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In this photo from a footage of a live camera released by Tokyo Electric Power Co. (TEPCO), black smoke billows from the crippled Fukushima No. 1 Nuclear Power Plant in Okumamachi, northeastern Japan, on March 22, 2011. (AP Photo)

As the Fukushima nuclear crisis rages on, the government's Nuclear Safety Commission (NSC) has decided to revise design safety screening guidelines for nuclear reactors to help avoid long-term losses of electricity at nuclear power plants.

The Fukushima crisis began when power was knocked out to the plant's cooling systems. However, current design safety screening guidelines stipulate that "There is no need to consider" a long-term loss of electricity from external sources or emergency diesel power generators.

The NSC is expected to start revising the guidelines without waiting for the outcome of the government's investigation into the Fukushima crisis.

When utility firms build nuclear power plants, they are required to file applications with the central government for permission, which in turn are to be screened by the government and the NSC. The NSC drew up the current 59-point "design safety screening guidelines" document in 1990, which states, "There is no need to consider a response to a long-term loss of electric power, as resumption of transmission and repairs to emergency power generators can be anticipated."

The NSC will start revising the guidelines as early as next month, and will include points to cope with a possible long-term loss of power. It will be the first revision to the guidelines since 2001, when they were amended slightly.

Apart from the guidelines, under the instructions of Economy, Trade and Industry Minister Banri Kaieda, the ministry has been working on emergency safety measures including one which calls for all nuclear power plants across the country to be equipped with multiple emergency power generators. At the Fukushima No. 1 Nuclear Power Plant, electrical pylons fell over, disrupting power supply from outside.

Of the total 13 emergency diesel power generators installed at the Nos. 1, 2, 3, 4, 5 and 6 reactors at the Fukushima plant, 12 malfunctioned due to tsunami and almost all sources of power were lost at once. The reactor cores and spent nuclear fuel pools could not be cooled while work was underway to restore power, and as a result massive amounts of radioactive substances were leaked.