A Brief History of: The Fermi 1 Reactor Meltdown (Short Documentary)

take you to my patreon for voting on this subject liquid sodium reactors have a sordid history as many have experienced some kind of incident a partial meltdown in Michigan would fuel the fire for the anti-nuclear movement however unlike many nuclear events the dangers to the public were negligible [Music] this is the second video in a row that involves a partial fuel meltdown and as a fascinating footnotes for reactor design but never really took off in mainstream commercial power generation today we are looking at the 1966 31 fast breeder reactor meltdown this isn't the first time I've covered an incident involving a sodium-cooled fast reactor and it probably won't be the last I'm looking at you EBR won the enrico fermi nuclear power plant is a generating station in New Port Berlin Charter Township Monroe County Michigan which is about here on a map the site is named after Nobel laureate Enrico Fermi and began construction on an experimental reactor in 1956 the site would get a second reactor with construction beginning in 1972 and being commissioned in 1988 Fermi too was a boiling water type reactor and a third identical reactor was planned but canceled in 1974 interesting too the commercial use of a fast breeder reactor has led many organizations down the path of building and experimental units and Fermi one was no different the allure of a fast breeder reactor is that the use of liquid metals such as sodium does not act as a moderator like water does the reactor type uses highly enriched fuel and can sustain a chain reaction with fast neutrons this type of reactor can create more fuel when it consumes meaning it could in theory sell fuel shortage issues this is done by using a fertile blanket of non fissile material such as depleted uranium however these types of reactors have two main disadvantages firstly is cost rendering the type not ideal for commercial applications and a second is the type of coolant liquid metal which can become volatile when exposed to the moisture in air meaning the event of a coolant leak could be deadly now that is a really really rough and brief overview of fast-breeder reactors let's look at the fermi one in particular the reactor received is sodium coolant in 1960 and achieved criticality in 1963 the reactor was tested at low power in its first couple of years of operation power testing above 1 megawatt commenced in December 1965 immediately after the receipt of its high power operating license the reactor had two calling loops both using liquid sodium the first loop passed fruity reactor core and went through a heat exchanger with the secondary loop flowing through it the heat transferred into the secondary loop and then went for a steam generator for use with a turbine for electrical power generation the coolant float upward from a high pressure plenum connected to the discharge lines of free primary sodium pumps the sodium flows upwards through the individual core and blanket sub assemblies into the large upper plenum then flows by gravity to the intermediate heat exchanges and then to the suction side of the primary pumps the plant was designed with a 430 megawatt capacity however the maximum reactor power with its first to call loading core a was 200 megawatts the reactor was capable of creating 69 megawatts of electrical power the reactor was contained in a stainless steel vessel sealed at the top by rotating shield plug the core was surrounded by a blanket of depleted uranium the total diameter of both core and blanket was 80 inches and had a height of 70 inches the core of the reactor consisted of a cylinder of 31 inches across with a depth of 31 inches this was made up of the control rods neutron source and multiple fuel sub assemblies of which were two point six inches square by eight feet tall each sub assembly had 140 pins of 25.6 enriched u-235 resulting in a total mass of 4.75 kilograms of uranium-235 per sub assembly the blanket used slugs of depleted uranium bonded in stainless steel tubes the reactor was designed to be controlled by only two control rods how provisions for eight others as safety rods were built into the design of the unit at the time the meltdown only seven had been installed how the reactor had been successfully operated with as few as six safety rods to normal operations roads were held out of the reactor core ready to be used in the event of a scram after the two main controls only one was used for major regulating of the reactors power will he ever being used for shimming are you fine-tuning all the rods were of a Poisson type design employing enriched boron 10 right miss leads us up to October 1966 in the nine months prior a total of approximately 717 megawatts of reactor operation was logged these operations include a 60 hour test at a hundred megawatts junus extended test some temperature abnormalities were recorded however these were within design spec a test was planned for the 4th and 5th of October it was intended to measure temperatures at the reactor vessel transfer a rotor in a number one steam generator and a sub assembly sodium outlets check new pressure control adjustment on the main steam bypass line and adjust the automatic feed water flow control system when a 4th October the reactor was gradually started up to 1 megawatts to heat up the coolant to just under 518 degrees Fahrenheit a 14-1 the steam generation valves delayed the upping of the reactor output to 145 p.m. on the 5th at 2 p.m. the reactor was operating at 5 megawatts an issue of a boiler feedwater pump meant that the reactor power was reduced to 2 megawatts for 20 minutes once the issue was sorted the power rose to 8 