JPH0555838B2 - - Google Patents
Info
- Publication number
- JPH0555838B2 JPH0555838B2 JP62248111A JP24811187A JPH0555838B2 JP H0555838 B2 JPH0555838 B2 JP H0555838B2 JP 62248111 A JP62248111 A JP 62248111A JP 24811187 A JP24811187 A JP 24811187A JP H0555838 B2 JPH0555838 B2 JP H0555838B2
- Authority
- JP
- Japan
- Prior art keywords
- neutrons
- photoneutrons
- neutron
- heavy water
- amount
- 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 - Lifetime
Links
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims description 58
- 238000005259 measurement Methods 0.000 claims description 17
- 239000004327 boric acid Substances 0.000 claims description 14
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 5
- 239000012535 impurity Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 125000005619 boric acid group Chemical group 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000001637 plasma atomic emission spectroscopy Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000002285 radioactive effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- KGBXLFKZBHKPEV-BJUDXGSMSA-N trihydroxyborane Chemical compound O[10B](O)O KGBXLFKZBHKPEV-BJUDXGSMSA-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
Landscapes
- Monitoring And Testing Of Nuclear Reactors (AREA)
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、ほう酸（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
よつて、重水炉における反応度が制御されてい
る。従つて、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 boric acid ( 10 B) for neutron absorption. By changing the concentration of boric acid in heavy water, the reactivity in the heavy water reactor is controlled. 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。 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.
（従来技術）
第６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６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
体によつて反射され、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
さないで効果的に利用するようになつている。(Prior Art) A boric acid concentration measuring device will be briefly described with reference to FIG. In FIG. 6, 1 is a measurement container, and 2 is a reflection/shielding body surrounding the outside of the measurement 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 effectively used without escaping to the outside.
そして、重水入口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
照射し重水によつて減速され10Bに吸収されない
中性子を中性子計測器４で検出するようになつて
いる。しかしこれまでに原子炉系統重水中の10B
濃度測定は例がなく特に考えられていなかつた。 Then, heavy water containing boric acid is fed into the measurement container 1 from the heavy water inlet 3, neutrons are irradiated from the top of the container, and the neutrons that are decelerated by the heavy water and not absorbed by the 10 B are detected by the neutron measuring instrument 4. There is. However, up to now 10 B in heavy water in the reactor system
There were no examples of concentration measurement, and no particular consideration was given to it.
（発明が解決しようとする問題点）
重水中の10B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10Bに吸収されることを利用した測
定器を開発するに当り、重水中には放射性不純物
があるが、この内24Na，56Mnからのγ線の一部
は重水と反応して中性子を生成する。この中性子
を特に光中性子と呼ぶが、この光中性子は10B濃
度測定において誤差要因となるので、この光中性
子の影響を除去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) Measurement using the fact that neutrons emitted from a neutron source are decelerated by heavy water and the decelerated neutrons are absorbed by 10 B for online measurement of 10 B concentration in heavy water. When developing the device, heavy water contains radioactive impurities, and some of the gamma rays from 24 Na and 56 Mn react with the heavy water to generate neutrons. These neutrons are specifically called photoneutrons, and since these photoneutrons cause errors in 10 B concentration measurements, we are trying to provide a method to eliminate the influence of these photoneutrons.
（発明による解決手段）
中性子線源を有する測定容器に第１の中性子計
測器と、低エネルギー中性子に対するフイルター
付きの第２の中性子計測器とを設け、低エネルギ
ー中性子に対するフイルター付の第２の中性子計
測器にて中性子線源からの中性子及び光中性子の
うち低エネルギー中性子を除いた中性子量と光中
性子量のみを計測し、該計測値から予め計測され
ている中性子線源からの中性子量を差引くことに
より光中性子量を計算し、測定された中性子量か
ら10B濃度への変換に当り、光中性子の影響を除
去しうるようにした。(Solution by the Invention) A first neutron measuring instrument and a second neutron measuring instrument with a filter for low energy neutrons are provided in a measurement container having a neutron beam source, and the second neutron measuring instrument with a filter for low energy neutrons is provided. A measuring instrument measures only the amount of neutrons and photoneutrons excluding low-energy neutrons from the neutron source and the amount of neutrons from the neutron source that has been measured in advance is calculated from the measured values. By subtracting the amount of photoneutrons, we calculated the amount of photoneutrons, and when converting the measured neutron amount to 10 B concentration, we were able to remove the influence of photoneutrons.
