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Author:Hakala, Saara Emilia
Title:Chemical decontamination of polonium-210 and americium-241 from pipe materials used in water distribution system
Publication type:Master's thesis
Publication year:2011
Pages:vi + 68 + [11]      Language:   eng
Department/School:Biotekniikan ja kemian tekniikan laitos
Main subject:Bioprosessitekniikka   (Kem-70)
Supervisor:Leisola, Matti
Instructor:Turtiainen, Tuukka
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  2063   | Archive
Keywords:decontamination
radionuclides
stainless steel
PVC
HDPE
PP
dekontaminaatio
radionuklidit
ruostumaton teräs
Abstract (eng): Radioactive substances may enter the water supply network by accident or deliberately.
They may contaminate the drinking water and attach to the pipelines.
Published data about decontamination of water distribution pipes contaminated with radionuclides has not been available to date.
In the present work adsorption of polonium-210 and americium-241 on stainless steel, polyvinyl chloride, high-density polyethylene and polypropylene vas studied.
Tri-octyl-amine, calcium acetate, EDTA, sodium bicarbonate, trisodium citrate and shock chlorination by sodium hypochlorite were tested for decontamination of radionuclides from studied materials. 75% of polonium was adsorbed on HDPE.

Stainless steel and PVC adsorbed 60% of polonium and PP 15%.
Stainless steel adsorbed americium most efficiently (65%).
Less than 50% was adsorbed on HDPE and PVC and only less than 10% adsorbed on PP.
Formation of radio colloids was observed in each reaction, but clearly most colloids were formed when experiments were performed in stainless steel and PP vessels.
The most efficient solutions for decontaminating of 210Po and 241Am from studied materials were EDTA and NaHCO3 over 99% desorption was achieved from plastics.
Materials contaminated with americium were easier to decontaminate than those contaminated with polonium.
In addition, also Ca(OAc)2 and trisodium citrate were effective decontamination solution for plastics.
Shock chlorination was inefficient method for decontamination radionuclides.
Both adsorption and desorption reaction followed pseudo second-order kinetics.
Both reactions were complete mainly in less than 24 hours.
Abstract (fin): Radioaktiivisia aineita voi päästä vedenjakeluverkostoon tahattomasti tai tahallisesti.
Ne voivat saastuttaa juomaveden ja adsorboitua putkimateriaaleihin.
Kontaminoituneet putket on mahdollista puhdistaa erilaisilla kemikaaleilla.
Tässä työssä tutkittiin polonium-210:n ja amerikium-241:n adsorptiota ruostumattomaan teräkseen, polyvinyylikloridiin, polyeteeniin sekä polypropeeniin.
Lisäksi kontaminoituneiden materiaalien puhdistamiseen kokeiltiin trioktyyliamiinia, kalsiumasetaattia, EDTA:a, natriumbikarbonaattia, trinatriumsitraattia sekä shokkikloorausta, johon käytettiin natriumhypokloriittia.

Poloniumin havaittiin adsorboituvan parhaiten polyeteeniin (75 %), toiseksi parhaiten teräkseen ja polyvinyylikloridiin (60 %) ja huonoiten polypropeeniin (15 %).
Teräs adsorboi parhaiten amerikiumia (65 %).
Polyeteeniin ja polyvinyylikloridiin amerikiumista adsorboitui alle 50 % ja polypropeeniin vain alle 10 %.
Radiokolloideja havaittiin muodostuvan kaikissa astioissa, mutta selvästi eniten niitä muodostui teräs- ja polypropeeniastioissa.
Tehokkaimmat liuokset sekä 210Po:n että 241Am:n dekontaminoimiseksi eri materiaaleista olivat EDTA ja NaHCO3, joilla saavutettiin jopa yli 99 % desorptio muoveista.
Amerikiumilla saastuneet materiaalit olivat helpompi dekontaminoida, kuin poloniumilla saastuneet.
Lisäksi muoveihin tehosivat myös Ca(OAc)2 sekä trinatriumsitraatti.
Shokkiklooraus ei ollut tehokas menetelmä radionuklidien dekontaminoimiseksi.
Sekä adsorptio- että desorptioreaktioiden havaittiin noudattavan pseudo-toisen-asteen kinetiikkaa.
Kumpikin reaktio tapahtui pääosin alle 24 tunnissa.
ED:2011-02-02
INSSI record number: 41523
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