Fort Calhoun: reactor on emergency generator on Sunday
The intrusion of water into certain buildings of the Fort Calhoun power plant forced the power plant to switch briefly to emergency power supply on Sunday, according to the Homaha World Herald.
http://www.omaha.com/article/20110627/N ... nuke-plantThe diesel generators have been successfully started to alleviate difficulties in supplying the power plant with electricity via the electricity network.
As in Fukushima, the cooling system of the power plant depends on the constant supply of electricity.
In addition, several explosions have created breaches on dikes upstream from the flooded nuclear power plant at Fort Calhoun in the USA.
The rupture of these dikes caused the previously protected cornfields to flood.
Government officials initially denied being behind the blasts, and suggest that angry farmers are suspected, but on Friday, emergency operations coordinator Jeff Theulen said the dikes may have be intentionally broken.
Indeed, a body of engineers from the US army had been working to level these dikes for a week. This work also resulted in the death of a driver whose truck fell from the dike.
Thus the private dyke of Vanmann n ° 30 located north of the Boyer Chute nature reserve was first excavated by the army before a breach was opened by explosives.
Two other breaches also caused the flooding of crop areas on this portion of the river.
The flooding of the plain by the rupture of agricultural dikes is obviously an attempt to create reservoirs upstream of the powerhouse in order to limit the flood in the main bed of the Missouri river.
In France we use to regulate floods what hydrometric engineers call passive flood clipping reservoirs which are flood zones whose definition is:
Passive flood capping works, to be placed in a small catchment area, with the objective of limiting the importance of floods downstream of this basin.
The principle is that of communicating vessels: above a certain level, the water overflows from the river bed to the reservoir, which moderates the flood in the river bed.
This is undoubtedly the reason why the army lowered the height of the dikes upstream of the river, the idea being that if the level still rises the fields receive the excess of water.
The decision to break the dikes shows that concern has escalated and that the authorities have switched to an emergency mode of action which was no longer intended to limit the peak of the flood but to lower the water level.
The situation seems more worrying than the nuclear authorities say, as implicitly confirmed by the evacuation of residents in an area of 15 km around the power plant (and the overflight ban) which represents more than 20.000 people.
Another indication is the decision taken by the nuclear authorities to lower the temperature of the water in the reactor considerably below the usual standards in order to have more time in the event of a breakdown of the cooling system.
The water is 308 m above sea level.
The alert level (307,85 m) requiring the plant to be shut down was exceeded on June 9.
We officially expect a rise of 60 cm which approaches the limit of 309 m above sea level.
At this level, the sandbag embankment surrounding the area of infrastructure connecting the power plant to the power grid could fail, which would likely result in the power plant being cut off from the power grid as happened in Fukushima.
The cooling system of the plant will then depend on the diesel generator sets that were started on Sunday.
However, these generators are only supposed to withstand a flood of 309m above sea level.
If the water rises even higher, secondary generators could take over up to a flood of 316.5 m.
These calculations do not take into account the damage that water can cause by erosion or pressure on the walls in the long run because the flood will not be expected before long months.
The crisis is therefore only just beginning.
No need to panic, in case of problem, it will suffice to apply the good old Duck & Cover method (dive & cover):