Russian Nuclear Plant

[watchforwater]

I thought it was interesting,

http://englishrussia.com/?p=2660

[watchforwater]

Someone please explain whats up with the loading of the reactor fuel from that Russian plant.

[RDTroja]

I like the part where they say the fuel is Uranium 255.

Maybe they know something we don't?

[roadhp]

The open toe shoes of the worker was interesting.  My question is was that the reactor or the spent fuel pool, since you could see the glow?  Obviously the spent fuel pool, since there wasn't the mass confusion associated with a refuel, and no reactor head stand, etc.

[RDTroja]

The open toe shoes of the worker was interesting.  My question is was that the reactor or the spent fuel pool, since you could see the glow?  Obviously the spent fuel pool, since there wasn't the mass confusion associated with a refuel, and no reactor head stand, etc.

Or, perhaps it is an open pool type reactor. Even though I have only seen low power reactors with an open pool, maybe the Russians have yet another unusual design for their power reactors. Look what a success the RBMK design turned out to be.

[Adam Grundleger]

I think it's an RBMK 1000.  They refuel at-power with the robotic mechanism in the picture.  There is no single vessel head, as each element is in a separate vessel with an individual closure head.  The vessels are joined by piping to share a common coolant and are graphite moderated.  

I don't think the cavity between the vessels is flooded.  Does that mean the Cerenkov radiation is in air?  

BTW, notice the fuel assemblies hanging from overhead racks with no positive control.

The more of this I see, the more I wonder how these units got the reputation for safety and reliability they had before Chernobyl 4.  That they kept building these after 1986 is hard to believe.  

[watchforwater]

I dont think that was the spent fuel pool. It could be I guess, it said it was only 8ft deep.  Also it looked like everything hangs from racks. thats nuts no wonder those people blew themselves up.... more than once.....k19

Matthew

[Adam Grundleger]

www.nucleartourist.com has a cutaway diagram of the RBMK and it looks like that's the top of the reactor, not the pool.  I don't know for sure if they even have a spent fuel pool.  Anybody?

Plus, assuming that I'm right and the Cerenkov radiation is visible in air at 8 ft into the cavity (above the upper bio-shield,) then what insanely high dose rate would be required to see a visible glow in air? 

[watchforwater]

I had a senior RP tell me one time back in the days they dropped a film down into the reactor during refueling to read the amount as we no instruments will. It was then sent it off for testing and it had been exposed to 125,000 REM!!!

Matthew

[RDTroja]

I had a senior RP tell me one time back in the days they dropped a film down into the reactor during refueling to read the amount as we no instruments will. It was then sent it off for testing and it had been exposed to 125,000 REM!!!

Matthew

How long did they leave it in there? 125,000 REM is not a lot for spent fuel. I personally took a reading on a spent fuel bundle fresh out of the reactor and got ~400,000 REM/hr at about a foot away. That was with an RO-7... I can't personally vouch for the calibration of the instrument at that range, but it seems to be about right based on other estimates I have heard.

[watchforwater]

The way I understood it, it was lowered down then instantly brought back up. Wow 400,000 huh thats crazy. I guess it is true that would kill someone instantly.

[Marlin]

Why?

Just curiosity I would assume, I have done the same, but that was in the late 70s. I haven't seen a meter with that kind of range for a long time, not really much need for one.

[Adam Grundleger]

Did some digging:  The pictures are from Smolensk number 3.  That picture is definitely the top of the reactor.  The more I read up on the RBMKs the more hideous they seem. 

BTW, there's a youtube video of a refueling that purports to be from an RBMK, but it's definitely a US PWR.  It actually looks way too familiar.  That stuff really doesn't need to be on youtube.

[Chimera]

How long did they leave it in there? 125,000 REM is not a lot for spent fuel. I personally took a reading on a spent fuel bundle fresh out of the reactor and got ~400,000 REM/hr at about a foot away. That was with an RO-7... I can't personally vouch for the calibration of the instrument at that range, but it seems to be about right based on other estimates I have heard.

