On 13 February, a robot arm successfully picked up pebble-sized pieces of radioactive fuel at Japan's Fukushima nuclear plant. The plant operator, Tokyo Electric Power (TEPCO), sent a remote-controlled probe to the bottom of the plant's Number 2 reactor. It grasped five small pieces of debris from the fuel rods and lifted them a couple of inches.
The robot did not actually remove the fuel debris. This was just a test to see if it could be moved. The company plans to actually remove some fuel debris as a sample by March 2020. Robots have already been used to remotely observe the inside of the reactor. The purpose of the latest test was to see whether the fragile material would crumble when picked up. Actually removing the melted fuel is considered the most difficult part of the clean-up operation.
This marks a step forward in the clean-up, but setbacks continue and lingering problems remain. Just as the Japanese government was making a new push to ease import restrictions in Taiwan and Hong Kong, radioactive cesium above the legal limit was detected in a fish caught off Fukushima. And though scientists are gaining a better understanding of how radioactivity forms hotspots, a new release of stored radioactive cooling water appears unavoidable.
More than seven years after the accident, fear of radiation now poses a greater obstacle to the economic recovery of the region’s seafood industry than any actual physical damage. Several countries have put in place bans on Fukushima’s seafood as a preventative measure.
However, By mid-January, Japan had racked up three years with no fish or shellfish exceeding the government’s maximum level of 100 Becquerels per kilogram of cesium in inspections conducted by Fukushima Prefecture in coastal waters. In 2018, over 6,000 samples representing about 200 species were tested, and the highest value detected was 51 Becquerels per kilogram. A cesium level exceeding the limit was last detected in a stone flounder in March 2015, at 140 Becquerels per kilogram.
But at the end of January, the streak was broken, as a cesium level of 161 Becquerels per kilogram was detected in a skate. As a safety measure, skates from Fukushima will be taken off the market. The prefecture will collect more samples for research and the central government will judge the safety of the fish.
The timing was bad, as Japan was using the positive test data to push for lifting of import bans in Hong Kong and Taiwan as well as domestic promotion. The Reconstruction Agency ran a television commercial advertising farm, fishery, and forestry products made in Fukushima Prefecture for about a week to dispel rumors about the safety of products from the prefecture.
On a visit to Hong Kong at the start of February, Fukushima Governor Masao Uchibori met with officials of an industry association related to Japanese food, and with senior Hong Kong government official in charge of import regulations. Hong Kong eased its restrictions on food from the four neighboring prefectures of Ibaraki, Tochigi, Gunma and Chiba last year, but has maintained restrictions on Fukushima products.
At the end of November, despite Japanese attempts to move the government to lift its ban, Taiwan voted in a referendum to uphold an import ban on agricultural products from Fukushima and the same prefectures as before.
Japanese scientists made a breakthrough in understanding hotspots, as it was found that some cesium is in the form of small glass-like micro-particles, and that these are prone to washing off of slopes with rain and forming hotspots where they settle. Though the study focused on hotspots on land, it is possible that such hotspots also form in the ocean as well and may account for anomalous data.
Hotspots aside, the general trend of improved radiation levels may be reversed soon, as Japan plans to discharge cooling water from the Fukushima nuclear plant containing radioactive material into the ocean. The government has been constructing a tank farm to store an ever-growing amount of cooling water, but is running out of space and may have to begin releasing some of the 1.09 million tons of water stored in 900 tanks.
TEPCO reports that multiple facilities including a multi-nuclide removal facility (advanced liquid processing system or “ALPS”) are used to treat the contaminated water, and after the concentration of cesium and strontium contained in the water is reduced, ALPS removes most of the radioactive materials except tritium.
However, some newspapers in Japan and abroad are questioning whether the reported low levels are correct, claiming that some samples have exceeded standards. The situation is confused, as there are various lots of water with differing levels of radiation, due to troubles or improvements in the treatment systems over time. Some salt water from which cesium was removed still contains strontium, but improvements in the filtering device means this water is no longer generated. Water in which strontium has been removed by the improved filtering device will be treated by the ALPS system to remove most other radiation. And finally, there is water that has gone through the ALPS system, but which could not be fully treated due to troubles with the system. This water will have to be treated again.
Uncertainty about the actual condition of the water to be released and the safety of the remaining tritium may provide cover to nations maintaining bans on seafood from the area.