Apollo 11 Lunar landing - 40th aniversary

In rec.photo.digital.slr-systems DRS wrote:
"Chris H" wrote in message

In message 4a6ffc56$0$9720$5a62ac22@per-qv1-newsreader-
01.iinet.net.au, DRS writes

[...]

Two accidents due in large part to poor design is not an argument
against nuclear per se. Any fair dinkum analysis of the non-carbon
emitting power sources inevitably bring nuclear into the equation.
Just ask the Germans and the Danes where they get their electricity
when the sun doesn't shine and the wind doesn't blow.
And the French.....

The trouble is that whilst the US is good at making Nuclear weapons it
is not very good at making nuclear power stations. 3 mile island
could very easily have been a Chernobyl.

No, it couldn't. No Western reactor uses positive feedback designs.

A nuclear chain reaction of the kind used in nuclear power stations is
inherently a positive feedback process.

--
Chris Malcolm

"Chris Malcolm" wrote in message

In rec.photo.digital.slr-systems DRS
wrote:
"Chris H" wrote in message


[...]

The trouble is that whilst the US is good at making Nuclear weapons
it is not very good at making nuclear power stations. 3 mile
island could very easily have been a Chernobyl.

No, it couldn't. No Western reactor uses positive feedback designs.

A nuclear chain reaction of the kind used in nuclear power stations is
inherently a positive feedback process.

Which is not what I was talking about and you should know it. The
Chernbobyl nuclear power plant used graphite-tipped control rods. When the
core overheated and the water coolant flashed into steam that graphite
*increased* the nuclear reaction rate as the control rods were inserted. As
the core got hotter more water flashed, etc. It was a positive feedback
loop not possible with Western designs.

In message 4a7179c1$0$9740$5a62ac22@per-qv1-newsreader-
01.iinet.net.au, DRS writes
"Chris Malcolm" wrote in message

In rec.photo.digital.slr-systems DRS
wrote:
"Chris H" wrote in message


[...]

The trouble is that whilst the US is good at making Nuclear weapons
it is not very good at making nuclear power stations. 3 mile
island could very easily have been a Chernobyl.

No, it couldn't. No Western reactor uses positive feedback designs.

A nuclear chain reaction of the kind used in nuclear power stations is
inherently a positive feedback process.

Which is not what I was talking about and you should know it. The
Chernbobyl nuclear power plant used graphite-tipped control rods. When the
core overheated and the water coolant flashed into steam that graphite
*increased* the nuclear reaction rate as the control rods were inserted. As
the core got hotter more water flashed, etc. It was a positive feedback
loop not possible with Western designs.

But different failures are. 3 mile island could have been much worse. As
it was the press blew it up into something worse that it actually was

--
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
\/\/\/\/\ Chris Hills Staffs England /\/\/\/\/
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Chris H wrote:
In message 4a7179c1$0$9740$5a62ac22@per-qv1-newsreader-
01.iinet.net.au, DRS writes
"Chris Malcolm" wrote in message

In rec.photo.digital.slr-systems DRS
wrote:
"Chris H" wrote in message


[...]

The trouble is that whilst the US is good at making Nuclear
weapons it is not very good at making nuclear power stations. 3
mile island could very easily have been a Chernobyl.

No, it couldn't. No Western reactor uses positive feedback
designs.

A nuclear chain reaction of the kind used in nuclear power stations
is inherently a positive feedback process.

Which is not what I was talking about and you should know it. The
Chernbobyl nuclear power plant used graphite-tipped control rods.
When the core overheated and the water coolant flashed into steam
that graphite *increased* the nuclear reaction rate as the control
rods were inserted. As the core got hotter more water flashed, etc.
It was a positive feedback loop not possible with Western designs.

But different failures are. 3 mile island could have been much worse.
As it was the press blew it up into something worse that it actually
was

It could have been much worse but not because of "positive feedback". Nine
seconds into the incident the rods went in and the fission reaction was shut
down. The major problems were the result of an operator mistakenly turning
off two of the primary coolant pumps an hour or so into the incident.

By the way, a fission reactor only operates on "positive feedback" when it
is run at a level above criticality, below criticality there is no "positive
feedback".

DRS wrote:

Which is not what I was talking about and you should know it. The
Chernbobyl nuclear power plant used graphite-tipped control rods. When the
core overheated and the water coolant flashed into steam that graphite
*increased* the nuclear reaction rate as the control rods were inserted. As
the core got hotter more water flashed, etc. It was a positive feedback
loop not possible with Western designs.

It is not possible in some western designs. Similar problems are in many of
the reactors that use control rods to slow down neutrons. After the Chalk River
near meltdown (Graphite control rods) in the mid 50's AECL started
designing CANDO reactors that used heavy water to moderate the reactions.
When the water boils or disappears the reaction essentially stops after a
burst of high energy neutrons. The primary reason for heavy water is this fail
safe property.


w..

In rec.photo.digital.slr-systems J. Clarke wrote:
Chris H wrote:
In message 4a7179c1$0$9740$5a62ac22@per-qv1-newsreader-
01.iinet.net.au, DRS writes
"Chris Malcolm" wrote in message

In rec.photo.digital.slr-systems DRS
wrote:
"Chris H" wrote in message


[...]

The trouble is that whilst the US is good at making Nuclear
weapons it is not very good at making nuclear power stations. 3
mile island could very easily have been a Chernobyl.

No, it couldn't. No Western reactor uses positive feedback
designs.

A nuclear chain reaction of the kind used in nuclear power stations
is inherently a positive feedback process.

Which is not what I was talking about and you should know it. The
Chernbobyl nuclear power plant used graphite-tipped control rods.
When the core overheated and the water coolant flashed into steam
that graphite *increased* the nuclear reaction rate as the control
rods were inserted. As the core got hotter more water flashed, etc.
It was a positive feedback loop not possible with Western designs.

But different failures are. 3 mile island could have been much worse.
As it was the press blew it up into something worse that it actually
was

It could have been much worse but not because of "positive feedback". Nine
seconds into the incident the rods went in and the fission reaction was shut
down. The major problems were the result of an operator mistakenly turning
off two of the primary coolant pumps an hour or so into the incident.

By the way, a fission reactor only operates on "positive feedback" when it
is run at a level above criticality, below criticality there is no "positive
feedback".

There is always positive feedback. Below criticality the gain is less
than one, past criticality the gain is greater than one.

--
Chris Malcolm