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Title: A kinematically complete, interdisciplinary, and co-institutional measurement of the 19F(α,n) cross section for nuclear safeguards science

Abstract

Alpha particles emitted from the decay of uranium in a UF 6 matrix can interact with fluorine and generate neutrons via the 19F(α,n) 22Na reaction. These neutrons can be used to determine the uranium content in a UF 6 storage cylinder. The accuracy of this self-interrogating, non-destructive assay (NDA) technique is, however, limited by the uncertainty of the 19F(α,n) 22Na cross section. We have performed complementary measurements of the 19F(α,n) 22Na reaction with both 4He and 19F beams to improve the precision of the 19F(α,n) 22Na cross section over the alpha energy range that encompasses common actinide alpha decay needed for NDA studies. We have determined an absolute cross section for the 19F(α,n) 22Na reaction to an average precision of 7.6% over the alpha energy range of 3.9 – 6.7 MeV. We utilized this cross section in a simulation of a 100 g spherical UF 6 assembly and obtained a change in neutron emission rate values of approximately 10-12%, and a significant (factor of 3.6) decrease in the neutron emission rate uncertainty (from 50-51% to 13-14%), compared to simulations using the old cross section. Our new absolute cross section enables improved interpretations of NDAs of containers of arbitrary size andmore » configuration.« less

Authors:
 [1];  [2];  [2];  [3];  [3];  [4];  [2];  [5];  [2];  [4];  [4];  [4];  [6];  [6];  [6];  [6];  [6];  [6];  [6];  [6] more »;  [6];  [6];  [6];  [6];  [6];  [7]; ; ;  [7];  [6];  [6];  [6];  [8];  [9];  [3] « less
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Idaho National Lab. (INL), Idaho Falls, ID (United States)
  4. Rutgers Univ., New Brunswick, NJ (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Michigan, Ann Arbor, MI (United States)
  6. Univ. of Notre Dame, IN (United States)
  7. Univ. of Tennessee, Knoxville, TN (United States)
  8. Colorado School of Mines, Golden, CO (United States)
  9. Tennessee Technological Univ., Cookeville, TN (United States)
Publication Date:
Research Org.:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation (NA-20)
Contributing Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rutgers Univ., New Brunswick, NJ (United States); Univ. of Notre Dame, IN (United States); Univ. of Tennessee, Knoxville, TN (United States)
OSTI Identifier:
1263500
Report Number(s):
INL/EXT-16-38791
TRN: US1601611
DOE Contract Number:
AC07-05ID14517
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION; SODIUM 22; FLUORINE 19 TARGET; URANIUM HEXAFLUORIDE; ALPHA DECAY; MEV RANGE 01-10; NEUTRONS; NEUTRON EMISSION; SPHERES; EXCITATION FUNCTIONS; ACCURACY; URANIUM; ALPHA REACTIONS; SAFEGUARDS; COMPUTERIZED SIMULATION; GAS CYLINDERS; STORAGE; NUCLEAR REACTION ANALYSIS; COMPOUND-NUCLEUS REACTIONS; F(alpha,n)

