JPH02157696A - Non-destructive analysis apparatus for fissile material - Google Patents
Non-destructive analysis apparatus for fissile materialInfo
- Publication number
- JPH02157696A JPH02157696A JP63310194A JP31019488A JPH02157696A JP H02157696 A JPH02157696 A JP H02157696A JP 63310194 A JP63310194 A JP 63310194A JP 31019488 A JP31019488 A JP 31019488A JP H02157696 A JPH02157696 A JP H02157696A
- Authority
- JP
- Japan
- Prior art keywords
- neutron
- neutron source
- neutrons
- measurement
- source
- 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 description 24
- 230000002285 radioactive effect Effects 0.000 claims abstract description 10
- 238000005259 measurement Methods 0.000 claims description 63
- 230000001066 destructive effect Effects 0.000 claims description 11
- 239000004698 Polyethylene Substances 0.000 abstract description 17
- -1 polyethylene Polymers 0.000 abstract description 17
- 229920000573 polyethylene Polymers 0.000 abstract description 17
- 238000006243 chemical reaction Methods 0.000 description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 230000004992 fission Effects 0.000 description 6
- 229910002804 graphite Inorganic materials 0.000 description 6
- 239000010439 graphite Substances 0.000 description 6
- 230000004907 flux Effects 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- 230000003111 delayed effect Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- OYEHPCDNVJXUIW-FTXFMUIASA-N 239Pu Chemical compound [239Pu] OYEHPCDNVJXUIW-FTXFMUIASA-N 0.000 description 1
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- 229910052778 Plutonium Inorganic materials 0.000 description 1
- YZCKVEUIGOORGS-NJFSPNSNSA-N Tritium Chemical compound [3H] YZCKVEUIGOORGS-NJFSPNSNSA-N 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 239000011358 absorbing material Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- HGLDOAKPQXAFKI-OUBTZVSYSA-N californium-252 Chemical compound [252Cf] HGLDOAKPQXAFKI-OUBTZVSYSA-N 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910052805 deuterium Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000003758 nuclear fuel Substances 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052722 tritium Inorganic materials 0.000 description 1
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 1
- JFALSRSLKYAFGM-OIOBTWANSA-N uranium-235 Chemical compound [235U] JFALSRSLKYAFGM-OIOBTWANSA-N 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
Description
【発明の詳細な説明】
〔発明の目的〕
（産業上の利用分野）
本発明は核燃料サイクル施設で取り扱われる核分裂性物
質の非破壊分析装置に係り、特に超ウラン元素が含まれ
る廃棄物の測定に好適な核分裂性物質の非破壊分析Ｖｉ
誼に関する。[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention relates to a non-destructive analysis device for fissile materials handled in nuclear fuel cycle facilities, and is particularly applicable to the measurement of waste containing transuranic elements. Non-destructive analysis of fissile material suitable for
Concerning insults.
（従来の技術）
燃料製造工場等で発生する廃棄物やスクラップに含まれ
るウランやプルトニウムを定母することは、臨界管理や
儒棄物の放射能管理あるいは計聞管理の観点から必要で
あり、多種類の非破壊測定法が開発され実用化されてい
る。(Prior art) It is necessary to standardize uranium and plutonium contained in waste and scrap generated at fuel manufacturing plants, etc. from the viewpoint of criticality control, radioactivity control of waste materials, and accounting control. Many types of non-destructive measurement methods have been developed and put into practical use.
これらの測定法の中で代表的な中性子消滅時間差法（Ｄ
ＤＴ法）を用いた従来の核分裂性物質の非破壊分析装置
の一例を第４図に示す。第４図において、中性子減速体
としてのポリエチレン１およびグラフフイ）−２により
測定室Ａが形成され、この測定室Ａ内に被測定試料３と
、その被測定試料３に中性子を照射するＤＴ中性子発生
管４と、熱中性子束モニタ検出器５とが収容される。Ｄ
Ｔ中性子発生管４は図示しないＯＴ中性子発生装置の発
生部であり、中性子源としてのＤＴ中性子発生装置は重
水素と三重水素の核反応で中性子を発生させるものであ
る。Among these measurement methods, the neutron annihilation time difference method (D
An example of a conventional non-destructive analysis device for fissile material using the DT method is shown in FIG. In FIG. 4, a measurement chamber A is formed by polyethylene 1 as a neutron moderator and Graphite-2, and within this measurement chamber A is a sample to be measured 3 and a DT neutron generator that irradiates the sample to be measured 3 with neutrons. A tube 4 and a thermal neutron flux monitor detector 5 are housed therein. D
The T neutron generator tube 4 is a generating part of an OT neutron generator (not shown), and the DT neutron generator as a neutron source generates neutrons through a nuclear reaction between deuterium and tritium.
