A containment building, in its most common usage, is a steel or reinforced concrete structure enclosing a nuclear reactor. It is designed, in any emergency, to contain the escape of radiation to a maximum pressure in the range of 60 to 200 psi ( 410 to 1400 kPa). The containment is the fourth and final barrier to radioactive release (part of a nuclear reactor's defence in depth strategy), the first being the fuel ceramic itself, the second being the metal fuel cladding tubes, the third being the reactor vessel and coolant system.
Each nuclear plant in the US is designed to withstand certain conditions which are spelled out as "Design Basis Accidents" in the Final Safety Analysis Report (FSAR). The FSAR is available for public viewing, usually at a public library near the nuclear plant.
The containment building itself is typically an airtight steel structure enclosing the reactor normally sealed off from the outside atmosphere. The steel is either free-standing or attached to the concrete missile shield. In the United States, the design and thickness of the containment and the missile shield are governed by federal regulations (10 CFR 50.55a), and must be strong enough to withstand the impact of a fully loaded passenger airliner without rupture.
While the containment plays a critical role in the most severe nuclear reactor accidents, it is only designed to contain or condense steam in the short term (for large break accidents) and long term heat removal still must be provided by other systems. In the Three Mile Island accident the containment pressure boundary was maintained, but due to insufficient cooling, some time after the accident, radioactive gas was intentionally let from containment by operators to prevent over pressurization. This, combined with further failures caused the release of minimal amounts of radioactive gas to atmosphere during the accident.
Information is still being studied of the failures at Fukushima. While the plant had operated safely since 1971, an earthquake and tsunami well beyond the design basis resulted in failure of AC power, backup generators and batteries which defeated all safety systems. This resulted in partial or complete meltdown of fuel rods, damage to fuel storage pools and buildings, significant release of radioactive debris to surrounding area, air and sea, and resorting to the use of fire engines and concrete pumps to deliver cooling water to spent fuel pools and containments.
Other articles related to "containment building, containment":
... On November 21, 2009, a radiation leak occurred inside the containment building of TMI-1 while workers were cutting pipes ... monitor at the temporary opening cut into the containment building wall to allow the new steam generators to be moved inside showed a slight increase in a reading and then returned. 2009 (2009 -11-22), it is believed that no radiation escaped the containment building and the public is not in any danger ...
... the basic design criteria for isolation of lines penetrating the containment wall ... Each large pipe penetrating the containment, such as the steam lines, has isolation valves on it, configured as allowed by Appendix A generally two valves ... to install the isolation valves near to where the lines exit containment ...
... most likely end up on the concrete floor of the primary containment building ... thick flat concrete floor in the primary containment will often be sufficient protection against the so-called China Syndrome ... The Chernobyl plant didn't have a containment building, but the core was eventually stopped by the concrete foundation ...
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