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166 Managing Global Warming

4.4 Comparison of thermophysical properties
of reactor coolants

This section is partially based on Appendix A2 from [1] and the paper by Dragunov
et al. [21].

4.4.1 Introduction
4.4.1.1 Generation II, III, and III+ reactor coolants

The current fleet of nuclear power reactors (see also, Section 4.1 and [1]) uses the
following reactor coolants:
(1) Light water (H 2 O) at subcritical pressures and temperatures (critical pressure: 22.064MPa
and critical temperature: 373.95°C)—in PWRs (single-phase cooling, i.e., liquid cooling);
BWRs (two-phase cooling, i.e., with flow boiling, outlet reactor steam quality is usually
about 10%), and LGRs (two-phase cooling, i.e., with flow boiling, outlet fuel-channel
steam quality is usually about 14% (maximum: 20%));
(2) Heavy water (D 2 O) at subcritical pressures and temperatures (critical pressure: 21.671MPa
and critical temperature: 370.7°C)—in PHWRs (single-phase cooling; however, there is a
possibility for flow boiling within some subchannels at the fuel-channel outlet, steam
quality usually does not exceed 5%);
(3) Carbon dioxide (CO 2 ) at subcritical pressures, but at supercritical temperatures (critical
pressure: 7.3773MPa and critical temperature: 30.978°C)—in an AGRs; and
(4) Liquid sodium (Na) (melting temperature: 97.7°C and boiling temperature: 882.8°C)—in
an SFR.

4.4.1.2 Generation IV reactor coolants
Generation IV nuclear reactor concepts (see also, Section 4.2 and [1]) will use the
following reactor coolants:
(1) Light water (H 2 O) at supercritical pressures and temperatures (criticalpressure - 22.064MPa
andcritical temperature: 373.95°C)—inSCWRs(single-phasecooling,because atsupercrit-
ical pressures fluids are considered single-phase substances);
(2) Helium (He) at supercritical pressures and temperatures (critical pressure: 0.2276MPa and
critical temperature: 267.95°C)—in GFRs and VHTRs;
(3) Liquid sodium (Na) (melting temperature: 97.7°C and boiling temperature: 882.8°C)—in
SFRs;
(4) Liquid lead (Pb) (melting temperature: 327.5°C and boiling temperature: 1750°C)—in
LFRs;
(5) Liquid lead-bismuth eutectic (LBE) (44.5% Pb and 55.5% Bi) (LBE: Melting temperature:
123.5°C and boiling temperature: 1670°C)—in liquid metal-cooled reactors (LMRs), for
example, in Russian SVBRs; and
(6) Molten fluoride salts (for example, FLiNaK (LiF-NaF-KF): Melting temperature: 454°C
and boiling temperature: 1570°C)—in MSRs.