JPH0363719B2 - - Google Patents
Info
- Publication number
- JPH0363719B2 JPH0363719B2 JP58016564A JP1656483A JPH0363719B2 JP H0363719 B2 JPH0363719 B2 JP H0363719B2 JP 58016564 A JP58016564 A JP 58016564A JP 1656483 A JP1656483 A JP 1656483A JP H0363719 B2 JPH0363719 B2 JP H0363719B2
- Authority
- JP
- Japan
- Prior art keywords
- coolant
- fuel assembly
- fuel
- sampling
- damage
- 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
- 239000000446 fuel Substances 0.000 claims description 129
- 239000002826 coolant Substances 0.000 claims description 88
- 238000005070 sampling Methods 0.000 claims description 32
- 238000001514 detection method Methods 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 9
- 238000001816 cooling Methods 0.000 claims description 3
- 230000002285 radioactive effect Effects 0.000 claims description 3
- 238000011109 contamination Methods 0.000 claims description 2
- 238000007789 sealing Methods 0.000 claims description 2
- 230000000717 retained effect Effects 0.000 claims 1
- 230000004992 fission Effects 0.000 description 33
- 238000010586 diagram Methods 0.000 description 7
- 238000005253 cladding Methods 0.000 description 6
- 230000000712 assembly Effects 0.000 description 5
- 238000000429 assembly Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000003758 nuclear fuel Substances 0.000 description 3
- 238000009835 boiling Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 206010073306 Exposure to radiation Diseases 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000008213 purified water Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 230000002123 temporal effect Effects 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】
〔発明の技術分野〕
本発明は、原子炉用燃料の破損検出方法に係
り、特に燃料集合体内の冷却材をサンプリングし
て燃料破損が生じていないかどうかを検出する燃
料破損検出方法に関する。[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for detecting damage to fuel for a nuclear reactor, and particularly to a method for detecting fuel damage by sampling coolant in a fuel assembly. Relating to a method for detecting fuel damage.
一般に、原子炉容器内には多数の燃料集合体が
配設され炉心部が構成されており、その各燃料集
合体内に、金属製の被覆管内に核燃料を挿入密封
した複数本の燃料棒が配列せしめられている。
Generally, a large number of fuel assemblies are arranged inside a nuclear reactor vessel to make up the reactor core, and within each fuel assembly, multiple fuel rods with nuclear fuel inserted and sealed inside metal cladding tubes are arranged. I'm being forced to do it.
すなわち、核燃料は金属製の被覆管によつて密
封され、核分裂によつて発生する有害な核分裂生
成物が冷却材中に拡散しないようにしてある。 That is, the nuclear fuel is sealed with a metal cladding tube to prevent harmful fission products generated by nuclear fission from diffusing into the coolant.
しかしながら、被覆管の腐蝕や局所的な応力の
発生または製造上の欠陥等によつて、原子炉運転
中に燃料棒の被覆管が破損したような場合には、
核燃料の核分裂によつて発生する核分裂生成物が
冷却材中に拡散し、冷却材のみならず原子炉系機
器やタービン系機器等が放射能で汚染される可能
性がある。したがつて、破損した燃料棒を有する
燃料集合体の有無を時々点検し、破損した燃料棒
を有する燃料集合体がある場合には、当該燃料集
合体を新らしいものと交換する必要がある。 However, if the fuel rod cladding is damaged during reactor operation due to corrosion of the cladding, localized stress, or manufacturing defects,
Fission products generated by fission of nuclear fuel diffuse into the coolant, potentially contaminating not only the coolant but also nuclear reactor equipment, turbine equipment, etc. with radioactivity. Therefore, it is necessary to check from time to time whether there is a fuel assembly with a damaged fuel rod, and if there is a fuel assembly with a damaged fuel rod, it is necessary to replace the fuel assembly with a new one.
