When climate change hits hard and our infrastructure starts to decay, these will begin to fail. Decommissioning a nuclear reactor takes years. There are many that like Fukishima that are positioned by the ocean, unless completely decommissioned safely they will eventually flood. That will release radioactive material into the ocean. Given the other issues, there can be no long term survival of the ocean, as we know it. However, what will be terminal for mankind is if they go into meltdown. That will pollute the atmosphere.
The are sheep in Wales, 26 years after Chenobyl that are still being affected by the fallout. (thanks for the heads up ulvfugl)
The only way for these reactors to avoid meltdown is to make sure that civilization's infrastructure survives. The reactors have a backup generator, but that is not enough for what we are facing. Sustaining the infrastructure requires energy, and lots of it, always on demand.
The changes that will have to be made to survive heat events will require the ability to build new types of housing, and logistics. The logistics chain needs to be electrified, as fossil fuels are unsustainable. That requires a significant power source, much greater than is currently available.
Renewables are a great option, but the generation variability makes providing a constant load difficult. The ability to generate nationwide logistics chains using renewable electricity is unlikely in the near future. We haven't even achieved that using coal. Hydrogen would require a complete overall of our infrastructure. Electrifying the train network nationally could be done with minimal changes to the existing system.
In addition, we do not have a long time-frame in which to implement this.
The only source that is capable of doing a high constant load is Thorium. Thorium requires constant bombardment in order for it to react, so it cannot create its own chain reaction. Should the power station fail, it cannot go into meltdown. In the event of a terrorist attack or missile strike on the reactor, spilled fuel would only create a contamination zone in the immediate surroundings of the reactor.
When thorium is irradiated, or exposed to radiation to prepare it for use as a fuel in nuclear reactions, the process forms small amounts of uranium-232. That highly radioactive isotope makes any handling of the fuel outside of a large reactor or reprocessing facility incredibly dangerous. The lethal gamma rays uranium-232 emits make any would-be bomb-maker think twice before trying to steal thorium. (link)
There is the issue that with a small tweak in the processing chain you can make atomic grade material. If an element known as protactinium-233 is extracted from thorium early in the irradiation process, no uranium-232 will form. Instead, the separated protactinium-233 will decay into high purity uranium-233, which can be used in nuclear weapons. (link) This maybe a situation we just have to accept. We are already in a mutually assured destruction scenario.
As climate change will continue unabated, we must ensure that the energy infrastructure remains functional. We cannot rely on fossil fuels for the reasons mentioned elsewhere. Where possible we should use renewables, with the excess stored as hydrogen. Where that is not possible due to fluctuations we need to build Liquid Flouride Thorium processing plants as close to the legacy reactors as possible. There is now a revitalization of older technology called Transatomic that can generate power from nuclear waste, though it faces hurdles coming online. That way the infrastructure can be reused, and process of decommissioning can continue without interruption.
I am not confident that this will occur in the time-frame left to us.
So what is expected when there are failures that result in atmospheric pollution? It depends on the wind. The following is a general pattern.
Another variable in the process is that air circulation appears to be slowing down. (link) From the article "By the end of the century, more than half of the world’s population will be exposed to increasingly stagnant atmospheric conditions, with the tropics and subtropics bearing the brunt of the poor air quality." Stagnant air at the tropics would mean more opportunity for the nuclear pollutants to be cleared from the atmosphere by precipitation. So whatever the N. Hemisphere does to itself does not automatically translate into the same effect in the south.
It needs to be pointed out that a nuclear detonation is significantly different to a reactor meltdown. A meltdown can continue for days or weeks. High altitude points in Wales were contaminated from Chernobyl (1,697 miles). However, that does not indicate fatal contamination.
This is from the Worldwide Health Organization in regards to Chernobyl (link)
UNSCEAR reports that the average natural background radiation dose to human beings worldwide is about 2.4 mSv2 each year, but this varies typically over the range 1-10 mSv. However, for a limited number of people living in known high background radiation areas of the world, doses can exceed 20 mSv per year. There is no evidence to indicate this poses a health risk.So what was the result of Chernobyl?
| Population (years exposed) | Number | Average total in 20 years (mSv)1 |
| Liquidators (1986–1987) (high exposed) | 240 000 | >100 |
| Evacuees (1986) | 116 000 | >33 |
| Residents SCZs (>555 kBq/m2)(1986–2005) | 270 000 | >50 |
| Residents low contam. (37 kBq/m2) (1986–2005) | 5 000 000 | 10–20 |
| Natural background | 2.4 mSv/year (typical range 1–10, max >20) | 48 |
| Approximate typical doses from medical x-ray exposures per procedure: | ||
| Whole body CT scan | 12 mSv | |
| Mammogram | 0.13 mSv | |
| Chest x-ray | 0.08 mSv | |
| [1] These doses are additional to those from natural background radiation. | ||
While the effective doses of most of the residents of the contaminated areas are low, for many people, doses to the thyroid gland were large from ingestion of milk contaminated with radioactive iodine. Individual thyroid doses ranged from a few tens of mGy to several tens of Gy.
