My thinking was catalyzed by a chorus of recent news releases and internet postings heralding the "new discovery" by someone that molten salt reactors (MSRs) can transform the world by providing cheap electricity, utilizing thorium, burning plutonium, and destroying actinides and radioactive waste. Without addressing the technical validity of these assertions, let me say I find this "discovery" or more accurately "re-discovery" phenomenon fascinating from the standpoint of knowledge retention and inter-generational knowledge transfer (or lack thereof). I wonder how many times through the ages fire has been "discovered"?
One of the reasons the molten salt reactor example is so interesting is that virtually all of the asserted benefits of of molten salt reactors were originally cited in the mid-to-late-1950's (when I was a toddler...) In fact, Briant and Weinberg asserted most of the benefits (including the ability to run on uranium, thorium, and plutonium fuel cycles) in their 1957 paper in Nuclear Engineering and Design. Subsequently, these attributes have been explored on a cyclical basis by a variety of domestic and international entities and collaborations, with the last real flurry of interest in the MSR coming a decade or more ago when there was renewed interest in the potential use of MSRs for radioactive waste transmutation. But enough about MSRs. They are simply the example that triggered this stream of consciousness.
Now back to knowledge retention and transfer...
Throughout my 30+ years in the energy R&D field, I've observed that the "dusting-off" of, or "re-look" at "old technologies" and technical approaches is generally wise whenever one or more of Three Criteria are met:
(1) A scientific & technical discovery has been made (such as the understanding of a fundamental phenomenon) that provides a critical insight previously unknown;
(2) Changes and evolution in base or enabling technology (such as a new material) enables one to do things not previously possible;
(3) Externalities (such as constraints, perceived need & urgency, societal / cultural values, changes in competing technology acceptability, etc.) shift or change in a manner that potentially improves the perceived risk/reward math for the "old technology".
Put differently, "old technologies" tend to be (or perhaps should be) revisited when their: (1) technical feasibility, (2) economic viability, or (3) environmental acceptability RELATIVE TO COMPETING TECHNOLOGIES change.
Just as the biosphere is a preserve or "library" of "solutions to problems" (perhaps to problems or challenges we don't even know we face), our knowledge base of "old technologies" is a library of potential solutions to problems (current and future). But what happens when the "library" is lost? (After all, who knows what was lost when the Library of Alexandria burned?)
I can't help but recall a situation at ORNL some twenty years ago when I inherited the last remaining "gold files" (three file cabinets) of Art (Arthur P.) Fraas an internationally known energy technology engineer who retired from Oak Ridge in 1976 and passed away in 2011 at the ripe old age of 95. Art was an engineer's engineer – a remarkably gifted and versatile individual. Among other things, he was known in the 1950s-1970s as one of the most innovative engineers at work in the development of both advanced terrestrial and space power reactor concepts. When Art retired in 1976, he transferred what he considered to be his most important personal files, notes, and log books to another engineer, who, in turn, left them in the safe keeping of "management" when he retired. Some time afterwards I was made aware of the files and was asked if I wished to preserve them. Having been told these were "Art's files", I rushed down to the basement of the old Y-12 calutron building where they were being stored (one of the buildings where the uranium for the "Little Boy" atomic bomb of World War II was enriched). With great anticipation I approached the first file cabinet and opened the drawer. It was empty. I open a second drawer. Nothing but dust. A third drawer creaked as I pulled it open and surprised some cockroaches. And so on with the other two cabinets. It turns out that, with the exception of two binders of old photographs, all of Arts files had been tossed out about a week earlier in an effort to clear the area of "debris and refuse". I can't tell you how many times over the past twenty years I wondered what was lost. I could relate other similar stories. I guess someday someone with "discover" what we tossed out - or not.
We live in a "throw away" society. And the good news? History teaches us that, given enough time, mankind tends to "rediscover" that which has been lost – or at least fragments of what has been lost. The internet is making it possible to preserve more and more of our society's knowledge legacy. But rather than simply stumbling upon a rediscovery, wouldn't it be wonderful if our "search" capabilities enabled us to stitch together knowledge bases, filtered through the Three Criteria I cited above, to provide society a deliberate and structured approach to re-examining or "mining" historical knowledge and technology bases? Now that would be a "search engine" for the ages!