JPS6331062B2 - - Google Patents
Info
- Publication number
- JPS6331062B2 JPS6331062B2 JP56108641A JP10864181A JPS6331062B2 JP S6331062 B2 JPS6331062 B2 JP S6331062B2 JP 56108641 A JP56108641 A JP 56108641A JP 10864181 A JP10864181 A JP 10864181A JP S6331062 B2 JPS6331062 B2 JP S6331062B2
- Authority
- JP
- Japan
- Prior art keywords
- fuel
- absorbing material
- neutron absorbing
- fuel assembly
- coolant
- 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
- 239000000446 fuel Substances 0.000 claims description 62
- 239000002826 coolant Substances 0.000 claims description 36
- 239000011358 absorbing material Substances 0.000 claims description 28
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims description 12
- 229910052580 B4C Inorganic materials 0.000 claims description 11
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 claims description 11
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 4
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 238000005253 cladding Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 238000010521 absorption reaction Methods 0.000 claims description 3
- 229940075613 gadolinium oxide Drugs 0.000 claims 1
- 229910001938 gadolinium oxide Inorganic materials 0.000 claims 1
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 claims 1
- 239000011521 glass Substances 0.000 claims 1
- 239000011800 void material Substances 0.000 description 28
- 230000009257 reactivity Effects 0.000 description 14
- 239000002574 poison Substances 0.000 description 12
- 231100000614 poison Toxicity 0.000 description 12
- 125000006850 spacer group Chemical group 0.000 description 11
- 239000006096 absorbing agent Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- 238000009835 boiling Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 230000007423 decrease Effects 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 238000002485 combustion reaction Methods 0.000 description 5
- 239000008188 pellet Substances 0.000 description 5
- 230000004907 flux Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 229910052770 Uranium Inorganic materials 0.000 description 3
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 3
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910001093 Zr alloy Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 239000005388 borosilicate glass Substances 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000003758 nuclear fuel Substances 0.000 description 1
- WJWSFWHDKPKKES-UHFFFAOYSA-N plutonium uranium Chemical compound [U].[Pu] WJWSFWHDKPKKES-UHFFFAOYSA-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
- Devices And Processes Conducted In The Presence Of Fluids And Solid Particles (AREA)
- Monitoring And Testing Of Nuclear Reactors (AREA)
Description
【発明の詳細な説明】
本発明は重水減速圧力管型原子炉用燃料集合体
に係り、特に重水減速沸騰水冷却圧力管型原子炉
の炉心核特性を改善すると同時に燃料の燃焼特性
を改善するのに好適な燃料集合体に関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel assembly for a heavy water-moderated pressure tube type nuclear reactor, and particularly to a fuel assembly for a heavy water-moderated, boiling water-cooled pressure tube type nuclear reactor, which improves core characteristics and at the same time improves fuel combustion characteristics. The present invention relates to a fuel assembly suitable for.
従来のこの種燃料集合体は、細径棒状の燃料棒
を同心円状に多数配列し、これらを束ねたクラス
タ型燃料集合体が一般的であつた。この従来の燃
料集合体を用いた重水減速圧力管型原子炉の模式
図を第１図に示す。この型の原子炉の一般的な特
性として、原子炉の起動時、特に冷却材ボイドが
発生し始める高温待機からタービン併入までの低
出力領域において、冷却材ボイド係数があまり正
の値を示すと、中性子束および蒸気ドラム水位が
変動しやすくなり、炉の制御が困難になるという
ことがある。以下その原因を説明する。第１図に
おいて、低出力時には給水管１から比較的冷たい
水が蒸気ドラム２へ送られ、これが下降管３およ
び入口管４を通つて炉心５内の圧力管６内の冷却
材中へ入つて行くため、冷たい水により冷却材中
のボイドがつぶれ、蒸気ドラム２の水位が下降す
る。そして冷却材ボイド係数が正の大きな値のと
きは、この傾向を中性子束の変化を通して加速す
る結果となり、原子炉がスクラムしやすい状態と
なる。冷却材ボイド係数は、プルトニウム・ウラ
ン混合燃料を用いた場合は比較的負であり、上記
問題は生じないが、ウラン燃料を用いた場合は、
冷却材ボイド係数が正となり、上記問題を生じや
すくなる。 Conventional fuel assemblies of this kind have generally been cluster-type fuel assemblies in which a large number of small-diameter rod-shaped fuel rods are arranged concentrically and bundled together. FIG. 1 shows a schematic diagram of a heavy water-moderated pressure tube nuclear reactor using this conventional fuel assembly. A general characteristic of this type of reactor is that the coolant void coefficient shows a very positive value during reactor startup, especially in the low power range from high-temperature standby where coolant voids begin to occur to turbine entry. If this occurs, the neutron flux and steam drum water level may fluctuate easily, making it difficult to control the reactor. The cause will be explained below. In FIG. 1, at low power, relatively cold water is sent from the water supply pipe 1 to the steam drum 2, and this water enters the coolant in the pressure pipe 6 in the reactor core 5 through the downcomer pipe 3 and the inlet pipe 4. As a result, the cold water collapses the voids in the coolant and the water level in the steam drum 2 falls. When the coolant void coefficient has a large positive value, this tendency is accelerated through changes in the neutron flux, making the reactor susceptible to scram. The coolant void coefficient is relatively negative when plutonium-uranium mixed fuel is used, and the above problem does not occur, but when uranium fuel is used,
The coolant void coefficient becomes positive, making the above problem more likely to occur.
