Lambda-modes calculated by the Nodal Green's Function Method

Lambda(lambda)-modes are very useful for many reactor physics analysis appl ications Since modern nodal methods are known to be fast and efficient, it is suggested here - for reasons of accuracy and saving computation time - t o calculate the modes by such modern nodal techniques instead of using fini te difference methods. Because. there is a lack of a precedent, we demonstr ate here the computation and usage of modes of nodal equations by selecting the power iteration procedure with a simplified orthogonalization techniqu e to calculate the lambda-modes by the Nodal Green's Fraction Method (NGFM) . The concept of nodal adjoint equation is introduced and the NGFM adjoint equation has been solved for the first rime. At last, the physical meaning and usage of lamda-modes of nodal equations is discussed. Numerical results have demonstrated the success of this calculation procedure as rr ell as i ts excellence performance, that is accuracy, time-saving and consistency wi th results obtained by analytical and finite difference methods.