CN1196797A - Method and apparatus for detecting and identifying fissionable material - Google Patents
Method and apparatus for detecting and identifying fissionable material Download PDFInfo
- Publication number
- CN1196797A CN1196797A CN96197052A CN96197052A CN1196797A CN 1196797 A CN1196797 A CN 1196797A CN 96197052 A CN96197052 A CN 96197052A CN 96197052 A CN96197052 A CN 96197052A CN 1196797 A CN1196797 A CN 1196797A
- Authority
- CN
- China
- Prior art keywords
- neutron
- bremstrahlen
- detector
- particle accelerator
- fissioner
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000000463 material Substances 0.000 title claims abstract description 29
- 238000000034 method Methods 0.000 title claims abstract description 18
- 230000003111 delayed effect Effects 0.000 claims abstract description 18
- 230000004907 flux Effects 0.000 claims abstract description 16
- 239000002245 particle Substances 0.000 claims abstract description 14
- 238000001514 detection method Methods 0.000 claims description 8
- 230000005855 radiation Effects 0.000 claims description 4
- 229910000831 Steel Inorganic materials 0.000 claims description 2
- 239000010959 steel Substances 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 238000007689 inspection Methods 0.000 abstract description 4
- 230000004992 fission Effects 0.000 description 10
- 239000012634 fragment Substances 0.000 description 4
- ZSLUVFAKFWKJRC-IGMARMGPSA-N 232Th Chemical compound [232Th] ZSLUVFAKFWKJRC-IGMARMGPSA-N 0.000 description 2
- 230000005461 Bremsstrahlung Effects 0.000 description 2
- 229910052778 Plutonium Inorganic materials 0.000 description 2
- 229910052776 Thorium Inorganic materials 0.000 description 2
- 229910052770 Uranium Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 2
- 230000006378 damage Effects 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Images
Classifications
-
- G01V5/281—
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T3/00—Measuring neutron radiation
-
- G01V5/234—
Abstract
The invention relates to a method and apparatus for detecting and identifying fissionable materials from among other transported goods, in which method the material (4) under inspection is irradiated with bremmstrahlung (2) generated by a linear particle accelerator (1). According to the invention, a delayed neutrons flux emitted from the material (4) under inspection by means of bremmstrahlung (2) is detected with at least one neutron detector (7) after interrupting the bremmstrahlung (2), and if essential changes occur in the neutron flux, the position of the material (4) in relation to the detector is determined. After inspecting the whole bulk of goods, the material (4) is returned to the position determined according to the change in the neutron flux in relation to the detector (7), and in this determined position the material (4) is again irradiated with bremmstrahlung (2) in order to identify the material generating the neutron flux, and at least one neutron detector (7) is used for detecting the delayed neutrons emitted from the fissionable material, in order to identify the fissionable material (6) in question.
Description
The present invention relates to a kind of the detection and the method and apparatus of differentiating fissioner, in the method, the intensity of the neutron irradiation of fissioner emission is measured with neutron detector.
Fissioner (for example plutonium, uranium and thorium) can be used to fission reaction, and this moment, the heavy nucleus of atom was split into two or more parts, and this takes place with the neutron bombardment atomic nucleus time usually.Usually, neutron or gamma-rays emission take place to be accompanied by often in fission.Because fission reaction includes huge energy, use fissioner can cause surprising destruction improperly, so the non-control of fissioner and illegal distribution are extreme dangerous to surrounding environment.The illegal transportation of fissioner from a country to another country normally is contained in to be carried out the van container.A spot of fissioner is easy to conceal in container.Such container with the naked eye checks usually, and in this case, very difficultly checks out a small amount of fissioner.
In order automatically to check container and to detect and conceal in object wherein, developed the method for utilizing straight line particle accelerator (as electron accelerator) to produce bremstrahlen already and investigated the article of container the inside, and target is moved to form the picture that container includes object with respect to the inspection device of target.
The objective of the invention is to eliminate some shortcoming of prior art, realization is applicable to the method and apparatus that detects and differentiate fissile material (as plutonium, uranium and thorium), and that this method and apparatus has utilized is that bremstrahlen that the straight line particle accelerator produces and this bremstrahlen produce, from the delayed neutron emission of fissioner.The basic new feature of the present invention can obviously be found out from appended patent claims.
