Ukraine nuke shutdown...

[Don Y]

OK, I\'ll imagine there are some energy needs that the plant couldn\'t
self satisfy when disconnected from their grid. So, reconnection
enabled them to shutdown the remaining active reactor:
\"preparations are under way for its cooling and transfer to a cold state\"

But, how does that reduce the risk of \"a nuclear disaster\"? The
plant hasn\'t been decommissioned so fissile material still remains
on the premises. Or, is it just the fact that the *pressure* has
been reduced thereby making venting of radiation less likely in
the event of a containment breach (e.g., due to exploding ordinance)?

<https://www.nuclear-power.com/nuclear-power/reactor-physics/reactor-operation/reactor-cooling/>

I.e., with the reactor in \"a cold state\", does it cease to be an issue on
the battlefield?

 

[Martin Brown]

On 11/09/2022 09:52, Don Y wrote:

OK, I\'ll imagine there are some energy needs that the plant couldn\'t
self satisfy when disconnected from their grid.  So, reconnection
enabled them to shutdown the remaining active reactor:
\"preparations are under way for its cooling and transfer to a cold state\"

But, how does that reduce the risk of \"a nuclear disaster\"?  The
plant hasn\'t been decommissioned so fissile material still remains
on the premises.  Or, is it just the fact that the *pressure* has
been reduced thereby making venting of radiation less likely in
the event of a containment breach (e.g., due to exploding ordinance)?

It is more that operational nuclear reactors need ancillary power
available to run just in case they have to shutdown. The coolant pumps
must run for a considerable time afterwards otherwise you can get a TMI
or worse a Chernobyl style bang.

The core remains thermally hot for quite a while after you do a quick
shutdown. Plenty of short lived fission product radioisotopes still
merrily decaying in there on timescales of hours and days.

Snag is that without the pumps moving that heat out of the core it is
far too easy for stagnation to take the core coolant to boiling point
and a massive internal pressure increase. Very bad thing...

https://www.nuclear-power.com/nuclear-power/reactor-physics/reactor-operation/reactor-cooling/

I.e., with the reactor in \"a cold state\", does it cease to be an issue on
the battlefield?

Once it has cooled down enough you don\'t need to be running the coolant
pumps full bore and the amount of power needed is within what emergency
backup generators can supply. ISTR most have two independent grid
connections so that cooling can be maintained even if one link fails.
That\'s how its done in the UK anyway. I don\'t think anyone considered
the possibility of having a full scale war raging round a nuclear plant.

I think the reactor containment is supposed to be good enough to survive
everything except a deliberate direct hit with the right sort of armour
piercing ordinance. We may yet find out if that really is the case.

--
Regards,
Martin Brown

 

[Don Y]

On 9/12/2022 1:34 AM, Martin Brown wrote:

Once it has cooled down enough you don\'t need to be running the coolant pumps
full bore and the amount of power needed is within what emergency backup
generators can supply. ISTR most have two independent grid connections so that
cooling can be maintained even if one link fails. That\'s how its done in the UK
anyway. I don\'t think anyone considered the possibility of having a full scale
war raging round a nuclear plant.

^^^^ this

I think the reactor containment is supposed to be good enough to survive
everything except a deliberate direct hit with the right sort of armour
piercing ordinance. We may yet find out if that really is the case.

Much (all?) infrastructure is designed to address *accidents*,
not malevolent actors. And, even so, often not very well
(\"Who\'da thought a tsunami would flood the generators/pumps located
in the basement?!\")

If the pumps must continue in perpetuity (even when \"cold\"), one has to wonder
how vulnerable *they* are to being compromised. And, with \"repair crews\" not
just a phone call away...

