Accidents evaluation

Hazards analysis techniques fall in two broad categories. Some techniques focus on hazards control by assuring that the design is in compliance with a pre-existing standard practice. These techniques result from prior hazards analysis, industry standards and recommended practices, results of incident and accident evaluations or similar facilities. Other techniques are predictive in that they can be applied to new situations where such pre-existing standard practices do not exist. 

Lee, J.H., Knystautas, R., Chan, C., Barr, P.K., Grcar, J.F., Ashurst, W.T. "Turbulent Flame Acceleration Mechanisms and Computer Modeling", International Meeting on High-Water Reactor Severe Accident Evaluation, Cambridge, Mass., Aug. 28 -Sept. 1 (1983), also appeared as Sandia Report SAND 83-8655. 

The post-processing In the post-processing, influencing factors mainly include dealing with the aftermath, investigation, and the accident evaluation summarizing. 

Accident evaluations specific to the GT-MHR confirmed that the passive safety characteristics of the previous steam cycle modular high temperature gas-cooled reactor designs were maintained. Events initiated by one or more turbine blade failures were assessed. It was found that the resulting differential pressure forces across the prismatic core did not exceed the allowable graphite stresses. Since the dominant risk contributor for the steam cycle design were initiated by water ingress from the steam generators, the GT-MHR is expected to have a lower risk profile to the public. References 4 and 5 provide more information on the GT-MHR safety evaluations. 

Planning for emergency preparedness is based on the analyses of potential HCF accidents evaluated in this SAR are presented in Chapter 3. No credible HCF accidents are postulated to pose significant hazards to other TA-V personnel, off-site personnel, the general public, or the environment, and only a few of those analyzed result in localized radiological consequences to personnel and facilities. 

The AP600 design has been confirmed by the results of transient and accident analysis to meet its safety objectives. Core melt down frequency and severe accident evaluation show that the passive systems are effective in mitigating the consequences of design basis accidents. 

Basic safety studies and accident evaluation. Part of Preliminary Safety Analysis Report First cost estimates Marketing file... 

The accident evaluation assumed all the available space within the unit to be occupied by a homogeneous mixture of UO2 and water with the maximum enrichment of 4.0 wt% in U. A uranium density of 2.4 gU/cm was used because it resulted in the highest K-effective... 

Cronenberg, A. W., Appelhans, A. D., MacDonald, R E., Rest, J., Lorenz, R. A. An assessment of liquefaction-induced I, Cs, and Te release from low and high bumup fuel. Proc. Intemat. Meeting on Light Water Reactor Severe Accident Evaluation, Cambridge, Mass., USA, 1983, Paper 4.5... 

Proceedings of the International Meeting on LWR Severe Accident Evaluation, Cambridge, MA, 1983. 

A fault tree analysis is not only an ideal method of hazard identification, but also of analyzing the risks contained in a process or a plant. The fault tree analysis encourages objective thinking and is effective in tracing possible causes of accidents, evaluating possible equipment failure, which leads to the prediction of an accident. 

Chemical plants—Accidents-Evaluation 2. Risk assessment. 

The accident in a PFR superheater unit, a power plant of similar size to SNR-300 but of pool design resulted in breach of 40 bundle tubes. A larger number were damaged to a certain extent, as post-accident evaluations revealed. The containment boundary of the intermediate heat exchanger, however, was not affected. Subsequent calculations showed that there was a sufficient safety margin, so that nuclear safety was not impaired. 

In the absence of detailed information about the accident, its origin and course had to be reconstructed and derived from post-accident evaluations. Both could be put down to the choice of material, specific design features of the apparatus, and to incomplete monitoring of important operational parameters. 

Tiravanti, G., Rozzi, A., Dall Aglio, M., Delaney, W., Dadone, A., The Cavtat Accident Evaluation of Alkyl Lead Pollution by Simulation and Analytical Studies, Prog. Water Technol. 12 [1980] 49/65. 

V. E. Denny and B. R. Sehgal, "Analytic Prediction of Core Heatup Liquefaction/Slumping," (Proc. Int. Mtg. on LWR Severe Accident Evaluation. Cambridge, MA, p5.4-l, 1983. 

Section 2.1 provided a discussion of design-basis accidents, as included in Chapter 15 of the Safety Analysis Report (SAR). For containments, the design must preclude exceedance of the 10 CFR 100 dose guidelines, given the most limiting accident evaluated in Chapter 15. Specifically, the requirements of 10 CFR 50, Appendix A, General Design Criterion 50 state ... 

Proceedings, International Meeting on Light Water Reactor Severe Accident Evaluation, August 28-September 1,1983, Cambridge, Massachusetts... 

If you find that the air quality contributed to the accident, evaluate the cmrent engineering or administrative controls to see if the air quality can be improved. If it cannot be improved, ensure that proper PPE is being used. You may also want to investigate the arnormt of exposure employees were subjected to in the accident area to ensure that they were not exposed above the permissible exposure limits (PELs). 

Now that you have determined the root cause(s) of the accident, evaluate it/them to determine how the cause can be prevented from occurring in the future. With the help of other supervisors, managers, and employees, discuss quantitative ways to remove the root cause(s) from the system. As explained at the beginning of Step 8, ensure that you are evaluating and discussing root causes, and not symptoms. 

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