Posts Tagged ‘Containment building’


Salem Nuclear Reactor Unit 1 resumed operations Saturday after crews repaired a leak in the containment building that was discovered two days earlier.  The plant operator says about 4,800 gallons of radioactive water leaked out, and the water went through the plant’s drain system as designed. The entire system holds 90,000 gallons.

This was a quick fix compared to STP’s recent outages.  One from November 29, 2011 to April 24, 2012 and one from January 8, 2013 to April 22, 2013.  When outages last this long, it can have an affect on consumers pocketbooks.  These two outages cost just the City of Austin, TX, which owns a 16% portion of the nuclear plant, $27 million in replacement power costs, which the utility just passed along to consumers in the fuel charges.  That averaged out to $64 per customer since November 2011.

Could the cost to consumers of replacing old and deteriorating parts that have the plants down for long periods have been the deciding factor in retiring the San Onofre plant in California permanently.  What will be the fate of the aging nuclear plants across the country.

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Radiation hotspots of Cesium-137 from Chernobyl

Radiation hotspots of Cesium-137 in 1996 resulting from the Chernobyl nuclear power plant accident. -Wikipedia

Experts believe the radioactive core in reactor No. 2 at the crippled Fukushima nuclear power plant has melted through the bottom of its containment vessel and on to the concrete floor of the drywell below.  This new development has raised fears of a major release of radiation at the site, and some nuclear industry experts are saying that while they don’t believe there is a danger of a Chernobyl-style catastrophe, it’s not going to be good news for the environment.

The major concern when molten fuel breaches a containment vessel is that it will react with the concrete floor of the drywell, releasing radioactive gases into the surrounding area. At Fukushima, the drywell has been flooded with seawater, which was a last ditch effort to cool any molten fuel that escapes from the reactor and reduce the amount of radioactive gas released.

The drywell is surrounded by a secondary steel-and-concrete structure designed to keep radioactive material from escaping into the environment. But an earlier hydrogen explosion at the reactor may have damaged this, and the detection of water outside the containment area that is highly radioactive and can only have come from the reactor core, is a good indication that the containment area has been breached.

In the meantime, countries around the world are reassessing their nuclear power programs.  Britain has signaled that they could take a step back from nuclear power in the wake of the disaster.  Germany ordered a temporary halt to the country’s seven oldest reactors, and China is considering scaling back their program.

France, which gets about 80 percent of its energy from atomic power and has been the poster child for nuclear power during the recent nuclear renaissance, wants threats from airplane crashes and terrorists excluded from safety checks planned on European reactors following the Fukushima nuclear accident.  An interesting stance to take considering as recently as October of 2010, the French defense minister, Herve Morin told the French people that a terrorist threat exists, and could hit them at any moment.

At a minimum, governments should insist on two conditions for the future of the next generation of nuclear power plants: they have to be safe and they can not let the taxpayer be ripped off.  This is a opportunity for investment into renewable energy sources such as solar, wind and energy storage that don’t have the potential to be really, really bad news for the environment and the people who live in that environment.

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According to an update from the Nuclear Information and Resource Service (NIRS) an explosion has occurred at Fukushima Daiichi Unit 1.


Video of the aftermath of the explosion shows that the containment building
has been destroyed.


The NIRS update goes on to explain, in a General Electric Mark I reactor, the containment building is fairly weak and is considered the secondary containment. The primary containment is a steel liner that surrounds the reactor core. So far, video and photos have not been clear enough for us to determine whether this steel liner is intact.

Radiation levels at the site are reported to be 1,015 micro/Sieverts per hour. This is roughly equivalent to 100 millirems/hour. The allowable annual dose for members of the public from nuclear facilities in the U.S. is 100 millirems/year. The allowable annual dose for nuclear workers is 5,000 millirems/year. The average annual background dose from all radiation sources in the U.S. is about 360 millirems/year.

The explosion in Unit 1 was almost surely a hydrogen explosion. Pressure has been building up in the containment since offsite power was lost to the reactor because of the earthquake/tsunami. The GE Mark I reactor design is called a “pressure suppression” design. Rather than be built to withstand large pressure increases, General Electric sought with this design to attempt to reduce such increases in an accident scenario. The design has been criticized by independent nuclear experts and even Nuclear Regulatory Commission staff for many years (see: http://www.nirs.org/factsheets/bwrfact.htm).  In this case, the design clearly did not work. 24 U.S. reactors use the GE Mark I design.

The evacuation zone around the site has been expanded to 20 kilometers (about 12 miles). Another reactor at Fukushima Daiichi, Unit 2, is reported to be without cooling capability at this time. Three reactors at the nearby Fukushima Daini site are reported to be without cooling capability. These are GE Mark II designs, which are considered a mild improvement over the Mark I design. Both sites are on the Pacific Ocean, about six miles apart.

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