通气式B_4C屏蔽棒的辐照考验

Irradiation test of ventilate B_4C shield rod

介绍了中国试验快堆屏蔽组件采用的通气式B4C屏蔽棒的结构与辐照考验结果。在BOP-60快中子反应堆对屏蔽棒的辐照考验表明：在508～580℃下，经383个有效辐照天后，最大快中子注量达0．38×10^23cm^-2（En〉0．1MeV），包壳材料的最大辐照损伤剂量为18．6dpa（原子离位次数），10^B平均燃耗约10．2％，最大燃耗约19．4％。屏蔽棒的结构完整，尺寸无明显变化，40个芯块中，有17个块保持原状和完整性，其余的损坏成两块或更多的小块，不可能从通气孔中逃逸，B4C芯块的最大肿胀值为△V／V≈4．2％。包壳的机械特性能保持足够高的水平，在最大损伤剂量部位的屈服强度增加了30％～40％，在500℃下屈服强度为760MPa。均匀伸长率在辐照后减少了25％～30％，在500℃下为1．4％。BaC吸收元件在达到的辐照参数下表现出高的辐照稳定性，可以用在CEFR反应堆的BaC屏蔽组件中。

This paper presents some irradiation test results of a ventilate B4 ℃ shield rod used in China Experimental Fast Reactor （CEFR） shield assembly. An irradiation test of ventilate B4℃ shield rod have been performed in Russian BOP-60 fast experimental reactor. After 383 effective radiation days at 508- 580 ℃, the maximum fast neutron influence reached 0.38× 10^23 cm^- 2 （En〉0.1 MeV）and the average and maximum 10^B burnup reached about 10.2% and 19.4% respectively. The irradiation damage dose of the cladding material （0Cr17Ni12Mo2Ti,20%C. W. ） approached 18. 6 dpa. Post-irradiation examinations indicated that： 1） The structure integrality of shield rod is keptand the size is not observably changed; 2） 17 out of 40 B4C pellets are integral and the rests breach into 2 fragments or more, but these fragments are big enough to escape from small ventilate hole; 3） The maximum irradiation swelling of B4C pellets is about 4.2%（AV/V） ; 4） The yield strength of cladding material increases by 30-40% and the elongation reduces by 25%-30%, they are 760 MPa and 1.4% respectively at 500 ℃ ; 5） The ventilate B4 C shield rod of CEFR presents good irradiation stability under reactor operation conditions and it is suited for CEFR shield assembly.