the lines to the turbine and back are sealed. when there is a full loss of offsite power, the reactor protection system relays and isolation system relays and solonoids lose their charge. the moment that happens the reactor auto-shuts down and isolates. there are 2 sets of isolation valves, one inside the containment, and outside the containment and in the reactor building as a backup.
In other words, the containment is almost completely sealed from the outside world. One major issue is the torus isnt as well protected as the containment drywell and wetwell. it sits outside the drywell containment and in this pseudo containment that isnt sealed as well. if that's leaking that could be the source.
cant get up there. the SFP if they have less than 15 feet of water in them are deathly radioactive.
normally they measure temperature for the reactor water at the reactor water cleanup system piping, and the steam lines out. because the water levels arent up there it is hard to truely discern what the temperature is.
as for not knowing a lot, they probably still dont have their plant process computers online otherwise they'd know most of that stuff. and because of the complexity of the electrical systems they probably dont have most of their power sources up which would give them indications.
-iaane that manages a plant process computer.
iaea says for emergency and life saving, it is ok to get 500 mSv.
in the US, the moment an emergency happens everyone at the plant is authorized 50mSv instantly. If you are trying to operate or work in the plant, 100 mSv. to save life or prevent disaster 250 mSv.
These numbers have been that way for years. they aren't just authorizing more and more dose, you can find those numbers in existing plant procedures.
I know people who dive into reactor vessels.
obviously not while they are online. that's crazy sauce.
under operating conditions in a BWR, the water is about 550 F and 1000 PSI. in a PWR maybe 620 and 2000 psi. (I work at a BWR...dont know PWRs as well).
us nuclear engineers have been waiting for info like "what is power, pressure, and level at" "what is pressure suppression pressure at" "what is containment pressure at" "what is the status of all ECCS systems"
instead we hear what they are doing at the time kind of vaguely and what they think they will be doing sometimes.
i think translation barriers get in the way a little bit as well.
US plants have an emergency response data system (ERDS) which sends about 80 critical plant data parameters to NRC and other state and local agencies so these agencies can look at the data and get an idea what is going on if they need to, as well as provide support for the plant and have a better understanding of what is going on/consequences. I don't know if japan doesn't have this system, but i think they should.
i know what he was saying, but what i am saying is the earthquake was not the problem.
and its only in the last couple years that reactor designs with passive gravity driven cooling systems have even gotten certifications for design. this is due to the regulatory process. if we didnt stop building plants, and the process wasnt as cumbersome, many plants would have passive gravity driven cooling systems which can run for up to 72 hours unattended after this exact accident scenario.
the earthquake wasnt the problem. it was the tsunami. it caused damage which brought the emergency diesel generators offline.
these plants at fukushimi were offline for most of 2008 and 2009 for earthquake upgrades and it looks like they worked for the most part.
right now any damage is because they had no power and were relying on RCIC and other passive cooling systems, and even now have limited electrical power and probably limited heat sink capability.
IAANE
IAANE
Nuclear power plants are still installing equipment based on the 80386 architecture.
It is very reliable which is a requirement when working on safety systems.
The plant I work at uses about 15,000 gallons per minute.
When I say "Use" i mean, that is what we draw in from the river to replace what actually evaporates. We have a large pool of water that is many times larger than that which runs through the core multiple times.
My plant has steam towers, if we had just pumped water directly in/out from the river we would 'evaporate' less, but still use a lot of water.
A commercial reactor fuel bundle starts off with about 5% enrichment, (actually its like 4.95%).
By the time a fuel bundle is removed, it is down to about.4 to.7% uranium, and another.4-.7% plutonium (breeding), on average there's an enrichment level of just under 1% in the fuel when it is removed.
This means we use up anywhere between 5 and 8% of the fuel, at best.
I work at a nuclear plant, and the "at cost" of selling our power is between 3.5 and 5.5 cents per kwh on average over a year based on whether or not we are shut down for refueling that year.
This is at-cost, not for profit.
nuclear would only cost 16 cents per kwh if the plant was awfully mismanaged with terrible performance.
The ocean is the lowest. In a submarine. The nuclear subs have the lowest exposure rates of any core in the industry because there's also virtually no background radiation.
It's likely the leak is related to the CSTs. CSTs provide makeup water for potentially contaminated close cooling loops and a few other things that could be potentially contaminated.
