United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

Question 96: (a) The roentgen (R) is not defined or used

in revised Part 20; however, many survey instruments and

computer records show dose rates in terms of "mR/h" or

"R/h." Will these survey instrument face pieces and

computer forms have to be changed when revised Part 20 is

implemented? (b) Most radiation instrumentation is

currently calibrated in units of roentgens rather than

rads. A roentgen of x- or gamma-radiation in the energy

range of 0.1 - 3 MeV produces 0.96 rad in tissue. Will

these instruments need to be recalibrated to account for

this difference.

Answer: (a) No. The survey instruments will not need to

be changed. See Question 428 for additional information

concerning the use of the unit "roentgen" and its subunits.

(b) No. It may be assumed that one roentgen equals one rem

or a more accurate conversion factor may be used.

(References: 10 CFR 20.1003, 10 CFR 20.2101).

Page Last Reviewed/Updated Thursday, March 29, 2012