A New Evaporation Procedure for Monitoring of Iodine-125 in Liquid Waste
1987 Volume 36 Issue 6 Pages 286-289
Details
1987 Volume 36 Issue 6 Pages 286-289
A simplified monitoring method of 125I in liquid waste was devised. The waste water of 200 cm3 was taken on a Saran (polyvinylidene chloride) film covering a stainless steel vat.A stable iodine (20 mg) and sodium hydroxide (1 mmol) was added. The water was evaporated using an infra-red lamp. After heating to dryness, the Saran film was folded and transferred into a polyethylene tube. The radioactivity of 125I was counted with a well type NaI (Tl) scintillation counter. When a multi-channel analyzer was available for counting, an absolute decay rate of 125I was calculated with single and sum photo-peak counts. The radioactivity of 125I counted by a single-channel counter must be corrected with the counting efficiency of about 55 %, with a special emphasis of a self absorption of photons.
The recovery of 125I for concentrations below the permissible level was more than 98%.
