THORIUM AS AN ENERGY SOURCE - Opportunities for Norway ...

Thorium as an Energy Source - Opportunities for Norway
Figure 14.4: Schematic drawing of a Pressurised Heavy Water Reactor (PHWR)
or the so called CANDU reactor.
14.4 Appendix B4: Gas Cooled Reactors (GCR)
The gas-cooled reactors (GCRs) belong to the Graphite Moderated Reactor types. These reactors
use graphite as the neutron moderator and either carbon dioxide (CO2) or helium (He) gas as
coolant. The advantage of the design is that the coolant can be heated to higher temperatures
than water. As a result, higher plant efficiency (40 % or more) can be obtained compared to the
water cooled design (33 - 34 %).
The newest gas cooled reactor type is the HTGR (High Temperature Gas cooled Reactor), which is
cooled by helium and moderated by graphite. In this reactor coolant temperatures as high as
950ºC can be achieved. A Schematic drawing of an Advanced Gas Cooled Reactor (AGR) is given
in Figure 14.5.
Also belonging to the Graphite Moderated Reactor types are the Light Water cooled Gas Reactors
(LWGR). These reactors are moderated by graphite and cooled by light water.
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