JPH0560888A - Nuclear fuel rod - Google Patents
Nuclear fuel rodInfo
- Publication number
- JPH0560888A JPH0560888A JP3225615A JP22561591A JPH0560888A JP H0560888 A JPH0560888 A JP H0560888A JP 3225615 A JP3225615 A JP 3225615A JP 22561591 A JP22561591 A JP 22561591A JP H0560888 A JPH0560888 A JP H0560888A
- Authority
- JP
- Japan
- Prior art keywords
- nuclear fuel
- substance
- fuel rod
- permanent magnet
- core
- 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
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
【０００１】[0001]
【産業上の利用分野】本発明は、原子炉に装荷される核
燃料棒の安全性を高める構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for enhancing the safety of nuclear fuel rods loaded in a nuclear reactor.
【０００２】[0002]
【従来の技術】全発電量の中で、原子力発電が占める割
合が増えている今日、原子力発電の安全性を高めること
は重要な課題となっている。この課題を解決する方法は
いくつか提案されている。その一つとして重力を利用し
た構造の原子炉がある。例えば、加圧水型原子炉や高速
増殖炉では、原子炉に異常が発生した場合、制御棒を重
力を用いて原子炉の炉心内に落下させ負の反応度を与え
る構造になっている。また、高速増殖炉でも、炉心の上
方に中性子を吸収しやすい物質を永久磁石により支持
し、炉心が高温になり磁石のキュリー温度をこえると、
中性子を吸収しやすい物質を炉心内に落下させ、負の反
応度を与える構造になっているものもある。このよう
に、炉心の外から内側へ中性子を吸収しやすい物質を挿
入する構造になっている。例えば、炉心内にある核燃料
棒では、図２に示すように、中性子を吸収しやすい物質
は装荷されていない。なお、図２において、１は被覆
管、２はプレナムコイルばね、３は上部端栓、４は燃料
ペレットである。2. Description of the Related Art With the increasing proportion of nuclear power generation in the total amount of power generation, increasing the safety of nuclear power generation is an important issue. Several methods have been proposed to solve this problem. One of them is a nuclear reactor with a structure that utilizes gravity. For example, in a pressurized water reactor or a fast breeder reactor, when an abnormality occurs in the reactor, the control rod is dropped into the core of the reactor by using gravity to give a negative reactivity. Also in a fast breeder reactor, a material that easily absorbs neutrons is supported above the core by a permanent magnet, and when the core becomes hot and the Curie temperature of the magnet is exceeded,
There is also a structure in which a substance that easily absorbs neutrons is dropped into the core to give a negative reactivity. In this way, the structure is such that a substance that easily absorbs neutrons is inserted from the outside to the inside of the core. For example, a nuclear fuel rod in the core is not loaded with a substance that easily absorbs neutrons, as shown in FIG. In FIG. 2, 1 is a cladding tube, 2 is a plenum coil spring, 3 is an upper end plug, and 4 is a fuel pellet.
【０００３】この構造の原子炉では重力という自然の力
を用いており、電源喪失に伴う誤動作等による安全性の
低下を低減することができる。In the nuclear reactor of this structure, a natural force called gravity is used, and it is possible to reduce a decrease in safety due to a malfunction due to a power loss.
【０００４】[0004]
【発明が解決しようとする課題】上記従来技術では、炉
心の外側に中性子吸収物質を配置する構造になってお
り、核燃料棒のガスプレナム部の空間が有効に利用され
ていないという問題があった。本発明の目的は、上記ガ
スプレナム部の空間を有効に利用し、原子炉の安全性を
さらに高めることにある。The above prior art has a structure in which the neutron absorbing material is arranged outside the core, and there is a problem that the space of the gas plenum portion of the nuclear fuel rod is not effectively used. An object of the present invention is to effectively use the space of the gas plenum portion and further enhance the safety of the nuclear reactor.
【０００５】[0005]
【課題を解決するための手段】上記目的は、ガスプレナ
ム部の空間に中性子を吸収する物質およびそれを支持す
る永久磁石を配置することにより達成される。The above object is achieved by disposing a neutron-absorbing substance and a permanent magnet supporting it in the space of the gas plenum.
