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(This blog should be read following the previous post ‘Could a Chernobyl happen in the UK?’).
Due to the events recently concerning the situation in Japan, I’ve decided to supplement my previous blog ‘Could a ‘Chernobyl’ happen in the UK?’ with some further information.
The first thing that I’d like to point out is that a 41 year old reactor has been hit by one of the worlds most intense earthquakes, coupled with a huge tsunami, and yet remains largely intact (the primary containment remains isolated) and significant melting of the fuel has been avoided. A dangerous amount of radiation has not been released, and there have been no fatalities amongst the public.
Rather than a boost to the ‘told you so’ attitude of the nuclear opponents, these latest events are surely a sign of the robust safety of nuclear power. In contrast, hundreds have been killed or injured in fossil fuel plants around the country.
It’s also worth noting that the UK is not near any major fault-lines, so our nuclear generating infrastructure is not subject to the same risks.
However, just to set worried minds at ease, I’ve decided to highlight some of the safety features of a modern nuclear power plant design (such as the AP1000 and the EPR, as was looked at in detail on the previous article). These features would prevent even the very minor consequences experienced at Fukushima.
The first is the advanced and substantial containment and shield buildings present in both designs. As we noted previously the EPR has a doubled layer containment dome, and the ap1000 has a separate shield building.
As you may have heard, the Fukushima back-up diesel pump systems failed, possibly due to sea-water contamination (or they may have just been old and unreliable). In the EPR design there are four separate diesel systems, each capable of providing cooling to the core. Two of these four systems are ‘bunkered’ and so are protected from external hazards. The safety back up systems of the AP1000 are based on a ‘passive’ arrangement, and are located within the primary containment (so would not be subject to external hazards). Passive systems are designed to operate in a ‘fail safe’ system, where simplicity is favoured over complexity (far less chance of age-related failure).
You’ve no doubt seen the explosions on TV. This was caused by hydrogen formation and venting to the atmosphere. In both the AP1000 and the EPR systems are present that safely recombine or ‘burn’ the hydrogen in an accident scenario and so avoid the possibility of an explosion of this type.
You’ve also no doubt have heard about the effort to cool the Fukushima cores with sea water. In an extreme accident scenario, the pumping of seawater would not be necessary in one of the two modern designs noted here. A large vat of water sits on top of the reactor core of the EPR and Ap1000, and could simply be drained in directly.
Finally the operators inside the plant are safe from any possible increase in radiation due to the a ‘control room habitability’ system, which vents the work space and provides safe levels of air. If this is not enough, both the AP1000 and EPR can be controlled remotely – i.e operators would not need to be on site to control the reactor.