atw - International Journal for Nuclear Power | 03.2020

atw Vol. 65 (2020) | Issue 3 ı March
RESEARCH AND INNOVATION 142
Neutronic Simulation of ALFRED Core
Using MCNPX Code
Korosh Rahbari, Darush Masti, Kamran Serpanloo and Ehsan Zarifi
Introduction Throughout history, energy has played a fundamental role in human’s progress living. To promote
nuclear power to meet the future energy needs, ten countries including Argentina, South Africa, the United States, the
United Kingdom, Brazil, Japan, Switzerland, France, Canada and Korea in a global effort (Generation IV International
Forum – GIF) have agreed to investigate the next generation of nuclear energy systems known as 4 th generation [1].
These reactors are expected to enter the market after 2030. Fundamental changes in the configuration of the systems
and the forms of the old reactors have led to the production of new reactors, which require basic research and
development, careful examination, and the construction of semi-industrial units. The capabilities of fourth-generation
reactors are seawater desalination, and thermal applications in addition to the production of electricity. In 2000, the
founding countries of GIF formed their first meeting to discuss the need for conduct research on the design of
next-generation reactors. Subsequently, a strategy was put forward to direct the activities, and the implementation
responsibility was assigned to the US Department of Energy. In this research, we investigate the neutron behavior of the
advanced reactor core with lead coolant ALFRED. The purpose of the neutron calculations of the core of a reactor is to
calculate the distribution of neutron flux in the center and to calculate the effective reproduction coefficient. Given the
necessity of performing lattice pitch neutron calculations, it is initially required to determine the real geometry of the
core, as well as the order and fuel richness, the lattice pitch the grid, the radius and height of the fuel rods, the
composition and location of the fuel absorbents, the types and locations of the control rods, the fuel complex
arrangement, and radial and axial peaking factor. The MCNPX code is used to perform neutron calculations.
This calculation is done by the MCNPX
code using the Monte Carlo statistical
method. The following six reactors
have been categorized as the 4 th
generation reactors:
1. Gas-Cooled Fast Reactor (GFR)
2. Lead-Cooled Fast Reactor (LFR)
3. Molten Salt Reactor (MSR)
4. Sodium-Cooled Fast Reactor (SFR)
5. Supercritical Water-Cooled Reactor
(SCWR)
6. Very High-Temperature Reactor
(VHTR)
LFR is one of the six advanced 4 th
generation reactors. In recent years,
this kind of reactor has attracted a lot
of attention of the world, and specially
recently countries such as Russia,
America and Germany have always
Parameter Unit Values
Thermal power MW 300
Active height cm 60
Pellet hollow diameter mm 2
Pellet radius mm 4.5
Gap thickness mm 0.15
Clad thickness mm 0.6
Pin diameter mm 10.5
Wrapper thickness mm 4
Distance between 2 wrappers mm 5
Coolant velocity m s -1 ~1.4
Lattice pitch (hexagonal) mm 13.86
Pins per FA - 127
Inner vessel radius cm 165
| Tab. 1.
Main specifications of ALFRED reactor [3].
| Fig. 1.
View of the ALFRED reactor [3].
been interested in this topic. LFR
systems have excellent material
handling capabilities due to the use of
a fast neutron spectrum, and they use
a closed fuel cycle to convert more
efficiently the enriched uranium.
It can also, as an actinide burner,
consume the spent fuel of light water
reactors (LWRs) or be used as an
adiabatic reactor (able to burn off its
produced actinide wastes).
Method and material
1 Technical description
of ALFRED reactor
As stated, the program of the ALFRED
reactor is within the framework of
the LEADER project. The purpose of
the ALFRED project is to analyze
the various aspects of lead cooling
technology in fast reactors. This
project has, therefore, a significant
role as ETDR (European Technology
Demonstrator Reactor) in the technology
chain. The ALFRED reactor
design includes a 125 MW electric
power reactor with lead coolant.
Figure 1 shows a schematic illustration
of this reactor.
Some geometric parameters of the
ALFRED reactor are shown in Table 1.
The core of this reactor has a hexagonal
grid of 171 fuel assemblies (FA),
12 control bars (CR), four safety bars
(SR) and 108 empty bars. A schematic
illustration of the core of this reactor is
shown in Figure 2.
Research and Innovation
Neutronic Simulation of ALFRED Core Using MCNPX Code ı Korosh Rahbari, Darush Masti, Kamran Serpanloo and Ehsan Zarifi