Spectrometry and Radiochemistry
The Laboratory of Spectrometry and Radiochemistry of Polesye State Radiation-Ecological Reserve received its first accreditation certificate (reg.no.BY/112 02.2.0.2203) in 2002. In January 2016 the accreditation status meeting the ÑÒÁ ÈÑÎ/ÌÝÊ 17025:2007 requirements was extended until January 28, 2021. The laboratory accreditation scope includes sampling, determination of surface beta contamination, gamma rays dose rate, and also determination of 137Cs, 90Sr, 241Am, 238Pu, 239Pu,240Pu specific activity in environmental objects: soil, water, sediments, agriculture and forestry non-alimentary products, agricultural stock and forage, alimentary products. The laboratory is equipped with alpha/beta low-background unit with gas proportional counter, allowing to determine alpha-and-beta-emitting nuclides in 8 samples simultaneously. Two gamma spectrometers with high-purity germanium detectors with beryllium and carbon-filled plastic windows (Canberra) applied for 241Am uptake determination in environmental samples without prior sample preparation. For the purpose of radiochemical analyses conduct the system of microwave preparation Ethos, alpha spectrometer “Alpha Analyst” (Canberra), atomic-absorption spectrometer Solaar S2, and liquid-scintillation analyzer TRI CARB 2910 TR.
THE LABORATORY OF SPECTROMETRY AND RADIOCHEMISTRY
The accreditation scope of the laboratory of spectrometry and radiochemistry of Polesye State Radiation-Ecological Reserve:
- sampling of soil and non-alimentary products of agriculture and forestry;
- dose rate measuring;
- surface β-contamination measuring;
- determination of:
- 137Cs specific (volumetric) activity in environmental objects, agricultural stock, forage, water, alimentary products, non-alimentary products of agriculture and forestry;
- 90Sr uptake in alimentary products, agricultural stock, forage, soil, sediments, surface waters, flora and fauna specimens of Polesye State Radiation-Ecological Reserve;
- 241Am uptake in soil and sediments;
- uptake of 238Pu, 239Pu, 240Pu in soil, sediments, surface waters, flora and fauna specimens of Polesye State Radiation-Ecological Reserve.
One of the key tasks of the laboratory of spectrometry and radiochemistry is support of the reserve scientific departments with the results of radionuclide uptake analysis in provided environmental objects samples. In 2015 the laboratory employees carried out 3228 sample analyses on 137Cs, 90Sr and 241Am uptake applying the instrumental method and conducted radiochemical studies of 90Sr, 239+240Pu uptake in 157 samples.
The laboratory counts 11 employess who received special training at leading research-and-development centers of Slovenia, Austria and the Ukraine. The employees improve their professional skills on a regular basis by participating in advanced trainings held by native institutes. Objectivity of the analytical data is supported by the results of interlaboratory collative tests.
Objectivity of the laboratory deliverables are confirmed by the results of interlaboratory collative tests, annually held by accreditation authorities. In 2015 the laboratory took part in the following interlaboratory collative tests.
1. ÏÏÊ. ÃÌ-01-2015 tour ¹ 1 “Estimation of 137Cs radionuclides uptake in alimentary products, agricultural stock and forage, forestry products”. Provider – State enterprise “Gomel CSMC”.
2. Professional testing IAEA TEL 2015-3 PT “Estimation of anthropogenic and natural radionuclides in water, biota and soil”.
The results of sample analysis provided for interlaboratory collative tests ÏÏÊ. ÃÌ-01-2015 tour ¹ 1 were considered satisfactory. The results of IAEA professional testing were not quite reliable. The results on the majority gamma-emitting radionuclides (Cs-134, Cs-137, Na-22, Zn-65, Ac-228, Bi-214, Pb-210, Pb-212, Pb-214, Tl-208), as well as Pu-239, 240, were accepted; but the given Am-241 data proved understated (0.73 instead of 1.2 Bq/kg), and in case of Sr-90, the deviation proved even more significant. In compliance with the test results, it was decided to execute the following corrective measures: perform recalibration of gas stream counter, used at terminal definition stage of Sr-90, and also to retest the soil sample of IAEA professional testing.