最近、冷却材ボイド係数を改善する方法とし
て、特開昭55−135784号で提案されているよう
に、燃料物質中あるいは燃料棒外側に燃料棒に並
行させて可燃性毒物である中性子吸収材を燃料棒
の長手方向全領域に装荷する方法が知られてい
る。この方法は、圧力管６内の冷却材中にボイド
がない場合は熱中性子束が大きく減少するのに対
し、ボイド発生とともに圧力管６内熱中性子束が
増大する効果を利用し、圧力管６内に中性子吸収
材を置くことによつてボイドに対して負の反応度
投入効果をもたらすことを応用したものである。 Recently, as a method to improve the coolant void coefficient, as proposed in Japanese Patent Application Laid-Open No. 135784/1984, a neutron absorbing material, which is a burnable poison, is added in the fuel material or on the outside of the fuel rods in parallel with the fuel rods. A method is known in which the entire length of the fuel rod is loaded. This method utilizes the effect that the thermal neutron flux inside the pressure tube 6 increases with the generation of voids, whereas the thermal neutron flux decreases greatly when there are no voids in the coolant inside the pressure tube 6. This is an application of the fact that by placing a neutron absorbing material inside the void, a negative reactivity injection effect is brought about.
しかし、この方法で冷却材ボイド係数をより負
にする場合は、運転サイクルを通じて効果を維持
するために、可燃性毒物の濃度を高めてサイクル
末期まで可燃性毒物を燃え残す構成とする必要が
ある。この結果として、そのままでは燃料の達成
燃焼度が低下するため、燃料の核燃料濃度を増大
させ、燃焼度を維持する必要があつた。なお、冷
却材ボイド係数をより負にするために中性子吸収
材として可燃性毒物を用いた理由は、中性子吸収
材を用いない燃料の冷却材ボイド係数が運転サイ
クル初期よりもサイクル末期の方が負側に移行す
るため、運転サイクル初期では、冷却材ボイド係
数の負側への移行幅を大きくさせる必要があるた
めである。サイクル中期から末期にかけては、冷
却材ボイド係数はより負側に移行するが、必要値
よりも正側の場合は、可燃性毒物を燃え残すよう
に装荷することによりボイド係数を調整すること
ができる。この場合は燃焼度が低下するために燃
焼度の低下を減少させることが望まれていた。 However, if this method is used to make the coolant void coefficient more negative, it is necessary to increase the concentration of burnable poisons and create a configuration in which the burnable poisons are left to burn until the end of the cycle in order to maintain effectiveness throughout the operating cycle. . As a result, the achieved burnup of the fuel would decrease if left as is, so it was necessary to increase the nuclear fuel concentration of the fuel to maintain the burnup. The reason why a burnable poison was used as a neutron absorber to make the coolant void coefficient more negative is that the coolant void coefficient of fuel that does not use a neutron absorber is more negative at the end of the cycle than at the beginning of the cycle. This is because, in the early stage of the operation cycle, it is necessary to increase the width of the shift of the coolant void coefficient to the negative side. From the middle to the end of the cycle, the coolant void coefficient shifts to a more negative side, but if it is more positive than the required value, the void coefficient can be adjusted by loading burnable poison so that it remains unburned. . In this case, since the burnup decreases, it has been desired to reduce the decrease in the burnup.