You can read the page for the resulting medical conditions from the link. None of which I would wish on my kids. It is expected that the increase in thyroid cancer incidence due to the Chernobyl accident will continue for many more years, although the long-term increase is difficult to quantify precisely.
So what conclusions can be made? It depends on the current weather patterns. A nuclear meltdown should force migration, however Chernobyl demonstrated that a lot of people will not move, simply because they have nowhere to go. The current Chernobyl exclusion zone covers an area of approximately 2,600 km2(1,000 sq mi). It doesn't stop there though, forest fires have been shown to release the radioactive elements back into the atmosphere.
Should simultaneous meltdowns occur due to climate change adversely affecting the local infrastructure, then the southern hemisphere will fare better. The Hadley cells would encourage high altitude contamination to go north. The equatorial patterns would delay the movement towards the south. Any delay is positive as it offers the potential for rain to flush it out of the atmosphere (and into the ocean). An estimate would be 1 to 6 months for contamination to reach the southern hemisphere, very dependent on where it started.
Again, if we take the scenario of a nuclear war. Depending on the ferocity, the result of which could actually be a nuclear winter. This is the subject of much debate, but the theory is massive city fire storms would result in smoke being lifted into the stratosphere, shielding the Earth from the sun's warmth. From a recent study;
The effect would be plummeting temperatures reminiscent of what happened after Krakatoa, and probably on a larger scale. It would theoretically wipe out the harvests. This is another strong point in favour of growing hydroponically, even if it is outside. The plants could be covered with tunnels. The radiation (from whatever source) must not get into the nutrients. In addition, it has been demonstrated that plants are more responsive to the temperature of the soil rather than the atmosphere. That does leave the door open to heating the nutrients.
Should the harvest be lost, the only option then is whatever has been dried or bottled from the previous harvest, or can be grown indoors under low light. It would seem then that a significant storage program is required.
The single lifetime human dose should be 500 mSv (0.71 uSv/hour) to the maximum of 4000 mSv (5.7 uSv/hour).
Again, if we take the scenario of a nuclear war. Depending on the ferocity, the result of which could actually be a nuclear winter. This is the subject of much debate, but the theory is massive city fire storms would result in smoke being lifted into the stratosphere, shielding the Earth from the sun's warmth. From a recent study;
After the Indian-Pakistani nuclear exchange…
- Five megatons of black carbon enter the atmosphere immediately. Black carbon comes from burned stuff and it absorbs heat from the sun before it can reach the Earth. Some black carbon does eventually falls back to Earth in rain.
- After one year, the average surface temperature of the Earth falls by 1.1 kelvin, or about two degrees Fahrenheit. After five years, the Earth is, on average, three degrees colder than it used to be. Twenty years on, our home planet warms again to about one degree cooler than the average before the nuclear war.
- Earth's falling temperatures reduces the amount of rain the planet receives. Year five after the war, Earth will have 9 percent less rain than usual. Year 26 after the war, Earth gets 4.5 percent less rain than before the war.
- In years 2-6 after the war, the frost-free growing season for crops is shortened by 10 to 40 days, depending on the region.
- Chemical reactions in the atmosphere eat away Earth's ozone layer, which protects Earth's inhabitants from ultraviolet radiation. In the five years after the war, the ozone is 20 to 25 percent thinner, on average. Ten years on, the ozone layer has recovered so that it's now 8 percent thinner.
- The decreased UV protection may lead to more sunburns and skin cancers in people, as well asreduced plant growth and destabilized DNA in crops such as corn.
- In a separate study, published in 2013, International Physicians for the Prevention of Nuclear War estimated 2 billion people would starve in the wake of a 100-A-bomb war.
The effect would be plummeting temperatures reminiscent of what happened after Krakatoa, and probably on a larger scale. It would theoretically wipe out the harvests. This is another strong point in favour of growing hydroponically, even if it is outside. The plants could be covered with tunnels. The radiation (from whatever source) must not get into the nutrients. In addition, it has been demonstrated that plants are more responsive to the temperature of the soil rather than the atmosphere. That does leave the door open to heating the nutrients.
Should the harvest be lost, the only option then is whatever has been dried or bottled from the previous harvest, or can be grown indoors under low light. It would seem then that a significant storage program is required.
The single lifetime human dose should be 500 mSv (0.71 uSv/hour) to the maximum of 4000 mSv (5.7 uSv/hour).
No comments:
Post a Comment