 

[Fred Bloggs]

On Monday, September 12, 2022 at 5:08:19 AM UTC-4, Don Y wrote:

On 9/12/2022 1:34 AM, Martin Brown wrote:
Once it has cooled down enough you don\'t need to be running the coolant pumps
full bore and the amount of power needed is within what emergency backup
generators can supply. ISTR most have two independent grid connections so that
cooling can be maintained even if one link fails. That\'s how its done in the UK
anyway. I don\'t think anyone considered the possibility of having a full scale
war raging round a nuclear plant.
^^^^ this
I think the reactor containment is supposed to be good enough to survive
everything except a deliberate direct hit with the right sort of armour
piercing ordinance. We may yet find out if that really is the case.
Much (all?) infrastructure is designed to address *accidents*,
not malevolent actors. And, even so, often not very well
(\"Who\'da thought a tsunami would flood the generators/pumps located
in the basement?!\")

If the pumps must continue in perpetuity (even when \"cold\"), one has to wonder
how vulnerable *they* are to being compromised. And, with \"repair crews\" not
just a phone call away...

It\'s not reactor, it\'s reactors, this place has 6. They already shut 5 of the 6 down into \"cold state\" and the sixth was kept operational to generate enough electricity to power its own cooling system as well as maintenance cooling for the cold state reactors. They referred to this mode of operation as \"island mode.\" As of Saturday they restored the Ukraine national grid power to the plant site enabling them to initiate shutdown of the 6th reactor into the cold state, using the external grid to power the requisite cooling loads. They say the shut down is a 30 hour process, so it should be in cold state by now. Having all the reactors now in the cold state has eliminated any chance for a Chernobyl type of disaster. And the cold state maintenance cooling would be a light load for the auxiliary power generation in the event it\'s ever needed. Underloading the generations should mean the fuel consumption is greatly reduced, one would think, so it would be less of a crisis to keep them fully fueled.
Of course the media is greatly disappointed and scrambling to find some other story to shock and awe the populace, which is all about viewership and charging top dollar for advertisements.

 

[Don Y]

On 9/12/2022 2:38 AM, Fred Bloggs wrote:

On Monday, September 12, 2022 at 5:08:19 AM UTC-4, Don Y wrote:
On 9/12/2022 1:34 AM, Martin Brown wrote:
Once it has cooled down enough you don\'t need to be running the coolant
pumps full bore and the amount of power needed is within what emergency
backup generators can supply. ISTR most have two independent grid
connections so that cooling can be maintained even if one link fails.
That\'s how its done in the UK anyway. I don\'t think anyone considered
the possibility of having a full scale war raging round a nuclear
plant.
^^^^ this
I think the reactor containment is supposed to be good enough to
survive everything except a deliberate direct hit with the right sort of
armour piercing ordinance. We may yet find out if that really is the
case.
Much (all?) infrastructure is designed to address *accidents*, not
malevolent actors. And, even so, often not very well (\"Who\'da thought a
tsunami would flood the generators/pumps located in the basement?!\")

If the pumps must continue in perpetuity (even when \"cold\"), one has to
wonder how vulnerable *they* are to being compromised. And, with \"repair
crews\" not just a phone call away...

It\'s not reactor, it\'s reactors, this place has 6.

Yes, it\'s not uncommon to have more than one reactor at a site.
TMI had two, Chernobyl 4, Fukishima 6, etc.

But, that doesn\'t change the fact that only the containment
vessel is \"hardened\". I imagine there are lots of \"soft targets\"
(e.g., for a malevolent actor -- like a military!) to attack
that can effectively compromise the entire facility. Esp if
getting repairs isn\'t easy (due to the local conditions).

They already shut 5 of the 6 down into \"cold state\" and the sixth was kept
operational to generate enough electricity to power its own cooling system
as well as maintenance cooling for the cold state reactors. They referred to
this mode of operation as \"island mode.\" As of Saturday they restored the
Ukraine national grid power to the plant site enabling them to initiate
shutdown of the 6th reactor into the cold state, using the external grid to
power the requisite cooling loads. They say the shut down is a 30 hour
process, so it should be in cold state by now. Having all the reactors now
in the cold state has eliminated any chance for a Chernobyl type of
disaster. And the cold state maintenance cooling would be a light load for
the auxiliary power generation in the event it\'s ever needed. Underloading

Unless *it* becomes compromised.

As I said, these things were designed to tolerate *accidents*,
not deliberate hostile actors.

This is true of most infrastructure that \"society\" relies upon for
its normal functioning.