ところで、燃料集合体の燃料棒被覆管の破損の
有無は、原子炉を通過する冷却材をサンプリング
して冷却材中に含まれる核分裂生成物の濃度を測
定して検出することができる。しかし、多数ある
燃料集合体の中から破損している燃料棒を有する
燃料集合体を検出するためには、各燃料集合体に
ついて個別にその破損検出を行なわなければなら
ない。しかも、燃料集合体の燃料棒に破損がある
場合には、不用意な取り扱いにより作業員が被爆
を受ける可能性があり、炉内機器も汚染される可
能性がある。そのため破損燃料集合体の検出は原
子炉内で行なうことが望ましい。 Incidentally, the presence or absence of damage to the fuel rod cladding of a fuel assembly can be detected by sampling the coolant passing through the reactor and measuring the concentration of fission products contained in the coolant. However, in order to detect a fuel assembly having a damaged fuel rod from among a large number of fuel assemblies, it is necessary to individually perform damage detection for each fuel assembly. Moreover, if a fuel rod in a fuel assembly is damaged, there is a possibility that workers may be exposed to radiation due to careless handling, and equipment within the reactor may also be contaminated. Therefore, it is desirable to detect damaged fuel assemblies inside the reactor.
第１図は、沸騰水型原子炉における燃料破損検
出方法の概略説明図であつて、符号１はチヤンネ
ルボツクス２内に概略的に示す燃料棒群３を装着
した燃料集合体であり、その燃料集合体１は炉心
支持板４上に支持装着されている。一方、冷却材
は上記炉心支持板４の下方から、上記燃料集合体
１のチヤンネルボツクス２の内外に流通せしめら
れ、その冷却材によつて燃料の核分裂により発生
する崩壊熱が冷却除去される。 FIG. 1 is a schematic explanatory diagram of a fuel failure detection method in a boiling water reactor, in which reference numeral 1 is a fuel assembly in which a group of fuel rods 3 schematically shown in a channel box 2 are mounted, and the fuel The assembly 1 is supported and mounted on a core support plate 4. On the other hand, a coolant is made to flow into and out of the channel box 2 of the fuel assembly 1 from below the core support plate 4, and decay heat generated by nuclear fission of the fuel is cooled and removed by the coolant.
ところで、このような原子炉において燃料棒の
破損の検出に際しては、燃料集合体１の上端部
に、空気管５とサンプリング管６とが取り付けら
れキヤツプ７を装着する。そして、上記空気管５
を通してキヤツプ７内に空気を供給し、キヤツプ
７内に空気層８を形成する。したがつて、この空
気層８によつて燃料集合体１内の上部に液面９が
形成されるとともに、燃料集合体１内に流入する
冷却材の流れが阻止される。 By the way, when detecting damage to a fuel rod in such a nuclear reactor, an air pipe 5 and a sampling pipe 6 are attached to the upper end of the fuel assembly 1, and a cap 7 is attached. And the air pipe 5
Air is supplied into the cap 7 through the cap 7 to form an air layer 8 within the cap 7. Therefore, this air layer 8 forms a liquid level 9 in the upper part of the fuel assembly 1, and at the same time, the flow of the coolant flowing into the fuel assembly 1 is blocked.
そこで、このような状態で一定時間保持する
と、燃料棒３の温度が上昇し、燃料棒３の被覆管
上に破損があると破損部から冷却材中に核分裂生
成物が放出され易くなり、また冷却材も加熱さ
れ、燃料集合体１内で冷却材が自然対流によつて
循環し、上記核分裂生成物が冷却材中に溶け込み
ながら燃料集合体１の内部を拡散していく。 Therefore, if this condition is maintained for a certain period of time, the temperature of the fuel rod 3 will rise, and if there is a break on the cladding tube of the fuel rod 3, fission products will be likely to be released from the break into the coolant. The coolant is also heated, and the coolant circulates within the fuel assembly 1 by natural convection, and the fission products diffuse inside the fuel assembly 1 while dissolving into the coolant.
しかして、上記一定時間経過後、燃料集合体１
の上部に被冠したキヤツプ７に取り付けてあるサ
ンプリング管６を経て冷却材を炉外に採取し、そ
の採取した冷却材中の放射能濃度を測定すること
によつて燃料集合体の破損の有無を検出する。 However, after the above-mentioned certain period of time has elapsed, the fuel assembly 1
Coolant is collected outside the reactor through a sampling pipe 6 attached to a cap 7 that is capped on top of the reactor, and the presence or absence of damage to the fuel assembly is determined by measuring the radioactivity concentration in the collected coolant. Detect.
