Failure containment

RMDB is supplemented by microfilmed reports containing failure rates/modes and analyzed data. Reports relating to the theory and procedural techniques to obtain and analyze reliability-maintainability data are cataloged, abstracted, microfilmed and computer listed in the R-M Data Summaries. 

IEEE Std 500-1984 (IEEE, 1984) contains failure rate and out of service, repair and restoration times for electrical electronic, and sensing component, and mechanical equipment. It is a considerable improvement over IEEE STD 500-1977. The reported values are the consensus of over 200 experts. Each expert submitted a low, recommended, and a high value for the failure rate... 

Equipment Failures Safety system Ignition Sources Furnaces, Flares, Incinerators, Vehicles, Electrical switches. Static electricity, Hot surfaces. Cigarettes Human Failures Omission, Commission, Fault diagnosis. Decisions Domino Effects Other containment failures. Other material release External Conditions Meteorology, Visibility... 

The assumed form of iodine is not substantially retained in early containment failure, but may be retained in the reactor coolant system, where cesium iodide is more strongly retained than the elemental iodine assumed by the RSS. 

The final three phenomena, items 11 through 13, are addressed in the containment performance models of MARCH, accounting for mass and energy additions to the containment, the burning of combustible gases, the effects of core sprays, ice condensers, and suppression pools. MARCH calculates only the containment loads it does not model the containment failure. 

It has also been shown that heat radiation may heat and weaken the containment. The failure of penetration seals due to high temperature has been investigated, but full scale containment failure test have not been done. 

Core damage and containment performance was assessed for accident sequences, component failure, human error, and containment failure modes relative to the design and operational characteristics of the various reactor and containment types. The IPEs were compared to standards for quality probabilistic risk assessment. Methods, data, boundary conditions, and assumptions are considered to understand the differences and similarities observed. 

Fig. 11.1.-2 Conditional Containment Failure Probabilities from the IPEs...

Theofanous, T. G, et al., The Probability of Mark I Containment Failure by Meli-Aitack... 

Answer Use the plant s PSA to determine the risk of accidents that include containment failure from overpressurization. Then make a preliminary design of a vented containment that has sufficiently low impedance to the gas at the pressure predicted for the most severe accident sequences such that the containment is not damaged. This containment bypass will include iodine and HEPA filters as well as scrubbers and a discharge through a stack. Estimate the dose that the population would get using this bypass for comparison with the PSA result for ruptured containment sequences. 

A BLEVE s effects will be determined by the condition of the container s contents and of its walls at the moment of container failure. These conditions also relate to the cause of container failure, which may be... 

In the present context, the term BLEVE is used for any sudden loss of containment of a liquid above its normal boiling point at the moment of its failure. It can be accompanied by vessel fragmentation and, if a flammable liquid is involved, fireball, flash fire, or vapor cloud explosion. The vapor cloud explosion and flash fire may arise if container failure is not due to fire impingement. The calculation of effects from these kinds of vapor cloud explosions is treated in Sections 4.3.3 and 5.2. 

The Database contains failure rate data for most major equipment Items that are found throughout the process industhes... 

The data base contains failure rate data plus some failure mode information for process equipment - pumps, compressors, gas turbines, valves, vessels, heat exchangers etc. 

DATA BOUNDARY The data base contains failure rate data plus some failure... 

System Reliability Service Varied Status reports contain failure, repair, and maintenance data on 450 categories data sets are broader A wide variety of equipment failure and performance records from utilities and manufacturers, plus collected inspection data 75. 

The German Gesellschaft fur Reaktorsicherheit (GRS) has a private arrangement with Rheinische Westalisches Elekrizitatswerke (RWE) to compile reliability data from an operating power plant, Biblis B. The data base contains failure rate, maintenance, and operational event data. External event data (floods, earthquake, fire, etc.) are compiled through a separate utility-sponsored data base. The data base provides information on repair and maintenance, and equipment performance. 

NUMBER AND TYPE OF RECORDS Status reports contain failure, repair, and... 

NUMBER AND TYPE OF RECORDS Over 100 data sheets, containing failure... 

The part stress analysis prediction section contains failure rate models for a broad variety of parts used in electronic equipment. This method includes the effects of part quality factors and environmental factors. The tabulated values of the base failure rate are "cut off" at the design temperature and stress of the part. 

Pressure Vessel Failure Statistics and Probabilities Nuclear 4 tables containing failure data for vessels Primarily concerned with boiler failures 113. 

Appendix III contains failure rate estimates for various genetic types of mechanical and electrical equipment. Included ate listings of failure rates with range estimates for specified component failure modes, demand probabilities, and times to maintain repair. It also contains some discussion on such special topics as human errors, aircraft crash probabilities, loss of electric power, and pipe breaks. Appendix III contains a great deal of general information of use to analysts on the methodology of data assessment for PRA. 

Section 5.5 presents a data sheet for each cell in the taxonomy that contains failure rate data. Empty data cells are not presented. Filled data cells are listed by their CCPS Taxonomy number in Table 5.2 as an aid to the user. The CCPS data sheet format was developed from a number of sources including OREDA and IEEE Std. 500-1984. The format is presented in Figure 5.3, and its data elements are explained below ... 

As explained in Section 3.3, failure rate data for a piece of equipment or system can be located by the taxonomy number for the equipment. The number can be found by using the CCPS Taxonomy, Appendix A, or the alphabetized hardware list in the Equipment Index, Appendix B. Table 5.2 shows whether the CCPS data base contains failure rate data for that numbered data cell or for an appropriate higher-level cell. Alternatively, the user may look directly for the desired taxonomy cell in the data tables. 

Assessments of the comparative safety of the different modes of transport should take into account both die risk to die public and die risk to terminal operators and tnuisport crew. The transporter may be imohed in a crash or denuhnent drivers may be injured or killed. Thus, die events that can give rise to liazards include container failure, loading and unloading operations, and accident impact. Hazardous materials are moved by ... 

Electrostatics enters into the problem of secondary explosions in several ways. First, an electrostatic spark may be the ignition source of the primary explosion. Second, an electrostatic spark can serve to ignite a dust cloud if particulate spews out at high velocity as a result of a sudden piping or vessel containment failure. Similar containment failures have occurred with insulating liquids and can not be ruled out for powders. For example,... 

To reduce the risk of container failure, the pressure vessels are equipped with several safety features. These can include an effective self-venting system where unforeseen overpressure is released by a quick open-resealing step, or the use of safety disks which rupture when their pressure limit is reached. The small vials (0.2-20 mL) of some monomode reactors are protected by the pressure limit (20 bar) of the caps used, which is significantly lower than the operating limit of the vials themselves (40-50 bar). 

Finally, the entire fault tree procedure enables the application of computers. Software is available for graphically constructing fault trees, determining the minimal cut sets, and calculating failure probabilities. Reference libraries containing failure probabilities for various types of process equipment can also be included. 

II. Containment failure under design operating conditions due to imperfections in the equipment... 

---