About three dozen journalists sat on two buses. We wore protective suits, double gloves, double layers of clear plastic booties over shoes, hair covers, respirator masks, and carried radiation detectors. As we drove to the Fukushima plant, we passed through a police checkpoint, and saw three towns – Naraha, Tomioka, Okuma – empty of all inhabitants. Among the abandoned homes was a flower shop with plants, withered and dead, still on display.

As we approached the plant, radiation readings rose: 0.7 microsieverts per hour in Naraha, near the edge of the restricted zone. As we approached Okuma: 2.7ms. Then 4.1. It was rising quickly, the warning buzzer was going constantly. In Okuma, where it registered 6.7, the bus stopped so we could put on respirator masks. Every inch of our skin was now covered. We turned on to the road to the plant: 15ms. At the plant gate: 20. The buzzer became insistent.

The first things visible were six large cranes. Then we passed a field filled with blue tanks of contaminated water; then dozens of large, four-storey silver tanks of contaminated sea water. According to Tepco, which runs the plant, there are 90,000 tons of water stored here.

Next, there came a cluster of large white tents surrounded by black sand bags, and we got our first look at the damaged reactor buildings. No 1 was covered by new superstructure. No 2 was intact. No 3 was in worst shape: it was a skeletal concrete frame, collapsed into a pile of rubble. As we passed, three cranes were – and this is seven months since the tsunami – cleaning up rubble. No 4 was also severely damaged; the building was intact, but it was buckled, and the entire south side was blown out.

The reading here, about 500 metres from the reactors, was 50ms. The only signs of life were crows and dragonflies. Then we saw workers building water tanks, and, nearby, a rectangular concrete building used to store highly radioactive waste, including sludge. Workers in white hazmat suits busied about.

Next, we drove down to the reactors. As we drove through the pine forest (it looked bucolic, but isn't), we got our highest radiation reading of the trip: 1,000ms per hour.

At the base of the reactor buildings, there were crumpled trucks, contorted metal girders and frames of buildings, a huge storage tank dented and bent, and pipes twisted by the forces of nature. The damage reached up to the second storey, attesting to the tsunami's 14-metre size. A four metre-high sea wall has been built with rocks in black nets. Tepco said it was a makeshift defence against another tsunami. The reading here was 300ms.

The base of the reactor buildings was filled with debris and metal warped into fantastic shapes. We saw three white cars crushed together. Trucks had been hurled into empty pools. Office buildings smashed by the tsunami stood, slowly decaying, and along the waterfront was a pile of disassembled cranes, looking like a child's construction kit that had been abandoned mid-play.

We drove back up to the rest of plant, passing trucks with pumps which had been used in the early efforts to cool the boiling reactors. Soon, we reached reactors 5 and 6: these had been damaged by the tsunami, but less so. Their buildings were intact and clean.

Next, we were taken to the "seismic safety building", the plant's disaster headquarters. On the way, we saw evidence of the initial earthquake damage: big cracks in the earth and buckled metal shutters. On the roof of the disaster HQ were what had been small sheds, long since toppled.

And so we came to the disaster centre. Entering was a time-consuming process. In the first room, lined with pink plastic sheets, we were asked to take off our booties. We were directed into a second room where teams of workers cut off our protective suits with scissors. We took off our gloves, and masks. Inside was the roar of air filters. The radiation reading was about 1.5ms. On walls were long strings of paper cranes, posters and even hand towels with messages of support for plant workers from around Japan, and a few from United States.

I spoke to a Tepco spokesman, Tetsuya Terasawa. He said the temperature at the three damaged reactors is now below 100C, the target temperature. There was still 40,000 tons of water at the bottom of the reactor buildings, he said, adding that Tepco could not drain it because more water would flow in. They also have to be careful not to let the water build up, because the pressure could mean contaminated water leaking underground.

Tepco is pouring cooling water on to the three crippled reactors (1,2 and 3) to bring them to what's called cold shutdown. But the company recently admitted that if this process stops, the fuel will heat up again and nuclear fission is a possibility. Greenpeace and other anti-nuke groups think cold shutdown is industry spin. Tepco's strategy has left behind thousands of tons of contaminated water, which it is struggling to purify. Last month, to convince the public that the water is safe, a cabinet minister gulped down a glassful.

Next, we went into the response room, the plant's crisis centre. The large room was filled with men; no women work here. One wall was filled with screens showing live images from around plant; on another wall, was a small, plain wood Shinto shrine.

The nuclear crisis minister, Goshi Hosono, came to address the men here. "Every time I come back, I feel conditions have improved," he said. "This is due to your hard work." He said he is aiming for a cold shutdown by the end of the year. All good news, then? Not quite. There are still 30 years of work after that, he said, referring to the dismantling of the reactors.

The government says radiation is no longer spewing out of the plant at dangerous levels, but many people in Fukushima prefecture believe that radiation is sufficiently high to warrant evacuating many more people, especially children. Some observers want all two million people in the prefecture to be given the means to leave. Thousands of children in Fukushima city (population 700,000), more than 37 miles (60 km) from the plant, cannot play outside and must study in classrooms with closed windows. Many families have moved because they do not believe official pronouncements on the city's safety.

The plant chief, Masao Yoshida, said: "There is no doubt that the reactors have been stabilised, but that doesn't mean that it is extremely safe."

More than 80 per cent of Japan's 54 nuclear reactors, which provide about a third of the country's total energy needs, are offline, thanks to either the earthquake and tsunami or regular safety checks. By next spring, every one will be offline. Each one entails a political battle at the local level to restart, as local governments struggle to persuade a sceptical public that the sites are safe.