Plymouth Nuclear Power Plant operating on Diesel Generators for over 24 hours

Due to a power outage caused by winter storm Nemo, the Plymouth nuclear power plant in Massachusetts went into hot shutdown at 22:00 Friday, February 8th. The diesel generators that supply back-up cooling power came online. NRC--report # 48736

It was also reported by Cape Cod online that:

“The plant was at reduced power at the time of the shutdown because of a leaking reactor vessel safety relief valve, and it is likely (plant owner) Entergy will address that prior to returning the plant to service,” Sheehan said.

This article also states that the plant has enough fuel to run for more than a week.


It was later reported that 1 of 3 offsite power supplies was reconnected at 10:55 am on Sunday, February 10th.
Great news! Except that it only stayed on for 3 hours.

According to event report # 48739:

"On Sunday, February 10, 2013 at 1405 [EST], with the reactor at 0% core thermal power, all control rods fully inserted, and in cold shutdown conditions, the plant experienced a loss of off-site power. With Pilgrim Station aligned to off-site power via the start-up transformer (SUT), a fault on the 'B' phase of the SUT was experienced due to suspected falling ice striking the phase's insulator. This resulted in the tripping of the feeder breaker, ACB-102, and the loss of power to 4160 KV buses A1 through A4. Emergency Diesel Generators (EDGs) 'A' and 'B' auto-started as designed and are powering emergency buses.

"The loss of off-site power resulted in de-energization of both Reactor Protection System (RPS) channels resulting in a reactor scram signal and isolation of shutdown cooling. At 1418, shutdown cooling was returned to service. All other plant systems responded as designed. Station personnel are in the process of establishing back-up power in accordance with plant procedures.

...back to operating on diesel generators.

Does it bother anyone else that there is no mention of this on the non-stop coverage of this blizzard and it's aftermath? Let alone the leaking reactor vessel safety relief valve?

So the plant has been back on generator power for 24+ hours now. I sure hope this gets resolved very soon.

reply to post by Olivine


Great find. S&F

With the nuke plant down, where are the people getting thir power from? It seems the diesel generators are only there to power the cooling stuff for the plant to prevent a meltdown. Did the whole area lose power or are they getting it from somewhere else now?

It's no big deal and not an emergency.

Everything was shutdown as per procedure and is not dangerous. No need to report on the news if it isn't news.

I worked at The Cook Nuclear plant in Bridgman Michigan for a quite a few years and know the protocol for these type of things.

Everything is good and no need to worry.

reply to post by FortAnthem


I would think power is being re-routed from a different power generating station. I'll see what I can find. Thanks for your reply.

reply to post by mwood

Hi, Thanks for your knowledgeable comments.
I agree that it is not a screaming, all caps, run for the hills headline; but it is a sobering reminder of the the age and fragility of this nation's electric infrastructure.

wait! so they turn the nuke power plants off when it snows?? what good are nuclear power plants if we can`t use them when it snows?

Originally posted by Tardacus
wait! so they turn the nuke power plants off when it snows?? what good are nuclear power plants if we can`t use them when it snows?

According to the article, a huge icicle grew on one of the power lines causing a short which activated the automatic disconnects.

Probably could have happened at any power plant, causing an interruption in power. The reason its newsworhty here is because it forced them to use backup power to run the plant's cooling system to prevent a meltdown.

Its a good thing the diesels worked or there could have been some serious problems.

reply to post by FortAnthem


The best I can tell the New England sub-region NPCC power generation is from the following sources:
Natural Gas 42.0%
Nuclear 29.8
Coal 11.9
Hydro 7.0
Non-hydro renewables 6.2
Source

So, power must be coming from at least one of these alternative plants. As of 2 hours ago, Plymouth was still running on back-up generators. myfoxBoston

They better be glad this thing did not go full Fukushima on them. Or there would be some very big problems.... Good thing the back ups in place were working correctly.

Originally posted by FortAnthem

Originally posted by Tardacus
wait! so they turn the nuke power plants off when it snows?? what good are nuclear power plants if we can`t use them when it snows?

According to the article, a huge icicle grew on one of the power lines causing a short which activated the automatic disconnects.

Probably could have happened at any power plant, causing an interruption in power. The reason its newsworhty here is because it forced them to use backup power to run the plant's cooling system to prevent a meltdown.

Its a good thing the diesels worked or there could have been some serious problems.

Now i've heard everything.

Perhaps i'm very naive in my expectations of PTB, when it comes to what i think of as everyday common sense...but are Nuclear power stations' critical power supplies routed by OVERHEAD cables and not Underground cables?!!

That is just insane.

Hurricanes, snow and ice always disrupt overhead powerlines...whereas they don't even touch sealed UG cables...what the hell am i missing here?

And another question would be, why the hell are nuclear power stations not built deep underground into the sides of mountains, or at the bottom of deep shafts?

When they go critical and explode, as we've seen them do on occasion, they would be already be entombed from the start.

reply to post by Olivine


oh for a moment thought you meant the one in England , phew ..#
not good though.

reply to post by MysterX

No kidding!
If an icicle can cut power to a nuclear power plant, it really makes me wonder what sort of trouble we could experience if something truly rare were to happen, such as a huge solar storm.
Thanks for commenting.

@HelenConway
Sorry 'bout that--didn't mean to give you a scare. I should have specified which Plymouth in the title.

From what I read on The NRC Current Event Notification Report as of 11:08EST The Emergency was downgraded. They regained offsite power and the reactor is at Mode 3 of a Hot Shutdown. All systems reacted as they should have.

Link Below, Need to scroll part way down the list.

NRC Event Notification Report

What happens is any energy companies that operate coal fired power stations start cracking open 400 dollar bottles of champagne because there fancy competitors with the big fancy nooookleeear power plant cant sell any electricity so there demand has just gone upby however many percent.

And some dude driving a 500ton dump truck in a coal mine is probably getting a lot drunker than he usualy gets on account of all the over time he just got.

Pretty much it really.

reply to post by Pegasus2000


Correct. But then scroll to the bottom of the page you linked. Event #48739

The power was only restored for 3 hours when ice fell on the phase insulation of the start-up transformer. The power has been out since this happened yesterday afternoon, so they are back to running off the diesel generators.

I've been looking, but I don't see any recent reports of the power being restored yet.

According to a local Massachusetts radio station, off site power was restored to the plant around midnight. This is good news. I'm waiting on the news release from the NRC.

Even though power is back, the plant will stay offline while they repair the leaking valve mentioned in the OP.