Talk:Magnox

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Military Plutonium production[edit]

On load refuelling and miltary use. I strongly believe this linkage is NOT correct, and so I've deleted it. The issue of military use of material from the civil programme was checked out with the then chairman of CEGB many years ago - there was a special short-dwell facility at Hinckley (???) but it was never used. The two AEA reactors (Chapel Cross & Calder) where military Pu production was more of an issue, were not designed to be fuelled on load, I recollect... Overall, on-load refuelling was a special requirement of CEGB to enable commercial operation. Linuxlad 09:29, 26 Nov 2004 (UTC)

It's a moot point whether non-commercial and uneconomic are the same thing - some people will pay a lot for weapons grade plutonium! Linuxlad 21:03, 23 Jan 2005 (UTC)

You are correct that Chapel Cross & Calder don't have on-load refueling capability [1], so I will remove the sentence I added: "This was particularly useful for short fuel cycles used to produce weapons-grade plutonium-239".

But on the more general point of military use of Plutonium from CEGB power stations, Ross Hesketh (ex-CEGB) said that 5.4 tons of plutonium was supplied to the US between 1960 and 1970 under the Mutual Defence Agreement:

"This included the entire production of plutonium from all the UK civil nuclear power stations, up to April 1969, according to official sources.".

See "Nuclear safeguards in Britain" in Scientists for Global Responsibility Newsletter No. 19. See also Ross Hesketh's Times obitury.

Given these contrary views I'd suggest not saying anything about which reactors were used for military plutonium. I don't think this is very central to the article anyway.

There was the 1962 "Nuclear Weapon Test of Reactor-Grade Plutonium" using Magnox produced plutonium: "The plutonium was provided by the United Kingdom under the 1958 United States/United Kingdom Mutual Defense Agreement" [2]. Would have come from Chapel Cross or Calder of course being a 1962 test. Is it worth including this rather interesting item in the article?

NB A side issue: HSE NII Safety Review report - Table 1 says Hunterston A is licensed by BNFL (like Chapel Cross & Calder) unlike the other ex-CEGB units licensed by Magnox Electric. Anyone know why? - Rwendland 00:45, 16 Jun 2005 (UTC)

Lack of secondary containment[edit]

Lack of any secondary containment on UK's gas cooled reactors is an obvious major criticism, and should be covered in the article. I'm interested in the detailed justification for no secondary containment, but it seems hard to track down. Here are the the relevant references I've found so far, mostly too detailed to link from in the article:

Be nice to track down a detailed safety case discussion, but I can't find one on the [HSE/NSD] website; anyone know where one can be found? - Rwendland 14:27, 16 Jun 2005 (UTC)


I can't see that it is such a big issue - the later gas-cooled reactors had Reinforced concrete pressure vessels, with boilers enclosed in the RPV. The maximum breach size was quite small, and the loss of CO2 can usually be made good. Provided the reactor trips, and the boilers are fed, natural circulation will take heat away if the system remains at presure - and in the Magnox designs natural convection will also suffice at atmospheric pressure IIRC. These reactors have many benign features because of their relatively low power densities.Linuxlad 19:17, 16 Jun 2005 (UTC)

There's no secondary containment on the Magnox - in terms of worst credible accident it wasn't felt necessary at the time. The early steel-vessel ones probably wouldn't be built today. In the later concrete ones the pressure vessel was approved as the containment structure. By way of contrast, the AGR does (contrary to some reports) have a containment building, but the PBMR won't have.
Interesting too to note that, contrary to most reports, the RBMK does have secondary containment. But the top plate is part of this containment. The builders didn't believe that any credible event would lift it. Andrewa 04:13, 20 June 2007 (UTC)[reply]

discrepancy over first commercial reactor[edit]

From Nuclear Power:

On June 27, 1954, the world's first nuclear power plant that generated electricity for commercial use was officially connected to the Soviet power grid at Obninsk, USSR. The reactor was graphite moderated, water cooled and had a capacity of 5 megawatts (MW). The second reactor for commercial purposes (1956) was Calder Hall in Sellafield, England, a gas-cooled Magnox reactor with an initial capacity of 45 MW (later 196 MW).

Yet this page claims that Calder Hall was the first commercial plant. Which is correct? --BWDuncan 18:05, 19 April 2006 (UTC)[reply]

Depends on how you phrase it! Calder Hall was the first purpose-designed commercial reactor, producing a significant amount of power for about 40 years (although still secondary to producing military plutonium in its early years). The Obninsk reactor was a research/military reactor, hooked up to produce some power, as I recall it shut down within a few years. I'll try to re-find some references and report them here, but it might take me a while. Rwendland 08:26, 20 April 2006 (UTC)[reply]
Finally remembered where my notes on this were: see Talk:Sellafield#First_commercial_nuclear_power_station.3F for a pretty full discussion. It's quite tricky to write a balanced consensus summary, but I'll have a go when I have some more time. Rwendland 23:09, 21 April 2006 (UTC)[reply]
Also found out that TIME magazine described Calder Hall as first to achieve atomic power on a serious scale solving a fuel shortage for her industry - article "First Nuclear Power" TIME magazine, 29th October 1956. [3] Rwendland 17:20, 9 March 2007 (UTC)[reply]

Newspaper copying text[edit]

Not a big deal, but interesting to note an internet "newspaper" (www.24dash.com) copying some text from this article! Direct copied text in italic:

In its early life Calder Hall was primarily used to produce weapons-grade plutonium, with two fuel loads per year. Electricity production was a secondary purpose.
From 1964 it was mainly used on commercial fuel cycles, but it was not until April 1995 that the UK Government announced that all production of plutonium for weapons purposes had ceased.[4]

Don't object, as at least this is more factually correct than other recent reports that fail to say Calder Hall's primary purpose was military, and just go on about power production. Rwendland 14:01, 30 September 2007 (UTC)[reply]

Move to Magnox nuclear reactor[edit]

Better name for article may be Magnox nuclear reactor ? Then the Magnox section can be amended. - Rod57 (talk) 11:17, 18 August 2011 (UTC)[reply]

Magnox reactor working in North Korea[edit]

See this article: North_Korea_and_weapons_of_mass_destruction#Plutonium. States NK is still running a Magnox reactor, implying the statement about the last remaining Magnox reactor being in the UK is therefore untrue. John a s (talk) 08:40, 13 December 2012 (UTC)[reply]

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Windscale fire[edit]

The "Windscale" section says "Graphite is flammable and presents a serious safety risk. This was demonstrated on 10 October 1957 when Unit 1 of the now two-unit site caught fire," but the article linked from that paragraph says it was the fuel that caught fire, not the graphite. The page about the fire says, "Inspections showed that there had not been a graphite fire, and the damage to the graphite was localised, caused by severely overheated uranium fuel assemblies nearby."

So while the use of graphite certainly contributed to the accident, the flammability of graphite did not contribute as it did in Chernobyl; it was the untested annealing process they were using, which caused the fuel rods to overheat and catch fire. —Sean r lynch (talk) 20:57, 14 October 2023 (UTC)[reply]

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