And residents never got the information

May 21, 2014

TEPCO ready to release radiation, not information, during Fukushima crisis

http://ajw.asahi.com/article/0311disaster/fukushima/AJ201405210045 

THE ASAHI SHIMBUN

In the chaotic early stages of the Fukushima nuclear disaster, Tokyo Electric Power Co. was preparing a last-ditch countermeasure that would have released a large amount of radiation on an unknowing public.

Masao Yoshida, the manager of the Fukushima No. 1 nuclear plant, told a government committee that dry venting was planned on March 14, 2011, to prevent rising pressure from causing the containment vessel of the No. 3 reactor to break apart, according to documents.

Venting is an emergency measure to prevent a containment vessel from rupturing and spewing huge amounts of radioactive materials into the atmosphere. But venting also results in the release of such substances, including radioactive iodine that can cause thyroid gland cancer, albeit at a lower level.

However, residents around the nuclear plant were never warned about the venting plan. At the time, the government had called on TEPCO and the Fukushima prefectural government not to make any announcements about the precarious situation at the No. 3 reactor to avoid panic among the public.

Under TEPCO’s manual to deal with nuclear accidents, the company is required to share as much information as possible with the central government and local municipalities about venting plans for possible evacuation and other emergency measures.

Dry venting was never carried out at the Fukushima plant, partly because an explosion at the No. 3 reactor building reduced pressure within the containment vessel. That explosion led to the release of radioactive materials, but the containment vessel remained largely intact.

Yoshida acknowledged the dry venting plan in testimony given to the government’s Investigation Committee on the Accident at the Fukushima Nuclear Power Stations. The Asahi Shimbun recently obtained a copy of Yoshida’s testimony.

In his exchanges with investigators, Yoshida described the crisis at the plant early on March 14, 2011, three days after the Great East Japan Earthquake and tsunami.

Water pumped in to cool nuclear fuel at the No. 3 reactor had dried up, and pressure was rising within the containment vessel.

TEPCO first attempted wet venting, in which steam containing gases that include radioactive materials is passed through water kept in the suppression chamber of the reactor. The measure can reduce the level of radioactive materials in the steam, but that effort failed at the Fukushima plant, according to the document.

At 6:23 a.m., TEPCO considered dry venting, a process that does not involve steam passing through water, at the No. 3 reactor, according to the document. Dry venting leads to the release of radioactive materials at concentrations between 100 and 1,000 times greater than through wet venting.

Shortly before 7 a.m., TEPCO conducted a simulation exercise related to dry venting, and later forecast radioactive iodine would be carried in a north-northwest direction by wind blowing from the south-southeast, the document showed.

Within three hours of dry venting, radiation levels near the district of Soma in northern Fukushima Prefecture were forecast to reach 250 millisieverts, more than double the 100-millisievert level used as a guideline for the ingesting of iodine tablets to prevent thyroid gland cancer, according to the document.

At 7:49 a.m., central government officials told TEPCO not to release information about the situation to the public. TEPCO officials later conducted another simulation about the spread of radioactive materials in the event of dry venting.

While TEPCO was still attempting wet venting, a hydrogen explosion at the No. 3 reactor building at 11:01 a.m. reduced the pressure in the containment vessel, eliminating the need for dry venting, according to Yoshida.

He told investigators he never knew about the media blackout concerning the No. 3 reactor.

Yoshida told the investigators, “Public relations officials can do whatever they want to, such as issuing press releases, but we at the plant had our hands full trying to deal with the accident.”

A TEPCO official told The Asahi Shimbun that the company had considered dry venting, but it did not make that information available to local residents.

The official simply said that when the company was studying the possibility of dry venting, it eventually became unnecessary to carry out the procedure.

Yoshida’s testimony underscores the confusion over who should inform residents about the possibility of dry venting. Such information would be vital for those concerned about possible radiation exposure who may be planning to flee the area.

As Yoshida’s testimony showed, informing the public may not be high on the list of priorities of workers trying to bring a nuclear accident under control.

Yoshida died of cancer last year.

Although more than three years have passed since the Fukushima nuclear accident started, no clear rules have been set on how to integrate measures dealing with a nuclear accident with the evacuation of local residents.

“Residents should be informed the minute consideration has begun on such an important decision as dry venting,” said Hideaki Kubori, a lawyer knowledgeable about corporate governance. “Companies have an obligation to protect the safety of residents during a serious incident.

“With the central government and TEPCO having failed to clarify responsibility even after three years, discussions should not begin on resuming operations at nuclear plants,” he said.

(This article was compiled from reports by Hideaki Kimura, Kyoko Horiuchi and Shinichi Sekine.)