{"id":4971,"date":"2016-10-17T17:40:56","date_gmt":"2016-10-17T22:40:56","guid":{"rendered":"http:\/\/helian.net\/blog\/?p=4971"},"modified":"2016-10-17T17:40:56","modified_gmt":"2016-10-17T22:40:56","slug":"nuclear-fusion-update-2","status":"publish","type":"post","link":"https:\/\/helian.net\/blog\/2016\/10\/17\/nuclear-weapons\/nuclear-fusion-update-2\/","title":{"rendered":"Nuclear Fusion Update"},"content":{"rendered":"

At the moment the National Ignition Facility<\/a> (NIF) at Lawrence Livermore National Laboratory is in a class by itself when it comes to inertial confinement fusion (ICF) facilities.\u00a0 That may change before too long.\u00a0 A paper by a group of Chinese authors describing a novel 3-axis cylindrical hohlraum design <\/a>recently appeared in the prestigious journal Nature<\/em>.\u00a0 In ICF jargon, a “hohlraum” is\u00a0a container, typically cylindrical in form.\u00a0 Powerful laser beams are aimed through two or more entrance holes\u00a0to illuminate\u00a0the inner wall of the\u00a0hohlraum, producing a burst of x-rays.\u00a0 These strike a target mounted inside the hohlraum containing fusion fuel, typically consisting of heavy isotopes of hydrogen, causing it to implode.\u00a0 At maximum compression, a series of shocks driven into the target are supposed to converge in the center, heating a small “hot spot” to fusion conditions.\u00a0 Unfortunately, such “indirect drive” experiments haven’t worked so far on the NIF.\u00a0 The 1.8 megajoules delivered by NIF’s 192 laser beams haven’t been enough to achieve fusion with current target designs, even though the beams are very clean and uniform, and the facility itself is working as designed.\u00a0 Perhaps the most interesting thing about the Chinese paper is not their novel three axis hohlraum design, but the fact that they are still interested in ICF at all in spite of the failure of the NIF to achieve ignition to date.\u00a0 To the best of my knowledge, they are still planning to build SG-IV, a 1.5 megajoule facility<\/a>, with ignition experiments slated for the early 2020’s.<\/p>\n

Why would the Chinese want to continue building a 1.5 megajoule facility in spite of the fact that U.S. scientists have failed to achieve ignition with the 1.8 megajoule NIF?\u00a0 For the answer, one need only look at who paid for the NIF, and why.\u00a0 The project was paid for by the people at the Department of Energy (DOE) responsible for maintaining the nuclear stockpile.\u00a0 Many of our weapons designers were ambivalent about the value of achieving ignition before the facility was built, and were more interested in the facility’s ability to access physical conditions relevant to those in exploding nuclear weapons for studying key aspects of nuclear weapon physics such as equation of state (EOS) and opacity of materials under extreme conditions.\u00a0 I suspect that’s why the Chinese are pressing ahead as well.\u00a0 Meanwhile, the Russians have also announced a super-laser project <\/a>of their own that they claim will deliver energies of 2.8 megajoules.<\/p>\n

Meanwhile, in the wake of the failed indirect drive experiments on the NIF, scientists in favor of the direct drive approach have been pleading their case.\u00a0 In direct drive experiments the laser beams are shot directly at the fusion target instead of at the inner walls of a hohlraum.\u00a0 The default approach for the NIF has always been indirect drive, but the alternative approach may be possible using an approach called “polar direct drive<\/a>.”\u00a0 In recent experiments at the OMEGA laser facility at the University of Rochester’s Laboratory for Laser Energetics, the nation’s premier direct drive facility, scientists claim to have achieved results that, if scaled up to energies available on the NIF would produce five times more fusion energy <\/a>output than has been achieved with indirect drive to date.<\/p>\n

Meanwhile, construction continues on ITER<\/a>, a fusion facility designed purely for energy applications.\u00a0 ITER will rely on magnetic plasma confinement, the other “mainstream” approach to harnessing fusion energy.\u00a0 The project is a white elephant that continues to devour ever increasing amounts of scarce scientific funding in spite of the fact that the chances that magnetic fusion will ever be a viable source of electric power are virtually nil.\u00a0 That fact should be obvious by now, and yet the project staggers forward, seemingly with a life of its own.\u00a0 Watching its progress is something like watching the Titanic’s progress towards the iceberg.\u00a0 Within the last decade the projected cost of ITER has metastasized from the original 6 billion euros to 15 billion euros in 2010, and finally to the latest estimate of 20 billion euros.\u00a0 There are no plans to even fuel the facility for full power fusion until 2035<\/a>!\u00a0 It boggles the mind.<\/p>\n

Magnetic fusion of the type envisioned for ITER will never come close to being an economically competitive source of power.\u00a0 It\u00a0would already be a stretch\u00a0if it were\u00a0merely a question of\u00a0controlling an unruly plasma and figuring out\u00a0a viable way to\u00a0extract the fusion energy.\u00a0 Unfortunately, there’s another problem.\u00a0 Remember all those yarns you’ve been told about how an unlimited supply of fuel is supposed to be on hand in the form of sea water?\u00a0 In fact, reactors like ITER won’t work without a heavy isotope of hydrogen known as tritium.\u00a0 A tritium nucleus contains a proton and two neutrons, and, for all practical purposes,\u00a0the isotope doesn’t occur in nature, in sea water or anywhere else.\u00a0 It is highly radioactive, with a very short half-life of a bit over 12 years, and the only way to get it is to breed it.\u00a0 We are told that fast neutrons from the fusion reactions will breed sufficient tritium in lithium blankets surrounding the reaction chamber.\u00a0 That may work on paper, but breeding enough of the isotope and then somehow extracting it will be an engineering nightmare.\u00a0 There is virtually no chance that such reactors will ever be economically competitive with renewable power sources combined with baseline power supplied by proven fission breeder reactor technologies.\u00a0 Such reactors can\u00a0consume most of the long-lived\u00a0transuranic waste they produce.<\/p>\n

In short, ITER should be stopped dead in its tracks and abandoned.\u00a0 It won’t be, because too many reputations and too much money\u00a0are on the line.\u00a0 It’s too bad.\u00a0 Scientific projects that are far worthier of funding will go begging as a result.\u00a0 At best my descendants will be able to say, “See, my grandpa told you so!”<\/p>\n

\n\t\t\t\t\tTweet<\/a>\n\t\t\t\t<\/div><\/div>","protected":false},"excerpt":{"rendered":"

At the moment the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is in a class by itself when it comes to inertial confinement fusion (ICF) facilities.\u00a0 That may change before too long.\u00a0 A paper by a group of Chinese authors describing a novel 3-axis cylindrical hohlraum design recently appeared in the prestigious journal … Continue reading “Nuclear Fusion Update”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[61,43,78,22,246,23,10],"tags":[121,342],"class_list":["post-4971","post","type-post","status-publish","format-standard","hentry","category-china","category-environment","category-fusion-energy","category-inertial-confinement-fusion","category-national-ignition-facility-2","category-nuclear-energy","category-nuclear-weapons","tag-fusion-energy-2","tag-magnetic-fusion"],"jetpack_publicize_connections":[],"jetpack_shortlink":"https:\/\/wp.me\/pwEq0-1ib","jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/posts\/4971","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/comments?post=4971"}],"version-history":[{"count":3,"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/posts\/4971\/revisions"}],"predecessor-version":[{"id":4974,"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/posts\/4971\/revisions\/4974"}],"wp:attachment":[{"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/media?parent=4971"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/categories?post=4971"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/helian.net\/blog\/wp-json\/wp\/v2\/tags?post=4971"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}