本発明は上記に鑑みてなされたもので、その目
的とするところは、低出力時の冷却材ボイド反応
度係数をさらに負側にすることができ、同時に燃
料の達成燃焼度をさらに向上することができる重
水減速圧力管型原子炉用燃料集合体を提供するこ
とにある。 The present invention has been made in view of the above, and its purpose is to make it possible to make the coolant void reactivity coefficient at low power even more negative, and at the same time to further improve the achieved burnup of the fuel. An object of the present invention is to provide a fuel assembly for a heavy water moderating pressure tube type nuclear reactor that can be used in a nuclear reactor.
本発明は重水減速沸騰水冷却圧力管型原子炉の
冷却材ボイド率変化による炉心反応度変化が冷却
材流路の沸騰開始点以降の下流側で生じることに
着目してなされたもので、沸騰開始点より下流側
である燃料集合体の炉心有効長の冷却材下流側2/
３の領域の範囲内に中性子吸収材を装荷したこと
を特徴としている。 The present invention was developed by focusing on the fact that changes in core reactivity due to changes in coolant void ratio in heavy water-moderated boiling water-cooled pressure tube reactors occur downstream of the point at which boiling starts in the coolant flow path. Coolant downstream of the core effective length of the fuel assembly downstream from the starting point 2/
It is characterized in that a neutron absorbing material is loaded within the range of region 3.
以下本発明を第２図、第３図に示した実施例お
よび第４図ないし第６図を用いて詳細に説明す
る。 The present invention will be explained in detail below with reference to the embodiments shown in FIGS. 2 and 3 and FIGS. 4 to 6.
第２図は本発明の燃料集合体の一実施例を示す
中央部分縦断面図である。第２図の燃料集合体
は、同心円状に多数の燃料棒が配置されたクラス
タ型燃料集合体で燃料ペレツト７と燃料ペレツト
７を包む被覆管８とによりなる細径棒状の多数の
燃料棒、被覆管８を束ねている燃料スペーサ９、
燃料棒の上部、下部をそれぞれ固定する上部タイ
プレート１０、下部タイプレート１１および中央
部に配設され、燃料スペーサ９の間隔を保つため
のスペーサタイロツド１２とから構成してある。
ところで、第２図に示す実施例では、スペーサタ
イロツド１２の上部には炭化ボロンの粉末よりな
る中性子吸収材１３を収納してある。 FIG. 2 is a longitudinal cross-sectional view of the center portion of an embodiment of the fuel assembly of the present invention. The fuel assembly shown in FIG. 2 is a cluster type fuel assembly in which a large number of fuel rods are arranged concentrically, and includes a large number of small diameter rod-shaped fuel rods made up of fuel pellets 7 and a cladding tube 8 that encloses the fuel pellets 7. a fuel spacer 9 bundling the cladding tube 8;
It consists of an upper tie plate 10, a lower tie plate 11, which fixes the upper and lower parts of the fuel rods, respectively, and a spacer tie rod 12, which is disposed in the center and maintains the spacing between the fuel spacers 9.
In the embodiment shown in FIG. 2, a neutron absorbing material 13 made of boron carbide powder is housed in the upper part of the spacer tie rod 12.
第３図は第２図のスペーサタイロツド１２の一
実施例を示す縦断面図である。スペーサタイロツ
ド１２は、２本のジルカロイ合金製の円管１４を
連結用端栓１５にネジ込み結合し、２本の円管１
４の上部、下部にはそれぞれタイプレート固定用
端栓１６が溶接してあり、上部の円管１４内には
炭化ボロン１７よりなる中性子吸収材１３を中性
子吸収材収納管１８に収納した状態で納めた構成
としてある。なお、収納管１８内の炭化ボロン１
７は端栓１９により密封されており、かつ、収納
管１８の中には炭化ボロン１７から発生するガス
をためる空間がばね２０によつて確保してある。
このようにして、中性子吸収材である炭化ボロン
１７を収納してある部分の長さは、炉心の有効長
の約1/2としてあり、かつ、軸方向上部である下
流側に収納してある。そして下部の円管１４の内
部には冷却材が流れる構造としてあり、また、
上、下部のそれぞれの円管１４にはスペーサ保持
用の突起２１が溶接してある。 FIG. 3 is a longitudinal sectional view showing one embodiment of the spacer tie rod 12 of FIG. The spacer tie rod 12 connects two circular tubes 14 made of Zircaloy alloy to a connecting end plug 15 by screwing them together.
