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Science and Technology of Nuclear Installations
Volume 2017 (2017), Article ID 7072197, 10 pages
Research Article

Development and Application of a New High-Efficiency Sparse Linear System Solver in the Thermal-Hydraulic System Analysis Code

1Xi’an Jiaotong University, 28 W. Xianning Rd, Xi’an, China
2Science and Technology on Reactor System Design Technology Laboratory, Nuclear Power Institute of China, Chengdu, China

Correspondence should be addressed to Jianqiang Shan; nc.ude.utjx.liam@nahsqj

Received 7 April 2017; Revised 3 July 2017; Accepted 22 August 2017; Published 19 September 2017

Academic Editor: Manmohan Pandey

Copyright © 2017 Li Ge et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper presents a faster solver named NRLU (Node Reordering Lower Upper) factorization solver to improve the solution speed for the pressure equations, which are formed by RELAP5/MOD3.3. The NRLU solver uses the oriented graph method and minimal fill-ins rule to reorder the structure of the nonsymmetry sparse pressure matrix. It solves the pressure matrix by LU factorization. Then the solver is embedded into the large scale advanced thermal-hydraulic system analysis program RELAP5/MOD3.3. The comparisons of the original solver and the NRLU solver show that the NRLU solver is faster than the original solver in RELAP5/MOD3.3, and the rate enhancement can be 44.44%. The results also show that the NRLU solver can reduce the number of fill-ins effectively. This can improve the calculation speed.