Machinery Safety 101

Worse than Worst?


Past and current International Nuclear and Radiological Event Scale for the Fukushima Dai Ichi disaster
Updated INES Level for Fukushi­ma Dai Ichi

The increase to the incid­ent level at the Fukushi­ma Dai Ichi nuc­le­ar plant today by the Japan­ese Nuc­le­ar Reg­u­lat­ory Author­ity has brought the con­tinu­ing dis­aster at the crippled plant back into the head­lines. IEEE Spec­trum has pub­lished a series of art­icles recently writ­ten by Bill Sweet on the Fukushi­ma Dai Ichi nuc­le­ar dis­aster. From the human per­spect­ive, this has been a ter­rible dis­aster, although by some accounts not as bad as Chernobyl. I am not qual­i­fied to speak on the tech­nic­al aspects of nuc­le­ar power, but from a risk assess­ment per­spect­ive, this dis­aster brings some inter­est­ing les­sons. I explored some of these ideas in anoth­er art­icle called “How Risk Assess­ment Fails”. If you want to learn more about the dis­asters, I encour­age you to check out Mr. Sweet’s articles:


You might also want to read the New York Times’ art­icle “Japan­ese Work­ers Braved Radi­ation for a Temp Job”.

Much can be learned from the nuc­le­ar incid­ents and acci­dents at Three Mile Island, Chernobyl, and now Fukushi­ma. As engin­eers and safety prac­ti­tion­ers we need to be acutely aware that basing our assess­ments on single fault ana­lys­is, and the cor­res­pond­ing fail­ure to exam­ine the pos­sib­il­ity of com­mon cause fail­ures that can res­ult in epic scale dis­asters like these is false secur­ity. You can­not hide from con­sequences like these. We must begin to con­sider the ‘worse than worst’ scen­ari­os that exist in our designs and in our work­places. We may not be deal­ing with risks on a nation­al scale like those present in these facil­it­ies, but the con­sequences to those we work with can be just as devastating.

4 thoughts on “Worse than Worst?

  1. Even though the Japan­ese insisted that the dam­age will be min­im­al have no doubt we are look­ing at anoth­er Chernobyl. Even though they are the fore­most coun­try in the world deal­ing with dis­asters such as earth quakes and tsuna­mis this is abso­lutely cata­stroph­ic for the entire area .

    1. I agree. I believe that it will be dec­ades before the prob­lems cre­ated by the fail­ures at Fukushi­ma Dai Ichi could be con­sidered adequately con­tained. Like Chernobyl, I believe that the ocean sur­round­ing the east side of the plant and the area inside the 20 km exclu­sion zone will show the res­ults of expos­ure for the fore­see­able future. Unlike Chernobyl, I believe that the Japan­ese will entomb the plant rel­at­ively quickly and will mon­it­or the con­tain­ment effect­ively. Chernobyl’s react­or has yet to be con­tained because the Ukraine does not have the money to com­plete the work, and the inter­na­tion­al com­munity has not made good on their com­mit­ments to fund the cleanup and containment.

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