JPH05196771A - Hollow core of fast reactor - Google Patents
Hollow core of fast reactorInfo
- Publication number
- JPH05196771A JPH05196771A JP4027353A JP2735392A JPH05196771A JP H05196771 A JPH05196771 A JP H05196771A JP 4027353 A JP4027353 A JP 4027353A JP 2735392 A JP2735392 A JP 2735392A JP H05196771 A JPH05196771 A JP H05196771A
- Authority
- JP
- Japan
- Prior art keywords
- core
- hollow
- fast reactor
- annular shape
- substance
- 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.)
- Granted
Links
- 239000000446 fuel Substances 0.000 claims abstract description 25
- 239000011800 void material Substances 0.000 claims abstract description 23
- 239000000126 substance Substances 0.000 claims abstract description 21
- 239000002826 coolant Substances 0.000 claims abstract description 19
- 230000000712 assembly Effects 0.000 claims abstract description 15
- 238000000429 assembly Methods 0.000 claims abstract description 15
- 239000006096 absorbing agent Substances 0.000 claims abstract description 13
- 230000002159 abnormal effect Effects 0.000 claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims description 11
- 239000000155 melt Substances 0.000 claims description 3
- 230000009257 reactivity Effects 0.000 abstract description 35
- 230000007246 mechanism Effects 0.000 abstract description 12
- 238000002844 melting Methods 0.000 abstract description 5
- 230000008018 melting Effects 0.000 abstract description 5
- 238000010276 construction Methods 0.000 abstract 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 19
- 229910052708 sodium Inorganic materials 0.000 description 19
- 239000011734 sodium Substances 0.000 description 19
- 238000009826 distribution Methods 0.000 description 14
- 230000004907 flux Effects 0.000 description 13
- 238000010521 absorption reaction Methods 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- 238000001228 spectrum Methods 0.000 description 6
- 238000009835 boiling Methods 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 229910052782 aluminium Inorganic materials 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000004992 fission Effects 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 102200052313 rs9282831 Human genes 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C1/00—Reactor types
- G21C1/02—Fast fission reactors, i.e. reactors not using a moderator ; Metal cooled reactors; Fast breeders
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21C—NUCLEAR REACTORS
- G21C9/00—Emergency protection arrangements structurally associated with the reactor, e.g. safety valves provided with pressure equalisation devices
- G21C9/02—Means for effecting very rapid reduction of the reactivity factor under fault conditions, e.g. reactor fuse; Control elements having arrangements activated in an emergency
-
- 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
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Structure Of Emergency Protection For Nuclear Reactors (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、中央部分が空洞部とな
るように多数の燃料集合体を束ね全体として円環状に配
列することにより、ナトリウムボイド反応度を小さく抑
え、ＡＴＷＳ（異常な過渡変化時のスクラム失敗）等の
事象に対しても固有の潜在的安全性を有する高速炉の中
空炉心に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the sodium void reactivity to a small level and suppresses ATWS (abnormal transient) by bundling a large number of fuel assemblies so that the central part becomes a hollow part and arranging them in an annular shape as a whole. The present invention relates to a hollow core of a fast reactor, which has inherent potential safety against events such as scrum failure at the time of change).
【０００２】[0002]
【従来の技術】原子炉の炉心形状は、中性子経済から球
形又はそれに近い円柱形が望ましいとされ、炉心体積に
対する表面積の比を最小にして炉心外への中性子の漏洩
を制限している。高速炉の炉心は、一般的には六角柱状
の燃料集合体を多数本束ねた構成であり、それを包絡し
た形状は従来ほぼ円柱状である。From the viewpoint of neutron economy, it is desirable that the core shape of a nuclear reactor is spherical or cylindrical, and the ratio of surface area to core volume is minimized to limit leakage of neutrons out of the core. The core of a fast reactor is generally configured by bundling a large number of hexagonal columnar fuel assemblies, and the enveloped form of the fuel assemblies is generally cylindrical.
【０００３】図８は従来の小型炉心の例であり、Ａは縦
断面図、Ｂは横断面図である。炉心１０の高さ２ｈa と
直径２ａは同程度に設定されている。この炉心の中性子
束分布は図９Ａ，Ｂに示すように釣鐘状となり、径方向
の中性子漏洩ＮR と軸方向の中性子漏洩ＮA は同程度と
なっている。FIG. 8 shows an example of a conventional small core, where A is a longitudinal sectional view and B is a transverse sectional view. Height 2h a and the diameter 2a of the core 10 is set to the same extent. The neutron flux distribution of this core has a bell shape as shown in FIGS. 9A and 9B, and the radial neutron leakage N R and the axial neutron leakage N A are approximately the same.
【０００４】炉心の大型化に伴って炉心高さと炉心直径
は増加するが、冷却材出口温度の上昇に伴う燃料被覆管
の許容温度制限などから、炉心高さはある程度以上には
できない。また高速炉の冷却材ナトリウムの沸騰防止の
観点からも炉心高さは制限される。具体的には、炉心高
さは１〜１．２ｍ程度が限界とされている。従って図１
０に示すように、高速炉の炉心１２は偏平な円柱形状と
なる。Ａは縦断面図、Ｂは横断面図である。Although the core height and the core diameter increase with the increase in size of the core, the core height cannot be increased above a certain level due to the allowable temperature limit of the fuel cladding tube accompanying the rise of the coolant outlet temperature. The core height is also limited from the viewpoint of preventing boiling of sodium coolant in a fast reactor. Specifically, the core height is limited to about 1 to 1.2 m. Therefore, FIG.
