Wednesday, 3 October 2018

No mostly. Sometimes maybe but not really.


We visited the forest occupiers. Interviewed. Explained the lignite is 10 GW, and 10 GW of nuclear has been forced closed in Germany.

Would they support #nuclear to preserve the forest?


Sunday, 15 July 2018

Simple Molten Salt Reactor, by Moltex LLP

Reblog. Copied from Energy Knot blog. Moltex SSR

Moltex LLP is a small UK engineering design company based in London. On 20 Oct Ian Scott of Moltex presented his SMSR, lasting 15 minutes, at a House of Lords meeting.

Ian was influenced by the very first Molten salt design from 1950, which placed molten fuel inside narrow cylinders. Ian's design has several such cylinders full of fuel inside a tank of coolant. Both coolant and fuel are molten salts. The fuel circulates in these cylinders by convection, as does the coolant in the tank. A 1 GWe reactor will have a tank about 8 metres in diameter. There are no pumps moving molten salts - circulation is all done by convection. The tank will be a nickel alloy, probably Hastelloy. No moderator either, so it's a fast reactor. Ian reckons the reactor will last many decades.

Stated advantages of the SMSR

  • unpressurized
  • the reaction is barely critical
  • no volatile fissile materials will be left in the reactor (gases will bubble out)
  • safe coolant
  • no pumps
  • materials are all standard industrial parts
  • cheap
  • fuel will be made from spent nuclear fuel, SNF, extracted by a "simple single-stage process".

Potential Issues:

  • The primary coolant is sodium chloride. Natural chlorine is a mixture of isotopes: mainly Cl-35, Cl-37. Cl-36 is present as a trace, and is radioactive, half-life = 300k years, undergoing mainly beta decay to Ar-36, S-36. The thermal neutron cross-section of chlorine-35 = 35.5 σa/barns [can't find the fast version, but the thermal spectrum is worryingly high]. It looks like quite a lot of neutrons may be lost to chlorine-35 absorption, producing chlorine-36 which is radioactive. Ian does not believe enough neutrons will be lost to make the reactor too inefficient, but the coolant will become radioactive. A way around this is to use isotopically separated chlorine-37 in the coolant salt. Using chlorine-37 alone, will prevent chlorine-36 forming and Cl-37 is stable against neutron bombardment. Several quite inexpensive routes are available for the separation of Cl-35 / Cl-37. The cost estimate has been done, still giving a very viable project.
  • The fuel tubes are a consumable item with an anticipated 5 year life, functioning in a similar manner to fuel rods and needing periodic replacement.

A thorium breeder?

Ian believes that a converter makes economic sense now. A breeder will have to wait till the future:

There would then be an economic case for developing a nuclear breeder version of the reactor (this exists now in outline), which would operate on the thorium fuel cycle. That outline design is far simpler, safer and cheaper than current designs for sodium cooled fast breeder reactors.
- [Moltex Energy LLP – Written evidence, section 29]

The best introduction to the SMSR may be references: 6, 4 [translated via Google], 2, 1, in that order. Refs. 2, 1, 3 contain all the detail.

  1. Slides
  2. Evidence to House of Lords, pages: "Moltex Energy LLP – Written evidence"
  3. Patent Application WO-2014128457-A1
  4. Blog on Moltex (in French)
  5. Moltex LLP
  6. Next Big Future - UK MSRs

Saturday, 8 July 2017

Pumped Hydro.

Consider the new Swiss Lake Mutt pumped hydro plant. Should we be building more of them? Can we?

In UK, pumped hydro has never been used as an energy storage feature. I mean it's purpose is not to store energy. Energy storage is just something it does in order to work. UK pumped hydro is used to meet peak demand. Because hydro "switches" electricity onto the grid faster than anything else can. We face peak demand every day so the capital is always in use and the plant provides the grid with electricity every day (so gets revenue daily).

RE advocates don't seem to get this. UK pumped hydro was very expensive to build but eventually pays for itself because it's constantly used. RE advocates talk of pumped hydro as an energy store mechanism to alleviate unreliables. If so, capital plant will not be constantly in use. Unless pumped hydro is regularly making money by selling electricity to the grid, it won't make economic sense.

That's probably the reason RE advocates want the grid itself to pay for storage. If the grid has to pay, existing fossil plant like gas will be paying to put its competitor (peaking provider) in place!