測定室Ａを構成する中性子減速体としてのポリエチレン
１およびグラファイト２の壁内には、高速中性子検出器
６が配設される。高速中性子検出器６は、カドミウム等
からなる熱中性子吸収板７で取り囲まれたポリエチレン
８の中に熱中性子検出器９が収容されて構成される。A fast neutron detector 6 is disposed within the walls of polyethylene 1 and graphite 2 as neutron moderators that constitute the measurement chamber A. The fast neutron detector 6 is constructed by housing a thermal neutron detector 9 in polyethylene 8 surrounded by a thermal neutron absorbing plate 7 made of cadmium or the like.
この核分裂性物質の非破壊分析装置において、ＤＴ中性
子発生管４を短時間（数１０μ秒以下）作動させてパル
ス状に中性子を発生させる。ＤＴ反応で発生した中性子
は約１４ＭｅＶのエネルギを有する高速中性子であり、
この高速中性子は測定室Ａ内を進み、グラファイト２に
より減速され、さらにポリエチレン１により減速されか
つ反射される。このようにして半減期約１０μ秒で高速
中性子は測定室Ａ内から消滅する。In this nondestructive analysis device for fissile materials, the DT neutron generator tube 4 is operated for a short time (several tens of microseconds or less) to generate neutrons in a pulsed manner. The neutrons generated in the DT reaction are fast neutrons with an energy of about 14 MeV,
These fast neutrons travel within the measurement chamber A, are decelerated by the graphite 2, and are further decelerated and reflected by the polyethylene 1. In this way, the fast neutrons disappear from the measurement chamber A with a half-life of about 10 μsec.
こうして、ＤＴ反応により発生した高速中性子は、グラ
ファイト２およびポリエチレン１による減速により、発
生後１００μ秒程度の時間内に熱中性子となる。ポリエ
チレン１の反射により測定ｖＡ内に戻った熱中性子は、
半減期（０，５〜１ｍ秒）で測定室Ａ内に滞在する。測
定室Ａ内に滞在する熱中性子の一部は、被測定試料３中
にプルトニウム２３９、ウラン２３５等の核分裂性物質
があれば、これに吸収されて核分裂反応を誘起し、核分
裂反応に伴って高速中性子を発生させる。In this way, the fast neutrons generated by the DT reaction become thermal neutrons within about 100 microseconds after generation due to deceleration by the graphite 2 and polyethylene 1. Thermal neutrons returned to the measured vA by reflection from polyethylene 1 are
It stays in the measurement chamber A for a half-life (0.5-1 msec). If there is a fissile material such as plutonium-239 or uranium-235 in the measurement sample 3, a part of the thermal neutrons staying in the measurement chamber A will be absorbed by the fissile material and induce a nuclear fission reaction. Generate fast neutrons.
したがって、ＤＴ中性子発生管４でパルス状に照射中性
子を発生させてから１００μ秒程戊軽過して後、高速中
性子を検出して計数すれば、この計数は照射中性子を含
まず、被測定試料３中で誘起された核分裂反応数に比例
するので、被測定試料３中の核分裂性物質を定理測定す
ることができる。その高速中性子を検出するため高速中
性子検出器６が配設されており、熱中性子吸収板７によ
り高速中性子のみがポリエチレン８内に透過し、ポリエ
チレン８により減速されて熱中性子となった後、熱中性
子検出器９に検出される。Therefore, if the DT neutron generator tube 4 generates irradiated neutrons in a pulsed manner and then detects and counts the fast neutrons after they have passed for about 100 μs, this count does not include the irradiated neutrons and the sample to be measured is Since the number of fission reactions induced in the sample 3 is proportional to the number of fission reactions, the fissile material in the sample 3 to be measured can be measured by theorem. A fast neutron detector 6 is installed to detect the fast neutrons, and only the fast neutrons are transmitted into the polyethylene 8 by the thermal neutron absorption plate 7, and after being decelerated by the polyethylene 8 and turned into thermal neutrons, It is detected by the neutron detector 9.
（発明が解決しようとする課題）
従来の非破壊分析ｉ置に備えられたＤＴ中性子発生管４
は１回当たりの中性子の発生量に限度があるとともに、
中性子の全発生量にも限度がある。このため、中性子の
発生強度に限界があり測定精度に影響するとともに、使
用頻度が多い場合には寿命が短く、ＤＴ中性子発生管４
を頻繁に取り替える必要が生じ保守管理上課題がある。(Problem to be solved by the invention) DT neutron generating tube 4 provided in a conventional non-destructive analysis equipment
There is a limit to the amount of neutrons generated per time, and
There is also a limit to the total amount of neutrons generated. For this reason, there is a limit to the intensity of neutron generation, which affects measurement accuracy, and if it is used frequently, the lifespan is short, and the DT neutron generator tube 4
It is necessary to replace the parts frequently, which poses maintenance management issues.
