Looking into the nuclear power industry can be like peering into a murky bucket – through a pail, darkly. Whilst I’m waiting for an answer to my Freedom of Information request about nuclear power generation in the United Kingdom, because EdF Energy won’t tell me themselves, I have been instead trying to get some information from EdF Energy about the St Jude’s storm of October 2013.
7th April 2015
You mentioned St Jude so to give you a feel of how we communicate information for something like this, we send out a note to newswires every time a station is offline, whether planned or unplanned.
In the case of St Jude, the station was taken offline due to debris from the storm causing a loss of power to the site. It was absolutely not connected to any form of flooding.
Our first statement is copied below
“Dungeness B automatically shut down both reactors after power to the site was cut off. The units are safely shutdown and the site’s own generators are providing power to the site post shutdown. The station is liaising with National Grid regarding returning the power supply.”
And we provided a further update here: http://newsroom.edfenergy.com/News-Releases/Dungeness-B-offline-bb.aspx
And later on another update here: http://newsroom.edfenergy.com/News-Releases/Dungeness-B-update-bc.aspx
A few days later we issued a background note to explain in further detail what had happened.
Throughout the day on 28 October we gave numerous TV and radio interviews to explain the nature of what had happened. As above – it was not related to any flooding or water ingress – a piece of debris stopped power to the site and as a precautionary measure the reactors were taken offline.
There’s plenty of information available online. We publish regular updates on our website and I would recommend you exploring websites such as DECC and ONR who publish a quarterly update for any further information.
Good luck with your research
Thank you for your reply.
In the “background note” of 31st October 2013 :-
Most of the information given is background information, and does not
convey information about what happened between 27th October 2013 and
when the two nuclear reactors and their power generation turbines came
By the way, the use of the expression “single failure” in this
sentence does not make sense : “The on-site electrical distribution
systems are capable of performing essential safety functions even if a
single failure occurs.”
There is only one statement that indicates what actually took place :
“If loss of off-site power happens – as it did on October 28 – the
power station is capable of operating independently until grid
connections are restored.”
This is not the level of detail that answers my request for a formal
report of what happened.
(a.) Deliberate shutdown or “trip” shutdown ?
It is not clear from this background note whether the nuclear reactors
were shut down deliberately through intervention, or as a result of a
“trip” from rapidly changing power conditions experienced at the
“shared turbine house” (power island).
Just as there is safety control equipment which should start up
on-site diesel power generation automatically should the external
connection to the National Grid be lost (“There are several sets
(groups) of diesel powered generators designed to provide power to
safety critical systems, which will automatically start when the grid
connection is lost.”), I would expect safety control equipment should
be in place to shut down the nuclear reactors automatically should
power not be available or the power supply is fluctuating rapidly.
These two general statements are made, but it is not possible to
determine which was the particular case : “The decision is always
taken to shutdown the reactors if the site loses grid connection,
electricity is then provided by the on-site diesel generators which
power the essential on-site plant.” and “With delivery of consumables
to site, successful post trip cooling of the reactors can be
So, what was the actual order of events ? I expect there were some
problems with the supply of power from the National Grid (owing to the
“debris” mentioned). I expect that what happened next was that the
emergency on-site diesel generation equipment started up
automatically. I don’t know, and I am not told in your “background
note”, whether all of this equipment started up correctly. I don’t
know, as your report does not say, whether the on-site power
generation was successful in generating enough power to keep the
carbon dioxide coolant pumps for both nuclear reactors in operation. I
don’t know, as your report does not say, whether the nuclear reactors
were shut down automatically, or as the result of a station management
(b.) Diesel and water supplies
The “background note” does not state whether there were sufficient
supplies of water and diesel fuel on site to last for 24 hours or
longer. It also does not say how much diesel fuel and water needed to
be brought on-site for the remainder of the shut down period until
first one and then the second nuclear reactor were brought back
(c.) Nuclear reactor start up
The “background note” does not state the reasons for the time it took
to get the nuclear reactors restarted. For example, were the coolant
pumps (the physical pumping equipment or the electrical equipment)
damaged in the incident ?
These details would be most useful to know.