Cost Based Failure Modes and Effects Analysis (FMEA) for Systems of Accelerator Magnets.

Abstract

The proposed Next Linear Collider (NLC) has a proposed 85% overall availability goal, the availability specifications for all its 7200 magnets and their 6167 power supplies are 97.5% each. Thus all of the electromagnets and their power supplies must be highly reliable or quickly repairable. Improved reliability or repairability comes at a higher cost. We have developed a set of analysis procedures for magnet designers to use as they decide how much effort to exert, i.e. how much money to spend, to improve the reliability of a particular style of magnet. We show these procedures being applied to a standard SLAC electromagnet design in order to make it reliable enough to meet the NLC availability specs. First, empirical data from SLAC's accelerator failure database plus design experience are used to calculate MTBF for failure modes identified through a FMEA. Availability for one particular magnet can be calculated. Next, labor and material costs to repair magnet failures are used in a Monte Carlo simulation to calculate the total cost of all failures over a 30-year lifetime. Opportunity costs are included. Engineers choose from amongst various designs by comparing lifecycle costs.

FMEA on the Superconducting Torus for the Jefferson Lab 12 GeV Accelerator Upgrade

“…The RPN is used as a measure of overall risk and helps to identify and rank the risks of the potential failure modes based on three criteria [5]- [7].…”

Comparison Study of Electromagnet and Permanent Magnet Systems for an Accelerator Using Cost-Based Failure Modes and Effects Analysis

“…There are 2 main methods to estimate the MTBF and MTTR of accelerator components, either one uses historical operating data of such devices or one takes failure rates from published failure data tables for the various parts of the device and adds them together. Previously we have used the SLAC accelerator failure database (CATER) to make predictions about the availability of all the electromagnets (em) and their PS in the 2001 configuration of the NLC [5]. However we have no operating data on adjustable permanent magnets (at SLAC or any other accelerator) and had to use a mixture of the two methods, and study devices with similar parts.…”

“…The values quantifying these various parameters are in the columns under "input" in Table II. The lifetime costs associated with each failure scenario, taking into account the frequencies, are calculated as explained in [5] and the median costs in US dollars are shown in the columns under "output" in Table II.…”

“…Does not sound so bad, but the lifetime cost to the project would be over $13.5 M! We use a Monte Carlo simulation with triangular distributions for some input parameters to estimate the possible range of failure costs [5]. We simulated the design, fabrication and installation stages plus 30 years of operations of an NLC em system and a hybrid system, 5000 times each, to find the distributions of lifecycle failure costs.…”

Identify, analyse and mitigate—Quantification of technical risks in PV power systems

“…There are several interpretations of the concept of risk, but in general, risk can be defined as the probability of failure multiplied by the consequences of its failure. The common approach in evaluating technical risks is to apply a classical failure mode and effects analysis (FMEA) 1 . It is widely used in the automotive, aerospace and electronics industries to identify, rank and mitigate potential failures.…”