This title appears in the Scientific Report :
2016
Please use the identifier:
http://hdl.handle.net/2128/10254 in citations.
Cyclic neutron activation analysis of large samples with a pulsed 14 MeV neutron source
Cyclic neutron activation analysis of large samples with a pulsed 14 MeV neutron source
CYCLIC NEUTRON ACTIVATION ANALYSIS OF LARGE SAMPLES WITH A PULSED 14 MEV NEUTRON SOURCEFrank Mildenberger 1 – Eric Mauerhofer 11 Institute of Energy and Climate Research – Nuclear Waste Management and Reactor Safety, Forschungszentrum Juelich GmbH; 52425 Juelich, GermanyKeywords: large samples, 14 M...
Saved in:
Personal Name(s): | Mildenberger, Frank (Corresponding author) |
---|---|
Mauerhofer, Eric | |
Contributing Institute: |
Nukleare Entsorgung; IEK-6 |
Imprint: |
2016
|
Conference: | 1st International Conference on Radioanalytical and Nuclear Chemistry, Budapest (Hungary), 2016-04-10 - 2016-04-15 |
Document Type: |
Conference Presentation |
Research Program: |
Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) Nuclear Waste Management |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
CYCLIC NEUTRON ACTIVATION ANALYSIS OF LARGE SAMPLES WITH A PULSED 14 MEV NEUTRON SOURCEFrank Mildenberger 1 – Eric Mauerhofer 11 Institute of Energy and Climate Research – Nuclear Waste Management and Reactor Safety, Forschungszentrum Juelich GmbH; 52425 Juelich, GermanyKeywords: large samples, 14 MeV neutron sources, cyclic neutron activation, prompt and delayed gamma-rays Prompt gamma neutron activation analysis using a 14 MeV neutron generator is a promising analytical technique to determine nonradioactive elements in 200 L radioactive waste drums [1,2]. However further information on the elemental composition of the waste may be obtained measuring the delayed gamma rays of short-lived radionuclides (e.g. 16N, 24mNa, 27Mg, 28Al, 52V and 207mPb) induced by fast and thermal neutron reactions. In a previous study dealing with the die-away time of thermal neutrons in various large samples [3] we showed that a waiting of about 12 ms after the end of the neutron pulses is required to measure delayed gamma rays without appreciable interferences of prompt gamma rays.Cyclic neutron activation i.e. the subsequent measurement of prompt and delayed gamma rays between fast neutron pulses is applied for the analysis of the 200 L drum filled with concrete and a large lead sample. The neutron generator was operated in pulse mode at a neutron emission of about 8·107 n·s-1. The length of the neutron pulses was set to 2 ms and the repetition time to 40 ms. Using two multi channel analyzers the prompt gamma-rays were measured directly after the neutron pulses for 20 ms and the delayed gamma-rays for 20 ms after a waiting time of 18 ms from the end of the neutron pulses. Prompt and delay gamma-ray spectra were recorded for total counting time of 3600 s. In this work the methodology to determine the elemental composition of concrete is presented. It includes the evaluation of the fast and thermal neutron flux using the steel drum as monitor as well as correction factors based on thermal neutron die-away times for quantification through the prompt gamma rays measured in a decaying thermal neutron flux. The results are compared with those obtained by setting irradiation and counting conditions preferably for the measurement of thermal neutron capture gamma rays [2]. Finally characterization of a large lead sample using thermal neutron capture gamma rays and delayed gamma rays of the short-lived isotope 207mPb (T½ = 805 ms) induced by (n,2n)-reaction with fast neutrons is described.References[1] E. Mauerhofer, A. Havenith, The MEDINA facility for the assay of the chemotoxic inventory of radioactive waste packages, J. Radioanal. Nucl. Chem. (2014) 302:483-488[2] E. Mauerhofer, A. Haventih, J. Kettler, PGNAA of a 200 L steel drum filled with concrete, International Conference on Modern Trends in Activation Analysis MTAA-14, Delft University of Technology, Delft, The Netherlands, August 23-28, 2015.[3] F. Mildenberger, E. Mauerhofer (2015) Thermal neutron die-away times in large samples irradiated with a pulsed 14 MeV neutron source. J Radioanal. Nucl. Chem. DOI 10.1007/s10967-015-4178-2 |