RSICC CODE PACKAGE PSR-418

1. NAME AND TITLE

ORTURB: HTGR Steam Turbine Dynamic Behavior.

2. CONTRIBUTORS

Oak Ridge National Laboratory, Oak Ridge, Tennessee through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; IBM360 (P00418I036000).

4. NATURE OF PROBLEM SOLVED

ORTURB was written specifically to calculate the dynamic behavior of the Fort St. Vrain (FSV) High-Temperature Gas-Cooled Reactor (HTGR) steam turbines. The program is divided into three main parts: the driver subroutine; turbine subroutines to calculate the pressure-flow balance of the high, intermediate, and low pressure turbines; and feedwater heater subroutines.

5. METHOD OF SOLUTION

The program uses a relationship derived for ideal gas flow in an iterative fashion that minimizes computational time to determine the pressure and flow in the FSV steam turbines as a function of plant transient operating conditions. An important computer modeling characteristic, unique to FSV, is that the high-pressure turbine exhaust steam is used to drive the reactor core coolant circulators prior to entering the reheater. A feedwater heater dynamic simulation model utilizing seven state variables for each of the five heaters is included in the ORTURB computer simulation of the regenerative Rankine cycle steam turbines. The seven temperature differential equations are solved at each time-step using a matrix exponential method.

6. RESTRICTIONS OR LIMITATIONS

The turbine shaft is assumed to rotate at a constant (rated) speed of 3600 rpm. Energy and mass storage of steam in the high, intermediate, and low-pressure turbines is assumed to be negligible.

7. TYPICAL RUNNING TIME

The ORTURB turbine model uses approximately 0.05 seconds of IBM3090 CPU time for each computational time-step. This value is subject to the transient being modeled and will increase as severity of the transient increases.

8. COMPUTER HARDWARE REQUIREMENTS

540K bytes of memory are required on an IBM mainframe.

9. COMPUTER SOFTWARE REQUIREMENTS

ORTURB was developed under the following operating systems: OS/360 (IBM360); MVS (IBM3033); VM/CMS (IBM4331). A Fortran IV compiler is required.

10. REFERENCES

a) Included in documentation:

J. C. Conklin, "ORTURB: A Digital Computer Code to Determine the Dynamic Response for the Fort St. Vrain Reactor Steam Turbines," NUREG/CR-1789, ORNL/NUREG/TM-399 (March 1981).

b) Background information:

J. C. Cleveland, R. A. Hedrick, S. J. Ball, and J. G. Delene, "ORTAP: A Nuclear Steam Supply System Simulation for the Dynamic Analysis of High-Temperature Gas Cooled Reactor Transients," ORNL/NUREG/TM-78 (September 1977).

11. CONTENTS OF CODE PACKAGE

Included in the package are the referenced document in (10.a) and one DOS formatted diskette which contains the source code, input/output files and jcl to run the code. An executable is not included with the package.

12. DATE OF ABSTRACT

July 1999.

KEYWORDS: FLUID DYNAMICS; HEAT TRANSFER