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Instructions for tasks ⇐ ПредыдущаяСтр 5 из 5
RADIATION Instructions for tasks Example 1. The distance from radioactive iodine to worker is 2 m (r1), the worker obtained 0. 2 mber/week (D1). Find out obtaining dose (D2) if the distance from radioactive iodine to worker will be 3 m (r 2)? Give hygienic estimation of this dose (D2 ). Solution: You may use the formula (D — dose; r — distance).
D1 r22 F = —— = ---------- = 0. 2: D2 = 32 : 22 = 0. 2: D2 = 9: 4
D2 r ² D2 = 0. 089 mber/week Conclusion: obtaining dose = 0. 089 mber/week. This dose corresponds to hygienic standard (not more than 40 mber/week).
Example 2. Mr. R. works with a radioactive element during the 36 hours. The obtained dose of radiation is 0. 03 ber for hour. Your conclusion and recommendation about the condition of the work. Solution: 1. 0. 03 ber/hour ´ 36 hours = 1. 08 ber/week. The MPD* for week (36 hours) must be not more than 40 mber. Conclusion: He receives big dose of radiation (MPD = 40 mber/week). Recommendation: It is necessary additional preventive measures against ionizing radiation.
Example 3. Find out weekly exposuring dose of doctor who works with gamma iozining source, if the activity of this source is 5 mg. eq. rad. He works every week for 6 hours. The distance from the source is 40 cm. Solution: To find dose by the formula: 8, 4 x m x t D = ————— r2 D— dose; m — activity; t — time; r — distance.
8, 4 x 5 mg. eq. rad. x 6 hours D = ————— = 0. 157 roentgen (≈ ber) 40 cm 2 Conclusion: He receives more than normal dose of radiation (weekly MPD = 0, 04 ber = 40 mber). Recommendation: It is necessary additional preventive measures against ionizing radiation.
* MPD— Max Permissible Dose
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