Conceptual design of neutron measurement system for input accountancy in pyroprocessing

  • Lee, Chaehun (Korea Atomic Energy Research Institute) ;
  • Seo, Hee (Chonbuk National University) ;
  • Menlove, Spencer H. (Safeguards Technical Solutions) ;
  • Menlove, Howard O. (Los Alamos National Laboratory)
  • Received : 2018.11.14
  • Accepted : 2019.11.05
  • Published : 2020.05.25


One of the possible options for spent-fuel management in Korea is pyroprocessing, which is a process for electrochemical recycling of spent nuclear fuel. Nuclear material accountancy is considered to be a safeguards measure of fundamental importance, for the purposes of which, the amount of nuclear material in the input and output materials should be measured as accurately as possible by means of chemical analysis and/or non-destructive assay. In the present study, a neutron measurement system based on the fast-neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) techniques was designed for nuclear material accountancy of a spent-fuel assembly (i.e., the input accountancy of a pyroprocessing facility). Various parameters including inter-detector distance, source-to-detector distance, neutron-reflector material, the structure of a cadmium sleeve around the close detectors, and an air cavity in the moderator were investigated by MCNP6 Monte Carlo simulations in order to maximize its performance. Then, the detector responses with the optimized geometry were estimated for the fresh-fuel assemblies with different 235U enrichments and a spent-fuel assembly. It was found that the measurement technique investigated here has the potential to measure changes in neutron multiplication and, in turn, amount of fissile material.


  1. Nuclear Safety and Security Commission, Nuclear safety information center.
  2. H. Lee, G.I. Park, J.W. Lee, et al., Current status of pyroprocessing development at KAERI, Sci. Technol. Nucl. Install. 2013 (2013) 343492.
  3. J.P. Ackerman, Chemical basis for pyrochemical reprocessing of nuclear fuel, I&EC Res. 30 (1991) 141-145.
  4. J.J. Laidler, J.E. Battles, W.E. Miller, J.P. Ackerman, E.L. Carls, Development of pyroprocessing technology, Prog. Nucl. Energy 31 (1997) 131-140.
  5. S.X. Li, S.D. Herrmann, K.M. Goff, M.F. Simpson, R.W. Benedict, Actinide recovery experiments with bench-scale liquid cadmium cathode in real fission product-laden molten salt, Nucl. Technol. 165 (2009) 190-199.
  6. M.F. Simpson, Developments of Spent Nuclear Fuel Pyroprocessing Technology at Idaho National Laboratory, Idaho Natl. Lab., 2012, pp. 1-21. INL/EXT-12-25124.
  7. International Atomic Energy Agency, The Structure and Content of Agreements between the Agency and States Required in Connection with the Treaty on the Non-proliferation of Nuclear Weapons, INFCIRC/153, 1972 (Corrected).
  8. P.C. Durst, I. Therios, R. Bean, A. Dougan, B.D. Boyer, R. Wallace, M. Ehinger, D. Kovacic, L. Tolk, Advanced Safeguards Approaches for New Reprocessing Facilities, Pacific Northwest Natl. Lab., 2007. PNNL-16674.
  9. H. Seo, B.H. Won, S.K. Ahn, S.K. Lee, S.H. Park, G.I. Park, S.H. Menlove, Optimization of hybrid-type instrumentation for Pu accountancy of U/TRU ingot in pyroprocessing, Appl. Radiat. Isot. 108 (2016) 16-23.
  10. H. Seo, S.K. Lee, S.J. An, S.H. Park, J.H. Ku, H.O. Menlove, C.D. Rael, A.M. LaFleur, M.C. Browne, Development of prototype induced-fission-based Pu accountancy instrument for safeguards applications, Appl. Radiat. Isot. 115 (2016) 67-73.
  11. H.O. Menlove, S.H. Menlove, C.D. Rael, The development of a new, neutron, time correlated, interrogation method for measurement of 235U content in LWR fuel assemblies, Nucl. Instrum. Methods 701 (2013) 72-79.
  12. J.S. Beaumont, T.H. Lee, M. Mayorov, C. Tintori, F. Rogo, B. Angelucci, M. Corbo, A fast-neutron coincidence collar using liquid scintillators for fresh fuel verification, J. Radioanal. Nucl. Chem. 314 (2017) 803-812.
  13. H.O. Menlove, A. Belian, W. Geist, C. Rael, A new method to measure the U- 235 content in fresh LWR fuel assemblies via fast-neutron passive selfinterrogation, Nucl. Instrum. Methods 877 (2018) 238-245.
  14. S.J. Tobin, H.O. Menlove, M.T. Swinhoe, M.A. Schear, Next Generation Safeguards Initiative research to determine the Pu mass in spent fuel assemblies: purpose, approach, constraints, implementation, and calibration, Nucl. Instrum. Methods 652 (2011) 73-75.
  15. J. Eigenbrodt, Spent fuel measurements: passive neutron albedo reactivity (PNAR) and photon signatures, Ph.D. Dissertation, in: Nuclear Engineering, Texas A&M University, College Station, TX, 2016.
  16. D. Henzlova, H.O. Menlove, C.D. Rael, H.R. Trellue, S.J. Tobin, S.H. Park, J.M. Oh, S.K. Lee, S.K. Ahn, I.C. Kwon, H.D. Kim, Californium interrogation prompt neutron (CIPN) instrument for non-destructive assay of spent nuclear fuelddesign concept and experimental demonstration, Nucl. Instrum. Methods 806 (2016) 43-54.
  17. A.M. Lafleur, W.S. Charlton, H.O. Menlove, M.T. Swinhoe, A.R. Lebrun, Development of self-interrogation neutron resonance Densitometry to improve detection of possible diversions for PWR spent fuel assemblies, Nucl. Technol. 181 (2013) 354-370.
  18. A.C. Kaplan, V. Henzl, H.O. Menlove, M.T. Swinhoe, A.P. Belian, M. Flaska, S.A. Pozzi, Determination of spent nuclear fuel assembly multiplication with the differential die-away self-interrogation instrument, Nucl. Instrum. Methods 757 (2014) 20-27.
  19. T. Martinik, V. Henzl, S. Grape, P. Jansson, M.T. Swinhoe, A.V. Goodsell, S.T. Tobin, Design of a prototype differential die-away instrument proposed for Swedish spent nuclear fuel characterization, Nucl. Instrum. Methods 821 (2016) 55-65.
  20. S.T. Tobin, P. Jansson, Nondestructive Assay Options for Spent Fuel Encapsulation, Swedish Nuclear Fuel and Waste Management Co., 2013. TR-13-30.
  21. D.B. Pelowitz (Ed.), MCNP6 User's Manual Version 1.0, Los Alamos Natl. Lab., 2013. LA-CP-13-00634.
  22. A.M. LaFleur, S.K. Ahn, H.O. Menlove, M.C. Browne, H.D. Kim, Characterization and performance evaluation of a new passive neutron albedo reactivity counter for safeguards measurements, Radiat. Meas. 61 (2014) 83-93.
  23. Victrex plc.
  24. I.C. Gauld, S.M. Bowman, J.E. Horwedel, ORIGEN-ARP: Automatic Rapid Processing for Spent Fuel Depletion, Decay, and Source Term Analysis, Oak Ridge Natl. Lab., 2014. ORNL/NUREG/CSD-2/V1/R7.H.