As shown in 0, the core 12 of the fast reactor has a flat cylindrical shape. A is a longitudinal sectional view and B is a lateral sectional view.
【０００５】一方、高速炉炉心の安全性に重要な役割を
果たしているナトリウムボイド反応度係数は、中央部で
の局所的ボイド反応度係数は一般に正で、周辺部では負
である。炉心の大型化と共にボイド反応度係数は増大
し、炉心全体としても、図１２に示すように負（小型炉
心）から正（中型炉心）になり、大型炉心ではその値が
更に増加していく。因に、ｐ点ではボイド反応度係数が
ゼロでこれ以下では冷却材が沸騰しても炉が暴走するこ
とはない。またｑ点ではボイド反応度係数が丁度β（遅
発中性子割合）に一致しており、これ以下では冷却材沸
騰が生じても即発臨界にはならず、炉の出力増加はさほ
ど急激ではない。ボイド反応度係数が例えβ値（１ド
ル）を超えても数ドル程度に抑えられれば出力増加の緩
和効果は大きい。On the other hand, the sodium void reactivity coefficient which plays an important role in the safety of the fast reactor core is generally positive in the local void reactivity coefficient in the central portion and negative in the peripheral portion. As the core becomes larger, the void reactivity coefficient increases, and as shown in Fig. 12, the void reactivity coefficient changes from negative (small core) to positive (medium core), and the value further increases in the large core. Incidentally, the void reactivity coefficient is zero at the point p, and below this, even if the coolant boils, the furnace does not run away. At point q, the void reactivity coefficient is exactly equal to β (delayed neutron rate). Below this, even if coolant boiling occurs, prompt criticality does not occur, and the reactor power output does not increase very rapidly. Even if the void reactivity coefficient exceeds the β value ($ 1), if it is suppressed to about several dollars, the effect of mitigating the increase in output is great.
【０００６】[0006]
【発明が解決しようとする課題】前記のように従来の高
速炉では、炉心の大型化に伴って偏平円柱状となる。そ
れによって図１１のＡに示すように、径方向の中性子束
分布は平坦化されて径方向の中性子漏洩は減少するもの
の、同図Ｂに示すように軸方向の中性子束分布は小型炉
心のように釣鐘状のままで軸方向の中性子漏洩は大き
く、中性子の漏洩の観点からは、径方向と軸方向でバラ
ンスが崩れている。このため軸方向にブランケットを部
分的に組み込む軸非均質炉が考えられているが、燃料の
製作が複雑になる欠点がある。As described above, the conventional fast reactor has a flat cylindrical shape as the core becomes larger. As a result, as shown in FIG. 11A, the neutron flux distribution in the radial direction is flattened and the neutron leakage in the radial direction is reduced, but as shown in FIG. 11B, the neutron flux distribution in the axial direction is similar to that of a small core. However, the neutron leakage in the axial direction is large with the shape of a bell, and the balance between the radial direction and the axial direction is unbalanced from the viewpoint of neutron leakage. For this reason, an axial non-homogeneous furnace in which a blanket is partially incorporated in the axial direction has been considered, but it has a drawback that fuel production becomes complicated.
【０００７】このように炉心の大型化と共にナトリウム
ボイド反応度係数が正となり、その値が大きくなってい
くため、冷却材流量低下や過出力などの事象において冷
却材ナトリウムが沸騰すると、炉心の発熱が急激に上昇
して、燃料溶融や炉心損傷を招く恐れがある。これを防
止するために、中性子検出器、温度計、流量計などを用
いた安全保護系を設け、設定値を超えた時に電気回路を
作動させて制御棒を炉心に挿入するようになっている
が、制御棒の挿入失敗の確率を完全に排除することはで
きない。このようなことから、単純で固有の安全性を有
するような大型高速炉の炉心構造の開発が求められてい
た。なお、従来の方式でボイド反応度係数を低減するた
めには、更に炉心高さを極端に低くして、より偏平にす
る必要がある。As the core becomes larger, the sodium void reactivity coefficient becomes positive and its value increases, so that when the coolant sodium boils in an event such as a decrease in coolant flow rate or overpower, the core heat is generated. May rise rapidly, causing fuel melting and core damage. In order to prevent this, a safety protection system using a neutron detector, thermometer, flow meter, etc. is installed, and when the set value is exceeded, the electric circuit is activated and the control rod is inserted into the core. However, the probability of control rod insertion failure cannot be completely eliminated. For these reasons, there has been a demand for the development of a core structure for a large fast reactor that is simple and has inherent safety. In order to reduce the void reactivity coefficient by the conventional method, it is necessary to further reduce the core height to be flatter.
