JPS646709B2 - - Google Patents
Info
- Publication number
- JPS646709B2 JPS646709B2 JP6264281A JP6264281A JPS646709B2 JP S646709 B2 JPS646709 B2 JP S646709B2 JP 6264281 A JP6264281 A JP 6264281A JP 6264281 A JP6264281 A JP 6264281A JP S646709 B2 JPS646709 B2 JP S646709B2
- Authority
- JP
- Japan
- Prior art keywords
- neutron
- anode
- cathode
- uranium
- electrode
- 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.)
- Expired
Links
- 239000012212 insulator Substances 0.000 claims description 9
- JFALSRSLKYAFGM-OIOBTWANSA-N uranium-235 Chemical compound [235U] JFALSRSLKYAFGM-OIOBTWANSA-N 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- WABPQHHGFIMREM-UHFFFAOYSA-N lead(0) Chemical compound [Pb] WABPQHHGFIMREM-UHFFFAOYSA-N 0.000 claims description 4
- JFALSRSLKYAFGM-AHCXROLUSA-N uranium-234 Chemical compound [234U] JFALSRSLKYAFGM-AHCXROLUSA-N 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims 1
- 238000005259 measurement Methods 0.000 description 13
- 239000007789 gas Substances 0.000 description 12
- 230000004907 flux Effects 0.000 description 10
- 238000001514 detection method Methods 0.000 description 4
- 230000004992 fission Effects 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 1
- 229910000889 permalloy Inorganic materials 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
- H01J47/12—Neutron detector tubes, e.g. BF3 tubes
- H01J47/1227—Fission detectors
- H01J47/1233—Ionisation chambers
Landscapes
- Physics & Mathematics (AREA)
- High Energy & Nuclear Physics (AREA)
- Measurement Of Radiation (AREA)
Description
【発明の詳細な説明】
本発明は原子炉内の中性子束密度を計測するた
めの核分裂形電離箱・中性子検出器に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fission chamber/neutron detector for measuring neutron flux density within a nuclear reactor.
たとえば沸騰水形原子炉の中性子束レベルは広
い測定レンジを持つているが、その上限の中性子
束は新型炉の出現または原子炉が大型化するなか
で、たとえば２×1014nvと高くなつてきている。 For example, the neutron flux level of a boiling water nuclear reactor has a wide measurement range, but the upper limit of the neutron flux has increased to, for example, 2×10 14 nv as new types of reactors emerge or reactors become larger. ing.
しかしながら、中性子源を使用して計装系の動
作を確認しなければならないので、低領域の計測
レベルは変えることができないにもかかわらず、
計測範囲は広くなる傾向になつている。 However, since the operation of the instrumentation system must be confirmed using a neutron source, the measurement level in the low region cannot be changed.
The measurement range tends to become wider.
一般に原子炉の中性子計装は３つの測定手段を
組合せている。その１つは起動系による計測で、
パルス計数により中性子レベルの測定、２番目は
中間系による計測でキヤンベル法による中性子束
レベルの測定、３番目は出力系による計測で、直
流電流による中性子束レベルの測定である。 Generally, neutron instrumentation for nuclear reactors combines three measurement means. One of them is measurement by the startup system,
The neutron level is measured by pulse counting, the second is the measurement by the intermediate system and the neutron flux level is measured by the Campbell method, and the third is the measurement by the output system and the neutron flux level is measured by DC current.
なお、原子炉が大型化しても起動系はそのまま
の感度が必要で、中間系および出力系の計測範囲
を広げなければならない。 Note that even if the reactor becomes larger, the startup system must maintain the same sensitivity, and the measurement range of the intermediate system and output system must be expanded.
しかしながら、計測範囲を広げることは種々の
問題を生じ困難である。たとえば特に炉心内に中
性子検出器を装荷する場合、装荷するスペースが
決められているため、検出器の形状を大きくする
ことができず、必然的に大きさが制限されること
になる。 However, expanding the measurement range causes various problems and is difficult. For example, especially when loading a neutron detector into a reactor core, the space for loading is fixed, so the shape of the detector cannot be increased, and its size is inevitably limited.
