{"id":1761,"date":"2023-10-26T12:28:12","date_gmt":"2023-10-26T12:28:12","guid":{"rendered":"https:\/\/wp.ccnr.org\/?page_id=1761"},"modified":"2023-10-26T12:28:19","modified_gmt":"2023-10-26T12:28:19","slug":"thorium-reactors-back-to-the-dream-factory","status":"publish","type":"page","link":"https:\/\/wp.ccnr.org\/fr\/thorium-reactors-back-to-the-dream-factory\/","title":{"rendered":"Thorium Reactors: Back to the Dream Factory"},"content":{"rendered":"

Thorium Reactors:<\/strong><\/span><\/h2>\n

Back to the Dream Factory<\/strong><\/span><\/h2>\n

by Gordon Edwards, July 13, 2011<\/strong><\/h4>\n

\u00a0<\/em><\/strong><\/p>\n

The Nuclear Dream Factory<\/em><\/strong><\/p>\n

Every time a nuclear power reactor idea doesn’t work out, and ordinary people get down-hearted and\u00a0start to doubt the magnificence and\u00a0benificence of nuclear energy,\u00a0nuclear proponents rush back to their well-stocked dream factory to fetch another idea — one\u00a0<\/em><\/strong>that is\u00a0sufficiently unfamiliar and sufficiently untested that ordinary\u00a0<\/em><\/strong>people have no idea whether it is good or bad, safe or dangerous,\u00a0<\/em><\/strong>feasible or foolish, or whether the almost miraculous claims made\u00a0<\/em><\/strong>about it are true\u00a0or false.<\/p>\n

Just a few years ago, nuclear proponents were pushing Generation 3\u00a0<\/em><\/strong>reactors — enormous plants that would generate huge amounts of\u00a0<\/em><\/strong>electricity, yet be cheaper and faster to build than earlier models,\u00a0<\/em><\/strong>as well as being safer and longer-lived.<\/p>\n

Then Areva ran into a blizzard of problems trying to build one of these behemoths in\u00a0<\/em><\/strong>Finland — the cost soaring by billions, the construction\u00a0<\/em><\/strong>time stretched by years, and fundamental safety-related design\u00a0<\/em><\/strong>problems surfacing late in the game. \u00a0Check and mate.<\/p>\n

Undaunted, nuclear proponents quickly executed a 180-degree turn\u00a0<\/em><\/strong>and are now promoting small reactors which can be mass-produced\u00a0<\/em><\/strong>by the thousands and sprinkled on the landscape like cinnamon on\u00a0<\/em><\/strong>toast. \u00a0Pebble-bed reactors, molten-salt reactors, thorium reactors,\u00a0<\/em><\/strong>have been paraded before the public with as many bells and whistles\u00a0<\/em><\/strong>as the nuclear industry can muster, to distract people’s gaze away from\u00a0the construction fiascos, the litany of broken promises from the past,\u00a0<\/em><\/strong>the still-unsolved problems of nuclear waste and nuclear weapons proliferation,\u00a0<\/em><\/strong>and the horror that is Fukushima.<\/p>\n

The following paragraphs are written to dispel some of the mystique\u00a0<\/em><\/strong>surrounding the idea of “thorium reactors” — a very old idea that is\u00a0<\/em><\/strong>now being dressed up in modern clothes and made to seem like a\u00a0<\/em><\/strong>major scientific breakthrough, which it is not.<\/p>\n

Thorium is not a nuclear fuel<\/em><\/strong><\/p>\n

The fundamental fact about thorium is that it is NOT a nuclear fuel, because thorium is not a fissile material, meaning that it cannot sustain a nuclear fission chain reaction.<\/p>\n

In fact\u00a0the ONLY naturally occurring fissile material is uranium-235,\u00a0 and so — of necessity —\u00a0that is the material that fuels all of the\u00a0 first-generation reactors\u00a0in the entire world. \u00a0Thorium cannot replace uranium-235 in this regard. \u00a0Not at all.<\/p>\n

Thorium is a “fertile” material<\/em><\/strong><\/p>\n

But thorium-232, which is a naturally occurring radioactive material, is about three times as abundant as uranium-238, which is also a naturally occurring radioactive material. \u00a0Neither of these materials\u00a0 can be used\u00a0directly as a nuclear fuel, because they are not “fissile”\u00a0 materials.<\/p>\n

However, both uranium-238 and thorium-232 are “fertile” materials, which means that IF they are placed in the core of a nuclear reactor (one that is of necessity fuelled by some other material — a fissile material), some fraction\u00a0 of those\u00a0fertile atoms will be transmuted into man-made fissile atoms.<\/p>\n

Inside a nuclear reactor, some uranium-238 atoms will get transmuted into plutonium-239 atoms,\u00a0 and\u00a0some thorium-232 atoms will get transmuted into uranium-233 atoms.<\/p>\n

