Page 412 - Emergency Response Book

Answer 22

• During the emergency, responder is allowed to received dose = 1000mR @ 10 mSv

• For Ir-192 RHM = 0.5R/hr/Ci at 1 meter

Dose rate for 30Ci of Ir-192 at 1 meter

= 30 x 0.5 x 1000 mR

= 15000 mR/hr

Using formula I d 1 2 = I d to get dose rate at 2 meter
2
2 2
1

15000 mR/hr x (1 m x 1 m) = I mR/hr x (2 m x 2 m)

2

I = 15000 mR/hr / 4 m 2

2

I = 3750 mR/hr

2

Therefore max allowable stay time = 1000 mR /( 3750 mR/hr)

= 0.26 hr

= 0.26 hr (60 min/hr)

= 15.99 minutes.

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