#BOFN: “Safety”

Richard Hull runs his fusor at safe levels on the order of 10^ n/s.  Much beyond that requires additional shielding and/or distance from the reactor.
Richard Hull runs his fusor at safe levels on the order of 10^ n/s. Much beyond that requires additional shielding and/or distance from the reactor.

If you’ve read anything about the promise of nuclear fusion, one of the words you encounter most frequently is “safe.” As in nuclear fusion will one day be a “clean, safe, and inexhaustible…” source of nuclear energy.

Yeah, well, maybe.  Relatively speaking.

Compared to the nuclear reactors online today, yes, fusion is probably “safer” than fission.

For starters, you don’t have all the fuel present in the reactor the entire time – as you do with a fission reactor – so there is no danger of coolant breakdown, overheating and meltdown. (I’m tempted to draw this analogy: a fission reactor is a bit like putting your automobile engine inside the gas tank.  What could possibly go wrong?)

To the contrary, all fusion experiments to date have involved vacuum chambers – the object is to have next-to-nothing in the chamber itself, and then admit only as much nuclear fuel as it takes to generate or sustain a reaction.  (Following the automobile engine analogy a little further, a fusion reactor would be more like the cylinder, where only a tiny amount of explosive fuel vapor is admitted to the chamber to ignite the combustion that makes the whole thing go ’round).  With a fusion reactor, the worst that could likely happen in the event of an accident is that the reaction chamber would rupture, the vacuum is lost, the reaction ceases, and a tiny bit of gas is released into the atmosphere. Not really much of a problem when measured against the “China Syndrome” scale of a potential fission reactor accident (see Fukushima, Chernobyl, Three Mile Island).

But let’s not kids ourselves that nuclear fusion is entirely “safe.”

First, we are still dealing with all the forces that bind atomic nuclei, and the radiation and particles that are released when atoms are split or combined.

Indeed, the whole way we measure fusion – by the quantity of neutrons produced – ventures into a realm that is potentially entirely lethal.  In most of the experimental installations that are discussed here at Fusor.net, the level of neutron output is sufficiently low that there is no danger to being in the vicinity of the reactor for relatively short periods.  But getting anywhere close to a self-sustaining reaction produces a neutron flux many orders of magnitude – i.e. in the trillions or even quadrillions – of neutrons per second.  And as Doug Coulter’s recent experience demonstrates, “safe” is not one of the words that would describe that level of output.

In addition to the neutron flux, there are the X-rays and the gamma rays that have to be shielded.

And then of course there are the extremely high voltages – i.e. tens of thousands of volts – that operate a fusor.  Be very careful what you touch…

So before plunging into one of these projects, it can be worth your time and effort to explore the forums for the myriad safety considerations that must be taken into account before building and operating your very own nuclear fusion reactor.

A simple search reveals that to date there are more than TWELVE HUNDRED posts that invoke the word “safety.”  What is interesting is that, near as I can tell, there is no “FAQ” set that specifically addresses the safety considerations that should be taken in to account when building and operating one of these things.

Perhaps a few advanced searches can narrow the subject down:

There are 400+ posts that address “voltage” safety;

There are 170+ posts that address “neutrons” safety;

There  are 150+ posts that address “X-rays” safety;

There are 280+ posts that address “vacuum” safety.

So, please, new users especially, avail yourselves to some of this material before embarking on a project with the blanket, unexamined assumption that nuclear fusion is perfectly “safe.” You’ll be glad you did…



#BOFN: “Pontiac”

The first Farnsworth Fusion team

It turns out that over the years, the Fusor.net forums have accumulated quite a bit of material that revisits the events that transpired at the ITT/Farnsworth laboratory in Fort Wayne, Indiana during the years when the Fusor was first introduced and developed (ca. 1959-1967).

That lab was located on Pontiac Street in Fort Wayne, so a search of the forums using just the word “Pontiac” delivers 40 results.  Almost (?) all of these posts start with something Richard Hull shares from the investigations and interviews he conducted with the Farnsworth fusion team back in the early ‘aughts.  I accompanied Richard on one of those expeditions in 2001 – the most pertinent results of those interviews (from my perspective, anyway) were included in my Farnsworth bio, The Boy Who Invented Television.

