background radioactivity

常見(jiàn)例句

At the surface, radioactivity of the conglomerates is locally as high as 30 X background.
在地表，礫巖的局部地段的放射性高達(dá)30倍本底值。
The results showed that the radioactivity levels of each nuclide in Yangtze River water system were still lower than that of background, and did not cause contamination.
結(jié)果表明，各核素均未對(duì)長(zhǎng)江造成污染，長(zhǎng)江水系放射性濃度仍在本底水平。
The results show that the radioactivity level of varied water bod-ies of the city was within normal natural background.
調(diào)查結(jié)果表明，上海市各類(lèi)水體中天然放射性核素濃度屬正常本底水平。