Aveneu Park, Starling, Australia

The radiation shielding materials to cover the exterior of

The
radiation levels outside the Van Allen belts are so high that it requires
immense amounts of radiation shielding materials to cover the exterior of the
settlement. We thought of an idea that to create a magnetic field around our
settlement just like the HiVolt system so that the harmful particles from the
radiation gets attracted but it requires extra energy to run, maintaining the magnetic
shielding required, immense cost to transport materials from earth and such
strong magnetic field harming human biology so we decided to cancel this idea.

So
we came up with the idea of radiation shielding the exterior of our settlement.
The shielding we would be creating would be cheap to build and transport so
need to worry about. Most of the shielding in other settlements have very big
shielding’s making them bulky and unstable to efficiently produce pseudo
gravity. There 90% of the mass is utilized because of the bulky shielding and
keeping this mass in a stable position requires much more supervision. Our
settlement has its rotating part held with the help of a spoke which is then
attached to the main frame or central cylinder therefore our radiation
shielding would be situated at the outermost part and the inner lining would
have the capability to with stand such tension and prevent the inner
environment to change or affect.

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An
average person can handle at least 5000 milirem or 5 rad per year (1 rad = 0.01 Gy = 0.01 J/kg) and in
space the rad value would be much higher so therefore we are planning to build
a highly affordable, efficient and reasonable radiation shielding which would
be built on latest technologies present today. To provide very efficient
shielding we need to have proper and appropriate materials for that purpose.

Radiation
shielding materials differ from structure to density. Many materials are good
at shielding, absorbing the harmful particles or at reflecting the radiation
but have their own problem of low tensile strength. For an ideal radiation
shielding material it needs to have high density, high young’s modulus
(——————–), high tensile strength, low thermal conductivity and
does not produce any secondary radiation. Such a material does not exist so we
tend to combine many such materials to form a layer.

For ionizing
radiation products with high hydrogen contents are good in shielding for this
purpose we are using polythene the same materials from which plastic bags are
made. It has a low tensile strength, cannot withstand the pressure came due to
many layers of the shielding and if we are to produce it outside the earth than
it’s not possible, moon does not have those materials by which we can produce
it thus it can be protected by a layer of light and radiation protecting
material like aluminum.

For gamma
radiation we can use materials with higher density like lead, tungsten can be
used. We are using materials with higher density as its particles would have less
space between them meaning there is a high probability of getting hit by
harmful particles from the radiation and interacting with them causing it to
protect us from radiation.

Solar
radiation which consists of low intermediate protons, electrons and x ray
radiation could be stopped by using the polythene or a special type of material
called the Z-grade radiation shield which would be created from fiber metal
laminates. This technology is a flexible, lighter weight radiation shield made
from hybrid carbon/metal fabric and based on the Z-grading method of layering
metal materials of differing atomic numbers to provide radiation protection for
protons, electrons, and x-rays. To create this material, a high density metal
is plasma spray-coated to carbon fiber. Another metal with less density is then
plasma spray-coated, followed by another, and so on, until the material with
the appropriate shielding properties is formed. Resins can be added to the
material to provide structural adhesion, reducing the need for mechanical
bonding. This material is amenable to molding and could be used to build custom
radiation shielding to protect cabling and electronics in situations where
traditional metal shielding is difficult to place.

BENEFITS of
Z grade shields

·       
Flexible,
moldable, and can be made for custom, hard to-shield locations

·       
Less
weight than traditional radiation shielding for electrons and x-rays

·       

Shield can be
integrated with resins to provide easy adhesion

This is
a SEM image of Rf Plasma Spray Ta on IM7 carbon fabric.

This is
the image of titanium, tantalum, and copper carbon fiber fabrics. Laminates
can be made out of autoclave with vacuum assisted resin transfer molding
(VARTM).

 

 

 

 

On our
settlement the radiation shielding should be light as possible and so to
minimize the energy input for rotating the part as well as lowering the cost
for bringing the orbit into orbit. This encourages the use of low-density
materials, which are also beneficial because they have a high probability of
producing an atomic cross section that will interact with neutron flux,
increasing the effectiveness of the shielding. Low-density materials, however,
are as a rule worse than high-density materials at protecting from gamma radioactive
flux and high-energy beta particles. High-atomic number materials tend to be
best at protecting from these types of radiation, but they do produce secondary
radiation upon impact, which can cause greater damage to tissue than the
original radiation itself. The shielding material should be as compact and
structural as possible. Example few centimeters of lead is okay but when it
comes to 200m wide lead block it definitely creates a problem.

Our idea is
to make a layer which uses high atomic number materials in the external layers,
graduating in to lighter materials as it extends back. For example, tantalum is
often used as the outermost layer in such a shield, while other materials like
copper, steel, tin and aluminum make up the inner layers. The arrangement
chosen by NOVUS TERRA involves mostly Z grade shield and then some light
materials to absorb gamma radiation.

The layers
are as follows:-

·       
0.5
mm tantalum

·       
 0.25 mm copper

·       
 0.25 mm tin

·       
 0.5 mm low-carbon steel

·       
 25. cm titanium-magnesium alloy

·       
 20 cm Z grade shield

·       
 1.0 cm aluminum

·       
 2.0 mm polyethylene

·       
 3.0 mm aluminum

 

 

The layers graduate towards lower-Z materials as they get closer to the
inside of NOVUS TERRA, ending with a layer of aluminum to help protect the
polyethylene. The outer layers are good at stopping protons, alphas rays, and
beta rays, but produce secondary radiation in the form of gamma rays which can
be then absorbed by the inner layers. The net result of this radiation shield is
that each layer helps increase the effects of the layer before it, resulting in
up to a 60% performance boost. We have estimated that the value of rad in space
would be decreased to approximately 0.1 rad per year which is very good. For
more efficiency it may have a layer of calcium oxide or lithium hydride which
can be abundantly found on moon.

These layers would be present all around NOVUS TERRA so the people living
inside would have a much healthy life. 

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