Hence, surface characterization analyses were performed to elucidate the chemical nature of the AD. The surface analyses also indicate that silicon and cesium levels are spatially correlated, a fact pertinent to understanding the adherent cesium activity. Six samples were obtained from the TMI core rubble bed in September A description of the sampling and analysis methods is presented, along with the results of chemical and radiochemical examinations.
Correlations are performed with the core structural composition and predicted fission product concentrations and inventories. The core debris is a mixture containing UO2 fuel, zircaloy cladding, and control materials silver, indium, and cadmium ; poison rod materials; and structural materials.
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Radionuclide concentrations are similar at all locations. The principal radionuclides measured are strontium, iodine, cesium, and cerium Results of radiochemical, elemental, and particle size analyses of samples collected from Three Mile Island Unit-2 TMI-2 are presented. The total quantities of fission products, fuel, and core material elements measured on Reactor Building surfaces, in the water and sediment in the basement, and in the reactor coolant system water during basement sampling are also presented. This paper describes the main features of the chemistry of iodine that contributed to the low concentration of radioactive iodine observed in the gas phase following the Three Mile Island-2 nuclear reactor accident.
The very low concentration of iodine in the gas phase was one of the most important and, to some, surprising feature of the accident. The behaviour of radioactive fission products, such as iodine, during a loss-of-coolant accident is a complex function of their chemistry in UO2 fuel, in the gas phase and in the aqueous phase.
The main focus of this paper is on the chemistry of iodine in aqueous solution, including thermodynamic and kinetic calculations of aqueous iodine reactions, such as hydrolysis, disproportionation, reaction with organic material and radiolysis. From an examination of the chemistry of iodine in nuclear fuel, in the reactor coolant system, and in the containment building, it is concluded that the chemical conditions at Three Mile Island-2 favoured low iodine volatility. Samples of actual high-activity-level water from TMI-2 were used to develop a chemical processing flowsheet for contamination of the water and concentration of the radioactive contaminants in a form suitable for disposal.
The process included 1 sorption of the bulk radioactive materials, cesium and strontium, onto an inorganic ion exchanger; and 2 sorption of the remaining traces of cesium and strontium plus anionic contaminants, such as antimony and ruthenium, onto standard organic ion exchangers. Prior to its use, the initial step removal of the bulk radioactive materials was improved by evaluating mixtures of zeolite ion exchangers and selecting a combination which enabled a significantly greater volume of water to be processed through the exchanger.
Nearly 3 million gallons of water have been processed by these two systems. SDS continues to process water that has been used for decontamination. The systems are fundamentally different in that the SDS uses zeolites to remove radioactivity from the water and the EPICOR system uses standard organic ion exchange resins. The operational history of these systems is discussed in this chapter.
The Three Mile Island Unit 2 Reactor TMI-2 has sustained core damage creating a significant quantity of fine debris, which can become suspended during the planned defueling operations, and will have to be constantly removed to maintain water clarity and minimize radiation exposure. One of the primary components In the DWCS is a custom designed filter canister using an all stainless steel filter medium.
The full scale filter canister is designed to remove suspended solids from microns to 0. The filters were challenged with simulated solids suspensions of and ppm in borated water ppm boron. Test data collected includes solids loading, effluent turbidity, and differential pressure trends versus time. From the proof-of-principle test results, a full-scale filter canister was generated. Radiocesium is being removed from demineralizers A and B DA and DB by a process that was developed from laboratory tests on small samples of resin from the demineralizers.
The process was designed to elute the radiocesium from the demineralizer resins and then to resorb it onto the zeolite ion exchangers contained in the Submerged Demineralizer System SDS. It was also required to limit the maximum cesium activities in the resin eluates SDS feeds so that the radiation field surrounding the pipelines would not be excessive. The process consisted of 17 stages of batch elution. In the initial stage, the resin was contacted with 0. Results on the performance of the process in the cleanup of the demineralizers at TMI-2 are compared with those obtained from laboratory tests with small samples of the DA and DB resins.
To date, 15 stages of batch elution have been completed on the demineralizers at TMI-2, which resulted in the removal of about Ci of radiocesium from DA and about Ci from DB.
Catalog Record: Three Mile Island : a report to the | HathiTrust Digital Library
In the first few weeks after the accident, efforts centered upon regaining control and assessing the damage incurred. The early recovery work centered around the new systems required to supplement or replace damaged systems and components, and the new procedures needed to deal with the damaged plant.
To date, the TMI-2 recovery program has been successful in achieving:. Moreover, the program has proved to be a significant learning experience for the entire nuclear industry, which is enhancing the safety of nuclear plant operations. The TMI-2 accident has had a dramatic impact on the assessment of severe accidents, particularly on accident source term assumptions.
TMI not only demonstrated that regulatory interest in severe accidents is appropriate, but also illustrated our limited understanding of fission product behavior under degraded core conditions. The resulting reassessment of accident source terms has resulted in a concerted, world-wide research effort, which has produced a new source term estimation methodology. In order to assess the potential impact of the application of this methodology on regulatory requirements, a comparison with the approach used in licensing analyses is necessary. Such a comparison performed for the TMI-2 accident sequence, shows that differences in assumptions concerning accident progression far outweigh the differences in the methodology per se.
In particular, the degree of conservatism incorporated into assumptionsconcerning operator action and containment response has over-riding influence on source term estimates. A major contribution to the impact of the new source term methodology on regulatory requirements, therefore, is its capability to provide the improved level of understanding necessary for reassessment of regulatory assumptions in this area.
Japan quake: Nuclear lessons from Three Mile Island
Pair your accounts. Your Mendeley pairing has expired. Please reconnect. Toth 1 A. Malinauskas 2 G. Eidam 3 H. Burton 4. Publication Date Print : December 23, Joan Comstock i-vi DOI: First Page PDF. Description of the Accident Garry R. Thermal Hydraulic Features of the Accident B. Tolman C. Allison S. Behling S.
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Polkinghorne D. Taylor J. Exelon's Fein said the state-approved rate caps allowed the company to recoup investments that went to build power plants, but did not pay for new capital costs to comply with greater security measures imposed after the Sept. The place is a fortress. The main employee parking lots were relocated about yards from the plant entrance, separated by massive concrete barriers. The property is swarming with black-uniformed security personnel carrying military-style weapons, and bristles with guard towers, security gates, cameras, motion-detection devices, and steel ballistic barricades for delaying the advance of enemy combatants.
Many of the reactors slated for early retirement are single-unit plants, like Three Mile Island. Whether Pennsylvania legislators are willing to pay the extra cost for nuclear energy's attributes remains to be seen. Nearly 70 legislators signed on to an industry-inspired Nuclear Caucus this year, but legislative leaders have made no commitments.
At a time when the Trump administration is skeptical of the climate-change threat, it's unclear whether TMI's zero-emission credentials alone are sufficient to swing the debate in Harrisburg.
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Skip to content. Three Mile Island fights once again for its nuclear survival. Andrew Maykuth Maykuth amaykuth inquirer. Thomas P. Clem Murray.
The Inquirer Business Weekly Newsletter. Exelon Generation. Pictometry International. Exelon Generation of Kennett Square, which owns the surviving Unit 1, on the right, says it will retire the plant in unless the state comes to the rescue.
Mental health effects of the Three Mile Island nuclear reactor restart.
Clem Murray David Fein, an Exelon vice president for state government affairs. Never Miss a Story. We Recommend.