Question 22: Alarm setpoints for many radiation monitors
are based on 10 CFR 20 Appendix B concentrations. Will
these new changes require numerous ODCM changes, setpoint
change requests, and procedure changes?
Answer: Separate answers are provided for reactor and
materials licensees because these answers are somewhat
different.
Reactor Licensees: Alarm setpoints for airborne effluent
monitors are not likely to change. These monitors are
typically set up to detect an effluent concentration which
would yield a whole body dose rate of 500 mrem/y or a
thyroid dose rate of 1500 mrem/y (or fraction thereof) in
an unrestricted area on an instantaneous basis, as required
by the Technical Specifications. Since other limiting
conditions are also contained in Technical Specifications
to restrict annual doses to the public to much smaller
values than those implied above, and since short-term
operational flexibility is necessary, it is unlikely that
changes would need to be made in the alarm setpoints for
airborne effluent monitors.
Alarm setpoints for waterborne effluent monitors are likely
to require change, since they are based on 10 CFR 20
Appendix B concentrations, as required by the Technical
Specifications. Because Appendix B concentration values
differ for many radionuclides between the revised and old
versions of Part 20, liquid effluent monitor alarm
setpoints may have to be changed.
For reactors, the extent of staff involvement and licensee
efforts in adjusting and documenting alarm setpoints will
depend on whether the licensee has implemented NRR Generic
Letter 89-01. (References: 10 CFR 20 Appendix B, Reactor
Technical Specifications, NRR Generic Letter 89-01)
Materials Licensees: Area monitor alarm setpoints for most
materials licensees that are currently required to conduct
continuous air monitoring will in all likelihood require
change. This is especially true for those facilities that
handle significant quantities of source and special nuclear
material since the new DACs for these types of material are
lower or more restrictive than the old MPCs. It should be
noted that for commonly occurring thorium-232 (Th-232) and
uranium 238 (U-238) in the oxide (insoluble) form, the DACs
are lower than the MPCs by factors of 30 and 5,
respectively. Similarly, alarm setpoints for both airborne
and waterborne releases for most materials licensees would
have to be modified. It should also be noted that for
airborne releases, the allowable concentrations for
insoluble Th-232 and U-238 have been reduced by factors of
about 170 and 80, respectively. For waterborne releases,
the allowable release concentrations for soluble Th-232 and
U-238 have been reduced by factors of about 70 and 130,
respectively. For these reasons, it is anticipated that
numerous procedural changes will have to be made for
licensees handling significant quantities of source and
special nuclear material.