End plugs 16 for fixing the tie plate are welded to the upper and lower parts of 4, respectively, and a neutron absorbing material 13 made of boron carbide 17 is housed in a neutron absorbing material storage tube 18 in the upper circular tube 14. It is in the configured configuration. Note that the boron carbide 1 in the storage tube 18
7 is sealed by an end plug 19, and a space is secured in the storage tube 18 by a spring 20 to store the gas generated from the boron carbide 17.
In this way, the length of the part where boron carbide 17, which is a neutron absorbing material, is stored is approximately 1/2 of the effective length of the reactor core, and it is stored at the upper downstream side in the axial direction. . There is a structure in which a coolant flows inside the lower circular pipe 14, and
A projection 21 for holding a spacer is welded to each of the upper and lower circular tubes 14.
第４図は沸騰水冷却圧力管型原子炉における炉
心出力と冷却材の沸騰開始点位置との開係を示す
線図で、沸騰開始点位置は炉心の軸方向有効距離
で示してある。第４図によれば、軸方向有効距離
1850mmで冷却材が沸騰を開始するのは、炉心出力
が約20％のときとなる。すなわち、炉心出力20％
以下の低出力では、冷却材ボイドの変化は、炉心
軸方向上半分で生じ、冷却材ボイド変化による反
応度変化も炉心の上半分で生じることになる。し
たがつて、炉心出力が約20％以下では、燃料集合
体の有効長全長にわたつて中性子吸収材を装荷し
た場合と、上記した実施例のように有効長の上部
半分に装荷した場合とで、冷却材ボイド反応度係
数をより負にする効果は同じになる。 FIG. 4 is a diagram showing the relationship between the core output and the boiling start point position of the coolant in a boiling water cooled pressure tube reactor, and the boiling start point position is shown in terms of the effective distance in the axial direction of the core. According to Figure 4, the effective axial distance
The coolant starts boiling at 1850 mm when the core power is approximately 20%. i.e. core power 20%
At the following low power, changes in coolant voids occur in the upper half of the core in the axial direction, and changes in reactivity due to changes in coolant voids also occur in the upper half of the core. Therefore, when the core power is about 20% or less, the difference between loading the neutron absorbing material over the entire effective length of the fuel assembly and loading it in the upper half of the effective length as in the above example is shown. , the effect of making the coolant void reactivity coefficient more negative will be the same.
第５図はウラン燃料の場合の炉心出力と冷却材
ボイド反応度係数差との関係を示す線図で、約２
％濃度の微濃縮ウラン燃料を用い、炭化ボロン１
７の中の中性子吸収材であるボロン同位元素（質
量約10）の原子数密度を新燃料時に約１×1021
個／cm3とし、燃焼サイクル末期に対応する約
13GWD／Ｔ燃焼した時点のものを示してある。
第５図において、ａ曲線は中性子吸収材を装荷し
ない場合、ｂ曲線は中性子吸収材を有効長全長に
装荷した場合、ｃ曲線は本発明の実施例のように
中性子吸収材を軸方向上半分に装荷した場合の特
性であり、中性子吸収材を装荷しない燃料の炉心
出力０％における冷却材ボイド反応度係数を基準
（零）として示してある。なお、この図の約
13GWD／Ｔの燃焼時点における中性子吸収材
（ボロン）の原子数密度は約２×1020個／cm3であ
る。 Figure 5 is a diagram showing the relationship between core power and coolant void reactivity coefficient difference in the case of uranium fuel.
% concentration of slightly enriched uranium fuel, boron carbide 1
The atomic number density of boron isotope (mass approximately 10), which is a neutron absorber in 7, is approximately 1×10 21 when new fuel is used.
pcs/ cm3 , corresponding to the end of the combustion cycle.
The figure is shown at the time of 13GWD/T combustion.
In FIG. 5, curve a shows the case where no neutron absorbing material is loaded, curve b shows the case where the neutron absorbing material is loaded over the entire effective length, and curve c shows the case where the neutron absorbing material is loaded in the upper half in the axial direction as in the embodiment of the present invention. The characteristics are shown based on the coolant void reactivity coefficient at 0% core output of fuel without loading a neutron absorber (zero). In addition, in this figure, approx.