しかしながら、このような燃料破損検出方法に
おいては、下記のような不都合がある。すなわ
ち、破損燃料の検出作業は、炉内の放射能濃度の
低下待ちや水張り遮へい作業等のために炉停止後
５〜７日経過してから行なわれるため、崩壊熱量
は小さく核分裂生成物の放出量も極めて少なくな
つた状態にある。しかも核分裂生成物は燃料集合
体内を冷却材の自然対流によつて拡散する。その
ためサンプリングを行なつている燃料集合体下部
に核分裂生成物が放出された場合、その核分裂生
成物が溶け込んだ冷却材がサンプリング管６が挿
入されている燃料集合体上部に到達するまでに長
時間を要し、また燃料集合体内で生じる自然対流
の流動如何によつては燃料集合体下部の冷却材が
上部に到達することがなく、燃料集合体の中途で
冷却材が逆流して、核分裂生成物のサンプリング
が十分に行なえない等の問題がある。 However, such a fuel damage detection method has the following disadvantages. In other words, the detection of damaged fuel is carried out 5 to 7 days after the reactor has been shut down in order to wait for the radioactive concentration inside the reactor to decrease and to perform water-filling shielding work, so the amount of decay heat is small and the release of fission products is difficult. The amount is also extremely low. Moreover, the fission products diffuse within the fuel assembly due to the natural convection of the coolant. Therefore, if fission products are released into the lower part of the fuel assembly where sampling is being performed, it will take a long time for the coolant in which the fission products are dissolved to reach the upper part of the fuel assembly where the sampling tube 6 is inserted. Also, depending on the flow of natural convection that occurs within the fuel assembly, the coolant at the bottom of the fuel assembly may not reach the top, and the coolant may flow backwards in the middle of the fuel assembly, causing nuclear fission. There are problems such as insufficient sampling of objects.
本発明はこのような点に鑑み、比較的核分裂生
成物の流出が少なくしかも燃料集合体下部で核分
裂生成物が放出された場合においても、十分上記
核分裂生成物を含有した冷却材をサンプリング
し、核分裂生成物の有無の検出精度が高い燃料破
損検出方法を得ることを目的とする。
In view of these points, the present invention provides a method for sampling a coolant sufficiently containing the fission products even when the outflow of fission products is relatively small and the fission products are released at the lower part of the fuel assembly. The purpose of this invention is to obtain a fuel damage detection method with high accuracy in detecting the presence or absence of nuclear fission products.
本発明は、原子炉容器内に装架されている燃料
集合体の頂端部を、空気管およびサンプリング管
を設けたキヤツプで覆いそのキヤツプ内に空気を
封入することによつて、燃料集合体の下方より流
入し上方に流出する冷却材流れを停止させ、その
状態を一定時間保持させた後燃料集合体上部の空
気層を排除し、燃料集合体内の冷却材流れを再開
させ、燃料集合体内に滞留していた冷却材を所定
時間サンプリングし、サンプリングした冷却材の
放射能測定により燃料棒の破損の有無を検出する
ことを特徴とする。
The present invention covers the top end of a fuel assembly installed in a reactor vessel with a cap provided with an air pipe and a sampling pipe, and seals air in the cap. The flow of coolant flowing in from below and flowing upward is stopped, and after this state is maintained for a certain period of time, the air layer above the fuel assembly is removed, and the flow of coolant within the fuel assembly is restarted. It is characterized by sampling the stagnant coolant for a predetermined period of time and detecting the presence or absence of damage to the fuel rods by measuring the radioactivity of the sampled coolant.
以下、第２図乃至第６図を参照して本発明の一
実施例について説明する。
An embodiment of the present invention will be described below with reference to FIGS. 2 to 6.
第２図は燃料破損検出装置の概略構成図であつ
て、原子炉の点検等に際しては原子炉の作動停止
後、原子炉容器１０の上蓋が取り外されるととも
に、残留熱除去系によつて冷却材が原子炉容器に
供給され、上記原子炉容器１０内に配設された炉
心１１部の冷却が行なわれる。すなわち、残留熱
除去系ポンプ１２の始動によつて圧力抑制室等の
冷却材源１３から冷却材が汲み上げられ熱交換器
１４で冷却された後原子炉容器１０内に供給され
る。上記冷却材温度は30〜40℃程度であつて、こ
の冷却材によつて炉心１１の異常な温度上昇を防
ぐとともに、炉心１１を構成する燃料集合体から
放出される核分裂生成物の量を少なくし、作業員
の放射能被曝の危険性が減少せしめられる。 FIG. 2 is a schematic diagram of the fuel failure detection system. When inspecting the reactor, after the reactor has stopped operating, the top cover of the reactor vessel 10 is removed, and the coolant is removed by the residual heat removal system. is supplied to the reactor vessel, and a portion of the reactor core 11 disposed within the reactor vessel 10 is cooled. That is, by starting the residual heat removal system pump 12, coolant is pumped up from a coolant source 13 such as a pressure suppression chamber, cooled by a heat exchanger 14, and then supplied into the reactor vessel 10. The temperature of the coolant is about 30 to 40 degrees Celsius, and this coolant prevents abnormal temperature rises in the core 11 and reduces the amount of fission products released from the fuel assemblies that make up the core 11. This reduces the risk of radiation exposure for workers.
