Effluent from nuclear facilities is permitted under regulations promulgated by the U.S. Nuclear Regulatory Commission, though it is controlled, monitored, and reported to authorities. These following requirements are intended to keep public exposures from radioactive effluent releases at levels that are as low as reasonably achievable (ALARA).
Title 10, Part 20 of the Code of Federal Regulations (10 CFR 20, Standards for Protection Against Radiation) establishes public dose limits for radioactive releases from nuclear plants. Specifically, Subpart D (Radiation Dose Limits for Individual Members of the Public) requires that nuclear plant licensees conduct operations so that:
- The total effective dose equivalent1 to individual members of the public does not exceed 0.1 rem (1 mSv) in a year; and
- The dose in any unrestricted area2 from external sources does not exceed 0.002 rem (0.02 mSv) in any one hour.
However, a licensee may apply for authorization to operate up to an annual dose limit of 0.5 rem (5 mSv) for an individual member of the public if there is a demonstrated need for the elevated exposures. However, there
1 Total effective dose equivalent (TEDE) expresses the dose received by an individual in terms of a uniform whole-body dose, even though that actual dose may have been received by a particular organ or part of the body. The use of TEDE allows for comparisons of exposure risks for different kinds and levels of exposures.
2 Unrestricted area is defined in 10 CFR 20.1003 as “an area, access to which is neither limited nor controlled by the licensee.”
are additional requirements specified in 10 CFR 20.1301 that must be met by the licensee to obtain authorization for a higher dose limit.
To show compliance with these dose limits, licensees are required to survey radiation levels in unrestricted and controlled areas, as well as in the effluents released in these areas. The licensee must demonstrate that the total effective dose equivalent to the individual likely to receive the highest dose from the plant does not exceed the annual dose limit noted above; this demonstration can be made either by measurement or calculation. Alternatively, the licensee can demonstrate that the annual average concentrations of radioactive material released in airborne and liquid effluents at the boundary of the unrestricted area do not exceed radionuclide-specific values provided in the regulations,3 and also that an individual continuously present in an unrestricted area would receive a dose not to exceed 0.002 rem (0.02 mSv) in an hour and 0.05 rem (0.5 mSv) in a year.
There are additional regulations on the control of effluent releases for nuclear power plants in 10 CFR 50. Part 50.34a (Design objectives for equipment to control releases of radioactive material in effluents) requires applicants for nuclear plant construction permits to estimate future releases for:
(i) The quantity of each of the principal radionuclides expected to be released annually to unrestricted areas in liquid effluents produced during normal reactor operations; and
(ii) The quantity of each of the principal radionuclides of the gases, halides, and particulates expected to be released annually to unrestricted areas in gaseous effluents produced during normal reactor operations.
Additionally, 10 CFR 50.36(a)(2) requires licensees to submit annual reports specifying the principal radionuclides released in liquid and gaseous effluents.
Part 50.36a (Technical specifications on effluents from nuclear power reactors) requires licensees to establish and follow procedures for the control of effluents. This Part also establishes an expectation that “the licensee will exert its best efforts to keep levels of radioactive material in effluents as low as is reasonably achievable.”4
The release requirements for radioactive effluents are based on the calculated doses to members of the public from the effluents, and not on the total volume or type of radioactive material discharged. Thus, licensees have the discretion to control effluent releases in a manner that allows for
plant specific discharge streams, as well as the local setting of the plant. Compliance with 10 CFR 50.36a and Appendix I of 10 CFR 50 is established in a Licensee’s radiological effluent release technical specifications, as based on dose calculations to a hypothetical maximally exposed member of the public living near the nuclear power plant.
Regulations promulgated by the U.S. Environmental Protection Agency place additional requirements on releases from all fuel-cycle facilities. The regulations in 40 CFR 190 (Environmental Radiation Protection Standards for Nuclear Power Operations), Subpart 10 (Standards for Normal Operations) place annual limits of 0.025 rem (0.25 mSv) to the whole body, 0.075 rem (0.75 mSv) to the thyroid, and 0.025 rem (0.25 mSv) to any other organ of any member of the public as the result of planned discharges of radioactive materials, excluding radon and its progeny, to the general environment from uranium fuel-cycle operations and of exposures to radiation from these operations.