According to the present invention,, used the high energy bremsstrahlung source that runs on 7-10MeV in order to detect and differentiate fissioner; The checked target of radiation directive that is produced thus is as the container of transportation.When bremstrahlen bombardment fissioner, photon and nuclear reacting to each other are taken place between radiation and material, neutron ejection takes place subsequently.Photoneutron reaction and light fission reaction take place when photon and atomic nucleus react to each other, and it is characterized in that the prompt neutron emission.In each prompt neutron that reacts to each other emission, neutron of photoneutron reaction emission, 2.5 neutrons of light fission reaction emission.The further result of light fission reaction produces the radioactive fission fragment, and wherein the beta disintegration energy that comprised of part fragment can surpass the neutron-binding energy in the atomic nucleus.This beta disintegration energy further causes the delayed neutron emission.The fission fragment of emission delayed neutron is called precursor.Fissioner has the photonuclear reaction threshold energy of minimum band neutron ejection.The reaction cross-section of photonuclear reaction and light fission reaction is very big for fissioner, and for example for the energy of E=8MeV, its value is respectively about 100 and 300mb (millibarn).
According to the present invention, to being detected with at least one neutron detector from the fissioner emission and the delayed neutron emission of passing the bremstrahlen district.According to the present invention, used neutron detector preferably for example fills
3He or
10The neutron detector of B, or to the scintillation detector of neutron sensitivity.Neutron detector preferably is positioned in shadow positions by means of collimating apparatus, so bremstrahlen can be blocked basically to the primary radiation of detector.Neutron detector is used to detect delayed neutron especially, and this is because delayed neutron is only intrinsic by fissioner.The yield of delayed neutron is about 1% of prompt neutron, but because exposure duration wants much longer and the neutron background is very low, the sensitivity of detection is sufficiently high.
According to the present invention, used straight line particle accelerator preferably runs on pulse mode.So the frequency range of bremstrahlen pulse is existed, for example, 50-500Hz, and the pulse width of bremstrahlen is about 1.5 μ s.Be spaced apart 2.000-20.000 μ s between two subsequent pulses so.If do not consider in order to stop bremstrahlen neutron detector to be installed in the shadow region of collimating apparatus, then the bremstrahlen pulse of scattering will produce ionization in neutron detector on the accelerator shielding chamber.Consequently the high-amplitude pulse of the about 10 μ s of width appears in the output of detection system.At the high-amplitude impulse duration, the detection of neutron is impossible, so the present invention has used the selection of time unit.The operation of this lockable detection system in selection of time unit, and behind the bremstrahlen end-of-pulsing, reopen time window.The width of time window is in the scope of 150-200 μ s.
According to the present invention, the whole volume that is examined material (as delivery container) is with bremstrahlen irradiation in addition.If detect the substantial variation of delayed neutron flux, then the corresponding material of this variation position is carried out definite.After the whole volume of material was by irradiation, material was sent back to the position that changes corresponding to neutron.On this position with bremstrahlen once more one segment length's time of irradiation (30-60s) to differentiate problematic material.For carrying out the discriminating of fissioner, bremstrahlen is interrupted earlier, measures the delayed neutron flux then at least one minute.
Below the present invention is explained in more detail, quotes following accompanying drawing for this reason:
Figure 1 shows that the local side-looking xsect of a preferred embodiment of the present invention.
The neutron detection system time selected cell operation block diagram of Fig. 2 for linking to each other with Fig. 1 embodiment.
Fig. 3 is by means of the operation logic of time domain coordinate key diagram 2 selection of time unit.
Press Fig. 1, straight line particle accelerator 1 produces bremsstrahlung beam 2, and this bundle passes the slit on the collimating apparatus 3, irradiation container 4.Point scintillation detector 5 is used to produce the picture of object in the container 4 with imaging processor.If contain fissioner 6 in the container 4, then when fissioner fell into the irradiated site of bremstrahlen 2, fissioner 6 can produce the prompt neutron emission.This neutron detects with filling He detector 7, and the molal weight of He is 3.For the power spectrum that softening neutron produces, detector 7 is immersed in and contains in the H medium 8 (as water or paraffin), can guarantee high detection efficiency like this.Collimating apparatus 3 is installed between neutron detector 7 and the particle accelerator 1, to stop the first grade irradiation of 2 pairs of detectors of bremstrahlen.In order to guarantee sufficiently high neutron ejection threshold energy, collimating apparatus 3 can be done by the most handy steel.
