Radioactive waste disposal rates

Table 1. Sedimentation Rates and Curve Fitting of 210Pb Measurements in Cores Collected at the U. S. Radioactive Waste Disposal Sites Near the Farallon Islands 60 km off San Francisco and at the Hudson Canyon, 350 km off New York City.

Halford, D.K., O.D. Markham, and G.C. White. 1983. Biological elimination rates of radioisotopes by mallards contaminated at a liquid radioactive waste disposal area. Health Phys. 45 745-756. 

The 1325-N LWDF, shown in Figure 3-20, started receiving part of the N Reactor liquid radioactive effluent in 1985. In September 1985, the 1325-N LWDF became the primary liquid radioactive waste disposal facility for the N Reactor. The nominal effluent flow rate during reactor operation was 6,345 L/min (1,700 gal/min) and is now less than 7.5 L/min (2 gal/min). 

N-1 1301-N Liquid radioactive waste disposal system for N Reactor. Effluents from reactor coolant system, spent fuel storage basin, periphery coolant systems, and various radioactiv e drain systems in the reactor facility. Also disposal area for various laboratory chemicals. Historical average high flow rate of 2.100 gal/min. Crib and trench. 

Release rate data from actual radioactive waste forms is needed to evaluate the safety of emplacing nuclear wastes in geologic media. However, in addition to waste form development studies, such as the leach test just described, a comprehensive program was started to obtain release data from candidate waste forms for geologic disposal. 

Waste form leach rates in a geologic repository will be affected by unknown water flow rates and by extensive cracking of the waste form monolith. An understanding of these effects is important in predicting the geochemical behavior of disposed radioactive waste forms over the full range of possible scenarios. The dependence of the waste form source term on the rate of renewal of aqueous solution is first established for the simple but important case of solubility-limited network dissolution control. 

The Agl-cement exhibited the best leach resistance of all forms tested. Figure 1 presents the results for the static and dynamic leach tests of Agl cements. The leach rate unit of cm/d may be converted to fraction leached per day by multiplying by the surface area-to-volume ratio. Using the data presented in Figure 1 for the dynamic leach test between days 40 and 100 and assuming a linear extrapolation, over 4000 years are required to leach 1% of the iodine from a 208 L (55 gal) cement monolith. A 208 L steel drum is the typical waste container used for disposal of low activity radioactive waste and is used in this report as the standard waste package. 

A radioactive nucleus which emits a particle to become transformed to another nucleus is described as decaying to that nucleus. Such a radioactive event is called radioactive decay. Radionuclides decay at different rates. Some can decay in millionths of a second, others take millions of years. Decay is independent of all the variables which affect chemical reactions such as temperature, pressure, and concentration. This poses particular difficulty with regard to the disposal of nuclear wastes. The rate of radioactive decay is characterized by the loss of a constant percent per unit time, not a constant number of moles per unit time. We therefore characterize the decay rate by specifying the time required for 50 percent of the original material to decay. This period of time is called the half-life, given the symbol, tj/j- The constant percent change means that 50 percent will be lost during the first half-life, 50 percent of what is left after the first half-life will decay over the second half-life, etc. 

Certain waste treatments reduce multiple hazards in one step. For example, incineration can destroy oxidizable organic chemicals and infectious agents, waste feed rates can be controlled to meet emission limits for volatile radionuclides, and radioactive ash can be disposed of as a dry radioactive waste. Likewise, some chemical treatment methods (e.g., those using bleach) both oxidize toxic chemicals and disinfect biological hazards. Such treatment could convert a chemical-radioactive-biological waste to a radioactive waste. 

Highlights. Treatment of the radioactive waste from nuclear reactors is one of the points that receive wide public attention and the disposal and burial of HLW in particular is a contentious issue due to the concerns about leakage to the environment. The technical solutions that are currently used to treat the waste that were listed earlier (concentrate-and-contain, dilute-and-disperse, and delay-and-decay) are not suitable for HLW, where safer solutions like vitrification or Synroc are sought. The characterization of the LLW and MLW waste is not as complicated as that of spent fuel but stiU greatly more complex than analysis of fresh fuel. Some of the procedures and methods used in other parts of the NFC are suitable for LLW and MLW. The composition of HLW must be determined in order to estimate the decay rate of the radioactivity and to classify the required protective measures that depend on the radionuclides and their products (emitters of alpha, beta, gamma, and neutrons). 

II-ll. Disposable clothing may be relatively costly when the rate of usage is high, and it contributes to the volume of solid radioactive waste material that must be processed. It is appropriate, however, to use disposable clothing when laundering becomes impracticable owing to high levels of contamination. 

When disposing of radioactive waste, the multiple barrier system must give assurance that any release of radioactive material to the environment is restricted to an acceptably low rate. The resulting additional radiation dose to the population shall not exceed a low limit corresponding to a small fraction of the dose from natural background radiation. 

Performance of the unit has proven to be dependent on the level of decontamination required and on the type of coating covering the decontamination. An evaluation of the technology noted that the reliability of the equipment was low and that the system had a low production rate. Wastes recovered by this process may require additional treatment or disposal as radioactive, mixed, or hazardous wastes. 

Process pH, sodium, calcium, and nitrate concentrations, plugging of the ion exchange column, lot variance, and the presence of binders can affect process efficiency. lonsiv IE-911 does not remove anionic radioactive ions such as technetium. The resins are designed for one-time use and must be replaced when loaded. The waste acceptance criteria at the resin disposal facility may limit the loading of the CST resin. Size constraints of the cesium removal system (CRS) may limit system flow rates. 

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