JAEA 2018 Symposium on Nuclear Data

Development of Active Neutron NDA System

Yosuke Toh

Nuclear Science and Engineering Center Japan Atomic Energy Agency

JAEA

Collaborators

This research was implemented under the subsidiary for nuclear security promotion of MEXT.

Y. Toh1, A. Ohzu1, H. Tsuchiya1, K.Furutaka1,F. Kitatani1, M. Komeda1, M. Maeda1, M. Kureta1, M. Koizumi1, M. Seya1, J. Heyse2, C. Paradela2, W. Mondelaers2, P. Schillebeeckx2

T. Bogucarska3, J. Crochemore3, G. Varasano3, K. Abbas3 B. Pedersen3

1 Japan Atomic Energy Agency 2 Joint Research Centre – Geel 3 Joint Research Centre – Ispra

JAEA

Outline

2 Active neutron NDA techniques

3 Development of

Active-N @ NUCEF

4 Summary

1 Objectives

JAEA

Action Sheet -1 (2012 - 2015)

JRC-JAEA Collaboration

Neutron Resonance Densitometry (NRD) For characterization of debris of melted fuel

Action Sheet -7 (2015 – 2017) Developments of active neutron NDA techniques for Nuclear Non-Proliferation, Security and Safety

JRC-JAEA Collaboration:AS-7 JAEA

Investigate and demonstrate active neutron NDA technologies to quantify special nuclear materials and other elements in the presence of high radioactive materials

TRP-PCDF @ Tokai

NUCEF-BECKY @ Tokai

PUNITA @ Ispra

GELINA @ Geel

Experimental facilities JAEA

DT neutron generator

Neutrons

Neutrons can lead to nuclear fission and neutron capture reactions which produce gamma-rays and neutron.

DDA （Differential Die-away Analysis）

PGA （Prompt Gamma-ray Analysis）

NRTA （Neutron Resonance Transmission Analysis）

DGA （Delayed Gamma-ray Analysis）

Nuclear fission

Neutron capture reaction

U

N

239Pueffective

Ratio 235U/Pu

Specific Nuclei of SNA,MA

Explosive,Neutron poison

Excited state

Stable nucleus

Unstable nucleus

Prompt gamma-ray

Delayed gamma-ray

Fission neutron

JAEA

Active neutron NDA techniques

Excited state

Stable nucleus

Stable nucleus 2×109

neutrons/s

14MeV

Sodern Genie35

JAEA

Ideal concept design of NDA system

A D-T Pulsed Neutron Source

Differential Die-away Analysis（DDA）

Delayed Gamma-ray Analysis （DGA）

Prompt Gamma-ray Analysis （PGA）

Neutron Detector Bank

A Li-glass Neutron Detector

（Inside）

Gamma-ray Detector

Transmitted Neutrons

Neutron Resonance Transmission Analysis

（NRTA）

Samples to be Verified Neutron reflector

Neutron Shielding and Transportation

Gamma-ray Detectors

Monte Carlo simulation (PHITS, MVP, MCNP)

DDA

PGA

（DDA,PGA,NRTA,DGA）

Radiation shields for licensing process

Neutron reflector

Neutron moderator Neutron & gamma-ray shields

Collimator Correction methods

Neutron flux distribution

Development of Active-N(DDA,PGA) JAEA

Active-N-II

Developments of detectors

Polyethylene

SUS

Detector bank DT neutron source

Air Air

JAEA

Simulation studies of DDA and PGA

Sample

Simulation studies for prototype system (Active-N) which can measure DDA and PGA have been performed by MCNP (MVP and PHITS).

Differential Die-away Analysis(DDA)

JAEA

Differential Die-Away (DDA) is an active neutron interrogation technique

200L Drum

Shields

DT neutron source Detector bank

Interrogation neutron

Fission neutron

Neutr

on c

ounts

Elaspsed time

Fission neutron（∝ fissile）

Interrogation neutron

Neutron die-away time

1/e

Neutron signal counts DDA measurements

In DDA, a neutron detector measures the time-dependent decay of neutrons from the sample.

