You are correct. Alpha Radiation is the most toxic per amount and you are correct that it is blocked by pretty much anything as it is a particulate.

We probably agree on much more than you realize! :D

-S

That's what I said, it's harmless as long as you don't actively touch it or something...

Wow, this is a real Jimmy Carter moment!:rotfl: Peace in our time.

reactor collant = red hering
 

SO?

Reactor Coolant is not in contact with the U235 enriched material. It's not comtamianted by radiation. It's the same as drinking tap water or bottled water.

He's not drinking water that's been in DIRECT contact with the Uranium

If you leak U235 atoms into that collant water and Ricter Drank that water he would have died long before he died from old age.

Enriched U235 is only 3% and that's enough to make a bomb.

Salmon Run? huh?
 

The Colorado River barely has any water left when it reaches the Coast. There are no salmon running up the Colorado River anymore

Nuclear Energy is not safe and never will be. You forget about the waste byproduct my friend. You can't just ignore the spent fuel and dismiss it like you have.

Nuclear energy is not safe a all. It's very dangerous and has a lethal potential.

Of course the Big Dams will fail sometime in the future and create one of the largest floods of all time.

Nukeclear power is persuasive these days, and maybe one must even argue that the climate bgoals some nations have formulated cannot be acchieved without it. On the othe rhand, reneable energy's potential constantly get underestimated. their major problem is that they will need more time to be installed then we have left - at least having left bwhen listening to the ngermkan government's plans to have significantly reduced CO2 emission at this or that point of time. Some days ago they announced their intention to build 30 offshore windparks in Germany. hat will costs not only much, very much money, but also will not be completed before 2030. But climate goals they have announced for years much earlier, so - the timetable is seriously messed up. And that timer table is just ink on paper anyway. If nature gives us so much time before becoming really angry with us, remains to be seen.

I am undecided on the nuclear energy thing. I was in favour of Germany's decision to leave it behind and shut of nuclear powerplants alltogether. But I meanwhile had to realise that it probably will not work well without these in the forseeable future, and that one nation leaving nuclear energy all alone will make no difference for the world. Nuclear accidents do not stop at borders, and their are reactors in France as well, Britain, and Sitzerland plans to build one right at the border to Germany.

I think the best option is to make as much reduced use of nuclear energy as possible, shut down old plants, and build as few new ones as possible - and for these only using the most safest conctruction principles and technologies known on the market. And the truth is, even if that hurts some patriot's feelings, that not all nations build reactors of comparable security standards.

But we must be aware, that every technology never will be fail-safe, and that even perfect maintenance does not mean at all that some critical thing will not break. A major mess like Chernobyl - but in the middle of europe, in central Germany for example, could change life in the old world forever, and would cut economic wounds from which Europe in today's global and sharp competition would not recover in the forseeable decades.

It makes zero sense to tame this statement by saying the probability is like this or that - when it is takign place, the probability has turned into a solid 100%, and probability calcvulations have the same problem like classic test theory in statistics - they base on the assumption that there is an unlimited or at least very very high number of trials on which these calcualtions base. But there isn't, and even a probabilty of 0.00001 does not mean that you could not have one reactor blowing up per year for the next 10 years. Probability calculations get massively absued these days, and often are used to boost a wanted agenda. It is stupid to take consolation from such calculations.

So let'S make critical use of it, but as limited as possible, and do this exercise as careful as possible. That includes to leave control of safety not to the industry or it'S lobbyists in politics, of course. Independant, unannounced, constant control is absolutely indispensable. Things like the lying policy of the Swedish company after their series of very serious problems lately are unacceptable and should rank as most major crimes like slaughter for example. responsible managers must go to jail - and not just for a shamefully small number for years, but so long that it really hurts badly. the unconditonal cooprtation with the controlling authority must be enforced - with all means. the consequences of a major accident are simply to costly and too bad as if we should accept anything less. Company interests are absolutely and always of just secondary importance here.

In other words - I would not trust any politician talking about responsible use of safe nuclear energy, and security measures.

Which leaves me in a dilemma, of course.

Certain types of U-235 Reactors (Not sure if the majority or not) DO have water come into direct contact with U-235, because the water blocks out the radiation just fine, however, U-238 reactors must use Heavy water, which must be separated from the core because it would make a lot of mass otherwise...

