This week, we talk High Temperature Gas Reactors, or HTGRs, with a Decouple favorite: reactor designer and nuclear historian Nick Touran. From the first conceptual sketch of an HTGR in wartime labs to today’s revival by players like X-energy and China’s fast-moving reactor fleet, we dissect what makes HTGRs unique—both in engineering promise and the difficulties that have long haunted their success. With helium cooling, TRISO fuel, and ambitions beyond electricity into process heat and industrial decarbonization, HTGRs may be poised for a comeback. But will history repeat itself, or finally break the cycle?
Enjoy longer shownotes, transcripts, and more on Substack: https://www.decouple.media
Episode title on podcast platforms: Hard Lessons with Hot Helium
Follow Nick Touran @whatisnuclear :
• What Is Nuclear: https://whatisnuclear.com/about.html
• X: https://x.com/whatisnuclear
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Website: https://www.decouple.media
Chapters:
00:00 Introduction
02:31 HTGR Basics
06:21 Low-temperature Gas Reactors
07:53 Farrington Daniels' brainchild
13:54 Why HTGRs are interesting
24:57 HTGRs in history
35:44 Technical challenges
43:33 The importance of just building
45:26 German HTGRs
51:28 Chinese HTGRs
55:24 Reactor lifespans
58:03 Process heat
1:07:09 Fuel challenges
1:10:08 The future of HTGRs: China v. the West