Turkey Point nuclear powerplant and Irma?

[PFreader]

Hi
Sorry, English is not my first language.

Is Turkey Point nuclear powerplant in Florida safe for the storm surge of Irma ?

 

[FactChecker]

Good question. I just saw on the news that those power plants are being shut down before the hurricane hits. The plant elevation is only 3 feet above sea level, but there are levees around it. I don't know the height of the levees.

 

[jim hardy]

It's not levees - the the whole site is filled to 18 feet elevation.

It''s the highest ground for miles, plenty of room for water from Biscayne Bay to run around it.

 

[jim hardy]

From @PFreader 's link
my arrow is at Turkey Point

 

[PFreader]

Ok, thanks

some Little room for waves.

 

[jim hardy]

some Little room for waves.

yes you don't need much. . shallow Biscayne Bay, barrier islands and a few miles of reef between plant and deep water

 

[Hiddencamper]

As of right now, Turkey Point isn't going to see hurricane force winds.

They have a requirement to bring both units to cold shutdown at least 2 hours prior to the onset of hurricane force winds.

As part of their FLEX program this allows them to survive for 24 hours without offsite assistance, utilizing portable on site pumps and if necessary, allowing the unit to heat up to mode 4 in natural circulation for the use of the turbine driven auxiliary feedwater pumps.

Within 24 hours, the two SAFER facilities in the US can airlift emergency core cooling equipment and install it.

So the risk is very low. We all need to remember that Turkey Point did get a direct hit from hurricane Andrew.

 

[jim hardy]

We all need to remember that Turkey Point did get a direct hit from hurricane Andrew.

We were without offsite power for a week. Diesels ran fine.

The plant is made of steel and concrete so wasn't bothered much at all..
Cars in parking lot got windows blown out by flying gravel from roofs, some flipped over.
Admin building maintenance shop and security fence got severe wind damage. The water tower (it used to be on East side of plant) blew down , had to repair some plumbing out there.

This one won't compare. With wind out of the South it should actually drop the water level in that end of Biscayne Bay, blowing it up North toward Miami..

old jim

 

[jim hardy]

With wind out of the South it should actually drop the water level in that end of Biscayne Bay, blowing it up North toward Miami..

Hoping Mother Nature doesn't surprise us -

old jim

 

[HowlerMonkey]

Nothing to worry about at turkey point with the current track but I wonder about the spent fuel at crystal river npp but not sure of cooling requirements.

 

[jim hardy]

Nothing to worry about at turkey point with the current track

I was never at Crystal River - went past it once in a boat is all.

Maybe we have a PF'er from there ?

 

[Hiddencamper]

Nothing to worry about at turkey point with the current track but I wonder about the spent fuel at crystal river npp but not sure of cooling requirements.

The spent fuel pool doesn't matter any more. That stuff is air coolable now. It's been several years and has decayed sufficiently. It might all be in dry cask storage making the whole issue moot.

 

[FactChecker]

They have a requirement to bring both units to cold shutdown at least 2 hours prior to the onset of hurricane force winds.

As part of their FLEX program this allows them to survive for 24 hours without offsite assistance, utilizing portable on site pumps and if necessary, allowing the unit to heat up to mode 4 in natural circulation for the use of the turbine driven auxiliary feedwater pumps.

Within 24 hours, the two SAFER facilities in the US can airlift emergency core cooling equipment and install it.

Is emergency core cooling equipment needed after a cold shutdown, or is that for other situations?

 

[jim hardy]

Is emergency core cooling equipment needed after a cold shutdown, or is that for other situations?

Not dodging your question -
Some of the equipment does double duty . So that equipment is needed but it's not doing emergency cooling .
Example - seawater pumps that provide cooling water to heat exchangers for both emergency and non emergency cooling are of course needed.
"Low Head Safety Injection " function (LHSI) uses same pumps as "Residual Heat Removal" function (RHR) - when you get to cold shutdown you re-align their valves to circulate reactor coolant through heat exchangers for long term core cooling.

So i'd say the complete answer is a qualified yes,
we need pumps and heat exchangers and valves and instruments. Some of it is the same equipment we'd use in an emergency.

old jim

 

[Hiddencamper]

If they had damage to equipment and lost cooling systems the reactor would heat back up again. That's why you count on getting ECCS equipment delivered.

 

[mheslep]

If they had damage to equipment and lost cooling systems the reactor would heat back up again. That's why you count on getting ECCS equipment delivered.

The heat back up time from cold shut down must be far longer than the point from which Fukushima reactors started elevating temperature, 41 minutes after shutdown.

 

[FactChecker]

The heat back up time from cold shut down must be far longer than the point from which Fukushima reactors started elevating temperature, 41 minutes after shutdown.

That's not an encouraging comparison.

 

[mheslep]

That's not an encouraging comparison.

Perhaps due to my sloppy phrasing. There's a point in time after a shutdown where there's no longer enough decay heat to destroy the reactor without active cooling, certainly not enough to melt the vessel. I don't know when that time occurs, though after a cold shut down that path to walk-away-safe is underway. Also, should some catastrophic external event occur that knocks out cooling after a cold shut down, a lot of time remains to remedy the situation (a week?).

By contrast, Fukushima had no such lengthy grace period (quake forced shutdown, and loss of active cooling 41 min later).

Encouraging?

 

[FactChecker]

a lot of time remains to remedy the situation (a week?).
Encouraging?

Yes. Thanks.

 

[Hiddencamper]

After getting into cold shutdown it's not uncommon to have a 40-60 degF per hour heatup rate. When I shut my BWR down for refuel we were at 65 degF per hour heatup rate initially on just decay heat. So realistically, being in cold shutdown buys you several hours to do something assuming the vessel is sealed and all safety systems are available.

I know at my plant when we are cold we have our head vent open, so if we lost all power we would have to figure out how to get the vent shut otherwise we would direct boil to the containment atmosphere.

The time until the reactor is walk away safe is months or more. The only passive heat removal from the reactor is thermal radiative, which for a General Electric BWR is assumed to be 1.1MW. So it would take probably over a year technically to be walk away safe.

However cold shutdown buys a tremendous amount of time.

For a hot reactor, a BWR gets around 1 hour and a PWR gets around 2 hours before fuel overheat begins. At Fukushima those units were essentially at rated pressure and temperature so there was no heatup time. Decay heat directly boiled off reactor coolant.

There are a number of reasons you go to cold shutdown. Being cold means little or no pressure, so leaks are minimized. Being cold also means anything can inject to the reactor, including low pressure eccs. This can be good or bad, but at least they are available if needed. Cold shutdown generally improves plant risk, but there are risks getting there as mode 3 operation is a higher risk mode.

 

[jim hardy]

Being cold also means anything can inject to the reactor, including low pressure eccs.

And if you were in a real jam & needing to do that, since the pipes aren't scalding hot you could get to one to hook something up .

old jim