Tadaharu Tamai

Volumetric change of simulated radioactive waste glasses irradiated by the 10B(n, α)7Li Reaction as simulation of actinide irradiation

Abstract The density change of simulated radioactive waste glasses irradiated by the 10 B(n,α) 7 Li reaction was determined by a sink-float method as a function of irradiation exposure. Simulated waste glasses P0500, P0798 and GP98/12 swelled, while P0504 shrinked. The magnitude of the density change was less than 0.6% up to a fluence of 6.6 × 10 25 reactions/m 3 , which corresponds to the cumulative irradiation during a few tens of thousand years after disposal of the waste glass from the spent fuel irradiated up to 33000 MWD/MTU. The processes which play an important role on the density change have not been clarified, but it is likely that one of the processes is helium bubble formation which was clarified by a carbon replica technique, in association with transmission electron microscopy.

Radiation effect of simulated waste glass irradiated with ion, electron and γ-ray

The density change of simulated waste glass has been measured as a function of electron fluence, using the high voltage electron microscope. A very large value of swelling 0.3, was observed. It is likely that the swelling is due to the formation of oxygen bubbles. It was observed that the swelling saturated at about 0.2 displacements per atom (dpa) and additional swelling initiated beyond 0.5 dpa. Simulated waste glass was irradiated in a nuclear reactor using the 10B(n, α)7Li reaction. The shrinking of the waste glass w observed and it saturated at about 0.2 dpa in which the value of shrinking was 0.0012. Several kinds of glass specimen were irradiated by γ-rays and density changes were measured. The glass of high silica content compacted, while waste glass of low silica content swelled by 0.0022 at 1.0 × 109 R. It can be concluded that the density change induced by γ-rays cannot be neglected, compared with the density change due to irradiation with the 10B(n, α)7Li re α-decay of actinides.

Short-lived isotopes of lanthanum, cerium and praseodymium in neutron irradiated uranium☆

Abstract The separation of fission product La, Ce and Pr was performed within 90–180 sec by electromigration. As a supporting electrolyte, the solution of nitrilotriacetic acid ([NTA] = 3·7 × 10−3M, pH = 2·0, μ ∼ 0·05) was used. Rapid location of the zone on the paper strip reached after migration was obtained by color reaction of the carrier added to the irradiated uranyl nitrate solution. The γ-ray spectrum of each element was measured by a Ge(Li) detector connected with 512 channel pulse-height analyzer. In lanthanum fraction, at early times two prominent photopeaks at 395 keV ( T 1 2 = 40 ± 2 sec ) and 541 keV ( T 1 2 = 43 ± 3 sec ) were observed. From their decay rates, we presumed that they could be attributed to 144La ( T 1 2 = 41 sec ) whose γ-ray energies have not yet been reported. The two other photopeaks at 619 and 642 keV were assigned to the 14 min 143La and 92 min 142La. In Ce fraction, the photopeaks assigned to the 3 min 145Ce and to the 14 min 146Ce were observed, while no photopeaks could definetely be assigned to the 65 sec 147Ce. Some unreported γ-rays of 145Ce were found to be 233, 300, 429 and 915 keV. In Pr fraction, the 2·0 min 148Pr (γ-ray energy = 300 keV) and 12 min 147Pr (the photopeaks at 123 and 313 keV) were identified.

Gamma-ray energies of Se-85 and Se-86

The aim of the study described was to separate Se from other flssion products rapidly by paper electrophoresis, and to measure the unknown gamma -ray energies of the short-lived Se nuclides and their relative intensities. Details are given of the experimental procedure, and results are shown tabulated. (Uk)

Rapid Separation of Fission-Product Rare Earths and Yttrium by Electromigration

The separation of fission-product La, Ce, Pr, Nd and Y was performed in 4 min by electro-migration. As complexing agent, nitrilotriacetic acid was used at two concentrations of the NTA ion selected so as to optimize mutual separation of the elements. Rapid location of the zone on the paper strip reached after migration was obtained by color reaction of the carrier added to the irradiated sample. The purity of the elements thus separated was checked by γ-ray spectrometry. At the higher concentration of NTA ([[NTA]=1.0×10−2M, pH=4.1) under which all of rare earths and Y migrate toward the anode, the elements were well separated from each other, although appreciable amounts of other F.P. were also found in each fraction. On the other hand, at the lower NTA concentration ([NTA]=4.0 × 10−3M, pH=2.0) where the F.P. all migrate toward the cathode, each zone contained the isotopes of the respective element almost exclusively, except for a few small photo-peaks attributable to other elements. In each fraction, the...

Gamma-Ray Energies and Half-Lives of Praseodymium-148 and -149

Rapid separation using NTA in paper electromigration was applied to the study of the γ-decay of 148Pr and 149Pr produced in the fission of 235U. The γ-ray spectrum was measured with a high-resolution Ge(Li) detector. The γ-transitions found to decay with half-lives shorter than 3 min were: 135, 162, 256, 300, 511, 614, 696, 868, 1,022 and 1,248 keV. Of these, the values of 300 keV, and of 135 and 162 keV were in fair agreement with those reported for 148Pr and 149Pr. The decay plot of the strong photopeak of 300 keV presented good linearity and the accurate half-life of 148Pr could be determined as 2.30±0.03 min, which is longer than the 1.98 min reported for 148Pr. Similar decay plots of both photopeaks at 135 and 162 keV gave a half-life of 2.9±0.1 min for 149Pr, which again is longer than the reported value of 2.3 min. Other low intensity photopeaks at 256, 696, 868 and 1,022 keV decaying with half-lives of 2.1∼2.4 min can possibly be attributed to 148Pr. The γ-transitions of 110, 578 and 742 keV repor...

Chemical Behavior of Carrier Free Iodine Produced by Beta-Decay and Effects of Iodine Carriers

The effect of carriers oil the chemical behavior of 131I produced from the 130Te(n, γ)13lTe 131I processes was investigated with paper electrophoresis, autoradiography and γ-ray spectrometry. If no carrier was added, the chromatograms of the iodine species revealed significant deposits of an unexpected chemical species between the spots of the iodide and iodate species. The addition of either iodate or periodate as carrier converted the species into iodate in the former case, and into iodate and periodate in the latter. Referring to the already known exchange reactions between different iodine species, hence was concluded that the species observed in the experiment without carrier was the iodite species (IO− 2), as surmised by previous authors.

Studies of focusing chromatography on its scale-up and effect of ionic strength

さきにロ紙片(2×22cm)を用いて行なう従来の分析用焦点クロマトグラフ法により,諸種放射化学的物質分離の有効な実験例を得た.本研究では,人絹用パルプ・シートを用いて大型化し,従来のものに比して多量の試料を用いた分離法を確立するため,まず金属イオンの焦点化に及ぼす基礎的因子はいかなるものかを解明することを目的とした.すなわちイオン強度,電極室のpHの変化,電位こう配,錯化剤濃度および通電時間などについて検討した.それぞれ10-3Mの銅イオン,ニッケルイオンの共存溶液より,銅イオン,ニッケルイオンの分離を行なうにあたり,トリポリリン酸ナトリウムを錯化剤として用いる場合を例にとって検討を加えた.その結果,試料溶液の帯域のイオン強度を隣接する帯域のそれに比して小にすれば分離に良好な結果を得ることができることを知った.なお錯化剤には,分離のための至適濃度が存在することが判明した.また錯化剤の濃度こう配のほかに,電位こう配,pHこう配,イオン強度のこう配などの各こう配と焦点化の問題についても知見を得ることができた.