【０００８】本発明の目的は、上記のような従来技術の
課題を解決し、簡単な構成で低ボイド反応度係数を持
ち、何らかの出力異常増大に対して反応度の自己緩和機
能を有し、安全性が高く経済的な高速炉の炉心配置を提
供することである。The object of the present invention is to solve the problems of the prior art as described above, to have a low void reactivity coefficient with a simple structure, and to have a self-relaxation function of the reactivity with respect to some abnormal output increase, It is to provide a core arrangement of a fast reactor which is safe and economical.
【０００９】[0009]
【課題を解決するための手段】本発明は、中央部分が空
洞部となるように、多数の燃料集合体を束ねて全体とし
て円環状に配置した構造の高速炉の中空炉心である。複
数本の制御棒は、円環状炉心の同一円周上に配列する。
その位置は、例えば、円環状炉心で径方向中性子束分布
がほぼ最大値をとるような同一円周上である。SUMMARY OF THE INVENTION The present invention is a hollow core of a fast reactor having a structure in which a large number of fuel assemblies are bundled and arranged in an annular shape so that a central portion becomes a hollow portion. The plurality of control rods are arranged on the same circumference of the annular core.
The position is, for example, on the same circumference where the radial neutron flux distribution takes a maximum value in the annular core.
【００１０】炉心空洞部などを利用して反応度自己緩和
機構を組み込む。反応度自己緩和機構としては、空洞部
内に冷却材と同等の核的特性を有し且つ冷却材の温度異
常上昇時に溶融する物質（例えばアルミニウムやアルミ
ニウム合金等）を設置する構成、空洞部の上方に中性子
吸収体を設置して出力異常上昇時に前記中性子吸収体を
空洞部に落下させる構成、あるいは空洞部に高エネルギ
ー中性子に対する反応断面積が大きい物質（例えば、12
Ｃや14Ｎを含有する物質）を設置する構成がある。また
これら高エネルギー中性子に対する反応断面積が大きい
物質を燃料に組み込むことも可能である。A reactivity self-relaxation mechanism is incorporated by utilizing a core cavity or the like. As the reactivity self-relaxation mechanism, a configuration is provided in which a substance (for example, aluminum or aluminum alloy) that has the same nuclear characteristics as the coolant and that melts when the coolant temperature rises abnormally is installed in the cavity, above the cavity. A neutron absorber is installed in the neutron absorber to drop the neutron absorber into the cavity when the output rises abnormally, or the cavity has a large reaction cross section for high-energy neutrons (for example, 12
There is a configuration in which a substance containing C or 14 N) is installed. It is also possible to incorporate a substance having a large reaction cross section for these high-energy neutrons into the fuel.
【００１１】[0011]
【作用】本発明では炉心の中央部分に空洞部が存在する
ため、該空洞部からの中性子漏洩によりボイド反応度係
数を中型炉心ないし小型炉心なみに小さく抑えることが
できる。ナトリウムボイド反応度への影響因子として
は、中性子スペクトルのハードニング、中性子漏洩
の増加、ナトリウムによる中性子吸収の低下、セル
フ・シールディングの変化、があるが、一般にとが
支配的である。は正に働き、は負に働き、両者の和
でボイド反応度が決まる。本発明では、中性子漏洩を適
度に設定することによってナトリウムボイド反応度係数
を低く抑えることになる。In the present invention, since the hollow portion exists in the central portion of the core, the void reactivity coefficient can be suppressed to a level as small as that of the medium-sized core or the small core due to the neutron leakage from the hollow portion. Factors influencing sodium void reactivity include neutron spectrum hardening, increased neutron leakage, decreased neutron absorption by sodium, and changes in self-shielding, but generally dominates. Works positively, works negatively, and the void reactivity is determined by the sum of both. In the present invention, the sodium void reactivity coefficient is suppressed to a low level by appropriately setting the neutron leakage.
【００１２】この中空炉心では径方向中性子束分布が円
環状分布になるため、制御棒は同一円周上のみに配列す
ればよく、小数本で効果的な配置が可能である。また炉
心空洞部は、反応度自己緩和機能を持たせるのに利用で
き、それによって大型炉心でも固有安全性が著しく高ま
る。In this hollow core, the radial direction neutron flux distribution has an annular distribution, so that the control rods need only be arranged on the same circumference, and a small number of control rods can be effectively arranged. The core cavity can also be used to provide a reactivity self-relaxation function, which significantly enhances intrinsic safety even in a large core.
