Active Interrogation of SNMs by use of IEC Fusion Neutron Generator

Transcription

1 Active Interrogation of SNMs by use of IEC Fusion Neutron Generator Kai Masuda 1, T. Masawa 2, Y. Yakahashi 2, T. Yagi 2, R. Nakamatsu 1, S. Fushimoto 3 1 Inst. Advanced Energy, Kyoto Univ. 2 Research Reactor Inst., Kyoto Univ. 3 Pony Industry Co. Ltd. R&D Program for Implementation of Anti-Crime and Anti-Terrorism Technologies for a Safe and Secure Society promoted by Japan Science and Technology Agency

2 Talk Outine Introduction Background Project overview Neutron-Based Rapid Screening System System layout container trucks, IECs, detectors, Pulsed IEC and HV power supply Detection Methods & Exp. Results Delayed Neutron Noise Analysis (DNNA) Threshold Energy Neutron Analysis (TENA) Concluding Summary & Plans 1

3 Nuclear Terrorism Threats Conventional gun-type nuclear weapon: kg of 235 U 3.14m 2

4 Nuclear Terrorism Threats Conventional gun-type nuclear weapon: kg of 235 U 3.14m Modern tactical nuclear weapon: kg of 239 Pu 2

5 Nuclear Terrorism Threats Conventional gun-type nuclear weapon: kg of 235 U 3.14m Modern tactical nuclear weapon: kg of 239 Pu 235 U Hiroshima-type is more troublesome. 2

6 Nuclear Terrorism Threats Conventional gun-type nuclear weapon: kg of 235 U 3.14m Modern tactical nuclear weapon: kg of 239 Pu 235 U Hiroshima-type is more troublesome. passive detection is impossible unlike 239 Pu Passive Gamma-ray detectors Effective to 239 Pu Pony Industry Co. Ltd. 2

7 Nuclear Terrorism Threats Conventional gun-type nuclear weapon: kg of 235 U 3.14m Modern tactical nuclear weapon: kg of 239 Pu 235 U Hiroshima-type is more troublesome. passive detection is impossible unlike 239 Pu easy to make w/o test bans assembling in the target nation is possible 2

8 Nuclear Terrorism Threats Conventional gun-type nuclear weapon: kg of 235 U 3.14m Modern tactical nuclear weapon: kg of 239 Pu 235 U Hiroshima-type is more troublesome. passive detection is impossible unlike 239 Pu easy to make w/o test bans assembling in the target nation is possible identification by shape is not effective enough 2

9 Nuclear Terrorism Threats Conventional gun-type nuclear weapon: kg of 235 U 3.14m Modern tactical nuclear weapon: kg of 239 Pu 235 U Hiroshima-type is more troublesome. passive detection is impossible unlike 239 Pu easy to make w/o test bans assembling in the target nation is possible identification by shape is not effective enough Transportation of tens kg of 235 U air cargo, land transportation, spy ship, sea container. 2

10 Megaports Initiative (2007) Mandatory SNM screening of all US-bound containers at their port of origin from Photo by Gunnar Ries 20ft container 8 ft x 8 ft x 20 ft 400 containers / day from Yokohama 3

11 Megaports Initiative (2007) Mandatory SNM screening of all US-bound containers at their port of origin from Photo by Gunnar Ries 20ft container 8 ft x 8 ft x 20 ft 400 containers / day from Yokohama It has been delayed 2x2 years (until 2016), due to lack of SNM detection system. 3

12 Megaports Initiative (2007) Mandatory SNM screening of all US-bound containers at their port of origin from Photo by Gunnar Ries 20ft container 8 ft x 8 ft x 20 ft 400 containers / day from Yokohama It has been delayed 2x2 years (until 2016), due to lack of SNM detection system. Very rapid (2 min/container) inspection system is required. JPN gov. will setup 2-3 central seaports. Our proposal is to built SNM screening facilities in those central seaports. 3

13 Project Overview 2. X-ray image 3. LCS γ-ray beam for isotope identification 10 min / point 1. Neutron-based system 6m 400 containers / day 4