従来の中性子検出器は、たとえば第１図に示す
如く、信号電極としての陽極１およびガイド電極
としての陰極２とが、その両端を絶縁体３，４で
気密封止された形状であり、その陰極２の内部に
電離ガスが充填されている。また陰極２の内面に
は中性子変換物質５として、たとえばウラン235
がコーテイングされている。このように構成され
た中性子検出器の動作原理としては、中性子が入
射するとウラン235が核分裂反応し、生成した核
分裂破片が電離ガス中を走行する。この時電離ガ
スは電離され電子およびイオン対ができる。ここ
で外部電源６から両電極１，２に加えられた電界
により電子およびイオンはそれぞれの電極１，２
に収集され、信号となり電流計７で測定される。
この信号電流は陰極２内に入射した中性子束に比
例する。なお、図中８はアース用リード線であ
る。 As shown in FIG. 1, for example, a conventional neutron detector has a shape in which an anode 1 as a signal electrode and a cathode 2 as a guide electrode are hermetically sealed at both ends with insulators 3 and 4. The inside of the cathode 2 is filled with ionized gas. In addition, the inner surface of the cathode 2 contains a neutron conversion material 5, such as uranium 235.
is coated. The operating principle of a neutron detector configured in this way is that when neutrons are incident, uranium-235 undergoes a nuclear fission reaction, and the generated fission fragments travel through ionized gas. At this time, the ionized gas is ionized to form electron and ion pairs. Here, due to the electric field applied to both electrodes 1 and 2 from the external power source 6, electrons and ions are
is collected as a signal and measured by an ammeter 7.
This signal current is proportional to the neutron flux incident on the cathode 2. Note that 8 in the figure is a grounding lead wire.
このようにして中性子検出器の出力電流を電流
計７で計測することにより入射中性子束を知るこ
とが可能となる。 In this way, by measuring the output current of the neutron detector with the ammeter 7, it becomes possible to know the incident neutron flux.
しかしながら、入射中性子束が大きくなると陽
極１の近傍にイオンによる空間電荷が生じ、第３
図のグラフの曲線ａで示したように１×1014nv附
近から比例関係が成立しなくなる。なお、図中破
線ｂは理想特性線図である。つまり飽和特性が得
られないことになる。飽和電圧Vsは第１図に示
した検出器の場合、以下の式で求められる。 However, when the incident neutron flux increases, a space charge is generated by ions near the anode 1, and a third
As shown by curve a in the graph of the figure, the proportional relationship no longer holds true from around 1×10 14 nv. Note that the broken line b in the figure is an ideal characteristic diagram. In other words, saturation characteristics cannot be obtained. In the case of the detector shown in FIG. 1, the saturation voltage Vs is determined by the following formula.
Vs＝Ｋ・（Is・Ｐ／μV）1/2・a2〔（ｂ／ａ）2−１
−2ln
（ｂ／ａ）〕 ……(1)
ここで、Ｋは定数、Isは飽和電流（Ａ）、Ｐは
封入ガス圧（atm）、μはイオン易移度（cm2/V・s
ｅｃ・ａｔｍ）、Ｖは有効容積（cm3）、ａは陽極半径
（cm）ｂは陰極内半径（cm）である。 Vs=K・(Is・P/μV) 1/2・a 2 [(b/a) 2 −1
−2ln (b/a)] ...(1) Here, K is a constant, Is is the saturation current (A), P is the filled gas pressure (atm), and μ is the ion mobility (cm 2 /V・s
ec・atm), V is the effective volume (cm 3 ), a is the anode radius (cm), and b is the cathode inner radius (cm).
一定の印加電圧で使用する場合、飽和電流Is
（Ａ）は限定される。このことは計測可能な中性
子束の上限は限定されることになる。つまり中性
子検出器の寸法、形状、封入ガス圧およびガスの
種類、中性子感度等を変えなければ、計測上限を
延ばすことは不可能である。 When used with a constant applied voltage, the saturation current Is
(A) is limited. This means that the upper limit of measurable neutron flux is limited. In other words, it is impossible to extend the upper limit of measurement without changing the dimensions, shape, pressure and type of gas, neutron sensitivity, etc. of the neutron detector.
