Alara Concept: General

The Alara concept
ALARA  :  acronym for "As Low As Reasonably Achievable" means making every reasonable effort to maintain exposures to radiation or to any type of potential hazardous material presenting any kind of risk for the human health, as far below the limit(s) in this part as is practical consistent with the purpose for which the license activity is undertaken, taking into account the state of technology, the economics of improvements in relation to state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of industrial means and license materials in the public interest. It is most often used in reference to chemical or radiation exposure levels.

The Alara concept is thus valid not only for activities regarding radioactive materials, even if indeed the last decades, it has become one of the main goal to achieve in those types of activities, i.e. "nuclear world" (including energy production, radioisotopes production, medical world through all the techniques used or treatments provided to patients, ...); however, only the application of this concept to these fields will be developed in the following.

Alara is not simply a phrase, but a work principle, a mindset, a culture of professional excellence. In an ideal world, one could reduce his exposure to hazardous materials to zero, but in reality, reducing an exposure to zero is not always (let's say never) possible, at least due to the naturally occuring radioactivity that surrounds us (cosmic rays, natural radioactivity, natural isotopes in our body, etc ...).
More, certain social, technical, economic, practical, or public policy considerations will result in a small but acceptable level of risk, in other words to keep one's exposure Alara.
The risk is assumed to be linear, so as one's exposure increases, so does the risk of adverse health effects. Instead of operating at or just below permissible exposure limits, one must stay as far below the exposure limits as possible. This affords a wider margin of error should a control fail or malfunction (one's exposure level may rise but still stay below the acceptable limit).

The relation between the limits and optimization of radiation protection is described by the ICRP in publication 60 in the so-called model of the "tolerated risk". The exposure limits are the boundaries between unacceptable and tolerable. Respecting the limits guarantees the individual that he will not suffer deterministic effects, but also that the chance of developing a radiation induced cancer is small compared to other industrial and technological risks to which he is exposed. So this is tolerable from a social point-of-view.
An additional difference has to be made between a tolerable and an acceptable risk. The tolerable risk becomes acceptable when the protection is being optimized.
In its latest recommendations, the ICRP also emphasized the fact that sometimes there is an unequality in the individual dose distribution. Situations where the personnel is exposed, during work of even due to an action to reduce the risk, can lead to important dose differences. Differences being that important as to reduce them.

This means that the optimization may not only be focused on the reduction of the collective dose, but also it has to be careful for the reduction of the highest individual doses. In that way, the means of Controlling Exposure obey to the following :
1.    Three principles to remember for reducing external exposure are :
 

 

  • Time
 

 

  • Distance
 

 

  • Shielding
2.    Laboratory safety rules
3.    Labels
 

 

  • Sealed source containers must be labeled
4.    Posting
 

 

  • Caution Radioactive Materials : areas or rooms in which radioactive material is used or stored in the amount exceeding a certain times some defined limits.
 

 

  • Caution X-Rays : access to a room area where X-rays are being generated
 

 

  • Radiation Area : area accessible to individuals in which radiation levels could result in an individual receiving a dose equivalent in excess of a certain amount in a certain time, following recommendations.
 

 

  • High Radiation Area : area accessible to individuals in which radiation levels could result in an individual receiving a dose equivalent in excess of a certain amount in a certain time, following recommendations.
 

 

  • Very High Radiation Area : area accessible to individuals in which radiation levels could result in an individual receiving a dose equivalent in excess of a certain amount in a certain time, following recommendations.

No defined-upper value/level is given here above in order to stay "as general as possible", due to the fact that limits are only recommendations proposed by International Organizations or advisory groups of experts, depending on the current and applicable legislation, even if the actual propensity seems to reach "common reasonable upper limits".