Japan's Nuclear Regulation Authority has delayed a decision on whether to approve a plan to extend the operating period of power plants, after one of its members opposed the proposal.

The nuclear plant service period in Japan is now 40 years in principle. It can be extended by another 20 years if approved by the NRA. The government's policy shift enables plants to remain operational beyond the 60-year cap, excluding the time spent undergoing inspections and testing.

The NRA has come up with a system for dealing with the aging of nuclear power plants. It proposes that after a plant has been in operation for 30 years, its equipment and devices should be checked for deterioration every 10 years or less, and management plans should be drawn up each time.

The NRA discussed whether to finalize the draft plan at a regular meeting on Wednesday.

Ishiwatari Akira, a member in charge of earthquake and tsunami assessment, opposed the proposal based on the fact that the jurisdiction regarding the operation period restriction will be transferred from the NRA to the industry ministry.

He said it is the NRA's mission to protect people and the environment based on its knowledge of science and technology. He stressed that scrapping the limit on the plant service period cannot be considered a change that would improve safety.

Ishiwatari pointed out that the plan allows the operation period to be extended by the amount of time it has taken to carry out inspections. He said this means that the more time it takes to conduct inspections, the older the plants will get.

The NRA plans to discuss the proposed system again next week.

At the meeting, comments from the public on the draft system were also introduced. The feedback was solicited for 30 days by January 20. A total of 1,749 comments were received.

Many of them were against the plan. One said the lifespan of reactors has been limited to 40 years following the Fukushima Daiichi nuclear accident, and the cap must be observed. Another said there is a limit to what inspections and evaluations can do.

In response, the NRA said the degree of deterioration of reactor facilities depends on how they are used or managed. The regulator said it is necessary to assess deterioration at an appropriate timing and confirm whether the reactors are up to standard.