The moral of today’s criticality accident is “if you don’t
learn from the past, you’re doomed to repeat it.”
On September 30, 1999 (yes this was just 17 years ago), the
JCO fuel fabrication plant in Tokaimura, Japan. The facility was authorized to use the
image below. In a comment on my last post, I made the statement that sometimes
the person who designs the system causes the accident by making a system that’s
so inconvenient that avoiding the authorized procedure is simpler.
The authorized design was terrible. The drain for the final tank
was 10 cm (~4 in.) from the floor and it was needed to fill 4 L bottles. Just
stop reading and think of this, an iPhone 5 is 4.87 inches long. Imagine
filling a bottle on the ground with less distance from the spigot than the length
of an iPhone. Instead of working within the system, operators used the
procedure below.
The original procedure had a lot of controls to ensure that
materials didn’t concentrate in areas and become critical. By hand mixing the
solution and transferring it using flasks, there was no guarantee that
concentrations were safe. On September 30th, the gamma radiation
alarms at the facility sounded in the building and two adjacent buildings.
Criticality continued 20 hours until action was authorized. Residents within
350 m of the plant were recommended to evacuate and residents within 10km were
recommended to stay indoors due to airborne fission products. (Don’t worry 90%
of people in a 350m area received less than 5mSv and contamination to the area resulted
in readings from plant life of less than 0.01mSv)
Two workers that were involved in the pouring of the
solution were severely exposed. One operator died 82 days later, the other died
210 days later. A third operator that was at a desk a couple of meters away was
in the hospital for 3 months.
The people of the facility felt pressure to produce fuel and
with a weak understanding of the factors that could lead to an accident, they
did not understand the possible consequences of their actions. Additionally,
officials for JCO felt an accident wasn’t even possible. Nuclear material is
only “safe” if you treat it like it’s not and not learning from previous
accidents meant JCO officials got cocky, didn’t educate their operators, and
eventually this resulted in an accident.
A hose coming from the spigot might have made that a less painful process. What was the one indecent we learned about in Crit Safety, where the operators tilted a tank to make it pour faster? I thought that's where this was going
ReplyDeleteWho are the JCO? Is that a state-owned Japanese company? A quick google search tells me they are the "Journal of Clinical Oncology." Something tells me that's not right.