ところで、炉心１１を構成する多数本の燃料集
合体の任意の一つに順次燃料破損検出用のキヤツ
プ７が被冠されるが、上記キヤツプ７には空気管
５およびサンプリング管６が取り付けられてい
る。上記空気管５の一端部は原子炉容器１０外に
あるブロワー１５に開閉弁１６を介して連接され
ており、さらに上記開閉弁１６のキヤツプ７側に
は空気放出弁１７が設けられている。一方、サン
プリング管６には原子炉容器１０の外方において
開閉弁１８を介してサンプリングポンプ１９が設
けられ、さらにその先端部にサンプリング容器２
０が配設されている。 Incidentally, a cap 7 for detecting fuel damage is sequentially attached to any one of the many fuel assemblies that make up the reactor core 11, and an air pipe 5 and a sampling pipe 6 are attached to the cap 7. There is. One end of the air pipe 5 is connected to a blower 15 outside the reactor vessel 10 via an on-off valve 16, and an air release valve 17 is provided on the cap 7 side of the on-off valve 16. On the other hand, a sampling pump 19 is provided on the outside of the reactor vessel 10 in the sampling pipe 6 via an on-off valve 18, and a sampling pump 19 is provided at the tip of the sampling pump 19.
0 is placed.
しかして、燃料破損の検出に際しては、従来と
同様に点検しようとする燃料集合体１の頂部にキ
ヤツプ７をかぶせ、空気放出弁１７を閉じるとと
もに開閉弁１６を開け、ブロワー１５によつてキ
ヤツプ７内に空気を送る。すると、上記燃料集合
体１の上部とキヤツプ７内に空気層８が形成され
て、燃料集合体１内上部に液面９が形成され、燃
料集合体１内への流入が停止する。 When detecting fuel damage, the cap 7 is placed over the top of the fuel assembly 1 to be inspected in the same manner as in the past, the air release valve 17 is closed, the on-off valve 16 is opened, and the blower 15 is used to close the cap 7. Send air inside. Then, an air layer 8 is formed in the upper part of the fuel assembly 1 and in the cap 7, a liquid level 9 is formed in the upper part of the fuel assembly 1, and the flow into the fuel assembly 1 is stopped.
そこで、この状態で一定時間放置する。しかし
て、上記燃料集合体１内に滞留している冷却材は
その温度が上昇し、燃料集合体１の下部にはプレ
ナム２１の冷却材との温度差によつて温度境界層
２２が形成される。第４図はこのときの燃料集合
体の軸線方向の温度分布の時間変化を概略的に示
したもので、冷却材の流れを停止した時間をt0か
ら順次t1、t2…と長くすると、燃料集合体１の下
部では時間の経過とともに温度勾配の急な温度境
界層ができる。しかも燃料集合体の冷却材は、燃
料棒の崩壊熱により加熱され、プレナム２１の冷
却材より軽くなるため上記温度境界層は安定なも
のとなり、その結果核分裂生成物の溶け込んだ燃
料集合体内の冷却材のプレナム２１側への拡散は
殆どなくなる。 Therefore, leave it in this state for a certain period of time. As a result, the temperature of the coolant staying in the fuel assembly 1 rises, and a temperature boundary layer 22 is formed in the lower part of the fuel assembly 1 due to the temperature difference with the coolant in the plenum 21. Ru. Figure 4 schematically shows the temporal change in the temperature distribution in the axial direction of the fuel assembly at this time, and as the time during which the flow of coolant is stopped is increased sequentially from t 0 to t 1 , t 2 , etc. , a temperature boundary layer with a steep temperature gradient is formed in the lower part of the fuel assembly 1 over time. Moreover, the coolant in the fuel assembly is heated by the decay heat of the fuel rods and becomes lighter than the coolant in the plenum 21, so the temperature boundary layer becomes stable, resulting in cooling of the fuel assembly in which the fission products are dissolved. Diffusion of the material toward the plenum 21 side is almost eliminated.