Well, not really. Solar energy and wind energy can both be classified as the safest forms. With them, you don't have to worry about catastrophic and potentially damning meltdowns or the possibility of everything within a 20 mile zone either being vaporized in an instant/radiated to the point of death.

Also, you've got to dispose of the nuclear waste once you accumulate it, which is a tricky and dangerous process.

Where is the possibility of everything in a 20-mile radius being vaporized coming from? Did someone drop a nuclear warhed on the reactor?
Nuclear energy is a lot safer than most people realize. Unfortunately, there is so much unfounded fear that the cost of building and maintaining reactors has skyrocketed ever since that dumb "China Syndrome" movie, primarily because of insurance costs and stupidly redundant numbers of back-up systems.

As far as "disastrous consequences" go let's look at the worst nuclear accident in history, namely "Chernobyl". The initial deleterious effects of this disaster are not cause for lasting concern today, as the contaminated area is relatively small and people even live in the abandoned zone.
This is especially impressive when you consider that it was a Soviet reactor and the Soviets seemed to be unable to do much of anything without suffering a nuclear mishap.
Another common misconception is the likelyhood of a meltdown. You would be surprised how many people think that means the reactor blows up like a nuclear bomb. Not only is this not possible, but a meltdown even in the correct sense of the word is nearly impossible. You would really have to put some effort into making it happen. The fuel rods have to become host to an uncontrolled reaction, which means the control rods, and the emergency control rods, and the manual control rods would all have to fail, which is tricky when you consider that if they lose power or connection with the plant's systems they all go right into the reactor core. Then, the reaction has to be uncontrolled by any means until the rods become hot enough to actually melt through the containment vessel and the ground below it until they reach the water table.
Although technically possible, it is essentially a non-concern.

The greatest danger comes from the reactor core and its containment vessel being breached, or from improper handling of waste. Either of these scenarios is likely to cause only local contamination, and though expensive to clean up, serves as a powerful motivator for companies to prevent that from happening in the first place.

Our main problem is where to put all the nuclear waste. Considering how much waste goes into landfills and the like, when coupled with the very small amount of waste that reactors produce, this is not so much a problem of space as it is of NIMBY. Solution; just store it where nobody lives. Yes, they tried this with the Yucca mountain facility and met with stiff resistance but that sentiment was fueled by irrational fear and an inexplicable love of some obscure desert region's largely useless fauna.

Finally, nuclear power is very economical when compared to "clean" sources. The only potential rival would be hydroelectric power from a dam, and even that requires a tremendous initial investment. Solar and wind power can't even be classified as competitors because of their ridiculous construction and maintenance costs. In addition, all of the above require specific locations and or environmental characteristics, denying them the flexibility of nukes.

Just a few nits to pick until they bleed and scab over. Followed up with bombastic pendantics of more information than a normal person would ever want.

It is important to know the differences between the coolant and the moderator in a nuclear reactor.

The moderator, which in contact with the fuel rods (never in direct contact with the Uranium) serves to slow down the neutrons. (skipping incomprehensible physics) Slower neutrons have an increased chance of causing fission (a good thing). This moderator, which can be a solid (graphite) or a liquid (many formulas) gets very hot and needs to be cooled.

The coolant (which can be a liquid or a gas) is designed to wick away the heat from the critical assembly to include the moderator. Depending on the design of the reactor, the coolant may be radioactive or not (many reactors have staged cooling systems to isolate the radiation). One would not want to drink the primary coolant. Not only is it hot, but tastes like crap and will probably kill you).

Can the moderator and the coolant be the same thing? Yes and no. Depends on the type of reactor.

In a Light Water Reactor, the low enriched 235U reaction is moderated by regular water (H2O). This water also wicks heat away from the critical assembly so it can also be considered a coolant. However in LWRs there needs to be a secondary cooling system (which usually uses water but does not have to) to remove the heat from the moderator. So you would have the water doing double duty of both moderating the reaction and acting as the primary coolant.

One thing to keep in mind is that in a power generating nuclear reactor this heat is the primary product. It needs to be saved and moved to where it can mechanically drive a turbine. Turbines (and the technicians responsible for the running of turbines) get bitchy when radioactive steam is introduced into their systems. One of several reasons for radiological isolation of the coolant systems.


“... DO have water come into direct contact with U-235...”

