...Nuclear MELTDOWN in Japan, is US Threatened???

"Harold Burton" wrote in message
...
In article ,
Sylvia Else wrote:

On 13/03/2011 2:38 AM, Jonathan wrote:
Look at this explosion at 47 seconds into the video.
A violent hydrogen explosion, demolishing such a
heavily reinforced containment building, must have
been the result of a badly overheated reactor.


A claim that appears to be wrong in almost every detail.



What do you expect from an idiot like Jonathan?


That statement is correct in every detail. Does anyone
read the news?

On Mar 12, 4:41*pm, Robert Clark wrote:


Battle to stabilise earthquake reactors
12 March 2011.
UPDATE 6: 10.15 am GMT
"Three of Fukushima Daiichi's six reactors were in operation when
yesterday's quake hit, at which point they shut down automatically and
commenced removal of residual heat with the help of emergency diesel
generators. These suddenly stopped about an hour later, and this has
been put down to tsunami flooding by the International Atomic Energy
Agency (IAEA).
"The loss of the diesels led the plant owners Tokyo Electric Power
Company (Tepco) to immediately notify the government of a technical
emergency situation, which allows officials to take additional
precautionary measures.
Even now, the primary focus of work at the site remains to connect
enough portable power modules to fully replace the diesels and enable
the full operation of cooling systems."
http://www.world-nuclear-news.org/RS...e_earthquake_r...

*If the main problem is just getting enough portable power there then
there are portable gas turbine generators capable of putting out 10's
of megawatts. You could also use the power from a nuclear aircraft
carrier at a power range of 200 megawatts, though there might concern
about bringing it off shore in a zone subject to tsunamis.


Nuclear powered submarines would provide another means of providing
portable power for the reactor cooling systems. The American Seawolf
submarine uses 40 megawatt reactors and the Russian Akula class
submarines operate at 190 megawatts.
There would be less concern for tsunamis for submarines if operated
off shore. You would still need likely to be hundreds of yards off
shore for their required depth to operate. Then you would also need
sufficient cabling to cover that distance.


Bob Clark

On Mar 12, 7:41*pm, Sylvia Else wrote:
On 13/03/2011 2:38 AM, Jonathan wrote:

Look at this explosion at *47 seconds into the video.
A violent hydrogen explosion, demolishing such a
heavily reinforced containment building, must have
been the result of a badly overheated reactor.

A claim that appears to be wrong in almost every detail.

Sadly, a public perception that the reactor suffered a catastrophic
meltdown will probably persist, and spoil the chances of nuclear
reactors being built in the future. Since power is still required, coal
will be used instead.

Sylvia,

well japan now admits the pit at least partially melted down.......

"Fred J. McCall" wrote in message
...
bob haller wrote:

On Mar 12, 7:41 pm, Sylvia Else wrote:
On 13/03/2011 2:38 AM, Jonathan wrote:

Look at this explosion at 47 seconds into the video.
A violent hydrogen explosion, demolishing such a
heavily reinforced containment building, must have
been the result of a badly overheated reactor.

A claim that appears to be wrong in almost every detail.

Sadly, a public perception that the reactor suffered a catastrophic
meltdown will probably persist, and spoil the chances of nuclear
reactors being built in the future. Since power is still required, coal
will be used instead.


well japan now admits the pit at least partially melted down.......


Reactors don't have "pits".


You forgot to mention it might've melted in a direction
other than exactly...down. (sarcasm)

The whole point of this thread is the distinct lack of information
due to the level of destruction from the earthquakes and tsunami
which hit the area. Combined with a short timeline for any fallout
to make it to the US.

This is a worst case disaster, and it's entirely sensible to
assume the worst case damage happened until we know
differently.

Ignorance is not always bliss.




--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson

Sadly, a public perception that the reactor suffered a catastrophic
meltdown will probably persist, and spoil the chances of nuclear
reactors being built in the future. Since power is still required, coal
will be used instead.

Sylvia,

Joe liberman on face the Nation today called for a moratorium on any
new nuke plants till this is sorted out, in addition 23 US plants are
like the japanese plants.

at least 2 plants and possibly 3 are in meltdown...

On Mar 12, 8:00*pm, "Androcles"
wrote:
"Sylvia Else" wrote in message

...
| On 13/03/2011 2:38 AM, Jonathan wrote:
| Look at this explosion at *47 seconds into the video.
| A violent hydrogen explosion, demolishing such a
| heavily reinforced containment building, must have
| been the result of a badly overheated reactor.
|
| A claim that appears to be wrong in almost every detail.
|
| Sadly, a public perception that the reactor suffered a catastrophic
| meltdown will probably persist, and spoil the chances of nuclear
| reactors being built in the future. Since power is still required, coal
| will be used instead.
|
The reactor suffered a catastrophic earthquake in a region known to
be prone to catastrophic earthquakes. And where did this "hydrogen"
come from to produce a chemical reaction with oxygen, rather than
high pressure steam? Hype hype hype hydrogen bad, hydrogen bombs
and Hindenbergs. Green good.
An earthquake is going to hit Los Angeles. Are they rushing to leave?
No, of course not, they haven't been discovered as great movie stars
yet. But when it does, please help, we need your money. Lots of money.

