報告書番号

380031

タイトル（和文）

地下式原子力発電所の想定事故時における放射性よう素および希ガスの地中格納効果

タイトル（英文）

UNDERGROUND CONTAINMENT OF RADIOACTIVE IODINE AND NOBLE GASES IN A HYPOTHETICAL ACCIDENT AT UNDERGROUND NUCLEAR POWER PLANT

概要 （図表や脚注は「報告書全文」に掲載しております）

地下式原子力発電所の事故時における安全性を評価するために，ガス状放射性よう素の砂岩および花崗岩の粉砕岩に対する吸・脱着の室内試験結果より，実地盤の吸・脱着特性を推定した。実地盤の吸・脱着特性は岩種とよう素の化学形態の組合せにより大きく異なることがわかった。発電所地下空洞から地表までの被りを２００ｍとした地盤モデルについて，地中格納効果の解析を行った。この結果，格納容器からの放出量に対する地表への漏洩量は，前述のよう素の吸・脱着物性値では１０の４８乗分の１程度であり，地盤中の固相への吸・脱着が期待できない希ガスでは１０の８乗分の１程度であった。この結果は地下式原子力発電所の事故時の安全性評価に役立つ。

概要 （英文）

UNDERGROUND SITING OF NUCLEAR POWER PLANT ISONE OF EFFECTIVE MEANS TO SOLVE THE MANY PROBLEMS ON THE SITING FROM THE ENGINEERING STANDPOINT.THE UNDERGROUND CONTAINMENT OF RADIOACTIVE FISSION PRODUCTS AT THE HYPOTHETICAL ACCIDENT IS PARTICULARLY EXPECTED ONTHE SEFETY MEASURES. THE CHARACTERISTIC VALUES OF ROCK MASS ON THE ABSORPTION AND THE ADSORPTION OF GASEOUS RADIOACTIVE IODINE WERE ESTIMATEDFROM THE RESULT OF THE LABORATORY TEST FOR THE CRUSHED SAND STONE AND THE CRUSHED GRANITE TO EVALUATE THE SAFETY IN THE ACCIDENT AT UNDERGROUND NUCLEAR POWER PLANT. THESE CHARACTERISTIC VALUES VARY ACCORDING TO THE COMBINATION OF THE KIND OF ROCK AND THE CHEMICAL FROM ON IODINE. THEUNDERGROUND CONTAINMENT OF THE GROUND MODEL OF WHICH THE THICKNESS OF EARTH COVERING ABOVE THE UNDERGROUND CAVITY IS 200M WAS ANALYZED. IT CAN BE SAID FROM THE RESULTS OF THE ANALYSIS THAT THE LEAKAGE FROM THE CONTAINMENT VESSEL OF IODINES WITH THE ABOVE CHARACTERISTIC VALUES DECREASES DOWN TO ABOUT TEN TO THE MINUS FORTY-EIGHT TO TEN TO THE MINUS SIXTY-FIVE AS LOW AS THAT IN THE ATMOSPHERE. ON THE OTHER HAND, IT CAN BE SAID FROM THE RESULTS OF THE ANALYSIS THAT THE LEAKAGE FROM THE CONTAINMENT VESSEL OF NOBLE GASES OF WHICH ADSORPTION ON SOLID PHASE IN THE GROUND CANNOT BE EXPECTED DECREASES DOWN TO ABOUT TEN TO THE EIGHT AS LOW AS THAT IN THE ATMOSPHERE.

報告者

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