Protection of the Embryo/Fetus, Minors, and Members of the Public

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

-- for the embryo/fetus of a declared pregnant worker, the summation of the deep dose

equivalent to the mother from external exposure during the entire gestation period and

the gestation period dose equivalent to the embryo/fetus from intakes by the mother

during the entire gestation period.

Doses should be calculated and recorded for any confirmed plutonium intake. What

constitutes a confirmed intake is discussed in Section 5.7. Along with the doses, supporting

records must be maintained, including the bioassay data, assumptions, biokinetic models,

and calculational methods used to estimate the doses. These may be included in letter-report

dose assessments, databases, technical basis documents, and similar records, either singly or

in combination.

5.1.2 Protection of the Embryo/Fetus, Minors, and Members of the Public

The dose equivalent limit for the embryo/fetus of a declared pregnant worker is 0.5 rem for

the entire gestation period, defined as the summation of external dose received and internal

dose received during the gestation period (not the 50-year committed internal dose). Internal

exposure monitoring is required if an intake is likely to result in more than 10% of that limit

(i.e., 50 mrem for the gestation period). As discussed in more detail in Section 5.6.,

providing adequate protection to keep the mother's intakes below the occupational limits will

also provide adequate protection for the embryo/fetus. Thus, special bioassay for plutonium

or americium related to pregnancy is not required. As a matter of caution, some sites try to

obtain baseline bioassays as soon as a pregnancy is declared, with another baseline bioassay

following the end of pregnancy. Some sites also offer to restrict pregnant workers from jobs

with relatively high potential for occupational intakes.

Minors and members of the public are limited, in part, by 10 CFR 835.207 and 10 CFR

835.208 (DOE, 1998a) to a TEDE of 0.1 rem/year. Internal exposure monitoring is required

if an intake is likely to result in 50% of that limit (0.05 rem). As noted in Section 5.1.1,

because bioassay monitoring is not likely to be sufficiently sensitive to identify such intakes

on a routine basis, enhanced workplace surveillance or restriction of access may be required.

5.2

CHARACTERIZATION OF INTERNAL HAZARDS

Plutonium can be encountered in a wide range of mixtures, e.g., a pure isotope in a standard

solution, a highly variable combination of isotopes in so-called "weapons grade" or "fuels grade"

Pu, or commercial spent fuel. In addition, the age of a mixture significantly affects its isotopic

composition. As a typical weapons or fuels grade mixture ages, the 241Pu decays to 241Am.

Although the mass changes may be quite small, the overall result can be a significant build-up of

241

Am radioactivity with time. This buildup can make the mixture somewhat easier to detect by

in vivo methods. Table 5.4 shows some example plutonium mixtures which might be encountered

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