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Nuclear Plant Taken Down In Anticipation of Snowstorm
mdsolar writes Pilgrim Power Plant in Plymouth was taken offline in anticipation of the weekend snowstorm. According to a statement from Entergy, the owner of Pilgrim, the plant was taken off line in preparation of "a potential loss of offsite power or the grid's inability to accept the power Pilgrim generates." This is the second time this season the plant has been shut down due to storm conditions. On January 27 the facility was taken offline after the two main power transmission lines were knocked out by blizzard conditions. Although the transmission lines were restored within a few days, the plant remained offline until February 7 at which time it was reconnected to the grid.
https://en.wikipedia.org/wiki/...
Right...
Sounds like this is a "preventative measure".
Normally there is some time between neutron capture and actual nuclear fission (I have heard a figure of 15 minutes). This means that even if the control rods are slammed in when the power transmission lines were cut the previous heat load would still be generated for a period of time. Often this means resorting to drastic measures to reduce the neutron flux to zero ASAP (certain salts are added to cooling loops which achieve this but requires a good flush to get rid of).
Controlled shutdown means the reactor can be restarted in "a couple of hours"
Emergency shutdown means the reactor can be restarted in "a couple of weeks"
Burnt once, twice shy...
Nuclear plants of the design mentioned in the article must legally have offsite power to continue operation. As soon as offsite power is lost, the plant is required to shutdown. An emergency shutdown is more paperwork than a planned shutdown such as this.
The reason for this is that in an accident scenario, you would like to rely on offsite power to run your emergency coolant pumps for this particular design.
Newer reactor designs don't have this issue, but this is a pretty economic decision considering an emergency shutdown if/when the offsite power does eventually trip. The grid seems pretty unreliable based on past experience, as the article even notes.
Nothing that mdsolar wrote was untrue, and it didn't even sound judgemental.
To be fair, the title was changed by samzenpus. mdsolar's submittal title said something like "unreliable nuclear plant shut down....". An attempt to mislead on the reason for the shutdown.
True.
Loss of offsite power is an analyzed condition and the plant's license requires it to shut down when offsite power is lost. The safety analysis shows that the plant is in a higher risk level as it becomes reliant on its emergency diesels should another severe accident occur at that time. (Even though in those situations, the plant is designed to still be able to cope with all design basis accidents)
There is no license requirement to shut down in anticipation of a loss of offsite power, and the plant is designed to handle it safely.
Plants keep running through major storms all the time. This is particular to the local grid.
You are attempting to discredit this story by maligning the submitter.
The story is FUD. That's mdsolar's MO; post transparently stupid, fear mongering stories about nuclear power. He deserves to be maligned; he's earned it.
Maw! Fire up the karma burner!
I'd like to correct my statement above which says "There is no license requirement to shut down in anticipation of a loss of offsite power".
Actually, there is a generic requirement to monitor grid reliability, and an unreliable grid determination could force a licensee to shut down. That is typically based on actual performance, not on anticipation, but I wanted to be accurate.
Pilgrim is a reliable station still going strong after many years.
Lol @ reliable. Pilgrim has been on the NRC's worst-ten shit list for a few years now.
The same day the storm hit, the NRC sent Pilgrim a letter.
http://pbadupws.nrc.gov/docs/ML1502/ML15026A069.pdf
Overall, the NRC has determined that your act ions have not provided the assurance level to fully meet all of the inspection objectives and have correspondingly determined that Pilgrim will remain in the Degraded Cornerstone of the Action Matrix by the assignment of two parallel White PI inspection findings. [Green, White, Yellow, Red, in increasing order of severity] [...] . Additionally, for one of the
root cause evaluations, inspectors determined that Entergy failed to investigate a deficient condition in accordance with corrective action program (CAP) requirements to ensure they fully understood all of the causes of one of the [four unplanned] scram events [that happened in 2013].
Reliable != multiple unplanned SCRAMs per year.
Anyways, on January 27, while the reactor was SCRAMing, these three things happened:
The High Pressure Coolant Injection System had to be secured due to failure of the gland seal motor.
The station diesel air compressor failed to start.
One of the four safety relief valves could not be operated manually from the control room.
Those safety relief valves are the ones that get used to vent pressure after the coolant injection system fails.
Pilgrim has problems. On top of all those problems, locals are spitting mad because the disaster plans fail to include scenarios like "giant blizzard shuts down all the roads and nobody can evacuate."
[Fuck Beta]
o0t!
The snow is light-weight powder and we haven't had a thaw/freeze cycle, so when the wind hit makes no difference. Only about half of the roofs have been flat. There's a huge multi-building apartment complex down the street from me that evacuated because one building did have a roof collapse. The roof was nearly as pitched as my own. A number of others in other towns with similar style roofs have had the same problem.
Wind can relocate snow, but high wind doesn't mean roofs or anything else gets cleared off. It just means the snow gets put wherever nature feels like it. Get some gloppy slushy snow and that stuff will stick to anything like glue. Your panels would be doing about as good as our roofs, which isn't very good. The best part is that houses with panels would have to bear the weight of the roof, the weight of the panels, plus the weight of the snow. Not to mention the wind when it really gets ripping up here will want to tear those panels right off. Wind gets strong enough here to remove roofs if there's enough imperfection in them, or shoddy maintenance, or stuff attached to them that wasn't meant to be there.
Actually the earthquake damaged part of the emergency cooling system and thus prevented effective cooling that would have averted a meltdown. This did not become apparent until months after the disaster when it was possible to examine the pipes and valves that make up the system. They were pumping water in with fire engines, but it was being syphoned off by a broken valve and never made it to the reactor. Even if the valve had been okay, pipes further down were leaking anyway.
Search YouTube for NHK documentaries on the subject. NHK is like the Japanese version of the BBC, pretty reliable and they have done a lot of work examining what went wrong at Fukushima. Their documentaries are available in English.
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