Low-backed steel is the steel produced before the first atom bomb explosion in the 1940s and 1950s. With the Trinity test and the atomic bombing of Hiroshima and Nagasaki in 1945, and then subsequent nuclear weapons testing during the early years of the Cold War, the level of background radiation is increasing worldwide. Modern steel is contaminated with radionuclides because its production uses atmospheric air. Steel with a low background is so called because it does not suffer nuclear contamination. This steel is used in devices that require the highest sensitivity to detect radionuclides.
The main source of low-backed steel is a ship built before the Trinity test, the most famous of which was the German WWI war ship that mired in the Scapa Flow.
Video Low-background steel
Radionuclide contamination
From 1856 until the mid-20th century, steel was produced in a Bessemer process in which air was forced into a Bessemer converter that converted rough iron into steel. In the mid-20th century, many steel plants turned to the BOS process that uses pure oxygen instead of air. But because both processes use atmospheric gases, they are susceptible to contamination from airborne particulates. The air currently carries radionuclides, such as cobalt-60, deposited into steel to give a weak radioactive mark.
The world's anthropogenic background radiation levels peaked at 0.15 mSv/year above the natural level in 1963, the year when the Partial Nuclear Trial Ban Treaty was enacted. Since then, anthropogenic background radiation has decreased exponentially to 0.005 mSv/yr above the natural rate.
There is a radioactive cobalt-60 contamination incident as it has been recycled through the old metal supply chain.
Maps Low-background steel
Needs
Devices that require steel with a low background include:
- Geiger counter
- Medical equipment: full body count and lung count
- Scientific tools: photonic
- Aviation and outer space sensor
Because these devices detect radiation emitted from radioactive material, they require a very low radiation environment for optimal sensitivity. The low background counting room is made of low-backed steel with very heavy radiation protection. They are used to detect the smallest nuclear emissions.
References
Source of the article : Wikipedia
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