Oops. SpaceTiger, please excuse me, but when I wrote, "It that enough?", I was referring to the steps taken to ensure safety in commercial nuclear plants:
Current nuclear plants have safety systems, such as Emergency Core Cooling Systems (ECCS). Then there are the structure like the containment building, which is designed to withstand postulated accidents.
Then as part of the operation, there is training of personnel, and there are periodic inspections and testing of various systems, much more than was the case when TMI happened, and all as a result of TMI.
Otherwise, I would have addressed you directly with something like, "Have I answered your question to your satisfaction?"
The key question is - "Has the nuclear industry, specifically the operating utilities, suppliers of the technology and regulators done enough to ensure the safe operation of nuclear power plants?". Obviously, those opposed to nuclear will power will summarily argue, NO. Proponents will argue, YES.
If one argues, YES, then one can ask, "How do know that operating power plants are safe?" Simply saying the event at TMI-2 did not result in harm to the public (other than severe emotional distress for a lot of folks) is not enough to prove that nuclear power is inherently safe, or that other plants are not at risk for a catastrophic event that may compromise the safety of the plant personnel or public.
We demonstrate safety by a sustained program of inspection and training, and monitoring the performance of materials and systems during operation.
Take for example the steam generators (SGs) in many PWRs. The principal material for SG tubing was Inconel 600. The SGs and the tubes were designed with the intent of operating for the lifetime of the plant (40 yrs). However, in the mid 1980's, the rate of failure of SG tubing started to increase, particularly in high temperature PWRs (T
hot > ~ 320°C). The Inconel 600 tubing was failing after about 15-20 years, and many PWRs have had to replace the SGs, at costs on the order of $50-100 million/SG. The safety issue was related to the reactor coolant (with some level of radioactivity) escaping from the primary system and entering the secondary system.
On the BWR side, cracks were found in certain internal structures that were supposed to operate for the life of the plant. The cracks were caused by Intergranular Stress Corrosion Cracking (IGSCC), which was related to the electrochemical potential (ECP) and oxygen potential of the reactor coolant environment in which the stainless steel components were operating. Remedial steps have been taken to address this issue.
Many plants still have years, and in some cases decades of operation, even without the industry trend to 'extend' operation of many plants to 60 years. The major issue is "can we ensure 'safe' and reliable operation?"
I am hopeful, but cautious.
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Now, the question of this thread, is when is Global Warming Significant? Well, if Global Warming is now the cause of more floods and storms that cause an increase in destruction of property and loss of life, and drought, then it would seem that it is significant now.
There are two questions however:
1) What is the precise cause of global warming - a) is it a natural process? or b) is it due to man-made greenhouse gases?
2) If global warming is a 'significant' problem, what steps 'must' be taken to mitigate / remediate the problem.
