Determination of radioisotopes of Ce,Eu, Pu,Am and Cm in low-level-wastes from power reactors

Long-lived isotopes of lanthanides and actinides are very important for the disposal of low-level radioactive wastes. These nuclides serve for risk calculations of accidents. Their determination requires radiochemical separation from high activity main nuclides. Supervision of waste vessels is done by direct non-destructive -spectrometry of the key nuclides:⁶⁰Co for corrosion products and¹³⁷Cs as for fission products as for transuranic elements. The activity ratios of the long-lived nuclides to the key nuclides are called scaling factors. They have to be determined radiochemically in the laboratory in representative samples of each waste type. They are used for activity calculations of long-lived nuclides in the waste vessels. The scaling factors determined are of the order of magnitude of 10^–6 and due to the fact that we have used low-level measurement techniques, we could performe the necessary chemical separations in a laboratory not exceeding the 10-fold free-level limit.     

The production of no carrier added arsenic radioisotopes in nuclear reactors

The comparative advantages and drawbacks of some reactor-produced arsenic radioisotopes having favourable characteristics for their use as tracers are discussed. The study comprises their preparation based on: (a) capture reactions on germanium; (b) threshold reactions on germanium, selenium and bromine; (c) secondary reactions on germanium, induced by recoil protons and tritons produced by the action of neutrons on lithium. The recommended options for the production of relatively short half-life radionuclides are ⁷⁷As by capture on germanium or ⁷⁶As via (n,α) reaction on bromine, while two different ways are applicable for the production of ⁷⁴As, longer-lived radioisotope.

     

Estimating the activity of radioisotopes produced in intermittent irradiation of targets in nuclear reactors

This paper presents a rapid and reasonably accurate mathematical solution to the estimation of radioisotopes produced by the intermittent neutron irradiation of targets in nuclear reactors including the points in time of attaining maximum activities for stopping the nuclear reaction for chemical processing. The formulae used in these estimations are presented.     

Scaling factors for activated corrosion products in low-level-wastes from power reactors

Long-lived isotopes of corrosion products are very important for the disposal of low-level radioactive wastes. These nuclides serve for risk calculations of accidents. Their determination needs the radiochemical separation from high active main nuclides. Supervision of waste vessels is done by direct non-destructive -spectrometry of the key nuclide⁶⁰Co for corrosion products. The activity ratios of the long-lived nuclides to the key nuclides are called scaling factors. We have determined such factors radiochemically in evaporation residues of power water and cooling water. They are used for activity calculations of long-lived nuclides in the waste vessels. In case of⁵⁹Ni the obtained scaling factor was compared with a literature value and values calculated on the basis of nuclear data. Our value was in a good agreement with the calculated one. Due to the fact, that we have used low-level measurement techniques, we could perform the necessary chemical separations in a laboratory not exceeding the 10-fold free-level limit.     

Determination of strontium radioisotopes in soils

Summary A method is proposed for determination of radiostrontium in soils which is based on selective strontium separation by liquid-liquid extraction with dicyclohexano-18-crown-6 in chloroform, loading of the extract on a thin-layer plate and TLC separation of strontium and yttrium radioisotopes using a circular procedure. The method allows the separate determination of ⁸⁹Sr and ⁹⁰Sr. The strontium chemical yield is more than 90%, the detection limit is about 0.5 Bk/g, RSD is equal to 2–5%.     

Supply and waste management of radioisotopes in Japan

Radioisotopes have been widely used in Japan. The total number of facilities working with radioisotopes or radiation instruments reached to 5,509 in 1993. The state of supply of radioisotopes and management of radioactive wastes generated from the use of radioisotopes is described.     