また、ＤＴ中性子発生装置は中性子を発生させるために
Ｎ源を必要とし、この電源の電圧の変動により中性子の
発生強度にばらつきが生じ、装置の校正、調整が必要と
なる。Further, the DT neutron generator requires an N source to generate neutrons, and fluctuations in the voltage of this power source cause variations in the intensity of neutron generation, making it necessary to calibrate and adjust the device.
本発明は上記の事情を考慮してなされたもので、使用頻
度上の制限がなく、保守性に優れ、かつ安定した中性子
発生強度を確保することができ、測定精度を向上させる
ことができる核分裂性物質の非破壊分析装置を提供する
ことを目的とする。The present invention has been made in consideration of the above circumstances, and is a nuclear fission device that has no restrictions on frequency of use, has excellent maintainability, can ensure stable neutron generation intensity, and can improve measurement accuracy. The purpose of this research is to provide a non-destructive analysis device for chemical substances.
（課題を解決するための手段）
本発明は、中性子減速体で取り囲まれて形成された測定
室内に被測定試料を収容し、上記中性子減速体の壁に被
測定試料からの高速中性子を検出する高速中性子検出器
を設けた核分裂性物質の非破壊分析装置において、放射
性同位元素からなる中性子源と、その中性子源を上記測
定室内に時間間隔をおいて滞在させる中性子源回転移動
装置とを備えたものである。(Means for Solving the Problems) The present invention accommodates a sample to be measured in a measurement chamber surrounded by a neutron moderator, and detects fast neutrons from the sample to be measured on the wall of the neutron moderator. A non-destructive analysis device for fissile materials equipped with a high-speed neutron detector, comprising a neutron source made of a radioactive isotope and a neutron source rotating device that causes the neutron source to stay in the measurement chamber at time intervals. It is something.
（作用）
放射性同位元素からなる中性子源と、測定室内に中性子
源を時間間隔をおいて滞在さける中性子源回転移動装置
とを備えたから、従来のような中性子発生装置を備える
ことなく、測定室内に一定時間間隔をおいて中性子を照
射することができる。また、中性子源として放射性同位
元素を用いるため、使用頻度上の制限がなく寿命が長い
。したがって、中性子源を頻繁に取り替える必要がなく
、保守性に優れている。さらに、電源を必要とすること
なく中性子を発生することができるため、中性子発生強
度のばらつきがなく、安定した中性子発生強度を確保す
ることができる。しかも、１回当たりの中性子の発生量
に限界がない。したがって、核分裂性物質の測定精度を
向上させることができる。(Function) Since it is equipped with a neutron source made of radioactive isotopes and a neutron source rotation and movement device that prevents the neutron source from staying in the measurement chamber at time intervals, it is possible to move the neutron source into the measurement chamber without having to install a neutron generator like in the past. Neutrons can be irradiated at regular time intervals. Furthermore, since radioactive isotopes are used as the neutron source, there are no restrictions on the frequency of use, and the lifespan is long. Therefore, there is no need to frequently replace the neutron source, and maintainability is excellent. Furthermore, since neutrons can be generated without requiring a power source, there is no variation in neutron generation intensity, and stable neutron generation intensity can be ensured. Furthermore, there is no limit to the amount of neutrons generated per cycle. Therefore, the accuracy of measuring fissile material can be improved.
〈実施例）
本発明の一実施例について添付図面を参照して説明する
。<Example> An example of the present invention will be described with reference to the accompanying drawings.
第１図および第２図は本発明に係る核分裂性物質の非破
壊分析装置の一実施例を示す断面図である。第１図およ
び第２図において第５図と同一の部分については同一の
符号を付して詳細な説明を省略する。FIGS. 1 and 2 are cross-sectional views showing an embodiment of a non-destructive analysis device for fissile material according to the present invention. In FIGS. 1 and 2, the same parts as in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.
非破壊分析装置には放射性同位元素からなる中性子源１
０と、その中性子源１０を測定室Ａ内に時間間隔をおい
て滞在させる中性子源回転移動装置１１とが備えられる
。中性子源１０としては例えばカリホルニウム２５２
（Ｏｆ＞が用いられる。中性子発生強度は６Ｘｂ
ものが好ましい。The non-destructive analysis device has a neutron source 1 consisting of radioactive isotopes.
0 and a neutron source rotation and movement device 11 that causes the neutron source 10 to stay in the measurement chamber A at time intervals. As the neutron source 10, for example, californium 252
(Of> is used. The neutron generation intensity is preferably 6Xb.
