JPH032693A - Removing method of photoneutron effect in measuring device of boric acid concentration - Google Patents
Removing method of photoneutron effect in measuring device of boric acid concentrationInfo
- Publication number
- JPH032693A JPH032693A JP1136227A JP13622789A JPH032693A JP H032693 A JPH032693 A JP H032693A JP 1136227 A JP1136227 A JP 1136227A JP 13622789 A JP13622789 A JP 13622789A JP H032693 A JPH032693 A JP H032693A
- Authority
- JP
- Japan
- Prior art keywords
- concentration
- heavy water
- iph
- neutron
- photoneutron
- 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
- 238000000034 method Methods 0.000 title claims description 12
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 title claims description 9
- 239000004327 boric acid Substances 0.000 title claims description 9
- 230000000694 effects Effects 0.000 title abstract description 5
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims abstract description 68
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 230000001419 dependent effect Effects 0.000 claims description 3
- 238000010521 absorption reaction Methods 0.000 abstract description 8
- 238000012937 correction Methods 0.000 abstract description 8
- 230000005251 gamma ray Effects 0.000 abstract description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052796 boron Inorganic materials 0.000 abstract description 3
- 238000005259 measurement Methods 0.000 description 8
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000003321 amplification Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000003199 nucleic acid amplification method Methods 0.000 description 2
- 230000002285 radioactive effect Effects 0.000 description 2
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052805 deuterium Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000011160 research Methods 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
Landscapes
- Monitoring And Testing Of Nuclear Reactors (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
重水炉において減速材として使用される重水には中性子
吸収のため、はう酸（１０Ｂ）が含まれている。そして
重水中のほう酸濃度を変えることによって１重水炉にお
ける反応度が制御される。従って、重水中のほう酸の濃
度測定は極めて重要である。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) Heavy water used as a moderator in heavy water reactors contains oxalic acid (10B) to absorb neutrons. The reactivity in a single heavy water reactor is controlled by changing the concentration of boric acid in heavy water. Therefore, measuring the concentration of boric acid in heavy water is extremely important.
本発明はこのような重水中のほう酸濃度測定器における
光中性子の影響除去方法に関するものである６
（従来技術）
第２図を参照してほう酸濃度測定器について概略説明す
る。第２図に於て１は測定容器、２は測定容器１の外部
を囲む反射兼遮蔽体である。３は重水入口、４は中性子
計測器、５は中性子線源である。この線源５からの中性
子は前記反射兼遮蔽体によって反射され、中性子を容器
内に封じ込めて外部漏洩を防止すると同時に中性子を外
部に逃さないで効率的に利用するようになっている。The present invention relates to a method for removing the influence of photoneutrons in such an instrument for measuring the concentration of boric acid in heavy water.6 (Prior Art) The instrument for measuring the concentration of boric acid in heavy water will be briefly described with reference to FIG. In FIG. 2, 1 is a measuring container, and 2 is a reflecting/shielding body surrounding the outside of the measuring container 1. 3 is a heavy water inlet, 4 is a neutron measuring device, and 5 is a neutron beam source. The neutrons from the radiation source 5 are reflected by the reflecting/shielding body, and the neutrons are sealed in the container to prevent leakage to the outside, and at the same time, the neutrons are efficiently used without escaping to the outside.
そして、重水人口３からほう酸を含んだ重水を測定容器
１内に送り込み、容器頂部から中性子を照射し、重水り
によって減速され”Ｂに吸収されない中性子ｎ□を中性
子計測器４で検出するようになっている。Then, heavy water containing boric acid is sent from the heavy water tank 3 into the measurement container 1, neutrons are irradiated from the top of the container, and the neutrons n□ that are decelerated by the heavy water tank and not absorbed by "B" are detected by the neutron measuring instrument 4. It has become.
中性子線源５の２５２Ｃｆから中性子が放射されると、
測定容器１内では重水りによって減速された中性子と減
速されない中性子ｎとが混在している。When neutrons are emitted from 252Cf of the neutron source 5,
Inside the measurement container 1, neutrons decelerated by the heavy water tank and neutrons n that are not decelerated coexist.
又重水りで減速された中性子のうちには、さらに重水中
のほう酸”Ｂに吸収される中性子ｎ８がある。従って、
中性子線源５から放射される中性子の総量のうち、計測
器４にて計測される量は重水りであまり減速されないで
計測器４に達する中性子ｎと重水りで減速されて計測器
４に達する中性子ｎＱの和（ｎ＋ｎｏ）となる。Among the neutrons slowed down by heavy water, there is also neutron n8, which is absorbed by boric acid "B" in heavy water. Therefore,
Of the total amount of neutrons emitted from the neutron source 5, the amount measured by the measuring device 4 is the neutron n that reaches the measuring device 4 without being slowed down much by the heavy water tank, and the neutrons n that are decelerated by the heavy water tank and reach the measuring device 4. The sum of neutrons nQ is (n+no).
