U.S. Nuclear Regulatory Commission
... Dissolved Noble Gases in Liquid Effluents and Compliance With Technical Specifications 3.11.1
Title: ... 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,
Subject codes: 7.3, 9.2