中性子源回転移動装置１１は回転円板１２を有し、この
回転円板１２の外周縁に中性子源１０が設けられる。回
転円板１２の外周縁には、中性子源１０が設けられた位
置と例えば９０度、１８０度、２７０度移相が異なる位
置にパランサ１３が設けられる。回転円板１２は、モー
タ等の回転駆動源１４により高速回転されるようになっ
ている。The neutron source rotation and movement device 11 has a rotating disk 12 , and the neutron source 10 is provided on the outer peripheral edge of the rotating disk 12 . A parancer 13 is provided on the outer peripheral edge of the rotating disk 12 at a position different in phase shift from the position where the neutron source 10 is provided, for example, by 90 degrees, 180 degrees, or 270 degrees. The rotating disk 12 is configured to be rotated at high speed by a rotational drive source 14 such as a motor.
回転円板１２は、中性子減速体としてのポリエチレン１
およびグラフ７イト２の側壁に形成された隙間１５を通
って、その外周縁の一部が測定室Ａ内に挿入される。こ
の隙間１５は第２図において広く描かれているが、測定
精度への影響を防ぐため、実際には可能な限り狭く形成
される。The rotating disk 12 is made of polyethylene 1 as a neutron moderator.
A part of the outer peripheral edge of the graphite 2 is inserted into the measurement chamber A through a gap 15 formed in the side wall of the graphite 2. Although this gap 15 is drawn wide in FIG. 2, it is actually formed as narrow as possible to prevent it from affecting measurement accuracy.
また、回転円板１２の他方の半分は中性子源格納容器１
６に形成された溝１７内に挿入される。In addition, the other half of the rotating disk 12 is connected to the neutron source containment vessel 1.
It is inserted into the groove 17 formed in 6.
中性子源格納容器１６は例えばポリエチレンのブロック
からなり、回転円板１２の半分を挿入しうるように半円
形状の溝１７が形成される。また、中性子源格納容器１
６と測定室へを形成するポリエチレン１の壁との間から
中性子が漏れるため、その周囲を取り囲んで中性子遮蔽
材１８が設けられる。中性子遮蔽材１８は例えばポリエ
チレンにより簡易に形成される。The neutron source containment vessel 16 is made of a polyethylene block, for example, and has a semicircular groove 17 into which half of the rotating disk 12 can be inserted. In addition, neutron source containment vessel 1
Since neutrons leak between the polyethylene wall 1 and the polyethylene wall 1 forming the measurement chamber, a neutron shielding material 18 is provided surrounding the neutron shielding material 18. The neutron shielding material 18 is simply made of polyethylene, for example.
中性子源格納容器１６は、第１図における左側に延長し
、回転円板１２のほとんどを取り囲むように形成しても
よい。この場合には中性子遮蔽材１８が不要となる。The neutron source containment vessel 16 may be formed to extend to the left in FIG. 1 and surround most of the rotating disk 12. In this case, the neutron shielding material 18 becomes unnecessary.
回転円板１２には中性子源１０に隣接して位置検出器１
９が設けられる。回転円板１２の周囲には、この位置検
出器１９に対応する位置検出器２０と、位置検出器２１
とが設けられる。回転円板１２が矢印Ｂの方向へ回転す
る場合には、位置検出器２０は測定室Ａの入口に配設さ
れ、他方の位置検出器２１は中性子源格納容器１６の入
口に配設され、これにより中性子源１０が測定室Ａ内に
滞在している時間や中性子源格納容器１６内に滞在して
いる時間を検出することができる。A position detector 1 is mounted on the rotating disk 12 adjacent to the neutron source 10.
9 is provided. Around the rotating disk 12, a position detector 20 corresponding to this position detector 19 and a position detector 21 are arranged.
and is provided. When the rotating disk 12 rotates in the direction of arrow B, the position detector 20 is arranged at the entrance of the measurement chamber A, the other position detector 21 is arranged at the entrance of the neutron source containment vessel 16, This makes it possible to detect the time the neutron source 10 stays in the measurement chamber A and the time the neutron source 10 stays in the neutron source containment vessel 16.
なお、符号２２は測定試料３を回転させるターンテーブ
ルを示す。Note that the reference numeral 22 indicates a turntable for rotating the measurement sample 3.
ここで、回転円板１２の半径を１ｍとし回転数１００回
／秒で回転するものとする。この時、３６０度を回転す
る中で４５疾の範囲が中性子源１０が測定室Ａ内を移動
する範囲とし、６７．５度移動した後、１８０度の範囲
で中性子源格納容器１６内を移動するものとする。Here, it is assumed that the radius of the rotating disk 12 is 1 m and that it rotates at a rotation speed of 100 times/second. At this time, while rotating 360 degrees, the range of 45 degrees is the range in which the neutron source 10 moves within the measurement chamber A, and after moving 67.5 degrees, it moves within the neutron source containment vessel 16 within a range of 180 degrees. It shall be.