一方、重水中には不純物である”Ｎａ、 ’“Ｍｎが存
在するが、これら”Ｎａや” Ｍ ｎから発生する高エ
ネルギーγ線の一部は重水りと反応して光中性子ｎｐを
発生する。On the other hand, impurities "Na" and "Mn" exist in heavy water, and some of the high-energy γ-rays generated from these "Na" and "Mn" react with the heavy water to generate photoneutrons np. .
したがって、計測器４では重水りに減速された中性子の
うち”Ｂに吸収されなかった中性子ｎ。Therefore, the measuring instrument 4 calculates the number of neutrons that were not absorbed by B among the neutrons that were decelerated by the heavy water tank.
と、あまり減速されない中性子ｎ及び光中性子ｎｐの３
種の中性子ｎ ＋ ｎｌ）＋ ｎｐが計測されることに
なる。and 3 of neutron n and photoneutron np, which are not slowed down much.
The seed neutrons n + nl) + np will be measured.
計測器４で計測される光中性子ｎＰは２Ｓ２ｃｆからの
中性子でなく１発生源を異にしているので、計測器４で
の測定値の誤差となる中性子である。The photoneutrons nP measured by the measuring instrument 4 are not neutrons from 2S2cf but come from a different source, so they are neutrons that cause an error in the measurement value by the measuring instrument 4.
上述した光中性子の影響を除く方法としてＣｄフィルタ
付きの計数管を用いる方法がある。Ｃｄフィルタ付きの
計数管は熱外中性子のみを測定するため、”Ｂ濃度の依
存性は小さく、Ｃｄフィルタ付きの計数管に入る光中性
子を求めることができるので、この値を基に光中性子の
影響を補正できる。There is a method of using a counter equipped with a Cd filter as a method of removing the influence of photoneutrons mentioned above. Since the counter with a Cd filter measures only epithermal neutrons, the dependence on the B concentration is small, and the photoneutrons entering the counter with a Cd filter can be determined. Based on this value, the photoneutrons can be calculated. The effects can be corrected.
しかし”Ｂ濃度が高くなると”Ｈによる吸収が無視でき
ず、Ｃｄフィルタ付きの計数管に入る光中性子を測定す
る場合も、１０Ｂ濃度の影響を考慮する必要がある。こ
のため補正の処理が煩雑となる。又重水中で熱外中性子
を測定しているので、計数率が低く、統計誤差をおさえ
るためには測定時間を長くする必要がある。However, when the B concentration increases, absorption by H cannot be ignored, and even when measuring photoneutrons entering a counter equipped with a Cd filter, it is necessary to consider the influence of the 10B concentration. Therefore, the correction process becomes complicated. Furthermore, since epithermal neutrons are measured in heavy water, the counting rate is low, and in order to suppress statistical errors, it is necessary to lengthen the measurement time.
（発明が解決しようとする課題）
上述したように、重水中の”Ｂ濃度のオンライン測定の
ため、中性子源から出た中性子が重水で減速され、減速
された中性子が１１１Ｂに吸収されることを利用した測
定器を開発するに当り１重水中には放射性不純物がある
が、この内２４Ｎａ、 ”Ｍｎからのγ線の一部は重水
と反応して光中性子を生成する。この光中性子が１０Ｂ
濃度測定に於て誤差要因となるので、この光中性子の影
響を補正する方法を提供しようとするものである。(Problem to be Solved by the Invention) As mentioned above, in order to measure the B concentration in heavy water on-line, it is assumed that the neutrons emitted from the neutron source are decelerated by the heavy water, and the decelerated neutrons are absorbed by 111B. When developing the measuring device used, we discovered that there are radioactive impurities in heavy water, and some of the gamma rays from 24Na and Mn react with heavy water to generate photoneutrons. This photoneutron is 10B
Since this is a cause of error in concentration measurement, the present invention aims to provide a method for correcting the influence of photoneutrons.
（発明による課題の解決手段）
重水中の不純物から発生するγ線量を測定し、これをＩ
Ｐｈ＝Ｎ（χ）Ｉｙ
ただし、Ｉｐｈ；光中性子量
Ｎ（χ）；１１′Ｂ濃度の依存する定数工γ：γ線の測
定値
で計算して光中性子量に換算し、中性子計数管でのカウ
ント値からＩｐｈを差引くことにより、中性子源よりの
熱中性子量のみを算出することを特徴とする。(Means for solving problems by invention) Measure the amount of γ-rays generated from impurities in heavy water, and
Ph=N(χ)Iy However, Iph: Photoneutron amount N(χ); 11′B concentration dependent constant γ: Calculated from the measured value of γ rays, converted to photoneutron amount, and calculated using a neutron counter. The method is characterized in that only the amount of thermal neutrons from the neutron source is calculated by subtracting Iph from the count value of .