14 Project Overview Scanning whole volume impossible. 2. X-ray image 3. LCS γ-ray beam for isotope identification 10 min / point 1. Neutron-based system 6m 400 containers / day 4

15 Project Overview Pony Industry Co. Ltd. 1. Neutron-based system 3. LCS γ-ray beam for isotope identification 10 min / point 2. X-ray image for determination of point(s) of interest 6m 400 containers / day 4

16 Project Overview 1. Neutron-based system for rapid screening false alarm rate < 10% 2 min. per container 3. LCS γ-ray beam for isotope identification 10 min / point 2. X-ray image for determination of point(s) of interest 40 6m containers / day 4

17 Project Overview Proof-of-principle, reduced-scale prototype experiments, & scale-up design 1. Neutron-based system for rapid screening false alarm rate < 10% 2 min. per container 3. LCS γ-ray beam for isotope identification 10 min / point 2. X-ray image for determination of point(s) of interest 40 6m containers / day 5-year R&D from FY2010 R&D budget: 5.5M$ Estimated cost: 26.5M$ 4

18 Neutron-Based Screening Facility 2 containers / 10 min 5 min for neutron-irradiation/detection, and 5 min for replacement of container trucks. container truck IECs driver 10 m 5

19 Neutron-Based Screening System Two container trucks are inspected simultaneously with Three pulsed DD-IECs (10 8 n/sec), He detectors (1 dia., 1m length) or more BF 3 detectors, 54 NE213 detectors (5 dia., 4 length) or fewer TMFDs. Thermal Neutron Detectors Fast Neutron Detectors Poly-Roof DD IECs Poly-Wall Pulsed HV Power Supplies 6

20 Newly Developed Pulsed IEC All in one grounded tank Low EM noise emission Dual 200 kv switches Quick pulse fall-off cathode anode IEC chamber 3-stage HV feedthrough DC PS capacitor switches oil tank (7000L) 7

21 Typical Pulse Shapes of V, I and NPR voltage [kv] Pa(D 2 ) time [μsec] current [A], neutron count rate [a.u.] Details will be given tomorrow. 8

22 Experimental Pulsed Neutron Yield Experimental tests were carried out with two pulsed HV PSs. 100kV-20A PS will be used for demo. because of transportation/ space limitations and oil/radiation regulations in KUCA facility where 235 U can be used. norm. neutron yield per pulse charge [n/c/pa] ~10 9 n/sec(peak) with 20A 100kV-20A PS 200kV-05A PS peak discharge voltage, V peak [kv] Details will be given tomorrow. 9

23 incident neutrons Neutron-In Neutron-Out Detection of SNMs A principal challenge is to distinguish the secondary neutrons from the probing neutrons. HEU delayed neutrons (<1%) Easier approach, but much less signals. cf. Delayed Neutron Analysis (DNA) probing neutrons prompt delayed prompt neutrons (>99%) Much more plentiful, t but need to separate out from probing neutrons cf. Differential Die-Away Analysis (DDAA) Either DNA or DDAA requires very intense NGs (DT mandatory). 10

24 incident neutrons Neutron-In Neutron-Out Detection of SNMs A principal challenge is to distinguish the secondary neutrons from the probing neutrons. HEU delayed neutrons (<1%) Easier approach, but much less signals. cf. Delayed Neutron Analysis (DNA) probing neutrons prompt delayed prompt neutrons (>99%) Much more plentiful, t but need to separate out from probing neutrons cf. Differential Die-Away Analysis (DDAA) Either DNA or DDAA requires very intense NGs (DT mandatory). New techniques are being developed. 1. Delayed Neutron Noise Analysis (DNNA) 2. Threshold Energy Neutron Analysis (TENA) 10

25 What is Neutron Noise? neutron noise example observed in KU critical assembly (KUCA) neutron count rate, n(t) [cps] fluctuation time avg. time [sec] 11

