 It is the 21st of June 1990 and an operator is called out to an irradiation facility at Sarek in Israel. He notices a problem. The transport mechanism of the irradiator has gotten jammed. Based with the workload pressures and confronted with two conflicting indications on his control panel, the operator decides to try and clear the jam himself. The safety systems on site should prevent him from entering the irradiation room, but a known exploit of turning the system on and off multiple times releases the lock to the room. He enters to inspect the blockage. He leaves to retrieve a cart and then enters again. Within minutes, feeling his eyes start to burn, he flees the room but it was too late. He received a full body deadly radiation dose. Despite intensive medical care, he would die 36 days later. Today we're looking at the radiological accident in Sarek. As such, I'm going to rate this subject here free on my disaster scale but also free on my legacy scale. Although fairly unknown, the event shows the importance of safety procedures and the risks you are exposed to if ignored. Sarek has been the centre for Israeli nuclear research ever since the 1950s and the construction of the country's first research reactor. An irradiation facility in Sarek was built in the late 1960s. The project was a joint venture between the Netherlands and the Israeli Atomic Energy Commission. Although within the Sarek site, the facility is operated under a separate company by the name of Sorvan Radiation Limited. The radiation facility employed a model JS6500 gamma steriliser designed, manufactured and installed by Atomic Energy of Canada Limited. The unit uses Cobalt 60 as its radioactive material. The facility is used to radiate and thus sterilise prepackaged medical products amongst other items. Irradiation of an item can take many hours as it is passed through the machine in steps. Packages to be irradiated are packed in cartons and two or three of these cartons are stacked and taped together for passage through the irradiator. The boxes move through the machine via a roller system similar to the ones used on other types of production lines. Except in this case, the items move past the radioactive source multiple times in a Z-like shape to receive the required dose over two levels. To achieve movement of the carton boxes, pistons are employed at each changing direction. The amount of time the item stays in each position is controlled by a timer and when a preset timer is passed, the piston is activated. Like with all radioactive materials, its safe movement and control are vital to the overall site's safety and SREC was no different. As personnel may need to enter the irradiation room and being confronted with a whole load of Cobalt 60 would ruin most people's day. The Cobalt 60 was mounted on a source rack consisting of six modules containing multiple pencils of the radioisotope made up of two source elements within. To even out the dosage, dummy pencils were also installed in each module, totaling 42 pencils per module. When not in use, the rack is stored in a water tank and this shields staff from gamma radiation. To raise the source rack to its irradiation position, cables and hoists are used, powered by a pneumatic piston. As a fail safe, if the piston runs out of air, then via the power of gravity, the rack is plunged back into its water pool. The state of the rack is indicated to operators on the control panel via a simple micro switch, but this needs regular adjustment to give the correct information. During the 1970s and 1980s, similar systems had experienced blockages and jams. As such, the manufacturer issued a notice to install a metal shroud. However, at Sarek, this was not done. So how was the system made safe from any unwitting intruder to the irradiation room? As you don't want something like the Hanoi radiation incident to happen again. The operators controlled the system via a control panel outside the irradiation room. There are three key switches for power on, source raise and machine on. The first two control the movement of the source and the third allows movement of the transport mechanism while the source is raised. The irradiation program is interrupted and the source automatic lowered if any of the following occur, being tripped by a safety interlock or if sensors detect high temperatures in the irradiation room, low pressure in the pneumatic hoist system or misaligned cartons jamming the transport mechanism. If a product jam stops the source rack from returning to its pond, then an alarm should sound to the operator. To enter the irradiation room, a key switch that operates the door lock solenoid is linked up to a radiation monitor. Need is to say if radiation levels are registered above background, then the door cannot be unlocked. To gain access to the room, the operator first has to press the monitor test button. The radiation detector checks the reading in the room. If OK, the button can be released. Then this is checked again to make sure the room is at background levels. After this, the lock will be released. All of this is also interlocked with the source rack position sensor. If not in the pool, then the door also cannot be released. I should say, also if the radiation alarm is going off, then the test cannot be attempted as the lock to the door is completely de-energised. Once entrance to the room is granted, the operator must make their way for an area called the maze. Finally, entering the irradiation room. There is emergency cut-off pool string attached to the wall of the room, which if pulled will drop the source rack back into the pool. Of a total workforce of 20 at Sorvan, there were four operating staff, a senior technician who had worked at the plant since it was built in the late 1960s and three technicians. Each had been certified and had at least one year's practical experience, which was a requirement to operate the facility. Due to the equipment being from Canada, much of the operating manuals were in English. Only a short list of routine operating and safety instructions, including the procedure for entering the irradiator, had been issued in Hebrew. This led to some confusion as not all the operators were very proficient in English. The irradiator was often in operation 24 hours a day due to the high workload, but it was only staffed on a regular day shift. The conveyor was long enough to hold five to seven hours' worth of cartons. Before leaving, at the end of the day shift, the staff loaded the input conveyor to its full capacity and completely unloaded