The UK's Small Modular Reactor Competition

[Chris Hogg]

Bulb wattages vary widely. Here's a big one of 3 kW

. But modern LED arrays probably use much less. But in older lighthouses, you also needed to supply the power for turning the huge (and technically and aesthetically rather beautiful IMO*) Fresnel lens systems**. Although the bigger ones typically weighed several tons, they floated on a bath of mercury so actually required very little effort to turn them once the initial inertia had been overcome***. In older, manned lighthouses, this was manpower, literally. The lighthouse keepers would regularly (every few hours) have to wind up a falling-weight system that rotated the lens (think Grandfather clock), but later, on unmanned lighthouses the power had to come from another source, usually electric, from diesel generators and batteries IIRC.

• Images here The bigger and heavier ones stand several feet high.

** A rotating lens system was essential, to give the appropriate number of flashes per minute that identified the particular lighthouse, rather than just switching the lamp on and off repeatedly, which as we all know, shortens the life of the bulb dramatically. The Fresnel lenses were very efficient at gathering the maximum amount of light from the bulb and focusing it where needed. Ranges were typically 20 miles or so, depending on lighthouse height, bulb power and atmospheric conditions. *** There used to be the national lighthouse museum run by Trinity House in Penzance some years ago, and they had several in a range of sizes. The biggest floated in a mercury bath and could be turned with one finger. But Trinity House closed the museum in 2005 and I think the collection was broken up and dispersed. An absolute tragedy and disgrace!

[GB]

Not a very powerful light bulb, though, according to the figures on WP. Even allowing for it flashing on and off, so it's not powered all the time, you are looking at a couple of hundred watts, maximum.

[charles]

in most light houses, 'flashing' is created by a revolving lens assembly. That revolving would need a motor - more power.

[Nightjar]

Although they are described as lighthouses, the vast majority of the Soviet nuclear powered lights were little more than navigation beacons.

There is one that often appears in photos, which does have all the gubbins of a full blown lighthouse and that has radiation warnings, but it also has diesel generators and large fuel tanks, so the reactor was obviously not there to run the light. Perhaps it ran a backup system to call for attention if the main power failed.

[GB]

True, indeed. So, I don't see how one of these generators could produce anything like enough power? They seem to be in the range 10-100 watts.

Solar power makes more sense nowadays, even with redundancy built in to allow for degradation due to dust build up.

[charles]

Not in winter north of the arctic circle

[The Natural Philosopher]

Solar power makes no sense at all. Its completely unsustainable

[GB]

How much does a TNG cost? (£100k? £1m? £10m?) Then compare that to half a dozen solar panels.

You probably ought to read the thread before commenting on it.

[charles]

Solar panels don't work at night. That's the time most people wany to turn their lights on.

[Chris Hogg]

Many buoys these days are fitted with solar panels to power the electronics, especially the scientific buoys used to record maritime conditions such as wind speed, wave heights and temperatures. Even lighthouses have them. What does surprise me is that they survive the conditions, and don't get short-circuited by the salt water or simply crudded up by salt deposits.

Two scientific buoys in the Channel off Plymouth:

and the Bishop Rock lighthouse west of the Isles of Scilly

(solar panels up around the lantern below the helipad), Nab Tower off Southampton and Royal Sovereign, off Eastbourne

[The Natural Philosopher]

Yep. There its not a question of generating large amounts of power, so batteries and solar is cheaper than cables to shore. atomic batteries, or regular visits to replace primary cells - nuclear or not.

Its pretty piss poor in the Arctic circle in winter tho.

However that's not what I meant. I meant that when you need to generate serious amounts of power, reliably, solar doesn't cut the mustard. The batteries get too huge and too expensive, and the whole thing gets to be about the battery, and you might as well have something else instead.

"In 1973, the oil lamp was changed to a hyper radial rotating 400W light, when *electricity was brought to Bishop Rock*. The lamp emits two white flashes every 15 seconds and has an intensity of 600,000 candela. It has a range of 45km."

It may have solar panels, but it looks very much as if it has an undersea cable powering it, since solar panels were not in existence in

1973.

I accept that the other two are currently solar powered, but they are low pwer, and close enough to shore to be easily serviceable when anything goes wrong

[Andy Burns]

Yes, but that hardly makes them candidates for a UK modular reactor ...

[The Natural Philosopher]

OTOH a pair of reactors (for redundancy) makes a lot of sense for remote island communities.

is interesting. Note that undersea interconnectors can and do fail.

IN the end its a cost benefit calculation. Whether reactors, interconnections with gas backup, diesel or WHY is actually the cheapest way to supply a small isolated community with power.

[Chris Hogg]

No argument there!

The phrase 'electricity was brought to Bishop Rock' is misleading. It means 'when the Bishop Rock was electrified'. The Bishop doesn't have an undersea cable. When the paraffin vapour lamp was replaced by incandescent electric lamps (1500 watt, 240 volt) in 1972/3, they were powered by diesel generators. The lamps were subsequently changed in the early 1990's, to the two 400 watt lamps you mention. At that time, when full automation was being planned, solar power was considered but it was concluded that they wouldn't generate enough power. New generators were installed, running intermittently and charging batteries. Fuel is stored on-site, enough for 18 months, topped up every 6 months by supplies helicoptered in. Around 2008, consideration was being given to using 'alternative energy sources' to reduce the lighthouse's use of diesel power. I imagine the solar panels visible in that photo are the result, probably charging the batteries when the sun shines, with the diesels doing it when it doesn't.

Source: 'Bishop Rock Lighthouse', Elisabeth Stanbrook, Twelveheads Press, 2008.

[tony sayer]

I knew it was you who wrote the even before i looked see who had;!....

How sadly predictable:((...

[The Natural Philosopher]

Well yes.

Of course te reactors are generally 'sealed fir life' so its pretty hard to actually get he material out without some pretty specialised kit, and you would either have to do that onsite, or steal the whole 1000 tonne reactor....

And if you start dismantling a scrammed reactor, you have better be quick or very protected, cos the gamma is gonna fry you in an hour

[Tim Streater]

Perhaps harry, with all his nuclear expertise, can explain how to get radioactive stuff out (without killing yourself, that is).

[newshound]

I'm pretty relaxed about terrorists taking on either a full sized or a small modular reactor. Knocking any power station off the grid is pretty easy of course, but I reckon there are far softer targets around than a reactor pressure vessel (or other sensitive parts). And I think we can be reasonably sure that anyone googling too assiduously for details will get ....noticed.

[GB]

Charge batteries during the day.

A TNG does make sense along the North coast of the USSR, where it's dark for months on end in the winter.

[GB]

It's odd to turn diesel power into electricity, with all the losses that implies, and then just use the electricity to heat up an incandescent light.

The idea of paraffin vapour lamps sounds much more thermodynamically efficient.

At that time,