The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
DEVELOPMENT OF SEALED RADIATION SOURCE BASED ON
CADMIUM-109 RADIONUCLIDE
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.NURBAEVAInstitute o f Nuclear Physics, Academy o f Sciences o f Republic o f Uzbekistan, e-mail: egamedievs(d),mail. ru
T he x -ra y fluorescent analysis is b ased o n fact th at the x-rays em itted from an io n ized atom have energies th a t are characteristic o f the elem ent involved. T he x -ray in ten sity is p ro p o rtio n al to b oth th e elem en tal concentration and the strength o f th e ionizing source. P hoton io n izatio n , w hich
The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
is achieved u sin g radioisotopes (55Fe, 57C o, 109C d ,241 A m ) is m ost convenient to nondestructive assay o f various m aterials. A m ong them the 109C d radionuclide has found w idespread u se as a p h o to n source in x -ray fluorescence analysis devices em ployed in industry fo r num erous applications such as the direct determ ination o f gold in ores, the analysis o f m etals and identification o f steels.
C adm ium -109 has a h alf-life o f 461.9 days and decays by electron capture to 109A g w ith th e em ission o f a y-ray o f 88 keV (3.79% ) along w ith th e ch aracteristic X -ray from th e K level o f A g, w ith energy o f 22.5 keV. T here are several m ethods fo r th e production o f 109C d in literature: 1) B om bardm ent o f silv er cyclotron target v ia 109A g(d,2n) 109C d reaction w ith 16 M eV deuterons. 2) B om bardm ent o f n atu ral silv er targ et v ia 109A g(p,n) 109C d reaction w ith 14 M eV p rotons. 3) P ro to n bom bardm ent o f natu ral indium target w ith 96 M eV protons. 4) Irrad iatio n o f enriched 107A g targ e t in high-flux n u clear reactor a t neutron flux 2 x 1015 n-cm ^-s'1 v ia 107A g(n,y) 108A g—>108C d (n,y) 109C d reaction. 5) Irrad iatio n o f enriched 108C d targ et in n u clear reacto r a t neutron flux lx lO 14 n-cm"2-s‘' v ia 108C d (n,y) 109C d reaction.
In the p resen t w ork w e developed both a m ethod fo r separation and p urification o f 109C d from cyclotron silv er targ et and a m ethod fo r preparation o f sealed source b ased on cadm ium -109.
T he p urification m ethod is based on th e selective adsorption o f silv er o n colum n co ntaining 0.5 g o f polyethenem onosulphide (PEM S o r trade nam e T R -1) from n itric acid solutions o f A g, C u, Z n and C d. T his sorbent has high adsorptive capacity to silver, its adsorptive capacity reach es to 1920 m g/g from 1.5 M n itric acid solutions. A fter adsorption o f silver th e so lu tio n obtained evaporated to dryness and th e solid residue is disso lv ed in 0.5 M n itric acid containing 0.1 M hydrobrom ic acid. T hen the solution obtained is p erco lated through the colum n, containing 5 m l o f D ow exl x8 resin . T he copper(II) and zinc are com pletely eluted w ith 70 m l o f 0.5 M H N 0 3 + 0 .1 M HBr. T he cadm ium -109 is eluted w ith 50 m l o f 3 M n itric acid. T he obtained solution is evaporated to dryness and the dry residue is treated by evaporation w ith 2 m l o f 12 M hydrochloric acid. A fter treatm ent the dam p residue is dissolved in 0.1 M hydrochloric acid. T he y ield o f cadm ium -109 is higher th an 90% and the radiochem ical p urity w as m ore th an 99.9% .
T he 109C d radionuclide obtained is incorporated in ceram ic m atrix m id sealed in m i argon
w elded titan iu m capsule. T he activity o f active p a rt w ith dim ensions 4 x 2 n u n w as 740 M B q. T he w indow thickness is 0.25 m m . T he testing for leakage o f the experim ental source sam ple w ith 109C d radionuclide show ed th at the activity rem oved is less 185 M Bq.
T he S cience and T echnologies C enter at C abinet o f M inisters o f R epublic o f U zbekistan support th is w ork (co n tract Xs 13-092).