The laboratory equipment is presented at the pictures below:
Economic activity of the laboratory:
- control of 137Cs uptake in carving wood, produced at the sawmills of Polesye State Radiation-Ecological Reserve in the settlements of Khoiniki, Narovlya, and Komaryn.
- adjustment of the map of radioactive contamination of Polesye State Radiation-Ecological Reserve territory with 137Cs, 90Sr, 241Am, 238Pu, 239+240Pu.
- examination of forest ranges in order to determine the wood usability for national economy. During the period from 2003 to 2015, 1560 sites with a total area of over 8100 ha had been examined.
The following pictures show some stages of radiation examination at falling sites.
It is established by the laboratory employees that 90Sr uptake in fuel wood in some areas of the reserve can exceed 2000Bq/kg, besides 137Cs uptake in the same fuel wood samples is not exceeding the allowed value (740Bq/kg). At present, in Belarus there’s no control of 90Sr uptake in fuel wood, unlike in the Ukraine and the Russian Federation. The laboratory employees assume that such control could prevent:
1. distribution of 90Sr from the contaminated territories into adjacent areas;
2. uncontrolled internal exposure of the population, who traditionally use ash as a fertilizer on their farmlands.
While determining the acceptable uptake of 90Sr in fuel wood it is important to base on the specifics of radioactive contamination of the territory of Belarus. Currently the laboratory stuff continues their works in this direction in compliance with the Program of joint cooperation in overcoming the consequences of the Chernobyl accident in terms of the Union State. In 2015 they are to work out the computation algorithm for allowable levels of 90Sr uptake in merchantable and fuel wood, produced in Polesye State Radiation-Ecological Reserve.
[V.N. Zabrodskiy. The uptake of 90Sr in fuel wood produced on the Belorussian territory of the Chernobyl NPP exclusion zone.//Natural resources, 2013, ¹2. P. 100-105.(Rus)]
Apart from support of other scientific departments of the reserve with results of their samples tests in radionuclides uptake, the laboratory conducts own research.
It is well known that radioactive contamination of the Chernobyl NPP exclusion zone is in the first place determined by presence of fuel particles formed with the explosion of the 4-th power unit reactor of the plant. The work objective is identification of fuel particles fallout on the territory of Polesye State Radiation-Ecological Reserve.
In order to have the task accomplished it is provisioned to apply a number of diverse physicochemical methods:
- soil sample handling with different solvents, in particular carbonate containing liquid, dissolving decayed fuel particles, but not influencing the initial nuclear fuel matrix of the 4-th power unit reactor of the Chernobyl NPP (UO2);
- soil sample fragmentation into small aliquots followed by their analyses applying the gamma-spectrometry method;
- repeated multiple soil samples mixing followed by gamma-spectrometry;
- analysis of the correlation between the radionuclides constituents of a fuel component of the Chernobyl fallout.
[V. N. Zabrodskiy, Yu.I. Bondar, V.N. Kalinin, V.I. Sadchikov. Evaluation of nuclear fuel particles decay rate. // Ecosystems and radiation: aspects of existence and development. Coll.scient.art., dedicated to the 25th anniversary of Polesye State Radiation-Ecological Reserve. / Under the general editorship of Yu.I. Bondar. Minsk: BORBITZ RRUE “Institute of Radiology”. 2013. C. 113-121.(Rus)]
Experimental data evaluating radionuclides content in soil and sediment samples collected on the territory of the reserve in 2008-2014 shows that peak quotient of 241Am/154Eu lies within 5.5. Theoretical estimation of this quotient for 2008 equaled 3.3.The laboratory came out with a suggestion that the cause for such discrepancy is disregard, in the process of theoretical calculation of 241Am/154Eu, of a sharp radioactivity increase in the active zone of the Chernobyl NPP 4th unit reactor at the time of the emergency, and consequently, an almost instantaneous increase in neutron flux density, which lead to the accident. The increase in neutron flux density in its turn lead to additional 241Pu recovery (parent element 241Am) and resulted in redistribution of other radionuclides in the Chernobyl fallout.
