Quiz-summary
0 of 6 questions completed
Questions:
- 1
- 2
- 3
- 4
- 5
- 6
Information
You must specify a text. |
Test your Knowledge – Reactor Dynamics
With our simple quizzes, you can test your knowledge.
It is intuitive: start quiz and answer questions.
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
Results
0 of 6 questions answered correctly
Your time:
Time has elapsed
You have reached 0 of 0 points, (0)
Categories
- Reactor Kinetics 0%
Pos. | Name | Entered on | Points | Result |
---|---|---|---|---|
Table is loading | ||||
No data available | ||||
- 1
- 2
- 3
- 4
- 5
- 6
- Answered
- Review
-
Question 1 of 6
1. Question
1 pointsPrompt neutrons are emitted directly from fission and they are emitted within:
Correct
- Prompt Neutrons. Prompt neutrons are emitted directly from fission and they are emitted within very short time of about 10-14 second.
- Delayed Neutrons. Delayed neutrons are emitted by neutron rich fission fragmentsthat are called the delayed neutron precursors. These precursors usually undergo beta decay but a small fraction of them are excited enough to undergo neutron emission. The fact the neutron is produced via this type of decay and this happens orders of magnitude later compared to the emission of the prompt neutrons, plays an extremely important role in the control of the reactor.
See: Reactor Dynamics
See: Neutrons
See: Reactivity
Incorrect
- Prompt Neutrons. Prompt neutrons are emitted directly from fission and they are emitted within very short time of about 10-14 second.
- Delayed Neutrons. Delayed neutrons are emitted by neutron rich fission fragmentsthat are called the delayed neutron precursors. These precursors usually undergo beta decay but a small fraction of them are excited enough to undergo neutron emission. The fact the neutron is produced via this type of decay and this happens orders of magnitude later compared to the emission of the prompt neutrons, plays an extremely important role in the control of the reactor.
See: Reactor Dynamics
See: Neutrons
See: Reactivity
-
Question 2 of 6
2. Question
1 pointsThe study of the time-dependence of the neutron flux, when the macroscopic cross sections are allowed to depend in turn on the neutron flux level is:
Correct
In general:
- Reactor Kinetics. Reactor kinetics is the study of the time-dependence of the neutron flux for postulated changes in the macroscopic cross sections. It is also referred to as reactor kinetics without feedbacks.
- Reactor Dynamics. Reactor dynamics is the study of the time-dependence of the neutron flux, when the macroscopic cross sections are allowed to depend in turn on the neutron flux level. It is also referred to as reactor kinetics with feedbacks and with spatial effects.
See: Reactor Dynamics
See: Neutrons
See: Reactivity
Incorrect
In general:
- Reactor Kinetics. Reactor kinetics is the study of the time-dependence of the neutron flux for postulated changes in the macroscopic cross sections. It is also referred to as reactor kinetics without feedbacks.
- Reactor Dynamics. Reactor dynamics is the study of the time-dependence of the neutron flux, when the macroscopic cross sections are allowed to depend in turn on the neutron flux level. It is also referred to as reactor kinetics with feedbacks and with spatial effects.
See: Reactor Dynamics
See: Neutrons
See: Reactivity
-
Question 3 of 6
3. Question
1 pointsTwo reactors are identical except that reactor A is near the end of core life and reactor B is near the beginning of core life. Both reactors are operating at 100 percent power when a reactor trip occurs at the same time on each reactor.
If no operator action is taken and the reactor systems for both reactors respond identically to the trip, a power level of 1.0 x 10^-5 percent will be reached first by reactor __________ because it has the __________ effective delayed neutron fraction.
-
Question 4 of 6
4. Question
1 pointsReactor operation at “zero power” (between 10E-8% – 1% of rated power) is more stable than at power operation (between 1% – 100% of rated power) – from dynamics point of view.
Correct
At minimum load, the power level does not influence the criticality (keff) of a power reactor unless thermal reactivity feedbacks act (operation of a power reactor without reactivity feedbacks is between 10E-8% – 1% of rated power). The reactor behaves as “zero power reactor”.
