back from them today. An anguished family. Thank you, bob woodruff. And next here tonight, an abc news investigation. Inside foulke sukushima. We want to know how bad the radiation is and ask if... See More
back from them today. An anguished family. Thank you, bob woodruff. And next here tonight, an abc news investigation. Inside foulke sukushima. We want to know how bad the radiation is and ask if they're doing all they can to keep it from coming to the united states. Cecilia vega takes us inside the hot zone. Reporter: This used to be a thriving community of farms and fishing villages. UNTIL MARCH 11th, 2011. Japan's largest earthquake ever. The tsunami that followed engulfed entire villages, flooding the fukushima daiichi power plant. And triggering a nuclear catastrophe. 2 1/2 years later, we gain rare access to examine the fallout by land and by sea, to find out if fukushima is still a threat to the rest of the world. Near the plant, a 12-mile stretch of evacuated land still teemed with radiation hot spots. Locals call it the no-go zone. We can go. On the other side, a ghost town, where time just stood still. This better work. We've been given rare access inside fukushima's ground zero to see the unprecedented cleanup underway. Though critics are skeptical the power plants embattled operator, tepco, is up to the task. The closer we get to the ruins of the meltdown, our radiation detectors climb. On another hot spot. It is a serious warning. Tepco told us we can only spend one hour inside the plant. Anymore time and we risk harmful radiation exposure. Radiation right here alone, about 2,000-times higher than outside fukushima. 1,500 highly-radioactive fuel roads in this pool. They have to move them out of reactor and to a safer location. Some say this is a first step to shut down this plant. A process that will take 40 years. And here's what tepco says it's doing to stop the radiation from entering the pacific. Under this concrete, there's a barrier. These steel tanks right here, another barrier. And the orange buoy over there is another barrier. Three right here to keep contaminated water from going into the ocean. Will you ever know how much contaminated water has made its way from the power plant into that ocean? Tepco's spokesman tells me, it's difficult to give an accurate number. So, we joined a team of scientists on the hunt for answers. What they say they find, radiation 1,000-times higher than before the melt down. Though, it's still below the legal limit for swimming and drinking. Can the damage that's been done be repaired here? Or is it too late? It's not too late, he says. But japan can't do it alone. We need help from the rest of the world. And they're not alone. We meet oceanographer and radiation expert ken bessler in fukushima. The japanese government claims radiation is contained in this small harbor outside the plant. But this team of scientists says they measured radiation linked to fukushima more than 70 miles aw away. Trace amounts have been found in bluefin tuna in california. But radiation dilutes as fish migrate to the u.S. I think the fear of what's happening outside the local area has been exaggerated. Americans don't worry to swim in our beaches. To eat our fish. Not too far from here, the fish are safe, is overblown. Reporter: The cleanup goes on. But what about the damage we can't see? Radiation on land and in the ocean that could be japan's invisible enemy for generations. Cecilia vega, abc news, fukushima, japan. We checked with some leading radiation experts here in the u.S. Who tell us so far no tests on the west coast have shown the levels of the kind of cesium radiation that would implicate radiation from fukushima. And you can see a lot more of cecilia vega's reporting tonight on "nightline."
This transcript has been automatically generated and may not be 100% accurate.