China suspends approvals for new nuclear plants

[Lankan Ranger]

China suspends approvals for new nuclear plants

China has suspended the approval process for nuclear power stations so that safety standards can be revised after explosions at a Japanese plant, according to Wednesday's executive meeting of the State Council, or the Cabinet.

The State Council has required relevant departments to do safety checks at existing plants, according to a statement released after the meeting, which was presided over by Premier Wen Jiabao.

The statement said all reactors in operation in China are safe and the country remains unaffected by radioactive leakages following explosions at Japan's Fukushima Daiichi nuclear plant which was crippled by Friday's 9.0-magnitude quake and ensuing tsunami.

The radioactive leakages won't affect public health in China since they are diluted by the air and sea, the statement said, citing nuclear experts.

"Safety is our top priority in developing nuclear power plants," the State Council said in the statement, calling for a comprehensive safety check and enhanced management over existing plants.

Before the revised safety standards are approved, all new nuclear power plants, including pre-construction works, should be suspended, according to the statement.

China has six nuclear power plants in operation, which are located along the country's eastern and southern coasts.

The State Council also required the country's environmental regulator, the National Nuclear Safety Administration, to step up monitoring of radioactive substances and issue alerts timely, said the statement.

On March 12, the National Nuclear Safety Administration, under China's Ministry of Environmental Protection, began nationwide radiation monitoring, with results released on its official website every day.

Early in the day another fire broke out at the crippled Fukushima Daiichi nuclear power plant, triggering fear in Tokyo and international alarm. Workers withdrew briefly because of surging radiation levels and a helicopter failed to drop water on the most troubled reactor.

The statement also said that China would continue help Japanese authorities to move Chinese citizens in Japan to safety.

China suspends approvals for new nuclear plants

 

[Ammyy]

Japan crises push whole world to think again about nuclear power plants

 

[oct605032048]

I'm still support the idea of N-power. After all these decades there are only 3 severer (including the recent one) accidents about nuclear power plants. Radiation do not do more harm than dangerous chemical plants or refineries after earthquake. Plus the reactors in Fukushima is an old one, under operation for 30 years, with obsolete technology which make it far more vulnerable than the new nuclear plants.

 

[StingRoy]

I'm still support the idea of N-power. After all these decades there are only 3 severer (including the recent one) accidents about nuclear power plants. Radiation do not do more harm than dangerous chemical plants or refineries after earthquake. Plus the reactors in Fukushima is an old one, under operation for 30 years, with obsolete technology which make it far more vulnerable than the new nuclear plants.

Agree on your second point about the latest technology being used in the newer plants, but not with your first point. Nuclear accidents can have their effects for many generations, whereas a conventional power plant will have its effects only on the ones who are working in the plant itself. I don't think I need to highlight the dangers of nuclear radiation here, but I guess you get my point.

 

[below_freezing]

Agree on your second point about the latest technology being used in the newer plants, but not with your first point. Nuclear accidents can have their effects for many generations, whereas a conventional power plant will have its effects only on the ones who are working in the plant itself. I don't think I need to highlight the dangers of nuclear radiation here, but I guess you get my point.

Disagree. An oil refinery that explodes will leave persistant organic pollutants in the soil. These form not only from the oil itself but also during the explosion. These things react with DNA and cause all sorts of damage, from relatively "easily" repaired base cutting to severe damage like interlinking of DNA and double stranded breaks. They are highly cytotoxic, are magnified in the food chain and have effects for generations. Look at what Agent Orange did in Vietnam, then you'd know.

I am doing my graduating design project on a selective drug delivery system for just this sort of compound as a cancer treatment. With drug delivery systems, it's better to use the most cytotoxic drug you can get, and these were some of my prime candidates though I settled on a proven drug later.

 

[CardSharp]

This is human nature. Why would nuclear power be more dangerous after Fukushima than before? It is like how the local police will put up fencing on a bridge immediately after someone commits suicide there.