【００１３】[0013]
【実施例】図１は本発明に係る高速炉の中空炉心の概念
図を示したものであり、Ａは縦断面図、Ｂは横断面図で
ある。これは従来の大型炉心の中央部分を中空化したよ
うな構造である。即ち炉心中央部分に空洞部１４（直径
２ｃ）を形成するように、多数の燃料集合体を束ねて全
体として円環状に配置して炉心１６（最外径２ｄ、高さ
２ｈc ）を構成している。このような中空炉心構造では
空洞部１４を通って一部の中性子は外部に漏洩する。そ
のため、あたかも小型炉心ないし中型炉心と同程度のナ
トリウムボイド反応度係数が得られる。軸方向の中性子
束分布は図２Ｂに示すような釣鐘状となるが、径方向の
中性子束分布は、図２Ａに示すようにほぼ平坦で、中央
部が中空化に伴いやや歪む程度である。また炉心全体の
発熱量は空洞部分の直径がさほど大きくなければ、従来
の中実炉心に比べてやや減少する程度に抑えられる。な
お図２Ｃは中性子束３次元分布概念図である。1 is a conceptual view of a hollow core of a fast reactor according to the present invention, in which A is a longitudinal sectional view and B is a transverse sectional view. This is a structure in which the central portion of a conventional large-scale core is hollow. That is, a large number of fuel assemblies are bundled and arranged in an annular shape as a whole to form a core 16 (outermost diameter 2d, height 2h c ) so as to form a cavity 14 (diameter 2c) in the central portion of the core. ing. In such a hollow core structure, some neutrons leak outside through the cavity 14. Therefore, it is possible to obtain the sodium void reactivity coefficient as high as that of the small-sized core or the medium-sized core. The neutron flux distribution in the axial direction has a bell shape as shown in FIG. 2B, but the neutron flux distribution in the radial direction is almost flat as shown in FIG. 2A, and the central portion is slightly distorted due to hollowing. Further, the calorific value of the entire core can be suppressed to a level that is slightly smaller than that of the conventional solid core unless the diameter of the hollow portion is so large. 2C is a conceptual diagram of three-dimensional neutron flux distribution.
【００１４】例えば、１００万ｋＷｅ級の大型高速炉の
代表的炉心設計では、従来の中実炉心構造の場合、炉心
高さが約１ｍ、外径は約３．３ｍであるが、中央部に直
径約１ｍの空洞部を設けても、同一炉心体積にするため
の炉心外径は約０．１５ｍの増加（半径では僅か０．０
７ｍの増加）でしかなく、炉心外径の増加に伴うコスト
増は僅かである。For example, in a typical core design of a large fast reactor of 1 million kWh class, in the case of a conventional solid core structure, the core height is about 1 m and the outer diameter is about 3.3 m, Even if a cavity with a diameter of about 1 m is provided, the core outer diameter for achieving the same core volume increases by about 0.15 m (radius only 0.0
However, the increase in cost due to the increase in the core outer diameter is slight.
【００１５】従来の炉心配置では多数本の制御棒を炉心
に分散させる必要があったが、本発明に係る中空炉心で
は、図２Ｃに示すように中性子束分布が円環状になるた
め、制御棒は同一円周上（図１Ｂの破線１８で示す）の
みに配列すればよいことになる。換言すると図２Ａに示
すように、制御棒２０を径方向中性子束分布がほぼ最大
値をとる位置に配列すればよい。そのため少数本の制御
棒による効果的な配置が可能となる。In the conventional core arrangement, it was necessary to disperse a large number of control rods in the core, but in the hollow core according to the present invention, the neutron flux distribution becomes annular as shown in FIG. Need only be arranged on the same circumference (shown by the broken line 18 in FIG. 1B). In other words, as shown in FIG. 2A, the control rods 20 may be arranged at positions where the radial neutron flux distribution has a maximum value. Therefore, it is possible to effectively arrange with a small number of control rods.
【００１６】図３は本発明に係る中空炉心を設置した高
速炉の一例を示している。原子炉容器３０の内部に中空
炉心３２が位置し、ドーナッツ状の炉心支持構造３４に
より支持される。炉心支持構造３４の下方には中央が高
く周囲が低くなるように円環状に凹陥したコアキャッチ
ャ３６を設ける。原子炉容器３０の上端開口には遮蔽プ
ラグ３８を被せる。原子炉容器３０の内部は冷却材であ
る液体ナトリウムが流通する。中空炉心３２の下方の下
部プレナム４０には低温ナトリウムがあり、中空炉心３
２の上方の上部プレナム４２には高温ナトリウムがあ
る。液体ナトリウムの上部はカバーガス４４で覆われ
る。炉心空洞部４６の上方には中性子吸収体４８が位置
している。中性子吸収体４８は、事故時に、重力落下し
て原子炉の反応度を負にして原子炉を安全に停止させる
機能を果たす。その詳細は後述する。これにも中空炉心
構造は効果的である。また炉心支持機構３４及びコアキ
ャッチャ３６によって、万一の炉心損傷事故に対しても
再臨界事故に至らないように、溶融燃料を円環状に分散
させることができ、固有の安全性を保ち易い。これも中
空炉心の長所である。FIG. 3 shows an example of a fast reactor equipped with a hollow core according to the present invention. A hollow core 32 is located inside the reactor vessel 30, and is supported by a donut-shaped core support structure 34. Below the core support structure 34 is provided a core catcher 36 which is recessed in an annular shape so that the center is high and the periphery is low. A shield plug 38 is put on the upper end opening of the reactor vessel 30. Liquid sodium that is a coolant flows through the inside of the reactor vessel 30. There is low temperature sodium in the lower plenum 40 below the hollow core 32.
