Developm ent of Active Neutron NDA System Yosuke Toh Nuclear - - PowerPoint PPT Presentation

JAEA 2 0 1 8 Sym posium on Nuclear Data

Developm ent of Active Neutron NDA System

Yosuke Toh

Nuclear Science and Engineering Center Japan Atomic Energy Agency

JAEA

Collaborators

This research w as im plem ented under the subsidiary for nuclear security prom otion of MEXT.

• Y. Toh 1, A. Ohzu 1, H. Tsuchiya 1, K.Furutaka 1,F. Kitatani1,
• M. Kom eda 1, M. Maeda 1, M. Kureta 1, M. Koizum i1, M. Seya 1,
• J. Heyse 2, C. Paradela 2, W . Mondelaers2, P. Schillebeeckx 2
• T. Bogucarska 3, J. Crochem ore 3, G. Varasano3, K. Abbas3
• B. Pedersen 3

1 Japan Atom ic Energy Agency 2 Joint Research Centre – Geel 3 Joint Research Centre – I spra

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Outline

2 Active neutron NDA techniques 3 Developm ent of Active-N @ NUCEF 4 Sum m ary 1 Objectives

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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 PUNI TA @ I spra GELI NA @ Geel

Experimental facilities

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DT neutron generator

Neutrons Neutrons can lead to nuclear fission and neutron capture reactions w hich produce gam m a-rays and neutron.

DDA （Differential Die- aw ay Analysis） PGA （Prom pt Gam m a- ray Analysis） NRTA （Neutron Resonance Transm ission Analysis） DGA （Delayed Gam m a- ray Analysis） Nuclear fission Neutron capture reaction

U

N

2 3 9Pu effective

Ratio 2 3 5U/ Pu Specific Nuclei of SNA,MA Explosive,Neutron poison

Excited state Stable nucleus Unstable nucleus

Prom pt gam m a-ray Delayed gam m a-ray Fission neutron

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Active neutron NDA techniques

Excited state Stable nucleus Stable nucleus

2 × 1 0 9 neutrons/ s 1 4 MeV

Sodern Genie3 5

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Ideal concept design of NDA system

A D-T Pulsed Neutron S

• urce

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

Transmit t ed Neut rons

Neutron Resonance Transmission Analysis

（NRTA）

S amples to be Verified

Neutron reflector Neutron S hielding and Transportation Gamma-ray Detectors

Monte Carlo simulation (PHITS, MVP, MCNP)

DDA PGA

（DDA,PGA,NRT RTA,DGA） Radi diati tion

• n

shie ields for r licens censing ng pr proc

• cess

Neut eutron n reflector

• r

Neut eutron n moder erator Neut eutron n & gamma-ray shie ields Collim limator Correc ection n met etho hods Neut eutron n flux ux distrib ibutio ion

Development of Active-N(DDA,PGA)

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Active-N-II

Dev evel elopmen ents of det etect ectors

Polyethylene

SUS Detector bank DT neutron source Air Air

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Simulation studies of DDA and PGA

Sam ple 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)

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

200L Drum Shields DT neutron source Detector bank Interrogation neutron Fission neutron

Neutron counts 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

• f neutrons from the sample.

0% 100% 200% 300% 400% 500% 0.01g 0.1g 0.5g 1g 5g 10g 15g

3cm 4cm 5cm 6cm 7cm 8cm 9cm 10cm

Optimization of moderator thickness

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DDA DDA：Simu mulation sp spectra Op Optimu mum t m thickn kness ss 5cm 5cm～6cm 6cm

239 239Pu

Pu

Rela lativ ive d detectio ion efficienc ency （for 3cm cm） Ela lapsed tim ime (μsec ec) Neut utron c n coun unts Moderator thickness ss

Moderator Sam ample Det etect ector bank nk DT DT neut neutron s n sour urce ce

1.E+0 1.E+2 1.E+4 1.E+6 1.E+8 1.E+10

200 400 600 800 1000

Pu-239 15.0g Pu-239 10.0g Pu-239 5.0g Pu-239 1.0g Pu-239 0.5g Pu-239 0.1g Pu-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

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Neutron Resonance Transmission Analysis（NRTA）

240Pu 242Pu

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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 [cm] The fluxes of neutrons and γ rays

SUS

Polyet hylene

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)

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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

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Nuclear data of Radioactive Isotopes

JENDL DL-4. 4.0

NRTA TA (and nd NRCA) ca can’t n’t be e us used ed to mea easur ure Se-79 79

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

ー Exp. ー Cal.

NRTA RTA s spect ectra of f Cu-63 63

Large d e discr crep epanc ncy

NRTA measurements of Cu-63

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Optim ization

• f Γn

Γn ＝0.59±0.02eV Γn ＝ 0.899±0.005eV

ー Exp. ー Cal.

NRTA measurements of Cu-63

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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

W P：W hite phosphorus m unitions VX：VX gas ( nerve agent) GB：Sarin ( nerve agent) HE：High Explosive L：Lew isite gas H：Sulfur m ustard gas CG：Phosgene CK：cyanogen chloride HN：Nitrogen m ustard gas FM：Sm oke

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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)

1 4N, 1 0 ,8 2 9 keV

53Cr, 8 8 8 4 keV

5 6Fe, 7 6 3 1 + 7 6 4 6 keV

w / : 3 3 0 m in. w / o : 1 4 0 m in.

Detection of Nitrogen gammas (HE)

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Summary

Active neutron NDA techniques have been studied and im proved in JRC-JAEA collaboration: AS-7 . Nuclear data is still lacking. Developm ents of Active-N( DDA,PGA) has been com pleted successfully in Phase I and Phase I I has started.