Citation Formats

Peters, W. A., Smith, M. S., Pittman, S., Thompson, S. J., Clement, R. R. C., Cizewski, J. A., Pain, S. D., Febbraro, M., Chipps, K. A., Burcher, S., Manning, B., Reingold, C., Avetisyan, R., Battaglia, A., Chen, Y., Long, A., Lyons, S., Marley, S. T., Seymour, C., Siegl, K. T., Smith, M. K., Strauss, S., Talwar, R., Bardayan, D. W., Gyurjinyan, A., Smith, K., Thornsberry, C., Thompson, P., Madurga, M., Stech, E., Tan, W. P., Wiescher, M., Ilyushkin, S., Tully, Z., and Grinder, M. M. A kinematically complete, interdisciplinary, and co-institutional measurement of the 19F(α,n) cross section for nuclear safeguards science. United States: N. p., 2016. Web. doi:10.2172/1263500.
Peters, W. A., Smith, M. S., Pittman, S., Thompson, S. J., Clement, R. R. C., Cizewski, J. A., Pain, S. D., Febbraro, M., Chipps, K. A., Burcher, S., Manning, B., Reingold, C., Avetisyan, R., Battaglia, A., Chen, Y., Long, A., Lyons, S., Marley, S. T., Seymour, C., Siegl, K. T., Smith, M. K., Strauss, S., Talwar, R., Bardayan, D. W., Gyurjinyan, A., Smith, K., Thornsberry, C., Thompson, P., Madurga, M., Stech, E., Tan, W. P., Wiescher, M., Ilyushkin, S., Tully, Z., & Grinder, M. M. A kinematically complete, interdisciplinary, and co-institutional measurement of the 19F(α,n) cross section for nuclear safeguards science. United States. doi:10.2172/1263500.
Peters, W. A., Smith, M. S., Pittman, S., Thompson, S. J., Clement, R. R. C., Cizewski, J. A., Pain, S. D., Febbraro, M., Chipps, K. A., Burcher, S., Manning, B., Reingold, C., Avetisyan, R., Battaglia, A., Chen, Y., Long, A., Lyons, S., Marley, S. T., Seymour, C., Siegl, K. T., Smith, M. K., Strauss, S., Talwar, R., Bardayan, D. W., Gyurjinyan, A., Smith, K., Thornsberry, C., Thompson, P., Madurga, M., Stech, E., Tan, W. P., Wiescher, M., Ilyushkin, S., Tully, Z., and Grinder, M. M. Sun . "A kinematically complete, interdisciplinary, and co-institutional measurement of the 19F(α,n) cross section for nuclear safeguards science". United States. doi:10.2172/1263500. https://www.osti.gov/servlets/purl/1263500.
@article{osti_1263500,
title = {A kinematically complete, interdisciplinary, and co-institutional measurement of the 19F(α,n) cross section for nuclear safeguards science},
author = {Peters, W. A. and Smith, M. S. and Pittman, S. and Thompson, S. J. and Clement, R. R. C. and Cizewski, J. A. and Pain, S. D. and Febbraro, M. and Chipps, K. A. and Burcher, S. and Manning, B. and Reingold, C. and Avetisyan, R. and Battaglia, A. and Chen, Y. and Long, A. and Lyons, S. and Marley, S. T. and Seymour, C. and Siegl, K. T. and Smith, M. K. and Strauss, S. and Talwar, R. and Bardayan, D. W. and Gyurjinyan, A. and Smith, K. and Thornsberry, C. and Thompson, P. and Madurga, M. and Stech, E. and Tan, W. P. and Wiescher, M. and Ilyushkin, S. and Tully, Z. and Grinder, M. M.},
abstractNote = {Alpha particles emitted from the decay of uranium in a UF6 matrix can interact with fluorine and generate neutrons via the 19F(α,n)22Na reaction. These neutrons can be used to determine the uranium content in a UF6 storage cylinder. The accuracy of this self-interrogating, non-destructive assay (NDA) technique is, however, limited by the uncertainty of the 19F(α,n)22Na cross section. We have performed complementary measurements of the 19F(α,n)22Na reaction with both 4He and 19F beams to improve the precision of the 19F(α,n)22Na cross section over the alpha energy range that encompasses common actinide alpha decay needed for NDA studies. We have determined an absolute cross section for the 19F(α,n)22Na reaction to an average precision of 7.6% over the alpha energy range of 3.9 – 6.7 MeV. We utilized this cross section in a simulation of a 100 g spherical UF6 assembly and obtained a change in neutron emission rate values of approximately 10-12%, and a significant (factor of 3.6) decrease in the neutron emission rate uncertainty (from 50-51% to 13-14%), compared to simulations using the old cross section. Our new absolute cross section enables improved interpretations of NDAs of containers of arbitrary size and configuration.},
doi = {10.2172/1263500},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun May 01 00:00:00 EDT 2016},
month = {Sun May 01 00:00:00 EDT 2016}
}

Technical Report:

