Steam is rising from a destroyed building that houses a reactor at Japan’s crippled Fukushima Daiichi nuclear power plant, the operator of the plant, Tokyo Electric Power Co, said on Thursday.
The utility, widely known as Tepco, said the levels of radioactivity around the plant had remained unchanged and it was still looking into what triggered the emission.
“We think it’s possible that rain made its way through the reactor building and having fallen on the primary containment vessel, which is hot, evaporated creating steam,” said Tepco spokeswoman Maymi Yoshida, adding it was still investigating the matter.
Each reactor is surrounded by a primary containment vessel. This is made of strengthened steel four to eight inches thick. It provides the most critical line of defense against leaking radiation from the reactor.
The steam rising from the reactor No.3 building was spotted at 8:20 a.m. local time (7:20 p.m. ET Wednesday) by a subcontractor who was filming the destroyed building and preparing to remove rubble from the site. It was still visible some two hours later, Yoshida said.