Читать книгу Industrial and Medical Nuclear Accidents - Jean-Claude Amiard - Страница 57

Despite the partial melting of the reactor core and the significant release of radioactivity into the containment, the immediate radiological consequences to the environment were minimal. The containment has indeed fulfilled its role. The low releases to the environment were caused by the continued operation of a primary circuit effluent pumping system. Due to leaky circuits, hot contaminated water escaped into the building and vaporized, releasing the iodine and xenon it contained. These gases and vapors were sucked into the general ventilation of the building, through insufficiently efficient iodine filters, and released into the environment [IRS 12c].

The continuous radioactive releases consisted almost entirely of radioactive gases, with very small quantities of radioactive iodine. The highest measured ground dose rate was 1.3.10² C.kg⁻¹ (50 mR.h⁻¹) and the highest concentration of ¹³¹I was less than 3.7.10⁻⁶ Bq.cm⁻³ [HUL 89].

For example, honey samples were collected in the summer and fall of 1979 from hives within 16 km of the Three Mile Island generating station. None of the seven samples showed overall radioactivity significantly different from that of the control samples collected at a distance of more than 250 km [MOR 80]. These results confirm the findings of previous studies suggesting that only minimal quantities of ¹³⁷Cs escaped from the damaged Three Mile Island station after the accident.

In contrast, Field [FIE 93] found that the tongues of white-tailed deer (Odocoileus virgianus) caught in the 10 counties of Pennsylvania more than 88 km from Three Mile Island had levels ¹³⁷Cs higher than those of deer tongues tested in the counties surrounding the nuclear power plant. Similarly, in the thyroid glands of meadow voles (Microtus pennsylvanicus) trapped near the Three Mile Island nuclear power plant (1.9 km from the reactor) between April 6 and 16, 1979, the amounts of ¹³¹I were significantly higher than those in voles captured further away [FIE 81].