A Brief History of: The HTRE no.3 Reactor Meltdown (Short Documentary)

[Music] nuclear reactors have found many different applications from experimental breeder reactors to compact reactors inside submarines all the way to reactors capable of powering cities as reactor designs develops uses outside of stationary applications were considered one such was empowering of a vehicle which could be feasible in an environment where weight isn't a priority that can be overcome with power for example in a railway locomotive setting however a number of experiments involving lightweight units in aircraft design were undertaken in the u.s. jr. 1950s power excursions in a nuclear setting is not a good thing and as such may have been an often covered subject on this channel and again instance with experimental reactors are not a rare subject for me Iver however the HTR e number 3 is something new to me and that is the use of atomic reactor design to be used on board an aircraft on the plainly difficult screwup scale I'm gonna place it here I thought she'd a dream of nuclear-powered air travel didn't come to fruition how the program was a vital part of nuclear history in late 1946 the US Army Air Force looked into the feasibility of building a reactor small and powerful enough to be used in an aircraft the nuclear energy for the propulsion of aircraft or NEPA project was started to look into this new power was replaced by the aircraft nuclear propulsion project in 1951 a nuclear-powered jet engine in principle replaces the heat generated from burning fuel with heat generated from a nuclear reactor this system had a major advantage over conventionally powered aircraft and that was the range between refueling the concept of atomic power in an aircraft made most sense in the application of a strategic bomber much like a submarine the use of nuclear power vastly improves the operational endurance operational time of such a bomber between refuelling was fought to be able to be counted in number of days rather than hours meaning that an aircraft could circle the earth ready to strike without for dangerous in-flight refueling process although the advantage could potentially revolutionize a country's ability to strike two nuclear war the concept had one glaring disadvantage that was the weight associated with the operation of a nuclear reactor in the form of its shielding in aircraft design weight is a number-one concern as if your plane is too heavy it will be limited on it's available payload or were still not even be able to take off this completely conflicts with a need for a reactor to be safe and not a radiating around it traditionally fixed shielding of lead or concrete has been used which is surprisingly not very light without adequate shielding you would radiate your way through pilots very quickly and in the event of a meltdown rain molten nuclear waste onto any unsuspecting person on the ground designers for fact await sacrifice of traditional aircraft fuel might counteract the weight of a reactors shielding the ANP program set out to design construct and test such a reactor light enough for an aircraft aiming to reduce the weight from tens of thousands of tons to just over 100 tons the program pursued two different types of propulsion system by two different companies General Electric's directs air cycle and Pratt & Whitney's indirect air cycle respectively we might be looking at the latter today but we may do in the future the former by General Electric began development starting with its first test reactor system in 1956 the first let's look at how the direct air cycle system works but ge design used an off-the-shelf j-47 jet engine and modified it for nuclear power the engine had a long life with the US Air Force with over 30,000 units being constructed air is sucked into the engine by the front turbine and his past fruity reactor with some taken to call the components the majority of da is heated by the chain reaction on its journey through the reactor and then travels into a lower plenum is then passed back through the jet engine in turn powering a turbine connected via sharp to the inlet turbine the air is then exhausted to atmosphere to startup the powerplant conventional jet fuel was used to spin the turbines up to the required rpm once this was achieved the reactor was slowly powered up by withdrawing the control rods once the reactor was up to temperature conventional fuel was shut off that is the basic overview of the concept how that is implementation varied over the project lifespan this leads us on to the heat transfer reactor experiment the program took place at a Idaho National Laboratories north test area which is around here in a map the first setup was the HT ry1 this was a direct air cycle reactor that used nickel chromium and uranium oxide dispersion fuel elements water served the combined function of moderator and structural coolant HT ry1 successfully operated a jet engine on nuclear power in January 1956 and faretta year racked up over a hundred and 50 hours of operation how the HT ry1 was more of a proof of concept and wouldn't be considered usual in an aircraft this leads us onto the next step of the project HT r e - 2 h TI e - 2 reactor was a modified version of the HT re - one allowing removal of the center fuel assembly the removable module allowed experimentation with different core materials and configurations which was essential in paving a way for a unit capable flight finally the HTR e - free was a culmination of the advancements of the previous experiments and hoped to be the basis of a production unit it was built in a configuration ideal for incorporation into an aircraft by having the fuel and control elements mounted horizontally reducing the overall height at a power plant the 175 megawatt capable unit was delivered to the initial engine test facility on the 20th October 1958 HT r e - r e was mounted to a d1 o 2a assembly and consisted of a reactor primary shield external auxiliary shielding engine reactor ducting a single chemical combustor with surrounding auxilary shield accessories and two modified j-47 turbojet engines but unit took the same fuel as the HTR e - one nickel chromium and uranium oxide but with a hydride is econia