また、燃料集合体１に流入する冷却材流れを一
定時間放置することによつて、その間核分裂生成
物が冷却材中に放出し続け、燃料集合体１内の冷
却材の自然対流によつて上記核分裂生成物の燃料
集合体内での拡散が生じ、かつ冷却材中の核分裂
生成物濃度が高められる。 In addition, by leaving the flow of coolant flowing into the fuel assembly 1 for a certain period of time, fission products continue to be released into the coolant during that time, and the natural convection of the coolant within the fuel assembly 1 causes the above-mentioned Diffusion of fission products within the fuel assembly occurs and the concentration of fission products in the coolant increases.
次に、上記温度境界層が安定状態となる一定時
間経過後ブロワー１５の駆動を止めて燃料集合体
１に供給していた空気を止めるとともに開閉弁１
６を閉じ、空気放出弁１７を開ける。しかして、
燃料集合体１の上部および空気管５内の空気が排
気され、これに応じて燃料集合体１内に残留熱除
去系から原子炉容器に供給されている冷却材がプ
レナム２２から流入しはじめる。したがつて、燃
料集合体１への冷却材供給再開以前に燃料集合体
１に滞留していた冷却材と新らたに燃料集合体１
に流入した冷却材の温度差による温度境界層２２
も燃料集合体１で上昇する（第５図および第６図
参照）。 Next, after a certain period of time has elapsed for the temperature boundary layer to reach a stable state, the drive of the blower 15 is stopped to stop the air being supplied to the fuel assembly 1, and at the same time, the on-off valve 1
6 and open the air release valve 17. However,
The air in the upper part of the fuel assembly 1 and in the air pipe 5 is exhausted, and in response, the coolant that is being supplied to the reactor vessel from the residual heat removal system begins to flow into the fuel assembly 1 from the plenum 22. Therefore, the coolant that had accumulated in the fuel assembly 1 before the resumption of coolant supply to the fuel assembly 1 and the new fuel assembly 1
Temperature boundary layer 22 due to temperature difference of coolant flowing into
also rises in the fuel assembly 1 (see FIGS. 5 and 6).
ところで、一般的に残留熱除去系により冷却材
が燃料集合体を流れる場合、燃料集合体内の冷却
材流速は約６〜12cm／ｓ程度しかない。したがつ
て、このような低流速においては前記温度境界層
２２が冷却材の流れによつて乱されることもな
く、その温度境界層の上部の冷却材、すなわち燃
料集合体１で一定時間滞在し核分裂生成物濃度が
高められた冷却材はピストン状に押し上げられ
る。そのため、前記核分裂生成物濃度が高められ
た冷却材層がピストン状に押し上げられて燃料集
合体から流出する時間（約１〜２分）だけ、冷却
材をサンプリング管６を介して採取し続けること
により、冷却材中に溶け込んだ核分裂生成物を捕
集することができる。 By the way, in general, when coolant flows through a fuel assembly using a residual heat removal system, the flow rate of the coolant within the fuel assembly is only about 6 to 12 cm/s. Therefore, at such a low flow rate, the temperature boundary layer 22 is not disturbed by the flow of the coolant, and the coolant above the temperature boundary layer, that is, the fuel assembly 1, remains for a certain period of time. The coolant, which has an increased concentration of fission products, is pushed up like a piston. Therefore, the coolant must be continuously sampled through the sampling pipe 6 for the time period (approximately 1 to 2 minutes) during which the coolant layer with increased fission product concentration is pushed up like a piston and flows out of the fuel assembly. This makes it possible to collect fission products dissolved in the coolant.
しかして、従来のように自然対流のみによつて
核分裂生成物が拡散してサンプリング管に到達す
るのを待つのではなく、冷却材の上方への移動に
よつて核分裂生成物を冷却材とともにサンプリン
グ管まで導くので、燃料集合体１の下部で燃料破
損が発生した場合においても、核分裂生成物の検
出を確実に行なうことができる。 Therefore, instead of waiting for the fission products to diffuse only by natural convection and reach the sampling tube as in the conventional method, the fission products are sampled together with the coolant by moving the coolant upward. Since the fission products are guided to the pipe, even if fuel damage occurs in the lower part of the fuel assembly 1, the fission products can be reliably detected.
