updated 1/7/2012 3:53:43 AM ET 2012-01-07T08:53:43

Japan says it will soon require atomic reactors to be shut down after 40 years of use to improve safety following the nuclear crisis set off by last year's tsunami.

Concern about aging reactors has been growing because the three units at the Fukushima Daiichi plant in northeastern Japan that went into meltdown following the tsunami in March were built starting in 1967. Among other reactors at least 40 years old are those at the Tsuruga and Mihama plants in central Japan, which were built starting in 1970.

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Many more of the 54 reactors in Japan will reach the 40-year mark in the near future, though some were built only a few years ago.

The government said Friday that it plans to introduce legislation in the coming months to require reactors to stop running after 40 years. Japanese media reported that the law may include loopholes to allow some old nuclear reactors to keep running if their safety is confirmed with tests.

The proposal could be similar to the law in the U.S., which grants 40-year licenses and allows for 20-year extensions. Such renewals have been granted to 66 of 104 U.S. nuclear reactors. That process has been so routine that many in the industry are already planning for additional license extensions that could push the plants to operate for 80 years or even 100.

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Japan does not currently have a limit on years of operation. It had planned to expand nuclear power before the meltdown, but has since ordered reactors undergoing routine inspections to undergo new tests and get community approval before they can be restarted. The new restrictions mean that only six Japanese reactors are currently running.

Power shortage to come?
The Asahi newspaper reported Saturday Japan is likely to face a power shortage if it carries out the 40-year rule, which barring loopholes would force 18 more reactors to shut down by 2020, and another 18 by 2030.

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The government has already decided to scrap six reactors at Fukushima Daiichi, where backup generators, some of them in basements, were destroyed by the March 11 tsunami — setting off the world's worst nuclear crisis since Chernobyl. The government has said it will take 40 years to fully decommission the plant.

It is unclear whether the age of the reactors was related to the nuclear crisis. The location of the generators, absence of alternative backup power and inadequate venting are believed to be more direct causes, but some critics have said the Fukushima plant showed signs of age, such as cracks in piping and walls.

Promising that nuclear plants may be gone in about four decades may help the government gain public support for getting more reactors running again.

The future of Japan's nuclear policy remains under review. Some people are worried about radiation in the food and water, as well as the health of children, who are more at risk than are adults to sicknesses from radiation exposure.

Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Photos: Japan: Tsunami clean-up

