Posts by Alan Brown

Re: The footrest

The UK's universities are already falling out of the top groups

Of course, the people running those Universities don't see it that way because there are still a few at the top but the critical mass has already gone and the much-vaunted Russell Group is on shaky ground

An yes, this has everything to do with Brexit - These outfits were top tier because they attracted top international talent which is now gravitating elsewhere

Re: 110%

On gas turbines, 100% is usually the continuous rating where exceeding it comes with rapidly dimininishing lifespans due to heat/blade stress in the turbines

On electric motors, 100% is usually the continuous rating where exceeding it comes with thermal penalties and you risk melting down the windings/insulation breakdown if the motor overheats(*)

(*) My ancient EV's motor is rated for 24kW continuous, 48kW for 5 minutes or 64kW for one minute. People have tweaked it to get significantly higher output (over 100kW) by bumping up cooling flow and/or limiting peak power duration and/or tighter thermal management - the ultimate limitation is how much torque the gearbox can transmit before self-destructing - it's impressive for being a bog-standard heavy-duty forklift motor at heart)

Re: Aircraft systems & resilience

"But, but, the Salesman said it could....."

Got that in writing? Thought not.

Re: Incredibly delicate technology

I've always wondered about the opposite course of action - having some way of blowing the pitot out using pressurised air (after isolating the sensor if they can't handle pressure)

It's one of the ways of cleaning them when they're off the aircraft, so would essntially be a way of automating the procedure

The problem (of course) is that on an aircraft there are many ways these days of measuring speed but what counts for staying aloft is indicated airspeed (IAS) and the pitot is one of the few methods to accurately give this information most other methods give ground speed. (IAS varies not only with wind, but altitude - at 30,000 ft a plane travelling at 700km/h will show a IAS not much above ground level stall - because the lift is quite low at these altitudes)

That's why pitots - despite all their disadvantages - are still used. Nobody's come up with a better instrument. If they do, the world will beat a path to their door

Re: Incredibly delicate technology

"As it’s a safety critical thing it should be counted in and out, flashing lights and beacons are the warning that it’s still attached and not in its box."

One of the Brisbane incidents was BECAUSE they're counted in and out

The covers fitted belonged to the airport, not the aircraft, so when the locker count was OK, the aircraft took off with 2 airport-owned pitot socks still attached

I suspect the answer in this particular case is to make the red dangly "remove before flight" things even longer (as in "long enough to reach the ground" or "long enough to clip to the nosegear") , so they're impossible to miss when doing a walkaround or during pushback - even in the dark

Re: recuperator == heat exchanger

"Why they think that using supercritical C02 is better than water is not explained by this article. "

in short: Corrosion

All else being equal, Water-based systems are higher maintenance

Re: For the scientists -->

MSR nukes are the ideal heat source for this

They're currently positioned to enter service using steam, but that's mainly because it's a fatal mistake to introduce too many new technologies at once

Re: Sadly, in the UK, no one is held responsible for software errors

"Perhaps TPTB might try and wriggle out of prosecutions"

Several people DIED as a result of their actions and they seem to be working on the principle that if they drag it out long enough, most of the rest will too

Post Office needs to be on the hook for corporate manslaughter by harrassment - and if it's proven that senior manglement did know of the issues then they need to face personal culpability

Re: Preaching to the chior

"...the team responsible for the specification and procurement are well COACHED by those tendering."

There, fixed that for you - and it's closer to what happens, in my experience

"It is introduced to the reactor vessel as a liquid and drained as a liquid"

The entire loop (pipework, reactor and heat exchanger) is wrapped with electrical heaters. Freezing in the loop is permissible and part of the design criteria (it's used for things like isolating sections of the pipework)

Brayton cycles are possible and likely to be used in the long term but steam is understood NOW

Re: Water

Using thorium divorces civil nuclear powerr from a dependency on (bloody expensive) U235/plutonium and will expose weaponsmaking systems to the full force of limitation treaties

That's why there's been so much FUD about MSRs. They don't need U235

Re: Water

they also eat thorium - which is the primary waste product of rare earth mining,

So much so that this changes the world's rare earth mines into thorium mines with a rare earth side gig

_VERY_ cheap fuel ($100-200/kg vs $50-75k/kg) and a benefit for other industries

There's enough thorium in old coal power station ash slurry to be wrth mining that too - which would essentially fund cleaning up such sites

water wouldn't even be in the secondary loop, eeither tertiary or quartenary

The advantage of this is that a steam explosion - is JUST a steam explosion (anything nuclear stays in the reactor building and anything that gets out of the primary loop only goes a few inches before freezing solid)

