Employees at Tokyo Electric Power Company (Tepco) have inserted an endoscopic camera into the number two reactor of the Fukushima Daichi nuclear power plant. The footage, released just a few days ago, is the first from inside the damaged reactor since the Japan earthquake of March 11, 2011.
Besides assessing damage, the probe was intended to compare independent measurements against existing sensor-data. The temperature as measured by the camera probe matched the temperature measured by the temperature gauge outside the reactor.
However, the probe was unable to reach the surface of the cooling water, suggesting it rests at a lower level than sensor data indicates. The difference between the sensory data and the true water level may be half a metre or more. Despite this, officials still don’t feel the nuclear fuel is exposed to air, based on other information.
The reactor was announced to have reached cold shutdown last month. This means that since the water has dropped below boiling, the nuclear fuel is no longer able to reheat as water is evaporated away. It is considered stable at this point.
Also visible in the 30-minute video is what seems very much like rain inside the reactor. Since the cooling water is still near to boiling, it seems that water vapor is continually condensing into drops near the top of the container and falling back down to the pool.
The video (which you can watch by clicking through to the BBC link) included several instances of white static, caused by the high background radiation affecting the visual sensors of the camera. The footage is often distorted for the same reason.
The pipes appear to be undamaged, and, insignificantly, paint inside the container can be seen to have peeled off due to the extreme temperatures over previous months.
Tepco is still trying to identify everything seen in the video. However, the information learned from the video should help them to maintain stability in the reactor. One major question that could not be answered with certainty is whether liquid nuclear fuel actually fell to the concrete bottom of the containment vessel, as in a true meltdown situation.
Now that the situation is stable, further investigations can be made. It’s still far too hot, both in terms of temperature and radiation activity, for a person to enter. But Junichi Matsumoto, acting head of Tepco’s nuclear locations, said the company had plans to develop a small robot for a closer look than the probe has been able to give them.
8,000 people were initially evacuated from the area due to high radiation levels resulting from the plant disaster. In many areas, residents are still unable to return home. One suspects the ongoing monitoring and eventual clean-up of the former Fukushima Daichi plant will stretch out to many more years to come.
Photo credit: Digital Globe