The full search results can be found here, and here are a few of the more choice threads:

 That’s just a sample of what can be found by running a search for ‘Pontiac’ in the forums.  If you’re relatively new here, it’s worth taking some time to drill through the links and hear some stories… it will give you a much better sense of the trail we are trying to follow, the footsteps we are trying to fill, and the legend that we’re trying to make sense of.

New Feature: The Best of Fusor.Net
#BOFN – Runaway! (Or… Not?)


When we discussed the future of Fusor.net at the HEAS gathering at Richard Hull’s home back in October, one of the recurring themes was: there is a wealth of information buried beneath the detritus of daily exchanges that one typically finds in the forums.

This site has been in existence more or less for nearly 20 years. The first iteration – the “songs.com” bbs – was so long ago – before the dreaded Y2K – that the posts don’t show the year.  But I’m pretty sure it was 1998.

Since then, knowledgeable people of all stripes have come and gone – or come and stayed – and deposited here a veritable treasure trove of information about the design, construction, and operation of the Farnsworth Fusor (or, more precisely, “Hirsch/Meeks Variation” of the Farnsworth Fusor).

So it is no wonder that much of the valuable information stored here can be found in posts that date back a decade or more.  The challenge now is to effectively mine those resources so the most valuable nuggets can be brought to the surface for the benefit of newcomers and veterans alike.

After exchanging some recent messages with Site Admin (and fusion veteran) Frank Sanns, I think we’ve come up with one way to periodically drill down and see what lies beneath.

Starting now, and hopefully once or twice a week for the foreseeable future, we’re going to post a series of “The Best of Fusor.Net.”

The key to the idea is the search engine that lives at the top of every page of the forums.  You can find out just about anything that’s ever been posted that way.  For example, search for “Gene Meeks”  (co-inventor of the fusor we build here) and you’ll find 60 entries over 10 pages that go back as far as 2001 – 14 years!

So clearly, there’s a ton of valuable stuff lying beneath the surface of this site. Let’s see what we can do to bring some of it closer to the surface.

– – – – – – – –

The "Mark 2 / Mod 2" fusor, one of the models that was operated in "the pit" in Fort Wayne. Photo from a scrapbook kept by Steve Blaising.
The “Mark 2 / Mod 2” fusor, one of the models that was operated in “the pit” in Fort Wayne. Photo from a scrapbook kept by Steve Blaising.

For the first entry in the “Best of…” sweepstakes, we visit the subject of “runaway fusors.”

Last week, Frank and I got in to an e-mail exchange about the “runaway fusion” events that have been reported to have occurred in the Farnsworth fusion laboratories in Fort Wayne, Indiana in the mid 1960s.   I think he was referring to an event that I described on page 232 of my Farnsworth bio, “The Boy Who Invented Television”

…. engineer Fred Haak described an occasion when he, George Bain, and an- other engineer named Jack Fisher were preparing the Fusor for a metered run that would be conducted the next day. There was no instrumentation on the Fusor during the setup. As was often the practice, the workers were putting the Fusor through its paces to make sure its systems were all functioning when, according to Fred Haak, the Fusor in the pit “just lit up and went crazy.” George Bain killed the power immediately but the Fusor did not shut down—it actually continued operating, as an increasingly bright light emanated from the pit. After this spontaneous operation had continued for at least 30 seconds—perhaps a minute—a “pop and a hiss” indicated that the stainless steel reactor vessel had been breached, releasing its vacuum, at which point the reaction finally ceased and the Fusor cooled down.

It’s Frank’s contention that such an event could not have happened, and to make his case he sent me a link to a thread entitled “Can A Fusor Explode?”

The thread was prompted by a question that Steve Sesselman – another Fusor.net veteran (who, incidentally, pretty much holds down the Aussie contingent of the community) posted back in 2005 – more than ten years ago.   What follows is an interesting discussion of some of the inner workings of the fusor, and possibly the belying of some of the legends that surround the Farnsworth labs in the 60s.

See for yourself,  it’s just a couple of pages of posts, and it’s just a sample of some of the material that would go unseen if we don’t make an effort to pull it out.

So “watch this space” (actually, this category) for more such posts in the weeks ahead.