Toroidal Fusion Shielding Design Project Final Presentation by: Matt Franzi Andrew Stach Andrew Haefner Ian Rittersdorf

Overview Fusion Power Goals Materials Design MCNP Simulations Results and Analysis Conclusions

Fusion Power Fusing light nuclei together releases large amounts of energy D + T = He4 + n + 17.6 MeV Neutrons deposit energy in a lithium blanket Important Li Reactions 6Li + n = 4He + T + 4.86 MeV 7Li + n = 4He + T – 2.5 MeV Image courtesy of wikicommons

Goals Two primary concerns: Tritium production Tritium breeding ratio = 6Li absorption per fusion neutron Ideally keep this above unity Energy deposition in the blanket

Materials Lithium Beryllium Stainless Steel 316L Used for its tritium (fuel) production Beryllium Used for its reflective properties and (n,2n) reactions Stainless Steel 316L Used for its strength and ability to absorb neutrons

MCNP Approach Slab Model Toroidal Model Gave “ball park” figures Material thicknesses Material placements Toroidal Model Gives more realistic results

Final MCNP Model Toroidal Design ITER Size Boundaries Major Radius = 6 m Minor Radius = 2 m Height = 6 m

Model Cross-Section

Neutron Multiplication I also tend toward more boring info on formal slides but I really like how you portrayed these… try using as conclusions perhaps? N multiplication -energetic reactions from neutrons (the Be reaction that gives off a lot of E and the 4.86 MeV Li-6 reaction) Then conclude with More neutrons=more power Capitalize on (n,2n) reaction then maybe list a few materials? Neutron Multiplication More Neutrons = More Power = More $$ Find a way to produce more neutrons Layers of Neutron Multipliers Capitalize on the (n, 2n) reaction Lead Beryllium

Multiplication Layers Sheets of non-lithium material Absorbs a higher energy neutron Produces two neutrons of lower energies Is this trade off worth it? Lithum-6 reaction with thermal neutron produces 4.8 MeV

Multiplication Layer Design Symbiotic relationship between beryllium and lithium Complimentary neutron cross-sections Beryllium has 2-3 barns at energies of 2-14 MeV Lithium has 1-900 barns at energies under 2 MeV Sandwich layers of beryllium between layers of lithium Lithium acts as a high pass filter Beryllium acts as a low pass filter and creates lower energy neutrons

Multiplication Layer Model

Mutli-Layer Method Start with the analytic calcs of mean free paths for Pb and Be perhaps? Maybe refer back to the threshold energies and Q values Explain why Be was hypothesized to be the best Maybe put in our old graphic of the Pb and Be cross section

Maximization of both TBR and E/Eo pro Explain matrix and method to our madness Explain why they both sort of go hand in hand up to a point

Matrix results and graphs Explain why we are sweet

Talk about escaping particles Energy that is leaving our system Explain why we are getting the results we did (IE where and why we are depositing energy) Somewhere we should talk about all the Li-6 reactions and say that T production is the most prominent

Talk about what assumptions we made in making the reactor Talked about the tungsten here Maybe compare our ideal results to the results with varying levels of tungsten