About the 120% power thing, they are a 600MWe reactor. The design margins on those things are so huge because of when they were designed that they could definitely uprate another 20%. Most plants in the industry have already uprated, but those 600 MWe cores cost a lot more to uprate that it doesnt surprise me they havent yet.
The monticello nuclear plant did the 120% uprate (or is in the process of doing it now) and they've had no problems. They are just as old as VY if not older.
I do agree that entergy needs to be scrutinized a little more.
Actually oxygen tends to transmute into nitrogen-14. This happens in the reactor core. N-14 only lasts for ~7.5 seconds, but it causes the majority of radiation exposure when a BWR is online. (PWRs dont have as much of a problem because the turbine deck is made of clean water).
Reactor grade water is not corrosive at all, in fact it is extremely pure. Now there is radiation in it, but there's nothing that would necessarily cause pipe embrittlement. Pipes naturally have breaks and leaks over time, and pipes at a power plant are designed to leak before break to prevent an accident from happening. As of right now the titrated water hasnt contaminated drinking water supplies. they are test wells that all plants have to check for this kind of thing. Now if they said they found tritium in the nearby lakes and rivers i would be concerned (this coming from someone who lives next to the hanford site). Also, the radioactive waste water at hanford, they are worried it could reach the aquafer underneath it within the next 15-20 years. plenty of time to clean it up. The contamination that would get in the river wouldnt be as bad as the stuff they were spilling in there 40-50 years ago.
BWRs are only 1 stage for cooling. The water in the reactor is the water that passes through the condenser.
PWRs use 2 loops.
Vermont is a BWR. Tritium levels could be higher in there because of the massive amount of free neutrons flying around in the reactor. double neutron absorption in the water could cause it.
Shutting it down just makes it harder to find the leak, since they wont be producing radioisotopes to use, and they will be using less water, therefore they will be leaking much less.
They should keep running. Right now its not putting anyone in danger.
The corrective action process which nuclear plants use to self-police isnt exactly the fastest thing unless they think there's a health/safety issue.
If they detected tritium in water which was used for drinking it would have been escalated. I'm sure it is now.
Actually they did act. They noticed the rates increasing. They added more wells and kept testing to locate the problem. They are self-policing and reporting using their corrective action process. Going over a limit will get them a hefty fine, but all things considered when a problem just pops up like this you dont know where its at and you have little control over it. They are doing the right things.
They are finding water near the condensate storage tanks. This is water that is supposed to be used for emergency cooling, replenishing reactor feedwater, and overflow for a couple systems. It is potentially contaminated. It draws its water from the potable water system (typically in most plants), which means that the water going in is supposed to be clean. They need to check if they have a leak in there causing potentially contaminated water to go into the site's potable water system. I'm sure that was already done, at my plant it would have been done already at least.
Anyways, condensate storage tanks arent always located inside the plant. It is very likely thats where the leak is. I'm not completely sure why they are getting tritium of all things as in a BWR plant tritium usually isnt your biggest worry. Nuclear plants have a corrective action process that a plant uses to fix problems. Anyone at the plant can put something in the process, it is federally mandated, and its one of those things that an employee cannot lose his job over. The system is very effective and allows the plants to 'self-police'. Finding and fixing a problem like this when the tritium leak was low would have been a low priority fix because the tritium levels were under limits previously. One of the actions they took was likely to install the new wells to find if the leaks were worse near potentially contaminated systems, which they did and found out it was worse. Now they are likely elevating the issue internally, which is why it was reported again to the NRC.
So far, the plant sounds like they legally/procedureally done everything right. They made a huge boo-boo by having a PR guy tell people they have no underground piping that could carry contaminated water, it makes me think that guy never took or paid attention during the BWR systems class. The plant cannot be expected to prevent all accidents, but they are expected to mitigate accidents and issues to a minimal risk of safety to the public and to monitor and fix equipment which has repeat failures (things they know are breaking).
Long story short,
They are going to get investigated, and if this problem has been here longer than they say it has, they are in a bit of trouble. I
Tritium isnt terrible in the water, as long as it doesnt get into drinking water. It's in low amounts that it will be diluted easily if it reaches a main water supply. It's still not good, but there are MANY worse things that could have leaked.