しかしながら、前述したように炉内中性子束を
検出するためには中性子検出器の外径を変えるこ
とは好ましくないなどの欠点がある。 However, as described above, there are drawbacks such as the fact that it is not desirable to change the outer diameter of the neutron detector in order to detect the in-core neutron flux.
本発明は上記欠点を除去するためになされたも
ので、従来をほぼ同様の外径寸法で、しかも外観
形状が変わることなく上限の計測範囲を約２倍に
できる核分裂形電離箱・中性子検出器を提供する
ことにある。 The present invention has been made to eliminate the above-mentioned drawbacks, and is a fission type ionization chamber/neutron detector that can approximately double the upper limit measurement range without changing the external shape and having almost the same outer diameter as the conventional one. Our goal is to provide the following.
すなわち、本発明は両端が絶縁体で気密に封止
され、かつ電離ガスが封入された第１のガイド電
極と、この第１のガイド電極内に前記絶縁体を介
して同軸的に固定された通気性を有する信号電極
と、この信号電極内に前記絶縁体を介して同軸的
に配置された第２のガイド電極と、前記第１のガ
イド電極の内面と前記信号電極の外面との少くと
も一方の面ならびに前記信号電極の内面と前記第
２のガイド電極の外面との少くとも一方の面にコ
ーテイングされた中性子変換物質層と、前記信号
電極および各々のガイド電極からそれぞれ導出さ
れ該両電極間に電圧を印加するリード線とを具備
したことを特徴とする中性子検出器である。 That is, the present invention includes a first guide electrode whose both ends are hermetically sealed with an insulator and filled with ionized gas, and a first guide electrode which is coaxially fixed within the first guide electrode via the insulator. a signal electrode having air permeability; a second guide electrode disposed coaxially within the signal electrode via the insulator; and at least an inner surface of the first guide electrode and an outer surface of the signal electrode. a neutron conversion material layer coated on one surface and at least one surface of the inner surface of the signal electrode and the outer surface of the second guide electrode; The neutron detector is characterized in that it includes a lead wire between which a voltage is applied.
以下、本発明に係る中性子検出器の一実施例を
第２図により詳しく説明する。 Hereinafter, one embodiment of the neutron detector according to the present invention will be explained in detail with reference to FIG.
第２図において信号電極となる陽極２１の外側
に第１のガイド電極としての陰極２２および前記
陽極２１の内側に第２のガイド電極としての陰極
２３とを備え、これら３つの電極２１，２２，２
３を同軸的に配置して絶縁体２４，２５で気密に
保持している。 In FIG. 2, a cathode 22 as a first guide electrode is provided on the outside of an anode 21 serving as a signal electrode, and a cathode 23 as a second guide electrode is provided on the inside of the anode 21, and these three electrodes 21, 22, 2
3 are arranged coaxially and held airtight by insulators 24 and 25.
陽極２１および陰極２２の内面には核分裂物質
層２６としてウラン235がコーテイングされてい
る。ここで陽極２１と陰極２２および陽極２１と
陰極２３の２ケ所に存在する空隙部２７，２８に
はそれぞれ電離ガスが充填されている。 The inner surfaces of the anode 21 and the cathode 22 are coated with uranium 235 as a fissile material layer 26. Here, the two gaps 27 and 28 between the anode 21 and the cathode 22 and between the anode 21 and the cathode 23 are filled with ionized gas, respectively.