[We had a natural gas *shortage* caused by excessive demand.
As a result, appliances (furnaces, etc.) couldn\'t maintain ignition.
Nothing you could do about it -- other than disconnecting legitimate
customers from the supply (so everyone else could use the supply
that remained).]

It\'s scary to think about what *your* neighborhood relies upon
and the measures taken (or not!) to ensure it\'s continued
viability!

the generations should mean the fuel consumption is greatly reduced, one
would think, so it would be less of a crisis to keep them fully fueled. Of
course the media is greatly disappointed and scrambling to find some other
story to shock and awe the populace, which is all about viewership and
charging top dollar for advertisements.

 

[Fred Bloggs]

On Monday, September 12, 2022 at 6:30:58 AM UTC-4, Don Y wrote:

On 9/12/2022 2:38 AM, Fred Bloggs wrote:
On Monday, September 12, 2022 at 5:08:19 AM UTC-4, Don Y wrote:
On 9/12/2022 1:34 AM, Martin Brown wrote:
Once it has cooled down enough you don\'t need to be running the coolant
pumps full bore and the amount of power needed is within what emergency
backup generators can supply. ISTR most have two independent grid
connections so that cooling can be maintained even if one link fails.
That\'s how its done in the UK anyway. I don\'t think anyone considered
the possibility of having a full scale war raging round a nuclear
plant.
^^^^ this
I think the reactor containment is supposed to be good enough to
survive everything except a deliberate direct hit with the right sort of
armour piercing ordinance. We may yet find out if that really is the
case.
Much (all?) infrastructure is designed to address *accidents*, not
malevolent actors. And, even so, often not very well (\"Who\'da thought a
tsunami would flood the generators/pumps located in the basement?!\")

If the pumps must continue in perpetuity (even when \"cold\"), one has to
wonder how vulnerable *they* are to being compromised. And, with \"repair
crews\" not just a phone call away...

It\'s not reactor, it\'s reactors, this place has 6.
Yes, it\'s not uncommon to have more than one reactor at a site.
TMI had two, Chernobyl 4, Fukishima 6, etc.

But, that doesn\'t change the fact that only the containment
vessel is \"hardened\". I imagine there are lots of \"soft targets\"
(e.g., for a malevolent actor -- like a military!) to attack
that can effectively compromise the entire facility. Esp if
getting repairs isn\'t easy (due to the local conditions).
They already shut 5 of the 6 down into \"cold state\" and the sixth was kept
operational to generate enough electricity to power its own cooling system
as well as maintenance cooling for the cold state reactors. They referred to
this mode of operation as \"island mode.\" As of Saturday they restored the
Ukraine national grid power to the plant site enabling them to initiate
shutdown of the 6th reactor into the cold state, using the external grid to
power the requisite cooling loads. They say the shut down is a 30 hour
process, so it should be in cold state by now. Having all the reactors now
in the cold state has eliminated any chance for a Chernobyl type of
disaster. And the cold state maintenance cooling would be a light load for
the auxiliary power generation in the event it\'s ever needed. Underloading
Unless *it* becomes compromised.

As I said, these things were designed to tolerate *accidents*,
not deliberate hostile actors.

Russia is not deliberately attacking the containment structure- the most they\'re doing is maybe shelling switching station gear. Of course that doesn\'t preclude the existence of a Russian lunatic thinking it would be real cool to put a hole in the containment building.

This is true of most infrastructure that \"society\" relies upon for
its normal functioning.

[We had a natural gas *shortage* caused by excessive demand.
As a result, appliances (furnaces, etc.) couldn\'t maintain ignition.
Nothing you could do about it -- other than disconnecting legitimate
customers from the supply (so everyone else could use the supply
that remained).]

It\'s scary to think about what *your* neighborhood relies upon
and the measures taken (or not!) to ensure it\'s continued
viability!
the generations should mean the fuel consumption is greatly reduced, one
would think, so it would be less of a crisis to keep them fully fueled. Of
course the media is greatly disappointed and scrambling to find some other
story to shock and awe the populace, which is all about viewership and
charging top dollar for advertisements.