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the lines to the turbine and back are sealed. when there is a full loss of offsite power, the reactor protection system relays and isolation system relays and solonoids lose their charge. the moment that happens the reactor auto-shuts down and isolates. there are 2 sets of isolation valves, one inside the containment, and outside the containment and in the reactor building as a backup. In other words, the containment is almost completely sealed from the outside world. One major issue is the torus isnt as well protected as the containment drywell and wetwell. it sits outside the drywell containment and in this pseudo containment that isnt sealed as well. if that's leaking that could be the source.
cant get up there. the SFP if they have less than 15 feet of water in them are deathly radioactive. normally they measure temperature for the reactor water at the reactor water cleanup system piping, and the steam lines out. because the water levels arent up there it is hard to truely discern what the temperature is. as for not knowing a lot, they probably still dont have their plant process computers online otherwise they'd know most of that stuff. and because of the complexity of the electrical systems they probably dont have most of their power sources up which would give them indications. -iaane that manages a plant process computer.
the core damage probability is per year. not per hour. plants in the US are not allowed to operate with more than 1 CDF per 10000 years.
iaea says for emergency and life saving, it is ok to get 500 mSv. in the US, the moment an emergency happens everyone at the plant is authorized 50mSv instantly. If you are trying to operate or work in the plant, 100 mSv. to save life or prevent disaster 250 mSv. These numbers have been that way for years. they aren't just authorizing more and more dose, you can find those numbers in existing plant procedures.
I know people who dive into reactor vessels. obviously not while they are online. that's crazy sauce. under operating conditions in a BWR, the water is about 550 F and 1000 PSI. in a PWR maybe 620 and 2000 psi. (I work at a BWR...dont know PWRs as well).
us nuclear engineers have been waiting for info like "what is power, pressure, and level at" "what is pressure suppression pressure at" "what is containment pressure at" "what is the status of all ECCS systems" instead we hear what they are doing at the time kind of vaguely and what they think they will be doing sometimes. i think translation barriers get in the way a little bit as well. US plants have an emergency response data system (ERDS) which sends about 80 critical plant data parameters to NRC and other state and local agencies so these agencies can look at the data and get an idea what is going on if they need to, as well as provide support for the plant and have a better understanding of what is going on/consequences. I don't know if japan doesn't have this system, but i think they should.
i know what he was saying, but what i am saying is the earthquake was not the problem. and its only in the last couple years that reactor designs with passive gravity driven cooling systems have even gotten certifications for design. this is due to the regulatory process. if we didnt stop building plants, and the process wasnt as cumbersome, many plants would have passive gravity driven cooling systems which can run for up to 72 hours unattended after this exact accident scenario.
the earthquake wasnt the problem. it was the tsunami. it caused damage which brought the emergency diesel generators offline. these plants at fukushimi were offline for most of 2008 and 2009 for earthquake upgrades and it looks like they worked for the most part. right now any damage is because they had no power and were relying on RCIC and other passive cooling systems, and even now have limited electrical power and probably limited heat sink capability. IAANE
IAANE Nuclear power plants are still installing equipment based on the 80386 architecture. It is very reliable which is a requirement when working on safety systems.
The plant I work at uses about 15,000 gallons per minute. When I say "Use" i mean, that is what we draw in from the river to replace what actually evaporates. We have a large pool of water that is many times larger than that which runs through the core multiple times. My plant has steam towers, if we had just pumped water directly in/out from the river we would 'evaporate' less, but still use a lot of water.
A commercial reactor fuel bundle starts off with about 5% enrichment, (actually its like 4.95%). By the time a fuel bundle is removed, it is down to about .4 to .7% uranium, and another .4-.7% plutonium (breeding), on average there's an enrichment level of just under 1% in the fuel when it is removed.
This means we use up anywhere between 5 and 8% of the fuel, at best.
I work at a nuclear plant, and the "at cost" of selling our power is between 3.5 and 5.5 cents per kwh on average over a year based on whether or not we are shut down for refueling that year. This is at-cost, not for profit. nuclear would only cost 16 cents per kwh if the plant was awfully mismanaged with terrible performance.
The ocean is the lowest. In a submarine. The nuclear subs have the lowest exposure rates of any core in the industry because there's also virtually no background radiation.
It's likely the leak is related to the CSTs. CSTs provide makeup water for potentially contaminated close cooling loops and a few other things that could be potentially contaminated.