そうすると、回転数１００回／秒から時間を求めると、
１回転の時間が１０ｍ秒、中性子源１０が測定室Ａを移
動する時間（照射時間）は１．２５ｍ秒、中性子源格納
容器１６への移動時間が１゜８７５ｍ秒、中性子源格納
容器１６内の移動時間が５ｍ秒、測定室Ａへの移動時間
が１．８７５ｍ秒となる。したがって、中性子源１０の
強度を６ｘｂ
射は７．５Ｘ１０６ｎ／照射、持ち時間１．９ｍ秒、測
定時間５ｍ秒で１０ｍ秒の繰り返し測定を行うこととな
る。Then, if you calculate the time from the rotation speed of 100 times/second,
The time for one rotation is 10 msec, the time for the neutron source 10 to move through the measurement chamber A (irradiation time) is 1.25 msec, and the time for movement to the neutron source containment vessel 16 is 1°875 msec, inside the neutron source containment vessel 16. The travel time to the measurement chamber A is 5 msec, and the travel time to the measurement room A is 1.875 msec. Therefore, the intensity of the neutron source 10 is 6×b, the irradiation is 7.5×10 6 n/irradiation, the duration is 1.9 ms, the measurement time is 5 ms, and the measurement is repeated for 10 ms.
ところで、ＤＴ中性子発生装置を利用した従来の非破壊
分析装置は、例えば２００ｐドラム缶中の１１ｙＪの核
分裂性物質を検出するという非常に高感度の分析装置で
ある。この装置の中性子発生強度はｌＸ１０６ｎ／照射
で、照射後０゜５〜約５■秒の範囲の高速中性子強度を
測定し、これにより核分裂性物質を定量する。By the way, a conventional nondestructive analysis device using a DT neutron generator is an extremely sensitive analysis device that can detect, for example, 11yJ of fissile material in a 200p drum. The neutron generation intensity of this device is 1×10 6 n/irradiation, and the fast neutron intensity is measured in the range of 0°5 to about 5 seconds after irradiation, thereby quantifying the amount of fissile material.
この場合、測定室Ａ内に残留する中性子の消滅する半減
期は約１ｍ秒であるので、中性子源を放射性同位元素か
らなる照射線源１０とした場合は、Ｄ Ｔ中性子発生管
４の場合と比較すると、中性子照射後的２ｍ秒遅れて即
発中性子を計数することとなる。このため、その間に熱
中性子束が消滅し、ＤＴ中性子発生管４の場合に比較し
て、１／４の強度の熱中性子束で測定を行うこととなる
。しかし、照射中性子強度が７．５倍あるので、全体的
に考えると、放射性同位元素からなる照射線源１０によ
る測定は、ＤＴ中性子発生管４の場合の２倍弱の即発中
性子数を計数することができる。したがって、従来装置
の約２倍のシグナル量が得られ、測定精度が向上する。In this case, the half-life of the neutrons remaining in the measurement chamber A is approximately 1 ms, so when the neutron source is the irradiation source 10 made of a radioactive isotope, it is different from the case of the D T neutron generator tube 4. By comparison, prompt neutrons are counted with a delay of 2 msec after neutron irradiation. Therefore, the thermal neutron flux disappears during that time, and the measurement is performed with a thermal neutron flux that is 1/4 of the intensity compared to the case of the DT neutron generating tube 4. However, since the intensity of irradiated neutrons is 7.5 times higher, overall, measurements using the irradiation source 10 made of radioactive isotopes count nearly twice as many prompt neutrons as in the case of the DT neutron generator 4. be able to. Therefore, approximately twice the amount of signal can be obtained as compared to the conventional device, and measurement accuracy is improved.
非破壊分析装置には第３図に示すように、２系統の計数
系が備えられる。これは２系統に限らず１系統、３系統
、４系統であってもよい。各系統には例えば４本の熱中
性子検出器９が備えられる。As shown in FIG. 3, the non-destructive analysis device is equipped with two counting systems. This is not limited to two systems, but may be one, three, or four systems. Each system is equipped with, for example, four thermal neutron detectors 9.
この熱中性子検出器９は前述のように熱中性子吸収材７
で取り囲まれた中性子減速材８の中に収容される。１系
統に備えられる熱中性子検出器９は１本でも２本でもよ
く、また５本以上設けてもよい。中性子検出器９には動
作用の高圧電源２５がプリアンプ２６を介して接続され
る。This thermal neutron detector 9 has a thermal neutron absorbing material 7 as described above.
It is housed in a neutron moderator 8 surrounded by. One or two thermal neutron detectors 9 may be provided in one system, or five or more thermal neutron detectors 9 may be provided. A high voltage power supply 25 for operation is connected to the neutron detector 9 via a preamplifier 26 .
