LABORATORY FOR MASS SPECTROMETRIC ANALYSIS

The laboratory for mass spectrometric analysis was established in 1973. The main line of laboratory's activity represents realization of researches in substance isotopic composition changes after their irradiating in nuclear reactors, in accelerators of charged particles, or treatment in other high-energy processes. Great attention is paid at Laboratory to permanent development and modernization of the systems in mass-spectrometers available, destine for ion registration, to improvement of sample preparation and isotopic composition measuring methods, and also to introduction of up-to-date techniques assuring increase in sensitivity of mass-spectrometers. The Laboratory has participated on repeated occasions in international inter-calibration experiments, such as Pafex-1, Pafex-2, IDA-80, CPOK-2, etc. On evidence of these experiments the Laboratory is included since 1976 into IAEA National Analytical Laboratory Network and to this very day takes an active part in programs for uranium and plutonium detecting by IDMS method in spent nuclear fuel and in various inspection samples.

A spectrum of problems to be solved by the Laboratory itself, or in cooperation with other analytical laboratories of the Institute, is wide enough:

General investigation lines

• isotopic analysis of spent nuclear fuel (SNF) and radioactive substances (RS), including analysis of IAEA inspection samples and participation in international experiments aimed at improvement of the method of isotopic dilution at SNF examination;
• participation in domestic and international programs for creation of standard RS patterns, and their isotopic composition certification;
• express isotopic analysis of REE, TUE, and other components of SNF in high-level process solutions;
• analysis of radioactive environmental contaminations and improvement of methods to identify TUE in natural objects;
• investigation of isotopic distributions of products from fission reactions and nuclear fission under an effect of intermediate and high energy charged particles.

Isotopic analysis of spent nuclear fuel (SNF) and RS is realized with mass-spectrometer TH-5 (of "VARIAN" Company, Germany) according to technique certified by the State Scientific and Metrological Center in 2001 (Certificate N223-09-2001 ). With the purpose of device calibration and to take into account discriminating effects they use high-accuracy standard patterns: plutonium CRM-128 and uranium SAL-9907. Control of measurement quantity, regularly realized with the help of these patterns allows to high precision determination of SNF isotopic composition. Basic error of measurements reaches at that 0.005 %.

In the last few years there was implemented a work cycle for examination of uranium, plutonium, REE, and TPE in samples of SNF from RBMK, WWER-440, WWER-1000, and FN reactors.

At the Laboratory they carry out the works to create and fabricate standard plutonium dioxide patterns of various isotopic composition (together with Radium Institute's Laboratory for analytical radiochemistry and a number research institutes of the Branch). From time to time on demand of other laboratories of RI the Laboratory takes part in certification of various element isotopic composition.

Here they elaborated an express mass-spectrometric technique to measure TUE and REE content and isotopic composition in non-separated high-level mixtures of actinoids. This technique is destined to solve the problems associated with SNF management and TPE transmutation, and also to identify Np, Pu, and Am in environmental samples.

The Laboratory is succeeded in development and practical application of methods for ultra-small substance quantity analysis (threshold of sensitivity - from 10^-14 to 10^-16 g), destined to detect environmental objects contaminated with such dangerous radioactive man-caused nuclides as Pu, Np, Am, ¹²⁹I etc. Mass-spectrometric analysis of isotopic composition of these contaminations allows not only determination of their concentration, but ascertaining of their origin too.

There is developed technique for U and Pu assay in IAEA inspection samples. The Laboratory is included into IAEA network of laboratories participating in the Program for revision of unstated activities at nuclear facilities.

The Laboratory actively participated in the works to study isotopic effects in high-energy nuclear reactions and to determine in experiments isotopic distributions of heavy nuclei fission fragments and products of light and intermediate weight nuclei fission under an effect of protons at 70 - 100 MeV and 1 GeV energies.

The technique for measuring of isotopic distribution of nuclear reaction products by mass-spectrometer "in-line" with accelerators, which had been designed and fabricated in RI, was also developed at the Laboratory. With the help of this technique in a period from 1973 to 1993 there was carried out a series of works on RI's synchrotron and on PNPI's synchrocyclotron.

The Laboratory is also equipped with high-resolution (н/dн = 10⁵) low-background mass-spectrometer, which has allowed measuring of weights for several short-lived nuclei-productsoriginating under an effect of high-energy protons. At present this device is subjected to modernization with the purpose to be used for isotopic analysis of ultra-small quantities of actinides in a substance.

рХВМЙЛБГЙЙ

1. Andreev-Saveliev V.M., Belyaev B.N., Gromova E.A., et al. Application of Technique of Ion-exchange Pitch Individual Grains, when assaying Plutonium in SNF. // Radiochemistry. - 1989. - v. 31 - No 4 - p. 145-152.
2. Belyaev B.N., Domkin V.D., Makarova T.P., et al. Identification of Ultra-small Quantities of бm, уm, and REE in SNF by Isitopic Dilution Method. // Radiochemistry. - 1997. -.v. 39, No 1, p. 61.
3. Stepanov A.V., Makarova T.P., Domkin V.D., et al. Nuclide Composition of RBMK-1000 Spent Nuclear Fuel Samples. // Preprint AEI-6266/3, M., 2003.
4. Belyaev B.N., Gavrilov V.M., Domkin V.D., et al. Plutonium Isotopic Composition in Soils and Possibilities to Identify Contamination Sources. // Atomic Energy. - 1997 -- v. 83. - No 4. - p.298-304.
5. Domkin V.D., Stepanov A.V., Tsvetkov O.S., et al. Pu Isotopic Composition in Bottom Sediments of Norwegian and Greenland Seas.// Atomic Energy. - 1999. - v. 87, - No 4. - p. 286.
6. Belyaev B.N., Domkin V.D., Ivanova L.M., et al. Pu Isotopic Composition and Sedimentation Density in Soils of Saint-Petersburg Suburbs. // Radiochemistry. - 2001. v. 43. - No 2. - p. 184-187.
7. Andronenko L.N., Andronenko M.N., Domkin V.D. et al. Inverse Kinematics Experiments on Disintegrations of U-238 Induced by Protons in Combination with (2E,2V) Measurements. // Preprint PNPI-2534. - Gatchina. - 2003.
8. Andronenko L.N., Andronenko M.N., Domkin V.D. et all. Nuclear Fission Identification in Disintegrations of Heavy and Medium-heavy Nuclei. // Preprint PNPI-2538. - Gatchina. - 2003.