A trip to Chernobyl

[KokomoBusa]

No argument, just discussing stuff...

The commercial side, the fuel assembles are much larger than those used by the Navy. Enriched U-235 is used, one fuel assemble is around 12-14' long, which consists of fuel pins, which actually hold the fuel pellets, a fuel assembly may have around 100 pins. Depending on the design, the plant may have up to 500 or more fuel assemblies. Usually, 1/3 of the assemblies are replaced during the refueling outage. The fuel is designed to run between 18 or 24 months, again depends on design and operating liscense.

These numbers will vary depending on the design of the unit. Just giving a little idea on what you are looking at...

yeah, that's much larger than I would have guessed. and from the sounds of it, the fuel isn't even allowed to get near it's critical mass. Could definately see how that waste could be an issue. Thanks for info

 

[Powers739]

I guess I should have said that the fuel is good for three runs, each run is between 18 and 24 months. Each refueling outage about 1/3 of the fuel is replaces. So a fuel bundle useful life is around 4.5 to 6 years...

 

[KokomoBusa]

I guess I should have said that the fuel is good for three runs, each run is between 18 and 24 months. Each refueling outage about 1/3 of the fuel is replaces. So a fuel bundle useful life is around 4.5 to 6 years...

I think that's still pretty far from crit mass. near the end of a run, are the rods near full retraction or do they still have a bit of room to go?

 

[Powers739]

I think that's still pretty far from crit mass. near the end of a run, are the rods near full retraction or do they still have a bit of room to go?

On a PWR, the control rods are always fully out and the amount of boron in the RCS is what controls the power level, sure they will trim the control rods in a little to push the ASI down towards the bottom of the core since the top region in a little more reactive than the bottom. But towards the end of the cycle the concentrate on boron is pretty much non-existant. The fuel and fuel loading is designed to be fully depleated at the end of the run (18 or 24 month, whatever is designed and licensed for).

On a BWR, no boron is used for a moderator, so the rods are trimmed in and out as necessary and the recirculation flow to control power.

The plants are designed to run with the rods out. Again, the fuel is designed to burn out after their run, so towards the end of the cycle, the plant may not be able to produce 100% and it will coast down until the planned refueling outage...

 

[KokomoBusa]

On a PWR, the control rods are always fully out and the amount of boron in the RCS is what controls the power level, sure they will trim the control rods in a little to push the ASI down towards the bottom of the core since the top region in a little more reactive than the bottom. But towards the end of the cycle the concentrate on boron is pretty much non-existant. The fuel and fuel loading is designed to be fully depleated at the end of the run (18 or 24 month, whatever is designed and licensed for).

On a BWR, no boron is used for a moderator, so the rods are trimmed in and out as necessary and the recirculation flow to control power.

The plants are designed to run with the rods out. Again, the fuel is designed to burn out after their run, so towards the end of the cycle, the plant may not be able to produce 100% and it will coast down until the planned refueling outage...

super cool, thanks for the schooling heh

 

[Powers739]

No problem

 

[euroR]

As I am going through those photos all I am thinking is I have been there. CALL OF DUTY 4, they really got the location right from the hotel to playground.

 

[RedBull]

Yep . . .

All I can say is that
about every 6 months
we review incidents like
this as a reminder . . .