According to the ICRP (Publication 103), the System of Radiological Protection is based on the following three principles:
- Justification. “Any decision that alters the radiation exposure situation should do more good than harm.”
- Optimisation of Protection. “Doses should all be kept as low as reasonably achievable, taking into account economic and societal factors.” (known as ALARA or ALARP)
- Dose Limitation. “The total dose to any individual … should not exceed the appropriate limits.”
One of these principles is optimisation of protection, which requires, that:
“doses should all be kept as low as reasonably practicable”.
The term ALARP arises from UK legislation, particularly the Health and Safety at Work etc. Act 1974, which requires “Provision and maintenance of plant and systems of work that are, so far as is reasonably practicable, safe and without risks to health”. The phrase So Far As is Reasonably Practicable (SFARP) in this and similar clauses is interpreted as leading to a requirement that risks must be reduced to a level that is As Low As is Reasonably Practicable (ALARP). ALARP, used especially in the UK, is much more broad term than ALARA, since it is applicable in various fields of the regulation and management of safety-critical and safety-involved systems.
The term “as low as reasonably achievable” (ALARA) used in the optimisation principle is synonymous with ALARP, and is the term used to describe the risk reduction process outside the UK. The term ALARA, or “as low as reasonably achievable” is used interchangeably in the United States of America, almost exclusively in the field of radiation protection. ALARA and ALARP are considered to be equivalent in meaning and purpose.