent power conditions before the outage: Tave = 588.0EF TS/G = 542.0EF Which one of the following will be the approximate S/G pressure when the plant is returned to 100 percent power after the outage? A. 998 psia B. 979 psia C. 961 psia D. 944 psia
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C.
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A nuclear power plant is operating at power. Total feed water flow rate to all steam generators is 7.0 x 106 lbm/hr at a temperature of 440EF. The steam exiting the steam generators is at 1,000 psia with 100 percent steam quality. Ignoring all other heat gain and loss mechanisms, what is the reactor core thermal power? A. 1,335 MWt B. 1,359 MWt C. 1,589 MWt D. 1,612 MWt
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C.
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Two of the parameters listed below are used for calculating core thermal power using the standard heat balance method. Which one of the following identifies the two parameters? Reactor Coolant Feedwater Steam Generator Steam Generator Mass Flow Rate Temperature Pressure Water Level A. Yes No Yes No B. No Yes Yes No C. Yes No No Yes D. No Yes No Yes
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B.
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