There is hot sodium in the upper plenum 42 above 2. The upper part of the liquid sodium is covered with the cover gas 44. A neutron absorber 48 is located above the core cavity 46. In the event of an accident, the neutron absorber 48 has a function of dropping by gravity to make the reactivity of the reactor negative and stopping the reactor safely. The details will be described later. The hollow core structure is also effective for this. Further, by the core support mechanism 34 and the core catcher 36, the molten fuel can be dispersed in an annular shape so as to prevent a recriticality accident even in the event of a core damage accident, and it is easy to maintain the inherent safety. This is also an advantage of the hollow core.
【００１７】図４は高速炉の固有の安全機能を有する漏
洩中性子パスの形成例を示す。中空炉心３２の空洞部密
閉空間５０内に、冷却材と同等の核的特性を有し且つ冷
却材の温度異常上昇時に溶融する可溶融物質５２を設置
する。異常な過渡変化で且つ制御棒による炉停止が行え
ないような事象（ＡＴＷＳ）発生時には、冷却材の温度
異常上昇により可溶融物質５２が溶融して、下部空間５
４に落下し、その後はボイドになる。これにより中性子
が炉心から漏洩する割合が増加して負の反応度が入り、
高速炉は安全に停止する。上記の可溶融物質５２として
は、例えばアルミニウムがある。アルミニウムは核的特
性がナトリウムに極めて似通っており、その融点は６６
０℃である。また作動温度はアルミニウムを合金にする
などにより変えられる。FIG. 4 shows an example of forming a leaky neutron path having a safety function peculiar to a fast reactor. In the cavity closed space 50 of the hollow core 32, a fusible substance 52 having the same nuclear characteristics as the coolant and melting when the coolant temperature rises abnormally is installed. At the time of an abnormal transition (ATWS) in which the furnace cannot be stopped by the control rod, the meltable substance 52 is melted due to the abnormal temperature rise of the coolant, and the lower space 5
It drops to 4, then becomes a void. This increases the rate at which neutrons leak from the core and introduces negative reactivity,
The fast reactor shuts down safely. Examples of the fusible substance 52 include aluminum. Aluminum has very similar nuclear properties to sodium, and its melting point is 66.
It is 0 ° C. The operating temperature can be changed by alloying aluminum.
【００１８】図５は中性子吸収体を落下させる例であ
る。ここでは中性子吸収体として液体（例えば、ほう酸
水や液体リチウムなど）を用いている。中空炉心３２の
空洞部に受け容器５５を設け、その上方に中性子吸収体
５６を充填した上部容器５８を設ける。該上部容器５８
と受け容器５５との間は弁６０を備えた連結管６２で連
結する。弁６０は、事故時の温度異常上昇で受動的に開
く方式が望ましく、例えば形状記憶合金やキュリー点電
磁石によって作動する構造とする。このような構成は、
通常の制御棒の挿入による炉停止機構と原理的に異なる
ことから、多様化が図れ、炉停止機構の総合的信頼性が
向上する。また中性子吸収体としては固体（例えばＢ4
ＣやＺｒＨなど）を用いることも可能である。FIG. 5 shows an example of dropping the neutron absorber. Here, a liquid (for example, boric acid water or liquid lithium) is used as the neutron absorber. A receiving container 55 is provided in the hollow portion of the hollow core 32, and an upper container 58 filled with a neutron absorber 56 is provided above the receiving container 55. The upper container 58
The receiving container 55 and the receiving container 55 are connected by a connecting pipe 62 equipped with a valve 60. It is desirable that the valve 60 be passively opened when the temperature rises abnormally in the event of an accident. Such a configuration
Since it is different in principle from the normal reactor shutdown mechanism by inserting control rods, it is possible to diversify and improve the overall reliability of the reactor shutdown mechanism. The neutron absorber is a solid (for example, B 4
C, ZrH, etc.) can also be used.
【００１９】図６は中空炉心３２の空洞部に、高エネル
ギー中性子に対する反応断面積（但し核***反応は除
く）が大きい物質６４を設置する構成である。事故時に
冷却材温度が異常上昇し、炉心で冷却材ナトリウムの沸
騰が生じると、ナトリウムによる減速効果が減少し、中
性子のエネルギースペクトルは高エネルギー側にシフト
する。核***エネルギー領域で中性子吸収断面積が上昇
する物質６４を空洞部に設置しておくと、この物質６４
により高速炉の出力上昇は抑制され、この自己制御機能
により高速炉は安全を保つ。この種の物質としては、例
えば炭素がある。図７Ａに12Ｃの中性子吸収断面積σa
と高速炉の中性子エネルギースペクトルを示す。高速炉
の中性子エネルギーの平均値は１×１０5 〜２×１０5
eV程度であるであるが、12Ｃの中性子吸収断面積はほぼ
この近傍で最小値を取るので、ナトリウムボイドが生じ
て中性エネルギースペクトルが高エネルギー側にシフト
すると、12Ｃによる吸収効果で負の反応度が入り原子炉
出力上昇が緩和される。12Ｃに代えて14Ｎを用いること
も可能である。図７Ｂに示すように、14Ｎの中性子吸収
断面積σa は１０5 eV以上で特に増加していないが、そ
の代わりに（ｎ，ｐ）反応の断面積σp が急激に増加し
ており、連鎖反応に寄与する中性子が失われる点では吸
収の場合と同様である。図７では12Ｃと14Ｎの例を示し
たが、このような特性を有する適切な物質を選定すれ
ば、反応度自己制御機能を有する炉心が得られる。12Ｃ
と14Ｎは、例えばＳｉＣやＳｉ3 Ｎ4 などのセラミック
スの形態で炉心空洞部に設置すれば、高温環境下での使
用にも充分耐えうる。FIG. 6 shows a structure in which a substance 64 having a large reaction cross-sectional area for high-energy neutrons (excluding fission reaction) is installed in the hollow portion of the hollow core 32. When the coolant temperature rises abnormally at the time of the accident and boiling of the coolant sodium occurs in the core, the moderating effect of sodium decreases and the neutron energy spectrum shifts to the high energy side. If a substance 64 whose neutron absorption cross section increases in the fission energy region is installed in the cavity, this substance 64
