AP McCain calls for building 45 new nuclear reactors

[Cobol74]

Viper I think Jetsetter is saying (please correct me if incorrect):

Go near a nuclear Power Station and your friendly, armed to the teeth with high tech stuff guards, will in a polite and friendly manner blow you MF head off.

My post + the high tech bit.

[Viper007Bond]

Oh.

[Cobol74]

Well I could be wrong.

I know that it is a rare Space Time event but possible. (Quote for Dr Who circa 1971.)

[idk]

Hahaha... i find that sooooo ridiculous. Here in Europe the CO2 discussion is getting worse and worse... many countries are building new nuclear power plants because... with our current technology thats the ONLY way to reduce that CO2 stuff in a noticable amount.
Only here in Germany the former government blackmailed by the greenparty and jittering to get reelected decided to quit nuclear energy and even close down all the powerplants we have by a specific date (which is still in a debate).

All world is building new ones including france directly at our border... just we stupid folks I'd strongly support a policy that counts on nuclear energy. I'd rather live with the very low risk of an accident like never be able to have fun on the road in a car because all fun cars will be all banned because of CO2 emision in very near future (at the specific time that i can afford one) here.

[Cobol74]

We are not quite, yet - and I do not believe that this is the way to go myself - the costs in human life are too horrendous, sorry.

[DTMracer]

I reckon more funding should be put towards nuclear research to perfect it to a point where the accident rate is almost zero. Obviously, nothing in life is ever completely risk free, but the more research we do, the better our understanding will be so that we can design very safe reactors.

[petarkb]

Originally Posted by DTMracer

I reckon more funding should be put towards nuclear research to perfect it to a point where the accident rate is almost zero. Obviously, nothing in life is ever completely risk free, but the more research we do, the better our understanding will be so that we can design very safe reactors.

You mean like an IQ test for the higher-ups? Because Chernobyl was destroyed by idiocy during an experiment, it was not a defective design.

[jetsetter]

it was not a defective design.

Not having a substantial concrete containment vessel is a defect in the design.

* The reactor had a dangerously large positive void coefficient. The void coefficient is a measurement of how the reactor responds to increased steam formation in the water coolant. Most other reactor designs produce less energy as they get hotter, because if the coolant contains steam bubbles, fewer neutrons are slowed down. Faster neutrons are less likely to split uranium atoms, so the reactor produces less power. Chernobyl's RBMK reactor, however, used solid graphite as a neutron moderator to slow down the neutrons, and neutron-absorbing light water to cool the core. Thus neutrons are slowed down even if steam bubbles form in the water. Furthermore, because steam absorbs neutrons much less readily than water, increasing an RBMK reactor's temperature means that more neutrons are able to split uranium atoms, increasing the reactor's power output. This makes the RBMK design very unstable at low power levels, and prone to suddenly increasing energy production to dangerous level if the temperature rises. This was counter-intuitive and unknown to the crew.
* A more significant flaw was in the design of the control rods that are inserted into the reactor to slow down the reaction. In the RBMK reactor design, the control rod end tips were made of graphite and the extenders (the end areas of the control rods above the end tips, measuring 1-metre (3 ft) in length) were hollow and filled with water, while the rest of the rod — the truly functional part which absorbs the neutrons and thereby halts the reaction — was made of boron carbide. With this design, when the rods are initially inserted into the reactor, the graphite ends displace some coolant. This greatly increases the rate of the fission reaction, since graphite is a more potent neutron moderator (a material that enables a nuclear reaction) and also absorbs far fewer neutrons than the boiling light water. Thus for the first few seconds of control rod activation, reactor power output is increased, rather than reduced as desired. This behavior is counter-intuitive and was not known to the reactor operators.
* The water channels run through the core vertically, meaning that the water's temperature increases as it moves up and thus creates a temperature gradient in the core. This effect is exacerbated if the top portion turns completely to steam, since the topmost part of the core is no longer being properly cooled and reactivity greatly increases. (By contrast, the CANDU reactor's water channels run through the core horizontally, with water flowing in opposite directions among adjacent channels. Hence, the core has a much more even temperature distribution.)
* To reduce costs, and because of its large size, the reactor had been constructed with only partial containment. This allowed the radioactive contaminants to escape into the atmosphere after the steam explosion burst the primary pressure vessel.
* The reactor also had been running for over one year, and was storing fission byproducts; these byproducts pushed the reactor towards disaster.
* As the reactor heated up, design flaws caused the reactor vessel to warp and break up, making further insertion of control rods impossible as the heat deformed them.

