Given only 'dateline karen read story', Karen's identity remains a mystery. She might be a staff member at Dateline who was reading a story for work purposes. Or she could be a person who was interviewed by Dateline and was reading a story during the interview, or she could be an ordinary person whose story - reading experience is being highlighted in relation to Dateline.
It's hard to say for sure. 'Karen' could be a blend of real incidents and creative imagination. Sometimes, such stories take real-life inspirations but are embellished for entertainment value.
The Karen Silkwood story is indeed true. It was a significant incident that raised awareness about workplace safety and corporate responsibility. There's a lot of documented evidence to support the events that occurred.