（実施例）
第１図を参照してほう酸濃度測定器における測
定容器１内における中性子の態様について説明す
る。(Example) With reference to FIG. 1, the mode of neutrons in the measurement container 1 in the boric acid concentration measuring instrument will be described.
中性子線源５の252Cfから中性子が放射される。
これら中性子は、測定容器１内の重水Ｄによつて
減速された中性子と減速されない中性子とが混在
している。又重水Ｄで減速された中性子のうちに
は、さらに重水中のほう酸10Bに吸収される中性
子nB（第３図の10Bの中性子に対する見掛けの断面
積と中性子エネルギーとの関係グラフで明らかな
ように、中性子のエネルギーが低いと10Bに吸収
され易い）がある。従つて、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Ｄ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Ｄで減速されて計測器
４に達する中性子nDの和（ｎ＋nD）となる。 Neutrons are emitted from 252 Cf of the neutron source 5.
These neutrons are a mixture of neutrons that have been decelerated by the heavy water D in the measurement container 1 and neutrons that have not been decelerated. Furthermore, among the neutrons decelerated by heavy water D, neutrons n B are absorbed by boric acid 10 B in heavy water (as shown in the graph of the relationship between the apparent cross-sectional area and neutron energy for 10 B neutrons in Figure 3). When the energy of a neutron is low, it is easily absorbed by 10 B). Therefore, of the total amount of neutrons emitted from the neutron source 5, the amount measured by the measuring instrument 4 is the neutron n that reaches the measuring instrument 4 without being slowed down much by the heavy water D, and the neutrons n that are decelerated by the heavy water D and reach the measuring instrument. The sum of neutrons n D reaching 4 is (n+n D ).
一方、重水中には不純物である24Na，56Mnが
存在するが、これら24Naや56Mnから発生する高
エネルギーγ線の一部は重水Ｄと反応して光中性
子nPを発生する。 On the other hand, impurities such as 24 Na and 56 Mn are present in heavy water, and some of the high-energy γ rays generated from these 24 Na and 56 Mn react with heavy water D to generate photoneutrons nP .
したがつて計測器４では重水Ｄの減速された中
性子のうち10Bに吸収されなかつた中性子nD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＋nD＋nPが計測されることになる。 Therefore, in measuring instrument 4, 10 of the neutrons decelerated in heavy water D are neutrons n D that were not absorbed by B, and
3 of neutron n and photoneutron n P which are not slowed down much
Neutrons n+n D +n P of the species will be measured.
計測器４で計測される光中性子nPは252Cfから
の中性子でなく、発生源と異にしているので、計
測器４での測定値の誤差となる中性子である。し
たがつて252Cfからの中性子のみを計測するには
別途光中性子nPのみを計測し、この値を差引くこ
とにより、252Cfからのみの中性子量を計測できる
ことになる。 The photoneutrons n P measured by the measuring instrument 4 are not neutrons from 252 Cf, but are neutrons that cause an error in the measurement value by the measuring instrument 4 because the source is different. Therefore, to measure only the neutrons from 252 Cf, separately measure only the photoneutrons nP , and subtract this value, thereby making it possible to measure the amount of neutrons only from 252 Cf.
本発明はこの光中性子nPの計測のため、第２図
に示す如く、測定容器１に低エネルギー中性子に
対するフイルター例えばCdフイルタ６のついた
第２の中性子計測器４ａをもう一つ設ける。第４
図はCdの中性子に対する見掛けの断面積と中性
子エネルギーの関係グラフで、低エネルギーの中
性子がCdフイルタにより遮蔽され、高エネルギ
ーの光中性子と252Cfからの中性子のみが残り、
計測されることがわる。 In order to measure photoneutrons nP , the present invention provides another second neutron measuring instrument 4a equipped with a filter for low-energy neutrons, such as a Cd filter 6, in the measurement container 1, as shown in FIG. Fourth
The figure is a graph showing the relationship between the apparent cross-sectional area and neutron energy for Cd neutrons. Low-energy neutrons are blocked by the Cd filter, leaving only high-energy photoneutrons and neutrons from 252 Cf.
