b'P ROVING THE P RINCIPLEthe event produced no sound, no steam, Argonne s Idaho team extracted the core continued to serve for experiments. In no smoke, no explosion. Zinn reported from the reactor, built a shielded coffi n1962 Argonne installed what would bethe incident to the AEC the next day. for it, and shipped it to Chicago. ThEBR-Is last core, this one with plutoni-eZinn the scientist absorbed what there analysts found that in the extraordinary um fuel. Experiments continued untilwas to learn and saw an opportunity heat, the fuel elements had bowed and Argonne shut down the reactor in 1964,perhaps making lemonade out of a expanded, bringing too many uranium ready to move on with EBR-II, the nextlemonto learn how to handle a dam- atoms too close to one another. The heat evolutionary step in the march towardaged core safely and efficiently. 23 had been greater on one side of the ele- commercial-sized fast breeders. 26ments than the other, and since the fuelThe episode, while being the first unin- was clamped at both ends, it bent toward To further understand the behavior oftended meltdown in American nuclear the higher heat, a simple mechanical fast neutrons during an excursionandhi sor y, possibly would have acquired the event. In the future, this could be easily while fuel was meltingArgonne builtt patina of one of those things that hap- pr e d. 2 5 TREAT, the Transient Reactor Testv ent epens in the course of Facility, transiente x pe r imen a i being a term similar t to n ,except that AEto excursion, indi-CHeadquarters decided cating very tempo-not to inform the rary bursts ofpublic. The news power. The reactorleaked out in Apr i l would test candidate 1956, covered by the fuels for EBR-II asnuclear and national well. Because thepresses. The editor of transient tempera-N u c l e o n i c sw a rnetures would be dthe AEC that nuclear extremely high,accidents were public TREATs specialbusiness. In words fuel was made bythat would later seem embedding and bak-prophetic, he said, ing highly enrichedApart from the bad uranium in graphite.ef fect that secrecy When the tempera-would have on atti- ture of fast-movingtudes toward nuclear INEEL 69-4254 neutrons was made s af e t y, such with- to spike, theholding of news is wrong in principle. It Operator demonstrates insertion of fuel element in graphite acted as a heat sink, protectingis beyond the authority of AEC to with- ZPPR (Zero Power Physics Reactor), housed at the fuel. Slots through the core provid-hold information not affecting the nation- Argonne-West. Physicists could mock up various ed an opening for a camera to recordal security. And because AEC operates in arrangements of fuel and control elements and test the events taking place in the test holeso much secrecy, public confidence in it them at low power. The reactor was made critical by during the excursion. 27will surely be undermined. 24moving one half of the reactor closer to the other.TREATs early experiments deliberate-Lost to public notice was the discovery ly melted fuel elements and assembliesof how the meltdown had occurred and EBR-I received a new core in 1957 to learn more about how fast-reactorwhy higher heat in the reactor had pro- employing zirconium spacers and other cores would behave during a meltdown.duced a positive temperature coeff ic i ent.features to hold the fuel rigid. EBR-I As testing progressed, Argonne evolved 13 6'