中性子検出器９により熱中性子が検出されると、プリア
ンプ２６に微小な信号が入力され、前段増幅器としての
プリアンプ２６により微小信号が増幅される。増幅され
た信号はメインアンプ２７に入力され、この主増幅器と
してのメインアンプ２７により増幅されて、単波高分析
器２８に入力される。単波高分析器２８はメインアンプ
２７から入力したランプ出力が一定の電圧を有する場合
に中性子１個として検知する。When thermal neutrons are detected by the neutron detector 9, a minute signal is input to the preamplifier 26, and the minute signal is amplified by the preamplifier 26 as a preamplifier. The amplified signal is input to the main amplifier 27, amplified by the main amplifier 27 as a main amplifier, and input to the single wave height analyzer 28. The single wave height analyzer 28 detects a single neutron when the lamp output inputted from the main amplifier 27 has a constant voltage.
単波高分析器２８が中性子を検知１′ると、カウンタ２
９に信号が入力され、カウンタ２９に保持されている数
値が１個づつ減少あるいは増加する。When the single wave height analyzer 28 detects a neutron 1', the counter 2
A signal is input to counter 29, and the numerical value held in counter 29 is decreased or increased by one.
カウンタ２９にはパルス発生器３０が接続されでおり、
このパルス発生器３０は位置検出器２０゜２１からの信
号を受けて、所定の時間カウンタ２９が作動するような
論理信号をゲート信号３１としてカウンタ２９に出力す
る。カウンタ２９は電気レベルの整合やタイミングの調
整を行う仲介料りυ装置としてのインターフェイス３２
を介して計算機３３に接続される。A pulse generator 30 is connected to the counter 29,
This pulse generator 30 receives the signal from the position detector 20.degree. 21 and outputs a logic signal to the counter 29 as a gate signal 31, which causes the counter 29 to operate for a predetermined period of time. The counter 29 is an interface 32 that serves as an intermediary device that matches electrical levels and adjusts timing.
It is connected to the computer 33 via.
計ｎ＊３３にはインターフェイス３４を介して位置検出
器２０．２１が接続され、インターフェイス３５を介し
て回転駆動源１４等の駆動系３６が接続される。計算機
３３は駆動系３６に信号を送り回転駆動源１４の回転、
停止および回転数等を制御するとともに、位置検出）８
２０．２１からの信号を受けて実際の回転数をフィード
バックする。また、計！！１１３３はインターフェイス
３２を介してカウンタ２９から信号を入力し、中性子計
数を積算し、これを演算処理して核分裂性物質団を求め
る。A position detector 20.21 is connected to the total n*33 via an interface 34, and a drive system 36 such as the rotational drive source 14 is connected via an interface 35. The computer 33 sends a signal to the drive system 36 to rotate the rotational drive source 14.
Controls stop and rotation speed, as well as position detection) 8
20.Receives the signal from 21 and feeds back the actual rotation speed. Also, total! ! 1133 inputs the signal from the counter 29 via the interface 32, integrates the neutron counts, and performs arithmetic processing to obtain the fissile material group.
なお、カウンタ２９は計算機３３により制御してもよい
が、パルス発生器３０により直接制御する方が反応が速
いため、本実施例ではパルス発生器３０を介してカウン
タ２９を制御した。The counter 29 may be controlled by the computer 33, but since the response is faster when directly controlled by the pulse generator 30, the counter 29 was controlled via the pulse generator 30 in this embodiment.
次に上記実施例の作用について第４図に従って説明する
。Next, the operation of the above embodiment will be explained with reference to FIG. 4.
まず、中性子源１０を設置した回転円板１２を１００回
／秒程度の所定の速度で連続的に回転するように準備す
る。次に、測定試料３を遠隔操作で測定室Ａ内のターン
テーブル２２上に設置し、計算機３３に図示しない入力
装置から測定条件を入力し、さらに測定開始命令を入力
する。First, the rotating disk 12 on which the neutron source 10 is installed is prepared to rotate continuously at a predetermined speed of about 100 times/second. Next, the measurement sample 3 is placed on the turntable 22 in the measurement chamber A by remote control, measurement conditions are input to the computer 33 from an input device (not shown), and a measurement start command is input.
中性子源１０は連続的に回転しており、中性子源１０に
隣接して設けられた位置検出器１９が位置検出器２０．
２１に対向する位置を通過すると、測定室Ａ内に入る中
性子源１０の位置や中性子源格納容器１６内に入る中性
子源１０の位置を検出することができる。The neutron source 10 is continuously rotating, and a position detector 19 provided adjacent to the neutron source 10 is connected to a position detector 20 .
21, the position of the neutron source 10 entering the measurement chamber A and the position of the neutron source 10 entering the neutron source containment vessel 16 can be detected.