This suppresses the output rise of the fast reactor, and this self-control function keeps the fast reactor safe. An example of this type of substance is carbon. In Fig. 7A, the neutron absorption cross section of 12 C σ a
And the neutron energy spectrum of the fast reactor is shown. Average value of neutron energy of fast reactor is 1 × 10 5 to 2 × 10 5
Although it is about eV, the neutron absorption cross section of 12 C takes the minimum value in the vicinity of this, so if sodium voids occur and the neutral energy spectrum shifts to the high energy side, the absorption effect due to 12 C will cause a negative effect. The reactivity of the reactor is increased and the increase in reactor power is moderated. It is also possible to use 14 N instead of 12 C. As shown in FIG. 7B, the neutron absorption cross section σ a of 14 N did not increase particularly at 10 5 eV or more, but instead, the cross section σ p of the (n, p) reaction increased sharply. , It is similar to the case of absorption in that the neutrons that contribute to the chain reaction are lost. Although FIG. 7 shows an example of 12 C and 14 N, a core having a reactivity self-controlling function can be obtained by selecting an appropriate substance having such characteristics. 12 C
If 14 N and 14 N are installed in the core cavity in the form of ceramics such as SiC and Si 3 N 4 , they can sufficiently withstand use in a high temperature environment.
【００２０】更に、円環状炉心を構成する多数の燃料集
合体のうち少なくとも一部に、高エネルギー中性子に対
する反応断面積が大きい物質を組み込んだ燃料（例えば
12Ｃや14Ｎを用いた炭化物や窒化物燃料）を用いること
もできる。そのような構成にすると、ボイド反応度低減
効果を更に高めることができる。Further, a fuel in which a substance having a large reaction cross-section for high-energy neutrons is incorporated into at least a part of a large number of fuel assemblies forming the annular core (for example,
Carbide or nitride fuel using 12 C or 14 N can also be used. With such a configuration, the void reactivity reduction effect can be further enhanced.
【００２１】[0021]
【発明の効果】本発明は上記のように、中央部分が空洞
部となるように多数の燃料集合体を束ねて全体として円
環状に配置することにより、中性子漏洩量を適度に高
め、大型炉心であっても小型炉心ないし中型炉心なみの
低ボイド反応度係数が得られるようになり、ナトリウム
沸騰事故等に対して、大型炉心でも固有安全性が高ま
る。また円環状炉心であるため、制御棒を同一円周上に
配列することが可能となり、制御棒及びその駆動機構の
数を削減でき、駆動機構の配置も容易となる。更に円環
状炉心の下方に、円環状に凹陥したコアキャッチャを設
置することで、万一の炉心損傷事故による溶融燃料が円
環状に分散し、再臨界事故を防止できる。As described above, according to the present invention, a large number of fuel assemblies are bundled so that the central portion thereof becomes a hollow portion and arranged in an annular shape as a whole, whereby the amount of neutron leakage is appropriately increased and a large core is provided. However, a low void reactivity coefficient similar to that of a small-sized core or a medium-sized core can be obtained, and the intrinsic safety of a large-sized core is improved against sodium boiling accidents. Further, because of the annular core, the control rods can be arranged on the same circumference, the number of control rods and their drive mechanisms can be reduced, and the drive mechanisms can be easily arranged. Further, by installing a core catcher recessed in an annular shape below the annular core, molten fuel due to an accident of core damage is dispersed in an annular shape and a recriticality accident can be prevented.
【００２２】本発明では、炉心空洞部を反応度自己緩和
機能を持たせるのに利用できる。空洞部を利用して、そ
の内部に冷却材と同等の核的特性を有し且つ冷却材の温
度異常上昇時に溶融する物質を設置することにより、溶
融した後はボイドになることから、空洞部からの中性子
漏洩が増加する。空洞部の上方に中性子吸収体を設置し
て出力異常上昇時に前記中性子吸収体が空洞部に落下す
るように構成すると、中性子吸収が増大する。あるいは
高エネルギー中性子に対する反応断面積が大きい物質を
設置すると、炉心でナトリウム沸騰事故が生じても中性
子エネルギースペクトルが高エネルギー側にシフトし
て、その物質との反応により連鎖反応にあずかる中性子
の数が減少する。これらによって反応度の自己緩和が出
来る安全な炉心を実現できる。In the present invention, the core cavity can be used to have the reactivity self-relaxation function. By using a cavity and installing a substance that has the same nuclear characteristics as the coolant and that melts when the temperature of the coolant rises abnormally, a void will appear after melting. Neutron leakage from the If a neutron absorber is installed above the cavity and the neutron absorber falls into the cavity when the output rises abnormally, the neutron absorption increases. Alternatively, if a substance with a large reaction cross section for high-energy neutrons is installed, the neutron energy spectrum will shift to the high-energy side even if a sodium boiling accident occurs in the core, and the number of neutrons participating in a chain reaction due to the reaction with that substance Decrease. These can realize a safe core that can self-relax the reactivity.