Technically speaking - I'm not sure that UK pumped hydro ever did pay for itself. It was built when the UK grid was one nationalized company. Their accounting systems were bizarre to most outsiders. Indeed - bad accounts - is the reason nuclear became unpopular with UK politicians in the 1990s as the grid was privatised and many of the nuclear plants (Magnox reactors) were impossible to privatise. The effect of impossible accounting on politicians is revealed in Simon Taylor's "Fall and Rise of Nuclear Power in Britain".

Sunday, 23 April 2017

Decommissioning - facts and fallacies.

I wrote this after listening to The Nuclear Humanist (Thies Beckers') response to Robert Llewellyn's (Fully Charged) snipes against nuclear power. Thies is right but there's an outstanding question he should address to Robert Llewellyn, Mark Z. Jacobson and their ilk. Do you support early decommissioning of German nuclear power reactors?

UK situation.

In UK, all the DECC decommissioning costs (to UK government) are for weapons sites (including submarines) and shut Magnox reactors (which are now all shut). Costs of decommissioning other power reactors: PWR and AGR, is solely the responsibility of the owners. EDF own all remaining power reactors. EDF have a fund growing annually for this mandated by UK government. It's a kind of tax. ~ 5% of their revenue. This is how decommissioning is handled in all Western democracies I know of.

Magnox spent fuel is all being reprocessed to remove plutonium. UK has a PUREX plant called THORP to do this. This extracts plutonium from spent fuel. That plutonium is not quite weapons grade but could provide very useful fuel for fast reactors. Alternatively - if anti-nukes have their way this plutonium will have to be disposed of too so that is cannot be used to make even substandard nuclear weapons. Only Magnox reactors will bear this extra reprocessing cost because Magnox reactors were special. The design was dual purpose. The spent fuel can be used to make nuclear weapons. Magnox are also far more expensive to decommission than PWRs because decommissioning was not considered in advance of their design. A flaw never to be repeated by other power reactor designs.

Europe and Sweden

Sweden has no Magnox reactors. Their PWR reactor decommissioning will be entirely the responsibility of the owners (via the decommissioning fund). Provided they are not shut prematurely, their decommissioning fund will bear the cost. The same kind of fund as per UK EDF reactors.

In Germany, plants are being shut too soon. So German decommissioning funds are not yet big enough to bear the cost. I wonder what Llewellyn and Jacobson think of that? Was early German shutdown a good idea?

Tuesday, 20 December 2016

Report by Congress says: Obama Admin Fired Top Scientist to Advance Climate Change Plans

I doubt Obama's media darlings will be reporting this

Dec 20, 2016: news report: Congress: Obama Admin Fired Top Scientist to Advance Climate Change Plans, Investigation claims Obama admin retaliated against scientists, politicized DoE

Full report: U.S. Department of Energy Misconduct Related to the Low Dose Radiation Research Program (pdf)

Obama administration fired a top scientist who got out of line and wanted scientific research done into actual harms of banned substances.

Background: For decades now, the old ruling against carcinogenic substances: No safe dose, based on a linear, no-threshold, LNT, dose-response model has been disputed. No-safe dose is widely used by regulatory agencies, especially for carcinogenic substances. Some of the problems with no-safe dose are: at least one agency thinks everything is a carcinogen (such as the UN IARC who literally say 99.9% of everything (substance and activity) they investigated was carcinogenic. They sub-contracted NRDC researchers to find that. The no-safe dose model assumes there is no real protection against carcinogens, in that it considers every animal to be, more or less, equally susceptible. It believed genetic damage is carried down the lineage. That is absolutely not the case. In recent decades, modern biology found several mechanisms, which work at the cellular level, by which animals protect themselves from cancer. Some animals have high protection against cancer, such as: Elephants, blind mole rat, naked mole rat, water bears (tardigrades) to name but 4. These protective measures use a variety of mechanisms (proteins to protect DNA, widely different levels of cell lysis, mechanisms to prevent DNA insertion by alien creatures such as viruses, etc.). Different DNA repair mechanisms are present at a cellular level to repair damaged or broken DNA. Humans are about mid-way. Not the most susceptible animal but certainly not the least.

