Here's a graphic from the Paul Scherrer Institut (bigger means safer):
|Contributions of Fission Products to Radiotoxicity after ten years|
|55.95%||strontium||21.75||90Sr||28.79 y||11.79||300 y|
|43.44%||caesium||70.52||137Cs||30.04 y||27.52||300 y|
|0.401%||europium||4.473||154Eu||8.593 y||0.56||100 y|
|0.033%||cadmium||3.795||115mCd||44.6 d||0.00529||30 y|
|0.076%||other radioactive||428.2||10 y|
See the links to detailed reports of used LWR fuel contents below.
Detailed radiotoxicity curves were computed from radioactivity of fission products having half lives longer than five years.
For a completely closed system that produces no long-lived transuranics, a fast-neutron reactor with fuel reprocessing, such as described by Till and Chang, is necessary.
Spent fuel has a value of $71,668,246.68 per tonne (52.185 MWe-yr). Fuel processing ought to be a profit center, not a cost center.
We will need liquid hydrocarbon fuels indefinitely for airplanes, probably for ships, heavy construction equipment, farm equipment, and heavy freight too large for trains, and maybe for long-distance auto travel.
Fortunately, liquid hydrocarbon fuels can be made from CO2 plus hydrogen using the Fischer-Tropsch process.
Hydrogen can be extracted from seawater using the copper-chlorine thermochemical process at an energy cost of 532 kJ/mol (about 0.079 MWh/T). One step of the process needs heat at about 1000o Fahrenheit (530o Celsius), almost exactly the core temperature of a nuclear power reactor.
The concentration of CO2 in seawater is 140 times greater than in the atmosphere. Removing CO2 from seawater exploits the oceans' enormous surface area to remove it indirectly from the atmosphere.
In CO2 extraction from seawater using bipolar membrane electrodialysis (Energy & Environmental Science 2012, 5 7346 DOI:10.1039/c2ee03393c), Eisamen et al described the PARC BPMED process to extract 52% of dissolved CO2 from seawater at an energy cost of 242 kJ/mol (about 1.5 MWh/T). There's an abstract here and my copy here.
PARC estimates that liquid hydrocarbon fuels can be made from seawater plus energy using the BPMED, copper-chlorine, and Fischer-Tropsch processes, for $3.00/gallon. The energy density of automotive gasoline is about 12.5 MWh/T.
The US Navy is developing a method using these processes to make jet fuel aboard nuclear aircraft carriers.
Burning hydrocarbon fuels made from seawater would be a net negative CO2 transfer to the atmosphere and oceans. CO2 that results from burning the fuels would go into the atmosphere, and eventually back into the oceans, but surely some would be trapped in plants and soils. CO2 extracted from seawater could also be sequestered in geologic storage.
The United States has 90,000 tonnes of spent fuel and 900,000 tonnes of depleted uranium. This is enough to fuel an all-nuclear all-electric 1,700 GWe American energy economy for 575 years -- longer than that to the extent solar and wind contribute. The long term attraction is that it is essentially limitless. Uranium salts are water soluble, and are continuously entering the oceans from the bottom and in rivers. The concentration of uranium in seawater and ocean-bottom rocks is in equilibrium. As uranium is taken from seawater, more enters from rocks. There is enough uranium already in the oceans to provide all the energy humanity currently uses for a million years. Uranium can be extracted from seawater, but this will not be necessary for a very long time.
Essential reading if you want a deeper understanding of the way a fast-neutron reactor creates more fuel than it consumes, why the Argonne design is inherently safe (and read David Baurac's article), how it works with pyroelectric refining to destroy nuclear waste, and why nuclear power, especially using this process, is irrelevant to weapons proliferation.
Nuclear power is "the energy source that can save our planet from another possible disaster: catastrophic climate change.... Nuclear energy is the only large-scale, cost-effective energy source that can reduce these emissions [of CO2] while continuing to satisfy a growing demand for power...."
