atw Vol. 63 (2018) | Issue 4 ı April
that the helium-side heat transfer correlation needed to
have an appropriate Reynolds-number dependence as the
error became quite large at lower power or flow levels
neglecting this.
As aforementioned, heat exchangers are crucial for
any power plant design, especially when designing new
power plants. In addition to the heat transfer modelling
capabilities and with respect to nuclear power generation
the software has recently expanded the Generic Nuclear
Reactor model to simulate the latest nuclear reactor
designs of any geometry. Novel nuclear reactor designs
include liquid fuel reactors, liquid-metal-cooled reactors,
and high temperature gas-cooled reactors (HTGR). In
more detail, there are six reactor types that have gained
researches interest all over the world:
• Very High Temperature Reactor,
• Molten Salt Reactor,
• Sodium-Cooled Fast Reactor,
• Supercritical-Water-Cooled Reactor,
• Gas-Cooled Fast Reactor, and
• Lead-Cooled Fast Reactor.
The new “generalized fuel zone” in the GNR model that is
shown in Figure 8 is capable of handling any fuel geometry
and any fluid type. It expands the geometry capability to
plate fuel, cylindrical fuel rods, spherical fuel elements,
irregular cross-section fuel (like the four-lobe cross-shape
produced by the Lightbridge Corporation), as well as
prismatic block fuel used in some HTGRs.
Appropriate pressure drop and heat transfer correlations
can be selected from the built-in library or defined by
the user. For neutronic calculations, the generalized fuel
zone can provide temperature feedback, as well as heat
generation in all solids and in the core coolant.
The default neutronics model that is supplied with the
software is the point kinetic model which requires the
following inputs:
• Temperature feedback coefficients,
• Heat distribution map, and
• Control rod worth vs. position.
This point kinetic model is provided in a user-editable C#
script, which makes it possible to replace the point kinetic
model by linking the simulation model to an external
neutronics code. The scripted neutronics model also makes
it possible for the user to define one’s own feedback
mechanisms based on the design of the specific reactor.
| | Fig. 5.
Koeberg PWR steam generator schematic (left) [2] and simulation model (right).
| | Fig. 6.
Hamm-Uentrop THTR schematic (left) [2] and simulation model (right).
OPERATION AND NEW BUILD 219
| | Fig. 7.
Hamm-Uentrop THTR-300 steam generator comparison experiment (Exp) [3] and simulation (FNX).
Operation and New Build
Heat Transfer Systems for Novel Nuclear Power Plant Designs ı Sebastian Vlach, Christoph Fischer and Herman van Antwerpen
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