The cost of no-safe dose to industry may be in the trillions. It is certainly at least tens of billions each year. I guess no one knows because we don't really study it. Regulatory agencies never bothered with cost-benefit before they enacted no-safe dose. They do not review cost-benefits. E.g. Notice how Wikipedia don't even discuss cost-benefit. Presumably because there are not enough comprehensive studies; as academics and regulators are too cowed to write them. One might get sacked.

Scientists in the nuclear power, and radiation medicine (anti-cancer) industries have tried for years to establish a threshold dose instead. It looks like the Obama administration fired at least one scientist to make an example and establish who's in charge. To establish who has the right to decide what science says.

Thursday, 8 December 2016

Sarcy sarcophagus

Big song and dance over €1.5bn spent on a sarcophagus, or shield, above the exploded Chernobyl reactor. But what was the point of it? It protects no one from radiation. Radiation travels in straight lines. No one flies in the airspace above the reactor. A shield around the reactor could've been something as simple are a 4 metre wide earthwork about 5 metres high. The 3 neighboring reactors at Chernobyl continued operation for years after. They were shut in 1991, 1996, and 2000. For 14 years, when the radiation levels are much higher than now, workers continued to operate those reactors. The sarcophagus is a 1.5 billion Euro moral statement financed by Chernobyl Shelter Fund saying : nuclear power is forever dangerous - be very afraid.
This sarcophagus is certainly an admirable engineering accomplishment : it is the largest movable object ever built by humanity, but it is useless health wise.

The world is spending €1.5bn (one and a half billion euros) to protect itself from harmless levels of radiation.
For the same €1.5bn Ukraine could've built an advanced molten salt test reactor and prototype. They could've had cheaper, safer nuclear power instead of relying on Russian gas so much. €500 million of that money came from the European Bank for Reconstruction and Development (EBRD). Rather construct and develop something useful to increase wealth. They chose to throw the money away.

Monday, 5 December 2016

Brief history of radiation protection. What does it mean?

People are prone to jump on moral crusades. We see it today with global warming. Back in the day, radiation and cancer were a moral crusade.

In the early days of radiation it was the Wild West. No radiation limits. Marie Curie died of radiation induced cancer. Radium girls often caught mouth cancer. By the 1920s it was clear that high radiation doses presented a serious health risk. Dose limits were imposed in the early 1930s. OMG! - how did humanity survive before we had environmentalists to protect us? Easy. Sensible folks noticed something was wrong and proposed regulation to stop bad things. Yet even back then I bet we had the equivalent of SJWs; crusaders who pushed regulation too far.

No widespread major illnesses developed among radiation workers after maximum dose limits were imposed in the early 1930s. Consider the following timeline. In response the development of the atomic bomb radiation protection standards were increased. Later in response to the threat of nuclear power, radiation protection standards were ratcheted tight.

  • 1931: National Council on Radiation Protection establish first formal dose limit = 1 mGy/day
  • 1934: International X-ray and Radium Protection Committee (later to become ICRP) set limit = 2 mGy/day, ~ 730 mGy/year.
  • 1945 Aug: first atom bombs dropped.
  • 1948: Radiation protection group (US, Canada and UK) reduce permissible human radiation dose by half (to ½ mGy/day, ~ 183 mGy/year)
  • 1950: ICRP reduce recommended limit to 3 mGy/week, ~ 150 mGy/year.
  • 1953 Dec: Eisenhower's atoms for peace UN speech calls for civilian nuclear power
  • 1954 Mar: Rockefeller foundation meet to discuss radiation. Presumably in response to the threat of plentiful atomic power promised by Eisenhower just months earlier. Probably not in response to the Atomic bomb threat; although nuclear tests were increasing during the 1950s, peaking, by number, in 1958 and 1961. In 1954 atomic bomb testing was not huge. 8 tests during the whole year. Rockefeller sponsor NAS BEAR [Biological Effects of Atomic Radiation] committee, pick its membership. Help set its agenda.
  • 1955 Apr: NAS BEAR begin work.
  • 1956 Jun: NAS BEAR publish in NYT calling for no safe radiation dose. Excluding evidence by Ernst Caspari which contradicted no safe dose).
  • 1961: AEC tighten dose limits for occupational exposure to an average of 50 mGy per year after the age of 18 while continuing to suggest that general population exposure levels be restricted to 10% of the occupational levels (5 mGy per year) for individuals. [average U.S. natural exposure from background radiation ~ 4 mGy per year]
  • 1963 Aug: Countries sign global atomic bomb test ban treaty. BEAR scientists congratulate themselves on a job well done: "We made the world a safer place".
  • 1975: I'm told in undergraduate physics class there is "no safe dose" for radiation. That scientists are certain of this. All the evidence tells us. Ernst Caspari is apparently a non person. Real Science says his research never happened. [ I remember so well because I questioned the lecturer on it immediately as it contradicted everything I knew about the response of biological systems to stress ]