It is important to be measured.
再び第２図にもどり、重水Ｄで減速された中性
子nDはその時点では大半は低エネルギー化され、
第４図で明らかな如く、Cdフイルタ６に衝突し
て遮蔽吸収され、計測器４ａでは中性子量（ｎ＋
nD）のうち252Cfから直接照射されて計測器４ａ
に達する中性子ｎと光中性子nPのみ（ｎ＋nP）を
検出することになる。 Returning to Figure 2 again, most of the neutrons n D decelerated by heavy water D have low energy at that point,
As is clear from FIG. 4, the amount of neutrons (n+
n D ), 252 of which were directly irradiated from Cf and measuring instrument 4a
Only the neutrons n and photoneutrons n P (n+n P ) that reach this amount will be detected.
一方252Cfからの中性子量ｎは重水炉運転しな
い状態では56Mnや24Naが存在しないので、別途
あらかじめ計測しておくことができる。この量は
ｎであるから、したがつて（ｎ＋nP）−ｎ＝nPと
なり、光中性子量を計測することができる。 On the other hand, the neutron mass n from 252 Cf can be measured separately in advance since 56 Mn and 24 Na do not exist when the heavy water reactor is not operating. Since this amount is n, therefore (n+n P )-n=n P , and the amount of photoneutrons can be measured.
かくして計測器４で計測された光中性子量か
ら、10B濃度への変換に当り、光中性子の影響を
除去することができる。 In this way, the influence of photoneutrons can be removed when converting the amount of photoneutrons measured by the measuring device 4 into the 10 B concentration.
（効果）
測定器に低エネルギー中性子に対するフイルタ
ーを付けた計測器を別に設けたので、これにより
光中性子量を測定できるようになつた。この結果
測定された中性子量から10B濃度への変換に当り
光中性子の影響を除去できるようになつた。(Effects) We installed a separate measuring device with a filter for low-energy neutrons, which made it possible to measure the amount of photoneutrons. As a result, it became possible to remove the influence of photoneutrons when converting the measured neutron amount to 10 B concentration.
因みに第５図はCdフイルタ付の計数管を使用
して光中性子の影響を補正した場合と補正しない
場合を示し、光中性子の補正を行なわない場合に
は10B濃度は実際の値より約1PPm程低い値を示
し、正確な測定はできない。 Incidentally, Figure 5 shows the case where the influence of photoneutrons is corrected using a counter tube with a Cd filter and the case where it is not corrected.If the influence of photoneutrons is not corrected, the 10 B concentration is approximately 1PPm lower than the actual value. The value is so low that accurate measurements cannot be made.
第５図中●印は高周波プラズマ発光分析による
分析値を示し、ほう酸濃度測定器による測定値と
完全に一致していることがわかる。 In FIG. 5, the ● marks indicate the values analyzed by high-frequency plasma emission spectrometry, and it can be seen that they completely agree with the values measured by the boric acid concentration meter.
第１図はほう酸濃度測定器を示す。第２図はほ
う酸濃度測定器に付加するフイルタ付中性子計測
器を示す。第３図は10Bの中性子に対する見掛け
の断面積と中性子エネルギーとの関係を示すグラ
フ。第４図はCdの中性子に対する見かけの断面
積と中性子エネルギーとの関係を示すグラフ。第
５図は光中性子の補正をした場合としない場合の
10B濃度の測定結果を示すグラフ。第６図は従来
型ほう酸濃度測定器。
図において、ｎ……中性子源からあまり減速さ
れずに計測器に入る中性子、nP……光中性子、nD
……低エネルギー中性子、nB……10Bで吸１され
る中性子、１……測定容器、２……反射兼遮蔽
体、３……重水入口、４……（第１の）中性子計
測器、４ａ……低エネルギー中性子に対するフイ
ルタのついた第２の中性子計測器、５……中性子
線源、６……（低エネルギー中性子に対する）フ
イルタ。
Figure 1 shows a boric acid concentration measuring device. Figure 2 shows a neutron measuring device with a filter attached to the boric acid concentration measuring device. Figure 3 is a graph showing the relationship between the apparent cross section and neutron energy for 10 B neutrons. Figure 4 is a graph showing the relationship between the apparent cross section of Cd for neutrons and neutron energy. Figure 5 shows the results with and without photoneutron correction.
