Solution of mathematical adjoint equation for a higher order nodal expansion method
- Seoul National Univ. (Korea, Republic of). Dept. of Nuclear Engineering
A method for determining the mathematical adjoint solution of a higher order nodal expansion method (NEM) based on the simultaneous solution of multigroup equations for each node in the rectangular geometry is presented. In deriving the mathematical adjoint equations corresponding to these forward NEM equations, the transverse leakage terms in the WRM equations need to be replaced by partial currents. Because transverse leakage terms of a node are linked to partial currents of many neighboring nodes, replacement of transverse leakage terms by partial currents results in complicated WRM equations. Because mathematical adjoint equations are obtained by transposing the nodal forward equations, direct use of these complicated WRM equations makes the numerical computation of the adjoint solution inefficient. This problem is avoided by treating the transverse leakage terms contained in the WRM equations as additional unknowns and by including the equations defining the transverse leakage terms in terms of partial currents into the nodal forward equations. The mathematical adjoint equations are then derived by transposing the resulting nodal forward equations. This adjoint solution method is verified by comparing nodal adjoint fluxes with the fine-mesh VENTURE solution for the IAEA pressurized water reactor benchmark problem and by comparing the local reactivity changes computed with first-order perturbation theory for the IAEA PWR and the Yonggwang unit 2 PWR with the exact reactivity values determined from the eigenvalue difference between perturbed and unperturbed cores.
- OSTI ID:
- 282416
- Journal Information:
- Nuclear Science and Engineering, Vol. 123, Issue 3; Other Information: PBD: Jul 1996
- Country of Publication:
- United States
- Language:
- English
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