Strictly speaking the moderator never comes in direct contact with the 235U. The 235U is formed into what is called fuel rods (constructions of Uranium fuel pellets stacked in a specific way inside a metal case called “Cladding”. The purpose of the cladding is to maintain the structural geometry of the fuel stack as well as protecting the Uranium from contact with water. Uranium fuel pellets are like Gremlins. You don’t want to get them wet. They get real bitchy and stop talking to the neutrons.

“... U-238 reactors must use Heavy water”

238U is non fissile. 235U is fissile. Fissile is one of them fancy words meaning capable of maintaining a chain reaction or criticality. Whether a 235U reactor uses light water (H2O) or heavy water (D2O) depends on the enrichment of the 235U. Natural 235U (0.7%) needs heavy water, low enriched 235U (3-5%) needs light water.

So 238U is useless? Not at all

238U is required for the production of Plutonium.

When a 238U atom and a neutron like each other very very much........

238U has a well earned reputation of being greedy when it comes to Neutrons. 235U plays nice with neutrons and when hit with one nicely splits up into chunks, gives off a little heat, and gives back to society less than 3 neutrons on average. These less than three neutrons spread out and contact other atoms of 235U and smack in to them (sorta like a nuclear mosh pit). This is called a Chain Reaction because it is like a chain letter -- if a neutron fails to smack another atom of 235U, it is cursed with bad luck. While the other neutrons who do smack in to an atom of 235U keeps the chain going and is blessed with good luck.

On the other hand the greedy 238U atom is so self centered that if a neutron smacks into it, the 238U absorbs the neutron, gives nothing back (well almost nothing). Feeling pretty proud of it self, the now fat 238U transmogrifies into several other elements finally deciding on 239Pu (Plutonium). This is how you “grow” Pu. You overfeed a 238U atom with neutrons. The problem is that Pu keeps the greed of 238U and keeps absorbing neutrons and growing fatter (240Pu) and fatter (241Pu) and fatter.......

How much you feed your Pu buddy depends on what you want to do with it.

If you want to make Plutonium explosive devices, you want thin trim 239Pu.

If you want to fuel a Plutonium power reactor, then the fatter Pu’s work better.

I was referring to pool reactors, where the Light Water is used as both the moderator, coolant and shield

I never said U-238 was useless, just that it needed to be shielded separately because Heavy Water makes a lousy radiation shield, or so I heard

Damnit, now I'm all confused

A few years one of our nuclear groups briefed an interesting theory...

One of the cleverest ideas for disposal of high level nuclear waste is to inject it in to the molten portion of the earth.

At the bottom of the ocean there are parts that are, for practical purposes bottomless. The bottom is in a constant fluid state sinking down into the various levels of the earth's layers. The very few times we have explored these areas, cameras have shown how fast the geologic currents flow. You can easily see the bottom sink into the "center of the earth".

Anything dropped in this crevasse would sink and be carried into the molten layers of the earth.

The idea is to contain the high level waste in a container (torpedo) strong enough to contain the material for several years (this is not a problem at all. It is storing it for thousands of years that is the tough part).

Every once in a while an unmanned submarine would take a supply of these torpedoes and "shoot" them in to specific locations where the bottom fluid where they would "swallowed" up by the geologic currents. Within minutes/hours the containers would sink into the subsurface currents. A few years later it gets into the molten portions of the earth. Once it gets to the proper subsurface depth the heat and pressure would rupture the container and release the waste. This waste would be diluted and broken down into its elements by the heat and pressure. The elements would become part of the earth but now in a safe, dispersed and isolated state.

This would be the ultimate recycling. Remember that nuclear waste is natural material. It is just in concentrations not normally found on the surface and in states not normally found on the surface. But these states are nothing compared to the incredible pressure and heat in the magma. Literally nothing could survive there before being melted down into it's basic elements.

This idea would take some technology and considerable logistics but it would be one way to get rid of our high level waste instead of burying it on the surface for a few thousand years.

Interesting concept.

My apologies if I implied that you implied that 238U was useless. I just added that information in my response some additional information. Chicks dig guys who know about nuclear reactors...... no I can't back that up. :nope:

Hmm, Interesting

This theory sounds much more feasible than ejecting all the nuclear waste into space

(Which unfortunately, makes me think of all those times I dumped radioactive waste into inhabited systems in Frontier: Elite 2...)