By Chris Hogg
BBC News, Tokyo
There are fears the closure of Kashiwazaki may lead to blackouts
Japan's trade minister has given the power companies that run the country's nuclear facilities a week to put in place better safety procedures.
Minister Akira Amari said he also plans to ask the country's businesses to save power this summer to try to reduce demand at peak times.
An earthquake on Monday damaged the world's largest power station.
The Kashiwazaki-Kariwa plant supplies around 10% of the output of the power company, Tokyo Electric Power.
The facility remains closed.
Japan's trade minister summoned representatives of the 11 firms involved in nuclear power generation in Japan for what were called emergency talks.
He gave them six days to demonstrate that they have tightened up safety procedures.
In particular, he wants firefighters stationed at each nuclear power station.
He also wants assurances that accurate information about any accident at a plant is passed swiftly to the government.
These are the lessons learnt after Monday's quake started a fire and led to radioactive leaks from the Kashiwazaki-Kariwa facility.
The government was not told about the leaks for seven hours.
The minister said he had been assured that there would not be shortages of power this summer as long as temperatures in Japan remained at average levels for the time of year.
He told the power companies though that as the weather was unpredictable he would be asking industry to conserve energy during periods of peak demand.
Restrictions would be needed to ensure continuity of supply. It is not clear yet though what this might mean in practice.