Final answer:
The safe distance for visitors of a radioactive point should be based on radiation protection principles and must limit exposure to much lower levels than occupational limits, considering intensity, time, and shielding.
Step-by-step explanation:
The distance that should be used for visitors of a radioactive point is determined by the principles of radiation protection, which include shielding, distance, and time. The primary goal is to limit exposure to radiation as much as possible to reduce the risk of harm. In light of radiation safety regulations, the distance must be sufficient to reduce the radiation exposure to visitors to a level that is significantly lower than the maximum allowable occupational doses, which range from about 20 to 50 mSv per year, depending on the country. And for the public, the exposure limits are even lower, typically 1/1000th of the occupational limit.
For example, inadvertent doses to the public from nuclear power must not exceed 0.05 mSv per year. The best practice for determining a safe distance, in this case, would consider the intensity of the radiation at the source, the time that visitors will be exposed, and the effectiveness of any potential shielding. A calculation using the inverse square law for radiation can help to determine a safe distance whereby the intensity of radiation decreases with the square of the distance from the source.