"Imagine a nuclear power plant so safe that even the worst emergencies would not damage the core or release radioactivity. And imagine that this is achieved not with specially engineered emergency systems, but through the laws of nature and behavior inherent in the reactor's materials and design...."
The Soviet Union had no safety culture and no licensing criteria. The Chernobyl reactor should never have been built. It would not have been licensed in any other country. The fire is as relevant to other nuclear reactors as the crash of the Hindenburg is to a Boeing 777 or Airbus 380. But here's what the UNSCEAR report said about it:
134 plant operators and emergency responders at Chernobyl were exposed to sufficient radiation to develop acute radiation syndrome, which caused 28 deaths. Two others died from injuries not caused by radiation (falling debris), one from coronary thrombosis, and three in a helicopter crash. I don't count those six as "nuclear related." Notwithstanding that the report noted there is
"no scientific means to determine whether a particular cancer in a particular individual was or was not caused by radiation... [there is] no scientific evidence of increases in overall cancer incidence or mortality rates or in rates of non-malignant disorders that could be related to radiation exposure...,"the report attributed fifteen excess cases of fatal thyroid cancer, compared to earlier decades, out of 6,000 cases reported between 1991 and 2005, to the accident. These were inexcusable, as they could easily have been prevented by distributing potassium iodide, and quarantining locally-produced foods, especially milk. The Soviet government did neither.
In the most affected regions (northwestern Ukraine, Belarus, and southwestern Russia) the average additional radiation dose to the general public over the period 1986-2005 was about nine millisieverts (mSv), or 0.45 mSv/yr. The report notes that residents
"need not live in fear of serious health consequences."
"Japanese people receive an effective dose of radiation from normally occurring sources of, on average, about 2.1 mSv annually and a total of about 170 mSv over their lifetimes.... No radiation-related deaths or acute diseases have been observed among the workers or general public exposed to radiation from the accident.... For adults in Fukushima Prefecture, the Committee estimates [the increase in] average lifetime effective dose to be of the order of 10 mSv or less... discernible increase in cancer incidence in this population that could be attributed to radiation exposure from the accident is not expected."
To put this in context, the dose from one abdominal and pelvic CT scan with and without contrast is about 30 mSv. The annual dose on the Tibetan plateau is 13-20 mSv. Exposure on beaches in Guipari, Brazil varies from 175 to 1148 mSv/yr. The X-ray dose to treat prostate cancer is 72 Sieverts (not mSv) delivered over a period of 56 days.
Tokyo Electric Power Company (TEPCO) was ordered to shut down the aging Fukushima reactors eight years before the earthquake. They got permission to keep them open provided they sought advice from the US Nuclear Regulatory Commission (NRC). They sought advice but ignored it. NRC advised them to move the backup generators out of the basement to high ground, and to bury the fuel tanks on high ground rather than leaving them on stilts on the beach. The tsunami washed away the fuel tanks and filled the basement with mud.
The incompetent and mostly unnecessary evacuation of 150,000 residents of Fukushima resulted in 1,500 deaths. For most residents, the advice should have been shelter in place, drink bottled water, and do not eat locally grown food, until told otherwise. TEPCO employees were prosecuted for removing hospital patients from life support to prevent the one-in-a-billion chance of exposure to sufficient radiation to cause illness. The dirt in Fukushima is half as radioactive as the dirt in Denver. Residents could safely return to their homes. Instead, seven years later, thousands of Japanese are still living as refugees in their own country.
"As renewables can't save the planet, should we allow them to destroy the environment?"
"While many modelled scenarios have been published claiming to show that a 100% renewable electricity system [that excludes nuclear power] is achievable, there is no empirical or historical evidence that demonstrates that such systems are in fact feasible."Publisher's link: http://www.sciencedirect.com/science/article/pii/S1364032117304495 (requests a fee)
"This paper highlights the physics of energy to illustrate why there is no possibility that the world is undergoing -- or can undergo -- a near-term transition to a 'new energy economy'."