[petarkb]

Originally Posted by jetsetter

Not having a substantial concrete containment vessel is a defect in the design.

The design might have been hard to operate, but I think lack of proper communication and pressure from the higher-ups was what broke the camel's back.

Originally Posted by http://hyperphysics.phy-astr.gsu.edu/Hbase/nucene/cherno.htm

Chernobyl Chronology

1. The reactor was powered down for a test sequence to determine if one of the turbogenerators could supply power to feedwater pumps until standby diesel generators came on line in the case of a local power failure. The test sequence involved the following dangerous steps

a. Instead of the design based 22-32% full power, the power was inadvertantly lowered to 1% of full power, an extremely unstable situation because of the positive void coefficient. Edwards reports that the operator failed to reprogram the computer to maintain power at 700-1000 MW(t).

b. Essentially all the control rods were pulled out of the core, to the point where they could not shut down the reactor rapidly if needed. This step was taken to get the power back up, but it only reached 7%, still well below the design parameters for the test. The reason the power could not be brought back up was the "xenon trapping" or "xenon poisoning" effect. Xenon is a decay product of I-135 and is a strong neutron absorber which "poisons" the fission reaction. It reaches an equilibrium at normal operating power levels by being "burned away" by neutron absorption and further decay. When the power level was decreased from the 1600 MW level, you had lots of I-135 to decay into xenon, but a small neutron flux with which to burn it away, so it built up rapidly. Excellent description of this by Kress on pg 45. Good one paragraph summary of accident on p46.

c. In order to keep the reactor from automatically shutting down under these conditions, they had to disconnect the emergency core cooling system and several of the automatic scram circuits.

d. All eight cooling water pumps were running at the low power, compared to a normal six even at full power, so there was nearly solid water with almost no void fraction, which increased the vulnerability to any power excursion which produced boiling.

2. The turbogenerator was tripped to initiate the test, which caused the switching off of four of the eight recirculation pumps. (This would have scrammed the reactor if the automatic scram circuit had not been disconnected.)

3. Reduced coolant flow caused voids to form rapidly in the pressure tubes, increasing reactivity because of the positive void coefficient.

4. Within seconds, with rapidly rising power, an emergency manual scram was ordered, but the almost fully withdrawn rods could not insert negative reactivity fast enough because of their slow speed. Also, an unexpected displacement of water from the control rod tubes occurred, further adding to the positive reactivity.

5. The core went to prompt criticality, overheating and shattering fuel rods and flashing the coolant into steam. Fuel channels were ruptured.

6. Steam pressure blew the 1000-ton steel- and cement-filled biologic shield off the top of the reactor, severing all pressure tubes(some 1600 of them) and exposing the hot core to the atmosphere. Edwards says power reached 100 times operating maximum and the explosive force was about 1 ton of TNT.

Soviet scientist Legasov said of the violations of the safety restrictions "It was like airplane pilots experimenting with the engines in flight." The ORNL review says that if the operators had failed to complete the test they could not have repeated it for a year. This probably influenced them to take more risks than normal.

[Spectre]

The design was also stupid in that it didn't have all the fail-safes and deadman-safeties that a Western reactor had to have. For example, in a number of US reactor designs - many of which predate the Chernobyl design - the cooling system is linked to the control rods. If your cooling system loses pressure, the control rods descend or extend automatically because of the loss of pressure. It's a simple mechanical safety. The reactor shuts down.

Disconnect it, and the reactor shuts down anyway via one of the other systems that you *can't* turn off.


