Appendix I to Part 960 - NRC and EPA Requirements for Postclosure Repository Performance
10:4.0.2.5.42.4.80.15.30 : Appendix I
Appendix I to Part 960 - NRC and EPA Requirements for Postclosure
Repository Performance
Under proposed 40 CFR part 191, subpart B - Environmental
Standards for Disposal, § 191.13, “Containment Requirements”,
specifies that for 10,000 years after disposal (a) releases of
radioactive materials to the accessible environment that are
estimated to have more than one chance in 100 of occurring over a
10,000 year period (“reasonably foreseeable releases”) shall be
projected to be less than the quantities permitted by Table 2 of
that regulation's appendix; and (b) for “very unlikely releases”
(i.e., those estimated to have between one chance in 100 and one
chance in 10,000 of occurring over a 10,000 year period), the
limits specified in Table 2 would be multiplied by 10. The basis
for Table 2 is an upper limit on long term risks of 1,000 health
effects over 10,000 years for a repository containing wastes
generated from 100,000 metric tons of heavy metal of reactor fuel.
For releases involving more than one radionuclide, the allowed
release for each radionuclide is reduced to the fraction of its
limit that insures that the overall limit on harm is not exceeded.
Additionally, to provide confidence needed for compliance with the
containment requirements specified above, § 191.14, “Assurance
Requirements”, specifies the disposal of radioactive waste in
accordance with seven requirements, relating to prompt disposal of
waste; selection and design of disposal systems to keep releases to
the accessible environment as small as reasonably achievable;
engineered and natural barriers; nonreliance on active
institutional controls after closure; passive controls after
closure; natural resource areas; and design of disposal systems to
allow future recovery of wastes.
The guidelines will be revised as necessary after the adoption
of final regulations by the EPA.
The implementation of 40 CFR part 191, subpart B is required by
10 CFR 60.112. 10 CFR 60.113 establishes minimum conditions to be
met for engineered components and ground-water flow; specifically:
(1) Containment of radioactive waste within the waste packages will
be substantially complete for a period to be determined by the NRC
taking into account the factors specified in 10 CFR 60.113(b)
provided that such period shall be not less than 300 years nor more
than 1,000 years after permanent closure of the geologic
repository; (2) the release rate of any radionuclide from the
engineered barrier system following the containment period shall
not exceed one part in 100,000 per year of the inventory of that
radionuclide calculated to be present at 1,000 years following
permanent closure, or such other fraction of the inventory as may
be approved or specified by the NRC, provided that this requirement
does not apply to any radionuclide which is released at a rate less
than 0.1% of the calculated total release rate limit. The
calculated total release rate limit shall be taken to be one part
in 100,000 per year of the inventory of radioactive waste
originally emplaced in the underground facility that remains after
1,000 years of radioactive decay; and (3) the geologic repository
shall be located so that pre-waste-emplacement ground-water travel
time along the fastest path of likely radionuclide travel from the
disturbed zone to the accessible environment shall be at least
1,000 years or such other travel time as may be approved or
specified by the NRC.
The guidelines will be revised as necessary to ensure
consistency with 10 CFR part 60.