47 lines
2.0 KiB
Markdown
47 lines
2.0 KiB
Markdown
---
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title: Week 4
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allDay: false
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startTime: 18:00
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endTime: 20:30
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date: 2024-09-17
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completed: null
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type: single
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---
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# Module 5.1 - Reactor Overview
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Classifying Reactors
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1. Type of reaction
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2. Moderator material
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3. Coolant
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4. Generation (I-IV)
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5. Use
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Heat is created from fission. Kinetic energy from the decay products moving around is kind of what we see as "temperature".
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# Module 5.2 - Neutron Multiplication
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## Criticality Conditions
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### Neutron Economy
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A successful reactor must
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1. Create enough excess neutrons to continue the reaction
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2. Not have so many neutrons that it becomes uncontrolled
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3. Consider material limits
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Letting too many neutrons leak is expensive. This is the gas!
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### Neutron Balance
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Rate of increase = Production - absorbed - leakage
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0 = Critical - Steady State - Static
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\> 0 Supercritical - increasing - Kinetic/Dynamic
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\< 0 Subcritical - decreasing - Kinetic/Dynamic
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### Neutron Life Cycle
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1. Birth
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2. Lifetime. Gets scattered around. Sneaky little fella
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3. Death 😬 Leaks from the system or is absorbed
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### Multiplication factor
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$$k = \frac{\text{Number of neutrons in one generation}}{\text{Number of neutrons in preceding generation}}$$
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Measures how many neutrons produced by each neutron born.
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There are more formulas in the slides. K can be based on material properties
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## Energy Dependence and Moderating
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Fission is most efficiently caused by thermal neutrons (energy < 1eV), but neutrons from fission are born at something like \>2MeV. 7 orders of magnitude reduction -- usually kinetic losses by neutrons colliding with things.
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Different neutron moderators require a different number of collisions to bring the energy down to thermal. The closer the mass is to that of a neutron, the better. Hydrogen is best, then deuterium, then beryllium, then carbon (graphite).
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# Module 5.3 - PWR and BWR Reactors
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Fuel pellots. Small boys. Stacked into fuel elements 12 feet high. about 300 per rod
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14x14 lattice or 17x17. That is one fuel assembly.
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Zirconium is used as the cladding. Low neutron absorbtion cross section.
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