Page 413 - Emergency Response Book

Answer 23

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

• For Co-60 RHM = 1.25 R/hr/Ci at 1 meter

Dose rate for 30Ci of Co-60 at 1 meter

= 30 x 1.25 x 1000 mR

= 37500 mR/hr

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

37500 mR/hr x (1 m x 1 m) = I mR/hr x (2 m x 2 m)

2

I = 37500 mR/hr / 4 m 2

2

I = 9375 mR/hr

2

Therefore max allowable stay time = 1000 mR / ( 9375 mR/hr)

= 0.106 hr

= 0.106 hr (60 min/hr)

= 6.4 minutes.

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