こゝで採取する冷却材量或は採取時間は、サン
プリングポンプ１９の能力や開閉弁１８の調節に
より任意に選定可能であるが、前記燃料集合体に
滞留した核分裂生成物濃度が高められた冷却材が
燃料集合体からサンプリング管６から流出し始め
てから流出し終るまでの時間（１〜２分）だけ連
続的に採取することが望ましい。 The amount of coolant sampled here or the sample time can be arbitrarily selected by adjusting the capacity of the sampling pump 19 and the on-off valve 18. It is desirable to sample continuously for a period of time (1 to 2 minutes) from when the material starts flowing out from the fuel assembly through the sampling tube 6 until it finishes flowing out.
そのためには、サンプリング管６に流入する冷
却材の温度を測定し、燃料集合体１内に滞留して
核分裂生成物を含みかつ崩壊熱により加熱された
冷却材と、冷却材流れを再開したのちプレナム２
１から燃料集合体１に流入する冷却材との温度
差、すなわち温度境界層２２で生じる温度差を検
出してサンプリング時間を調整すればよい。 To do this, the temperature of the coolant flowing into the sampling tube 6 is measured, and the coolant that has accumulated in the fuel assembly 1, contains fission products, and is heated by decay heat, and then the coolant flow is restarted. Plenum 2
The sampling time may be adjusted by detecting the temperature difference between the coolant flowing into the fuel assembly 1 and the coolant flowing into the fuel assembly 1, that is, the temperature difference occurring in the temperature boundary layer 22.
一方、燃料集合体１への冷却材流入を停止した
のち、燃料集合体への冷却材の流入開始時の冷却
材駆動力としては、上述のように残留熱除去系ポ
ンプ１２の利用が好ましいが、燃料集合体１への
冷却流れを停止しているときに、燃料集合体１内
に滞留している冷却材が崩壊熱によつて加熱され
て周囲の冷却材温度より高くなつているため、こ
の温度差による自然対流力を利用して冷却材の移
動を行なわせるようにしてもよい。 On the other hand, as described above, it is preferable to use the residual heat removal system pump 12 as the coolant driving force when the coolant starts flowing into the fuel assembly after stopping the coolant flowing into the fuel assembly 1. , when the cooling flow to the fuel assembly 1 is stopped, the coolant remaining in the fuel assembly 1 is heated by decay heat and becomes higher than the surrounding coolant temperature. The coolant may be moved using natural convection force due to this temperature difference.
また、本発明における燃料破損検出方法をより
確実にするためには、燃料集合体への冷却材流れ
を停止させる前に、放射能汚染の少ない低バツク
グランドの冷却材を燃料集合体に注入することに
より、燃料集合体内の冷却材を清淨な冷却材と置
換することが効果的である。この場合、燃料集合
体に注入する置換用冷却材としては、淨化系によ
り洗淨されたものや別途用意された、放射能に汚
染されていない清淨水を用いるのが理想的ではあ
るが、必ずしも完全な清淨水を用いる必要はな
い。すなわち、検査を希望すべき破損規模のとき
予想される放出蓄積される放射能レベルに対して
相対的に放射能レベルが低いものであれば、原子
炉容器等に貯蔵されている冷却材の一部を用いて
もよい。 Furthermore, in order to make the fuel failure detection method of the present invention more reliable, a low background coolant with less radioactive contamination is injected into the fuel assembly before stopping the flow of coolant to the fuel assembly. Therefore, it is effective to replace the coolant in the fuel assembly with clean coolant. In this case, it would be ideal to use purified water that has been purified by a septic system or separately prepared clean water that is not contaminated with radioactivity as the replacement coolant injected into the fuel assembly. It is not necessary to use completely clean water. In other words, if the radioactivity level is relatively low compared to the radioactivity level expected to be released and accumulated when the scale of damage is such that inspection is desired, some of the coolant stored in the reactor vessel etc. may also be used.
