THYDE-P2: Computer Code for PWR LOCA Thermohydraulic Transient Analysis

Department of Nuclear Safety Evaluation Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki-Ken, Japan, through the OECD NEA Data Bank, Issy-les-Moulineaux, France.

FACOM VP-100; Fortran 77 (P00554FV10000). (NEADB ID: NEA-0779/02)

THYDE-P2 contains among others the following improvements over THYDE-P1:[*] (1) not only the mass and momentum equations but also the energy equation are included in the non-linear implicit scheme; (2) the valve model is implemented; (3) the relaxation equation for void fraction is theoretically derived; (4) vectorized programming is implemented; (5) both EM (evaluation mode) and BE (best estimate) calculations are possible.

The Jacobian matrix of the basic equations can be reduced to a simple form by the network theory, which is one of the characteristics of THYDE-P. To solve the basic equations by the non-linear implicit method, various smoothing functions with respect to time are introduced for mode changes such as phase change and flow reversal. New models for a steam generator and a pressurizer are implemented.

A THYDE-P calculation is started by a steady-state adjustment, where the basic equations are exactly solved without time derivatives. THYDE-P is able to calculate through both blow-down and refill-reflood phases without any change of models and physical conditions of the coolant. A model which takes non-equilibrium effects into account is newly implemented.

(a) Normal nodes (except linkage nodes) should be numbered in numerical order chain-wise from one mixing junction to another according to the direction of the steady-state chain flow.

(b) Then linkage nodes should be numbered in numeric order chain-wise from the corresponding mixing junction.

(c) Special nodes should be numbered after all the normal and linkage nodes.

(d) Among junctions, normal and guillotine break junctions should be numbered first. Then the mixing junctions should be numbered according to the direction of the steady-state flow. After these, the injection junctions and finally the dead-end junctions should be numbered.

(e) In the present version of THYDE-P, it is required that either of the hot leg nodes adjacent to the upper plenum mixing junction must be numbered as one and that the upper plenum should be numbered first among the mixing junctions.

The THYDE-P sample problem with 101 time steps required 76 seconds of CPU time on the IBM 3081.

The code was developed on a FACOM VP-100 and was tested on an IBM 3090. Storage requirement for the test case on an IBM 3090 computer is 1840K bytes.

A Fortran compiler is required on all systems. No executables are included in the package. The code was developed on mainframe computers and has not been ported to Unix or Windows operating systems. The NEADB first released THYDE-P2 in 1989; it was not tested or modified when it was released by RSICC in 2009.

Y. ASAHI *et al.* *THYDE-P2:
RCS (Reactor Coolant System) Analysis Code*, JAERI-1300, (December 1986)
Japan Atomic Energy Research Institute report.

T. Shimizu and Y. Asahi, *A
Through Calculation of 1,100 MWe PWR Large Break LOCA by THYDE-P (Sample Calculation
Run 20),* JAERI M 9819 (November 1981) Japan Atomic Energy Research
Institute report.

M. Hirano, *Through Analysis
of LOFT L2-3 by THYDE-P Code (Sample Calculation Run 40)*, JAERI-M 9765 (October
1981) Japan Atomic Energy Research Institute report.

M. Hirano and Y. Asahi, *Through
Analysis of LOFT L2-2 by THYDE-P Code (I) (Sample Calculation Run 30)*, JAERI-M
9535 (June 1981) Japan Atomic Energy Research Institute report.

M. Hirano, T. Shimizu and Y. Asahi,
*Analysis of LOFT Small Break Experiment L3-1 with THYDE-P Code (CSNI International
Standard Problem No. 9 and THYDE-P Sample Calculation Run 50)*, JAERI-M 82-008
(February 1982) Japan Atomic Energy Research Institute report.

The package contains referenced documents cited in Section 10 and a self-extracting compressed DOS file on one CD Rom. This file contains Fortran source code, steam table and sample problem input and output.

January 2010.

KEYWORDS: LOCA; THERMAL HYDRAULICS; PWR