12m 18s: Lenght

ambient radiation on a path 0.09μSv/h ambient radiation on the spot (1 meter) 0.12μSv/h ambient radiation on the spot (50cm) 0.26μSv/h surface of the spot 0.47μSv/h location↓ https://www.google.co.jp/maps/place/35%C2%B046'05.7%22N+139%C2%B049'31.8%22E/@35.768343,139.8254421,21z/data=!4m7!1m4!3m3!1s0x0:0x0!2zMzXCsDQ2JzEyLjkiTiAxMznCsDQ5JzI5LjYiRQ!3b1!3m1!1s0x60188fc641c5fc39:0x7d912e650d6e464f?hl=ja