Pulsed photonuclear technology for remote detection of nuclear materials

1. Maxim Karetnikov Pulsed photonuclear technology for remote detection of nuclear materials

2. Outlines • Problems of nuclear materials control. • Features of photonuclear technology for inspections of nuclear materials. • Past and present of photonuclear technologyfor inspections of nuclear materials. • Experimental and numerical study of photonuclear technology for inspection of cargo containers.

3. IAEA INCIDENT AND TRAFFICKING DATABASE (ITDB) 2 Incidents reported to the ITDB involving unauthorized possession and related criminal activities

4. 3 NUCLEAR MATERIALS GENERAL TASKS control containers (sea cargo containers) at ENTRANCE POINT Control of containers (tansport ) at nuclear objectEXIT POINT Minimal quantities of nuclear materials to account for in the state accounting and control system (ОПУК НП 030-05)

5. PERFORMANCE CRITERIA FOR ACTIVE INTERROGATION SYSTEMS (RUSSIAN AUTHORITIES, ANSI N42.41 STANDARD) 4

6. STANDARD SHIPPING CONTAINERS (TUE& FUE) 5 More than 70% of goods are chipped by containers More than 600 million TUE containers processed per year all over the world More than 4 million TUE containers processed per year in Russia

7. Statistics of container loading 6

8. 7 THREE STEPS OF REVEALING THE ILLICIT TRAFFICKING OF NUCLEAR MATERIALS AT CONTROL POINT 1. Detection 2. Localization 3. Identification

9. 1st LIMITATION OF PASSIVE METHODS Highly shielded sources of radiation 8 • Unshielded- sensitivity: 10 g • 5 mm lead- sensitivity: 50 g • 10 mm lead- sensitivity: 200 g U-235, 1 m/sec

10. 2nd LIMITATION OF PASSIVE METHODS Identification of fission materials in legal shipments with radioactive materials 9 Activity of radioisotopes to mask 10 g HEU /1 g Pu

11. 10 3rd LIMITATION OF PASSIVE METHODS Nonradiating sensitive materials

12. 11 ACTIVE METHODS FOR NUCLEAR MATERIALS INSPECTION

13. 12 PHYSICAL PREMISES AND ADVANTAGES OF PHOTONEUTRON TECHNOLOGY High sensitivity; Wide range of detectable materials(fissile and fertile materials, non-radiating materials of nuclear cycle(Li-6, heavy water); Identification of FM against the RM of any reasonable activity; Low induced activation (can be used for repeated control of objects); Practicability (can be realized using existing equipment). For the same mass of fissile material, the rate of photofission by bremsstrahlung produced by 10 MeV, 10 A electron beam is : ≈rate of fissile by 5x1011neutron/sec; 30 million times higher then the rate spontaneous fission of U-235; 500 thousand times higher then the rate of Pu-239 fission.

14. Principles of photonuclear technology 13

15. PROJECTED DEVICE FOR CONTROL OF NUCLEAR MATERIALS 14

16. 15 GAMAS (General Atomic Mobile Assay System) 1972-? 5-10 MeV LINAC 200L barrel interrogation

17. Idaho national engineering and environmental laboratory (USA) 16 Transportable Electron Accelerator (Varitron) Varitron without cover Characteristics: • Energy selectable operation (2 to 12 MeV ) • Variable repetition rate a few Hz to ~ 1kHz • Pulse width few nanoseconds to ~ 4 microseconds

18. 18 Idaho national engineering and environmental laboratory (USA) Detection systems based on Pulsed Photonuclear Assessment (PPA)

19. Idaho national engineering and environmental laboratory (USA) 19 Technology Demonstrations Photon collimator Lead shielding in wood Electron accelerator

20. Idaho national engineering and environmental laboratory (USA) 20 Detection of remote (30 m distance) nuclear materials 30 m

21. Alternative Energies and Atomic Energy Commission (France) 21 Technology Demonstrations

22. CEA (France) 22 Radiography of barrel

23. 24 C-bord project (GB, France, Italy, Germany, Poland, Hungary) Detection of Special Nuclear Material (SNM), uranium, plutonium Strong association between high-energy imaging and photofission techniques Test and validation in first EU photofission port installation based on 9 MeV Linac

