1. Development of Active Neutron Non-Destructive Assay (NDA) Techniques
– An Overview of Collaboration Projects of the JAEA, EC-JRC, and Kyoto University –
1) M. Koizumi, Y. Toh, A. Ohzu, H. Tsuchiya, K. Furutaka, M. Maeda, F. Kitatani, M. Kureta, D.C. Rodriguez,
F. Rossi, M. Seya, J. Takamine, T. Takahashi, H. Tomikawa, M. Hori
2) P. Schillebeeckx, K. Abbas, B. Pedersen, T. Bogucarska, J.-M. Crochemore
3) J. Hori
1) Japan Atomic Energy Agency (JAEA)
2) Joint Research Centre
3) Institute for Integrated Radiation and Nuclear Science, Kyoto University
ID: xxx
ABSTRACT
OUTCOME
We are developing four active neutron nondestructive assay (NDA) techniques, which would be potentially useful for quantification of nuclear materials (NM) in a high-level radioactive sample.
The techniques will be complementary used for sample analysis
The first stage of this project, which is basic technological developments using low-level radioactive samples, has finished. Technological developments aiming at high-level radioactive NM sample measurement is in progress.
DDA: The developed DDA system is potentially useful for quantification of 239Pu mass ( mg) in a small volume sample (vial bottle (f26×40 mm)).
PGA: The developed PGA system can be detect the existence of elements of N, As, P, Cl, and S from neutron induced gamma-ray signals.
NRTA: According to a simulation study, areal densities of 238U and 239,240,242Pu can be deduced form a transmission spectrum measured by using a DT neutron source (pulse width of 10 µs).
DGA: Delayed gamma-ray spectra measured with an instrument (PUNITA) of EC-JRC Ispra indicate applicability of a DDA techniques to analyze relative concentration of fissile nuclides.
The four techniques can be applied for complementary analysis of a NM sample; Table 2 shows examples. PGA would be useful to diagnose matrix material of a sample, such as neutron poisons that should be accounted in the other measurement.
BACKGROUND
NDA methods are an efficient and quick way to quantify NMs. However, commonly used passive NDA techniques are not applicable to measure a high-level radioactive NM sample.
Active neutron NDA techniques, which utilize neutron to induce nuclear reactions to produce a radiation signature form the sample, are potentially applicable to high-level radioactive NM analysis if the induced differences appear significantly.
DDA
NRTA
DGA
CHALLENGES / METHODS / IMPLEMENTATION
Flight path: 5m
sample: SF 1 cmt
DEVELOPMET OF ACTIVE NEURON NDA TECHNIQUES
Among the various active neutron interrogation techniques, we chose four techniques given in the table 1, which provide information of a sample from different aspects. The first stage of this study project is basic technological development using low-level radioactive NM samples. To make a system compact, utilization of DT neutron source is considered.
Design study of NDA systems are performed using simulation codes and experimental results. An integrated NDA system for DDA and PGA measurement was constructed at the NUclear fuel Cycle safety Engineering research Facility (NUCEF) in the JAEA Tokai-site. Experimental study of NRTA is carried out at EC-JRC Geel and Kyoto University, and that of DGA at EC-JRC Ispra.
235U : 239Pu
1 : 0
1 : 1
0 : 1
Experimental result of measurements with the DDA part of a DDA-PGA integrated system. The DDA neutron counting time spectra were measured in 600 sec with 100-Hz neutron generation. The moderator thickness used was 6 cm.
Simulated energy-dependent transmission spectra. Neutron pulse width is varied: 10 µs (black), 1 µs (blue), and 0.1µs (red). The vertical positions of the plots are moved for the sake of clarity. The notation of P9, P0, P2, U5, U6, and U8 are relevant to nuclides of 239,240,242Pu, and 235,236,238U, respectively.
High energy delayed gamma-ray spectra measured with PUNITA. The mass ratio of the NM samples were 235U : 239Pu = 1:0 (blue), 1:1 (black ), and 0:1 (red), respectively. The vertical positions of the plots are moved for the sake of clarity.
Table 2. Examples of combinations of NDA techniques
Combination
Measured quantities
Deduced nuclides masses
DDA + DGA
fissile mass
+ ratios of fissile nuclides
U: 235
Pu: 239, 241
HKE + DDA
+ DGA
masses of elements + fissile mass + ratios of fissile nuclides
U: 235, 238; Pu: 239, 241;
sum of the other Pu isotopes
NRTA (10-µs)
masses of nuclides
U: 238; Pu: 239, 240, 242
NETA (10-µs)
+ ratio of fissile nuclides
U: 235, 238,
Pu: 239, 240, 241, 242
Table 1. Four neutron interogation techniquestable
Active Neutron NDA Techniques
Quantification
Differential Die-away Analysis (DDA)
Pulsed neutron interrogation method that measures a time-dependent neutron die-away curve depending on the neutron emission of induced fission reactions.
239Pu-effective mass
Prompt Gamma-ray Analysis (PGA)
Measurement of prompt gamma rays induced by (n, gamma) and the other reactions. Characteristic gamma rays are used to determine nuclides within the sample.
Existence, and qualification/ quantification of specific nuclide
Neutron Resonance Transmission Analysis (NRTA)
Neutron time-of-flight (TOF) measurement, in which nuclide characteristic dips of nuclear reaction resonance energies are observed in an energy-dependent transmission spectrum.
Quantity of each of U/Pu nuclides
Delayed Gamma-ray Analysis (DGA)
Measurement of gamma rays from radioactive nuclei produced by neutron induced fission reactions
Ratio of
235U/239Pu/241Pu
HKE: hybrid k-edge densitometry: Masses of each element are achieved
CONCLUSION
We proposed and have started development of active neutron NDA techniques for measurements of high-level radioactive NM sample.
Basic developments using low-level radioactive samples has been finished. We continue the technological developments for high-level radioactive sample measurements.
A new integrated NDA system, which consists of DDA, PGA, and NRTA systems, will be constructed at NUCEF of JAEA.
ACKNOWLEDGEMENTS
　　　　　　　　　　　　　　　　　　　This technological development was supported by the Japanese government (MEXT: Ministry of Education, Culture, Sports, Science and Technology), subsidiary for “promotion of strengthening nuclear security and the like”.
IAEA Symposium on International Safeguards: Building Future Safeguards Capabilities, 5–8 November 2018, Vienna, Austria