moderator the moderator was a hexagonal array of of 150 moderator cells surrounded by a beryllium reflector the reactor core had a total diameter of 51 inches and the active core length was 30 point 7 inches with an overall length of 40 3.5 inches each of the moderator cells had a circular tube cut into it for its full length this was used to house a fuel cartridge in each cell director had 48 poison-type Control words made out of ear opium oxide consisting of free automatically controlled dynamic 30 shim for fine-tuning and 15 safety rods arranged fret liqueur in both the center and the outer regions of the reactor the reactor had an independent scram facility from the control system in the case of an emergency the whole reactor was air called provided by the air induction from the jet engines assuring of the unit consists of water LED and steel and had an expected life of a thousand hours of operation here EXO also had a plug placed at the front and rear this leads us onto November the 18th 1958 at 8 p.m. as reactor was new operators wanted to conduct multiple low power test runs building up to a full power test early on in that day a test run had achieved 2.06 megawatts but the evenings test was scheduled to follow a similar run but increase the power to point 12 megawatts pretest all equipment and instruments checked out to be okay by the operators just after 8:00 p.m. the test had begun and all seem to be working well to external blowers were used to growing enough airflow passing through the reactor and out to the number two jet engine turbine but jet engine motored at approximately 600 rpm to raise the power to the expected level the servo control control wards were withdrawn in a set sequence all of the shim and dynamic rods needed to be withdrawn equally at around 8:20 to p.m. the pair of the reactor increased as expected surely before the power reached the demanded level the indicated flux level fell on a linear flux instrumentation quickly the indicated power level rapidly rose the control systems scram the reactor automatically the fuel temperature went off the maximum scale monitors at 3000 found height around 25 minutes after the dramatic power increase operators to soils use a diesel powered air compressor to blast air for the reactor to call it down more than the electric blowers could radioactivity had been released and a narrow band of fallout occurred contained within the research laboratory site limits around point zero four million taejun's per hour was recorded free thousand feet away from the test site five miles away the measured fallout was 1.25 micro Curie's per square meter but iodine 135 at around one mile from the test site four hours post event to milli Ron to Jen's per hour were recorded the reactor had experienced an unexplained power excursion and a potential meltdown it was estimated at the time of the event but 717 megawatt seconds was experienced a power level like that would be more than enough to cause serious damage to the fuel elements and it did the power plant was moved to the site hot shop but dismantling an inspection to reach the cord a rear plug was removed revealing fuel damage the core was removed and it was found that some fuel assemblies were stuck inside their moderator tube necessitating them to be cut free many were able to be removed freely her that every fuel Assembly had received some level of melting towards the center of the core someone elevator sales and control wars had experienced damaged however many were in every usable condition after removal an inspection of the few elements it was found that although the reactor scram was triggered by excessive fuel heat some parts of the fuel had already melted excessively this was in part due to the low power electric blowers not providing enough cooling air through the core for the power level being put down luckily due to the modular design of the power plant but damaged fuel control and moderator components were relatively easy to replace when the reactor stripped no cause for failure was found with the control words fuel elements or moderator this prompted further investigation into the electrical control and instrumentation of the reactor as the scoured met the information the operators were receiving from the reactor was lying to them it was found that the primary cause of the incident was that the linear flux circuitry was unable to indicate true reactor power because of the presence of electrical noise filters in the circuitry the incorrect information caused a false demand to the control system withdrawing dynamic and shim rods when they did not need to causing excessive fission these filters had been in both the HT ry1 and - but on free the wiring diagrams did not show their use the problem was forever exasperated by incorrect use of 800 volts instead of 1500 volts meaning the high resistance noise filters affected the signal the reactor was repaired and set up again for testing reaching its full power in 1959 and things went well logging 87 hours over its intended hundred hours of full power testing the reactor was used all the way up until the ANP project was cancelled in 1961 in total costing around 1 billion dollars even low nuclear power flight didn't happen the lessons learned from compact reactors have been far-reaching the program was considered so influential that the assemblies of H TR e 2 and number 3 were preserved and put on display outside the UPR 1 building for the public to see I hope you enjoyed the video if you'd like to support the channel financially you can on patreon from one dollar per creation that gets you access to votes and early access for future videos I have YouTube membership as well for online time pits per month and that gets you early access to videos as well check me out on Twitter and also if you want to wear my merch you can purchase it at my teespring store nobody said to say is thank you for watching [Music]

Channel: Plainly Difficult

Views: 513,391

Keywords: Atomic, Nuclear History, Education, Plainly Difficult, HTRE, heat transfer reactor experiment, EBR-1, Idaho, Idaho National Laboratory, nuclear reactor, atomic plane, general electric

Id: db97RSlALYw

Length: 12min 29sec (749 seconds)

Published: Fri Jul 03 2020