Neutron Shielding Properties of a New High-Density Concrete

The neutron shielding properties of a new high-density concrete developed in Spain have been characterized experimentally. The shielding properties of this concrete against photons were previously studied and the material is being used to build bunkers, mazes and doors in medical accelerator facilities with good overall results. In this work, the objective was to characterize the material behaviour against neutron, as well as to test alternative mixings including boron compounds in an effort to improve neutron shielding efficiency. With this purpose, different thickness were exposed to an Am-Be neutron source under controlled conditions in the neutron measurements laboratory. The original mix, which includes a high fraction of magnetite, was then modified by adding different proportions of anhydrous borax. In order to have a reference against common concrete used to shielding medical accelerator facilities, then same experiment was repeated with ordinary concrete slabs.

As far as I know, tungsten material could also be used for radiation protection. But for the information whether it could be used for neutron shielding, and how could it protect, you could visit tungsten alloy.

Radiation Exposure on Mars

The 210-day trip on Mars results in radiation exposure of the crew of 386 +/- 61 mSv. On the surface, they will be exposed to about 11 mSv per year during their excursions on the surface of Mars. This means that the settlers will be able to spend about sixty years on Mars before reaching their career limit, with respect to ESA standards. In this way, radiation protection for scientific research is very important for scientist. 

According to studying, which shows that tungsten material has a high density 65% denser than lead and 130% denser than steel, if the material goes denser, then the radiation absorption ability will be better. 

We could get the calculation from the following formula:

Formula: K = e0.693 d / △1/2

K: Shield weakened multiple

△ 1/2: The shielding material of the half-value layer values

d: Shielding thickness, with the half-value layer thickness of their units, people need to half-value layer thickness of the quality of translation into the thickness of the material, divided by the density of the material can be obtained.

For more details, you could visit: http://www.tungsten-alloy.com/tungsten-alloy-radiation-shielding.html.

Dangerous Radiation on Mars

Mars's surface receives more radiation than the Earth's but still blocks a considerable amount. Radiation exposure on the surface is 30 µSv per hour during solar minimum; during solar maximum, dosage equivalent of this exposure is reduced by the factor two.

If the settlers spend on average three hours every three days outside the habitat, their individual exposure adds up to 11 mSv per year.
The Mars One habitat will be covered by several meters of soil, which provides reliable shielding even against galactic cosmic rays. Five meters of soil provides the same protection as the Earth's atmosphere-- equivalent to 1,000 g/cm2 of shielding. With the help of a forecasting system taking shelter in the habitat can prevent radiation exposure from SPEs.

There is a studying on tungsten alloy material for radiation protection, radiation ability could be calculated basing on the following formula:

Formula: K = e0.693 d / △1/2
K: Shield weakened multiple
△ 1/2: The shielding material of the half-value layer values
d: Shielding thickness, with the half-value layer thickness of their units, people need to half-value layer thickness of the quality of translation into the thickness of the material, divided by the density of the material can be obtained.

As there is a high density for tungsten heavy alloy material, then thickness could be reduced if there is a need of the same radiation protection ability.

For more information, you could click tungsten alloy radiation protection.

Radiation Shelter for Mars Radiation

On the way to Mars, the crew will be protected from solar particles by the structure of the spacecraft. The crew will receive general protection of 10-15 gr/cm2 shielding from the structure of the Mars transit vehicle. In case of a solar flare or Solar Particle Event (SPE), this shielding will not suffice and the crew will retreat to a dedicated radiation shelter in Mars Transit habitat, taking their cue from the onboard radiation monitoring and alert system. The dedicated radiation shelter located in the hollow water tank, will provide additional shielding to the level of 40 gr/cm2. The astronauts should expect one SPE every two months on average and a total of three or four during their entire trip, with each one usually lasting not more than a couple of days.
For radiation protection, tungsten alloy material would be the most suitable material, more details, please visit tungsten alloy radiation protection.

Tungsten Radiation Protection on the Way to Mars

A study published in the journal Science in May 2013 calculates 662 +/ 108 millisieverts (mSv) of radiation exposure for a 360 day return trip, as measured by the Radiation Assessment Detector (RAD). The study shows that ninety five percent of the radiation received by the RAD instrument came from Galactic Cosmic Rays or GCRs, which are hard to shield against without use of prohibitive shielding mass (1).

The 210-day journey Mars One settlers will take, amounts to radiation exposure of 386 +/- 63 mSv, considering these recent measurements as standard. This exposure is below the upper limits of accepted standards for an astronaut career: European Space Agency, Russian Space Agency and Canadian Space Agency limit is 1000 mSv; NASA limits are between 600-1200mSv, depending on sex and age .

That is very terrible, how to have a radiation protection from that? For more details, please visit: Tungsten Alloy Radiation Shielding.

Tungsten Alloy Shielding for Radiation from Moon and Mars

Radiation protection assessments are performed for advanced lunar and Mars manned missions. The Langley cosmic ray transport code and the Langley nucleon transport code are used to quantify the transport and attenuation of galactic cosmic rays and solar proton flares through various shielding media. Galactic cosmic radiation at solar maximum and minimum conditions, as well as various flare scenarios, is considered. Then shielding thickness and shield mass estimates required to maintain incurred doses below 30-day and annual limits are determiner for simple-geometry transfer vehicles.

Tungsten alloy has very high density where it is used to radiation protection. The density for tungsten alloy is up to 65% denser than lead and 130% denser than steel. In this way, radiation could be adsorbed well compared to other material.

For more details, please visit tungsten alloy radiation shielding.

Grade for Tungsten Alloy Radiation Shielding

AMS-T-21014	Class 1	Class 1	Class 2	Class 2
Composition	90W7Ni3Fe	91W6Ni3Fe	92W5Ni3Fe	93W4Ni3Fe
Density (g/cm3)	17.1±0.15	17.25±0.15	17.50±0.15	17.60±0.15
Heat Treatment	Sintering	Sintering	Sintering	Sintering
Tensile Strength (MPa)	900-1000	900-1000	900-1100	900-1100
Elongation (%)	18-29	17-27	16-26	16-24
Hardness(HRC)	24-28	25-29	25-29	26-30

AMS-T-21014	Class 3	Class 3	Class 4
Composition	95W3Ni2Fe	96W3Ni1Fe	97W2Ni1Fe
Density (g/cm3)	18.10±0.15	18.30±0.15	18.50±0.15
Heat Treatment	Sintering	Sintering	Sintering
Tensile Strength (MPa)	920-1100	920-1100	920-1100
Elongation (%)	10-22	8-20	6-13
Hardness(HRC)	27-32	28-34	28-36

Chinatungsten can offer many tungsten alloy radiation shielding within the standard size, and also could design and manufacture a mould especially for client. Since different tungsten alloy standards have different applications, for tungsten alloy radiation shielding, usually made accordingly to AMS-T-21014.

More details, you could visit tungsten alloy standard.