Dissolved Noble Gases in Liquid Effluents and Compliance With Technical Specifications 3.11.1
See the memorandum from L. J. Cunningham to F. J. Hebdon (and others) dated July 12, 1987.
The TS limit for dissolved or entrained noble gases in liquids is 200 picocurie/ml total activity. This limit is independent of other nuclides. There is no need to include noble gases in the MPC summation formula in Note 1 of Appendix B to 10 CFR Part 20 (§§20.1-20.601). The health physics position was written in the context of 10 CFR 20.106, but it also applies to Section 20.1302 and Appendix B, Note 4, of the "new" 10 CFR Part 20 (§§ 20.1001-20.2401).
Standard Technical Specification 3.11.1 states: "The concentration of radioactive material released in liquid effluents to UNRESTRICTED AREAS ... shall be limited to the concentrations specified in 10 CFR Part 20, Appendix B, Table II, Column 2 for radionuclides other than dissolved or entrained noble gases. For dissolved or entrained noble gases, the concentration shall be limited to 200 picocurie/ml total activity."
In response to an inquiry from a licensee, RPB said that the staff does not consider Part 20, Appendix B to give limits for noble gases in water. Specifically, the footnotes addressing "nuclides not listed above" do not apply to the noble gases because the noble gases are listed. RPB also said that the technical specification limit for noble gases is independent of the concentrations of other nuclides. That is, the LCO is satisfied if noble gas concentration does not exceed 200 picocurie/ml and the concentrations of other nuclides do not add up to more than one MPC equivalent using Note 1 to Appendix B to 10 CFR Part 20 (§§20.1-20.601) [or one DAC equivalent using Note 4 to Appendix B of 10 CFR Part 20 (§§20.2001-20.24010]. Hence, there is no need to include the noble gases in the Part 20 summation formula [i.e., the DAC summation formula in Note 4 of Appendix B to §§20.1001-20.2401].
Regulatory references: 10 CFR 20.106, 10 CFR 20.1302, Technical Specifications
Subject codes: 7.3, 9.2
Page Last Reviewed/Updated Tuesday, October 17, 2017