On top of all that, as jetsetter mentioned, Chernobyl didn't have anything resembling the enormous concrete containment vessel that is required in conventional US civilian reactor designs. One of those could withstand a small nuclear bomb exploding at contact range.

[chaos386]

Originally Posted by petarkb

The design might have been hard to operate, but I think lack of proper communication and pressure from the higher-ups was what broke the camel's back.

^That's a design failure. Part of designing a plant of any type is making it safely operable by the intended staff. If any part of plant operation is counter-intuitive and/or the plant lacks failsafes, it's a design flaw.

[marcos_eirik]

Here's Discovery channel's documentary on the Chernobyl disaster:

Part 1/6

+ YouTube Video

Part 2/6

+ YouTube Video

Part 3/6

+ YouTube Video

Part 4/6

+ YouTube Video

Part 5/6

+ YouTube Video

Part 6/6

+ YouTube Video

Edit; And History Channel's documentary:

Part 1/3

+ YouTube Video

Part 2/3

+ YouTube Video

Part 3/3

+ YouTube Video

[FATMOUSE]

Also, concrete walls around a reactor can withstand the energy from an F4 Phantom II crashing into it at 480mph.

There's a youtube video.

[AnGuRuSO]

Nuclear reactors are great, they get so much bad press but they really are a pretty damn clean form of energy. A lot of studies have been done to show that mining/transportation of uranium makes nuclear power more expensive and less clean than it may appear.

However new reactors are great

[Shawn]

Originally Posted by Spectre

I should perhaps have said that "As far as the United States was concerned" the Revolution began on that date. Before that, while Iran was technically an ally, the revolution didn't really affect us all that much.

Unfortunately, what the Iranians learned from the embassy incident is that they could twit the US as much as they wanted and the US would do nothing - which is a dangerous lesson to have anyone learn.

Iran is pissed off at the US for no specific reason other than they hate Western hegemony. Things like the US embassy hostage crisis and even older than that, the removal of Reza Shah and appointment of his son as king by the British and Americans are not at all what people are concerned about here today.

When the Islamists came to power here they needed to motivate the people in some way, and blaming everything on hegemony and meddling from Western powers is how they achieved this.

The 1979 Revolution happened for one sole reason, and that was the stupidity and selfishness of the last Shah. He wanted to retain absolute power and viciously silenced even the tiniest bit of dissent... he could have done what other monarchs do these days, and that was gradually give people democracy. He wasn't willing and he got his arse handed to him... by a group more evil than him, but that's another story in itself.

And Spectre, you seem to be somewhat misinformed about this topic. When the hostage crisis happened the Iranian Revolution was over and done with. The situation broke out when the US admitted the Shah into America, briefly, so he could get treatment for his cancer.

The Khomeini regime was already looking for an excuse to totally severe their relationship with the US as I explained above, and this was a good excuse. They were gonna severe their ties one way or other because one of the main reasons for the Revolution was the ever-increasing American influence in Iran. But even as far as the US was concerned, to borrow your own words, the revolution began the moment the Shah departed and Khomeini took over... fundamentalist Islam really never got along with America, in Iran or any other muslim nation. The hostage situation and the total inability of Carter as a politician were just excuses.

Sorry if the discussion has already moved back on topic, I just saw this thread, and it's a little hard to ignore since I'm an Iranian and I'm currently here in Iran.

[petarkb]

Originally Posted by chaos386

^That's a design failure. Part of designing a plant of any type is making it safely operable by the intended staff. If any part of plant operation is counter-intuitive and/or the plant lacks failsafes, it's a design flaw.

OK, so removing all the rods from a reactor that is known to be built to a price is prudent, then? The staff was simply not instructed well enough and that's a management flaw. The design was not flawless*, but it wouldn't have asploded if it had been well-ran.

As for counter-intuitivity, consider this. A powerful rear-wheel drive oversteers if you try to accelerate too soon in a corner. Take your foot sharply off the throttle, and it oversteers even worse. That's definitely counter-intuitive behavior.

Therefore, are all powerful RWD cars defective?

Originally P