 

[server]

On Mon, 12 Sep 2022 09:34:20 +0100, Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

Once it has cooled down enough you don\'t need to be running the coolant
pumps full bore and the amount of power needed is within what emergency
backup generators can supply. ISTR most have two independent grid
connections so that cooling can be maintained even if one link fails.
That\'s how its done in the UK anyway. I don\'t think anyone considered
the possibility of having a full scale war raging round a nuclear plant.

At least in some countries they run dedicated direct high voltage
lines from a nearby hydroelectric plant. The hydros are considered
foolproof.

I do not know if they have hydros in Ukraine (it is quite flat), but
according to the news, they just repaired some auxiliary line to allow
removing the decay heat. Is it just a connection to the national grid
or do they have some external facility ?

 

[server]

On Thu, 15 Sep 2022 18:53:45 -0000 (UTC), antispam@math.uni.wroc.pl
wrote:

upsidedown@downunder.com wrote:
On Mon, 12 Sep 2022 09:34:20 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


Once it has cooled down enough you don\'t need to be running the coolant
pumps full bore and the amount of power needed is within what emergency
backup generators can supply. ISTR most have two independent grid
connections so that cooling can be maintained even if one link fails.
That\'s how its done in the UK anyway. I don\'t think anyone considered
the possibility of having a full scale war raging round a nuclear plant.

At least in some countries they run dedicated direct high voltage
lines from a nearby hydroelectric plant. The hydros are considered
foolproof.

If I read news report correcty Zaporizhzhia had 4 independent connections
to the grid + dedicated connection to nearby thermal power plant.
Possibly journalists exaggerated and connection to thermal plant
was counted among 4 connections. Anyway, there was a lot of redundancy.

I do not know if they have hydros in Ukraine (it is quite flat),

There are. But backup plant for Zaporizhzhia is thermal one.

Unless the thermal plant is guarantied to be running 24/365 it is
useless for nuclear plant emergency operations.

If the thermal plant is down and you have to restart it, it takes
several hours and by that time the nuclear site has already melted

but
according to the news, they just repaired some auxiliary line to allow
removing the decay heat. Is it just a connection to the national grid
or do they have some external facility ?

IIUC they repaired connection to nearby thermal power plant.

 

[a a]

On Sunday, 11 September 2022 at 14:57:04 UTC+2, Fred Bloggs wrote:
--- Chernobyl released a bunch of radioactive clouds that blanketed all of western Europe

fake
radioactive clouds never blanketed any country of western Europe
since no rise in radiation was detected by network of radiation detectors at weather station control points

 

[Martin Brown]

On 12/09/2022 14:12, upsidedown@downunder.com wrote:

On Mon, 12 Sep 2022 09:34:20 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


Once it has cooled down enough you don\'t need to be running the coolant
pumps full bore and the amount of power needed is within what emergency
backup generators can supply. ISTR most have two independent grid
connections so that cooling can be maintained even if one link fails.
That\'s how its done in the UK anyway. I don\'t think anyone considered
the possibility of having a full scale war raging round a nuclear plant.

At least in some countries they run dedicated direct high voltage
lines from a nearby hydroelectric plant. The hydros are considered
foolproof.

That assumes you have one nearby. Most UK nuclear sites do not. The only
one that might have was the experimental reactor at Dounreay home of the
worlds only radioactive caustic soda plant. Using liquid sodium as
coolant made life too interesting. Cleaning it all up is still ongoing:

https://www.neimagazine.com/features/featuresodium-success-story-at-dounreays-pfr-9408761/

I do not know if they have hydros in Ukraine (it is quite flat), but
according to the news, they just repaired some auxiliary line to allow
removing the decay heat. Is it just a connection to the national grid
or do they have some external facility ?

I think most UK nuclear sites have (at least) two independent feeds off
different subgrids so that no one line failure or grid segment collapse
(other than near total national blackout) can take both down at once.

They are more likely to have a (dedicated) gas turbine standby backup
somewhere nearby if all else fails.

