от радиации

Tritium Oxide (ENG) and 3ml of melanin solution, 1%

by V.P. Melnichenko
Director General
SC “UkrGO “Radon”
August 11, 2014


The works have been executed to check the possibility of tritium oxides dilution during the Liquid Radioactive Waste treatment with the relevant sorbents.
Sorbent processing procedure of tritium solutions

As standardized test solution, the test sample was selected from observation well No. 1 at the territory of Kyiv GMSK burial site of the State Corporation “UkrGO Radon”. Picture 1 shows the plan of Kyiv Interregional Special Combine territory with indication of the observation well No. 1 from which the sampling was taken.

Tritium Oxide (ENG) and 3ml of melanin solution, 1%

Pic. 1. Diagrammatic layout of KGMSK territory. The left part contains the location of observation wells from which the sampling of tritium concentration measurement in water as HTO.

150 ml of the sample under study was placed in retort No 1, item 2, pic. 2. Sodium thiosulphonate and soda ash was added with distillation being carried out and ignoring the first and the last distillate portions. The intermediate fraction of the distilled sample (approximately 50 ml is considered as base solution) was used for further study.

5 ml of base solution was taken to sample No. 1.1. with adding 5 ml of distilled water and 10 ml of scintillator Ultima Gold – this is considered as zero sample. 10 ml of base solution was taken to sample No 1.2. with adding 10 ml of distilled water and 1.4 g of Sorbent No 1. 10 ml of base solution was taken to sample 1.3., 10 ml of distilled water and 1 g of Sorbent No 2. 10 ml of base solution was taken to sample 1.4., 10 ml of distilled water, 1.45 g of Sorbent No 1, 1.5 g of Sorbent No 2. 10 ml of base solution was taken to sample 1.5., 10 ml of distilled water, 3 ml of one-percent solution. 4.6 ml of base solution was taken to sample 1.6., 15.4 ml of distilled water, 0.65 g of Sorbent No 1, then adding 0.85 g of Sorbent No 2 and 1 ml of one-percent solution. Samples No 1.2 – 1.6 were being mixed on a magnetic mixer for 3 hours, then about one hour were settled at room temperature to achieve the gravity sedimentation. After solution cleaning in samples No 1.2 – 1.6, they were subjected to distillation according to methodology described in the Ukrainian National Standard listed below. Scintillator was added to each of them and the tritium oxide concentration was measured. The measured data are shown in table No 1.

Beta-activity measurement of tritium water samples were carried out on liquid scintillation analyzer Tri-Carb 3100 TR/SL by Perkin Elmer Company after special samples treatment. The device concept of operation is registering the emission in the wave-length visible range that is resulted from tritium beta particles interaction with the scintillator.

The scintillator luminous intensity depends to a great degree on the measured sample purity. This requires the sample thorough cleaning from any impurity that may decrease the scintillator luminous intensity, i.e. to subdue the sample fluorescence. The impurity in the sample may be organic and nonorganic. The nonorganic impurity may be removed from the sample by its simple distillation with the fractional column or at distillation column. The organic impurity, as a rule, gets into the measured solution with the water steam. Consequently, additional chemical treatment of the initial sample is necessary. This is achieved either by as high oxidation as possible, or by organic impurity recovery in the sample.

To recover the organic impurity and its transition into nonvolatile condition during distillation a strong restorer is used – sodium thiosulfate Na2S2O3 in mildly alkaline medium createЭd by means of soda ash Na2CO3 according to methodology set forth in Ukrainian National Standard “Radiation protection “Tritium volume activity test. Method of scintillation analysis in the liquid medium (ISO 9698:1989, IDT) DSTU ISO 9698-2001”.

The primary samples were taken from the wells. Those samples, as a rule, contain high amounts of corrosion suspensions and organic components. Consequently, the selected samples were additionally treated for tritium concentration correct measurement. Equipment arrangement for water distillation to condition the samples is shown at picture 2. The selected sample was poured into retort No 1, item (2) placed on the electrical heater. To calm down cavitation when the solution (3) is boiled some pieces of ceramics (4) were placed. The steam is separated from the solution aerosol with the fractional column (5) and through Wurtz cap it goes to the uniflow condenser (9) and after steam condensation the water through the adapter goes to receiving retort No. 2 (11) where the distilled solution (12) is accumulated. From this solution the aliquot volume V1 is taken with the pipette to 20-ml vial and mixed with V2 of liquid scintillator Ultima Gold. After the sample’s strong stirring the vial is left for 20-30 minutes in dark to decrease luminescence from daylight or artificial light. Before that the surface of plastic vials was rubbed with slightly moistened gauze to remove the static electricity. The ready sample goes for measurement into analyzer Tri-Carb 3100 TR/SL. One sample measurements were carried out for 10-15 minutes with the radiometer depending on its beta-activity. After measuring the tritium activity in the aliquot volume V1 with analyzer it was measured the tritium activity in the sample solution as HTO taking into account value V1.

Tritium Oxide (ENG) and 3ml of melanin solution, 1%

Pic. 2. 1 – electrical heater, 2 – retort No 1 KH-3-250, 3 – dissolved weighed quantity, 4 – anticavitator, 5 – fractional column, 6 – glass beads, 7 – Wurtz cap, 8 – heave plug, 9 – Liebig condenser, 10 – adapter, 11 – retort No 2, KH-3-250, 12 – ready sample.

Table No 1. Tritium oxide absorption percent depending on the sorbent characteristics

Tritium Oxide (ENG) and 3ml of melanin solution, 1%

1. It was registered the effect of sample solutions activity decrease after their treatment with sorbents.
2. It is necessary to improve the structure of the sorbent active centers to increase the tritium oxide absorption percent index with sorbent in the sample.

Chief of CSRB and OOS
GK “UkrGO “Radon” V.G. Yevdokimov
Chief RL CSRB and OOS
GK “UkrGO “Radon” V.P. Stariy

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