1995 Fiscal Year Final Research Report Summary
STUDY FOR CONCENTRATION OF TECHNETIUM IN THE LOW LEVEL RADIOACTIVE LIQUID WASTE
| Project/Area Number |
06680460
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
エネルギー学一般・原子力学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
ITO Katsuo INSTITUTE FOR ADVANCED MATERIALS PROCESSING,TOHOKU UNIVERSITY,RESEARCH ASSOCIATE, 素材工学研究所, 助手 (70006047)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Low level radioactive liquid waste / Technetium / Thin layr vaporizer / Vaporizing concentration / Concentrate / Distilllate / Rhenium / Decontamination factor |
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| Research Abstract |
Reprocessing facilities for used nuclear fuels would produce the low level radioactive liquid waste containing actinides and technetium, which could not permit to discard into the environment since their activities are too high to waste. Investigator designs to recycle the concentrated liquid waste in the nuclear fuel cycling system and to dispose of them in the air-ground building. Evaporation technique is efficient for the low level radioactive liquid which does not involve the vaporizable radioactive meterials. Vaporization technique is difficult for the chemical matters of technetium compound, since technetium in the solution is easy to vaporize in the air. Firstly basic information regarding thin film evaporator was looked for, and the adequate conditions are follows : temperature : 50ﾟC,rotational speed : 600 rpm, feeding rate of sample solution : 13 ml/min, vacuum pressure : 15 mm Hg. Under these conditions the instrument could operated continuously. The solutions of tracer leve
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l of technetium were concentrated using above fixed conditions, the recovery of Tc in the concentrate was 98%, and the concentration of Tc in the distilllate was too low to determine. To get the location of 2% of Tc in the concentrating procedure, the diluted rhenium (Re) solution (100x10^<-6>g/ml) was investigated for the purpose of checking the mass balance, since chemical properties for rhenium is similar to that of technetium. The concentration of Re in the distilllate was 2x10^<-9>g/ml determined by using Inductively Coupled Plasma Mass Spectrometry, and that of concentrate was 2000x10^<-6>g/ml determined by using Inductively Coupled Plasma Atomic Emission Spectrometry. The recovery of Re was 98% which correspond to that of Tc. A decontamination factor for Re calculated from the concentration of Re both in the distilllate and feed solution was 2x10^4. The location of Re in the distilllation procedure should be studied more. Next study should be carried out for the solutions containing a salt like sodium nitrate and organic matter like dodecane. Less
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