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Genie in a Bottle (What happened? (on January 3rd, 1961 the worst nuclear…
Genie in a Bottle
What happened?
on January 3rd, 1961 the worst nuclear reactor accident in US history had taken place (Casey,1998). at 9:10pm 6 fire fighters had been called to the SL-1 power plant due to numerous alarms at the plant notifying the firefighters. on the initial approach of the plant two firemen draped in breathing equipment entered the building with a radiation survey meter which read a maximum of 25 rems per hour, upon entering the meters were both maxed out. after a review of what to do next, two other fire fighters entered the support buildings to the right but found no-one and once again the meters were maxed out.
by 9:35pm they knew that 3 men were working the 4:00pm to midnight shift and that they were doing maintenance work on the reactor. on the third attempt to get the mens bodies from the reactor, 2 firemen went in with radiation gear and a 500 rem per hour survey meter. upon reaching the stairs to the reactor chamber the meter hit 200 rem per hour (fatal levels) and they turned back (Casey,1998). on the 4th attempt a fireman and a radiation technician entered the reactor chamber and they found that a nuclear reactor explosion had taken place. the men weren't found and so they returned outside as the rems reached 500 per hour.
on the next attempt a plant health physicist and a plant operations supervisor entered by 10:35pm. they ran up the stairs looking for the workers. at around 10:46pm the two men went out the front and wanted help from two other men and a stretcher. they had found one of the workers barely alive and unrecognisable and next to him was on of the other workers who had died (Casey,1998). the worker who was barely alive died later that night at 11:15pm. two other technicians entered after finding two of the workers as they were looking for the third one. they looked frantically until they looked above the reactor head to see the third man on the ceiling being pinned there by a control rod through his chest (Casey,1998).
Why it happened?
the events that transpired were the direct cause of the three servicemen that night. their job was to complete the installation of the 44 cobalt-aluminium flux measuring rods in coolant channels inside the reactor. these would help the engineers control the power within the reactor core. the reactor core contained vertical tubes of uranium, when active neutrons would be fired throughout the core which would strike uranium atoms which would release more neutrons to continue the process and this created immense heat which heated water into steam which turned turbines to create power (Casey,1998).
on first shift of the day on January 3rd, one of the workers had removed the 9 drive rod housings on the top of the reactor head (Casey,1998). these housings protected the mechanism used to remove the rods from the reactor and they covered a hole leading into the reactor. this second shift of the day had installed the flux measuring rods. the final shift of the day with our workers from the accident had started at 4:00 pm and their job was to put the housings and various components back together (Casey,1998). the workers didn't realise that the rods in the reactor that they were working on were high worth rods, this means that each rod regulated a large amount of nuclear reaction in the core.
in 1955 it was realised that the core could theoretically go critical with the removal of a single rod. the reasoning was that the reactor would run for 3 years between refuelling and have water constantly running to take away the heat so no-one would have any need to remove a rod during operation (Casey,1998). at the moment no reaction was taking place in the core because the all of the control rods were inserted into the reactor. for our workers they believed that to reassemble they had to lift the rod roughly four inches so that other parts could be slipped into place.
they didn't think there was enough space to put the washer and nut on the gear stud so they lifted it seven inches above the required position. at 9:00 pm they were done with the number 5 drive head and moved onto inserting the rod back down into the core. the C-clamp that was holding the rod up needed to be removed and the workers believed if they lifted the rod up it would be easier (Casey,1998). they believed the rod was simply stuck when this happened as it had occurred 40 times in the last 2 months so they had 2 of them use all their strength to try lift it up. as they pulled up the control rod blade broke loose and the rod shot upwards and the control rod was now not in the reactor core anymore.
with blade extracted there was now a critical mass of uranium inside the core, one neutron smashed into a uranium inside the core and released another neutron. this process occurred millions of times in a hundredth of a second and the core temperature jumped instantly to 3,740ºF, this made the metal components and the rod get vaporised and the fuel elements in the core melted (Casey,1998). the standing water expanded making the reactor bulge outwards. the spear like control rods ejected with the pressure of 35 atmospheres. with much of the Core melted or ejected out of the nozzles, the fissioning inside stopped just 2 seconds after the control rod had been lifted.
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Issues and findings related to people, workplaces & management
well the main cause of the problem was that the three workers caused the reactor to start by forcing the removal of one of the control rods which caused the core temperature to jump instantly to 3,740ºF, this made the metal components and the rods get vaporised and the fuel elements in the core to melt as well as making the water expand making the reactor bulge outwards (Casey,1998). the management team also had issues as they may not have properly informed the workers as to the consequences of what could happen if a single rod was removed. the management of the plant had also been very poor as there had been 40 complaints about control rods getting stuck yet nothing was done about it so there was a lack of action taken on managements part.
the workplace was also to blame as they didn't have any mechanisms or similar things in place to stop the control rods from being removed and causing a serious reactor accident.