Last month the US Energy Secretary, Jennifer Granholm announced a successful experiment at the Lawrence Livermore National Laboratory in which 192 lasers were used to pump 2.05 mega Joules of energy into a capsule heating its contents to 100 million degrees Centigrade causing fusion of hydrogen nuclei and the release of 3.15 mega Joules of energy. An apparent gain of 1.1 mega Joules until you take account of the 300 mega Joules consumed by the 192 lasers. The reaction in the media to this fusion energy experiment and the difficulties associated with building a practical fusion power plant, such as the Spherical Tokamak Energy Production (STEP) project in the UK (see ‘Celebrating engineering success‘ on November 11th, 2022) reminded me of a well-known memorandum penned by Admiral Rickover in 1953. Rickover was first tasked, as a Captain, to look at atomic power in May 1946 not long after first human-made self-sustaining nuclear chain reaction was initiated in Chicago Pile #1 during an experiment led by Enrico Fermi in 1942. He went on to become Admiral Rickover who directed the US Navy’s nuclear propulsion programme and the Nautilus, the first nuclear-powered submarine was launched in 1954. With thanks to a regular reader of this blog who sent me a copy of the memo and apologies to Admiral Rickover, here is his memorandum edited to apply to fusion energy:
Important decisions about the future of fusion energy must frequently be made by people who do not necessarily have an intimate knowledge of the technical aspects of fusion. These people are, nonetheless, interested in what a fusion power plant will do, how much it will cost, how long it will take to build and how long and how well it will operate. When they attempt to learn these things, they become aware the confusion existing in the field of fusion energy. There appears to be unresolved conflict on almost every issue that arises.
I believe that the confusion stems from a failure to distinguish between the academic and the practical. These apparent conflicts can usually be explained only when the various aspects of the issue are resolved into their academic and practical components. To aid in this resolution, it is possible to define in a general way those characteristics which distinguish one from the other.
An academic fusion reactor almost always has the following basic characteristics: (1) It is simple. (2) It is small. (3) It is cheap. (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose . (7) The reactor is in the study phase. It is not being built now. On the other hand, a practical fusion reactor can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is complicated.
The tools of the academic-reactor designer are a piece of paper and a pencil with an eraser. If a mistake is made, it can always be erased and changed. If a mistake is made, it can always be erased and changed. If the practical-reactor designer errs, they wear the mistake around their neck; it cannot be erased. Everyone can see it.
The academic-reactor designer is a dilettante. They have not had to assume any real responsibility in connection with their projects. They are free to luxuriate in elegant ideas, the practical shortcomings of which can be relegated to the category of ‘mere technical details’. The practical-reactor designer must live with these same technical details. Although recalcitrant and awkward, they must be solved and cannot be put off until tomorrow. Their solutions require people, time and money.
Unfortunately for those who must make far-reaching decisions without the benefit of an intimate knowledge of fusion technology and unfortunately for the interested public, it is much easier to get the academic side of an issue than the practical side. For the large part those involved with academic fusion reactors have more inclination and time to present their ideas in reports and orally to those who will listen. Since they are innocently unaware of the real and hidden difficulties of their plans, they speak with great facility and confidence. Those involved with practical fusion reactors, humbled by their experiences, speak less and worry more.
Yet it is incumbent on those in high places to make wise decisions, and it is reasonable and important that the public be correctly informed. It is consequently incumbent on all of us to state the facts as forth-rightly as possible. Although it is probably impossible to have fusion technology ideas labelled as ‘practical’ or ‘academic’ by the authors, it is worthwhile both authors and the audience to bear in mind this distinction and to be guided thereby.
Image: The target chamber of LLNL’s National Ignition Facility, where 192 laser beams delivered more than 2 million joules of ultraviolet energy to a tiny fuel pellet to create fusion ignition on Dec. 5, 2022 from https://www.llnl.gov/news/national-ignition-facility-achieves-fusion-ignition
The chatbot, ChatGPT developed by OpenAI, has been in the news recently and is the subject of much discussion in universities primarily because of its potential use by students to complete their coursework assignments but also the positive uses to which it might be applied. After last week’s invitations to edit two special issues in different journals on cosmetic dentistry and wire arc additive manufacturing (WAAM) [‘Wire arc additive manufacturing and cosmetic dentistry?‘ on February 8th, 2023], I did a little research in the scientific literature to find out if anyone had published research on using WAAM to make parts for cosmetic dentistry but found nothing. I was not surprised – the level of precision achievable with WAAM is about 1 millimetre which would be insufficient for most applications in cosmetic dentistry. Then, I signed up for a free trial with ChatGPT and conducted an experiment by asking it to write about wire arc additive manufacturing and cosmetic dentistry. The chatbot produced 128 words about how WAAM is becoming increasing popular in cosmetic dentistry because of its accuracy and precision also because a wide range of materials can be used allowing a match to the colour and texture of teeth. I repeated the experiment and the chatbot produced 142 different words, again stating that dental prostheses can be produced using WAAM with high precision and accuracy to match a patient’s existing teeth in colour so that restorations appear natural and undetectable. In each case the six or seven sentences were well-written and included some facts that were used to construct a set of false statements, which superficially appeared reasonable; however, only a modicum of knowledge would be required to identify the fallacious rationale. Some of my colleagues are already exploring incorporating the chatbot into students’ coursework by asking students to use it to generate a description of a technical topic and then asking them to critique its output in order to assess their understanding of the topic. I expect chatbots will improve rapidly but for the moment it is relatively easy to induce them to write nonsense.
Realize Engineering 