[V.I. Sadchikov, Yu.I. Bondar, V.N. Kalinin. Calculation of transuranium elements in the fuel of the Chernobyl NPP 4th unit reactor active zone based on the experimental values of their specific activity in the soils of southern Belarus exclusion zone sector. // Nuclear and radiation physics: mat. of the 9th intern. conf. (Sept. 24-27, 2013) – Almaty: RSE INP, 2013. P. 228-229(Rus)].
[V.I. Sadchikov, V.N. Zabrodskiy, Yu.I. Bondar, V.N. Kalinin. Estimation of 241Pu specific activity in the fuel of the Chernobyl NPP 4th unit reactor at the moment of the accident based on the experimental values of 241Am and 154Eu specific activity. Theses doc. / 5th International conference “Semipalatinsk proof ground”. Radiation population and prospects of development. September 12-14, 2012 Kurchatov, ÂÊÎ, the Republic of Kazakhstan(Rus)]
The laboratory conducts tests on transuranim elements (241Am, 238Pu, 239+240Pu) uptake in sample internals (muscular and bone tissues, liver, lungs) and gastric contents of wild animals, extracted on the territory of Polesye State Radiation-Ecological Reserve. It is established that with wild boars the liver is the most contaminated, and its 239+240Pu uptake can reach 1.5 Bq/kg. Contamination of organs and tissues drops in the following sequence: liver > bone tissue > lungs ≥ muscle tissue.
[Yu.I. Bondar, V.N. Zabrodskiy, V.I. Sadchikov, V.N. Kalinin. The uptake of plutonium isotopes in organs and tissues of the wild boar (Sus scrofa) on the territory of Polesye State-Radiation Ecological Reserve. // Izvestiya NAS of Belarus. Biological sciences series. 2014, ¹3. P. 94-100.(Rus)]
Participation in international projects
The “MOBELRAD” Project
The Fukushima accident proved significance of mobile systems in radioactive contamination control of the territory. The necessity in personnel training and testing of such equipment requires special conditions and special routes. From this point of view, the territory of the Belorussian sector of Chernobyl NPP exclusion zone makes an appropriate trial grounds. In September 2014 there were mobile trainings carried out on the territory of the reserve with participation of the laboratory stuff. Their goal was to determine the rate of the territory radioactive contamination with 137Cs, and estimate the equivalent dose rate of gamma-rays from automobile en route, equipped with dosimetric and spectrometric appliances. The trials were held with participation of teams from Denmark, Iceland, Norway, and Sweden, armed with different kinds of equipment – from small size appliances with detectors based on LaBr to large-size crystals NaI. The training defined usage possibilities for radiation measuring equipment in case of radiation accident in third countries. The report is available at: http://www.nks.org/en/nks_reports/view_document.htm?id=111010212617378
The project: “Ecological risk analysis in the exclusion zone at Belarus-Ukraine border” (in compliance with the international initiative “Environment and Security” (ENVSEC)).
Within the project the laboratory personnel, as well as employees from other reserve departments, are to perform the following activities at Belarus-Ukraine state border of 155km., passing through the Chernobyl NPP exclusion zone:
- gamma rays dose rating along the investigated area (880 measurements);
- soil sampling (160 samples) and estimation of 137Ñs and 241Am contamination density at the investigated area.
The analogous work is fulfilled by the Ukrainian side.
Head of the Laboratory of Spectrometry and Radiochemistry
Candidate Of Chemical Sciences