"Trying to combat climate change exclusively with today's renewable energy technologies simply won't work...."
"Renewables have captured the public's imagination, but can they actually be scaled up to power the entire nation?" The authors' conclusion was "no."Conley and Maloney published a summary in EnergyPost with the same title
"In this paper, we evaluate this study and find significant shortcomings in the analysis. In particular, we point out that this work used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions. Policy makers should treat with caution any visions of a rapid, reliable, and low-cost transition to entire energy systems that relies almost exclusively on wind, solar, and hydroelectric power."
"The utopian ambition for variable renewable energy is to convert it into uniform firm capacity using energy storage. Here we present an analysis of actual UK wind and solar generation for the whole of 2016 at 30 minute resolution and calculate the grid-scale storage requirement. In order to deliver 4.6 GW uniform and firm RE [renewable energy] supply throughout the year, from 26 GW of installed capacity, requires 1.8 TWh of storage. We show that this is both thermodynamically and economically implausible to implement with current technology."
"Can storage requirements be reduced to manageable levels by producing more renewable energy than is needed to fill demand and curtailing the surpluses? The answer is no. Curtailment does indeed reduce storage requirements, but not to manageable levels. This would appear to eliminate the possibility of developing a grid powered 100% by intermittent renewables. Backup generation will always be needed to fill demand when the sun doesn't shine and the wind doesn't blow."No matter how much excess solar capacity is built, the sun still doesn't shine at all at night, and not much in bad weather.
"Preventing nuclear plant retirements is a cost-effective carbon avoidance strategy. The premature retirement of U.S. nuclear power plants could eliminate some of the benefits of proposed carbon regulations."
"When an operating nuclear plant shuts down, a big chunk of carbon-free energy is lost. A big chunk. There's just no way to spin that as a good thing. The five nuclear plants shut down between 2013 and 2016 alone produced as much electricity as all US solar put together. Carbon-wise, that means the next doubling of US solar will mostly be spent trying to make up for nuclear losses."
I waited to comment on the SA blackout: reflections on preliminary
findings, Ben Heard explains that the entire grid in the State of South
Australia failed after a windstorm because of a lack of inertia (i.e., frequency
stability). There was insufficient frequency stability, so more and more
providers had to shed load to prevent damage to their systems. What provides
inertia on an electricity distribution grid? Heavy synchronous rotating
generators -- coal, gas, nuclear, hydro. The relatively clean, modern, 485 MWe
combined-cycle gas generator in Adelaide was offline because its economics had
been subsidized away to pay for wind from the public purse.
The United States cannot produce enough steel to produce an all wind-and-solar energy system in anything approaching a reasonable time frame. We would be dependent upon China, India, Japan, and Korea, where other customers would be competing. In contrast, a nuclear power plant needs about 50 tonnes of steel and 100 cubic meters of concrete per megawatt of capacity.
There was a much more severe event, called the Carrington Event, in 1859.
The Sun does this every eleven years or so, and it hits the Earth every sixty years or so.
Solar panels are inherently vulnerable to EMP, either caused by a solar eruption or nefarious actors. Windmills are too, but would not be nearly as devastated. The millions of miles of additional wiring necessary to a nationwide "all renewable" distribution system would be a giant EMP antenna. It would be severely damaged, and would transmit the damage into every level of the system. It would take decades to rebuild and recover, at enormous expense.
Nuclear power plants, inside four-foot-thick concrete domes, laced with steel, or in underground "silos" as NuScale envisions, are inherently invulnerable to EMP. Small (50-350 MWe) modular nuclear power plants would each have enough capacity and reliability to power their communities independently from myriads of other small sources. They would be distributed throughout the country, and would require a very much smaller interconnect, which would be a very much smaller EMP antenna.