United States Nuclear Regulatory Commission - Protecting People and the Environment

U.S. Nuclear Regulatory Commission

U.S. Nuclear Regulatory Commission

Question 404: NRC Form 5 (Item No. 10) provides for

reporting of individual radionuclides involved in an

intake. How does the NRC plan on using this data (i.e.,

what is the NRC's purpose in collecting this data)?

Answer: NRC Form 5 (Item 10) provides for

recording / reporting of individual radionuclides involved in

an intake because 10 CFR 20.2106, records of individual

monitoring results, requires that the records include, when

applicable, the estimated intake or body burden of

radionuclides. There are several reasons for inclusion of

intake information on Form 5. One reason is that if the

internal dose models and weighting factors are changed at

some future date, the NRC can recalculate the reported

doses using the new models and weighting factors. Another

reason, of benefit to licensees, is to make it possible for

a licensee to determine the CDE to the maximally exposed

organ for an individual who has organ doses reported from

previous employers. For example, consider an individual,

who, during a year, was employed by licensee A and received

a CDE of 20 rem to the lung, then was employed by licensee

B and received a CDE of 20 rem to the bone, and finally was

employed by licensee C and received a CDE of 20 rem to the

thyroid. NRC Form 5 does not provide a space for recording

which organ is the maximally exposed organ (unless the

"Comments" space is used for this purpose). In the absence

of information on which organ was maximally exposed and on

the intakes of individual radionuclides, the total CDE to

the maximally exposed organ in this example would be

considered to be the total of these three 20-rem doses (to

different organs), or a total of 60 rem, which would appear

to be a potential violation of the organ dose limit. With

the individual radionuclide intake information, the CDE to

the maximally exposed organ could be recalculated and very

likely would be below the limit. The NRC will also use the

intake data from some of the earlier reports to the NRC

under revised Part 20 to recalculate the doses to ensure

that the reported doses are reasonably consistent (within a

factor of 2 or so). Finally, the recordkeeping and

reporting requirements of revised Part 20 are consistent

with implementing an NRC staff recommendation to establish

a registry of radiation workers and their radiation doses.

Such a registry will be of value for a number of reasons,

one of which is to facilitate epidemiological studies of

potential radiation-induced health effects. The inclusion

of the radionuclide intake data in the dose records

provides a better basis for these studies than records of

dose alone. (References: 10 CFR 20.2106, 10 CFR 20.2206,

Regulatory Guide 8.7).

Page Last Reviewed/Updated Thursday, March 29, 2012