24. U-28 LINAC 25

25. Magnetic analyzer of electron beam 26

26. Experimental photonuclear device 27

27. 25 Simulation of gamma-neutron radiation from the container after LINAC pulse Effect- yield of gamma/neutron radiation owning to nuclear materialsBackground yield of gamma/neutron radiation at the lack of nuclear materialsSensitive materials: U-235, Lithium, heavy water

28. Verification of numerical simulation 26

29. Numerical and experimental simulations for optimization of output units of linac 27 Tasks: Choice of material and thickness of converter Choice of filter thickness Choice of material and thickness of collimator Ae- effect (number of detected neutrons from U-238) Ab- number of detected neutrons from output units α-confidence interval p- probability

30. Converter optimization 28 Choice of material Choice of thickness

31. 29 Simulation of gamma-neutron radiation from the container after LINAC pulse Effect- yield of gamma/neutron radiation owning to nuclear materialsBackground yield of gamma/neutron radiation at the lack of nuclear materialsSensitive materials: U-235, Lithium, heavy water

32. STANDARD SHIPPING CONTAINERS 30 • Emptycontainer, • Container fully loaded with material with low atomic number Z – paper of average density 0.5 g/cm 3; • Container fully loaded with material with medium atomic number Z – duralumin (0.5% of iron and 0.5% of silicon) of 0.5 g/cm 3 density; • Container fully loaded with material with large atomic number Z – iron of 0.5 g/cm3 density.

33. Spectrums of gamma-neutron radiation from the container 31

34. Multilayer neutron detector 32 Combined gamma-neutron detector

35. Yield of gamma-neutron radiation from the container (1/electron) 33

36. 34 Assessment of minimal detectable mass of nuclear material Apriory known backgrownd- assume that we know the container loading Unknown background- maximum backround under consideration Sensitive material- U-235

37. Choice of time window for neutrons and gamma-rays recording 35

38. Minimal detectable mass 37 • Calculation of probability of effectηеand backgroundηb, normalized by beam current. • Calculation of effect and background • Dispersion , where • Confidence interval Ib=50 mAτb=1,5 μsF=100 Hzp=0,997 ■ - aluminium▲- iron● - paper▼- empty

39. Minimal Detectable Mass (MDM) 38 Background counting rate 1·10-5 1/(cm2s) Background counting rate 1·10-5 1/(cm2s)

40. Neutron yield vs material location 39 Back wall Center Front wall

41. Recovery of neutron counter after bremsstrahlung pulse 40 20 ms/channel Qn ~ exp(-τD/te); τD = 100 ms→ Qn=0,14Qmax τD =120 msat 10 mGy/pulse τD = 90 ms при 1,6 mGy/pulse τD = 50 ms при 0,13 mGy/pulse

42. High voltage gating at the neutron counter 41 20 ms/channel 10 ms/channel Qn ~ exp(-τD/te); τD = 100 ms→ Qn=0,14Qmax Qn ~ exp(-τD/te); τD = 20 ms → Qn=0,7·Qmax

43. 43 U-238 analysis by prompt neutrons The data are normilized by mass of U-238 and electron beam charge Ibtin mС Beryllium analysis by prompt neutrons U-238 analysis by delayed neutrons

44. Potentially harmful effects at photonuclear analysis 42 Radiation damage of semiconductors : 102– 105Gy; 104 – 109Gy/s; modification of polymers: 103 – 106Gy. Damage of optical devicse: 105 – 106Gy.Modification of organic optical devices: 104 – 105 Gy.Photographic films, 0,01 Gy –blackening~ 1. Induced activity: less than exempt quantity.

45. Summary 43 • Photonuclear technology provides detection of several- several dozens grams of nuclear materials in the sea cargo containers shielded by metal and organic materials. • Optimal electron beam energy when recording prompt neutrons: 8 ÷ 9 MeV. • Optimal electron beam energy when recording delayed neutrons ~16 MeV (generation of precursors of delayed neutrons), in , threshold 15.9 MeV. • Nuclear materials shielded by organic materials can be detected by secondary 2.2 MeV gamma-rays from thermalized neutron capture by hydrogen nuclear. • Sensitivity strongly depends on electron beam energy fluctuation (Minimal detectable mass increase by 3-10 when fluctuation increase by 10%). • Photonuclear technology harmless for container content, and it can be used many times per year.