the hydrogen gas came from the overheated reactor thats now confirmed
in at least partial meltdown.

historically japan hasnt been honest about nuclear accidents,and
besides they dnt want to cause additional panic

On Sun, 13 Mar 2011 07:49:28 -0700 (PDT), bob haller wrote:

Sadly, a public perception that the reactor suffered a catastrophic
meltdown will probably persist, and spoil the chances of nuclear
reactors being built in the future. Since power is still required, coal
will be used instead.

Sylvia,

Joe liberman on face the Nation today called for a moratorium on any
new nuke plants till this is sorted out, in addition 23 US plants are
like the japanese plants.

at least 2 plants and possibly 3 are in meltdown...

A politician called for less action, more study. You needed to watch a
"news" program to learn that? Does it matter which one said it?

How much progress was encouraged by a politician putting the brakes on
in 1979?

The news says "23 US plants are like the japanese plants." It makes a
scary sound bite. In what ways are they "like the japanese plants?"

Are they situated near an 8+ magnitude earthquake?

You want to stop burning fossil fuels (with their emission of evil
CO2), and reduce dependence on foreign oil? Build nuclear power
plants.

Compare the size of the smoke plume at the start of this video
to the point before the explosion at 47 seconds.
The smoke plume grows by some four times in size
in just 40 seconds. Then bang! It fits the worst case scenario
sequence cited below. And the govt statement a pipe burst.
http://www.youtube.com/watch?v=LvC4WQrQwTs

Fukushima Reactor

This reactor is a Boiling Water Reactor (BWR), an early BWR mark 2
with the earliest mark 1 outer containment. Built in 1967. Most reactors
today are Pressurized Water Reactors (PWR). And btw, a BWR doesn't
have top mounted control rods which automatically fall if power is lost.
They're bottom mounted and hydraulically inserted. And it may be the
large suppression pools described below they're trying to fill with
sea-water now I would guess. And it should be noted, below it states
the outer containment building is designed to ...contain...a meltdown.

List of BWR's
http://en.wikipedia.org/wiki/List_of_BWRs


Safety Systems

A BWR is similar to a Pressurized Water Reactor (PWR) in that the reactor
will continue to produce heat even after the fission reactions have stopped,
which could make a core damage incident possible if there were not several
redundant safety features built into the design of the reactor.

BWRs generally have N-2 redundancy on their major safety-related
systems, which normally consist of four "trains" of components. This
generally means that up to two of the four components of a safety system can
fail and the system will still perform if called upon.
http://en.wikipedia.org/wiki/Boiling_Water_Reactor



From Wiki....

Boiling water reactors

In a BWR, the containment strategy is a bit different. A BWR's containment
consists of a drywell where the reactor and associated cooling equipment is
located and a wetwell. The drywell is much smaller than a PWR containment
and plays a larger role. During the theoretical leakage design basis
accident the reactor coolant flashes to steam in the drywell, pressurizing
it rapidly. Vent pipes or tubes from the drywell direct the steam below the
water level maintained in the wetwell (also known as a torus or suppression
pool), condensing the steam, limiting the pressure ultimately reached. Both
the drywell and the wetwell are enclosed by a secondary containment
building, maintained at a slight sub-atmospheric or negative pressure during
normal operation and refueling operations. The containment designs are
referred to by the names Mark I (oldest; drywell/torus), Mark II, and Mark
III (newest). All three types house also use the large body of water in the
suppression pools to quench steam released from the reactor system during
transients.

Design and testing requirements

In the event of a worst-case emergency, called a "design basis accident" in
NRC regulations, the containment is designed to seal off and contain a
meltdown. Redundant systems are installed to prevent a meltdown, but as a
matter of policy, one is assumed to occur and thus the requirement for a
containment building. For design purposes, the reactor vessel's piping is
assumed to be breached, causing a "LOCA" (loss Of coolant accident) where
the water in the reactor vessel is released to the atmosphere inside the
containment and flashes into steam. The resulting pressure increase inside
the containment, which is designed to withstand the pressure, triggers
containment sprays ("dousing sprays") to turn on to condense the steam and
thus reduce the pressure. A SCRAM ("neutronic trip") initiates very shortly
after the break occurs. The safety systems close non-essential lines into
the air-tight containment by shutting the isolation valves. Emergency Core
Cooling Systems are quickly turned on to cool the fuel and prevent it from
melting.