【０００６】[0006]
【作用】中性子を吸収する物質は、その周辺を磁性体で
取り囲み永久磁石により支持する。原子炉事故時、正の
反応度が加わり、炉心温度が上昇した場合、永久磁石も
温度上昇し、キュリー点を超えると永久磁石は磁力を失
い、中性子を吸収する物質は燃料ペレットの方へ落下す
る。それによって、炉心内に負の反応度を与えることが
できるようになり、炉心の温度上昇を緩和することがで
きるようになる。[Function] A substance absorbing neutrons is surrounded by a magnetic material and supported by a permanent magnet. When the reactor core temperature rises due to the addition of positive reactivity during a nuclear reactor accident, the temperature of the permanent magnet also rises, and when it exceeds the Curie point, the permanent magnet loses its magnetic force and the substance that absorbs neutrons falls toward the fuel pellets. To do. As a result, it becomes possible to give a negative reactivity to the core, and to moderate the temperature rise of the core.
【０００７】[0007]
【実施例】以下、本発明の一実施例を図面により説明す
る。図１において、１は被覆管、２はプレナムコイルば
ね、３は上部端栓、４は燃料棒ペレット、５は円筒状の
筒、６は永久磁石、７はＢ4Ｃ を磁性を持つ鉄で被覆し
た中性子を吸収しやすい物質（以下鉄被覆Ｂ4Ｃ と略記
する）である。このような構造にすることの利点を述べ
る。原子炉に正の反応度が添加されると炉心の温度が上
昇する。この温度上昇が起こると、原子炉は負の反応度
を与えるように制御される。しかし、なんらかの事象に
より炉心の温度が上昇し続けると、炉心を溶融する可能
性がある。本発明では、炉心の温度が上昇し、永久磁石
６の温度がキュリー点を超えると永久磁石は強磁性体か
ら常磁性体へ磁気転移を起こす。その結果、鉄被覆Ｂ4
Ｃ７ は自重により落下し、炉心に負の反応度を与え
る。これの原理を図３を用いて説明する。図３におい
て、８は鉄被覆Ｂ4Ｃ７ が落下した後の核燃料棒の出力
分布、９は鉄被覆Ｂ4Ｃ７ が落下する前の核燃料棒の出
力分布である。図３に示したように、中性子が鉄被覆Ｂ
4Ｃ７ に吸収され、図３のようにひずむ。このひずみの
効果は、結果として負の反応度を炉心に与えることにな
る。また、図１において、円筒状の筒５は、鉄被覆Ｂ4
Ｃ７ が落下するとき、プレナムコイルばねにひっかか
ることを防止するために設置する。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a cladding tube, 2 is a plenum coil spring, 3 is an upper end plug, 4 is a fuel rod pellet, 5 is a cylindrical tube, 6 is a permanent magnet, and 7 is B 4 C magnetic iron. It is a substance that easily absorbs coated neutrons (hereinafter abbreviated as iron-coated B 4 C). The advantages of such a structure will be described. The temperature of the core rises when a positive reactivity is added to the reactor. When this temperature rise occurs, the reactor is controlled to give a negative reactivity. However, if the temperature of the core continues to rise due to some event, the core may be melted. In the present invention, when the temperature of the core rises and the temperature of the permanent magnet 6 exceeds the Curie point, the permanent magnet causes a magnetic transition from a ferromagnetic material to a paramagnetic material. As a result, iron coating B 4
C7 falls by its own weight and gives a negative reactivity to the core. The principle of this will be described with reference to FIG. 3, 8 power distribution of a nuclear fuel rod after the iron coating B 4 C7 has been dropped 9 is a power distribution of a nuclear fuel rod prior to the iron coated B 4 C7 falls. As shown in FIG. 3, neutrons are iron-coated B
It is absorbed by 4 C7 and distorted as shown in Fig. 3. The effect of this strain results in a negative reactivity of the core. Further, in FIG. 1, the cylindrical tube 5 is an iron coating B 4
Install to prevent C7 from catching on the plenum coil spring when it falls.