The atomic number density of the neutron absorbing material (boron) at the time of combustion of 13 GWD/T is approximately 2×10 20 atoms/cm 3 .
第５図より、中性子吸収材を装荷した方が装荷
しない場合よりも−４×10-5ΔK／Ｋ／ボイド程
度冷却材ボイド反応度係数を負にしていることが
わかる。また、炉心出力20％程度までは、中性子
吸収材を有効長全長に装荷した場合と軸方向上半
分に装荷した場合とで冷却材ボイド反応度係数差
が全く同一で、炉心出力が20％以上であつても、
それが約40％程度までは、両者の間の差がわずか
であることがわかる。なお、炉心出力が約40％以
上では、冷却材ボイド反応度係数の出力係数に対
する重みが小さくなるため、冷却材ボイド反応度
係数差が多少正方向に向つても炉心の出力上昇制
御上特に問題になることはない。 From FIG. 5, it can be seen that loading the neutron absorber makes the coolant void reactivity coefficient more negative by about -4×10 −5 ΔK/K/void than when loading the neutron absorber. In addition, up to about 20% of the core power, the difference in the coolant void reactivity coefficient is exactly the same when the neutron absorber is loaded over the entire effective length and when it is loaded in the upper half in the axial direction, and the core power is 20% or more. Even if it is,
It can be seen that the difference between the two is small up to about 40%. Note that when the core power is approximately 40% or higher, the weight of the coolant void reactivity coefficient on the output coefficient becomes smaller, so even if the difference in the coolant void reactivity coefficient is slightly positive, it is especially problematic in controlling the increase in core power. It will never become.
次に、本発明の実施例のように中性子吸収材を
軸方向上半分に装荷するようにすると、有効長全
長にわたつて装荷した場合より有利になる点につ
いて説明する。 Next, it will be explained that loading the neutron absorbing material in the upper half in the axial direction as in the embodiment of the present invention is more advantageous than loading it over the entire effective length.
第６図は燃料取出時の燃料集合体中央部の中性
子吸収材（ボロン）の原子数密度と取出平均燃焼
度差との関係線図で、ｄ曲線は中性子吸収材を有
効長全長に装荷した場合、ｅ曲線は軸方向上半分
に装荷した場合の特性曲線である。第６図に示す
ように、中性子吸収材を有効長全長に装荷した場
合より本発明に係るように軸方向上半分に装荷し
た方が取出平均燃焼度差が向上する。例えば、燃
料取出時の中性子吸収材の原子数密度が２×1020
個／cm3の場合、中性子吸収材を有効長全長に装荷
した場合、燃焼度が約3.5GWD／Ｔ低下するのに
対し、軸方向上半分に装荷した場合のそれは、約
1.6GWD／Ｔの低下にとどまり、約2GWD／Ｔだ
け燃焼度が向上する。 Figure 6 is a relationship diagram between the atomic number density of the neutron absorber (boron) in the center of the fuel assembly at the time of fuel removal and the average burnup difference. In this case, the e-curve is the characteristic curve when the upper half in the axial direction is loaded. As shown in FIG. 6, the average extraction burnup difference is improved when the neutron absorber is loaded in the upper half in the axial direction as in the present invention than when the neutron absorber is loaded over the entire effective length. For example, the atomic number density of the neutron absorbing material at the time of fuel removal is 2×10 20
When the neutron absorption material is loaded over the entire effective length , the burnup decreases by about 3.5GWD/T, whereas when it is loaded in the upper half in the axial direction, the burnup decreases by about 3.5GWD/T.
The decrease is only 1.6GWD/T, and burnup increases by about 2GWD/T.
上記したように、本発明の実施例によれば、原
子炉起動時の低出力時の冷却材ボイド反応度係数
をさらに負側にすることができ、起動時の運転制
御を容易にできる。また、燃料の達成燃焼度を従
来と同一の濃縮度でさらに向上することができ
る。 As described above, according to the embodiments of the present invention, the coolant void reactivity coefficient at low power during reactor startup can be made more negative, and operation control during startup can be facilitated. Further, the achieved burnup of the fuel can be further improved with the same enrichment as before.
