報告書番号

209

タイトル（和文）

軽水型原子炉環境における鉄鋼材料の脆化に関する研究

タイトル（英文）

STUDY ON ENVIRONMENT-INDUCED EMBRITTLEMENT OF STEELS FOR LIGHT WATER REACTOR

概要 （図表や脚注は「報告書全文」に掲載しております）

軽水型原子炉環境中における鉄鋼材料の脆化に関して，当所で実施して来た研究を総括した。（１）現用軽水炉圧力容器鋼のＡ５３３Ｂ鋼の照射脆下は微量の銅，Ｐ，Ｓ，およびＶの含有によって促進され，銅およびＰ含有に起因する加速照射脆化は微量のチタンまたはＡ１の添加によって改善される。（２）非照射の圧力容器鋼の水素脆化挙動として，微量の水素吸収（０．５～５ｐｐｍ）に対して最も敏感な性質は伸びおよび絞りのような延性である。（３）原子炉圧力容器鋼の機械性質と破壊モードは照射欠陥と水素原子の相互作用によって合理的に説明できる。（４）高温純水中ＳＣＣ感受性評価技法および表面加工処理効果と窒素添加ステンレス鍜鋼の高温純水中ＳＣＣ感受性を評価下。（５）鋭敏化ステンレス鋼のＳＣＣ感受性は速中性子照射によって若干増大する傾向を示す。

概要 （英文）

(1)THE EMBRITTLEMENT OF NEUTRON-IRRADIATED A533B STEELS IS ACCELERATED BY CONTAINING A SMALL AMOUNT OF COPPER,PHOSPHORUS,SULFUR AND VANADIUM.THE ADDITION OF TITANIUM AND ALUMINIUM IS FOUND TO BE EFFECTIVE IN THE IMPROVEMENT OF THE NEUTRON IRRADIATION-ENHANCED EMBRITTLEMENT OF A533B STEELS CONTAINING COPPER AND PHOSPHORUS.(2)HYDROGEN-INDUCED EMBRITTLEMENT OF NEUTRON UNIRRADIATED STEELS FOR LWR PRESSURE VESSLE IS INVESTIGATED.AMONG MANY MECHNICAL PROPERTIES,DUCTILITY IS FOUND TO BE MOST SENSITIVE TO ABSORPTION OF A SMALL AMOUNT OF HYDROGEN(0.5-5PPM)(3)COMBINED EFFECTS OF NEUTRONIRRADIATION AND HYDOROGEN ABSORPTION ON MECHANICAL PROPERTIES OF LWR PRESSURE VESSEL STEELS ARE INVESTIGATED.MECHANICAL PROPERTIES AND FRACTUREMODES OF ABOVE MATERIALS CANBE REASONABLY EXPLAINED BY INTERACTIONS OF NEUTRON IRRADIATION-INDUCEDDEFECTS ANDHYDROGEN ATOMS.FROM A ENGINEERING STAND POINT,COMBINED EFFECTS OF NEUTRON IRRADIATION AND HYDROGEN ABSORPTION ON EMBRITTLEMENT OF REACTOR-USED VESSEL STEELS ARE NOT REMARKABLE.(4)SCC SUSCEPTIBILITY OF AUSTENITIC STAINLESS IS INVEATINGATED IN HIGHTEMPERATURE WATER.EVALUATION TECHNIQUES OF SCC SUSCEPTIBILITY AS FOLLOWS;DEVELOPMENT OF A NEW CONSTANT STRAIN SCC TESTING METHOD,DEPENDENCY OF STRESSWAVEFORM PARAMETERSUPON SCC SUSCEPTIBILITY UNDER CYCLIC TENSION METHOD AND SCC SUSCEPTIBILITY OF CONSTANT EXTENTION RATE TEST.THE OPTIMUM SHOT-PEENING CONDITIONS TO SUPPRESS THE SCC OCCURRENCE ARE FOUND.FORGED 316 LN AND 304LN STAINLESS STEELS WITH THE CARBON SUPPRESSED LESS THAN APPROX. 0.02% ARE FOUND TO BE PROMISING ALTERNATE MATERIALS HAVING EXACELLENT SCC RESISTANCE.(5)COMBINED EFFECTS OF NEUTRON IRRADIATION AND STRESS CORROSION OF AUSTENITIC STAINLESS STEELS AREINVESTIGATED. FOR THE SENDITIZED STAINLESS STEELS,A LITTLE INCREASE OF SCC OCCURRENCE DUE TO NEUTRON IRRADIATION IS FOUND IN THE INTERGRANULAR ST

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