They have a saying in the US, "close the barn door after the horse is gone" this whole nuke thing is exactly that.

 

[CardSharp]

Disagree. An oil refinery that explodes will leave persistant organic pollutants in the soil. These form not only from the oil itself but also during the explosion. These things react with DNA and cause all sorts of damage, from relatively "easily" repaired base cutting to severe damage like interlinking of DNA and double stranded breaks. They are highly cytotoxic, are magnified in the food chain and have effects for generations. Look at what Agent Orange did in Vietnam, then you'd know.

I am doing my graduating design project on a selective drug delivery system for just this sort of compound as a cancer treatment. With drug delivery systems, it's better to use the most cytotoxic drug you can get, and these were some of my prime candidates though I settled on a proven drug later.

Oh yeah I'm in a chemistry/pharma program, and just did a presentation on delivery of siRNA as a drug.

 

[below_freezing]

Oh yeah I'm in a chemistry/pharma program, and just did a presentation on delivery of siRNA as a drug.

What did you use as your delivery agent? Was it selective or not? Did you have to take economic factors into account?

I've never considered siRNA or any biologicals due to cost since my side is more towards engineering and my biology understanding is quite limited. my design is on self assembled, folic acid functionalized block copolymer nanospheres with dissolved camptothecin as a chemotherapy agent. cheap, low number of steps in processing, theoretically effective due to camptothecin causing irreparable double stranded breaks. the limitation to using camptothecin directly, i.e. hydrolytic instability and unselective, severe toxicity, are completely solved. just need to run a few experiments to confirm/deny the theory.

 

[StingRoy]

Disagree. An oil refinery that explodes will leave persistant organic pollutants in the soil. These form not only from the oil itself but also during the explosion. These things react with DNA and cause all sorts of damage, from relatively "easily" repaired base cutting to severe damage like interlinking of DNA and double stranded breaks. They are highly cytotoxic, are magnified in the food chain and have effects for generations. Look at what Agent Orange did in Vietnam, then you'd know.

Thanks for the explanation, but I was comparing between a nuclear power plant and a conventional coal based power plant. I agree on the dangers of an oil refinery disaster as you have mentioned. I am for the nuclear plants as long as they are atleast 50 miles away from any human settlements. So that in case of a mishap, the impact on the people and the local economy is not huge.

 

[CardSharp]

What did you use as your delivery agent? Was it selective or not? Did you have to take economic factors into account?

There's different ways of preventing short double stranded DNA from being broken down usually by functionality them so they are stable for a reasonable amount of time. The therapy is still very much theoretical and no one's commercialized it yet, but when they do they can pretty much turn any gene on and off by designing different sequences of RNAi.

I've never considered siRNA or any biologicals due to cost since my side is more towards engineering and my biology understanding is quite limited. my design is on self assembled, folic acid functionalized block copolymer nanospheres with dissolved camptothecin as a chemotherapy agent. cheap, low number of steps in processing, theoretically effective due to camptothecin causing irreparable double stranded breaks. the limitation to using camptothecin directly, i.e. hydrolytic instability and unselective, severe toxicity, are completely solved. just need to run a few experiments to confirm/deny the theory.

How are you planning to target the drug to disease cells?

 

[below_freezing]

There's different ways of preventing short double stranded DNA from being broken down usually by functionality them so they are stable for a reasonable amount of time. The therapy is still very much theoretical and no one's commercialized it yet, but when they do they can pretty much turn any gene on and off by designing different sequences of RNAi.



How are you planning to target the drug to disease cells?

block copolymers show the amazing property of spontaneous phase separation in both melt and solution phase. if one "block" of the polymer is polar, such as polyethylene oxide, and the other part is nonpolar, such as polycaprolactone, in water solution and at temperatures above the glass transition temperature the polar polymers will spontaneously assemble to the outside of a particle, and the nonpolar parts will be packed to the inside. the other amazing property of polyethylene oxide is its OH group at the end of the polymer chain. this can be bonded with FOLIC ACID, whose receptor is OVEREXPRESSED in all tumor cells.

