Nonelectronic Parts Reliability Data 1991

An analysis of the annual probability of failure of the waste hoist brake system at the Waste Isolation Pilot Plant (WIPP)

“…The NPRD data are revised and updated periodically. WEC-WID (1994) used data from NPFUl-91 (Denson et al, 1991). NPRD-95 (Denson et al, 1994) was published a few months after the publication of WEC-WID (1994), but fortunately only a few relatively small changes occurred in components relevant for the report.…”

“…WEC-WID (1994) used data from NPFUl-91 (Denson et al, 1991). NPRD-95 (Denson et al, 1994) was published a few months after the publication of WEC-WID (1994), but fortunately only a few relatively small changes occurred in components relevant for the report. An advantage of the NPRD series is that the information is listed not only in terms of a failure rate of a generic part, but also in terms of the environment in which the part is used.…”

“…In the revised design (WEC-WID, 1994), realistic failure data from NPRD-91 (Denson et al, 1991) for certain critical valves were used which were an order of magnitude or more higher than the values used for the Design Option B-2 described in the earlier DOE reports. Despite this, the final calculated value of the annual failure rate for the brake system in the revised design is given as approximately 1.3 (E-7) (Uyr), only slightly better than the 2.2 (E-7) (Uyr) for Design Option B-2.…”

“…This is in accord with standard engineering practice. Calculations were made for the data from NPRD-95 (Denson et al, 1994) and also from NPRD-91 (Denson et al, 1991) Le. there is a 98.2% likelihood that the failure rate is less than 1.0 x loa.…”

“…They used NPRD-91 (Denson et al, 1991) published in May, 1991. This was the latest NPRD publication available to WEC-WID (1994), which appeared in February, 1994.…”