Go to CNF homepage
The Canadian Nuclear FAQ  

by Dr. Jeremy Whitlock


To the Globe and Mail, regarding an article on CANDU safety and the positive void coefficient:

(Published in the 2009 July 1st edition - only the last two sentences.)


Nuclear's place

2009 July 1

To The Editor,
The Globe and Mail:

Martin Mittelstaedt's discussion of "positive void reactivity" in CANDU reactors ("Reactor design puts safety of nuclear plants into question", June 29) is a classic case of a little knowledge being a dangerous thing. In fact, the news that the regulator and utilities are engaged in an ongoing assessment of safety throughout the life of a reactor, is a very positive statement.

"Reactivity" is a form of feedback, and feedback is not necessarily bad; what matters is that it is characterized, understood, and accounted for. Contrary to the armchair opining of Mr. Stensil of Greenpeace, all reactors have sources of positive reactivity which must be accommodated within their respective safety systems. As with CANDU, this capability is revisited as all reactors age.

In fact, CANDU reactors are among the safest reactors operating today, and in some respects this is directly due to their positive void reactivity. Imagine a car that can sense the slightest hint of danger and begin responding long before the driver's reaction time kicks in. Imagine a reactor with two independent, fast-acting shutdown mechanisms that don't require human intervention.

In digging for dirt on CANDU, Greenpeace has missed the bigger picture and done a disservice to world-leading Canadian technology.


Dr. Jeremy Whitlock
reactor physicist, Chalk River Laboratories

[Back to The Canadian Nuclear FAQ]