--
Regards,
Martin Brown

 

[Lasse Langwadt Christensen]

fredag den 16. september 2022 kl. 14.05.29 UTC+2 skrev a a:

On Sunday, 11 September 2022 at 14:57:04 UTC+2, Fred Bloggs wrote:
--- Chernobyl released a bunch of radioactive clouds that blanketed all of western Europe

fake
radioactive clouds never blanketed any country of western Europe
since no rise in radiation was detected by network of radiation detectors at weather station control points

you don\'t consider Sweden western Europe? increased radiation was first detected at the Forsmark Nuclear Power Plant in Sweden, 12 hours before Moscow admitted there had been an accident

 

[Anthony William Sloman]

On Friday, September 16, 2022 at 10:05:29 PM UTC+10, a a wrote:

On Sunday, 11 September 2022 at 14:57:04 UTC+2, Fred Bloggs wrote:
--- Chernobyl released a bunch of radioactive clouds that blanketed all of western Europe

fake
radioactive clouds never blanketed any country of western Europe
since no rise in radiation was detected by network of radiation detectors at weather station control points

That\'s not the way I remember it.

--
Bill Sloman, Sydney

 

[Glen Walpert]

On Mon, 12 Sep 2022 15:24:24 +0100, Martin Brown wrote:

On 12/09/2022 14:12, upsidedown@downunder.com wrote:
On Mon, 12 Sep 2022 09:34:20 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


Once it has cooled down enough you don\'t need to be running the
coolant pumps full bore and the amount of power needed is within what
emergency backup generators can supply. ISTR most have two independent
grid connections so that cooling can be maintained even if one link
fails. That\'s how its done in the UK anyway. I don\'t think anyone
considered the possibility of having a full scale war raging round a
nuclear plant.

At least in some countries they run dedicated direct high voltage lines
from a nearby hydroelectric plant. The hydros are considered foolproof.

That assumes you have one nearby. Most UK nuclear sites do not. The only
one that might have was the experimental reactor at Dounreay home of the
worlds only radioactive caustic soda plant. Using liquid sodium as
coolant made life too interesting. Cleaning it all up is still ongoing:

https://www.neimagazine.com/features/featuresodium-success-story-at-
dounreays-pfr-9408761/

Sodium cooled FBR\'s now in the planning stage:
https://www.terrapower.com/our-work/natriumpower/

I did a lot of testing of shaft seals for sodium pumps for the
subsequently canceled Clinch River FBR in \'74-75 while I was a full time
lab tech at the Stein Seal Co. & part time engineering student. Safely
pumping hot pressurized radioactive sodium is now a long solved problem,
although those who solved the problem last time are either retired or dead
now.

I do not know if they have hydros in Ukraine (it is quite flat), but
according to the news, they just repaired some auxiliary line to allow
removing the decay heat. Is it just a connection to the national grid
or do they have some external facility ?

I think most UK nuclear sites have (at least) two independent feeds off
different subgrids so that no one line failure or grid segment collapse
(other than near total national blackout) can take both down at once.

They are more likely to have a (dedicated) gas turbine standby backup
somewhere nearby if all else fails.

All Nuke plants I know of in the US use on-site diesel generators for
backup power, tested monthly for ability to reach full load from a cold
start in under a minute. I have heard several reports than the problem
Ukraine reactor has had to use backup diesel power several times and thus
has an unknown but not full amount of diesel fuel remaining.

 

[Don Y]

On 9/12/2022 4:04 AM, Fred Bloggs wrote:

On Monday, September 12, 2022 at 6:30:58 AM UTC-4, Don Y wrote:
On 9/12/2022 2:38 AM, Fred Bloggs wrote:
On Monday, September 12, 2022 at 5:08:19 AM UTC-4, Don Y wrote:
On 9/12/2022 1:34 AM, Martin Brown wrote:
Once it has cooled down enough you don\'t need to be running the
coolant pumps full bore and the amount of power needed is within
what emergency backup generators can supply. ISTR most have two
independent grid connections so that cooling can be maintained even
if one link fails. That\'s how its done in the UK anyway. I don\'t
think anyone considered the possibility of having a full scale war
raging round a nuclear plant.
^^^^ this
I think the reactor containment is supposed to be good enough to
survive everything except a deliberate direct hit with the right
sort of armour piercing ordinance. We may yet find out if that
really is the case.
Much (all?) infrastructure is designed to address *accidents*, not
malevolent actors. And, even so, often not very well (\"Who\'da thought
a tsunami would flood the generators/pumps located in the
basement?!\")

If the pumps must continue in perpetuity (even when \"cold\"), one has
to wonder how vulnerable *they* are to being compromised. And, with
\"repair crews\" not just a phone call away...

