TOKYO, Japan — The families of senior executives from Tokyo Electric Power Co. — operator of the stricken Fukushima nuclear plant — are under 24-hour police guard after their home addresses were posted online.

There has been growing anger at the company, known as TEPCO, which has a history of safety mishaps and cover-ups, over prolonged radiation releases since the March 11 tsunami knocked out cooling systems at the Fukushima Daiichi facility.

At the house of TEPCO Chairman Tsunehisa Katsumata, in the Shinjuku district of central Tokyo, concrete and steel barriers have been erected at the building's entrance, while a policeman stands guard in front of a temporary police post that has been set up there.

“We decided to station officers there because of the danger to his family, as their address and threats have been posted on the internet,” said a senior officer at the nearby Yotsuya Police Station, who asked not to be identified by name. “The chairman is currently staying at the TEPCO headquarters but the family is still here.”

The addresses of TEPCO’s president, chairman and six other senior executives were posted on a website titled the “Association of TEPCO Victims,” which encourages citizens to sue the company over the radiation leaks that occurred at the Fukushima nuclear plant. The leaks have led to mass evacuations and enormous damage to the surrounding farming and fishing industries.

Japan has been pumping radioactive water, used to cool down overheated fuel rods, into the sea for the past five days due to a lack of storage space. A TEPCO official said late Friday that the pumping would stop on Saturday.

But damage has been done. The plant has already released massive amounts of radiation. China has detected 10 shipments arriving from Japan with higher than normal levels of radiation since mid-March, and radiation from the Fukushima disaster has been detected as far afield as Idaho.

With so many people scared and looking for a place to direct their anger, authorities fear for the safety of the TEPCO president and executives whose addresses were posted to the internet. Although the website that published the addresses advocates legal action against the utility’s management, it links to message boards suggesting more direct methods.

The Ni-Channeru (2 Channel) boards, which contain thousands of anti-TEPCO messages across hundreds of threads, are notorious for the vitriolic nature of their contents. The anonymous nature of the postings on Ni-Channeru facilitates a rare opportunity for unrestricted venting in what remains a society still largely characterized by self-control and etiquette.

The “Ways to Execute TEPCO Executives” thread contains more than 500 posts discussing suitable fates for the company’s management, as well as direct threats against them and their families. These include, “The execution of TEPCO is the will of the nation’s citizens,” “Shimizu [the company president who was hospitalized with stress during the crisis] should take his own life to apologize for what’s happened. If he can’t do this, I’ll find the address of his family…” and “I thought there could be no worse criminal organization that the Aum Shinrikyo [the religious cult which carried out a deadly Sarin gas attack on the Tokyo subway in 1995] but now there is TEPCO.”

Posts in other threads state, “If there are deformed babies born in the future, it will be TEPCO’s fault” and “This island will soon be uninhabitable, and it’s all down to TEPCO.”

The mounting anger at TEPCO has been exacerbated by the fact that the company has a track record of accidents and deceit that stretches back decades.

In the 1980s TEPCO falsified reports on cooling systems at two nuclear facilities, the truth only emerging in 2006.

In 2003, TEPCO was forced to temporarily cease operations at all its nuclear plants after a scandal over falsified inspection data on its safety procedures led to the resignation of four executives.

Then in 2007, when a 6.8-magnitude earthquake damaged the Kashiwazaki-Kariwa plant — the world’s largest nuclear power station — TEPCO was heavily criticized for hiding the full extent of the potential danger of the situation, and that radiated water had leaked into the ocean.

The fact that such a large nuclear facility was built so close to a seismic fault line in the first place was described by a leading Tokyo-based TEPCO analyst as “nothing short of ridiculous.”

The president of TEPCO at the time was the current chairman Katsumata, who was forced to step down due to the scandal and his poor handling of it. His role as chairman was intended to be largely honorary. However, when his successor as president, Masataka Shimizu, disappeared from the public eye at the height of the crisis, apparently suffering from stress, Katsumata was forced to once again take the reins at the company. Unsurprisingly, his face was not one that many Japanese people wanted to see.

Prior to the current nuclear crisis, TEPCO was one of the world’s largest private utility companies, worth more than $40 billion — its share price has crashed over 80 percent since. It was also embarking on a major overseas expansion drive, attempting to export its nuclear technology to Asia and the Middle East, as well as acting as a consultant on a nuclear project in Texas.

While successfully solving the Fukushima crisis is of course the most pressing matter, whether it can survive as a corporate entity, is already being discussed — its nationalization has been mulled.

For now, Prime Minister Naoto Kan is insisting it prepare a 1 trillion yen ($11.7 billion) fund to pay for the clean-up of Fukushima and compensation for the tens of thousands of lives that will continue to be blighted for many years to come.