Izvestiya vuzov. Yadernaya Energetika

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

On the Concept of Delayed Neutron Multiplication Factor

12/14/2022 2022 - #04 Personnel training

Yuferov A.G.

DOI: https://doi.org/10.26583/npe.2022.4.12

UDC: 621.039.514.4:621.039.515:621.039.516:378

The article considers methodological issues related to the conceptual and terminological apparatus of the dynamics of nuclear reactors. Based on an elementary analysis of the standard nuclear reactor dynamics equations, it is shown that the delayed neutron multiplication factor (DNMF) in the form of kdn = βkef, the product of the «effective delayed neutron fraction» by the population multiplication factor, has no physical meaning. This incorrectness is due to the fact that the parameter β does not express the actual fraction of delayed neutrons (DNs) in the population. It follows directly from the transfer equations that, in transient regimes, the rate of generation of DNs and, consequently, their fraction in the population are variable values. The concept of ‘multiplication factor’ as the ratio of the rates of generation and loss of particles is not applicable to DNs, since the transport equations do not describe the processes of their absorption and leakage. For this reason, the author proposes a number of meaningful and terminological clarifications of the concepts under consideration. Possible definitions of the parameters kef, kmn, kzn in conjunction with other parameters of the NR dynamics are considered. Alternative possibilities for reflecting the contribution of DNs to the dynamics of the total neutron population are presented. The options for determining the multiplication factor are compared based on the description of the NR dynamics in terms of generations and the balance of process rates. The non-identity of the multiplication factors appearing in the generation model and in the rate model is shown.

References

  1. Krupennikov V.P. Operational Issues of Physics of VVER0440 Reactors. Moscow. Energoatomizdat Publ., 1986, 80 p. (in Russian).
  2. Marguet S. The Physics of Nuclear Reactors. Springer Publ., 2017, 1462 p.
  3. Belozerov V.I., Zhuk M.M., Kuzina Yu.A., Ternov M.Yu. Physics and Operational Modes of the VVER01000 Reactor. Moscow. MEPhI Publ., 2014, 288 p. (in Russian).
  4. Popov A.K. Fundamentals of Nuclear Reactor Control. Moscow. MGU Publ., 2012, 208 p. (in Russian).
  5. Sarkisov A. A., Puchkov V. N. Neutron0Physical Processes in Fast Reactors with Heavy Liquid0Metal Heat Carriers. Moscow. Nauka Publ., 2011, 168 p. (in Russian).
  6. Vladimirov V.I. Physics of Nuclear Reactors: Practical Tasks for their Operation. Moscow. LIBROCOM Publ., 2009, 480 p. (in Russian).
  7. Yurkevich G.P. Power Reactor Control Systems. Moscow. ELEKS-KM Publ., 2001, 344 p. (in Russian).
  8. Sarkisov A.A., Puchkov V.N. Physics of Transients in Nuclear Reactors. Moscow. Energoatomizdat Publ., 1983, 264 p. (in Russian).
  9. Yemelyanov I.Ya., Efanov A.I., Konstantinov L.V. Scientific and Technical Fundamentals of Nuclear Reactor Control. Moscow. Energoizdat Publ., 1981, 360 p. (in Russian).
  10. Soodak Н., Campbell E.С. Elementary Pile Theory. Uspekhi Fizicheskikh Nauk. 1950, v. 42, pp. 93-156; DOI: https://doi.org/10.3367/UFNr.0042.195009g.0093 (in Russian).
  11. The IAEA Safety Glossary. IAEA, 2007, 295 p. (in Russian).
  12. NP-063-05. Rules of Nuclear Safety for Nuclear Fuel Cycle Facilities. Moscow. Rostechnadzor Publ., 2005, 21 p. (in Russian).
  13. McLaughlin T.P., Monahan S.P., Pruvost N.L., Frolov V.V., Ryazanov B.G., Sviridov V.I. A Review of Criticality Accidents. Los Alamos National Laboratory, LA-13638. 2000, 158 p.
  14. Glossary of Atomic Terms. Obninsk. FEI Publ. 1991, 72 p. (in Russian).
  15. Kolesov V.F. The Origins of Inaccuracies in Reactivity Determined by the Inverse Solution of Kinetic Equations. VANT. Ser. Fizika Yadernykh Reactorov. 2013, iss. 3, pp. 30-45 (in Russian).
  16. Yuferov A.G. About the Сoncept of Prompt Criticality. Izvestiya vuzov. Yadernaya Energetika. 2021, no. 4, pp. 135-145; DOI: https://doi.org/10.26583/npe.2021.4.12 (in Russian).
  17. Yuferov A.G. On the Concept of Effective Delayed Neutron Fraction. Izvestiya vuzov. Yadernaya Energetika. 2022, no. 2, pp. 174-182; DOI: https://doi.org/10.26583/npe.2022.2.16 (in Russian).
  18. Kuzmin A.M. Fundamentals of Criticality Theory, Calculation Methods and Reactor Reactivity Perturbation. Moscow. MEPhI Publ., 2008. 156 p. (in Russian).
  19. Seleznev E.F. Kinetics of Fast Neutron Reactors. Moscow. Nauka Publ., 2013, 239 p. (in Russian).
  20. Bell D., Glesson S. Theory of Nuclear Reactors. Moscow. Atomizdat Publ., 1974. 489 p. (in Russian).
  21. Reactor Criticality and Conditions for its Implementation. Available at: portal.tpu.ru (accessed Jul. 23, 2022) (in Russian).
  22. Physics and Kinetics of TRIGA Reactors. Available at: https://ansn.iaea.org/Common/documents/Training/ TRIGA Reactors (Safety and Technology)/pdf/chapter2.pdf (accessed Jul. 23, 2022) (in Russian).

nuclear reactor dynamics delayed neutron multiplication factor

Link for citing the article: Yuferov A.G. On the Concept of Delayed Neutron Multiplication Factor. Izvestiya vuzov. Yadernaya Energetika. 2022, no. 4, pp. 134-146; DOI: https://doi.org/10.26583/npe.2022.4.12 (in Russian).

Open PDF file