Both plutonium-239 and uranium-233 are fissile materials which are not naturally-occurring. \u00a0They are both usable as either fuel for nuclear reactors or as nuclear explosive materials for bombs.<\/p>\n

In “Operation Teapot”, the USA exploded an atomic bomb made from uranium-233 in 1955.<\/p>\n

Reprocessing of irradiated nuclear fuel<\/em><\/strong><\/p>\n

In general, to obtain quantities of plutonium-239 or uranium-233, it has been necessary to “reprocess” the irradiated material that started out as uranium-238 or thorium-232. \u00a0This means dissolving that irradiated material in acid and then chemically separating out the fissile plutonium-239 or uranium-233, leaving behind the liquid radioactive wastes which include dozens of fission products (broken pieces of split atoms, including such things as iodine-131, cesium-137,\u00a0 strontium-90, etc.) and other radioactive waste materials called “activation products” and “transuranic elements”.<\/p>\n

Reprocessing is the dirtiest process in the entire nuclear fuel chain, because of the gaseous radioactive releases, liquid radioactive discharges, and large quantities of highly dangerous and easily dispersible radioactive liquids. Reprocessing also poses great proliferation risks because it produces man-made fissile materials\u00a0 which can be incorporated into nuclear weapons of various kinds by anyone who acquires the separated fissile material.<\/p>\n

Advanced Fuel Cycles and Breeders<\/em><\/strong><\/p>\n

Any nuclear reactor-fuelling regime that requires reprocessing, or\u00a0 that uses plutonium-239 or uranium-233 as a primary reactor fuel, is called an “advanced fuel cycle”. \u00a0These advanced fuel cycles are intimately related with the idea of a “breeder” reactor — one which creates as much or more fissile material as a byproduct than the amount of fissile material used to fuel the reactor. \u00a0So it is only in this context (the context of “breeders” or “near-breeders”) that thorium reactors make any sense at all — like all breeder concepts, they are intended to extend the fuel supply of nuclear reactors and thus prolong the nuclear age by centuries.<\/p>\n

The breeder concept is very attractive to those who envisage a virtually limitless future for nuclear reactors, because the naturally occurring uranium-235 supply is not going to outlast the oil supply. Without advanced fuel cycles, nuclear power is doomed to be just a “flash in the pan”. \u00a0Thorium reactors are most enthusiastically promoted by those who see “plutonium breeders” as the only other realistic alternative to bring about a long-lived nuclear future. They think that \u00a0\u00a0thorium-232\/uranium-233\u00a0<\/em>\u00a0 is a better fate than \u00a0\u00a0uranium-238\/plutonium-239\u00a0<\/em>. \u00a0They do not see a nuclear phaseout as even remotely feasible or attractive.<\/p>\n

There have been many incarnations of the thorium reactor concept over the last seventy years, some imaginary and some real. The latest version — the Liquid Molten Salt version — theoretically reduces the amount of reprocessing needed, although it does require reprocessing to get it started. This conceptual technology is being strongly promoted in the wake of the Fukushima disaster combined with the disappointing non-performance of the so-called “nuclear renaissance”. It is important to note that no one has built and operated such a reactor in a commercial context, or even as a pilot project.<\/p>\n

“Molten Salt” reactors<\/em><\/strong><\/p>\n

Molten salt reactors are not a new idea, and they do not in any way require the use of thorium — although historically the two concepts have often been linked. \u00a0The basic idea of using molten salt instead of water (light or heavy water) as a coolant\u00a0 has a number of distinct advantages,\u00a0chief of which is the ability\u00a0 to achieve much higher temperatures\u00a0(650 deg. C instead of\u00a0 300 deg. C) than with water-cooled reactors,\u00a0and at a much lower\u00a0 vapour pressure. \u00a0The higher temperature means\u00a0greater efficiency\u00a0 in converting the heat into electricity, and the lower\u00a0pressure means\u00a0 less likelihood of an over-pressure rupture of pipes,\u00a0and less drastic\u00a0 consequences of such ruptures if and when they do occur.<\/p>\n

Molten salt reactors were researched at Oak Ridge Tennessee throughout the 1960s, culminating in the Molten Salt Reactor Experiment (MSRE), producing 7.4 megawatts of heat but no electricity. It was an early prototype of a thorium breeder reactor, using uranium and plutonium as fuels but not deploying the “thorium blanket” which would have been used to “breed” uranium-233 to be recovered through reprocessing — the ultimate intention of the design.<\/p>\n

This Oak Ridge work was based on the assumption that two separate reprocessing plants would be required — one to extract plutonium and the other to extract uranium-233 from irradiated nuclear fuel. The work culminated in the period from 1970-76 in a design for a Molten Salt Breeder Reactor (MSBR) using thorium as a “fertile material” to breed “fissile” uranium-233, which would ultimately be extracted using a reprocessing facility.<\/p>\n