It's pretty clear that China's work on these units is intended to make drop-in replacements for coal burners in their existing recent power stations and they're chasing scaling from the 2MW Wuwei experiment to 100MWe before jumping to 1000MWe

Re: No shit, Sherlock

The point of the reprocessing setup was that only a small amount actually needed to be done (only to remove non-gaseous poisons which might stop the reactor and only if they built up to levels actually needing to be dealt with)

In most cases it would be easier to knock a few points off the overall economy of the reactor and simply enlarge it a little/overfuel it slightly (the reactor was continually fuelled as needed, rather than being loaded with 12 months supply at startup) and calculations for larger designs pointed to the processing only being needed from about 10-15 years in

The primary reason this is finally getting some attention is that China's replicated the MSRE at Wuwei and has had it running since last October whilst simultaneous preparing a 100MWe larger unit (the ORNL scaled up proposal). It's no longer possible for the US establishment to pretend it doesn't exist

Re: No shit, Sherlock

Hint1, Salts are at the bottom of the reaction energy curve.

Hint2: Flourine is incredibly reactive but flouride salts are extremely STABLE

Hint3: Uranium hexaflouride

Re: No shit, Sherlock

"All salts are corrosive, incredibly so in their liquid forms"

Only if they become ionic items (ie, dissolved in something else)

The whole point of molten salt is that the salt itself is the liquid (melts at 450C) and the FliBe used wasn't water soluble

ie: This isn't a "salt water loop", the salt IS the loop, running at 650C and capable of excursions out to 1000C quite safely

Re: "David JC MacKay", "Sustainable Energy"

WHEN it happens, geology shows that the change is rapid and extreme

The Permian extinction event final act played out in less than a decade (possibly less than 18 months)

Re: "David JC MacKay", "Sustainable Energy"

"As an aside, carbon capture from the air is a complete white elephant."

It has its place, but it's only viable with nuclear power and for specific applications (long haul air travel)

in virtually all other scenarios, cables or batteries will be a cheaper/better option

It's the same issue with selling hydrogen as a replacement for retiuculated gas - why would anyone buy gas that costs 3-5 times as much per kWh as electricity?

Re: Nuclear power has "zero emissions"?

"What about the waste heat from the cooling towers"

What about it?

By comparison with the blanket effect of CO2 emissions trapping petawatts of reflected sunlight it's down in the noise

You'd need tens(hundreds) of thousands of such plants to have the same effect as tweaking CO2 levels

Re: Volcanoes ?

The one that was developed was shitcanned by Nixon in 1972 because it would have allowed civil nuclear power to divorce itself from (very expensive) plutonium/U235 and thereby expose the military systems to limitaion treaties as they lost "dual purpose" production exemptions

Re: Volcanoes ?

250-300C is not high quality steam. It's not even "dry" steam

At that temperature you're facing major erosion problems on your turbines and consequent very high maintenance costs

Geothermal water is invariably highly silicated too, which comes with its own sets of problems

Re: Volcanoes ?

"You can do it anywhere but, outside of helpful locations, the effort needed to drill the hole and maintain it is uneconomical"

What people fail to appreciate is that rock is a VERY good thermal insulator and pulling heat out of the ground invarably ends up not being replaced as fast as it's extracted

Just about every geothermal field created has ended up losing 20-25% output in the decade after construction

Re: Lack of Uranium?

Making plutonium in a power reactor is a non issue. It's multiple isotopes and virtually impossible to separate from used rods

The bigger problem is that ALL solid fuelled reactors can have depleted uranium rods stuck in them briefly to produce weapons-grade plutonium. These aren't "power" rods but the solid fuel design facilitates doing it

This underscores that the critcal part of the weapons proliferation cycle isn't "uranium" or "enriched uranium" but DEPLETED uranium

Making a uranium bomb is essentially uneconomic (the materials costs is about $40-100 billion per unit. It's cheaper to buy your enemy).

You need depleted uranium because a nuclear weapon actually needs very low radioactivity components, or it is likely to go off prematurely and natural uranium produces too much Pu239

Ditto trying to make bombs out of thorium -> U233. It makes u232 as part of the process - in sufficient quantitiy to be deadly to handle (gamma emission) and be an excellent fizzle maker(*). Attempting to separate U232/U233 wiould require a centrifuge farm 100 times larger than a natural uranium one AND it would need heavy lead shielding to protect the operators - all a bit noticeable really

(*) Teapot Dome is about the most sucessful one ever and it produced half the yield expected from what you'd see if the U233 had been replaced with U238 or tungsten

China's working on breeders - thermal breeders using thorium. Once working, Proliferation problem == solved and anyone continuing to enrich uranium is essentially exposed as doing so primarily for weaponsmaking purposes

(not to mention it also nobbles the US petrodollar hegemony. They're playing a long game)

Re: There's plenty

Peak Oil passed 20 years ago worldwide and around 1971 in the USA

It's not "peak level of extraction", it's the peak of EASILY ACCESSED, "light sweet crude" oil - ie, the end of the low hanging fruit

Oil is steadily costing more in energy to extract (tight oil) or refine (less sweet crudes)

In real terms, oil extraction costs about 20 times what it did in 1970 but oil prices (inflation adjsuted) are only about 3 times what they were in 1970. Some of that has been helped by imroved refining processes but profit margins are lower than they used to be

The industry uses an energy ratio - barrels expended vs barrels delivered to try and explain this. It was about 1:100 in 1900, 5:100 in 1950 until the 1980s.

