Uranium found in extracted nuclear fuel debris, radiation at 8mSv per hour

Uranium has been detected in nuclear fuel debris extracted from a Fukushima plant.

The radioactive element was found in one of the three meltdown-hit reactors at Tokyo Electric Power Company Holdings Inc.’s Fukushima No. 1 nuclear power plant.

The Japan Atomic Energy Agency revealed that the debris was extracted from the Fukushima Prefecture plant’s No. 2 reactor under the power company’s first trial removal that started in September and was completed on November 7.

Europium and americium were also found

It has been analyzed at a JAEA research facility in Ibaraki Prefecture. The collected debris is about 9 millimeters long and around 7 millimeters wide, and weighs 0.693 grams. Its radiation level measured 1-2 centimeters away stood at 8 millisieverts per hour, reported Jiji Press.

Radioactive materials, such as europium and americium were also found. These materials are formed by the fission reaction of uranium. The agency revealed that the melted nuclear fuel and reactor components that solidified resulted in the debris.

Radiation levels were roughly 8 millisieverts per hour

The debris measures around 9 millimeters by 7 mm and weighs 0.69 gram. It has a rough texture and is mostly reddish-brown, with some black or glossy areas. Radiation levels measured about 1 to 2 centimeters from the debris were roughly 8 millisieverts per hour, according to a report.

A retrieval procedure using a robotic arm that was initially scheduled for this fiscal year has been postponed to the latter half of fiscal 2025.

“The X‐6 penetration (an opening leading to the inside of the containment vessel) is being used to retrieve fuel debris at Unit 2. As with Unit 2, there is also an X‐6 penetration at Unit 3 that we expect to be able to effectively use as an access route for PCV internal investigations and fuel debris retrieval,” said TEPCO in a statement.

JAEA has maintained that fuel debris is the solidified melt distributed among fuel assemblies, control rods, and some other reactor materials. The fuel debris is considered to be distributed not only within the reactor pressure vessels but also in the primary containment vessels. It is necessary to understand the characteristics of fuel debris for the efficient and appropriate operation of removal, storage, processing and disposal of the fuel debris.

In general, the core melt mainly consists of fuels (UO2 and Zircaloy) and control rods (B4C and stainless steel), and it may even have reacted with the salt deposit from the injected seawater, pressure vessels (steel) and concrete at the bottom of the primary containment vessels. The constituents and characteristics of the solidified debris vary extensively depending on the conditions (temperature history, oxygen partial pressure) and the positions of solidification, according to JAEA.