Curium-244 detected for first time outside Fukushima plant – Requires lead shield 20 times thicker than Plutonium-238
June 14th, 2011
Curium: As compared to a competing thermoelectric generator isotope such as 238Pu [Plutonium-238], 244Cm [Curium-244] emits a 500 time greater fluence of neutrons, and its higher gamma emission requires a shield that is 20 times thicker — about 2 inches of lead for a 1 kW source, as compared to 0.1 in for 238Pu.
TEPCO Press Release, June 11, 2011:
[...] Since plutonium and uranium were detected from the samples at the 3 periodic sampling spots collected on April 11 and 25, we conducted americium and curium analyses. As a result, americium 241, curium 242, 243, and 244 were detected as shown in the attachment 3.
Today, we informed the Nuclear and Industrial Safety Agency and the government of Fukushima Prefecture of the results.
First out of the first nuclear power plant site in the town trace curium Hukushima Ookuma, Kyodo, June 13, 2011:
Ministry of Education, approximately two primary – the first from the soil collected in the town Hukuzima Ookuma 3 km Fukushima, announced that it has detected trace amounts of radioactive curium. Outside the premises at the primary site has been detected for the first time. The ministry “has been released to the outside by accident. But internal exposure to radionuclides that need attention,” he explained.
Curium was believed to be from this time with the operation of the reactor plutonium. Detected in soil collected on May 1 and April 29 at the point of the town Ookuma 2. On the other hand, even trace amounts of americium were detected from the soil, the ministry is “a small amount detected in the atmosphere by nuclear tests in the past” has said.