The Accident Three Mile Island

1
The Accident _at_Three Mile Island

(Names removed)
2
Overview

• Nuclear Power Station
• Middletown, Pennsylvania
• 28th March 1979
• 400 am

3
TMI Nuclear reactor
http//www.pbs.org/wgbh/amex/three/sfeature/images
/whatswhat.gif
4
Events . . .

• Slight malfunction in secondary loop
• Pressure and temperature rises in primary loop
• Backup pumps in the secondary loop automatically
  turns on
• Control rods are inserted into the core

5
Events Cont . . .

• PORV indicator light goes off
• EIW initiated water flows in to the primary loop
• Control Panel indicators show dangerously high
  water levels
• Operators take action

6
Events Cont . . .

• Discovery of closed valves
• Failure to detect radioactive discharge
• Water pumps in primary loop off
• Top of reactor core exposed

7
Events Cont . . .

• Control rods react with superheated steam
• PORV fault discovered
• Radiation Alarms triggered
• Operators lack trust in the system

8
Events Cont . . .

• PORV backup valve is opened to release pressure.
• Hydrogen Explosion!!!
• Operators regained control over core

9
The Clean Up . . .

• Cost
• Workforce
• Time scale
• Waste types

10
Real-Time Systems

• Safety critical system
• Control unit design
• Prioritisation of alarms
• Inadequate Training

11
Real-Time Systems Cont . . .

• Ethical considerations
• Liability

12
Implications

• Social
• Health

13
Summary . . .

• The accident at Three Mile Island was the cause
  of machinery malfunction which was made worse by
  human error.
• Three Mile Island Unit 2 was never re-opened, it
  will be decommissioned along side Unit 1 in 2014

14
References . . .

• Report of the Presidents Commission on The
  Accident At Three Mile Island, JG Kemeny
  (chairman), Pregaman Press, ISBN 0-08-025949-9.
• http//kd4dcy.net/tmi/multi media representation
  of events
• http//www.pbs.org/wgbh/amex/three/sfeature/images
  /whatswhat.gif(Multi media representation of
  events)

15
Questions

• Any questions?
• Thank you