【０００８】図４に鉄被覆Ｂ4Ｃ７ の構造の一例を示
す。図４において、１０は鉄の被覆、１１はヘリウムガ
ス溜め、１２はＢ4Ｃ ペレットである。Ｂ4Ｃ は（ｎ，
α）反応によりヘリウムガスを放出する。そのため、こ
のヘリウムガスによる鉄の被覆１０の内圧の増加により
鉄の被覆１０が破損しないように、ヘリウムガス溜め１
１を設けている。図５は、鉄被覆Ｂ4Ｃ７ の他の例であ
る。図５において、１３は中空Ｂ4Ｃ ペレットである。
図４に示した鉄被覆Ｂ4Ｃ７と同様、ヘリウムガス溜め
１１を設けているが、中空Ｂ4Ｃ ペレット１３を用いた
点が異なっている。また、図４，図５には、中性子を吸
収しやすい物質として、Ｂ4Ｃ を用いたが、ヘリウムガ
スを放出しやすいという問題もある。そのため、このヘ
リウムガスの放出が問題となる環境に本発明の核燃料棒
を設置する場合には、Ｂ4Ｃ の代わりに中性子を吸収し
やすい、ハフニウム，ユーロピウム，銀，インジウム，
カドミウム，サマリウムのうち、少なくとも一種類を含
む物質で構成しても同様の効果が得られる。これらの物
質を用いると、ヘリウムガス溜めが不要となる。発電用
原子炉で装荷される燃料集合体は、一般に、複数の核燃
料棒を一本以上用いて構成される。本発明の核燃料棒を
一本以上用いて構成された燃料集合体に対しても、本発
明と同様の効果がある。FIG. 4 shows an example of the structure of iron-coated B 4 C7. In FIG. 4, 10 is an iron coating, 11 is a helium gas reservoir, and 12 is a B 4 C pellet. B 4 C is (n,
α) Release helium gas by reaction. Therefore, in order to prevent the iron coating 10 from being damaged by the increase in the internal pressure of the iron coating 10 due to the helium gas, the helium gas reservoir 1
1 is provided. FIG. 5 is another example of the iron-coated B 4 C7. In FIG. 5, 13 is a hollow B 4 C pellet.
Similar to the iron-coated B 4 C 7 shown in FIG. 4, a helium gas reservoir 11 is provided, except that a hollow B 4 C pellet 13 is used. Further, in FIGS. 4 and 5, B 4 C is used as a substance that easily absorbs neutrons, but there is a problem that helium gas is easily released. Therefore, when the nuclear fuel rod of the present invention is installed in an environment where the release of helium gas is a problem, hafnium, europium, silver, indium, which easily absorbs neutrons instead of B 4 C, is used.
The same effect can be obtained by using a substance containing at least one of cadmium and samarium. The use of these materials eliminates the need for a helium gas reservoir. A fuel assembly loaded in a nuclear reactor for power generation is generally composed of one or more nuclear fuel rods. The same effect as that of the present invention can be obtained also from a fuel assembly constituted by using one or more nuclear fuel rods of the present invention.
【０００９】なお、炉心上部に中性子を吸収しやすい物
質を設置するため、炉心の上方から漏れる中性子を遮蔽
できるという効果もある。Since a substance that easily absorbs neutrons is installed in the upper part of the core, there is an effect that neutrons leaking from above the core can be shielded.
【００１０】[0010]
【発明の効果】本発明によれば、原子炉炉心に正の反応
度が過大に投入され、炉心の温度が上昇した場合に、負
の反応度を与えることができるので、原子炉の安全性を
よりいっそう高めることができる。According to the present invention, when the positive reactivity is excessively injected into the reactor core and the temperature of the core rises, the negative reactivity can be given, so that the safety of the reactor is improved. Can be further enhanced.
【図１】本発明の一実施例の核燃料棒の断面図。FIG. 1 is a sectional view of a nuclear fuel rod according to an embodiment of the present invention.
【図２】従来の核燃料棒の断面図。FIG. 2 is a sectional view of a conventional nuclear fuel rod.
【図３】核燃料棒の出力分布図。FIG. 3 is an output distribution map of nuclear fuel rods.
【図４】鉄被覆Ｂ4Ｃ の一実施例の断面図。FIG. 4 is a sectional view of an example of iron-coated B 4 C.
