Radiation damage

From Wikipedia, the free encyclopedia

For the effects of radiation of living tissues see radiation poisoning and radiation therapy

Radiation damage is a term associated with ionizing radiation.

[edit] Causes

This radiation may take several forms:

• Cosmic rays and subsequent energetic particles caused by their collision with the atmosphere and other materials.
• Radioactive daughter products (Radioisotopes) caused by the collision of cosmic rays with the atmosphere and other materials, incuding living tissues.
• Streams of energetic particles from a particle accelerator.
• Energetic particles or gamma radiation (X rays) released from collisions of such particles with a target, as in an X ray machine or incidentaly in the use of a partical accelerator.
• Particles or varyious types rays released by radioactive decay of elements, which may be naturally occurring, created by accelerator collisions, or created in a nuclear reactor and extracted for theraputic or industrial use and released accidentally, or released intentially by a dirty bomb, or accidentally by nuclear accident, or released into the atmosphere, ground, or ocean incidental to the explosion of a nuclear weapon for warfare or nuclear testing.

[edit] Effects on materials and devices

Radiation may affect materials and devices in deletorious ways:

• By causing the materials to become radioactive, and thus having the potential to cause radiation poisoning.
• By nuclear transmutation of the elements within the material and so changing its physical properties, although this is far less of importance then chemical changes.
• By breaking chemical bonds within the material, which can weaken it, cause it to swell, promote corrosion, cause imbrittlement, promote cracking or otherwise change its desirable mechanical, optical, or electronic properties.
• By causing electrical breakdown, particularly in semiconductors employed in electronic equipment, with subsequent high currents permanently damaging the devices. Devices intended for high radiation environments such as the nuclear industry and extraatmospheric (space) applications may be made radiation hard to resist such effects through design, material selection, and fabrication methods.

[edit] Countermeasures

In addition to the electronic device hardening mentioned above, some degree of protection may be obtained by shielding, usually with the interposition of high density materials (particularly lead, where space is critical, or concrete where space is available) between the radiation source and areas to be protected. For biological effects of substances such as radioactive iodine the ingestion of non-radioctive isotopes may substantially reduce the biological uptake of the radioactive form, and chelation therapy by be applied to accelerate the removal of radioactive materials formed from heavy metals from the body by natural processes.