It\'s not reactor, it\'s reactors, this place has 6.
Yes, it\'s not uncommon to have more than one reactor at a site. TMI had
two, Chernobyl 4, Fukishima 6, etc.

But, that doesn\'t change the fact that only the containment vessel is
\"hardened\". I imagine there are lots of \"soft targets\" (e.g., for a
malevolent actor -- like a military!) to attack that can effectively
compromise the entire facility. Esp if getting repairs isn\'t easy (due to
the local conditions).
They already shut 5 of the 6 down into \"cold state\" and the sixth was
kept operational to generate enough electricity to power its own cooling
system as well as maintenance cooling for the cold state reactors. They
referred to this mode of operation as \"island mode.\" As of Saturday they
restored the Ukraine national grid power to the plant site enabling them
to initiate shutdown of the 6th reactor into the cold state, using the
external grid to power the requisite cooling loads. They say the shut
down is a 30 hour process, so it should be in cold state by now. Having
all the reactors now in the cold state has eliminated any chance for a
Chernobyl type of disaster. And the cold state maintenance cooling would
be a light load for the auxiliary power generation in the event it\'s
ever needed. Underloading
Unless *it* becomes compromised.

As I said, these things were designed to tolerate *accidents*, not
deliberate hostile actors.

Russia is not deliberately attacking the containment structure- the most

Yet!

they\'re doing is maybe shelling switching station gear. Of course that
doesn\'t preclude the existence of a Russian lunatic thinking it would be
real cool to put a hole in the containment building.

Or, someone beating their chest in a silly display of bravado.
(Or, someone with nothing to lose after having lost it all, already!)

People have done crazy things in the past (fly planes into buildings)...

 

[Mike Monett VE3BTI]

Glen Walpert <nospam@null.void> wrote:

Sodium cooled FBR\'s now in the planning stage:
https://www.terrapower.com/our-work/natriumpower/

I did a lot of testing of shaft seals for sodium pumps for the
subsequently canceled Clinch River FBR in \'74-75 while I was a full time
lab tech at the Stein Seal Co. & part time engineering student. Safely
pumping hot pressurized radioactive sodium is now a long solved problem,
although those who solved the problem last time are either retired or
dead now.

That still leaves hot radioactive fuel rods to store forever that only
have 0.5% to 0.7% of their energy used, and some kind of fault that
produces a meltdown, such as a fire or earthquake.

The solution is Thorium Molted Salt Reactors. These operate at atmospheric
pressure and at 1250F to 1400F, temperatures that pressurized water
reactors cannot reach. This increases thermal efficiency and allows liquid
CO2 to transfer the heat to drive turbines, which can be much smaller and
fit on a tabletop.

The reactors cannot melt down since they are already molten. They a
walk-away safe, since any fault will melt a frozen drain plug and drain
the salt into a holding tank.

These reactors use virtually 100% of the energy available. There is enough
thorium to last for thousands of years.

The tiny amount of radioactive waste only remains hot for a very short
time, about 300 years compared to the millennia of pressurized water
reactors.

TMSR\'s do not have to be situated near water like PWR\'s. China is building
one in the desert.

There is a lot of information and misinformation on the web. One of the
best sources is Kirk Sorenson of Flibe Energy;

Molten-Salt Reactor Choices - Kirk Sorensen of Flibe Energy
https://www.youtube.com/watch?v=mz49CB8XGQo

A bit of encouragement:

Thorium Lifters Could Power Civilization for BILLIONS of Years!
https://www.youtube.com/watch?v=74iiaXIVtZI

China\'s Molten Salt Reactor Program and the Thorium Fuel Cycle/U233
https://www.youtube.com/watch?v=smI7NdmQ7gc




--
MRM

 

[Mike Monett VE3BTI]

Mike Monett VE3BTI <spamme@not.com> wrote:

> The solution is Thorium Molted Salt Reactors.

