P. Bossew, German Federal Office for Radiation Protection, PLUTONIUM EMISSION FROM THE FUKUSHIMA ACCIDENT (pdf), 2013 (emphasis added): While much has since been published on environmental contamination and exposure to radio-iodine and radio-caesium, little is known about releases of plutonium […] The inability to cool the fuel led to melting of parts of the reactor cores (which parts exactly, is not yet well known) […] [Causes of the containment] ruptures and leaks […] are not entirely clarified […] explosion seems to have produced further structural damage in the containments, at the one hand, and on the other hand released large amounts of radionuclides into the environment. […] the fraction of Pu released into the environment can be expected to be higher [than] atmospheric releases only. Certainly some Pu has been released with liquid effluents and discharged into the ocean. […] The liquid discharges certainly also contained Pu. […]
‘Modern Marvels‘ History Channel (at 19:45 in): It is now 28 hours since the accident at Three Mile Island began. The men in the control room have no way of looking into the reactor…. it now seems clear some of the 36,000 slender tubes holding the uranium fuel have cracked, this is allowing radioactivity to escape into the reactor coolant water. It is imperative operators know how much radioactivity is now in the coolant. Too much, and the nuclear chain reaction could restart… Foreman Ed Hauser agrees to risk his life to take the readings. This is allowing radioactivity to enter the coolant water. He is in for an even greater scare when he draws the coolant water sample. The water from the reactor should be clear; instead he stares at a yellowish, fizzing liquid… It actually vibrates in his hand.