中性子源１０が測定室Ａ内に入ると、中性子源１０Ｇ、
を高連中性子を放出しながら測定室Ａ内を移動する。中
性子源１０から放出された高速中性子はグラフ７イト２
およびポリエチレン１により瞬間的に減速されて熱中性
子となり、相対的に長時間測定室Ａ内に滞在する。そし
て、中性子源１０が測定空Ａ外へ移動し、高速中性子が
測定室Ａから出ていくと、測定室Ａ内の中性子は熱中性
子のみとなり、この熱中性子が測定試料３中に含まれる
核分裂性物質を照射し、その核分裂性物質が核分裂反応
を起こして即発中性子を発生する。When the neutron source 10 enters the measurement chamber A, the neutron source 10G,
moves within measurement chamber A while emitting a high number of neutrons. The fast neutrons emitted from the neutron source 10 are graph 7ite 2
The neutrons are momentarily decelerated by the polyethylene 1 and become thermal neutrons, which stay in the measurement chamber A for a relatively long time. Then, when the neutron source 10 moves out of the measurement space A and the fast neutrons leave the measurement chamber A, the neutrons in the measurement chamber A become only thermal neutrons, and these thermal neutrons cause nuclear fission contained in the measurement sample 3. The fissile material undergoes a fission reaction and generates prompt neutrons.
この場合、中性子源１０が測定室Ａを出て中性子源格納
容器１６内に入った状態で中性子計数の開始位置を検出
し、高速中性子検出器６で即発中性子を所定の時間測定
する。１回の照射と即発中性子の計数では統計上十分な
計数が得られないため、上記のような照射と測定のサイ
クルを所定の回数繰り返す。次に、所定の回数に達した
ら、測定試料３をターンテーブル２２により所定の角度
（例えば９０度）回転し、１回転して初期位置に戻るま
で上記測定サイクルを繰り返す。ターンテーブル２２は
ゆっくりした速度で連続的に回転させるようにしてもよ
い。測定が終わると、中性子計数を積算し、これを演桿
処理して核分裂性物質ωを求め、これを図示しない出力
装置に出力する。In this case, the neutron counting start position is detected with the neutron source 10 leaving the measurement chamber A and entering the neutron source containment vessel 16, and the fast neutron detector 6 measures prompt neutrons for a predetermined period of time. Since a statistically sufficient count cannot be obtained with one irradiation and counting of prompt neutrons, the above-described cycle of irradiation and measurement is repeated a predetermined number of times. Next, when a predetermined number of times is reached, the measurement sample 3 is rotated by a predetermined angle (for example, 90 degrees) by the turntable 22, and the above measurement cycle is repeated until it rotates once and returns to the initial position. The turntable 22 may be rotated continuously at a slow speed. When the measurement is completed, the neutron counts are integrated, and the results are subjected to computational processing to obtain the fissile material ω, which is output to an output device (not shown).
そして、測定試料３を遠隔で搬出し、次の測定試料３を
ターンテーブル２２に装荷する。Then, the measurement sample 3 is carried out remotely, and the next measurement sample 3 is loaded onto the turntable 22.
このように上記実施例によれば、放射性同位元素からな
る中性子源１０を用い、この中性子源１０を中性子源回
転移動装＠１１により一定の時間間隔をおいて測定室Ａ
内に滞在させるようにしたから、従来のＤＴ中性子発生
管４のような使用頻度上の制限がなく、取り替え頻度が
少ないことから保守性に優れている。また、従来のＤＴ
中性子発生装置のような電源を必要としないため、安定
した中性子発生強度を確保することができるとともに、
使用頻度上の制限がないので１回測定当たりの中性子発
生ｍを上げることができ、測定ｇ度を向上させることが
できる。In this way, according to the above embodiment, the neutron source 10 made of a radioactive isotope is used, and the neutron source 10 is moved to the measurement room A at regular intervals by the neutron source rotation moving device @11.
Since the neutron generating tube 4 is made to stay inside the tube, there is no restriction on the frequency of use unlike the conventional DT neutron generating tube 4, and maintenance is excellent because the frequency of replacement is low. In addition, conventional DT
Since it does not require a power source like a neutron generator, it is possible to ensure stable neutron generation intensity, and
Since there is no limit on the frequency of use, it is possible to increase the number of neutrons generated per measurement (m), and the measurement g degree can be improved.