以上説明したように、本発明においては原子炉
容器内に装架されている燃料集合体の頂端部を、
空気管およびサンプリング管を設けたキヤツプで
覆い、そのキヤツプ内に空気を封入することによ
つて燃料集合体の下方より流入し上方に流出する
冷却材流れを停止させ、その状態を一定時間保持
させた後燃料集合体上部の空気層を排除し、燃料
集合体内の冷却材流れを再開させ、燃料集合体内
に滞留していた冷却材を所定時間サンプリング
し、サンプリングした冷却材の放射能測定により
燃料棒の破損の有無を検出するようにしたので、
サンプリング作動時に核分裂生成物が溶け込んだ
冷却材がピストン状にそのまゝ順次押し上げられ
てサンプリング管に送入され、冷却材中に溶け込
んだ核分裂生成物を確実に捕集することができ、
しかも燃料集合体の下部で燃料破損が発生した場
合においても、核分裂生成物の検出を確実に且つ
短時間に行なうことができて、燃料破損検出の信
頼性を向上させることができる。
As explained above, in the present invention, the top end of the fuel assembly installed in the reactor vessel is
By covering the fuel assembly with a cap equipped with an air pipe and a sampling pipe and sealing air within the cap, the flow of coolant flowing from the bottom of the fuel assembly to the top is stopped and this state is maintained for a certain period of time. After that, the air layer above the fuel assembly is removed, the coolant flow within the fuel assembly is restarted, and the coolant that has remained inside the fuel assembly is sampled for a predetermined period of time, and the radioactivity of the sampled coolant is measured. Since it is possible to detect whether or not the rod is damaged,
During the sampling operation, the coolant with the fission products dissolved in it is pushed up in a piston-like manner and sent into the sampling tube, making it possible to reliably collect the fission products dissolved in the coolant.
Moreover, even if fuel damage occurs in the lower part of the fuel assembly, fission products can be detected reliably and in a short time, and the reliability of fuel damage detection can be improved.
第１図は沸騰水型原子炉における従来の燃料破
損検出方法の概略説明図、第２図は燃料破損検出
装置の概略構成図、第３図は本発明の燃料破損検
出方法の作動説明図、第４図は燃料集合体内の冷
却材の軸方向温度分布図、第５図および第６図は
それぞれ本発明方法実施中における冷却材の温度
境界層の変化説明図である。
１……燃料集合体、２……チヤンネルボツク
ス、３……燃料棒、５……空気管、６……サンプ
リング管、７……キヤツプ、１５……ブロワー、
１９……サンプリングポンプ。
FIG. 1 is a schematic explanatory diagram of a conventional fuel damage detection method in a boiling water reactor, FIG. 2 is a schematic configuration diagram of a fuel damage detection device, and FIG. 3 is an operation explanatory diagram of the fuel damage detection method of the present invention. FIG. 4 is an axial temperature distribution diagram of the coolant in the fuel assembly, and FIGS. 5 and 6 are diagrams each illustrating changes in the temperature boundary layer of the coolant during implementation of the method of the present invention. 1... Fuel assembly, 2... Channel box, 3... Fuel rod, 5... Air pipe, 6... Sampling tube, 7... Cap, 15... Blower,
19...Sampling pump.
Claims (1)
頂端部を、空気管およびサンプリング管を設けた
キヤツプで覆い、そのキヤツプ内に空気を封入す
ることによつて燃料集合体の下方より流入して上
方に流出する冷却材流れを停止させ、その状態を
一定時間保持させた後燃料集合体上部の空気層を
排除し、燃料集合体内の冷却材流れを再開させ、
燃料集合体内に滞留していた冷却材を所定時間サ
ンプリングし、サンプリングした冷却材の放射能
測定により燃料棒の破損の有無を検出するように
したことを特徴とする、燃料破損検出方法。 ２ 燃料集合体下部に滞留した冷却材が、サンプ
リング管に流入するまでの間、サンプリングを行
なうことを特徴とする、特許請求の範囲第１項記
載の燃料破損検出方法。 ３ 燃料集合体内に滞留し温度上昇した冷却材
と、冷却流れを再開した後におけるプレナムから
燃料集合体内に流入した冷却材との温度差によつ
て、サンプリング終了時間が制御されることを特
徴とする、特許請求の範囲第１項記載の燃料破損
検出方法。 ４ 燃料集合体内に滞留せしめる冷却材は、放射
能汚染の少ない冷却材と置換させることを特徴と
する、特許請求の範囲第１項記載の燃料破損検出
方法。 ５ 燃料集合体内に滞留した冷却材は、強制循環
によつてサンプリング管側に移送されることを特
徴とする、特許請求の範囲第１項乃至第４項のい
ずれかに記載の燃料破損検出方法。[Claims] 1. Covering the top end of a fuel assembly installed in a reactor vessel with a cap provided with an air pipe and a sampling pipe, and sealing air in the cap to supply fuel. The flow of coolant flowing in from the bottom of the fuel assembly and flowing out upward is stopped, and after this state is maintained for a certain period of time, the air layer above the fuel assembly is removed, and the flow of coolant within the fuel assembly is restarted.
