**1. NAME AND TITLE**

D2O V1.0: Code System for Computing Thermodynamic and Transport Properties of D2O.

**2. CONTRIBUTOR**

Institute for Nuclear Energy, Istanbul Technical University, Maslak, Istanbul, Turkey through the OECD Nuclear Energy Agency Data Bank, Issy-les-Moulineaux, France.

**3. CODING LANGUAGE AND COMPUTER**

Fortran 77; PC (P00398PC48600).

**4. NATURE OF PROBLEM SOLVED**

D2O is a computer program for the fast computation of the thermodynamic and transport properties of heavy water (D2O) at saturation, in subcooled liquid and superheated vapor states. Specific volume (or density), specific enthalpy, specific entropy, constant-pressure specific heat and temperature at saturation are calculated by a number of piecewise continuous approximation functions of (and their derivatives are calculated with respect to) pressure whereas pressure at saturation is calculated by a piecewise continuous approximation function of temperature for heavy water. Density in subcooled liquid state, specific volume in super-heated vapor state, specific enthalpy, specific entropy and constant-pressure specific heat in both of these states are calculated by some piecewise continuous approximation functions of pressure and temperature for heavy water. The correlations used in the calculation of these thermodynamic properties of heavy water were derived by fitting some appropriate curves to the data given in the steam tables by Hill et al (1981). The whole set of correlations and the approximation method used in their derivation are presented by Durmayaz (1997). Dynamic viscosity and thermal conductivity for heavy water are calculated as functions of temperature and density with the correlations given by Hill et al (1981), by Matsunaga and Nagashima (1983) and by Kestin et al (1984). Surface tension for heavy water is calculated as a function of temperature with the correlation given by Crabtree and Siman-Tov (1993).

D2O can be used in the two-phase thermalhydraulic system analysis of the nuclear reactors that are cooled and/or moderated by heavy water because the correlations used for the thermodynamic properties in this program are functions of pressure and temperature. Temperature can also be determined by using a root finding algorithm in case pressure and enthalpy are the independent variables.

**5. METHOD OF SOLUTION**

A group of pressure-enthalpy (P-h) pairs can be given in an input data file or assigned in the main program without knowing the state in which fluid takes place. In this case, first, the enthalpies at saturation corresponding to the given pressure are computed. Second, the state is determined by comparing the given enthalpy to the saturation enthalpies. Then, the properties are computed. Program D2O can also be linked as a subroutine of another main program. In this case, any thermodynamic property at saturation can be computed directly as a function of saturation pressure as well as saturation pressure is determined directly as a function of saturation temperature. Similarly, if a P-h pair is known in subcooled liquid or superheated vapor state, any thermodynamic or transport property can be computed directly. If a ressure- temperature (P-T) pair is known in subcooled liquid or superheated vapor state, enthalpy can also be computed directly.

**6. RESTRICTIONS OR LIMITATIONS**

The range of use and the maximum error for each correlation of the thermodynamic properties of heavy water are presented by Durmayaz (1997), and are also given in the statements in the beginning of each function subprogram for each correlation.

**7. TYPICAL RUNNING TIME**

Running time depends on the number of the input P-h data pairs and the type of the FORTRAN compiler and computer used. For example, it is about 100 seconds on an IBM/PC-AT compatible 486DX2-66 and about 13 seconds on an IBM/PC-AT compatible Pentium 166 for 7487 input P-h data pairs (records).

This sample run includes the reading of the 7487 P-h data pairs from D2OINP.DAT, the fourth test input data file, which also includes the determination of the states, the computation of the thermodynamic and transport properties, the writing of the outputs (14722 records) for superheated vapor into D2OVOU.DAT file and the writing of the outputs (409 records) for saturated vapor into D2OSOU.DAT file.

**8. COMPUTER HARDWARE REQUIREMENTS**

At least an IBM/PC-AT compatible 486DX2-66 computer with 640K main memory.

**9. COMPUTER SOFTWARE REQUIREMENT**

** **The source, which is written in Fortran 77, was compiled and tested at RSICC with Lahey
F77L/EM-32 V5.2 on a Pentium running DOS6.22 and Windows95a in a MS-DOS box. The
executable is included in the distribution.

**10. REFERENCES**

**a) included in documentation:**

A. Durmayaz, "READ.ME" (April 1998).

**b) background references:**

A. Durmayaz, "Approximate Functions for the Fast Computation of the Thermo-dynamic
Properties of Heavy Water," *Nucl. Eng. and Design, 178, 309-329* (1997).

A. Crabtree, M. Siman-Tov, "Thermophysical Properties of Saturated Light and Heavy Water for Advances Neutron Source Application," ORNL/TM-12322 (May 1989).

**11. CONTENTS OF CODE PACKAGE**

Included are the document referenced in (10.a) and one diskette which includes source, test cases and an executable for the PC in a self-extracting compressed DOS file.

**12. DATE OF ABSTRACT**

April 1999.

**KEYWORD:** HEAVY WATER