なお、上記実施例においては回転円板１２を連続的に高
速回転させるようにしたが、本発明はこれに限定されず
、回転円板１２をステップ状に回転運動させ、中性子ｒ
Ａ１０をステップ的に測定室Ａ内に滞在させ、測定試料
３から発生される遅発中性子を熱中突子束モニタ検出器
５により検出し、その遅発中性子の検出結果と前記実施
例の即発中性子の検出結果の両方を演算処理することに
より核分裂性物質を分析するようにしてもよい。ここで
中性子源１０をステップ的に測定室Ａ内に滞在させると
は、例えば測定室Ａ内に５秒Ｉ′ｉ′Ｊ滞在させ、その
後中性子源格納容器１６内へ移動し、この中性子源格納
容器１６内で５秒間滞在させるようなことをいう。In the above embodiment, the rotating disk 12 is continuously rotated at high speed, but the present invention is not limited to this, and the rotating disk 12 is rotated in a stepwise manner to generate
A10 is made to stay in the measurement chamber A in a stepwise manner, delayed neutrons generated from the measurement sample 3 are detected by the hot proton flux monitor detector 5, and the detection results of the delayed neutrons and the prompt neutrons of the above embodiment are compared. The fissile material may be analyzed by processing both of the detection results. Here, to make the neutron source 10 stay in the measurement chamber A in steps means, for example, to make it stay in the measurement chamber A for 5 seconds I'i'J, and then move it into the neutron source containment vessel 16 and move it to the neutron source storage container 16. This means staying in the container 16 for 5 seconds.
本発明に係る核分裂性物質の非破壊分析装置は、放射性
同位元素からなる中性子源と、その中性子源を測定室内
に時間間隔をおいて滞在させる中性子源回転移動装置と
を備えたから、従来の中性子発生管のような使用頻度上
の制限がなく、保守性に優れ、かつ安定した中性子発生
強度を確保することができるとともに、測定精度を向上
させることができる。The non-destructive analysis device for fissile materials according to the present invention is equipped with a neutron source made of a radioactive isotope and a neutron source rotating device that allows the neutron source to stay in a measurement chamber at time intervals. Unlike generator tubes, there are no restrictions on the frequency of use, and the neutron generator has excellent maintainability and can ensure stable neutron generation intensity, as well as improve measurement accuracy.
１・・・ポリエチレン、２・・・グラファイト、３・・
・測定試料、５・・・熱中性子モニタ検出器、６・・・
高速中性子検出器、１０・・・中性子源、１１・・・中
性子源回転移動装置、１２・・・回転円板、１４・・・
回転駆動源、１６・・・中性子源格納容器。1... Polyethylene, 2... Graphite, 3...
・Measurement sample, 5... Thermal neutron monitor detector, 6...
High-speed neutron detector, 10... Neutron source, 11... Neutron source rotation moving device, 12... Rotating disk, 14...
Rotary drive source, 16...neutron source containment vessel.
Claims (1)
測定試料を収容し、上記中性子減速体の壁に被測定試料
からの高速中性子を検出する高速中性子検出器を設けた
核分裂性物質の非破壊分析装置において、放射性同位元
素からなる中性子源と、その中性子源を上記測定室内に
時間間隔をおいて滞在させる中性子源回転移動装置とを
備えたことを特徴とする核分裂性物質の非破壊分析装置
。Non-destruction of fissile materials in which a sample to be measured is housed in a measurement chamber surrounded by a neutron moderator, and a fast neutron detector is installed on the wall of the neutron moderator to detect fast neutrons from the sample to be measured. A non-destructive analysis device for fissile materials, characterized in that the analysis device is equipped with a neutron source made of a radioactive isotope and a neutron source rotating device that allows the neutron source to stay in the measurement chamber at time intervals. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63310194A JPH02157696A (en) | 1988-12-09 | 1988-12-09 | Non-destructive analysis apparatus for fissile material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63310194A JPH02157696A (en) | 1988-12-09 | 1988-12-09 | Non-destructive analysis apparatus for fissile material |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02157696A true JPH02157696A (en) | 1990-06-18 |
Family
ID=18002303
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63310194A Pending JPH02157696A (en) | 1988-12-09 | 1988-12-09 | Non-destructive analysis apparatus for fissile material |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02157696A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998059347A1 (en) * | 1997-06-19 | 1998-12-30 | European Organization For Nuclear Research | Neutron-driven element transmuter |
| JP2007121156A (en) * | 2005-10-28 | 2007-05-17 | Toshiba Corp | Subcriticality monitor and method |
| JP2020051895A (en) * | 2018-09-27 | 2020-04-02 | 国立研究開発法人日本原子力研究開発機構 | Nuclear material detector |
-
1988
- 1988-12-09 JP JP63310194A patent/JPH02157696A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998059347A1 (en) * | 1997-06-19 | 1998-12-30 | European Organization For Nuclear Research | Neutron-driven element transmuter |
| JP2007121156A (en) * | 2005-10-28 | 2007-05-17 | Toshiba Corp | Subcriticality monitor and method |
| JP2020051895A (en) * | 2018-09-27 | 2020-04-02 | 国立研究開発法人日本原子力研究開発機構 | Nuclear material detector |
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