Molten Salt Thorium reactors without reprocessing?<\/em><\/strong><\/p>\n

Although it is theoretically possible to imagine a molten-salt reactor design where the thorium-produced uranium-233 is immediately used as a reactor fuel without any actual reprocessing, such reactor designs are very inefficient in the “breeding” capacity\u00a0 and therefore pose financial disincentives of a serious nature to any would-be developer. No one had actually built such a reactor or had aspirations to build one (until this year, when the Chinese government expressed its intentions to investigate the technology) because it just didn’t seem worth it compared with those designs which incorporate a reprocessing facility.<\/p>\n

Here’s what Wikipedia says\u00a0on this matter (it happens to be good info):<\/p>\n

http:\/\/en.wikipedia.org\/wiki\/Molten_salt_reactor<\/a><\/p>\n

To exploit the molten salt reactor’s breeding potential to the fullest, <\/em>the reactor must be co-located with a reprocessing facility. Nuclear\u00a0<\/em>reprocessing does not occur in the U.S. because no commercial\u00a0<\/em>provider is willing to undertake it. The regulatory risk and associated\u00a0<\/em>costs are very great because the regulatory regime has varied\u00a0<\/em>dramatically in different administrations.<\/em>\u00a0[20]<\/a><\/em>\u00a0\u00a0 UK, France, Japan,\u00a0<\/em>Russia and India currently operate some form of fuel reprocessing.<\/em><\/p>\n

Some U.S. Administration departments have feared that fuel reprocessing in any form could pave the way to the \u00a0<\/em>\u00a0plutonium economy<\/a>\u00a0\u00a0 with its associated proliferation dangers.<\/em>[21]<\/a><\/em><\/p>\n

A similar argument led to the shutdown of the \u00a0<\/em>Integral Fast Reactor<\/a><\/em>\u00a0<\/em>\u00a0\u00a0project in 1994.\u00a0<\/em>[22]<\/a><\/em>\u00a0\u00a0 The proliferation risk for a thorium fuel cycle stems from the potential separation of uranium-233, which might be used in nuclear weapons, though only with considerable difficulty.<\/em><\/p>\n

Currently the Japanese are working on a 100-200 MWe molten salt thorium breeder reactor, using technologies similar to those used at\u00a0 Oak Ridge, but the Japanese project seems to lack funding. India is pursuing thorium near-breeder technology of a more conventional kind with full reprocessing capabilities, dating back to\u00a0Canadian plans<\/a>\u00a0in the 1970s that never saw the light of day. (In fact, India has been trying to develop a thorium breeder fuel cycle for decades but has not yet done so commercially.)<\/p>\n

However, a few weeks before the tsunami struck Fukushima’s uranium reactors and shattered public faith in nuclear power, China revealed that it was launching a R&D program to develop a molten salt reactor design that would use liquid thorium-fluoride (ThF4) fuel as well, and that would not require reprocessing after the initial fuelling.<\/p>\n

But this is by no means an off-the-shelf technology. The optimism and zeal exhibited by its proponents is based not only on technological considerations, but is also driven by a sense of “nuclear fatalism” (that civilization cannot survive without nuclear energy) combined with a heady air of “engineering euphoria” that often accompanies such an attitude.<\/p>\n

Thorium reactors do not eliminate problems<\/em><\/strong><\/p>\n

The bottom line is this. \u00a0Thorium reactors still produce high-level\u00a0 radioactive waste. They still pose problems and opportunities for the proliferation of nuclear weapons. They still present opportunities for catastrophic accident scenarios — as potential targets of terrorist or military attack, for example.<\/p>\n

Proponents of thorium reactors argue that all of these risks are somewhat reduced in comparison with the conventional plutonium breeder concept.\u00a0\u00a0Whether this is true or not, the fundamental problems associated with nuclear power have by no means\u00a0been eliminated.<\/p>\n

Gordon Edwards, Ph.D., President,
\nCanadian Coalition for Nuclear Responsibility.<\/p>\n","protected":false},"excerpt":{"rendered":"

Thorium Reactors: Back to the Dream Factory by Gordon Edwards, July 13, 2011 \u00a0 The Nuclear Dream Factory Every time a nuclear power reactor idea doesn’t work out, and ordinary people get down-hearted and\u00a0start to doubt the magnificence and\u00a0benificence of nuclear energy,\u00a0nuclear proponents rush back to their well-stocked dream factory to fetch another idea — …<\/p>\n

Thorium Reactors: Back to the Dream Factory<\/span> Lire la suite\u00a0\u00bb<\/a><\/p>","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"disabled","ast-breadcrumbs-content":"","ast-featured-img":"disabled","footer-sml-layout":"","theme-transparent-header-meta":"default","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-1761","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/pages\/1761","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/comments?post=1761"}],"version-history":[{"count":1,"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/pages\/1761\/revisions"}],"predecessor-version":[{"id":1762,"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/pages\/1761\/revisions\/1762"}],"wp:attachment":[{"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/media?parent=1761"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/categories?post=1761"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wp.ccnr.org\/fr\/wp-json\/wp\/v2\/tags?post=1761"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}