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Monitoring radiation levels in the Pacific Northwest The Fukushima Nuclear Crisis:Separating Fact from Fiction Simon Fraser University April 11, 2011 Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 1 / 22

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Page 1: SFU Radiation Presentation

Monitoring radiation levels in the Pacific Northwest

The Fukushima Nuclear Crisis:Separating Fact from Fiction

Simon Fraser University

April 11, 2011

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 1 / 22

Page 2: SFU Radiation Presentation

The nuclei

The nuclear chartN

um

ber

of

pro

ton

s Z

Number of neutrons N

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 2 / 22

Page 3: SFU Radiation Presentation

Nuclear decay

Nuclear decay half-life

T1/2 T1/2T1/2 T1/2

8 days

30 years

24100 years

0 1 2 3 4

Pu

Cs

I131

137

239

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 3 / 22

Page 4: SFU Radiation Presentation

Nuclear fission

Nuclear fission

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 4 / 22

Page 5: SFU Radiation Presentation

Nuclear fission

Fission fragmentsN

um

ber

of

pro

ton

s Z

Number of neutrons N

U235

Pu239

238U

232Th

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 5 / 22

Page 6: SFU Radiation Presentation

Nuclear fission

The nuclear chartN

um

ber

of

pro

ton

s Z

Number of neutrons N

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 6 / 22

Page 7: SFU Radiation Presentation

Fuel release

Fresh and spent nuclear fuel

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 7 / 22

Page 8: SFU Radiation Presentation

Fuel release

Nuclear chain reaction

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 8 / 22

Page 9: SFU Radiation Presentation

Fuel release

Plutonium

Plutonium (Pu) is a man made, radioactive, heavy element containing94 protons.

239Pu is produced in fuel containing 238U.

239Pu is the material of choice for nuclear weapons.

Mixed Oxide nuclear fuel used in one of the Fukushima reactorscontains Pu/U mixture.

The element of Pu is highly toxic when inhaled, (less toxic wheningested).

Animal studies found that an accumulated dose of a few milligram ofplutonium per kilogram of tissue is lethal.

Traces of Pu were reported to be found at the Fukushima site (but nottalked about recently).

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 9 / 22

Page 10: SFU Radiation Presentation

Fission fragments release

Radio-iodine 131I

131I is a man made radioactive isotope of Iodine.

131I has a half life of 8 days.

131I is an abundant fission fragment.

131I is used in radiotherapy of cancer.

131I is not found in the atmosphere in normal conditions .

131I is a good indicator of radioactivity release in reactor accidents,the signal is not obstructed by background.

Iodine accumulates in the thyroid, thus large scale exposure to 131I isa potential health hazard.

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 10 / 22

Page 11: SFU Radiation Presentation

Fission fragments release

Radioactive 137Cs

137Cs is a man made radioactive isotope of Cesium.

137Cs has a half life of 30 years.

137Cs is an abundant fission fragment.

137Cs is used in radiotherapy of cancer and in food irradiation.

137Cs was not present in the environment before 1940’s when fissionstarted to be used for nuclear power releases.

137Cs background from nuclear weapon tests and previous nuclearaccidents obscures the signal from Fukushima.

Contamination with 137Cs is long lasting.

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 11 / 22

Page 12: SFU Radiation Presentation

Fission fragments release

Nuclear weapon tests

∼2000 reported tests ∼550 atmospheric explosions

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 12 / 22

Page 13: SFU Radiation Presentation

Fission fragments release

Fission fragments release

Release depends critically on the accident scenario.

Fission fragments which exists as gases, vapours, or aerosols arereleased first.

The Three Mile Island accident released gases only, including 131I.

The explosions and fires following the Chernobyl accident resulted ina release of 6 tons of fragmented fuel along with radioactive gases.

The release of 131I from the Chernobyl was 2.4 million times largerthan from the Three Mile Island accident.

The crisis management at Fukushima successfully preventedlarge-scale radioactivity release in the past month, however, thecooling operates under emergency conditions.

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 13 / 22

Page 14: SFU Radiation Presentation

Radiation detection

Characteristic decay spectra

Blue: 137Cs Red:60Co

200 600 1000 1400 1800Energy [arb.]

2

5

10

20

50

100

200

500

1000

2000

Cou

nts

per

Cha

nnel

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 14 / 22

Page 15: SFU Radiation Presentation

Radiation detection

GEARS: Germanium detectorfor Elemental Analysis and Radioactivity Studies

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 15 / 22

Page 16: SFU Radiation Presentation

Radiation detection

Background suppression

Blue: shielded Red: unshielded

200 600 1000 1400 1800 2200 2600Energy (keV)

10 1

10 2

10 3

10 4

Cou

nts

per

Cha

nnel

1460

1764 26

11

2444

2202

2103

1847

511

60935

229

323

618

2

1121

1237

1376

970

911

728

1726

1508

91

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 16 / 22

Page 17: SFU Radiation Presentation

Monitoring of Fukushima releases

131I signature in the SFU rainwater

50

150

250

Cou

nts

50

150

250

Cou

nts

340 380 420 460 500 540Energy [keV]

50

150

250

Cou

nts

365

352 51

1

365

352 51

1

365

352 51

1

March 18

March 20

March 29

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 17 / 22

Page 18: SFU Radiation Presentation

Monitoring of Fukushima releases

Time profile of the 131I signature in Burnaby rainwater

Date03/11 03/18 03/25 04/01 04/08

Sp

ecif

ic a

ctiv

ity

[Bq

/l]

0

2

4

6

8

10

12

14

16

I in Burnaby rainwater131Specific activity of

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 18 / 22

Page 19: SFU Radiation Presentation

Monitoring of Fukushima releases

131I sampling in seaweed

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 19 / 22

Page 20: SFU Radiation Presentation

Monitoring of Fukushima releases

131I signature in the North Vancouver seaweed

Blue: March 15 Red: March 22

340 380 420 460 500 540Energy [keV]

50

150

250

Cou

nts

50

150

250

Cou

nts

365

352

511

352

511

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 20 / 22

Page 21: SFU Radiation Presentation

Monitoring of Fukushima releases

Time profile of the 131I signature in seaweed

Date03/11 03/18 03/25 04/01 04/08

Sp

ecif

ic a

ctiv

ity

[Bq

/kg

]

0

100

200

300

400

500SFU North Vancouver

Bamfield Marine Science Center

I in seaweed131Specific activity of

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 21 / 22

Page 22: SFU Radiation Presentation

Monitoring of Fukushima releases

Time profile of the 131I signature

Date03/11 03/18 03/25 04/01 04/08

Sp

ecif

ic a

ctiv

ity

[arb

itra

ry]

0

5

10

15

20

25rainwater

seaweed NV

seaweed BMSC

I131Specific activity of

Krzysztof Starosta (SFU) The Fukushima Nuclear Crisis April 11, 2011 22 / 22