陽極２１と陰極２２間の有感部分２８は従来の
検出器と外形が同寸法であり、ここだけの性能は
変わらない。しかし陽極２１と陰極２３の間にも
う１つの検出部分２７が存在するので検出器全体
の検出感度を従来と同じにすれば有感部分２７が
増加するため電流密度を小さくすることができ
る。たとえば中性子検出器の外径が11mmφ、肉厚
0.45mmのものについてどの位、電流密度が小さく
なるかを求める。検出器の外径11mmφ、陰極２２
の内径10mmφ、陽極２１の外径9.5mmφ、内径９
mmφ、陰極２３の外径8.5mmφとした時、陽極２
１と陰極２２との間の有感部の飽和電圧Vsは前
記式(1)によつて求められ、陽極２１と陰極２３の
間の有感部２７は外部電極が正で、内部電極が負
で、極性が異なるため飽和電圧Vsは以下の式に
よつて求められる。 The sensitive part 28 between the anode 21 and the cathode 22 has the same external dimensions as the conventional detector, and the performance of this part remains the same. However, since there is another detection part 27 between the anode 21 and the cathode 23, if the detection sensitivity of the entire detector is kept the same as in the conventional case, the current density can be reduced because the sensitive part 27 increases. For example, the outer diameter of a neutron detector is 11mmφ, and the wall thickness is
Find out how much the current density decreases for the 0.45mm one. Detector outer diameter 11mmφ, cathode 22
The inner diameter of the anode 21 is 10 mmφ, the outer diameter of the anode 21 is 9.5 mmφ, the inner diameter is 9
mmφ, and when the outer diameter of the cathode 23 is 8.5 mmφ, the anode 2
The saturation voltage Vs of the sensitive part between the anode 21 and the cathode 22 is determined by the above equation (1). Since the polarities are different, the saturation voltage Vs can be found by the following formula.
Vs＝Ｋ・（Is・Ｐ／μV）1/2・a2・〔（ｂ／ａ）2｛2ln
（ｂ／ａ）−
１｝＋１〕 ……(2)
（ただし、Ｋ、Is、Ｐ、μ、Ｖ、ａ、ｂは式(1)の
所で説明している。）
ここで、飽和電圧Vsを一定にした時の従来検
出器の出力電流をIOとし、本発明はの陽極２１と
陰極２２との間の有感部２８における出力電流を
IN1、陽極２１と陰極２３との間の有感部２７に
おける出力電流をIN2とした場合、従来検出器と
検出感度を同じにすればIO＝IN1＋IN2の関係が得
られる。Vs=K・(Is・P/μV) 1/2・a 2・[(b/a) 2 {2ln
(b/a)-1}+1] ...(2) (However, K, Is, P, μ, V, a, and b are explained in equation (1).) Here, the saturation voltage The output current of the conventional detector when Vs is kept constant is I O , and the output current in the sensitive part 28 between the anode 21 and the cathode 22 of the present invention is
If I N1 is the output current in the sensitive section 27 between the anode 21 and the cathode 23, and I N2 is the output current in the sensitive section 27 between the anode 21 and the cathode 23, the relationship I O =I N1 +I N2 can be obtained if the detection sensitivity is the same as that of the conventional detector.
ここで、式(1)、(2)に検出器の寸法、容積を入れ
てIO、IN1、IN2の関係を求めるとIN1／IO＝0.52、IN2／
IO
＝0.48となる。このことは２つの有感部分を有す
ることにより、同じ検出部の電流量が52％に低減
され、第４図に示したように計測範囲が1.92倍だ
け延ばすことが可能となる。このように２重同軸
構成にして第１図の陽極１の内部の無感部分に第
２図に示す如くもう１個所の有感部分２７を設け
ることにより、無感部分が有感部分となるため中
性子検出器の計測範囲を広げることができる効果
がある。 Here, by inserting the dimensions and volume of the detector into equations (1) and (2) to find the relationship between I O , I N1 , and I N2 , I N1 /I O =0.52, I N2 /
I O =0.48. This means that by having two sensitive parts, the amount of current in the same detection part is reduced to 52%, making it possible to extend the measurement range by 1.92 times as shown in FIG. In this way, by creating a double coaxial configuration and providing another sensitive part 27 as shown in FIG. 2 in the insensitive part inside the anode 1 shown in FIG. 1, the insensitive part becomes a sensitive part. This has the effect of expanding the measurement range of the neutron detector.
ここで述べた実施例は陰極２２、陽極２１の内
面にウラン235をコーテイングしたが、これは陽
極２１の両面、陰極２３の外面でも可能である。 In the embodiment described here, the inner surfaces of the cathode 22 and anode 21 are coated with uranium 235, but this can also be done on both surfaces of the anode 21 and the outer surface of the cathode 23.
また検出器の寿命を延ばすためにはウラン235
を単独用いるよりもウラン234とウラン235との混
合物を使用することができる。 In addition, to extend the life of the detector, uranium-235
Rather than using uranium-234 and uranium-235 alone, a mixture of uranium-234 and uranium-235 can be used.