10 Graph showing the measurement results of B concentration. Figure 6 shows a conventional boric acid concentration measuring device. In the figure, n...neutrons that enter the measuring instrument without much deceleration from the neutron source, n P ...photoneutrons, n D
...low-energy neutron, n B ... neutron absorbed by 10 B, 1 ... measurement container, 2 ... reflection and shielding body, 3 ... heavy water inlet, 4 ... (first) neutron measuring instrument , 4a... Second neutron measuring instrument with a filter for low energy neutrons, 5... Neutron source, 6... Filter (for low energy neutrons).
Claims (1)
計測器４と低エネルギー中性子に対するフイルタ
ー付きの第２の中性子計測器４ａとを設け、低エ
ネルギー中性子に対するフイルター付の中性子計
測器４ａにて中性子線源からの中性子及び光中性
子のうち低エネルギー中性子を除いた中性子量と
光中性子量のみを計測し、該計測値から予め計測
されている中性子線源からの中性子量を差引くこ
とにより光中性子量を計算し、第１の中性子計測
器で測定された中性子量から10B濃度への変換に
当り、光中性子の影響を除去しうるようにしたこ
とを特徴とする重水炉におけるほう酸濃度測定器
の光中性子の影響除去方法。 ２ 低エネルギー中性子に対するフイルターを
Cdフイルターにしたことを特徴とする特許請求
の範囲第１項記載の重水炉におけるほう酸濃度測
定器の光中性子の影響除去方法。 ３ フイルターを10B含有プラスチツクフイルタ
ーとしたことを特徴とする特許請求の範囲第１項
記載の重水炉におけるほう酸濃度測定器の光中性
子の影響除去方法。[Claims] 1. A first neutron measuring device 4 and a second neutron measuring device 4a with a filter for low-energy neutrons are provided in a measurement container having a neutron source, and neutron measurement with a filter for low-energy neutrons is performed. Measure only the amount of neutrons and photoneutrons excluding low-energy neutrons among neutrons and photoneutrons from the neutron source in instrument 4a, and calculate the difference between the pre-measured neutron amount from the neutron source from the measured values. A heavy water reactor characterized in that the amount of photoneutrons is calculated by subtracting the amount of photoneutrons, and the influence of photoneutrons can be removed when converting the amount of neutrons measured by the first neutron measuring instrument into 10 B concentration. Method for removing the influence of photoneutrons on boric acid concentration measuring instruments. 2 Filter for low energy neutrons
A method for removing the influence of photoneutrons on a boric acid concentration measuring device in a heavy water reactor as claimed in claim 1, characterized in that the Cd filter is used. 3. A method for removing the influence of photoneutrons on a boric acid concentration measuring device in a heavy water reactor as claimed in claim 1, characterized in that the filter is a 10 B-containing plastic filter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62248111A JPS6491092A (en) | 1987-10-02 | 1987-10-02 | Removal of effect of photoneutron on boric acid concentration measuring apparatus for heavy water reactor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62248111A JPS6491092A (en) | 1987-10-02 | 1987-10-02 | Removal of effect of photoneutron on boric acid concentration measuring apparatus for heavy water reactor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6491092A JPS6491092A (en) | 1989-04-10 |
| JPH0555838B2 true JPH0555838B2 (en) | 1993-08-18 |
Family
ID=17173393
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62248111A Granted JPS6491092A (en) | 1987-10-02 | 1987-10-02 | Removal of effect of photoneutron on boric acid concentration measuring apparatus for heavy water reactor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6491092A (en) |
-
1987
- 1987-10-02 JP JP62248111A patent/JPS6491092A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6491092A (en) | 1989-04-10 |
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