【図５】鉄被覆Ｂ4Ｃ の一実施例の断面図。FIG. 5 is a sectional view of an example of iron-coated B 4 C.
１…被覆管、２…プレナムコイルばね、３…上部端栓、
４…燃料棒ペレット、５…円筒状の筒、６…永久磁石、
７…Ｂ4Ｃ を磁性を持つ鉄で被覆した中性子を吸収しや
すい物質。1 ... cladding tube, 2 ... plenum coil spring, 3 ... upper end plug,
4 ... Fuel rod pellet, 5 ... Cylindrical tube, 6 ... Permanent magnet,
7 ... A substance that absorbs neutrons by coating B 4 C with magnetic iron.
Claims (8)
る被覆管、前記燃料ペレットから放出される核***性ガ
スを蓄えるガスプレナムおよびプレナムコイルばねから
なる核燃料棒において、前記ガスプレナム部内に中性子
を吸収しやすい物質及び永久磁石を備えたことを特徴と
する核燃料棒。1. A nuclear fuel rod comprising a fuel pellet, a cladding tube for containing the fuel pellet, a gas plenum for storing a fissionable gas released from the fuel pellet, and a plenum coil spring, and a substance that easily absorbs neutrons in the gas plenum portion. And a nuclear fuel rod having a permanent magnet.
すい物質は周辺を磁性体で囲まれた構造をもつ核燃料
棒。2. The nuclear fuel rod according to claim 1, wherein the substance that easily absorbs neutrons has a structure in which the periphery is surrounded by a magnetic material.
すい物質は中空構造である核燃料棒。3. The nuclear fuel rod according to claim 1, wherein the substance that easily absorbs neutrons has a hollow structure.
すい物質は、炭化ホウ素，ハフニウム，ユーロピウム，
銀，インジウム，カドミウム，サマリウムのうち少なく
とも一種類以上の物質で構成される核燃料棒。4. The substance according to claim 1, wherein the substance that easily absorbs neutrons is boron carbide, hafnium, europium,
A nuclear fuel rod composed of at least one substance selected from silver, indium, cadmium, and samarium.
すい物質は前記永久磁石よりも前記燃料ペレットに近い
位置に配置された核燃料棒。5. The nuclear fuel rod according to claim 1, wherein the substance that easily absorbs neutrons is located closer to the fuel pellet than the permanent magnet.
ねの内側に筒状の物質を備えた核燃料棒。6. The nuclear fuel rod according to claim 1, wherein a cylindrical material is provided inside the plenum coil spring.
て、前記核燃料棒を少なくとも一本装荷した燃料集合
体。7. A fuel assembly according to claim 1, 2, 3, 4, 5 or 6, wherein at least one nuclear fuel rod is loaded.
原子炉の炉心。8. A reactor core in which the fuel assemblies according to claim 7 are integrally loaded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3225615A JPH0560888A (en) | 1991-09-05 | 1991-09-05 | Nuclear fuel rod |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3225615A JPH0560888A (en) | 1991-09-05 | 1991-09-05 | Nuclear fuel rod |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0560888A true JPH0560888A (en) | 1993-03-12 |
Family
ID=16832097
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3225615A Pending JPH0560888A (en) | 1991-09-05 | 1991-09-05 | Nuclear fuel rod |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0560888A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2709858A1 (en) * | 1993-09-08 | 1995-03-17 | Toshiba Kk | Fast neutron reactor core with gas-sealed assemblies |
| RU2482556C2 (en) * | 2010-06-25 | 2013-05-20 | Прэтт & Уитни Рокетдайн, Инк. | Nuclear fuel composition, nuclear reactor, method of producing nuclear fuel composition (versions) and method of imparting subcriticality to nuclear fuel |
-
1991
- 1991-09-05 JP JP3225615A patent/JPH0560888A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2709858A1 (en) * | 1993-09-08 | 1995-03-17 | Toshiba Kk | Fast neutron reactor core with gas-sealed assemblies |
| RU2482556C2 (en) * | 2010-06-25 | 2013-05-20 | Прэтт & Уитни Рокетдайн, Инк. | Nuclear fuel composition, nuclear reactor, method of producing nuclear fuel composition (versions) and method of imparting subcriticality to nuclear fuel |
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