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  • The goal of this proposal is to enable neutron detection for precision Non-Destructive Assays (NDAs) of actinide-fluoride samples. Neutrons are continuously generated from a UFx matrix in a container or sample as a result of the interaction of alpha particles from uranium-decay α particles with fluorine nuclei in the matrix. Neutrons from 19F(α,n)22Na were once considered a poorly characterized background for assays of UFx samples via 238U spontaneous fission neutron detection [SMI2010B]. However, the yield of decay-α-driven neutrons is critical for 234,235U LEU and HEU assays, as it can used to determine both the total amount of uranium and themore » enrichment [BER2010]. This approach can be extremely valuable in a variety of safeguard applications, such as cylinder monitoring in underground uranium storage facilities, nuclear criticality safety studies, nuclear materials accounting, and other nonproliferation applications. The success of neutron-based assays critically depends on an accurate knowledge of the cross section of the (α,n) reaction that generates the neutrons. The 40% uncertainty in the 19F(α,n)22Na cross section currently limits the precision of such assays, and has been identified as a key factor in preventing accurate enrichment determinations [CRO2003]. The need for higher quality cross section data for (α,n) reactions has been a recurring conclusion in reviews of the nuclear data needs to support safeguards. The overarching goal of this project is to enable neutron detection to be used for precision Non- Destructive Assays (NDAs) of actinide-fluoride samples. This will significantly advance safeguards verification at existing declared facilities, nuclear materials accounting, process control, nuclear criticality safety monitoring, and a variety of other nonproliferation applications. To reach this goal, Idaho National Laboratory (INL), in partnership with Oak Ridge National Laboratory (ORNL), Rutgers University (RU), and the University of Notre Dame (UND), will focus on three specific items: (1) making a precision (better than 10 %) determination of the absolute cross section of the 19F(α,n)22Na reaction as a function of energy; (2) determining the spectrum of neutrons and γ-rays emitted from 19F(α,n)22Na over an energy range pertinent to NDA; and (3) performing simulations with this new cross section to extract the neutron yield (neutrons/gram/second) and resulting neutron- and gamma ray-spectra when α particles interact with fluorine nuclei in actinide samples, to aid in the design and reduce uncertainty of future NDA measurements and simulations.« less
  • the {sup 19}F(n,2n){sup 18}F cross section was measured at neutron energies of 18, 21, 23, and 27 MeV. Nearly monoenergetic neutrons bombarded teflon (CF{sub 2}), Zr, and Au samples. {sup 19}F(n,2n){sup 18}F cross section values were determined relative to {sup nat}Zr(n,xn){sup 89}Zr and {sup 197}Au(n,2n){sup 196}Au from measurements of the {sup 18}F, {sup 89}Zr, and {sup 196}Au activities. Our results are in agreement with previous measurements below 20 MeV and extend the usefulness of this reaction to 27 MeV. 22 refs., 1 fig., 2 tabs.
  • The breakup reaction {sup 4}He({ital {rvec d}},{ital p}{alpha}){ital n} at {ital E}{sub {ital d}}=7.0 MeV has been investigated in a kinematically complete experiment with vector and tensor polarized deuterons in a kinematical situation with zero relative energy of the two outgoing nucleons, a preferred situation to show effects from the singlet deuteron {ital d}{sup *} and therefore isospin breaking. A complete set of analyzing powers, {ital A}{sub {ital y}}, {ital A}{sub {ital y}{ital y}}, {ital A}{sub {ital x}{ital z}}, and {ital A}{sub {ital z}{ital z}} in addition to the differential breakup cross section, {ital d}{sup 3}{sigma}/{ital d}{Omega}{sub 3}{ital d}{Omega}{sub 4}{italmore » dS} has been measured. The data are compared to new Faddeev calculations including an approximate (cutoff) Coulomb potential allowing for the {ital d}{sup *} production and also {ital D}-wave {alpha}-{ital N} interactions. Good agreement is found for the polarization observables and the shape of the cross section which, however, disagrees in absolute magnitude. Both the inclusion of the {ital d}{sup *} and of {ital D} waves seem necessary for a good description of all data and for the interpretation of a small excursion in some observables in the {ital n}-{ital p} final-state interaction region as a manifestation of the isospin-forbidden {ital d}{sup *}.« less
  • Knowledge of the astrophysical {sup 18}F(p,{alpha}){sup 15}O rate is important for understanding gamma-ray emission from novae and heavy-element production in x-ray bursts. A state with E{sub x}{approx_equal}7.08 MeV in {sup 19}Ne provides an s-wave resonance and, depending on its properties, could dominate the {sup 18}F(p,{alpha}){sup 15}O rate. By measuring a kinematically complete {sup 1}H({sup 18}F,p){sup 18}F excitation function with a radioactive {sup 18}F beam at the ORNL Holifield Radioactive Ion Beam Facility, we find that the {sup 19}Ne state lies at a center-of-mass energy of 665.3{+-}1.7 keV (E{sub x}=7077{+-}2 keV), has a total width of 38.5{+-}3.4 keV, and a protonmore » partial-width of 15.8{+-}1.6 keV.« less