yamc-core

Yet Another Monte Carlo: neutron and photon transport for fusion neutronics. Constructive solid and mesh geometry, coupled neutron-photon transport, CAD import, flexible tallies and transport-coupled transmutation, with the whole solver in Rust.

This is the compiled distribution, and it provides the yamc module itself, so the import name and the distribution name differ (as pillow provides PIL). Install yamc rather than this: it pins the matching version of this wheel and is where the documentation lives.

import yamc

# A point source inside a Li/Be sphere.
inner = yamc.Sphere(x0=0, y0=0, z0=0, radius=1.0)
outer = yamc.Sphere(x0=0, y0=0, z0=0, radius=200.0, boundary="vacuum")

breeder = yamc.Material(
    composition={"Li6": 0.035, "Li7": 0.465, "Be9": 0.5},
    density=2.0,
    temperature=294,
)
breeder.read_nuclear_data({
    "Be9": "tests/Be9.arrow",
    "Li6": "tests/Li6.arrow",
    "Li7": "tests/Li7.arrow",
})

void = yamc.Cell(name="void", region=inner.below)
blanket = yamc.Cell(name="blanket", region=inner.above & outer.below, material=breeder)
geometry = yamc.Geometry([void, blanket])

source = yamc.NeutronSource(
    energy=yamc.sources.fusion_neutron_spectrum(20000.0),
    position=(0, 0, 0),
)
tally = yamc.Tally(name="tbr", cells=blanket, scores=["H3-production"])

model = yamc.Model(geometry=geometry, tallies=[tally], source=source)
results = model.simulate_transport(total_particles=250_000, seed=1)
print(results[tally].mean)

Relationship to yani

yamc is a superset: it ships everything yani has (materials, decay data, irradiation schedules, inventories) plus neutron and photon transport, geometry, tallies and transport-coupled transmutation. The two are alternatives. Installing both puts two extension modules in one process, so yamc.Material and yani.Material are distinct types and the nuclear-data configuration (cross_section_data, the four transmutation_* sources) exists twice, once per package.

Pick yamc when the neutron spectrum should come from a transport solve; pick yani when you have a spectrum already and want none of the transport stack.

What it does not do

• Fixed-source transport only. No criticality or eigenvalue calculations.
• One transmutation stepper (ForwardEulerStepper, beginning-of-step rates). No predictor-corrector.
• No sensitivity or uncertainty propagation, and no pathway analysis.