1. Design optimization of Toroidal Fusion blanket/shield Basic Fusion Theory The basis for fusion energy production is to collide a deuterium and a tritium nucleus so that they fuse together. The result of such an interaction produces a 14.1 MeV neutron and a 3.5 MeV α-particle. The α-particle is heavy compared to the other gases and falls out of the system. The high energy neutrons leave the system. The goal is then to slow the neutrons and have them react in wall of lithium. The following reactions then takes place in Lithium: Li 7 + n = He 4 + T + n* - 2.5 MeV Li 6 + n = He 4 + T + 4.86 MeV As shown above, when the neutron reacts with the lithium-7, more tritium (fuel) and 2.5 MeV of energy is released. This energy, along with any kinetic energy that the neutron deposits into the lithium wall, is captured in the form of heat and is used to create power in a conventional steam turbine manner. Motivation The motivation for this project arises from the desire to make the process for neutron absorption in the lithium wall as efficient as possible to maximize power output. Our goals: 1. Minimize neutron flux out of the system. 2. Maximize neutron interaction inside the lithium layer 3. Take into account physical / structural limitations Using several different MCNP models, we expect to obtain realistic results that will offer us an optimized neutron shield design that meets these criterion. MCNP Slab Model Parameters- Block Neutron Source (Red) Neutron source of 14.1 MeV neutrons for the test slab Primary Wall (Orange) Using structurally sound, inert materials, test to find a material that gives a high, lower-energy flux is present on the other side. Block blanket (Blue) The lithium layer were neutron interactions are desired to take place. We can vary the length of this up to XXX cm to maximize interactions. Shield (Grey) Outside shield with high neutron cross sections. We will vary material and thickness such that virtually no neutrons will leak out of the system. Using MCNP we aimed to first design a simple slab design. The purpose of this preliminary design is to obtain meaningful results that will translate into the toroidal geometry. These MCNP slab calculations were used to determine the following parameters inside the breeder module: vacuum wall thickness, lithium layer thickness, number and position of neutron multiplier layers. Design Process Using the following formula: A thickness for the primary wall was determined. Keeping this thickness fixed, a series of different materials were tested as slabs in MCNP. [INSERT FLUX GRAPH AROUND THESE PARTS] Future Works Upon maximizing the basic MCNP model that we have started with, we aim to modify the model to include layers of neutron multipliers in the blanket module. The goal of these layers is interact with the primary neutrons and produce more neutrons that can make fuel and energy inside the blanket. After building a model for one multiplication layer, we will determine its optimal thickness and position within the blanket module. If the addition of a multiplication layer shows that more efficiency can be gained from the lithium layer, more multiplication layers will be added and the optimal amount of multiplication material will be determined.