the output conveyor. At around midnight, an operator would go to the facility to reload and unload the conveyor for the night. Due to the facility being unattended, the source rack down indicator is hardwired to the emergency control centre of the SUREC Research Nuclear Test Centre, and is staffed 24 hours a day. In the event of a malfunction, the on-call operator would be requested to attend and rectify any faults. This leads us onto the summer solstice of 1990 and a jam occurring at the irradiation facility just after 5pm. At around 5pm on the 21st of June 1990, a jam occurred in the transport mechanism in the irradiator room. This caused cartons on other parts of the conveyor to burst open. One carton was pushed towards the source rack. The overdose timer detected the jam and the control system automatically initiated the source rack to be Displaced cartons on the lower conveyor stopped the rack from lowering back into the pool. The micro switch on the source hoist malfunctioned and incorrectly indicated that the source rack was fully down. The product jam was registered at the emergency centre at the SUREC Nuclear Research Centre and the SOARVAN duty operator was informed at home by telephone. An unqualified staff member silenced the alarm by disconnecting it from the control panel by 5.35pm the on-call operator had attended and reconnected the alarm. On the console the product jam and source down light were illuminated. Confusingly the radiation alarm was sounding indicating a high level of radiation. These were all conflicting indications for the operator. The situations like this two operators are required to be in attendance but strangely he decided to deal with the issue alone and this is most likely due to production pressures. Based with conflicting information the operator decided to ignore the radiation alarm and believed the source rack was safely in the pool. Little did he know but the vital micro switch used to prove the source rack location had not been adjusted correctly and was thus defective. To silence the alarm the operator went behind the console and disconnected the cable from the radiation monitor to the alarm and control circuitry. This should have meant that the door to the radiation room could not be opened as the radiation monitor test would automatically fail but there's a little knack to bypass this. The key from the machine switch can be removed and inserted into the power switch which if cycled on and off several times while pushing the test button tricks the monitor into thinking that he's reading background radiation. After bypassing the interlock the operator entered the maze. He took with him a small radiation monitor but did not calibrate it. As he entered the room he should have been greeted with the blue glow from the source rack in the pool caused by a Cherenkov radiation. Not noticing that he still continued in the side. The operator left the room to fetch a cart. After re-entering the room he began to remove the damaged cartons from the conveyor. Quickly he began to feel a thumping in his head and a burning sensation in his eyes. He fled the room and contacted at 5.45pm who's superior the senior technician and explained what happened. Not long later he felt sick and with his head still throbbing started to retch. The senior technician telephoned the emergency centre at Sorek Nuclear Research Centre. An RSO from the research centre came to assist and after being explained on how to gain access to the room went into the maze with a dosimeter. His reading was at 0.5 cv. An hour. The 32 year old operator was transported to the Ichilov Medical Centre in Tel Aviv where he was examined by a physician 2 hours and 15 minutes after exposure. At this point it was thought that his exposure was 10 to 20 grey over a period of around 2 minutes. As a note 4 grey has killed people before. For the first few days he vomited regularly each day and continued to fill nausea. By day 4 he was given a bone marrow transplant. The white blood cell count continued to drop rapidly on day 5 and by day 22 the symptoms continued with a fever of 40 degrees centigrade. Liver function continued to deteriorate in testing and the sickness increased. By day 34 he was confused and bedridden. At 2 am on the 27th July 1990 day 36 the patient died. It was found during the autopsy that death was linked to his radiation exposure and GVHD graft versus host disease. This happens when after a bone marrow transfer the white blood cells from the donor start attacking the recipient which ultimately can cause organ failure. After the accident the source rack was returned to its safe position later that evening on the 21st of June after taking advice from the suppliers headquarters in Canada. Investigators set out to find out why the operator acted as he did. As noted in the IAEA reports that a properly translated manual for the operators could have helped with fault finding as well as stricter training by properly configuring any portable radiation monitors before entry to an irradiation area. Moreover if the operator had followed the rules and requested another member of staff to assist then the dangerous path he went down likely wouldn't have happened. It was also found that entrance security to the irradiation room was easily bypassed by playing with the console by repeatedly cycling the key in the power switch. Also the micro switch needed proper adjustment was found to be faulty leading to the incorrect indications on the operator's panel but essentially preventing the jam from the start would have averted the radiation incident. If the company had heeded warnings in the 1970s and 80s and installed the recommended shroud then the jam and the source rack might not have happened at all. Needless to say these were key recommendations given from the IAEA to the facilities management. It is a shame that pressure to get production running again led the operator to undertake actions that turned out to be pretty deadly but as they say rule books are written in blood. This is a plain default production. All videos on the channel are created commons attribution share alike licensed. Plain default videos are produced by me John in the currently raining southeastern corner of London UK. Help the channel grow by liking commenting and subscribing. Check out my Twitter for all sorts of odds and sods as well as future hints on videos. I've got Patreon and YouTube membership as well so if you fancy supporting the channel financially you can check them out. And all that's left to say is thank you for watching.