【図１】本発明に係る高速炉の中空炉心の概念図。FIG. 1 is a conceptual diagram of a hollow core of a fast reactor according to the present invention.
【図２】その中空炉心の中性子束分布の説明図。FIG. 2 is an explanatory diagram of neutron flux distribution in the hollow core.
【図３】本発明に係る中空炉心を設置した高速炉構造の
一例を示す説明図。FIG. 3 is an explanatory view showing an example of a fast reactor structure in which a hollow core according to the present invention is installed.
【図４】炉心空洞部を利用した反応度の自己緩和機構の
一例を示す説明図。FIG. 4 is an explanatory diagram showing an example of a self-relaxation mechanism of reactivity using a core cavity.
【図５】炉心空洞部を利用した反応度の自己緩和機構の
他の例を示す説明図。FIG. 5 is an explanatory diagram showing another example of a self-relaxation mechanism of reactivity using a core cavity.
【図６】炉心空洞部を利用した反応度の自己緩和機構の
更に他の例を示す説明図。FIG. 6 is an explanatory view showing still another example of a self-relaxation mechanism of reactivity using a core cavity.
【図７】12Ｃと14Ｎについての中性子エネルギースペク
トルと中性子吸収断面積を示すグラフ。FIG. 7 is a graph showing neutron energy spectra and neutron absorption cross sections for 12 C and 14 N.
【図８】従来の小型炉心の説明図。FIG. 8 is an explanatory diagram of a conventional small core.
【図９】従来の小型炉心の中性子束分布の説明図。FIG. 9 is an explanatory diagram of a neutron flux distribution in a conventional small core.
【図１０】従来の大型炉心の説明図。FIG. 10 is an explanatory view of a conventional large core.
【図１１】従来の大型炉心の中性子束分布の説明図。FIG. 11 is an explanatory diagram of neutron flux distribution in a conventional large-scale core.
【図１２】炉心の大きさとボイド反応度係数との関係を
示すグラフ。FIG. 12 is a graph showing the relationship between core size and void reactivity coefficient.
１４ 空洞部 １６ 炉心 14 Cavity 16 Core
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｇ２１Ｃ 9/02 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification code Internal reference number FI technical display location G21C 9/02
Claims (6)
料集合体を束ねて全体として円環状に配置し、その円環
状炉心の同一円周上に複数本の制御棒を配列することを
特徴とする高速炉の中空炉心。1. A plurality of fuel assemblies are bundled so as to form a hollow portion in a central portion and arranged in an annular shape as a whole, and a plurality of control rods are arranged on the same circumference of the annular core. The feature is the hollow core of the fast reactor.
料集合体を束ねて全体として円環状に配置し、その空洞
部に冷却材と同等の核的特性を有し且つ冷却材の温度異
常上昇時に溶融落下し、あとがボイドになる可溶融物質
を設置することを特徴とする高速炉の中空炉心。2. A large number of fuel assemblies are bundled and arranged in an annular shape as a whole so that a central portion thereof becomes a hollow portion, and the hollow portion has a nuclear characteristic equivalent to that of a coolant and a temperature of the coolant. A hollow core of a fast reactor, which is equipped with a fusible substance that melts and falls when an abnormal rise occurs, and the rest becomes a void.
料集合体を束ねて全体として円環状に配置し、その空洞
部の上方に中性子吸収体を設置し、出力異常上昇時に前
記中性子吸収体を空洞部に落下させることを特徴とする
高速炉の中空炉心。3. A large number of fuel assemblies are bundled so as to form a hollow portion in the central portion and arranged in an annular shape as a whole, and a neutron absorber is installed above the hollow portion to absorb the neutrons when the output rises abnormally. A hollow core of a fast reactor characterized by dropping a body into a cavity.
料集合体を束ねて全体として円環状に配置し、その空洞
部に、高エネルギー中性子に対する反応断面積が大きい
物質を設置することを特徴とする高速炉の中空炉心。4. A large number of fuel assemblies are bundled and arranged in an annular shape as a whole so that a central portion thereof becomes a cavity, and a substance having a large reaction cross-section for high-energy neutrons is installed in the cavity. The feature is the hollow core of the fast reactor.
料集合体を束ねて全体として円環状に配置した構造をな
し、多数の燃料集合体のうち少なくとも一部に、高エネ
ルギー中性子に対する反応断面積が大きい物質を組み込
んだ燃料を用いることを特徴とする高速炉の中空炉心。5. A structure in which a large number of fuel assemblies are bundled and arranged in an annular shape as a whole so that a central portion becomes a hollow portion, and at least a part of the plurality of fuel assemblies is reacted with high energy neutrons. A hollow core of a fast reactor characterized by using a fuel containing a substance having a large cross-sectional area.
