Tokyo Electric Power Co. said Friday that 1,973 workers at the Fukushima No. 1 nuclear plant have estimated thyroid radiation doses exceeding 100 millisieverts and are therefore at higher risk of getting thyroid cancer.

The workers will be allowed to undergo annual ultrasonic thyroid examinations free of charge, the utility said.

Tepco has given health checks to 19,592 workers — 3,290 Tepco employees and 16,302 employees of its partner firms.