atw 2018-04v6

inforum

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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