（実施例）
前述したように、重水中には放射性不純物として”Ｎａ
、”Ｍｎ、”Ｃｏ等がありγ線を放出する。(Example) As mentioned above, heavy water contains “Na” as a radioactive impurity.
, ``Mn,'' Co, etc., and emit γ-rays.
２．２ＭｅＶ以上のγ線では重水中の重水素との（γｏ
ｎ）反応により中性子が生成され、これが誤差の原因と
なる。For γ-rays of 2.2 MeV or higher, the interaction with deuterium in heavy water (γo
n) The reaction produces neutrons, which cause errors.
本発明では重水中のγ線量を測定し、これを光中性子量
に換算する。ここで１Ｊによるγ線の吸収の程度を概算
する。γ線の吸収は”Ｂでも１１Ｂでも変りなく、ホウ
素１Ｍ子あたりの全断面積が約０．７４ｂａｒｎｓ （
２Ｍｅ ｖにおいて）、質量吸収係数にして０ 、０４
１ （！！Ｔ ／ ｇになる。従って、例えば、重水中
（密度１．１ｇ／ａｆ）の全ホウ素濃度が１５０ｐｐｍ
のとき、ＩＱ１１厚さあたりのγ線の吸収は１００万分
の６の程度に過ぎず、殆ど無視できる。In the present invention, the amount of gamma rays in heavy water is measured and converted into the amount of photoneutrons. Here, the degree of absorption of gamma rays by 1 J will be roughly estimated. The absorption of γ-rays is the same whether it is ``B'' or 11B, and the total cross-sectional area per 1M boron is approximately 0.74 barns (
(at 2Me v), the mass absorption coefficient is 0,04
1 (!!T/g. Therefore, for example, if the total boron concentration in heavy water (density 1.1 g/af) is 150 ppm
At this time, the absorption of gamma rays per IQ11 thickness is only about 6/1,000,000 and can be almost ignored.
これからγ線の測定値Ｉγと中性子計数管で計測される
光中性子Ｉｐｈは
Ｉｐｈ＝Ｎ（χ）■γ ・・・（１）とできる。From this, the measured value of γ-rays Iγ and the photoneutrons Iph measured by the neutron counter can be expressed as Iph=N(χ)■γ (1).
ここでＮ（χ）：”Ｂ濃度に依存する定数定数ＮがＬＯ
Ｂ濃度の関数とするのは、光中性子も減速され１０Ｂに
吸収される効果を考慮したためである。補正はカウンタ
４で測定された計数からＩＰｈを差し引くことで、中性
子源からの熱中性子量のみを算出でき、”Ｂ濃度を求め
ることができる。Here, N(χ): "A constant N that depends on the B concentration is LO
The reason for making it a function of the B concentration is to take into consideration the effect that photoneutrons are also slowed down and absorbed by 10B. For correction, by subtracting IPh from the count measured by the counter 4, only the amount of thermal neutrons from the neutron source can be calculated, and the "B concentration" can be determined.
第１図は本発明方法を実施する装置の一例を示し、６は
中性子計数管４からの信号を処理する信号処理装置、７
は演算装置である。８はＮａｒシンチレータ付き光電子
増倍管で、重水中のγ線量を測定し、前置増巾器９、波
高増巾弁別器１０を介し光中性子量に換算し、前記演算
袋＠７で熱中性子量を算出するようになっている。FIG. 1 shows an example of a device for carrying out the method of the present invention, in which 6 is a signal processing device for processing signals from a neutron counter 4;
is a computing device. 8 is a photomultiplier tube equipped with a Nar scintillator, which measures the amount of γ-rays in heavy water, converts it into a photoneutron amount via a preamplifier 9 and a pulse height amplification discriminator 10, and converts it into a photoneutron amount using the calculation bag @7. The amount is calculated.
（効果）
１）本発明方法によれば、”Ｂ濃度が高い場合にも、光
中性子の生成の情報は１６Ｂ濃度に影響されずに得るこ
とができ、補正の処理が簡単になった。(Effects) 1) According to the method of the present invention, even when the B concentration is high, information on the generation of photoneutrons can be obtained without being affected by the 16B concentration, and the correction process is simplified.