It is very important to pay attention to safety instructions. Since the reactor is at low power, the reactor is far from temperature feedbacks, that improves reactor stability. There is a possibility that automatic shutdown, which can be activated by reactor protection system in case too much reactivity is inserted.
The inherent power stability is ineffective below the point known as the “point of adding heat”. If a power excursion is initiated from a very low power level, power will continue to rise unchecked until the point of adding heat is reached, and the subsequent temperature rise adds negative reactivity to slow the rise of reactor power.
See: Reactor Dynamics
See: Neutrons
See: Reactivity
Incorrect
At minimum load, the power level does not influence the criticality (keff) of a power reactor unless thermal reactivity feedbacks act (operation of a power reactor without reactivity feedbacks is between 10E-8% – 1% of rated power). The reactor behaves as “zero power reactor”.
It is very important to pay attention to safety instructions. Since the reactor is at low power, the reactor is far from temperature feedbacks, that improves reactor stability. There is a possibility that automatic shutdown, which can be activated by reactor protection system in case too much reactivity is inserted.
The inherent power stability is ineffective below the point known as the “point of adding heat”. If a power excursion is initiated from a very low power level, power will continue to rise unchecked until the point of adding heat is reached, and the subsequent temperature rise adds negative reactivity to slow the rise of reactor power.
See: Reactor Dynamics
See: Neutrons
See: Reactivity
-
Question 5 of 6
5. Question
1 pointsPositive reactivity is continuously added to a critical reactor. Which one of the following values of Keff will first result in a prompt critical reactor?
-
Question 6 of 6
6. Question
1 pointsIn thermal reactors, the prompt neutron lifetime is on the order of 10−4 second.
Correct
Prompt neutron lifetime, l, is the average time from a prompt neutron emission to either its absorbtion (fission or radiative capture) or to its escape from the system. This parameter is defined in multiplying or also in nonmultiplying systems. In both systems the prompt neutron lifetimes depend strongly on:
- material composition of the system
- multiplying – nonmultiplying system
- system with or without thermalization
- isotopic composition of the system
- geometric configuration of the system
- homogeneous or heterogeneous system
- shape of entire system
- size of the system
In an infinite reactor (without escape) prompt neutron lifetime is the sum of the slowing down time and the diffusion time.
l=ts + td
In an infinite thermal reactor ts << td and therefore l ≈ td. The typical prompt neutron lifetime in thermal reactors is on the order of 10−4 second. Generally, the longer neutron lifetimes take place in systems in which the neutrons must be thermalized in order to be absorbed.
Systems in which most of the neutrons are absorbed at higher energies and the neutron thermalization is suppressed (e.g. in fast reactors), have much shorter prompt neutron lifetimes . The typical prompt neutron lifetime in fast reactors is on the order of 10−7 second.
See: Reactor Dynamics
See: Neutrons
See: Reactivity
Incorrect
Prompt neutron lifetime, l, is the average time from a prompt neutron emission to either its absorbtion (fission or radiative capture) or to its escape from the system. This parameter is defined in multiplying or also in nonmultiplying systems. In both systems the prompt neutron lifetimes depend strongly on:
- material composition of the system
- multiplying – nonmultiplying system
- system with or without thermalization
- isotopic composition of the system
- geometric configuration of the system
- homogeneous or heterogeneous system
- shape of entire system
- size of the system
In an infinite reactor (without escape) prompt neutron lifetime is the sum of the slowing down time and the diffusion time.
l=ts + td
In an infinite thermal reactor ts << td and therefore l ≈ td. The typical prompt neutron lifetime in thermal reactors is on the order of 10−4 second. Generally, the longer neutron lifetimes take place in systems in which the neutrons must be thermalized in order to be absorbed.
Systems in which most of the neutrons are absorbed at higher energies and the neutron thermalization is suppressed (e.g. in fast reactors), have much shorter prompt neutron lifetimes . The typical prompt neutron lifetime in fast reactors is on the order of 10−7 second.
See: Reactor Dynamics
See: Neutrons
See: Reactivity