While it's probably not something I should admit to, you're numbers agree with what we measured at Millstone I back in the late '70's.  As an aside, doesn't the high range detector on the RO-7 over-range at 200K?  I know that's off-topic, but . . . curiousity is an overwhelming thing.

[Marlin]

While it's probably not something I should admit to, you're numbers agree with what we measured at Millstone I back in the late '70's.  As an aside, doesn't the high range detector on the RO-7 over-range at 200K?  I know that's off-topic, but . . . curiousity is an overwhelming thing.

   The meter I used pegged on the side of the up-ender and dropped onto range (1million Rad) just barely off of it. Later I learned from a GE engineer that 1 to 2 million contact is a good ball park number for contact dose rate of a fresh bundle. I have seen decay graphs of fuel bundles, they decay pretty quickly from the very high dose rates (curies on the graphs) to the still prohibitive lower ones of the bundles sent to dry cells. I haven't done any  dry cell fuel storage work but I'm sure some one on this site has and can illuminate us and I'm sure they were curious also  .
   The RO 7 must have new detectors and electronics I remember 20K as it's over range, but then I have not had one in my hands for about 20 years.

[UncaBuffalo]

   The meter I used pegged on the side of the up-ender and dropped onto range (1million Rad) just barely off of it. Later I learned from a GE engineer that 1 to 2 million contact is a good ball park number for contact dose rate of a fresh bundle. I have seen decay graphs of fuel bundles, they decay pretty quickly from the very high dose rates (curies on the graphs) to the still prohibitive lower ones of the bundles sent to dry cells. I haven't done any  dry cell fuel storage work but I'm sure some one on this site has and can illuminate us and I'm sure they were curious also  .
   The RO 7 must have new detectors and electronics I remember 20K as it's over range, but then I have not had one in my hands for about 20 years.

You remember correctly... 

http://www.thermo.com/com/cda/product/detail/1,,10123133,00.html

[matthew.b]

I don't think the cavity between the vessels is flooded.  Does that mean the Cerenkov radiation is in air?

Yep. 

All of those squares are removable caps over the core.  Each one covers a separate fuel channel.

The refuel machine pulls one of the caps and then they can open that fuel channel and change the fuel rod at full power.  One part of the machine removes the cap and then it moves over.  Between procedures the top of the core is exposed at full power out several of the cap holes.  Walking over the gap would be instant death.  The top of the upper core room has a several foot thick concrete bioshield to stop the shine from going through the plant roof.

[RDTroja]

While it's probably not something I should admit to, you're numbers agree with what we measured at Millstone I back in the late '70's.  As an aside, doesn't the high range detector on the RO-7 over-range at 200K?  I know that's off-topic, but . . . curiousity is an overwhelming thing.

   The meter I used pegged on the side of the up-ender and dropped onto range (1million Rad) just barely off of it. Later I learned from a GE engineer that 1 to 2 million contact is a good ball park number for contact dose rate of a fresh bundle. I have seen decay graphs of fuel bundles, they decay pretty quickly from the very high dose rates (curies on the graphs) to the still prohibitive lower ones of the bundles sent to dry cells. I haven't done any  dry cell fuel storage work but I'm sure some one on this site has and can illuminate us and I'm sure they were curious also  .

You remember correctly... 

http://www.thermo.com/com/cda/product/detail/1,,10123133,00.html

The meter I used had interchangeable probes and the highest range was up to 1,000,000 R/Hr. I would have sworn it was an RO-7 but that was in 1980, so maybe I am wrong about the instrument... or maybe the probe was discontinued, but top range was 1e⁶. After all, who can or would want to calibrate that probe?

Like Marlin, I have heard for decades that a 'fresh' end-of-life bundle was between 1e⁶ and 2e⁶ R/Hr. The theory is that if you put one on the 50 yard line and ran toward it from the end zone (assuming you were shielded there) you would drop dead at the 30. Or, if you rode past on a motorcycle at 60 mph you would be dead before you got to the other end zone.

As for the 'Why' part, I will misquote Bobby Kennedy: "Some people look at radiological challenges and ask 'Why?' I look at them and ask 'Why not?'" (Or at least, I used to.)