なお、電離ガスとしてはヘリウム、ネオン、ア
ルゴンなどの希ガスを使用することができる。電
極の材質にはステンレス鋼、チタン、パーマロイ
などの金属を使用することができる。更に空隙部
２７，２８内を等ガス圧とするため陽極２１を通
気性としてもよく、また気密性として空隙部２
７，２８内に別個に等ガス圧の電離ガスを充填す
るようにしてもよい。 Note that rare gases such as helium, neon, and argon can be used as the ionized gas. As the material of the electrode, metals such as stainless steel, titanium, permalloy, etc. can be used. Furthermore, the anode 21 may be made breathable in order to equalize the gas pressure in the gaps 27 and 28, and the gap 2 may be made airtight.
7 and 28 may be filled with ionized gas of equal gas pressure separately.
第１図は従来の中性子検出器を示す断面図、第
２図は本発明に係る中性子検出器の一実施例を示
す断面図、第３図は第１図における特性図、第４
図は第２図における特性図である。
１，２１……陽極、２，２２，２３……陰極、
３，４，２４，２５……絶縁体、５，２６……中
性子変換物質層、６……高圧電源、７……電流
計、８……リード線（アース線）、２７，２８…
…有感部。
FIG. 1 is a sectional view showing a conventional neutron detector, FIG. 2 is a sectional view showing an embodiment of a neutron detector according to the present invention, FIG. 3 is a characteristic diagram in FIG. 1, and FIG.
The figure is a characteristic diagram in FIG. 2. 1, 21... anode, 2, 22, 23... cathode,
3, 4, 24, 25... Insulator, 5, 26... Neutron conversion material layer, 6... High voltage power supply, 7... Ammeter, 8... Lead wire (ground wire), 27, 28...
...Sensitive part.
Claims (1)
スが封入された第１のガイド電極と、この第１の
ガイド電極内に前記絶縁体を介して同軸的に固定
された信号電極と、この信号電極内に前記絶縁体
を介して同軸的に配置された第２のガイド電極
と、前記第１のガイド電極の内面と前記信号電極
の外面との少くとも一方の面ならびに前記信号電
極の内面と前記第２のガイド電極の外面との少く
とも一方の面にコーテイングされた同種類の中性
子変換物質層と、前記信号電極および各々のガイ
ド電極からそれぞれ導出され該両電極間に電圧を
印加するリード線とを具備したことを特徴とする
中性子検出器。 ２ 中性子変換物質としてウラン235またはウラ
ン234とウラン235との混合物が、電離ガスとして
希ガスが使用されることを特徴とする特許請求の
範囲第１項記載の中性子検出器。[Claims] 1. A first guide electrode hermetically sealed at both ends with an insulator and filled with ionized gas, and coaxially fixed within the first guide electrode via the insulator. a second guide electrode disposed coaxially within the signal electrode via the insulator, and at least one of the inner surface of the first guide electrode and the outer surface of the signal electrode. a neutron converting material layer of the same type coated on at least one surface of the signal electrode and the outer surface of the second guide electrode; A neutron detector characterized by comprising a lead wire for applying a voltage between electrodes. 2. The neutron detector according to claim 1, wherein uranium-235 or a mixture of uranium-234 and uranium-235 is used as the neutron conversion substance, and a rare gas is used as the ionizing gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6264281A JPS57178172A (en) | 1981-04-27 | 1981-04-27 | Neutron detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6264281A JPS57178172A (en) | 1981-04-27 | 1981-04-27 | Neutron detector |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57178172A JPS57178172A (en) | 1982-11-02 |
| JPS646709B2 true JPS646709B2 (en) | 1989-02-06 |
Family
ID=13206180
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6264281A Granted JPS57178172A (en) | 1981-04-27 | 1981-04-27 | Neutron detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57178172A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008089310A (en) * | 2006-09-29 | 2008-04-17 | Toshiba Corp | Radiation measuring apparatus and its measuring method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5127693A (en) * | 1974-08-30 | 1976-03-08 | Hitachi Ltd |
-
1981
- 1981-04-27 JP JP6264281A patent/JPS57178172A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57178172A (en) | 1982-11-02 |
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