About the 120% power thing, they are a 600MWe reactor. The design margins on those things are so huge because of when they were designed that they could definitely uprate another 20%. Most plants in the industry have already uprated, but those 600 MWe cores cost a lot more to uprate that it doesnt surprise me they havent yet. The monticello nuclear plant did the 120% uprate (or is in the process of doing it now) and they've had no problems. They are just as old as VY if not older. I do agree that entergy needs to be scrutinized a little more.
Actually oxygen tends to transmute into nitrogen-14. This happens in the reactor core. N-14 only lasts for ~7.5 seconds, but it causes the majority of radiation exposure when a BWR is online. (PWRs dont have as much of a problem because the turbine deck is made of clean water).
Reactor grade water is not corrosive at all, in fact it is extremely pure. Now there is radiation in it, but there's nothing that would necessarily cause pipe embrittlement. Pipes naturally have breaks and leaks over time, and pipes at a power plant are designed to leak before break to prevent an accident from happening. As of right now the titrated water hasnt contaminated drinking water supplies. they are test wells that all plants have to check for this kind of thing. Now if they said they found tritium in the nearby lakes and rivers i would be concerned (this coming from someone who lives next to the hanford site). Also, the radioactive waste water at hanford, they are worried it could reach the aquafer underneath it within the next 15-20 years. plenty of time to clean it up. The contamination that would get in the river wouldnt be as bad as the stuff they were spilling in there 40-50 years ago.
BWRs are only 1 stage for cooling. The water in the reactor is the water that passes through the condenser. PWRs use 2 loops. Vermont is a BWR. Tritium levels could be higher in there because of the massive amount of free neutrons flying around in the reactor. double neutron absorption in the water could cause it.
I hope they aren't dropping...Vermont is a BWR, they go up from the bottom.
Shutting it down just makes it harder to find the leak, since they wont be producing radioisotopes to use, and they will be using less water, therefore they will be leaking much less. They should keep running. Right now its not putting anyone in danger.
The corrective action process which nuclear plants use to self-police isnt exactly the fastest thing unless they think there's a health/safety issue. If they detected tritium in water which was used for drinking it would have been escalated. I'm sure it is now.
Co-60 is millions of times more dangerous than tritium. I got a feeling there's gonna be some jailing going on.
Actually they did act. They noticed the rates increasing. They added more wells and kept testing to locate the problem. They are self-policing and reporting using their corrective action process. Going over a limit will get them a hefty fine, but all things considered when a problem just pops up like this you dont know where its at and you have little control over it. They are doing the right things.
They are finding water near the condensate storage tanks. This is water that is supposed to be used for emergency cooling, replenishing reactor feedwater, and overflow for a couple systems. It is potentially contaminated. It draws its water from the potable water system (typically in most plants), which means that the water going in is supposed to be clean. They need to check if they have a leak in there causing potentially contaminated water to go into the site's potable water system. I'm sure that was already done, at my plant it would have been done already at least. Anyways, condensate storage tanks arent always located inside the plant. It is very likely thats where the leak is. I'm not completely sure why they are getting tritium of all things as in a BWR plant tritium usually isnt your biggest worry. Nuclear plants have a corrective action process that a plant uses to fix problems. Anyone at the plant can put something in the process, it is federally mandated, and its one of those things that an employee cannot lose his job over. The system is very effective and allows the plants to 'self-police'. Finding and fixing a problem like this when the tritium leak was low would have been a low priority fix because the tritium levels were under limits previously. One of the actions they took was likely to install the new wells to find if the leaks were worse near potentially contaminated systems, which they did and found out it was worse. Now they are likely elevating the issue internally, which is why it was reported again to the NRC. So far, the plant sounds like they legally/procedureally done everything right. They made a huge boo-boo by having a PR guy tell people they have no underground piping that could carry contaminated water, it makes me think that guy never took or paid attention during the BWR systems class. The plant cannot be expected to prevent all accidents, but they are expected to mitigate accidents and issues to a minimal risk of safety to the public and to monitor and fix equipment which has repeat failures (things they know are breaking). Long story short, They are going to get investigated, and if this problem has been here longer than they say it has, they are in a bit of trouble. I Tritium isnt terrible in the water, as long as it doesnt get into drinking water. It's in low amounts that it will be diluted easily if it reaches a main water supply. It's still not good, but there are MANY worse things that could have leaked.