Photo/Illutration Upper House members attend a plenary meeting on May 31 where a bill was enacted to allow nuclear reactors to operate beyond 60 years. (Koichi Ueda)

A controversial bill that will allow aging nuclear reactors to stay online past 60 years was passed by the Diet with the approval at the Upper House on May 31.

Reactors can operate beyond that period as times they are shut down for safety inspections or court injunctions will now be excluded from their service time calculation with the passing of the bill.

In principle, the Law on the Regulation of Nuclear Reactors limits nuclear reactors’ operational periods to 40 years. However, it also says that the period can be extended for up to 20 years if the Nuclear Regulation Authority sanctions it.

The limit was introduced after the triple meltdown at the Fukushima No. 1 nuclear power plant in 2011, with the support of the Liberal Democratic Party and Komeito, which were opposition parties at the time.  

The bill on decarbonization of energy sources revises five laws, including the Law on the Regulation of Nuclear Reactors, the Electricity Business Law and the Atomic Energy Basic Law.

With the revisions, the rule about nuclear reactors’ operational periods will be removed from the Law on the Regulation of Nuclear Reactors, which is under the NRA’s jurisdiction.

It will instead be added to the Electricity Business Law, which falls under the industry ministry’s jurisdiction.

The revisions also mean that when counting nuclear reactors’ operational periods, the time during which nuclear reactors are shut down for safety inspections by the NRA, court-ordered injunctions or administrative guidance will be excluded from the calculation.

If an electricity company requests the operational period of its nuclear reactor be extended, an industry minister will assess the proposal on whether the extension will contribute to the stable supply of electricity or decarbonization, or whether the utility made a voluntary effort to improve the reactor safety.

The NRA will continue to be responsible for ensuring the safety of nuclear reactors.

It will assess the degradation of nuclear reactors every 10 years or earlier once they have been in service for 30 years.

The periods in which nuclear reactors are shut down will be included when counting the reactors’ operational period toward the 30-year starting point of the assessment.

One of the five laws that the new legislation revises is the Atomic Energy Basic Law, which is called “the constitution of nuclear power.”

The revised law defines taking measures necessary to utilize nuclear reactors for a stable power supply or decarbonization as “the responsibility of the state.”