“Nuclear Radiation, Environment and Energy” Workshop

General discussion on the Daya Baycontingency plan( 大亞灣應變計劃的通識討論 )

香港理工大學應用物理系王碧裕

-50 km from Tsim Sha Tsui

http://www.sb.gov.hk/eng/emergency/dbcp/c01_eng.pdf (Annex 1.1)

Platform of spreading

radioactive plume(輻射煙羽 )Half-life: 8 daysgaseous and volatile

Ingestion of contaminated foodstuffs and drinking waterHalf-life: 30 yearsWater-soluble

-release of radioactive fission products (放射性裂變產物 ) into the atmosphere

http://news.wenweipo.com/2011/03/25/IN1103250068_p1.htm

TECHNICAL WORKING GROUP ( 技術工作小組 ) - Secretary for Security or his representative (Chairman)

2. IAEA four-category system (國際原子能機構的四級分類系統 ) (classifying nuclear power emergencies)

Decision on the activation level of the plan ( 決定應變計劃的動階段 )

1. Technical advice from these key departments

Four-category system (四級分類系統 )

Counter-measures in activation levels ( 動階段 )

3. Site Emergency (站址緊急情況 )

4. Off-Site Emergency (站外緊急情況 )

1. Plume Exposure Pathway Counter-measure

( 煙羽防護措施 )2. Ingestion Pathway Counter-measure

( 飲食防護措施 )

1. Plume Exposure Pathway Counter-measure ( 煙羽防護措施 )

Counter-measures

(a) Evacuation or sheltering ( 疏散或掩蔽 )

-only apply to Ping Chau (坪洲 )

(within 20 km of the nuclear plant)

(ii)Sheltering (掩蔽 )

(i)Evacuation (疏散 )

http://www.sb.gov.hk/eng/emergency/dbcp/c01_eng.pdf (Annex 1.1)

1. Plume Exposure Pathway Counter-measure ( 煙羽防護措施 )

Counter-measures

(b) Monitoring the radiation level (輻射水平監測 )of - persons who have been within the 20 km range- incoming cargo

(c) Issue of potassium iodate tablet (派發碘酸鉀藥片 )

2. Ingestion Pathway Counter-measure ( 飲食防護措施 )

(a) Control of food and livestock (食物及禽畜管制 )

(b) Control of water (水質管制 )

-1000 Bq/kg

Operational criteria for evacuation (IAEA)

http://www-pub.iaea.org/MTCD/meetings/PDFplus/2011/cn200/working-sessions/w_d3_K.Hirose.pdf (p.5)

Air Dose Rate Readingson 17th March, 2011

=170.0µSv/hr

Major factors that affect the spreading of plume1. Distance2. Dilution by the atmosphere

Google map

Major factors that affect the spreading of plume1. Distance2. Dilution by the atmosphere

Criteria for evacuation:> 297.62µSv/hr

MODEL 1:

Spread in “sphere”

Major factors that affect the spreading of plume1. Distance2. Dilution by the atmosphere

MODEL 2:

Major factors that affect the spreading of plume1. Distance2. Dilution by the atmosphere

Spread in “sphere”km µSv/hr

22 475.6264

23 416.2464

24 366.3534

25 324.1261

26 288.1469

27 257.3017

28 230.7065

29 207.6539

30 187.573

Criteria for evacuation:> 297.62µSv/hr

MODEL 2:

Wind:- wind direction

affect the direction of dispersion

- wind speed affect the rate of dispersion

Uncertainties that affect the spreading of plume1. Size of explosion2. Weather (Wind, Rain)

Rain :- rainfall greatly enhance the deposition rate → Radiation level in air ↓

“First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village.” --- IAEA

Google map

Reference data:Akogi Teshichiro, Namie Town, Futaba County (双叶郡浪江町赤宇木手七郎 )- 31km from Fukushima Dai-ichi Nuclear Power Plant

Time for the evacuation zone to safety level

17/3/2011 – 23/4/2011Criteria for evacuation : > 297.62µSv/hr

http://eq.wide.ad.jp/index_en.html (April 24th version -http://eq.wide.ad.jp/files_en/110424map_1800rev2_en.pdf)

Days µSv/hr

232 11.53592

233 11.50164

234 11.4676

235 11.43381

236 11.40026

237 11.36696

238 11.33388

239 11.30105

240 11.26844

Time for the evacuation zone to safety level

<11.42µSv/hr

THE END