Tutorial 6: Case Study

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Tutorial 6Case Study

• Peppermint Twist
• Genie in the Bottle
• SY DE 142 July 5, 2003
• Introduction to Human Systems Engineering
• Waterloo, Ontario, Canada

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Outline

• Case 1 Peppermint Twist
• Question and Discussion on Case 1
• Case 2 Genie in the Bottle
• Questions and Discussion on Case 2

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The Peppermint Twist

• Place Trendy nightclub , Topeka
• Time September 1989
• Results
• Dishwashing fluid, indistinguishable from
  watermelon-flavored mixed drink, poisoned girl
  and several others at the night club

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The Peppermint Twist Question

• In this case, several solutions were possible.
  One could have improved the situation by
• A) making the detergent less poisonous
• B) locating the dishwasher farther from
  the bar.
• Explain how these solutions would have changed
  system characteristics that created the accident.
  
• Hint Look at Lecture 2 on System Accidents

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The Peppermint Twist Solution

• Making the detergent less poisonous
• makes the system less tightly coupled
• Locating the dishwasher further away
• increases the distance between dishwasher
  and drinks. This minimized proximity interactions.

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Case Study 2Genie in the Bottle

• Time January 3, 1961
• Place National Reactor Testing Station,
  Idaho
• Synopsis Maintenance crew removed a high-worth
  control rod from a nuclear reactor causing a
  nuclear accident.

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Genie in the Bottle Questions

• 1. Explain what kind of error this was and
• why.
• 2. What would have been the best way to prevent
  this error?
• 3. Give an example of how to do this in the Genie
  case.

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Genie in the Bottle Solutions

• The crew made a mistake because the actions
  (raising the rod higher) they took were correct
  given their intention.
• Also they did not understand the type of
  control rod and the workings of the reactor, they
  operated with the wrong intention (to raise the
  rod higher) making this a mistake.
• Mistake (wrong intention right action)

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Genie in the Bottle more Solutions

• 2. This error could have been prevented
• through the use of a forcing function.
• A forcing function is the best way because it
  does not require training or manuals and
  physically makes it impossible for the rods to be
  removed.
• 3. An example of this
• would have been a physical barrier which
  would have prevented the workers from removing
  the rod too far.