The use of nuclear energy for the generation of electricity has almost no direct impact on climate change, because it liberate almost no CO2 to the atmosphere as a result of the operation of the plant.

However, a severe nuclear accident in a nuclear power plant could has a direct impact on the environment but not necessary on climate change.

The management of nuclear waste, particularly spent nuclear fuel associated to the operation of a nuclear power reactor, could have also an impact on the environment if it is not properly managed but not necessary on climate change.

The enrichment of uranium has no direct impact on climate change but could has a negative impact on the environment in case of a severe accident in these facilities.

The sensitivite of uranium enrichment facilities is associated to the proliferation of nuclear weapons and not on the impact on the epclimate change.

See article: "Climate Change, Energy Security, and Nuclear Power"

http://www.sindark.com/NonBlog/Articles/CCNuclear.pdf

I agree with Jorge actually use of nuclear energy or uranium enrichment is not likely to have any climatic implications. I strongly believe if there is any it will reduce the carbon foot print.

Jorge and Saif seem to overlook the life-cycle emissions of nuclear energy. Several studies find that total CO2 emissions depend sensitively on the grade of uranium ore mined and milled. The lower the ore grade, the more fossil fuels are used for mining and milling it, and so the higher the CO2 emissions. The world is running low on high-grade uranium ore. Mining and milling low-grade ore with diesel will lift life-cycle emissions to 130-430 gm/kWh, much higher than life-cycle emissions from most renewable energy technologies and a large fraction of emission from gas-fired power stations.

Interesting how you referenced your own, non-peer reviewed article to support your claim that nuclear is not "low-emission" Prof. Diesendorf.

A systematic review of life cycle GHG emissions by scientists at the US National Renewable Energy Laboratory (NREL) found that median and mean nuclear fuel cycle GHG emissions were 12 to 18 g CO2e/kWhe.

http://onlinelibrary.wiley.com/doi/10.1111/j.1530-9290.2012.00472.x/abstract

Compare those statistics to the NREL's LCA studies conducted in parallel for other generating sources:

Coal = 980 g CO2e/kWhe

Coal with Boundary Dam 3 type CCS = 114 g CO2e/kWhe (my calculations not NREL)

Solar PV = 45 - 52 g CO2e/kWhe

Concentrating Solar = 21 - 23 g CO2e/kWhe

Nuclear = 12 - 18 g CO2e/kWhe

Utility Scale Wind = 12 - 16 g CO2e/kWhe.

Using LCA, how is nuclear not a "low emitter"?

Abolfazl, to answer your question: uranium mining, milling and enrichment are the largest contributors to total life-cycle emissions from nuclear power. And, as Prof. Diesendorf points out, this depends a great deal on ore grade. Ore grades in other parts of the world are considered "high" at 0.15%. Here in Saskatchewan the mines are producing ore grades as high as 10 - 20% and there's lots of land that still has not been explored.

Specifically with respect to enrichment, GHG emissions depend on three major factors.

1) How enriched does your fuel have to be? Canadian CANDU reactors, in contrast to US light-water reactors, require very little enrichment.

2) How are you enriching? Gas diffusion is slow, expensive and a high emitter compared to using centrifuges for enrichment (like ~10X less GHG's for centrifuges).

3) What is your electricity source while mining/milling and enriching? Ontario enriches and fabricates Canadian fuel and that province is powered ~60% by nuclear power and renewable energy. If it were enriched/fabricated in Saskatchewan (where Uranium is mined) the grid is 60% coal-powered. Thus although Ontario produces 7.4X as much electricity as Saskatchewan, it's total GHG's are only 1.7X higher.

Nuclear is the lowest GHG emitting non-renewable power source. That's the facts.

-Cam