BCの中性子照射効果とその回復挙動
Neutron irradiation effects on BC and recovery by annealing
堂野前 貴子 ; 舘 義昭 ; 関根 学*; 諸橋 裕子 ; 赤坂 尚昭; 小野瀬 庄二
Donomae, Takako; Tachi, Yoshiaki; Sekine, Manabu*; Morohashi, Yuko; Akasaka, Naoaki; Onose, Shoji
高速炉で効率的に核分裂生成物を核変換するためには減速材の利用が有効であり、BCはその候補の1つとされているが、BCの照射挙動は制御材用のBCと異なりほとんどデータが得られていない。そこで本論文では、高速炉で照射したBCペレットの外観・微細組織観察及び熱伝導率測定を行い、BCの照射挙動を明らかにした。照射BCの外観はBCと異なり、クラックは観察されなかったが、微細組織にはBCと同様に粒内及び粒界にバブルが確認された。BCの熱伝導率はBCよりも大きく、室温から1400Cの間には、BCと同様に3つの回復ステージが観察され、BCの回復とヘリウムの分散挙動の関連性が示された。以上から、BCペレットは照射下での安定性が高いことが確認され、減速材適用の可能性が示された。
Use of moderator materials in Fast Breeder Reactor (FBR) is effective for transmutation technology, and BC is one of the candidates. Up to now, the behavior of BC as the Control rod material is well known, but that of BC is hardly investigated. In this paper, the radiation effects of BC pellets, neutron irradiated in the experimental fast reactor JOYO were studied. From the experimental results, it was observed that no macro-cracks were recognized in the irradiated BC pellets. But, bubble nucleation was found in grain and along grain boundaries of BC. And, it was shown that the conductivity of BC was higher than that of BC. During the annealing from room temperature to 1400C, three recovery stages were found on thermal conductivity. It was suggested that, the recovery of BC was related to the dispersion behavior of helium. Judging from these results, as BC was mechanically more stable compared with BC under irradiation, it was shown that BC had high applicability for a moderator.