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  1. In a series of photos, parts of Japan hit by the earthquake and tsunami are shown shortly after the disaster, then after nearly three months of cleanup efforts. In this combo, in the first picture, taken March 11, 2011, tsunami waves surge over a residential area in Natori, Miyagi Prefecture, northeastern Japan. Then on June 3, 2011, power shovels are at work on reconstruction in the same area. On Saturday, June 11, 2011, Japan marks three months since the earthquake and tsunami. (AP) Back to slideshow navigation
  2. March 13, 2011: Destroyed houses and debris fill a parking lot of a shopping center in Otsuchi, Iwate prefecture, northeastern Japan, two days after the disaster.
    June 3, 2011: Houses and debris are cleared. (AP) Back to slideshow navigation
  3. March 14, 2011: Tsunami survivors walk with plastic containers and kettles to carry drinking water through a street blocked by a fallen tank and other debris in Kesennuma, Miyagi Prefecture, northeastern Japan
    June 3, 2011: Only one damaged house, center, stands along the same street. (AP) Back to slideshow navigation
  4. April 6, 2011: A sightseeing boat sits on a building in Otsuchi, Iwate prefecture, northeastern Japan.
    June 3, 2011: The same area with the boat gone. (AP) Back to slideshow navigation
  5. March 19, 2011: Vehicles park on the ground of a junior high school serving a refugee center in Rikuzentakata, Iwata prefecture, northeastern Japan.
    June 3, 2011: The same area with temporary houses set up for survivors. (AP) Back to slideshow navigation
  6. March 13, 2011: A group of firefighters head for a rescue operation in Minamisanriku, Miyagi Prefecture, northeastern Japan.
    June 6, 2011: A truck goes by the same road lined with electric poles. (AP) Back to slideshow navigation
  7. March 16, 2011: Buildings are surrounded by debris in Onagawa, Miyagi prefecture, northeastern Japan.
    June 3, 2011: The debris is almost cleared. (AP) Back to slideshow navigation
  8. March 12, 2011: A ship swept away by tsunami lies among other debris in Miyako, Iwate Prefecture, northeastern Japan.
    June 4, 2011: A man on a bicycle pedals past a pedestrian on the same road. (AP) Back to slideshow navigation
  9. March 18, 2011: Fire engines park among the debris as a search for missing people goes on in Rikuzentakata, Iwate prefecture, northeastern Japan.
    June 6, 2011: The debris is almost cleared. (AP) Back to slideshow navigation
  10. March 20, 2011: A damaged house stands in a flooded residential area in Kesennuma, Miyagi Prefecture.
    June 3, 2011: The sun shines over the same area. (AP) Back to slideshow navigation
  11. March 12, 2011: A sea coast is filled with destroyed houses and debris at Ishinomaki, Miyagi prefecture.
    June 3, 2011: The same area with the houses and debris cleared. (AP) Back to slideshow navigation
  12. March 13, 2011: A burned pickup truck lies among debris swept away by tsunami in Kesennuma, Miyagi Prefecture.
    June 3, 2011: Marguerites are in bloom along a cleared street corner in the same area. (AP) Back to slideshow navigation
  13. March 13, 2011: Debris is piled up by damaged buildings in Ofunato, Iwate prefecture.
    June 3, 2011: Several houses have been demolished. (AP) Back to slideshow navigation
  14. March 12, 2011: Two-car trains lie in ruin after being swept away by tsunami at Shinchi station, Fukushima Prefecture, with only its railway bridge section left standing.
    June 3, 2011: A truck is parked near the bridge. (AP) Back to slideshow navigation
  15. March 24, 2011: People walk along Prefectural Highway 30 sandwiched by floodwaters in Ishinomaki, Miyagi Prefecture.
    June 4, 2011: In the same area, an earth mover goes on with reconstruction work. (AP) Back to slideshow navigation
  16. March 23, 2011: Damaged houses stand amid debris swept away by tsunami in Miyako, Iwate Prefecture.
    June 3, 2011: Debris is almost cleared. (AP) Back to slideshow navigation
  17. March 13, 2011: A tsunami-beached ship lies among debris in Kesennuma, Miyagi prefecture.
    June 3, 2011: The ship remained there with little cleaned around it. (AP) Back to slideshow navigation
  18. March 12, 2011: Damaged cars are submerged in flooded residential area with other debris swept away by tsunami in Kesennuma, Miyagi Prefecture.
    June 3, 2011: A car goes by debris in the cleared street. (AP) Back to slideshow navigation
  19. March 18, 2011: An overturned car sits on the rooftop of a damaged building in Onagawa, Miyagi Prefecture.
    June 3, 2011:The car still stays in the same position on the building while its surrounding area is almost cleaned up. (AP) Back to slideshow navigation
  20. March 14, 2011: A shinto torii, or gateway, leading to Kozuchi shrine stands among the debris in Otsuchi, Iwate prefecture.
    June 3, 2011: The debris nearly all cleared. (AP) Back to slideshow navigation
  21. March 24, 2011: Ships swept away by tsunami are piled up each other on the ground in Kesennuma, Miyagi Prefecture.
    June 3, 2011: The ships stay in the same position in the area almost unchanged. (AP) Back to slideshow navigation
  22. March 14, 2011: Rescue workers search for tsunami survivors amid debris in a residential area in Higashimatsushima, Miyagi Prefecture.
    June 3, 2011: The ships stay in the same position in the area almost unchanged. (AP) Back to slideshow navigation
  23. March 12, 2011: A ship swept away by tsunami sits amid debris-covered residential area in Kesennuma, Miyagi Prefecture.
    June 3, 2011: The ships stay in the same position in the area getting cleaned up. (AP) Back to slideshow navigation
  24. March 15, 2011:A a ship swept away by tsunami sits amid debris-covered residential area in Kesennuma, Miyagi Prefecture.
    June 3, 2011: The ship stays in the same position in the area almost cleaned up. (AP) Back to slideshow navigation
  25. March 12, 2011: Residents wait for rescuers on the balcony of the debris-dangling house in Rikuzentakata, Iwate prefecture.
    June 3, 2011: The debris almost cleared. (AP) Back to slideshow navigation
  26. March 15, 2011: Ddebris from houses swept away by tsunami are left untouched in Ishinomaki, Miyagi Prefecture.
    June 3, 2011: Some buildings stand in the same area almost cleaned up. (AP) Back to slideshow navigation
  27. March 24, 2011: A TV antenna leans near a stone statue of the guardian deity of children sitting among the debris in Ishinomaki, Miyagi prefecture.
    June 4, 2011: The debris cleared and the statue wearing a new red cap. (AP) Back to slideshow navigation
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Interactive: Aging nuclear plants

  1. Above: Interactive Aging nuclear plants
  2. Interactive How nuclear plants work

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