Exposure of nuclear workers to radiation that results in exposure at higher limits than before the Fukushima Dai-ichi emergency began has been OKÂ’d by the Japanese government and Toyota Electric Power Company (TEPCO). Â TEPCO employees are working within the new exposure limits.Â However, additional help is needed.Â The Fukushima 50, a relatively small cadre of 300 workers (about 45 of whom are temporary workers) has been working extended shifts daily to thwart the daily emergencies and the overall threat of release for four weeks now.Â They are exhausted and they are reaching even the new limits on their dosimeters.Â TEPCO has called in contractorsÂ… who want nothing to do with the new limits.Â They say the new limits arenÂ’t safe, and that not all their workers would accept them.
The new accumulative radiation limit was established four days after the earthquake and tsunami struck, based on the need expressed by TEPCO to allow workers to work longer shifts in proximity to radiation sources.Â If four days seems an awfully short amount of time to do the studies necessary to demonstrate safety under the proposed limits, rest assuredÂ… no such studies were, in fact, done during those four days.Â The decision was based on an assessment of relative risk, and that assessment had been done years before.
The original limit, 100 millisieverts, was raised to 250 millisieverts based on Â“Â…a view of the International Commission on Radiological Protection that sets the upper limit in an emergency situation to a dose of 500-1,000 millisieverts.Â” Established radiation limits in these situations, similarly to chemical exposure or explosion risk, are usually the product of studies which lead to a statistically safe level of exposure.Â A Â“safety marginÂ” of at least one order of magnitude (10th power) is then applied to insure, as completely as possible, that the actual risk is zero.Â Thus, the emergency limit of 500 Â– 1000 is the statistically Â“safeÂ” limit, and the standard limit of 100 is the Â“safety marginÂ” adjusted limit.Â The actual job of calculating safe limits in this case requires a little more work than this paragraph may suggest.Â One’s “gut feeling” will not suffice.
TEPCO has said it will not push the issue, because if workers will not accept the new emergency limit, they cannot be forced to.Â People fear radiation, with good reason.Â It kills insidiously and painfully.Â Nonetheless, perhaps, if the company and the regulatory agencies had taken the time to explain the etiology of the various limits, it would not be necessary to forgo the value provided by the new limits.Â After all, when people understand what the risks and rewards truly are, and how they are developed, they are often more comfortable with the situation.