なお、上記した実施例では、中性子吸収材とし
て炭化ボロンの粉末を用いたが、炭化ボロンの焼
結ペレツトあるいはほうけい酸ガラスを用いるよ
うにしてもよく、同様の効果を得ることができ
る。また、中性子吸収材である炭化ボロン１７を
燃料集合体径方向中央のスペーサタイロツド１２
の上部円管１４内に収納するようにしたが、燃料
棒の軸方向上部1/2の燃料ペレツト中に中性子吸
収材を混入するようにしてもよく、ただし、この
場合は中性子吸収材として酸化ガドリニウムを用
いる。このようにしても、上記した実施例と同一
の効果が得られる。また、実施例では中性子吸収
材を軸方向上半分に装荷したが、下流側2/3の領
域の範囲内であれば、同様の効果がある。 Although boron carbide powder is used as the neutron absorbing material in the above-described embodiment, sintered boron carbide pellets or borosilicate glass may also be used, and similar effects can be obtained. In addition, boron carbide 17, which is a neutron absorbing material, is attached to the spacer tie rod 12 in the radial center of the fuel assembly.
Although the neutron absorbing material is housed in the upper circular tube 14 of the fuel rod, it is also possible to mix the neutron absorbing material into the fuel pellets in the upper half of the fuel rod in the axial direction.However, in this case, oxidized neutron absorbing material Uses gadolinium. Even in this case, the same effect as the above embodiment can be obtained. Further, in the example, the neutron absorbing material was loaded in the upper half in the axial direction, but the same effect can be obtained as long as it is within the range of two-thirds of the region on the downstream side.
なお、本発明の実施例において、中性子吸収材
として可燃性毒物を用いた場合の効果を下記に示
す。 In addition, in the examples of the present invention, the effects when a burnable poison is used as a neutron absorbing material are shown below.
(1) 可燃性毒物は、中性子吸収が極めて大きく、
冷却材ボイド係数を負側に移行させる効果が著
しい。(1) Burnable poisons have extremely high neutron absorption;
The effect of shifting the coolant void coefficient to the negative side is significant.
(2) サイクルを通じてボイド係数を負にする場
合、サイクル末期まで可燃性毒物を燃え残す必
要があるが、これは毒物の装荷濃度を高くする
ことにより任意に調整が可能で、サイクルを通
じてのボイド係数低減を実現できる。また、こ
の際、ボイド係数低減上、ボイドが発生しない
ため無関係な燃料下部には可燃性毒物を装荷し
ないため、軸方向全長に可燃性毒物を装荷する
従来の場合よりも燃焼度を改善できる。(2) In order to make the void coefficient negative throughout the cycle, it is necessary to leave the burnable poison unburned until the end of the cycle, but this can be adjusted arbitrarily by increasing the loading concentration of the poison. reduction can be achieved. In addition, in this case, in order to reduce the void coefficient, since no voids are generated, burnable poison is not loaded in the lower part of the unrelated fuel, so burnup can be improved compared to the conventional case where burnable poison is loaded over the entire axial length.
(3) サイクル初期は、一般的に新燃料に出力ピー
クが発生し、熱的に厳しくなるが、本発明の実
施例では、軸方向上部2/3の範囲に可燃性毒物
を配置したため、新燃料軸方向上部の出力を低
下させることができる。(3) At the beginning of the cycle, the new fuel generally has an output peak and becomes thermally severe, but in the embodiment of the present invention, the burnable poison is placed in the upper two-thirds of the axial direction, so the new fuel It is possible to reduce the output of the upper part of the fuel in the axial direction.
以上説明したように、本発明によれば、低出力
時の冷却材ボイド反応度係数をさらに負側にする
ことができ、原子炉起動時の運転制御を容易にで
き、かつ、燃料の達成燃焼度をさらに向上するこ
とができるという効果がある。 As explained above, according to the present invention, the coolant void reactivity coefficient at low power can be made more negative, operation control at reactor startup can be facilitated, and the achieved fuel combustion This has the effect of further improving the level of performance.
