Izvestia Vysshikh Uchebnykh Zawedeniy. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Use of mathematical simulation to extend the scope of applicability for the procedure to measure the mass of 235u in solid radioactive waste

11/15/2018 2018 - #04 Modelling processes at nuclear facilities

Rykov N.S. Bezhunov G.M. Gorbachyov V.M.

DOI: https://doi.org/10.26583/npe.2018.4.09

UDC: 53.088.4:621.039.7

Determination of the mass (activity) of 235U in solid radioactive waste by gamma-spectroscopic method requires the use of the known dependence of absolute efficiency on energy and space for particular conditions of measurement. The In Situ Object Counting System (ISOCS) eliminates the need for laborious and time-consuming graduation measurements using reference standards to obtain the absolute efficiency curve since the so-called characterized detector is used which has a file with a set of efficiencies for different measurement geometries.

In many cases, a set of reference standards with parameters exceeding the range of the 235U mass measurement in the variation ranges of influencing factors, including density, nonuniformity, isotopic composition, geometry, etc., is highly expensive and, most often, impossible to create. Proceeding from this, a computational and experimental approach was adopted using the results obtained by Monte Carlo method based on the MCNP code with variation of the key influencing parameters within broad intervals.

Calculations were performed for detector-recorded spectra of gamma-quanta from a cask that contained waste differing in the density of the cask content (the density was calculated with regard for the uranium contained in waste) – in a range of 0.016 to 1 g/cm3, in the mass of uranium in the waste – in a range of 0.64 g to 2 kg, and in the matrix material (graphite, cellulose, quartz, cellulose with 20% of iron powder).

Boundaries have been defined for the applicability of the developed procedure to measure uranium-containing waste in terms of the material matrix (~ 2.2%) and its density (~ 10%), and the contribution of the uncertainty of the cask-contained uranium mass to the obtained result has been estimated (5% for dense matrices, 10% for porous matrices).

References

  1. In Situ Object Counting System. Available at: http://www.canberra.com/products/ insitu_systems/isocs.asp (accessed Jan 15, 2018).
  2. In Situ Object Counting System (ISOCS) as Applied to Scan Requirements in Support of Final Status Survey at HBPP. Available at: https://www.nrc.gov/docs/ML1313/ML13130A140.pdf (accessed Jan 15, 2018).
  3. Federal Law No. 102-FZ «About Ensuring Unity of Measurements» of 26.07.2008 (with changes of July 13, 2015). Available at: http://docs.cntd.ru/document/902107146 (accessed Jan 15, 2018).
  4. OST 95 10353-2007. Standard of Branch. Branch System of Ensuring Unity of Measurements. Algorithms of Assessment of Metrological Characteristics at Certification of Techniques of Performance of Measurements. Available at: http://www.metroatom.ru/download/metroatom/norm/metrology/ost_95_10353_2007.pdf (accessed Jan 15, 2018).
  5. OST 95 10289-2005. Standard of Branch. Branch System of Ensuring Unity of Measurements. Internal Quality Control of Measurements. Available at: http://www.metroatom.ru/download/metroatom/norm/metrology/OST_new_95%2010289.pdf (accessed Jan 15, 2018).
  6. OST 95 10571-2002. Standard of Branch. Account and Control of Nuclear Materials. Measuring System. Basic Provisions. Available at: http://docs.cntd.ru/document/1200035843 (accessed Jan 15, 2018).
  7. Ahnazarova S.L., Kafarov V.V. Methods of optimization of an experiment in chemical technology. Mosсow. Vysshaya shkola Publ., 1985, 327 p. (in Russian).
  8. Laborie J.-M., Le Petit G., Abt D., Girard M. Monte Carlo calculation of the efficiency response of a low-background well-type detector. Nuclear Instrument and Methods in physics research, 2002, v. 479, no. 2-3, pp. 618-630.
  9. Sima O. Applications of Monte Carlo calculations to gamma-spectrometric measurements of environmental samples. Applied Radiation and Isotope, 1996, v. 47, no. 9-10, pp. 919-923.
  10. General Monte Carlo N-Particle (MCNP) Transport Code. Available at: https:// laws.lanl.gov/vhosts/mcnp.lanl.gov/mcnp5.shtml (accessed Jan 15, 2018).
  11. Kolesov V.V. Use of the MCNP program for carrying out neutron and physical calculation of nuclear reactors. Obninsk. OGTUAE Publ., 2008, 44 p.
  12. Korobejnikov V.V. The Monte Carlo method in problems of physics of reactors and protection. Obninsk. IATE Publ., 1994, 84 p.
  13. MCNP HPGe detector benchmark with previously validated Cyltran model. Available at: https://www.researchgate.net/publication/24177539_MCNP_HPGe_detector_benchmark_with_previously_validated_Cyltran_model (accessed Jan 15, 2018).
  14. MCNP a general Monte Carlo N-particle transport code. Available at: https:// permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-13709-M (accessed Jan15, 2018).
  15. Genie 2000 Software family. Available at: http://www.canberra.com/products/radiochemistry_lab/genie-2000-software.asp (accessed Jan15, 2018).
  16. Table of Isotopes. Available at: https://application.wiley-vch.de/books/info/0-471-35633-6/toi99/toi.htm (accessed Jan 15, 2018).
  17. Doug Reilly, Nobert Ensslin, Hasting Smith Jr and Sarah Kreiner. Passive Nondestructive Assay of Nuclear Materials, Washington, U.S. Government Printing Office, 1996 , 700 p.
  18. XCOM: Photon cross-sections on a personal computer. Available at: https://nvlpubs.nist.gov/nistpubs/Legacy/IR/nbsir87-3597.pdf (accessed Jan15, 2018).
  19. Nuclide Navigator Version. Available at: https://www.ortec-online.com/products/application-software/nuclide-navigator (accessed Jan 15, 2018).

nondestructive analysis of nuclear materials solid radioactive waste uranium mass gamma-spectrometry ISOCS system absolute efficiency curve Monte Carlo method MCNP code measurement procedure measurement procedure range