PS: All radiation units above were converted to mGy (milli-Gray) to give approximate values for comparison. In reality some limits were set as REMs some as milli-Gray, most as roentgens.

High/medium dose radiation causes cancer

No safe dose: Is not peculiar to radiation. It was decreed that there was "no safe dose" for all carcinogenic substances. From what I can gather, this was a theory first approach to regulation. Better safe than sorry. It is a bit of a nonsense because it cannot be enforced. E.g. Oxygen, which essential to human life. is a DNA mutagen. Some substances are thousands of times more carcinogenic than others. E.g. Aflotoxin made by fungi growing on badly stored nuts or grain is about the most carcinogenic substance known. It may indeed have "no safe dose". Yet that does not mean you get cancer eating some. I loved nuts when I was a child. I must've accidentally eaten bad nuts at least 50 times. Mostly spitting it out but I'm sure some of the "no safe dose" deadliest carcinogen slipped by. I'm still alive and cancer free. DNA mutation and cancer is a complex thing. To cause cancer several mutations are needed and they must be the right ones: leading to a cell growing out-of-control, dividing into new cancerous cells, undetected by our body's immune system. Our body thinks it is still a normal body cell. The wrong mutation will lead to the immune system identifying a bad cell and killing it. Most mutations will be detected and destroyed by our immune system. Unfortunately we have a lot of cells (~ 70 trillion). Each undergoes up to 1 million DNA damage events per day. To start a cancer, it only takes one cell to slip by with the right set of DNA mutations which fool the body's immune system into thinking it's kosher. Most DNA damage events can be repaired by the cell itself, so do not lead to mutations. Single-strand DNA damage is basically repaired. Double-strand DNA damage is also repaired but may not be done so well.

Hormesis to the rescue

In addition there is a hormetic effect. A low dose of a carcinogen may stimulate the immune system to protect the body against cancer. E.g. by increasing autolysis of suspect or damaged cells. This hormetic effect of radiation is thought to kick in at a dose much lower than the 1930s maximum limit. There are a lot of carcinogenic substances about. Oxygen is a DNA mutagen, as well being essential to animal life. We breath in about 500 gram per day of it. It's estimated that up to 3% goes astray in that it is not all used by the right metabolic pathway. That's about a third of a mole per day of wayward oxygen our body must deal with. 2 × 10²³ rogue molecules of oxygen for about 70 trillion human cells; about 3 billion rogue oxygen molecules per human cell. Every day. That must be causing some cancer, some of the time. If the immune system can be stimulated by a hormetic effect, radiation can actually reduce the effect of cancer. Perhaps protecting against harm done by more common / chronic carcinogens as well. It's difficult for me to imagine how oxygen could induce such a (hormetic) effect!, since oxygen is so common. Yet:

Hyperbaric oxygen therapy of humans (100% O2 at 2.5 atm), for instance, induces significant oxidative DNA damage to peripheral blood cells on the first day of therapy but fails to cause damage on subsequent days
-- Oxidative Decay of DNA, by Kenneth B. Beckman and Bruce N. Ames

At moderate to low radiation doses (below 730 mGy/year) the harmful effect of radiation is increased cancer risk. It is a carcinogen. Yet no major illnesses developed among workers after maximum dose limits were imposed in the early 1930s. Because at this level < 2 mGy/day, the hormetic effect of radiation protecting us out-weights the additional harm done by mild radiation exposure. In 1948 / 1950 this exposure level was cut to just a quarter of the 1930s. Then it was cut again to "no safe dose". No scientific studies conclusively show either the lower limit (~ 150 mGy/year) or the zero limit are safer. Scientific studies are inconclusive. Some show barely perceptible increased risk. Some show a clear hormetic effect of less cancer risk.

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