26 Neutron Noise Contains Signature of Fission Chain Reactions neutron noise example observed in KU critical assembly (KUCA) neutron count rate, n(t) [cps] gate width, t fluctuation, time avg., σ n() t () t time [sec] Y ( t) σ = n 2() t () t 1 Y( ) = 0 random neutrons (Poisson distribution) Y( ) > 0 correlated neutrons 11

27 Basic Neutron Noise Analysis (NNA) Well developed method in fission reactor physics field. Characterizes neutron multiplication factor due to fission chain reactions. neutron noise example observed in KU critical assembly (KUCA) neutron count rate, n(t) [cps] gate width, t fluctuation, time avg., σ n() t () t time [sec] Y ( t) σ = n 2() t () t 1 Y( ) = 0 random neutrons (Poisson distribution) Y( ) > 0 correlated neutrons 11

28 Delayed Neutron Noise Analysis (DNNA) n(t) neutron count rate in detector w/o HEU w/ HEU time, t incident neutron pulses from IECs 12

29 Delayed Neutron Noise Analysis (DNNA) n(t) neutron count rate in detector w/o HEU w/ HEU U d U U d time, t U-235 fission fragment delayed neutron precursor probing neutrons from IEC delayed neutrons neutrons from chain reactions 13

30 Delayed Neutron Noise Analysis (DNNA) n(t) neutron count rate in detector w/o HEU w/ HEU d U d U U d time, t U-235 fission fragment delayed neutron precursor d probing neutrons from IEC delayed neutrons neutrons from chain reactions 13

31 Delayed Neutron Noise Analysis (DNNA) n(t) neutron count rate in detector w/o HEU w/ HEU d U d U U d time, t U-235 fission fragment delayed neutron precursor d probing neutrons from IEC U U delayed neutrons neutrons from chain reactions 13

32 Delayed Neutron Noise Analysis (DNNA) n(t) neutron count rate in detector w/o HEU w/ HEU time, t U-235 fission fragment elayed neutron precursor probing neutrons from IEC delayed neutrons neutrons from chain reactions13

33 Delayed Neutron Noise Analysis (DNNA) Y ( t) σ = n 2() t () t 1 Y( ) = 0 random neutrons (Poisson distribution) Y( ) > 0 neutrons from fission chain reactions n(t) dump dump dump w/o HEU w/ HEU time, t U-235 fission fragment elayed neutron precursor probing neutrons from IEC delayed neutrons neutrons from chain reactions13

34 Delayed Neutron Noise Analysis (DNNA) Y ( t) σ = n 2() t () t 1 Y( ) = 0 random neutrons (Poisson distribution) Y( ) > 0 neutrons from fission chain reactions n(t) dump dump dump w/o HEU w/ HEU Y (t) dump dump dump time, t w/o HEU w/ HEU time, t 14

35 DNNA Experimental Setup in KUCA p p p p p p p p p H5 H1 H2 H3 H4 H6 p H Detector 3 He: 1 dia., 20cmL, 5atm p p p F F p p F F p F p HEU 10 Poly U-235:1.3 kg (k eff = 0.12) NPR (DT):~10 5 n/sec p p p p T-Target 10 μsec, 10 Hz p p p p p D-Beam ROI in DNNA: msec HEU 15

36 DNNA Experimental Results Clear difference in Y(t) was seen from BG w/o HEU. w/ HEU w/o HEU 16

37 Threshold Energy Neutron Analysis (TENA) A significant portion of the fission neutrons is above DD neutron energy. 0.4 χ(e) [MeV -1 ] fission spectrum 核分裂中性子スペクトル DD 中性子源から発生する中性子のエネルギー 2.45 MeV neutron energy from DD source (2.45 MeV) 30% Energy [MeV] 17

38 Threshold Energy Neutron Analysis (TENA) A significant portion of the fission neutrons is above DD neutron energy. Use of DD neutron source is mandatory. Neither DT nor RI source is applicable. 0.4 χ(e) [MeV -1 ] fission spectrum 核分裂中性子スペクトル DD 中性子源から発生する中性子のエネルギー 2.45 MeV neutron energy from DD source (2.45 MeV) 30% Energy [MeV] 17

