External screening process

This appendix presents the potential external events that are considered in the hazard analysis of the Hot Cell Facility (HCF) and its associated radioactive material storage facilities. From this list of events, a screening assessment was performed to eliminate from further consideration any of e events that posed little or no hazard to the HCF and associated radioactive material storage facilities or their contents. Events that were not eliminated in this screening process were to be analyzed more closely as part of the qualitative analyses contained in Appendix 3C or 3D (and are summarized in Section 3.3.2, Hazard Analysis Results ). 

Potential external events were identified by reviewing previous Safety Analysis Reports of similar DOE facilities (Restrepo 1995) and the recommended list of external events used to evaluate commercial nuclear power plant risks (NRC 1983). In addition, an attempt was made to identify any other potential external-initiating event unique to the site that had not been considered in previous studies. It is important to note that operational accidents (e.g., criticality, internal fires) occurring inside the HCF and assodated radioactive material storage facilities are not considered in this screening process. These types of "internal initiating events are identified separately using preliminary hazard checklists (see Appendix 3A). 

All of the events listed in Table 3B-1 were eliminated from further consideration by using this screening process. (Some events were eliminated based on multiple criteria.) This does not mean they are all eliminated from all further consideration in the HCF SAR. Some external events are considered in Appendix 3C, Preliminary Hazard Analysis," or Appendix 3D, Failure Modes and Effects Analysis," as potential initiators to internal hazard events. 

These strong effects of external screening are well described by the Hartree-Fock model. In the Hartree approximation, the spherical average of the repulsion from the other (K - 1) electrons is subtracted from the potential Z/r (in the atomic units of hartree/bohr) originating in the nucleus considered as a point, and the Schrodinger equation is solved for radial n/-functions in this central field U(r). This needs an iterative process in order to obtain self-consistency between radial func-... 

The screening process can then consider the potential for off-site and onsite consequences induced by the external event. Table 8 presents possible consequences of external events to be analysed for screening. 

The three signals are fed into an oscilloscope as vertical-, horizontal-, and external-intensity marker input. The keyphazor appears as a bright spot on the screen. In cases where the orbit obtained is completely circular, the maximum amplitude of vibration occurs in the direction of the keyphazor. To estimate the magnitude of the correction mass, a trial-and-error process is initiated. With the rotor perfectly balanced, the orbit finally shrinks to a... 

Cost estimation and screening external MSAs To determine which external MSA should be used to remove this load, it is necessary to determine the supply and target compositions as well as unit cost data for each MSA. Towards this end, one ought to consider the various processes undergone by each MSA. For instance, activated carbon, S3, has an equilibrium relation (adsorption isotherm) for adsorbing phenol that is linear up to a lean-phase mass fraction of 0.11, after which activated carbon is quickly saturated and the adsorption isotherm levels off. Hence, JC3 is taken as 0.11. It is also necessary to check the thermodynamic feasibility of this composition. Equation (3.5a) can be used to calculate the corresponding... 

So far, an MOC solution has been identified through a two-stage process. First, the use of process MSAs is maximized by constructing the pinch diagram with the lean composite stream composed of process MSAs only. In the second stage, the external MSAs are screened to remove the remaining load at minimum cost. 

Three major sources in the kraft process are responsible for the majority of the H2S emissions. These involve the gaseous waste streams leaving the recovery furnace, the evaporator and the air stripper, respectively denoted by R), R2 and R3. Stream data for the gaseous wastes are summarized in Table 8.8. Several candidate MSAs are screened. These include three process MSAs and three external MSAs. The process MSAs are the white, the green and the black liquors (referred to as Si, S2 and S3, respectively). The external MSAs include diethanolamine (DBA), S4. activated carbon, Sj, and 30 wt% hot potassium carbonate solution, S6. Stream data for the MSAs is summarized in Table 8.9. Syndiesize a MOC REAMEN that can accomplish the desulfurization task for the three waste streams. 

Classification Using Pre-Established Limiting Concentrations and Enhanced Access. The same process as in the previous calculation was used to screen this example waste under conditions where intruder access to the waste would be enhanced. For example, if the cover for the waste is less than 2 m, it would be appropriate to consider that an intruder would remove sufficient cover material to expose the waste. The maximum allowable concentrations of selected radionuclides for this scenario calculated using the RESRAD code are listed in Table 7.3. The analysis assumes that the intruder is exposed via external exposure, ingestion, and inhalation for a period of 1,000 h. Using the sum of the ratios of the radionuclide concentrations in the waste to the maximum allowable concentrations as a... 

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