http://en.wikipedia.org/wiki/Containment_building


Disadvantages (BWR)

a.. Complex calculations for managing consumption of nuclear fuel during
operation due to "two phase (water and steam) fluid flow" in the upper part
of the core. This requires more instrumentation in the reactor core. The
innovation of computers, however, makes this less of an issue.

b.. Much larger pressure vessel than for a PWR of similar power, with
correspondingly higher cost. (However, the overall cost is reduced because a
modern BWR has no main steam generators and associated piping.)

c.. Contamination of the turbine by short-lived activation products. This
means that shielding and access control around the steam turbine are
required during normal operations due to the radiation levels arising from
the steam entering directly from the reactor core. This is a moderately
minor concern, as most of the radiation flux is due to Nitrogen - 16, which
has a half-life measured in seconds, allowing the turbine chamber to be
entered into within minutes of shutdown.

d.. Though the present fleet of BWRs are said to be less likely to suffer
core damage from the "1 in 100,000 reactor-year" limiting fault than the
present fleet of PWRs are (due to increased ECCS robustness and redundancy)
there have been concerns raised about the pressure containment ability of
the as-built, unmodified Mark I containment - that such may be insufficient
to contain pressures generated by a limiting fault combined with complete
ECCS failure that results in extremely severe core damage. In this double
failure scenario, assumed to be extremely unlikely prior to the Fukushima I
nuclear incident, an unmodified Mark I containment can allow some degree of
radioactive release to occur. This is supposed to be mitigated by the
modification of the Mark I containment; namely, the addition of an outgas
stack system that, if containment pressure exceeds critical setpoints, is
supposed to allow the orderly discharge of pressurizing gasses after the
gasses pass through activated carbon filters designed to trap
radionuclides[citation needed].

e.. Control rods are inserted from below for current BWR designs. There
are two available hydraulic power sources that can drive the control rods
into the core for a BWR under emergency conditions. There is a dedicated
high pressure hydraulic accumulator and also the pressure inside of the
reactor pressure vessel available to each control rod. Either the dedicated
accumulator (one per rod) or reactor pressure is capable of fully inserting
each rod. Most other reactor types use top entry control rods that are held
up in the withdrawn position by electromagnets, causing them to fall into
the reactor by gravity if power is lost.
http://en.wikipedia.org/wiki/Boiling_Water_Reactor

On Sun, 13 Mar 2011 12:30:55 -0400, Jonathan wrote:


Compare the size of the smoke plume at the start of this video
to the point before the explosion at 47 seconds.
The smoke plume grows by some four times in size
in just 40 seconds. Then bang! It fits the worst case scenario
sequence cited below. And the govt statement a pipe burst.
http://www.youtube.com/watch?v=LvC4WQrQwTs

So your point is the government hasn't told all? Probably not.

The "worst case" hasn't happened. Saying it has is hype.


Fukushima Reactor

This reactor is a Boiling Water Reactor (BWR), an early BWR mark 2
with the earliest mark 1 outer containment. Built in 1967. Most reactors
today are Pressurized Water Reactors (PWR). And btw, a BWR doesn't
have top mounted control rods which automatically fall if power is lost.
They're bottom mounted and hydraulically inserted. And it may be the
large suppression pools described below they're trying to fill with
sea-water now I would guess. And it should be noted, below it states
the outer containment building is designed to ...contain...a meltdown.

Hence, the name, *containment* building. You don't want them to build
nukes in a building that would do this?

Snip Wiki quotes.

"Jacob" wrote in message
...
On Sun, 13 Mar 2011 12:30:55 -0400, Jonathan wrote:


Compare the size of the smoke plume at the start of this video
to the point before the explosion at 47 seconds.
The smoke plume grows by some four times in size
in just 40 seconds. Then bang! It fits the worst case scenario
sequence cited below. And the govt statement a pipe burst.
http://www.youtube.com/watch?v=LvC4WQrQwTs

So your point is the government hasn't told all? Probably not.

The "worst case" hasn't happened. Saying it has is hype.


Fukushima Reactor

This reactor is a Boiling Water Reactor (BWR), an early BWR mark 2
with the earliest mark 1 outer containment. Built in 1967. Most reactors
today are Pressurized Water Reactors (PWR). And btw, a BWR doesn't
have top mounted control rods which automatically fall if power is lost.
They're bottom mounted and hydraulically inserted. And it may be the
large suppression pools described below they're trying to fill with
sea-water now I would guess. And it should be noted, below it states
the outer containment building is designed to ...contain...a meltdown.

Hence, the name, *containment* building. You don't want them to build
nukes in a building that would do this?


The failure scenario design assumption is that a coolant pile to the steel
reactor containment vessel broke, causing a melt-down and pressurizing
the outer concrete containment building. But that outer building should
survive even in this worst case. But it appears this early version outer
building didn't have the added safety systems which would vent and filter
the outer building when the pressure built up.

It appears this is the worst case, in terms of level of accident /and/
lack of safety systems.



Snip Wiki quotes.