Typo. s/b Molten



--
MRM

 

[Lasse Langwadt Christensen]

mandag den 12. september 2022 kl. 17.16.07 UTC+2 skrev Glen Walpert:

On Mon, 12 Sep 2022 15:24:24 +0100, Martin Brown wrote:

On 12/09/2022 14:12, upsid...@downunder.com wrote:
On Mon, 12 Sep 2022 09:34:20 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


Once it has cooled down enough you don\'t need to be running the
coolant pumps full bore and the amount of power needed is within what
emergency backup generators can supply. ISTR most have two independent
grid connections so that cooling can be maintained even if one link
fails. That\'s how its done in the UK anyway. I don\'t think anyone
considered the possibility of having a full scale war raging round a
nuclear plant.

At least in some countries they run dedicated direct high voltage lines
from a nearby hydroelectric plant. The hydros are considered foolproof.

That assumes you have one nearby. Most UK nuclear sites do not. The only
one that might have was the experimental reactor at Dounreay home of the
worlds only radioactive caustic soda plant. Using liquid sodium as
coolant made life too interesting. Cleaning it all up is still ongoing:

https://www.neimagazine.com/features/featuresodium-success-story-at-
dounreays-pfr-9408761/
Sodium cooled FBR\'s now in the planning stage:
https://www.terrapower.com/our-work/natriumpower/

I did a lot of testing of shaft seals for sodium pumps for the
subsequently canceled Clinch River FBR in \'74-75 while I was a full time
lab tech at the Stein Seal Co. & part time engineering student. Safely
pumping hot pressurized radioactive sodium is now a long solved problem,
although those who solved the problem last time are either retired or dead
now.

I thought they would use electromagnetic pump so it would be a close system
with no shafts or seals

I do not know if they have hydros in Ukraine (it is quite flat), but
according to the news, they just repaired some auxiliary line to allow
removing the decay heat. Is it just a connection to the national grid
or do they have some external facility ?

I think most UK nuclear sites have (at least) two independent feeds off
different subgrids so that no one line failure or grid segment collapse
(other than near total national blackout) can take both down at once.

They are more likely to have a (dedicated) gas turbine standby backup
somewhere nearby if all else fails.
All Nuke plants I know of in the US use on-site diesel generators for
backup power, tested monthly for ability to reach full load from a cold
start in under a minute. I have heard several reports than the problem
Ukraine reactor has had to use backup diesel power several times and thus
has an unknown but not full amount of diesel fuel remaining.

they keep the coolant and oil hot 24-7 or use turbines?

piston engines don\'t like full power before they are warmed up, turbines don\'t really care

 

[John Walliker]

On Friday, 16 September 2022 at 14:51:40 UTC+1, bill....@ieee.org wrote:

On Friday, September 16, 2022 at 10:05:29 PM UTC+10, a a wrote:
On Sunday, 11 September 2022 at 14:57:04 UTC+2, Fred Bloggs wrote:
--- Chernobyl released a bunch of radioactive clouds that blanketed all of western Europe

fake
radioactive clouds never blanketed any country of western Europe
since no rise in radiation was detected by network of radiation detectors at weather station control points
That\'s not the way I remember it.

Nor me. There was fallout in the UK afterwards. Areas with high rainfall were
affected most as Caesium 137 was washed out of the atmosphere. This meant that
sheep in some parts of Wales have been monitored ever since. Fortunately,
the Caesium has now mostly decayed (the half life is about 30 years) or been
washed out of the ground.
There was also contamination in London. A friend who was a radiation
protection physicist measured the activity of the filters in the main air conditioning
system at a large hospital and found that the filters would need to be handled
as medium level radioactive waste. Most of the activity in the filters was
from iodine 131 which had been adsorbed onto fine airborne soil particles.
Iodine 131 decays very quickly as the half-life is only about 8 days.

