Broadcast 3018 Dr. Robert Hargraves

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Guest:  Dr. Robert Hargraves;  Topics:  Thorium as an energy source, thorium economics, nuclear issues and regulations, radiation, and much more.  Please direct all comments and questions regarding specific Space Show programs & guest(s) to the Space Show blog which is part of archived program on our website,  Comments and questions should be relevant to the specific Space Show program. Written Transcripts of Space Show programs are a violation of our copyright and are not permitted without prior written consent, even if for your own use. We do not permit the commercial use of Space Show programs or any part thereof, nor do we permit editing, YouTube clips, or clips placed on other private channels & websites. Space Show programs can be quoted, but the quote must be cited or referenced using the proper citation format. Contact The Space Show for further information. In addition, please remember that your Amazon purchases can help support The Space Show/OGLF. See

We welcomed Dr. Robert Hargraves to the program to discuss thorium energy, thorium reactors, and the economics of thorium.  We started our two segment 91 minute discussion b asking Dr. Hargraves to provide us with the basics of thorium, especially as compared to U-235 and U-233.  Dr. Hargraves did a great job of comparing thorium to the uranium isotopes, plus letting us know what happens to thorium when used and the conversion process to U-233.  This initial discussion was important as it served as a good foundation for moving forward with the program.   

Thorium economics were discussed in detail and as you will hear are a significant reason why we are not developing thorium reactors.  In fact, thorium reactors and demo plants are only pending in some third world countries due to the economics, cost, and availability of conventional nuclear fuels, plus the existence of a less burdensome regulatory environment.  As part of this discussion, I asked our guest about common statements made by callers and guests on TSS re thorium.  One such common statement I put to our guest was that federal law prohibited the use of thorium.  Another was that the supply of thorium was mostly in China so we did not want to import it.  The third common statement I put to our guest was that since thorium could not be used in weapons, there was less demand for it.  Dr. Hargraves threw cold water on all of these "rumors" but don't miss all of what he had to say about thorium economics, demo plans, weapons, supplies and their location, plus much more. 

Bob switched to talking about nuclear power plant design, pressure water reactors, and eventually the capital investment required for a plant.  I also asked him to define and explain the molten salt reactor.  In addition, Bob talked about thorium hybrids such as the one his company is working on, ThorCon.  Our guest elaborated on much of this so be sure to listen carefully as we talk nuclear plan technical details plus the same for a thorium plant and molten salt reactor. 

The final topic of the first segment was the nuclear and radiation fear culture we live in. We have talked about this before regarding nuclear propulsion but it came up again with thorium and nuclear power in general.  Listen to the examples provided by Bob. I also asked why France seemed to have a better nuclear culture and less fear than the US.  Also as part of this discussion, our guest suggested that our fear of radiation harm to humans was overstated.  This was controversial to many listeners and I am sure others who tend to dismiss radiation risks going to Mars for example, will jump for joy.  Listen carefully to what our guest said.  The subject came up in the second segment as well and the last question of the day was a very sarcastic one by Adrian going after our guest on this very topic.

We started Part 2 with a propulsion question from BJohn.  Our guest said space propulsion was not his field of expertise but he did not think thorium would be a benefit for spaceflight as other fuels would burn hotter and have more ISP.  Bob then talked about a lunar thorium plant which was discussed a long time ago.  He then talked about his ThorCon hybrid idea for Indonesia as a prototype plant.  Listen to why Indonesia was selected.  He also talked about making the plant components in a conventional shipyard.  He had much to say about manufacturing and how it would hold down the cost of the thorium prototype hybrid plant so don't miss this discussion. 

Adrian sent in his first note asking about gravity which was needed for the conversion.  I read Adrian's email in full so you can hear it.  Our guest responded to the issues Arian raised and agreed with him about the need for gravity.  A listener asked him specifically where there were thorium deposits in the US.  Our guest referenced New Hampshire and Missouri but said thorium was plentiful in the country. 

Listener June sent in a note asking about thorium user guidelines and rules and regulations.  This opened up a discussion about not just thorium regulation but nuclear industry regulation.  We talked about Congress, policy makers, educational outreach on the issue, China and much more.  Bob then talked about the lower Indonesian regulatory burden as a cost in terms of GDP.  Bob suggested again that radiation was not as bad as many believed and this promoted the sarcastic final question from Adrian that I referenced earlier in this summary.

Please post your comments/questions for Dr. Hargraves on TSS blog. You can reach our guest through me or through ThorCon at  Additionally, you can see a video about the ThorCon hybrid power plant for Indonesia (note his email contact is on the video) at




Thorium, everything you want to know about it, reactors & more

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17 Nov 2017 Robert Hargraves
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