THYDE-P2

RSICC CODE PACKAGE PSR-554

1. NAME AND TITLE

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

2. CONTRIBUTORS

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.

3. CODING LANGUAGE AND COMPUTER

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

4. NATURE OF PROBLEM SOLVED

THYDE-P analyzes the behavior of LWR plants in response to various disturbances, including the thermal hydraulic transient following a break of the primary coolant pipe system, generally referred to as a loss-of-coolant-accident (LOCA). LOCA can be considered as the most critical condition for testing the methods and models for plant dynamics, since thermal hydraulic conditions in the system change drastically during the transient. THYDE-P is capable of a complete LOCA calculation from start to complete reflooding of the core by sub cooled water. The program performs steady-state adjustment, which is complete in the sense that the steady state obtained is a set of exact solutions of all the transient equations without time derivatives, not only for plant hydraulics but also for all the other phenomena in the simulation of a PWR plant.

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.

5. METHOD OF SOLUTION

In THYDE-P, a PWR plant is regarded as a network of various coolant components which may be classified into nodes and junctions. The one-dimensional mass, momentum and energy equations are suitably integrated in each node and junction. In integrating the resulting equations with respect to time, a non-linear implicit method is used on the basis of the Newton method.

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.

6. RESTRICTIONS OR LIMITATIONS

It is required that the network has at least one mixing junction except for the core heat up calculation mode and that a normal node without heat source (or sink) must be placed at both the top and bottom ends of the core. After so reticulating the plant, we have a number of nodes and junctions separately, strictly in numeric order in accordance with the following rules:

(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.

(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.

7. TYPICAL RUNNING TIME

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

8. COMPUTER HARDWARE REQUIREMENTS

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.

9. COMPUTER SOFTWARE REQUIREMENTS

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.

10. REFERENCES

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.

11. CONTENTS OF CODE PACKAGE

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.

12. DATE OF ABSTRACT

January 2010.

KEYWORDS: LOCA; THERMAL HYDRAULICS; PWR