3）-3.Challenges and controversies of protecting the environment from ionizing radiation

New channel OCW Tsukuba: title sample judged 'whole' (This is an official university OpenCourseWare channel with nearly all uploads being full lectures, courses, or clinical/); passed a second screen for sellers/exam-prep/re-uploads; 0 of 3 sampled transcripts showed teaching, 0 not; titles picked one by one, checked strictly; oEmbed verified.