They Continue To Be Safe...?

It has to qualify as a no-brainer that any government would avoid a colossal blunder by building a nuclear reactor close to a seismic fault line. 

Nor would any country logically choose to build nuclear reactors to provide most of that country's energy needs if that country is an island particularly and frequently exposed to earthquake activity, much less ensuing tsunamis.  Well, the brainy Japanese simply proceeded with building nuclear reactors for their domestic energy needs and they experienced the most disastrous earthquake never believed possible and a following tsunami, resulting in a world-scale nuclear melt-down.

And, you say, Quebec, which is hugely advantaged by sourcing its electrical energy through Hydro-Quebec's massive James Bay project built an atomic power station on a seismic fault line?  How utterly improvident.  And now there is a problem with Gentilly-2 - reaching the end of its service life, but on the verge of getting a refit (or closure) - having a problem with decaying concrete? 

This is important, since the containment enclosing the 675-megawatt CANDU 6 reactor's safety cannot be guaranteed.

Now that's a concern of monumental proportions.  As though there aren't enough concerns revolving around nuclear reactors as power sources with safety features impaired, with the stunning problem of how to resolve the issue of waste storage safely and permanently, and above all, the fallout, when it occurs, of accidents relating to human error. 

Trouble is, the metre-thick, steel-reinforced concrete structure surrounding the reactor represents the physical barrier against radioactive contamination - heaven forfend - escaping into the atmosphere through some unforeseen event, causing an emergency of wholesale proportions.  That final safety net, the thick wall of steel-reinforced concrete's reassurance is eroding even as the concrete itself succumbs to decay. 

"Special attention is needed for the containment structure in the longer term since it has been identified that containment concrete suffers from alkali-silica reaction (ASR)", according to a report by the Canadian Nuclear Safety Commission.  "There is no impact on the safety of any of Canada's nuclear facilities.  These facilities are licensed by the Commission because they continue to be safe."

Well, thank heavens for that.  Canadian nuclear facilities are dependable and safe and capable of producing the energy that we need when we need it.  We are told.

The common condition of concrete degradation has surfaced in three U.S. nuclear power stations as well.  The Nuclear Regulatory Commission has given warning to those operators that design strengths and assumptions "may no longer hold true" to original containment design plans.  That is, when ASR represented by cracks and fissures are seen to be present.  Who knew?  Didn't we think these structures were dependably failsafe?

Indestructible?  No.

And here's yet another blurb meant to instill confidence:  "The potential mechanical consequences of the chemical reaction, in terms of ultimate resistance of structural elements and overall structural behaviour, are unknown", according to the Canadian Nuclear Safety Commission.  Rest assured, however, the Canadian Standard Association sets standards for concrete containment buildings; in-service examination and testing requirements are in place.

As for ASR; when certain types of silica are used in bulk material in concrete, like crushed rock and sand, it reacts in the presence of water with chemicals such as sodium or potassium, commonly found in cement paste.  Aren't we all too familiar with the syndrome that manifests itself with salt interacting with water degrading concrete on the home front?

And how about freeze-and-thaw winter cycles pot-holing our roads?  Doesn't this sound familiar in the explanation of how ASR eventuates; the reaction between water, sodium or potassium found in cement paste produces a gel forming in the pores of concrete that expands causing stress and cracking, that becomes enlarged and exacerbated over time to present as large fissures, compromising structural integrity in the concrete.

Right, got it now.  Inexpensive, safe, efficient nuclear energy.