During checking, container 4 moves in the scanning bremstrahlen field of particle accelerator 1.Under general case, neutron detector 7 is noted a certain amount of neutron ejection background.If neutron flux increases suddenly during container moves, container 4 is located corresponding exact position with the suspicious object place under the special inspection unit mark.So after having checked whole container 4, container 4 is sent back to the position of institute's mark, the material of emission photoneutron is carried out discriminating.For differentiating suspicious object 6 usefulness bremstrahlen irradiation 30-60s.If object 6 contains fissioner, then the total amount of fission fragment can run up near saturated level during irradiation, and the delayed neutron of its generation is being turned off the detected 1-2min in accelerator 1 back.If the delayed neutron flux can be ignored, then the element that suspicious object comprised has only low photoneutron reaction threshold energy, and promptly this element is not a fissioner.
In Fig. 2, neutron detector 7 is by high voltage unit 12 power supplies.The pulse that detector 7 is received is via entry time selected cell 15 after amplifier 13 and the discriminator 14.Selection of time unit 15 is by 16 controls of particle accelerator control system.The pulse that arrives when time window is opened is counted 17 records of device.
Fig. 3 illustrates the funtcional relationship of bremstrahlen pulse and time.At moment t
0The bremstrahlen pulse produces, and forms pulse 21.On behalf of the time of prompt neutron flux, curve 22 distribute.At t
1-t
2Period is in the time window, and the selection of time unit among Fig. 2 is opened, and pulse 23 can be passed through, and this pulse results from the neutron death in the detector.
Claims (12)
1. method that detects and differentiate the fissioner in the shipping goods, the checked material of bremstrahlen (2) irradiation that this method produces with straight line particle accelerator (1), use at least one neutron detector (7) and be examined the delayed neutron flux that material is launched by the detection of bremstrahlen (2) means, bremstrahlen is interrupted during measuring the delayed neutron flux, it is characterized in that
1) when neutron flux generation substantial variation, material (4) is determined with respect to the position of detector (7),
2) after having checked the whole volume of material, material (4) is sent back to according to neutron flux and changes on the determined position with respect to detector (7),
3) on this position of determining, material (4) is used bremstrahlen (2) irradiation once more, with the material of discriminating generation neutron flux,
4) in order to differentiate fissioner (6), detect the delayed neutron that fissioner is launched with at least one neutron detector (7).
2. according to the method for claim 1, the energy size that it is characterized in that bremstrahlen (2) is in the 7-10MeV scope.
3. according to the method for claim 1 or 2, it is characterized in that bremstrahlen (2) is produced by the particle accelerator (1) of a pulsing operation.
4. according to claim 1,2 or 3 method, it is characterized in that with filling
3He detector (7) detects the delayed neutron flux.
5. according to any one method among the claim 1-4, it is characterized in that for differentiating that material (4) is at least 30s with the time of bremstrahlen (2) irradiation material.
6. according to any one method among the claim 1-5, it is characterized in that control system (16) control of the operation of neutron detector record cell (17) by particle accelerator.
7. according to the method for claim 6, it is characterized in that interrupting using the time window of width in 150-200 μ s scope when bremstrahlen (2) detects the delayed neutron flux afterwards.
8. realize a kind of device of the described method of claim 1, this device is by straight line particle accelerator (1), collimating apparatus (3), being examined the equipment that bremstrahlen district that material (4) moves to the emission of straight line particle accelerator goes and detecting the equipment (7) that is examined material institute radiation emitted, it is characterized in that collimating apparatus (3) is installed between neutron detector (7) and the particle accelerator (1), and be immersed in the medium (8) to stop the first grade irradiation of bremstrahlen (2) to neutron detector (7).
9. according to the device of claim 8, it is characterized in that collimating apparatus (3) does with steel.
10. according to the device of claim 8 or 9, it is characterized in that neutron detector (7) is immersed in the medium (8) that contains H.
11., it is characterized in that medium (8) is a water according to claim 8, a kind of device of 9 or 10.
