Degradation, fail-safe

Fail-safe Landfill The concept of the sustainable landfill is echoed in the philosphy of fail-safe landfill (Loxham, 1993). The fail-safe philosophy argues that whatever the containment system utilised, it will ultimately fail and/or institutional control will cease, and the contents within e.g., leachate, will be released to the environment. It therefore requires that any releases should be such that the risk posed to the environment is acceptable. For this to be the case, waste disposed to landfill must be pre-treated or degradation must be accelerated such that the hazardous nature of Ae waste and waste products are minimised. 

In state 3 one imit has failed in a safe undetected manner. In this condition the system has also degraded to loolD operation. Additional safe failures or dangerous detected failures will cause the system to fail safely. An additional dangerous undetected failure will fail the system dangerously taking the Markov model to state 6 where both units have an undetected failure. Failures from this state are not detected until there is a maintenance inspection. 

A problem common to electrochemical cells is the analyzer can fail (degradation of the anode material and electrolyte or loss of sensor sensitivity), but still indicate a safe oxidant level when in reality it may not be so. Adherence to the manufacturer s recommendation as to how... 

In state 1 the system has degraded to loolD operation. A second safe failure or a dangerous detected failure will fail the system safely. Like the loolD, a dangerous undetected failure will fail the system dangerously. In... 

In case of any safety-related absolute or Sequent lime constraints, at least a safety-related time monitor needs to be implemented. This lime monitor could be used to trigger a watchdog so that the system could be degraded in a safe state by a consoller shut-down. If a shut-down of the controller isn t the safe state, for example in fail-operational systems such degradations don t provide any safe reactions. 

Two or more individual redundant components fail or are degraded such that they cannot be used when needed, or used safely if still operational... 

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