Putting a bunch of much more viscous radioactive material within proximity of each other is simpler than squishing and maintaining confinement of plasma under extreme conditions.
Fission reactors are relatively "easier" to simulate as giant finite element analysis Monte Carlo simulations with roughly voxels of space, i.e., thermal conductivity, heat capacity, etc. I happened to have been involved with one that was 50+ years old that worked just fine because of all of physicists and engineers who carefully crafted model data and code to reflect what would be likely to happen in reality when testing new, conventional reactor designs.
The problems with fusion are many orders-of-magnitude more involved and complex with wear, losses, and "fickleness" compared to fission.
Thus, experimental physics meeting engineering and manufacturing in new domains is expensive and hard work.
Maybe in 200 years there will be a open source, 3D-printable fusion reactor. :D
Fission reactors are relatively "easier" to simulate as giant finite element analysis Monte Carlo simulations with roughly voxels of space, i.e., thermal conductivity, heat capacity, etc. I happened to have been involved with one that was 50+ years old that worked just fine because of all of physicists and engineers who carefully crafted model data and code to reflect what would be likely to happen in reality when testing new, conventional reactor designs.
The problems with fusion are many orders-of-magnitude more involved and complex with wear, losses, and "fickleness" compared to fission.
Thus, experimental physics meeting engineering and manufacturing in new domains is expensive and hard work.
Maybe in 200 years there will be a open source, 3D-printable fusion reactor. :D