Alaskan tar sands are about 1:3 and bakkan shales are about 1:6 whilst deepwater rigs end up in the 1:10-12 range

There's ~5000 tons of thorium available PER MINE per year from most rare earth mines and a few hundred thousand tons buried in the Utah desert as a starting point

Fixating on Uranium misses the other answers which already exist

Especially that pernicious dihydrogen monoxide, it's in EVERYTHING

Re: "Why is anyone worried about the plant at Zaporizhzhia being shelled"?

You'd actually need a lot of shelling to achieve that

Mostly it will just annoy the staff because the walls will need to be repainted

PWR containment buildings are insanely strong

Re: "Well, an extinction-level event is on the horizon..."

Look at what happened 250 million years ago at the end o the Permian era

We're rapidly closing on a repeat of that

Warm blooded creatures cannot survive global oxygen levels dropping to 11-12% and most reptilians won't survive either

Re: Deaths are not the only metric

Vodka fuelled playing with a design whose primary purpose was plutonium production and (like Sellafield) had insufficent safeguards in place. The difference is that Sellafield had those filters, otherwise it would have been equally as bad (Sellafield was a military reactor whose ONLY [purpose was plutonium production)

There were lots of objections in the west to Chernobyl and its ilk being built in the first place BECAUSE of the susceptability to the exact failure mode which happened in 1986

Re: Deaths are not the only metric

You missed the ash slurry lakes that coal fired power stations produce (particularly in the USA)

The TWO biggest US environmental disasters so far this century have been ash lake dam breaks

Re: Deaths are not the only metric

Tritium levels in the water tanks onsite at Fukushima are lower than natural levels in many parts of the world (including most of Australia) and well below even the strictest limits for drinking water

Re: "Of all the non-carbon energy options we have"

"Yes we should be putting some real research into Thorium fuelled MSRs."

China is. Wuwei 2MW test site has been running on thorium since October 2021

It's a rebuild of the 8MW ORNL MSRE - they skilled the U235/U233/plutonium stages though

There's a 300MWt (100MWe) electrical breeder test plant being built beside it.

If that works as expected (and there's no reason to expect it not to) I'm expecting to see 3000MWt dropin replacements for coal burners by the end of the decade

Chinese power stations have been built with clear provision for "something else" beside the turbine halls for a while. They'll sell this to all comers too

It's not JUST about electrical generation in developed countries. Developing countries are badly hobbled by lack of resource. This will allow them to play catchup without being crippled by oil prices

Re: Bang On - except the death stats

Minimata bay

Re: single family dwelling vs apartment/condo counts anyone

Once you eliminate gas heating, how much battery capacity will you need?

This is the problem that all the chancers pushing renwables keep (deliberately) glossing over

The South Australian power cuts were a direct result of a short-term failure in wind being too short for the operators to make enough money to pay for firing up the OCGTs - so they didn't fire up the OCGTs (until someone agreed to pay the bill, 6 hours later)

In addition merely HAVING the backup generators is a huge expense. They don't exist in some kind of stasis field until needed and are a high maintenance item which needs to be tested regularly

"SMRs potentially can speed up adding new nuclear capacity, but otherwise reactors take a long time to build."

MSRs don't require stupidly large/expensive containment vessels and buildings as they don't need to contain a steam explosion. Build cost for a 3000MWt design is estimated at 80% lower than current nuclear designs 5 years or less to complete one and - most importantly - the ability to fabricate most parts on a production line

SMRs are only being proposed "Because they're British!" - they're a bloody stupid idea

"A nuclear plant can produce that much"

A _SAFE_ nuclear plant could be located similarly to Battersea and provide district heating too.

water-moderated solid fuelled designs were a laboratory glassware proof-of-concept, not an industrially-safe scaleable prototype - and most non-water-moderated designs currently in use are built around repurposed weaponsmaking processes, not purpose-built civil power designs

The USA's only purpose-built, proliferation-resistant design intended from the outset for scalable civii power generation was stomped on in 1972 because it was "too sucessful" in testing