12., it is characterized in that neutron detector (7) is to fill according to any one a kind of device among the claim 8-11
3He's.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI954381A FI954381A (en) | 1995-09-18 | 1995-09-18 | Method and apparatus for detecting and identifying fissile material |
| FI954381 | 1995-09-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1196797A true CN1196797A (en) | 1998-10-21 |
Family
ID=8544038
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN96197052A Pending CN1196797A (en) | 1995-09-18 | 1996-09-11 | Method and apparatus for detecting and identifying fissionable material |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0877953A1 (en) |
| JP (1) | JPH11512528A (en) |
| CN (1) | CN1196797A (en) |
| CA (1) | CA2232039A1 (en) |
| FI (1) | FI954381A (en) |
| IL (1) | IL123633A0 (en) |
| TR (1) | TR199800440T1 (en) |
| WO (1) | WO1997011388A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009137985A1 (en) * | 2008-05-12 | 2009-11-19 | 清华大学 | Method and system for inspecting special nuclear material |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2764383B1 (en) * | 1997-06-06 | 1999-07-23 | Commissariat Energie Atomique | METHOD AND DEVICE FOR MEASURING THE RELATIVE PROPORTION OF PLUTONIUM AND URANIUM IN A BODY |
| US20090257555A1 (en) | 2002-11-06 | 2009-10-15 | American Science And Engineering, Inc. | X-Ray Inspection Trailer |
| US7099434B2 (en) * | 2002-11-06 | 2006-08-29 | American Science And Engineering, Inc. | X-ray backscatter mobile inspection van |
| US7430479B1 (en) | 2004-08-17 | 2008-09-30 | Science Applications International Corporation | System and method for analyzing content data |
| US7483511B2 (en) * | 2006-06-06 | 2009-01-27 | Ge Homeland Protection, Inc. | Inspection system and method |
| KR101687652B1 (en) * | 2014-12-04 | 2017-01-02 | 한국원자력연구원 | Slowing down time spectrometer |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4267488A (en) * | 1979-01-05 | 1981-05-12 | Trisops, Inc. | Containment of plasmas at thermonuclear temperatures |
| US4497768A (en) * | 1982-07-07 | 1985-02-05 | The United States Of America As Represented By The United States Department Of Energy | Apparatus and method for quantitatively evaluating total fissile and total fertile nuclide content in samples |
| AU6057090A (en) * | 1989-05-08 | 1990-11-29 | Scientific Innovations, Inc. | Photoneutron method of detection of explosives in luggage |
-
1995
- 1995-09-18 FI FI954381A patent/FI954381A/en unknown
-
1996
- 1996-09-11 WO PCT/FI1996/000480 patent/WO1997011388A1/en not_active Application Discontinuation
- 1996-09-11 IL IL12363396A patent/IL123633A0/en unknown
- 1996-09-11 CN CN96197052A patent/CN1196797A/en active Pending
- 1996-09-11 EP EP96930183A patent/EP0877953A1/en not_active Withdrawn
- 1996-09-11 JP JP9512412A patent/JPH11512528A/en active Pending
- 1996-09-11 TR TR1998/00440T patent/TR199800440T1/en unknown
- 1996-09-11 CA CA002232039A patent/CA2232039A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009137985A1 (en) * | 2008-05-12 | 2009-11-19 | 清华大学 | Method and system for inspecting special nuclear material |
| US9081099B2 (en) | 2008-05-12 | 2015-07-14 | Nuctech Company Limited | Method and system for detecting special nuclear materials |
| US9268027B2 (en) | 2008-05-12 | 2016-02-23 | Nuctech Company Ltd. | Method and system for detecting special nuclear materials |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2232039A1 (en) | 1997-03-27 |
| WO1997011388A1 (en) | 1997-03-27 |
| TR199800440T1 (en) | 1998-06-22 |
| FI954381A (en) | 1997-03-19 |
| EP0877953A1 (en) | 1998-11-18 |
| JPH11512528A (en) | 1999-10-26 |
| FI954381A0 (en) | 1995-09-18 |
| IL123633A0 (en) | 1998-10-30 |
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| C01 | Deemed withdrawal of patent application (patent law 1993) | ||
| WD01 | Invention patent application deemed withdrawn after publication |