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Title: Annual Report FY2013-- A Kinematically Complete, Interdisciplinary, and Co-Institutional Measurement of the 19F(α,n) Cross-section for Nuclear Safeguards Science

Technical Report ·
DOI:https://doi.org/10.2172/1154645· OSTI ID:1154645
 [1];  [1];  [2];  [3];  [3];  [4];  [5];  [1]
  1. ORNL
  2. INL
  3. University of Notre Dame
  4. Rutgers University
  5. University of Michigan
+ Show Author Affiliations

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 the 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.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
Contributing Organization:
University of Michigan; Rutgers University; University of Notre Dame
DOE Contract Number:
DE-AC05-00OR22725
OSTI ID:
1154645
Report Number(s):
ORNL/TM-2013/484; R&D Project: NN2001000
Country of Publication:
United States
Language:
English

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