TABLE 29 OFF-SITE RADIATION SURVEY FROM MATHER POINT, SOUTH RIM OF GRAND CANYON NATIONAL PARK, SOUTH VIA ARIZONA 64 TO US 66 Distance from start miles 0 LO 18 20 28 30 38 ho 48 D-11 Day back- ground mr/hr 0.03 0.02 0.02 0.02 0.02 50 0.03 29.3 0.02 58 D Dose Rate (Shield closed) + 3 Days At time mr/hr hours 0.02 1455 0.01 1521 0.02 1511 0.01 1534 0.02 1555 0.02 1611 0.02 1628