diff --git a/2_nuclear_data.md b/2_nuclear_data.md index 60cfbbe..5be666f 100644 --- a/2_nuclear_data.md +++ b/2_nuclear_data.md @@ -269,6 +269,26 @@ Q values of fusion fuel reactions --- +## Energy of neutrons from DT fuel + +
+
+ +- A DT plasma has several fusion reactions. +- DT is the most likely reaction. +- DD and TT reactions also occur with lower probabilities. +- All reactions and emit different energy neutrons. + +
+
+ +![](images/dd_tt_dt.png) + +
+
+ +--- + ## Microscopic Cross Section
@@ -348,15 +368,52 @@ Reactions have characteristics --- -# Experimental data +## Angular distribution + +
+
+ +- The scattering angle varies depending on the energy of the incident neutron +- Low energy neutrons have isotropic scattering (even probability in all directions) +- High energy neutrons are more likely to have a low deflection angle and are forwards bias. + +
+
+ +![](images/angle_energy_cross_section.png) + +
+
+ +--- + +## Energy distribution
-Availability of experimental data varies for different reactions and different isotopes. +- There is also data on neutrons released in reactions such as (n,2n). +- The (n,2n) reaction is a threshold reaction and requires energy. +- No run away chain reaction possible. + +
+
+ +![](images/angle_energy_be9.png) + +
+
+ +--- -Typically the experimental data is then interpreted to create evaluation libraries, such as ENDF, JEFF, JENDL, CENDL. +# Experimental data +
+
+ +- Availability of experimental data varies for different reactions and different isotopes. + +- Typically the experimental data is then interpreted to create evaluation libraries, such as ENDF, JEFF, JENDL, CENDL.
@@ -383,4 +440,131 @@ There are several groups that produce and distribute nuclear data - FENDL 3.2b 🌐 191 neutron - CENDL 3.2 🇨🇳 272 neutron ---- \ No newline at end of file +--- + +# Path length + +
+
+ +- Path length = 1 / $\Sigma_{T}$ +- A 14MeV neutron will lose energy via scattering interactions +- As the neutron energy decreases the path length also decreases +- Path length at thermal energy is more constant + +![](images/neutron-scatter.png) +
+
+ +![](https://s3.amazonaws.com/media-p.slid.es/uploads/1162849/images/9184302/water_path_length.jpg) + +
+
+ + +--- + +# Energy loss + +The average logarithmic energy decrement (or loss) per collision ($\xi$) is related to the atomic mass ($A$) of the nucleus + +
+ +$\xi = 1+ \frac{(A-1)^2}{2A} ln \frac{(A-1)}{(A+1)}$ + +
+ + + + + + + + + + + + + + + + + + + + + + + + + + +
HydrogenDeuteriumBerylliumCarbonUranium
Mass of nucleus12912238
Energy decrement10.72610.20780.15890.0084
+ +--- + +## Why lithium + +
+
+ +- Lithium has a particularly high cross section for tritium production +- Li6 has a very high cross section at low neutron energies +- Li7 has a reasonable cross section at high neutron energies +- Other reaction channels are relativity low +- Often alloyed with Si or other elements to improve material properties (e.g. flammability) + +
+
+ +![](images/all_tritium_multi.png) + +* Elements up to Iron plotted +
+
+ +--- + +## Why beryllium + +
+
+ +- Beryllium has the lowest threshold energy for any isotope with a n,2n reaction. +- This means even low energy 3MeV neutrons can undergo (n,2n) reactions. +- Often alloyed with Ti or other elements to improve material properties (e.g. swelling due to retention) +- Lead is also a popular choice for a neutron multiplier + +
+
+ +![](images/all_neutron_multi.png) +* Elements up to Iron plotted + +
+
+ +--- + +## Other materials + + +## Tungsten + +- High atomic number = good gamma attenuation + +- High neutron capture resonances = good neutron attenuation + +## Water + +- High hydrogen content = excellent neutron moderator + +## Helium 4 + +- Low interaction cross sections and low density = transparent to neutrons and gammas + + +--- + +## Neutron spectra through materials + diff --git a/3_prompt_response.md b/3_prompt_response.md index 7fd1c2c..633e27d 100644 --- a/3_prompt_response.md +++ b/3_prompt_response.md @@ -94,9 +94,7 @@ style: | # Neutron wall example -TODO image of plasma -TODO image of tokamak -TODO plot of wall loading vs angle +Note to self draw tokamak with wall loading vs angle - Significant poloidal variation of neutron wall loading occur in toroidal magnetic confinement fusion reactors - Details in model behind the FW not needed for NWL calculation! @@ -112,18 +110,6 @@ TODO plot of wall loading vs angle - Total heating is used for sizing cooling systems - Nuclear energy multiplication (Mn) is ratio of energy deposited by neutrons and gamma photons in the reactor to neutron energy incident on FW -TODO making into a table -Fusion power -1GW - -Neutron power -0.8GW - -Heating deposited -1.1GW - -Neutron multiplication -1.1 --- diff --git a/4_delayed_response.md b/4_delayed_response.md index 021f53c..ce2b1b9 100644 --- a/4_delayed_response.md +++ b/4_delayed_response.md @@ -68,78 +68,31 @@ style: |
- - activation - - activity build up and decay (shark fin) - - emission spectra - - shut down dose - - waste - - decay heat vs time + - Activation + - Activity build up and decay (shark fin) + - Emission spectra + - Shut down dose + - Waste + - Decay heat vs time
- - analysis needed to lift or cool components - - activated coolant - - impact of burn up + - Analysis needed to lift or cool components + - Activated coolant + - Impact of burn up - TBR - - shielding - - pulsed irradiation / constant irradiation + - Shielding + - Pulsed irradiation / constant irradiation
--- -# Activation of materials - -Neutron induced reactions lead to unstable radioactive products. - -

https://www.w3schools.com/graphics/svg_line.asp

- - - -
- - - - - - - - - - - - - I love SVG! - - - - - - - - - - - - - -
- - - - - - ---- - -# Build up, saturation and decay - ---- - # Activation reactions + ![bg 50%](images/reaction-directions.png) ---