One thing that perhaps speaks the loudest in terms of the Sierra Club's impartiality is their paper "Tritium on Tap". As I mentioned a few days ago, its commonplace for scientists to demonstrate their biases in how they present data and the facts. This is a very good example of that.
I'm not going to address some of the papers they quote here, mostly because I've looked into some, and the issues seem too complex to summarize easily. Nevertheless, for the purposes of my argument I'll take it at face value that the papers are correct.
Their argument was that tritium poses a health hazard to the general public and that Canadian nuclear plants in particular are producing dangerous levels of tritium. To bolster their claim, they reference a German study that claimed to have identified a significant increase in the levels of childhood leukemia for people living within 5 km of nuclear reactors in that country. They also reference an American study which compiled a number of studies and identified a similar increase in the levels of childhood leukemia around nuclear reactors.
The problem with their argument, even if their facts are correct, is that none of that proves tritium emissions from nuclear reactors pose a health hazard.
Outside of primarily CANDU reactors, nuclear reactors do not produce tritium in any significant quantities. Any nuclear reactor using regular water as a moderator and coolant will be practically unable to produce tritium except by the most unlikely methods. Whereas in heavy water reactors (like the CANDU), tritium production is quite common. German and American nuclear reactors only produce negligible amounts of tritium, nothing anywhere near the level that would even cause observable increase over the background in local waterways.
The only study that would matter then would be if people living around Canadian CANDU reactors have an increased risk of childhood leukemia over and above the additional risk that these other papers identified as normal for German and American nuclear reactors.
While they may have set out to prove that tritium is dangerous, they have actually made it more difficult for themselves to make that claim.