0%

100%

200%

300%

400%

500%

0.01g 0.1g 0.5g 1g 5g 10g 15g

3cm4cm5cm6cm7cm8cm9cm10cm

Optimization of moderator thickness

JAEA

DDA：Simulation spectra

Optimum thickness 5cm～6cm

239Pu

Rela

tive

dete

ctio

n

eff

icie

ncy

（fo

r 3cm

）

Elapsed time (μsec)

Neutr

on c

ount

s

Moderator thickness

Moderator

Sample

Detector bank DT neutron source

1.E+0

1.E+2

1.E+4

1.E+6

1.E+8

1.E+10

0 200 400 600 800 1000

Pu-239 15.0g Pu-239 10.0gPu-239 5.0g Pu-239 1.0gPu-239 0.5g Pu-239 0.1gPu-239 0.01g blank

U & Pu

MA

Each nuclide has resonances at specific energies.

Resonances can be used to identify & quantify SNM and MA.

Total cross sections(JENDL-4)

Pulsed Neutron

Sample Neutron Detector

Transmitted neutrons

JAEA

Neutron Resonance Transmission Analysis（NRTA）

240Pu 242Pu

JAEA

Simulation model of a compact NRTA system

DT neutron source

Neutron detector (6Li-glass detector)

Sample

Pb

Flight path length: 5 m

Neutrons

Polyethylene + Stainless steel (SUS) Boron-Polyethylene + Pb

Air Polyethylene Boron-Poly. SUS Al

y [c

m]

The fluxes of neutrons and γ rays

SUS

Polyethylene

Neutron and γ ray fluxes: 1cm or 3cm

30 GWd/t spent fuel (t 1cm)

240Pu (1.03 eV)

242Pu (2.6 eV)

238U (6.7 eV)

Electron linac : 1 us

238Pu (18.6 eV)

241Pu (4.28 eV)

235U (8.76 eV)

239Pu (0.3 eV)

DT tube : 10 us

All Pu, 235U and 238U can be measured with a pulse width (<1 us)

JAEA

Effects of a pulse width of a neutron beam

239Pu, 240Pu, 242Pu and 238U can be measured with DT tube

238U (6.7 eV)

Pulse widths

JAEA

Nuclear data of Radioactive Isotopes

JENDL-4.0

NRTA (and NRCA) can’t be used to measure Se-79

Se-79 is important for long-term safety assessment of a geological repository

ー Exp. ー Cal.

NRTA spectra of Cu-63

Large discrepancy

NRTA measurements of Cu-63 JAEA

Optimization of Γn

Γn ＝0.59±0.02eV

Γn ＝0.899±0.005eV

ー Exp. ー Cal.

NRTA measurements of Cu-63 JAEA

C/E = Experiment (Areal density) Calculation (Areal density)

New Γn ＝0.899±0.005eV Old Γn＝0.59±0.02eV

<±2%

C/E

Decision tree of HE, CW, n poisons WP：White phosphorus munitions VX：VX gas (nerve agent) GB：Sarin (nerve agent) HE：High Explosive L：Lewisite gas

H：Sulfur mustard gas CG：Phosgene CK：cyanogen chloride HN：Nitrogen mustard gas FM：Smoke

JAEA

Active-N system can detect all of these elements.

High S/N ratio in the high energy region

• Capture cross section small (sg(25.3meV)~80mb) • Includes high-energy gamma rays (e.g. 10,829keV)

14N, 10,829keV

53Cr, 8884keV

56Fe

, 7

63

1+

76

46

keV

w/ : 330 min. w/o : 140 min.

Detection of Nitrogen gammas (HE) JAEA

JAEA

Summary

Active neutron NDA techniques have been studied and improved in JRC-JAEA collaboration: AS-7.

Nuclear data is still lacking.

Developments of Active-N(DDA,PGA) has been completed successfully in Phase I and Phase II has started.