Implementation of Advanced Multigroup Nodal and Pin Power Reconstruction Methods into PARCS 3.1 (NUREG/IA-0416)

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Publication Information

Manuscript Completed: December 2010
Date Published: May 2012

Prepared by:
Joo-il Yoon, Han Gyu Joo, Seung Hoon Ahn

A. Calvo, NRC Project Manager

Prepared as part of:
The Agreement on Research Participation and Technical Exchange
Under the Thermal-Hydraulic Code Applications and Maintenance Program (CAMP)

Published by:
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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The original multi-group solver of PARCS uses a nodal expansion method combined with onenode calculation scheme. But the neutronics solver was inefficient for application to the real-size reactor cores because of its slow performance. Moreover, the existing pin power reconstruction with the corner point balancing method does not support the multi-group structure. In order to improve the performance for multi-group problems, the semi-analytic nodal method and pin power reconstruction with the source expansion formulation have been incorporated into the PARCS code. The purpose of the nodal formulation is to solve the transverse-integrated onedimensional neutron balance equation. Also, a two-level CMFD method in which the two-group CMFD is used for accelerating the multi-group CMFD calculation has been constructed to improve the calculation efficiency. The newly implemented routines are written in the form of a static library of FORTRAN90 that forms link to the PARCS code during compilation. The new numerical method has been evaluated over benchmark problems for steady-state and transient calculations of real-size reactor core. The calculation results show an excellent agreement with the reference results of the benchmark problem. The computing time of the new routines was about 4 times shorter than that of the original routine.

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