megawatts director was input on automatic control until about 3:00 p.m. reaching a pair of 20 megawatts director operators observe variations in the automatic control system this problem had been experienced in the past about the same power level and was fought to be interference picked up by the control system the operators place the reactor under manual control as had happened before the interference ceased and the reactor was put back into automatic control but a power rise to continue just after 3 p.m. a staff member in charge of the operation saw that the control rods appear to be withdrawn further than normal for this power level both the Shem and regulating rods were approximately 9 inches withdrawn usually at this time the rods would be at around 6 inches abnormally high sodium outlet temperatures were being indicated over two sub assemblies at this time the power output was at 31 megawatts at 3:09 p.m. radiation alarms in the upper to building ventilation system duct alerted the operators elevated radiation was recorded in the following areas the six-inch exhaust line from the upper reactor building the free inch exhaust line from the machinery dome up a reactor building and machinery dome exhaust the waste gas building valve room and deficient product detector building the power to reactor was quickly reduced to three point three megawatts as operators scrander unit the containment building was automatically isolated although there was no one inside at the time a class 1 radiation emergency was announced we stood the lowest in severity and management took the decision but no additional measures were required the AEC was notified immediately the reactivity levels and a detection of fission product contamination in the cover gas indicated that fuel melting had occurred since a significant amount of fuel melting could change the pressure characteristics at the core flow tests were conducted to determine whether several sub assemblies were substantially blocked or damaged for the next year the reactor was inspected and many fuel elements were removed for analysis investigations showed that two fuel elements had melted together and a third had bent but had little internal damage in total 3% of the reactors fuel had melted the free damaged assemblies needed a lot of force to be removed from the core necessitating parts as reacted to be dismantled on top of that the two bonded elements had to be cut apart for removal during the inspection of the reactor a foreign object was found blocking parts of the lower plenum starving coolant to some of the fuel elements this was discovered by draining considerable amount of coolant and the insertion of a borescope the obstruction was part of six zakone ium alloy panels used to direct coolant upwards to the reactor it was suspected that dynamic flow forces cause sufficient flutter in tour d'azyr chromium segments to break loose from their zoko neum machine screws however this did not occur until a relatively long period of operation of the system the objects were recovered in march 1968 to the core used a specially designed remote control tool cable was standing the radiation within the reactor the safety confinement of the primary coolant loop contains an estimated 10,000 carries of radiation however this presented a problem in repairing of reactor although free elements were damaged remained of the assemblies were still salvageable the reactor was pressed back into service in 1970 after repair works however by this time funds had been depleted for the project and the aging equipment meant that Fermi 1 was shut down for good in 1972 the accident of Fermi 1 was used as an example of the dangers of nuclear reactors where publications like we almost lost Detroit and 1975 Reader's Digest book by John G fuller a song with the same name was released by Jill scott-heron and Brian Jackson in 1977 however compared to many other atomic incidents the meltdown at Fermi one seems pretty tame as a confinement structure worked as it should and no official reports of radiation release were reported it comparison to the waltz mill extent in the last video it seems badly operators reacted quickly enough to prevent a more serious accident in 1975 it was officially classed as decommissioned by the AEC however after the formation at the NRC the definition of the units was reclassified to a safe store necessitating more decommissioning works in 1996 that works for decommissioning continued however the work again stalled in 2011 with a site keeping the safe store classification the site currently has a possession only license due to expire in 2025 it is planned about decommissioning will be continued for the purpose removing the remaining residual radioactive material and terminating the Fermi one licensed Fermi 2 is still an operation to stay providing electricity to local area the Fermi 2 operating license expires in 2045 I hope you enjoyed the video do you have any suggestions for any reactor based scrubs let me know if you like to support the channel financially you can on patreon from $1.00 per creation that gets you access to votes and early access to future videos I've YouTube membership as well from 99 pence per month and that gets you early access to videos check me out on Twitter and also if you want to wear my merch you can purchase it at my teespring store and always there to say is thank you for watching [Music]

Channel: Plainly Difficult

Views: 535,781

Keywords: Atomic, Nuclear History, Education, Plainly Difficult, Fermi nuclear power station, Fermi Unit 1, Fermi-1 meltdown, Nuclear meltdown, Chernobyl, qxir, nuclear reactor

Id: Y0iwe8T-PTc

Length: 11min 2sec (662 seconds)

Published: Fri Jun 12 2020