≤ ξ ≤ 1,

Under 2-D cylindrical Lagrange coordinates system, multigroup time-dependent neutron and photon coupled transport equation can be defined by where 1 ∂φ g µ ∂ ∂φ g 1 ∂ + ( rφg) + ξ − ( ζφ g) + B( φg) + σ trgφ g = Qg v ∂t r ∂r ∂x r ∂ω g φg = φg ( x, r, ξ, ω, t), ( x, r) ∈ Ωxr, −