第１図は重水減速圧力管型原子炉の模式図、第
２図は本発明の重水減速圧力管型原子炉用燃料集
合体の一実施例を示す中央部分縦断面図、第３図
は第２図のスペーサタイロツドの一実施例を示す
縦断面図、第４図は炉心出力と冷却材の沸騰開始
点位置との関係を示す線図、第５図は炉心出力と
冷却材ボイド反応度係数の差との関係を示す線
図、第６図は中性子吸収材の原子数密度と取出平
均燃焼度差との関係線図である。
７……燃料ペレツト、８……被覆管、９……燃
料スペーサ、１２……スペーサタイロツド、１３
……中性子吸収材、１４……円管、１５……連結
用端栓、１７……炭化ボロン、１８……収納管。
FIG. 1 is a schematic diagram of a heavy water-moderated pressure tube type nuclear reactor, FIG. 2 is a vertical cross-sectional view of a central portion showing an embodiment of a fuel assembly for a heavy water-moderated pressure tube type nuclear reactor according to the present invention, and FIG. Figure 2 is a vertical cross-sectional view showing an example of the spacer tie rod, Figure 4 is a diagram showing the relationship between core power and the boiling start point position of the coolant, and Figure 5 is a diagram showing the relationship between core power and coolant void reactivity. FIG. 6 is a diagram showing the relationship between the coefficient difference and the atomic number density of the neutron absorbing material and the extraction average burnup difference. 7... Fuel pellet, 8... Cladding tube, 9... Fuel spacer, 12... Spacer tie rod, 13
... Neutron absorbing material, 14 ... Circular tube, 15 ... Connection end plug, 17 ... Boron carbide, 18 ... Storage tube.
Claims (1)
炉用燃料集合体において、該燃料集合体の炉心有
効長の冷却材下流側2/3の領域の範囲内に中性子
吸収材を装荷してなることを特徴とする重水減速
圧力管型原子炉用燃料集合体。 ２ 前記中性子吸収材が前記燃料棒に沿つて配置
してあり、中性子吸収材として炭化ほう素あるい
はほう素を含むガラスを用い、該中性子吸収材の
周囲を被覆管で包んである特許請求の範囲第１項
記載の重水減速圧力管型原子炉用燃料集合体。 ３ 前記中性子吸収材が燃料集合体の中央位置に
装荷してある特許請求の範囲第２項記載の重水減
速圧力管型原子炉用燃料集合体。 ４ 前記中性子吸収材は酸化ガドリニウムよりな
り前記燃料棒の燃料物質中に添加してある特許請
求の範囲第１項記載の重水減速圧力管型原子炉用
燃料集合体。[Scope of Claims] 1. In a fuel assembly for a heavy water moderated pressure tube type nuclear reactor consisting of a large number of fuel rods, neutron absorption occurs within the range of two-thirds of the coolant downstream side of the effective length of the reactor core of the fuel assembly. A fuel assembly for a heavy water moderating pressure tube type nuclear reactor, characterized by being loaded with material. 2. The neutron absorbing material is arranged along the fuel rod, boron carbide or glass containing boron is used as the neutron absorbing material, and the neutron absorbing material is surrounded by a cladding tube. The fuel assembly for a heavy water moderating pressure tube type nuclear reactor according to item 1. 3. The fuel assembly for a heavy water moderating pressure tube type nuclear reactor according to claim 2, wherein the neutron absorbing material is loaded at a central position of the fuel assembly. 4. The fuel assembly for a heavy water moderating pressure tube type nuclear reactor according to claim 1, wherein the neutron absorbing material is made of gadolinium oxide and is added to the fuel material of the fuel rod.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56108641A JPS5810678A (en) | 1981-07-10 | 1981-07-10 | Fuel assembly for heavy water moderated pressure tube type reactor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56108641A JPS5810678A (en) | 1981-07-10 | 1981-07-10 | Fuel assembly for heavy water moderated pressure tube type reactor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5810678A JPS5810678A (en) | 1983-01-21 |
| JPS6331062B2 true JPS6331062B2 (en) | 1988-06-22 |
Family
ID=14489940
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56108641A Granted JPS5810678A (en) | 1981-07-10 | 1981-07-10 | Fuel assembly for heavy water moderated pressure tube type reactor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5810678A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5811163A (en) * | 1981-07-11 | 1983-01-21 | Nippon Telegr & Teleph Corp <Ntt> | Color recording by ink jet printer |
| JPS5967060A (en) * | 1982-10-07 | 1984-04-16 | Ricoh Co Ltd | Color recorder |
-
1981
- 1981-07-10 JP JP56108641A patent/JPS5810678A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5811163A (en) * | 1981-07-11 | 1983-01-21 | Nippon Telegr & Teleph Corp <Ntt> | Color recording by ink jet printer |
| JPS5967060A (en) * | 1982-10-07 | 1984-04-16 | Ricoh Co Ltd | Color recorder |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5810678A (en) | 1983-01-21 |
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