Research Needs for High-Level Waste Stored in Tanks and Bins at U.S. Department of Energy Sites Environmental Management Science Program (2001) / Chapter Skim
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3. Characterization
3. Characterization
Pages 28-36
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From page 28... ...
The main challenges in characterization consist of difficulties in retrieving and manipulating samples of radioactive material, with the related risk of radiation exposure to workers; high costs; long turnaround times; and poor data rel iabi I ity. Poor data reliability occurs when only a limited number of samples is available and these samples are not representative of the parameter measured.
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From page 29... ...
· Remote measurement: Determination of a material's characteristics from a distance without physical contact with the material. An example would be the determination of chemical composition by analysis of gamma radiation emitted after interrogation using neutrons from a remote source.
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From page 30... ...
Np, and Pu Residual radionuclides remaining in tanks and process facilities, such as Cs, Np,Tc, and Pu NOTE: RCRA = Resource Conservation and Recovery Act H I G H - L E V E L VV A s T E ~ A ~ 30
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From page 31... ...
These long turnaround times are due in part to administrative procedures. In practice, the operator must develop sampling plans, obtain radiation safety approval, and set up the equipment to retrieve the sample and send itto the laboratory.
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From page 32... ...
are maintained within a predetermined composition envelope before they are melted to ensure that the product is in compliance with the desired end waste form. Once the glass log is made, there is no provision for analytical verification of its acceptability or for recovery of the final glass waste form if its properties are unacceptable.
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From page 33... ...
However, characterization of the glass stream would confirm that the glass falls within the envelope of acceptable compositions and would determine whether species insoluble in the glass, such as crystalline spinels and noble metals, are trapped in the melter or are leaving with the glass product. Therefore, on-line characterization of the glass stream is a highly desirable process control option.
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From page 34... ...
Examples of characterization of equipment properties that influence the HLW cleanup process are the following: tank integrity; stress corrosion cracking and pitting of melter electrodes, valve boxes, and pipelines; and the level of obstruction and location of plugs in transfer lines. Currently, evaluation of the process vessels is carried out by manual inspection techniques, if at all.
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From page 35... ...
Because of the distance requirement, it will likely necessitate measu remeet of d ifferent properties th an wi I I on- I i ne, contact measu rements (see Sidebar 3.1~. However, remote monitoring would allow more analyses on waste prior to retrieval, providing real statistics on waste composition, reduced radiation exposure to workers, and quicker turnaround times.
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From page 36... ...
It is important to emphasize the need for developing long-term basic research for characterization purposes across the spectrum of the waste management process activities. Different DOE's focus areas involved in cleanup activities such as subsurface contamination and deactivation and decommissioning have similar characterization needs.
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