料集合体を束ねて全体として円環状に配置し、その円環
状炉心の下方に、円環状に凹陥した形状のコアキャッチ
ャを設置することを特徴とする高速炉の中空炉心。6. A large number of fuel assemblies are bundled so as to form a hollow portion in the central portion and arranged in an annular shape as a whole, and a core catcher having an annularly concave shape is installed below the annular core. A hollow core of a fast reactor characterized by that.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4027353A JP2551892B2 (en) | 1992-01-18 | 1992-01-18 | Hollow core of fast reactor |
| FR9300348A FR2686444B1 (en) | 1992-01-18 | 1993-01-15 | HOLLOW REACTOR CORE FOR USE IN A FAST REACTOR. |
| RU93004407/25A RU2126558C1 (en) | 1992-01-18 | 1993-01-15 | Heavy-power fast reactor core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4027353A JP2551892B2 (en) | 1992-01-18 | 1992-01-18 | Hollow core of fast reactor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05196771A true JPH05196771A (en) | 1993-08-06 |
| JP2551892B2 JP2551892B2 (en) | 1996-11-06 |
Family
ID=12218678
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4027353A Expired - Fee Related JP2551892B2 (en) | 1992-01-18 | 1992-01-18 | Hollow core of fast reactor |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2551892B2 (en) |
| FR (1) | FR2686444B1 (en) |
| RU (1) | RU2126558C1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110603602A (en) * | 2017-05-09 | 2019-12-20 | 西屋电气有限责任公司 | Annular nuclear fuel pellet with discrete burnable absorber pins |
| CN111508620A (en) * | 2020-04-30 | 2020-08-07 | 中国核动力研究设计院 | Reactor maneuverability self-adjusting method |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2473991C1 (en) * | 2011-12-07 | 2013-01-27 | Открытое акционерное общество "Ордена Трудового Красного Знамени и ордена труда ЧССР опытное конструкторское бюро "Гидропресс" | Nuclear reactor core |
| KR101389840B1 (en) * | 2012-08-29 | 2014-04-29 | 한국과학기술원 | Inherent safety water cooled reactor system for producing electricity |
| RU2549371C1 (en) * | 2014-01-31 | 2015-04-27 | Российская Федерация, от имени которой выступает Государственная корпорация по атомной энергии "Росатом" | Active zone, fuel elements and fuel assembly of fast neutron reactors with lead heat carrier |
| RU2549829C1 (en) * | 2014-01-31 | 2015-04-27 | Российская Федерация, от имени которой выступает Государственная корпорация по атомной энергии "Росатом" | Fast neutron reactor core with lead coolant, fuel rods and fuel assembly for its manufacturing |
| JP7474675B2 (en) * | 2020-10-07 | 2024-04-25 | 三菱重工業株式会社 | Reactor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04335190A (en) * | 1991-05-09 | 1992-11-24 | Japan Atom Power Co Ltd:The | Fast breeder reactor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2395567A1 (en) * | 1977-06-23 | 1979-01-19 | Commissariat Energie Atomique | HEART RECOVERY DEVICE FOR FAST NEUTRON NUCLEAR REACTOR |
| DE3047959A1 (en) * | 1980-12-19 | 1982-07-08 | Hochtemperatur-Reaktorbau GmbH, 5000 Köln | GAS-COOLED BALL HEAD REACTOR |
| US4582675A (en) * | 1982-09-30 | 1986-04-15 | The United States Of America As Represented By The United States Department Of Energy | Magnetic switch for reactor control rod |
| JPH04309893A (en) * | 1991-04-08 | 1992-11-02 | Toshiba Corp | Fast breeder reactor |
-
1992
- 1992-01-18 JP JP4027353A patent/JP2551892B2/en not_active Expired - Fee Related
-
1993
- 1993-01-15 RU RU93004407/25A patent/RU2126558C1/en not_active IP Right Cessation
- 1993-01-15 FR FR9300348A patent/FR2686444B1/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04335190A (en) * | 1991-05-09 | 1992-11-24 | Japan Atom Power Co Ltd:The | Fast breeder reactor |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110603602A (en) * | 2017-05-09 | 2019-12-20 | 西屋电气有限责任公司 | Annular nuclear fuel pellet with discrete burnable absorber pins |
| CN110603602B (en) * | 2017-05-09 | 2023-09-08 | 西屋电气有限责任公司 | Annular nuclear fuel pellets with discrete burnable absorber pins |
| CN111508620A (en) * | 2020-04-30 | 2020-08-07 | 中国核动力研究设计院 | Reactor maneuverability self-adjusting method |
| CN111508620B (en) * | 2020-04-30 | 2023-03-24 | 中国核动力研究设计院 | Reactor maneuverability self-adjusting method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2551892B2 (en) | 1996-11-06 |
| RU2126558C1 (en) | 1999-02-20 |
| FR2686444B1 (en) | 1995-07-13 |
| FR2686444A1 (en) | 1993-07-23 |
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