２）従来の方式の１つであるＣｄフィルタを使って計測
する熱外中性子による補正では、１０Ｂによる熱外中性
子の吸収断面積が１９０ｂａｒｎｓ （ａｔｌｏｅＶ）
と大きいので、Ｃｄフィルタ付きの計数管の計数が”Ｂ
濃度の関数となり、Ｃｄなしの中性子計数管で計測され
るはずの光中性子Ｉｐｈは、Ｉ ｐｈ＝ Ｎ’ （ｚ
）（Ｉ ｃ −Ｉ ｃｏ（χ））・−−（２）ここで、
Ｎ’（χ）：１０Ｂ濃度に依存する定数。2) In correction using epithermal neutrons measured using a Cd filter, which is one of the conventional methods, the absorption cross section of epithermal neutrons by 10B is 190 barns (atloeV)
Since the counter tube with Cd filter is large, the count of the counter tube with Cd filter is "B"
The photoneutron Iph, which is a function of the concentration and should be measured with a neutron counter without Cd, is I ph= N' (z
)(I c −I co(χ))・−(2) Here,
N'(χ): constant dependent on 10B concentration.
Ｉｃ：Ｃｄフィルタ付きの計数管で測
定される熱外中性子
Ｉｃｏ（χ）：中性子源による熱外中性子（１０Ｂに依
存する）
の様に示される。Ic: Epithermal neutrons measured with a counter with Cd filter Ico(χ): Epithermal neutrons from the neutron source (depending on 10B).
このようにＣｄフィルタを使う場合補正が煩雑になる。When a Cd filter is used in this way, correction becomes complicated.
これに対し本発明方法は（γ＋ｎ）反応の結果生ずるγ
線を直に測定するので、計数率も高く、短時間の測定で
統計誤差の小さい測定が可能となった・In contrast, in the method of the present invention, the γ produced as a result of the (γ+n) reaction
Because the line is directly measured, the counting rate is high, and measurement with small statistical errors is possible in a short time.
第１図は本発明に係るγ線測定による光中性子補正シス
テムを示す。
第２図はほう酸濃度測定方法の原理図。
図において；
１ 測定容器 ２ 反射兼遮蔽体３ 重水人口
４ 中性子計測器中性子線源
演算装置
前置増巾器
換算器
信号処理装置
光電子増倍管
１０ 波高増巾弁別器
以上
出願人 日本原子力研究所（外１名）
代理人 弁理士 大 橋 勇
第 １ 図
Ｎａ１Ｖンナレー／FIG. 1 shows a photoneutron correction system using gamma ray measurement according to the present invention. Figure 2 is a diagram showing the principle of the boric acid concentration measurement method. In the diagram; 1 measurement container 2 reflection/shielding body 3 heavy water population
4 Neutron measuring device Neutron source calculation device Preamplifier converter Signal processing device Photomultiplier tube 10 Pulse height amplification discriminator Applicant: Japan Atomic Energy Research Institute (1 other person) Agent: Patent attorney Isamu Ohashi 1st Figure Na1Vnnare/
Claims (1)
＿ｐ＿ｈ＝Ｎ（χ）Ｉγ ただし、Ｉ＿ｐ＿ｈ；光中性子量 Ｎ（χ）；＾１＾０Ｂ濃度の依存する定数 Ｉγ；γ線の測定値 で計算して光中性子量に換算し、中性子計数管でのカウ
ント値からＩ＿ｐ＿ｈを差引くことにより、中性子源よ
りの熱中性子量のみを算出することを特徴とするほう酸
濃度測定器における光中性子の影響除去方法。[Claims] The amount of γ-rays generated from impurities in heavy water is measured and
_p_h=N(χ)Iγ However, I_p_h; amount of photoneutrons N(χ); ^1^0B concentration-dependent constant Iγ; calculated using the measured value of γ-rays, converted to the amount of photoneutrons, and calculated using a neutron counter. A method for removing the influence of photoneutrons in a boric acid concentration measuring instrument, characterized in that only the amount of thermal neutrons from a neutron source is calculated by subtracting I_p_h from the count value of .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1136227A JPH032693A (en) | 1989-05-31 | 1989-05-31 | Removing method of photoneutron effect in measuring device of boric acid concentration |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1136227A JPH032693A (en) | 1989-05-31 | 1989-05-31 | Removing method of photoneutron effect in measuring device of boric acid concentration |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH032693A true JPH032693A (en) | 1991-01-09 |
Family
ID=15170262
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1136227A Pending JPH032693A (en) | 1989-05-31 | 1989-05-31 | Removing method of photoneutron effect in measuring device of boric acid concentration |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH032693A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4736573B2 (en) * | 2005-07-06 | 2011-07-27 | パナソニック株式会社 | Windmill |
-
1989
- 1989-05-31 JP JP1136227A patent/JPH032693A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4736573B2 (en) * | 2005-07-06 | 2011-07-27 | パナソニック株式会社 | Windmill |
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