John

 

[Fred Bloggs]

On Monday, September 12, 2022 at 2:20:25 PM UTC-4, lang...@fonz.dk wrote:

mandag den 12. september 2022 kl. 17.16.07 UTC+2 skrev Glen Walpert:
On Mon, 12 Sep 2022 15:24:24 +0100, Martin Brown wrote:

On 12/09/2022 14:12, upsid...@downunder.com wrote:
On Mon, 12 Sep 2022 09:34:20 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


Once it has cooled down enough you don\'t need to be running the
coolant pumps full bore and the amount of power needed is within what
emergency backup generators can supply. ISTR most have two independent
grid connections so that cooling can be maintained even if one link
fails. That\'s how its done in the UK anyway. I don\'t think anyone
considered the possibility of having a full scale war raging round a
nuclear plant.

At least in some countries they run dedicated direct high voltage lines
from a nearby hydroelectric plant. The hydros are considered foolproof.

That assumes you have one nearby. Most UK nuclear sites do not. The only
one that might have was the experimental reactor at Dounreay home of the
worlds only radioactive caustic soda plant. Using liquid sodium as
coolant made life too interesting. Cleaning it all up is still ongoing:

https://www.neimagazine.com/features/featuresodium-success-story-at-
dounreays-pfr-9408761/
Sodium cooled FBR\'s now in the planning stage:
https://www.terrapower.com/our-work/natriumpower/

I did a lot of testing of shaft seals for sodium pumps for the
subsequently canceled Clinch River FBR in \'74-75 while I was a full time
lab tech at the Stein Seal Co. & part time engineering student. Safely
pumping hot pressurized radioactive sodium is now a long solved problem,
although those who solved the problem last time are either retired or dead
now.
I thought they would use electromagnetic pump so it would be a close system
with no shafts or seals
I do not know if they have hydros in Ukraine (it is quite flat), but
according to the news, they just repaired some auxiliary line to allow
removing the decay heat. Is it just a connection to the national grid
or do they have some external facility ?

I think most UK nuclear sites have (at least) two independent feeds off
different subgrids so that no one line failure or grid segment collapse
(other than near total national blackout) can take both down at once.

They are more likely to have a (dedicated) gas turbine standby backup
somewhere nearby if all else fails.
All Nuke plants I know of in the US use on-site diesel generators for
backup power, tested monthly for ability to reach full load from a cold
start in under a minute. I have heard several reports than the problem
Ukraine reactor has had to use backup diesel power several times and thus
has an unknown but not full amount of diesel fuel remaining.
they keep the coolant and oil hot 24-7 or use turbines?

piston engines don\'t like full power before they are warmed up, turbines don\'t really care

They use engine block heaters:
\"the National Fire Protection Agency (NFPA) requires that standby generators be heated as necessary to ensure the system will start and carry the full emergency loads within ten seconds after loss of primary power from the utility service.\"
The block heaters should be thermostatically controlled to keep the block above 60oF is all that\'s needed most of the time. It doesn\'t need to be \"hot.\"

 

[Jeroen Belleman]

On 2022-09-12 15:12, upsidedown@downunder.com wrote:

On Mon, 12 Sep 2022 09:34:20 +0100, Martin Brown
\'\'\'newspam\'\'\'@nonad.co.uk> wrote:


Once it has cooled down enough you don\'t need to be running the coolant
pumps full bore and the amount of power needed is within what emergency
backup generators can supply. ISTR most have two independent grid
connections so that cooling can be maintained even if one link fails.
That\'s how its done in the UK anyway. I don\'t think anyone considered
the possibility of having a full scale war raging round a nuclear plant.

At least in some countries they run dedicated direct high voltage
lines from a nearby hydroelectric plant. The hydros are considered
foolproof.

I do not know if they have hydros in Ukraine (it is quite flat), but
according to the news, they just repaired some auxiliary line to allow
removing the decay heat. Is it just a connection to the national grid
or do they have some external facility ?

If they have 200MWth available even with the reactor shut down, why
did no one think of using that to drive a few smaller auxiliary
turbines with that? What madness brought them to designing a plant
that cannot be shut down and kept in a safe state on its own?

Jeroen Belleman