Determination of the129I content of the primary coolant of nuclear power reactors

A neutron activation determination of the content of¹²⁹I in the cooling water of nuclear power reactors is described.¹²⁹I is coprecipitated as PbI₂. After neutron irradiation the gamma-spectrum of PbI₂ is measured. The detection limit for¹²⁹I is 2.9 mBq/dm³. The applicability of X-ray spectrometry for¹²⁹I determination is also evaluated. The proposed methods are applied for determination of the¹²⁹I content of the cooling water of WWR-440 type reactors at the nuclear power station Kozloduy, Bulgaria     

Application of radioisotopes in the field of nuclear medicine

A comprehensive review has been made to discuss the role of various radionuclides of lanthanide series elements in the field of nuclear medicine. The role of several pharmaceuticals labeled with radiolanthanides and used for investigative purposes like measurement of cerebral blood flow, bone density measurement, bone marrow imaging, etc., have been described. The role of lanthanide radionuclides in radiation synovectomy, radioimmunotherapy, etc., have also been discussed. Methods of preparation of some representative radiopharmaceuticals like¹⁵³Sm-EDTMP,¹⁵³Sm-HYP, have been presented. An outline on the production of carrier free radioisotopes of lanthanide series elements has been given.     

Cyclotron production of radioisotopes for use in nuclear medicine

Preparation of a number of cyclotron produced short lived radiopharmaceuticals labelled with¹¹C,¹⁸F,¹³N,¹²³I and⁸¹Rb/⁸¹Kr are described.     

Chemistry in microstructured reactors

The application of microstructured reactors in the chemical process industry has gained significant importance in recent years. Companies that offer not only microstructured reactors, but also entire chemical process plants and services relating to them, are already in existence. In addition, many institutes and universities are active within this field, and process-engineering-oriented reviews and a specialized book are available. Microstructured systems can be applied with particular success in the investigation of highly exothermic and fast reactions. Often the presence of temperature-induced side reactions can be significantly reduced through isothermal operations. Although microstructured reaction techniques have been shown to optimize many synthetic procedures, they have not yet received the attention they deserve in organic chemistry. For this reason, this Review aims to address this by providing an overview of the chemistry in microstructured reactors, grouped into liquid-phase, gas-phase, and gas-liquid reactions.     

Dry-distillation of experimental animal wastes containing radioisotopes

Mice were dry-distilled at 800 degrees C for 10 min, after [32P]orthophosphate or L-[4,5-3H]leucine was intraperitoneally administered. Phosphorus-32 was quantitatively recovered in the residual solid, whereas 95% of 3H was found int he distillate (condensed water). When 14C (L-[U-14C]malic acid or L-[U-14C]leucine) was administered to mice and they were dry-distilled, 14C-radioactivity was distributed into two fractions; residual solid and exhaust gas. In these cases, the recovery percentage of 14C in residual solid was not very high but increased as the treating temperature decreased. It reached about 40% of the administered 14C at 400 degrees C for 120 min. By the dry-distillation of animals, their weight was reduced to about 10% in every animal tested (mice, rats and rabbits). The volume was reduced to about 20% in cases of mice and rats, and about 30% in case of rabbits. It was concluded that the dry-distillation can be useful as a pre-treatment for disposal of animal wastes containing radioisotopes.     

Licensing in the italian regulatory system in the use of radioisotopes

The regulatory system in force in Italy concerning radioisotopes is based on two statutes dating back to 1962 and 1964; the latter is based on a 1962 Directive of European Community, of which Italy is a Member. European Directives of 1980, 1984, 1989, 1990 and 1992 will be enacted into Italian legislation by January 1^st, 1996. In the statutes in force the basic rules are established governing the holding and use of, trading in and disposal of radioactive material. These activities are subject to notification and licensing. Notification and licensing are based on two tiered system: a local, regional or provincial level and a national one, depending on the intersection of a number of parameters. The role of the governmental organs, state agencies such as ANPA (National Agency for Environmental Protection), local administrative bodies, their competence and their powers are discussed with regard to notification and licensing.     

DMSA and its complexes with radioisotopes: review

Meso-2,3-dimercaptosuccinic acid (DMSA) forms stable complexes with a remarkable wide range of metal ions. This relatively small molecule has attracted increasing attention in the field of radiopharmacy, treatment of heavy metal intoxications and nanoparticles preparation. In this review detailed summary of all physical, chemical and biological properties of DMSA and its complex compounds with ^99mTc, ^186/188Re, ¹⁶⁶Ho, ¹⁷⁷Lu and ⁹⁰Y is provided. The clinical utilisation of DMSA complexes in the nuclear medicine and its use for treatment of heavy metal intoxication is briefly summarised. The aspects of its application in the field of nanoparticles preparation is behind the scope of this review, therefore it is only shortly described.