Original: Other serious nuclear and radiation accidents include the Mayak disaster , Soviet submarine K-431 accident , Soviet submarine K-19 accident , Three Mile Island accident , Costa Rica radiotherapy accident , Zaragoza radiotherapy accident , Goiania accident , Windscale fire , Church Rock Uranium Mill Spill and the SL-1 accident .
Simplified: Other serious nuclear accidents include Three Mile Island , the Windscale fire , the Mayak accident , and the SL-1 accident .