A method for detecting fuel damage, characterized in that the presence or absence of damage to a fuel rod is detected by sampling the coolant stagnant in a fuel assembly for a predetermined period of time and measuring the radioactivity of the sampled coolant. 2. The method for detecting fuel damage according to claim 1, characterized in that sampling is performed until the coolant accumulated in the lower part of the fuel assembly flows into the sampling pipe. 3. The sampling end time is controlled by the temperature difference between the coolant that has remained in the fuel assembly and has increased in temperature, and the coolant that has flowed into the fuel assembly from the plenum after restarting the cooling flow. A method for detecting fuel damage according to claim 1. 4. The method for detecting fuel damage according to claim 1, characterized in that the coolant retained in the fuel assembly is replaced with a coolant with less radioactive contamination. 5. The fuel damage detection method according to any one of claims 1 to 4, characterized in that the coolant accumulated in the fuel assembly is transferred to the sampling pipe side by forced circulation. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58016564A JPS59150389A (en) | 1983-02-03 | 1983-02-03 | Method of detecting fuel failure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58016564A JPS59150389A (en) | 1983-02-03 | 1983-02-03 | Method of detecting fuel failure |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59150389A JPS59150389A (en) | 1984-08-28 |
| JPH0363719B2 true JPH0363719B2 (en) | 1991-10-02 |
Family
ID=11919774
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58016564A Granted JPS59150389A (en) | 1983-02-03 | 1983-02-03 | Method of detecting fuel failure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59150389A (en) |
-
1983
- 1983-02-03 JP JP58016564A patent/JPS59150389A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59150389A (en) | 1984-08-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4034599A (en) | Device for locating defective fuel | |
| US4072559A (en) | Method and apparatus for the zone-wise shuffling of nuclear reactor fuel elements | |
| US5414742A (en) | Leak-detection system and method for detecting a leaking container | |
| US9773575B2 (en) | Passive filtration of air egressing from nuclear containment | |
| US4147587A (en) | Method for detecting the failure of nuclear fuel elements | |
| US3419467A (en) | Method of and apparatus for locating envelope-tube damage at individual nuclear fuel elements in a reactor core | |
| US4696788A (en) | Process and device for detecting defective cladding sheaths in a nuclear fuel assembly | |
| CN85109072A (en) | The method and apparatus that cladding defect detects in the nuclear fuel assembly | |
| KR102372548B1 (en) | Analytical device for detecting fission products by measurement of radioactivity | |
| JPH0363719B2 (en) | ||
| US4204911A (en) | Method and apparatus for removing iodine from a nuclear reactor coolant | |
| JPH0473120B2 (en) | ||
| KR101893550B1 (en) | Apparatus for preventing radiation exposure of an inspection apparatus of a calandria | |
| JPS6063496A (en) | Method of detecting damage of fuel | |
| JPH0439636B2 (en) | ||
| JPH047478B2 (en) | ||
| US20250266179A1 (en) | Method and Apparatus to Test for Defects in Irradiated Nuclear Fuel | |
| JPS6111699A (en) | Detector for damage of fuel for nuclear reactor | |
| KR102657102B1 (en) | Open-type reactor coolant collection and cooling device for nuclear power plants equipped with an in-containment refueling water storage tank and its relevant method | |
| KR20180082990A (en) | Apparatus for preventing radiation exposure of an inspection apparatus of a calandria | |
| JPS6177797A (en) | Fuel damage detector | |
| RU2234753C1 (en) | Nuclear power reactor shutdown process | |
| JP3900338B2 (en) | Radioactive noble gas recovery method | |
| Kessler et al. | STORAGE OF DEPLETED AVR SPHERICAL FUEL ELEMENTS IN THE SPENT FUEL PIT OF THE HOT CELLS AT JOLICH | |
| KR820000833B1 (en) | Crack detection ceil for checking the leak prootness of fuel element units |