agenda background update on fukushima daini update on fukushima dai-ichi – summary of events at...

Agenda

• Background• Update on Fukushima Daini• Update on Fukushima Dai-ichi– Summary of Events at Fukushima Dai-ichi

• Summary of Radiation and Reports

Boiling Water Reactors (BWRs)

Fukushima Daini

• Units 1, 2, and 3 are in cold shutdown status– Pressure is near atmospheric– Temperature is below 100°C

• Unit 4 is still being actively cooled– No signs of trouble

Fukushima Dai-ishi

• Unit 1: 460 MW, 1967• Unit 2: 784 MW, 1969• Unit 3: 784 MW, 1970• Unit 4: Shutdown, unfueled. 11/10• Unit 5: Shutdown, fueled. 1/11• Unit 6: Shutdown, fueled. 8/10

Fukushima Dai-ichi Unit 1

• SCRAM – immediate shutdown following the earthquake

• External power was lost• Diesel generators started backup cooling• Diesels failed due to tsunami damage• Reactor Core Isolation Cooling (RCIC) pumps

continued to operate on steam from the reactor• Batteries drained, losing power to valves• Complete blackout

• Primary water was lost and core degradation occurred

• Zirc alloy oxidizes, resulting in hydrogen formation

Fukushima Dai-ichi Unit 1

• Portable diesel generators are delivered, backup pumps replace water to the Reactor Pressure Vessel

• Pressure in containment drywell rose as wetwell became hotter

Fukushima Dai-ichi Unit 1

• Pressure was relieved to the reactor building, gasses included hydrogen produced from zirconium oxidation

• Hydrogen in the reactor building exploded, causing the collapse around the containment.

Fukushima Dai-ichi Unit 1

• Began injecting seawater into the vessel to continue the cooling process

• Similar events happened at Units 2 and 3

Fukushima Dai-ichi Unit 1

Fukushima Dai-ichi Unit 2

• An explosion at Unit 2 may have damaged the suppression pool

• A fire at the Unit 4 fuel pool has led to a radiation release– The fire is extinguished

and radiation levels are decreasing steadily

Radiation Levels

• REM (Radiation Equivalent Man)• 100 REM = 1 Sievert

• Normal, Background• Comic, Terrestrial

• Medical– Chest X-Ray: 10 mREM– Abdominal CT: 2000 mREM

Average Dose in U.S.: 620 mREM/year

51%

37%

5% 5%

2%Sources of Radiation

Medical

Rocks, Soil, and Radon

Cosmic

Human Body

Consumer Products

Radiation Reports

• 8 times normal:– 0.059 mREM/hr

• 1000 times normal:– 7 mREM/hr

• Maximum levels– On site: 40 REM/hr– Boundary: 1.2 REM/hr– Dose: 10.6 REM

Acute Radiation Sickness

• Whole Body < 100 REMs– 25 REMs:

• Possible changes in blood cells

– 50 REMs:• Consistent changes in blood cells• Decrease in size of lymph glands

– 80 REMs:• 50% chance of temporary

sterility in males

• 100 – 200 REMs– Symptoms begin at 100 REMs

and become common (50% chance) at 200 REMs

– Mild to moderate nausea– Occasional vomiting (3-6 hrs)– Loss of appetite– fatigue

Radiation Check

Last Thoughts

• Our thoughts and prayers go to those who have lost their lives and livelihood in this disaster.

• We wish the best for those still working at the plants. They are our first responders. They are heroes.

Nuclear Fission

Future of Nuclear Power