So, the basic process is theoretically: make functionalized polyethylene oxide, then make bulk copolymer, dissolve camptothecin in CH2Cl2, add the copolymer melt, the nonpolar polymers are exposed to the surface, camptothecin diffuses in according to the nonsteady state diffusion equation.

if we assume the concentration of camptothecin remains constant in solution (a rough estimate but it's the easiest to solve mathematically) this has a special boundary condition (constant concentration at surface) which gives it the unique solution: deltaCx/deltaCsurface = 1-(errorfunction)(x/2*sqrtDt) where t is time, deltaCx is the change in concentration at depth x, x is the depth of diffusion, Csurface is the constant concentration at surface and D is the diffusivity. we can selectively dose each nanoparticle depending on the time it spends in solution.

add heat to evaporate CH2Cl2, melt again, dissolve in water, the hydrophilic parts move to the surface, trapping the hydrophobic polymers and the camptothecin inside. the diffusivity D of camptothecin decreases significantly in polar solution such as the polyethylene oxide+folic acid.

administer in water solution to a culture of both normal and tumor cells. hopefully, the tumor cells die before normal ones. the folic acid should make the nanoparticles selectively bind to the tumor cells, and because i've selected biodegradable polymers, once absorbed by the cells, they will dissolve due to hydrolysis action, releasing camptothecin inside the cell and killing it.

 

[CardSharp]

this can be bonded with FOLIC ACID, whose receptor is OVEREXPRESSED in all tumor cells.

add heat to evaporate CH2Cl2, melt again, dissolve in water, the hydrophilic parts move to the surface, trapping the hydrophobic polymers and the camptothecin inside. the diffusivity of camptothecin decreases significantly in polar solution such as the polyethylene oxide+folic acid.

So I understand, the bulk property of these nanospheres are polar (since that is the exposed side)?

 

[below_freezing]

So I understand, the bulk property of these nanospheres are polar (since that is the exposed side)?

yes. the surface property is polar. the polyethylene oxide is the polar molecule, and it is able to be bonded with folic acid. because folic acid is a water soluble B-vitamin, it should preferable remain on the outside, allowing it to bind to receptors.

hopefully the plan works, i'm still at the theoretical step, and still need to look up literature at how to actually make it.

-------

way off topic already, haha...

 

[CardSharp]

yes. the surface property is polar. the polyethylene oxide is the polar molecule, and it is able to be bonded with folic acid. because folic acid is a water soluble B-vitamin, it should preferable remain on the outside, allowing it to bind to receptors.

hopefully the plan works, i'm still at the theoretical step, and still need to look up literature at how to actually make it.

-------

way off topic already, haha...

Once the receptors bind are you sure of an endocytosis mechanism for getting through the membrane? Because a large polar nano-sphere is not going to diffuse at a rate sufficient pharmacokinetically.


If not you might want to consider functionalizing the nanosphere with cell perpetrating peptide. these are well known to work with Clathrin-coated vesicles mechanism for endocytosis and are a hot area of drug delivery research.

 

[below_freezing]

Once the receptors bind are you sure of an endocytosis mechanism for getting through the membrane? Because a large polar nano-sphere is not going to diffuse at a rate sufficient pharmacokinetically.


If not you might want to consider functionalizing the nanosphere with cell perpetrating peptide. these are well known to work with Clathrin-coated vesicles mechanism for endocytosis and are a hot area of drug delivery research.

thanks for the help. I don't know whether they will actually go into the cell. My theory is that it doesn't matter. at the surface, assuming the size of the nanoparticle is small compared to the cell, about half the camptothecin will just diffuse across the membrane just because of short diffusion distances, and remain stable for long enough to kill the cell, while the rest are washed away in the bloodstream. this can't be tested in a culture, and i don't have animal access.

Cell penetrating peptide seems interesting. I need to keep costs down though, since I have to actually experimentally verify it.