39 Threshold Energy Neutron Analysis (TENA) A significant portion of the fission neutrons is above DD neutron energy. Use of DD neutron source is mandatory. Neither DT nor RI source is applicable. Either dc or pulsed source is applicable. 0.4 χ(e) [MeV -1 ] fission spectrum 核分裂中性子スペクトル DD 中性子源から発生する中性子のエネルギー 2.45 MeV neutron energy from DD source (2.45 MeV) 30% Energy [MeV] 17

40 TENA Experimental Setup DD IEC (DC) Cf-252 DD-IEC 150cm Cf cm detector + shielding (Pb, poly) NE213 liquid scintillator + 5cm Pb + 10cm Ploy X/γ-rays are rejected, making use of induced pulse shape difference. DD IEC 0.1, 1.0, 2.0, 3.0x10 7 [n/sec] Cf x10 4 [n/sec] 18

41 TENA Experimental Results Clear difference between Green (signal + BG) and Black (BG only) is seen above 2.45 MeV. Count Cps rate [cps] MeV neutrons from DD fusion DD only (BG) Fission only Fission + DD (BG) DD only Cf only DD + Cf MCA channel Channel (neutron energy) 19

42 TENA Experimental Results Clear difference between Green (signal + BG) and Black (BG only) is seen above 2.45 MeV. BG counts above 2.45 MeV are seen due to X/γ-rays and pileup of less energetic neutrons. Count Cps rate [cps] MeV neutrons from DD fusion DD only (BG) Fission only Fission + DD (BG) DD only Cf only DD + Cf MCA channel Channel (neutron energy) 19

43 TENA Experimental Results (Contd.) BG count rate above 2.45 MeV is seen to increase nonlinearly as increase of incident DD neutrons (and X-rays) from IEC. BG count rate above 2.45 MeV [cps] 0.1 Y = (5.8E-06) X 2 + (6.8E-04) X + (1.1E-02) DD-IEC NPR 3.0 x 10 7 n/sec BG count rate below 2.45 MeV [cps] 20

44 Estimation of Required Detection Time Two container trucks are inspected simultaneously with Three pulsed DD-IECs (10 8 n/sec), He detectors (1 dia., 1m length), and 54 NE213 detectors (5 dia., 4 length). Thermal Neutron Detectors Fast Neutron Detectors Poly-Roof Estimation made based on the exp. results and MCNP6 simulations. DD IECs Poly-Wall Pulsed HV Power Supplies 21

45 Detection Time for 1kg HEU Assumption: Nothing in the container except for 1-kg HEU. 8ft (2.4m) 8ft (2.4m) NE (1) (5) 1 IEC (1) (5) 0.8 He-3 He-3 detection time by DNNA(TENA) [min] corner: 5.8 min 22

46 Tensioned Metastable Fluid Detector (TMFD) Developed by Prof. Taleyarkhan group in Purdue Univ. See for example, R.P. Taleyarkhan, et al., Nuclear Engineering and Design 238 (2008) Centrifugal TMFD Acoustic TMFD Blind to X/γ-rays. Blind to neutrons below a threshold energy. The threshold neutron energy variable. ~90% efficiency with 10cm x 10cm volume. Directional detection by ATMFD. 23

47 Concluding Summary & Plan Nondestructive screening as fast as 2 min/container is required in order not to block sea container distribution. Experiments have been made for the two neutronbased methods, namely DNNA and TENA. An inspection facility has been designed, which can handle two container trucks per 10 min, including mandatory 5 min for trucks replacement. 5 x5 x5 -scale tests are planed Dec 2014 Feb 2015 by use of a single IEC, reduced number of detectors and U-235 (natural uranium). We also plan to test a novel fast neutron detector, TMFD, which is ideal for TENA because it is blind to X/γ-rays and neutrons below 2.45 MeV. 24