Operators of four nuclear plants in Japan are taking a step toward a goal that has been distant for a couple of years. They say they're preparing to apply for permission in July to restart reactors. Only one plant is online following the accident in Fukushima. Utility companies must meet new rules in order to fire up others. NHK World's Yoshiro Tateiwa explains. The four plants in question are dot across Japan from the south to the northern island of Hokkaido. Operators must prove reactors at the facilities adhered to new safety measures that come into effect in July. Nuclear regulators developed the guidelines in response to the 2011 accident at Fukushima Daiichi. Japan has 17 commercial nuclear plants. At one point all of them were offline because of the Fukushima crisis. Government leaders allowed the operator of the oil plant to restart two reactors last summer. They were concerned about the power shortages. Nearly a year later, the safety requirements facing the plant operators are even tougher. We hope to restart reactors as soon as their safety is confirmed. The new guidelines will force operators to prepare for severe accidents, including power outages and meltdowns. They must build a separate control room off site to serve as a backup facility. And they must install filters on vents used to release pressurized air in the reactors. That will limit the escape of radioactive substances during emergency. Operators will also be required to introduce tougher measures against tsunami. They will have to study the potential height of tsunami and build seawalls to withstand the largest waves. Officials at the Nuclear Regulatory Agency say there will set up three 20 member teams to screen applications. But some experts are concerned the system will not be effective. The new regulations cover severe accidents, which previous guidelines did not. The examiners have little knowledge of this area, so they will be learning and making difficult decisions as they go. That raises doubts about their expertise. Regulators say it will take six months to a year to complete the reviews. But the issue is not how long the work will take, but rather how effectively it will be done. You are a real Tatewa in the SK World.