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Alpha-Radiated Isotopes in Aqueous Media

#3829


Radiometer to Control Microconcentrations of Alpha-Emitting Isotopes in Aqueus Media

Tech Area / Field

  • INS-DET/Detection Devices/Instrumentation

Status
3 Approved without Funding

Registration date
10.10.2007

Leading Institute
VNIITF, Russia, Chelyabinsk reg., Snezhinsk

Supporting institutes

  • NPO Mayak, Russia, Chelyabinsk reg., Oziorsk

Collaborators

  • Pribori Oy, Finland, Turku\nCanberra Industries, USA, CT, Meriden

Project summary

Project goals: developing a radiometric device for real-time remote control over concentrations of uranium and plutonium isotopes, as well as other alpha-emitting isotopes in aqueous media.

Actuality of the Project proceeds from the need for the catch-all control over the content of radioactive substances in the environment, since their absolute amount in water, soil, air, foodstuffs is observed to increase due to wide application of radionuclides in power engineering, military and civilian industries, medicine and many other areas of production and economical activity of people. Monitoring over movement of alpha-active isotopes in small concentrations is critically important on the one hand and labor-intensive on the other hand as compared to the general monitoring over application and propagation of radioactive substances.

Detection of aqueous media contamination by alpha-active nuclides is an important constituent of radiation ecology because of great biological effect alpha-radiation exerts on living organisms. Internal irradiation of people through indigestion of radionuclides with water and foodstuffs causes greater probability of cancer and other serious diseases. Therefore, norms regulating content of alpha-active nuclides, i.e. plutonium and uranium, in the environment, drinking water included, are extremely strict. RF Sanitary regulations state the admissible content of the majority of alpha-active radionuclides to be 1-5 Bq/kg. Efficient control if these regulations are observed is a difficult technical task, especially when consideration is given to mall concentrations, i.e. at the level and below admissible concentrations, as well as when it is necessary to monitor technological processes or industrial discharges of wastewater.

Many existing methods used to control plutonium and uranium envisage sampling and further laboratory investigations of these samples, or direct detection of alpha-particles with the help of a detector placed into the target medium. These methods do not allow online measurements of small concentrations because of great errors and labor intensity. Very often, radionuclides adsorbed on the detector components are a determinative factor.

General practice shows that the number of radionuclides in industrial wastewater discharged from nuclear fuel cycle plants is limited. Moreover, admissible concentrations of many known alpha-emitters in water are very close to each other. So, sometimes monitoring of radionuclides available in these discharges can include only measurements of the total activity without activity from inpidual isotopes being distinguished.

This Project proposes the method for sorption concentrating of uranium and transuranium elements from water on a film carrier under certain conditions. The film with radionuclides adsorbed on its surface is dried and then exposed to the detector of the alpha-radiometer. The radiometer registers -radioactivity of the sample. Then these data are processed and accumulated in the database.

To implement this method technically, it is proposed to develop a device for remote registration of specific alpha-activity of a liquid medium. Measurements are taken automatically in the unmanned mode. It is to be noted that measurements are taken in the automatic unmanned mode. Both special electronic equipment and a reference calibration alpha-source will ensure high stability and accuracy of the instrument. The RF-controller used in the instrument will allow just conversion of pulses from the detection unit and data communication to a personnel computer. A specially developed software will allow (i) calculating the specific activity of monitored isotopes, (ii) continuous registration of data, (iii) comparing the concentration of monitored isotopes with the reference levels, and (iv) if this level is exceeded, communication of the warning signal to a monitoring organization via a computer network with the instrument integrated with the help of a PC. Access to instrument-measured information via a local network will allow twenty-four-hour, continuous, objective, and real-time monitoring of measured values. If necessary, the remote visual control over instrument operation, sampling and measurement procedures is exercised with the help of the Web-camera, which is to be installed in close vicinity to the instrument and integrated in the computer network.

This instrument will enable both the remote control over the content of alpha-emitting nuclides in the wastewater and online changes in the mode of any technological process. This device will find its application at nuclear energy enterprises, nuclear power plants, at nuclear fuel recycling facilities, as well as in environmental and sanitary services for radioecological survey of natural water basins and sources.

This device will facilitate survey of contaminated territories and drastically reduce the cost of this work. A very important advantage of this method is: it can serve the basis to automate the clean-up process for the wastewater discharged from radiochemical enterprises.

The participant institutions (i) have preliminary developments that are helpful for successful fulfillment of the Project, (ii) developed and tested the fabrication procedure for the tape adsorbent based on the polymer film, (iii) investigated and determined optimal parameters for the sorption concentrating of uranium and plutonium microconcentrations, (iv) created the model units and inpidual testing stands intended to study how parameters of the target medium effect the measurement process, and (v) identified designs of inpidual units of the device.

Basic tasks to be solved within the Project

  1. Development of the adsorbing tape fabrication technology; fabrication of the adsorbent synthesis facility.
  2. Optimization of technological parameters for concentrating the uranium and plutonium microconcentrations by a film adsorbent.
  3. Studying the boundary parameters of the method applicability and identification of technical solutions that ensure maximum sensitivity and speed of the device, as well as stability and reproducibility of measurement results.
  4. Developing the laboratory prototype of the alpha-radiometer in order to have optimal design, metrological, technical, and servicing characteristics so that this radiometer would be suitable for reliable fast radioecological monitoring of the aqueous medium being contaminated by alpha-active nuclides and having chemical admixtures.

Expected results.

The final result of the Project will be (i) the laboratory prototype of the device, which will be developed for automated remote monitoring of minor specific concentrations of alpha-active nuclides in the aqueous medium, and will be capable of reliable detection of alpha-emitting nuclides in the presence of accompanying chemical and mechanical admixtures; (ii) the technology developed to fabricate the adsorbing tape that is capable of ensuring uniform distribution of nuclides and their reliable fixation for further measurements.

The laboratory prototype of the device developed within the Project is intended to have the following technical and servicing characteristics:

  • Counting mode of alpha-particles registration,
  • High accuracy of measurements in conditions of changing chemical composition of the aqueous medium,
  • Real-time operation,
  • Absence of limitations because of the radiation background,
  • Time of one measurement - not more than 45 min,
  • Minimal registered concentration is 1-5 Bq/l,
  • Capability to accumulate and convert registered data into real physical values,
  • Communication of the data via the computer network,
  • Remote monitoring over the process of sampling preparation and measurement,
  • Capability of the device for unattended twenty-four-hour operation.

Based on the laboratory and shop tests, the laboratory prototype developed within the Project can be further improved in order to have the updated modification of the device having commercial potential.


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