[Code of Federal Regulations]
[Title 40, Volume 24]
[Revised as of July 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR191.12]

[Page 9-10]
WASTES--Table of Contents
             Subpart B_Environmental Standards for Disposal
Sec. 191.12  Definitions.

    Unless otherwise indicated in this subpart, all terms shall have the 
same meaning as in subpart A of this part.
    Accessible environment means: (1) The atmosphere; (2) land surfaces; 
(3) surface waters; (4) oceans; and (5) all of the lithosphere that is 
beyond the controlled area.
    Active institutional control means: (1) Controlling access to a 
disposal site by any means other than passive institutional controls; 
(2) performing maintenance operations or remedial actions at a site, (3) 
controlling or cleaning up releases from a site, or (4) monitoring 
parameters related to disposal system performance.
    Annual committed effective dose means the committed effective dose 
resulting from one-year intake of radionuclides released plus the annual 
effective dose caused by direct radiation from facilities or activities 
subject to subparts B and C of this part.
    Aquifer means an underground geological formation, group of 
formations, or part of a formation that is capable of yielding a 
significant amount of water to a well or spring.
    Barrier means any material or structure that prevents or 
substantially delays movement of water or radionuclides toward the 
accessible environment. For example, a barrier may be a geologic 
structure, a canister, a waste form with physical and chemical 
characteristics that significantly decrease the mobility of 
radionuclides, or a material placed over and around waste, provided that 
the material or structure substantially delays movement of water or 
    Controlled area means: (1) A surface location, to be identified by 
passive institutional controls, that encompasses no more than 100 square 
kilometers and extends horizontally no more than five kilometers in any 
direction from the outer boundary of the original location of the 
radioactive wastes in a disposal system; and (2) the subsurface 
underlying such a surface location.
    Disposal system means any combination of engineered and natural 
barriers that isolate spent nuclear fuel or radioactive waste after 
    Dose equivalent means the product of absorbed dose and appropriate 
factors to account for differences in biological effectiveness due to 
the quality of radiation and its spatial distribution in the body; the 
unit of dose equivalent is the ``rem'' (``sievert'' in SI units).
    Effective dose means the sum over specified tissues of the products 
of the dose equivalent received following an exposure of, or an intake 
of radionuclides into, specified tissues of the body, multiplied by 
appropriate weighting factors. This allows the various tissue-specific 
health risks to be summed into an overall health risk. The method used 
to calculate effective dose is described in appendix B of this part.
    Ground water means water below the land surface in a zone of 
    Heavy metal means all uranium, plutonium, or thorium placed into a 
nuclear reactor.
    Implementing agency means:
    (1) The Commission for facilities licensed by the Commission;
    (2) The Agency for those implementation responsibilities for the 
Waste Isolation Pilot Plant, under this part, given to the Agency by the 
Waste Isolation Pilot Plant Land Withdrawal Act (Pub. L. 102-579, 106 
Stat. 4777) which, for the purposes of this part, are:
    (i) Determinations by the Agency that the Waste Isolation Pilot 
Plant is in compliance with subpart A of this part;
    (ii) Issuance of criteria for the certifications of compliance with 
subparts B and C of this part of the Waste Isolation Pilot Plant's 
compliance with subparts B and C of this part;
    (iii) Certifications of compliance with subparts B and C of this 
part of

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the Waste Isolation Pilot Plant's compliance with subparts B and C of 
this part;
    (iv) If the initial certification is made, periodic recertification 
of the Waste Isolation Pilot Plant's continued compliance with subparts 
B and C of this part;
    (v) Review and comment on performance assessment reports of the 
Waste Isolation Pilot Plant; and
    (vi) Concurrence by the Agency with the Department's determination 
under Sec. 191.02(i) that certain wastes do not need the degree of 
isolation required by subparts B and C of this part; and
    (3) The Department of Energy for any other disposal facility and all 
other implementation responsibilities for the Waste Isolation Pilot 
Plant, under this part, not given to the Agency.
    International System of Units is the version of the metric system 
which has been established by the International Bureau of Weights and 
Measures and is administered in the United States by the National 
Institute of Standards and Technology. The abbreviation for this system 
is ``SI.''
    Lithosphere means the solid part of the Earth below the surface, 
including any ground water contained within it.
    Passive institutional control means: (1) Permanent markers placed at 
a disposal site, (2) public records and archives, (3) government 
ownership and regulations regarding land or resource use, and (4) other 
methods of preserving knowledge about the location, design, and contents 
of a disposal system.
    Performance assessment means an analysis that: (1) Identifies the 
processes and events that might affect the disposal system; (2) examines 
the effects of these processes and events on the performance of the 
disposal system; and (3) estimates the cumulative releases of 
radionuclides, considering the associated uncertainties, caused by all 
significant processes and events. These estimates shall be incorporated 
into an overall probability distribution of cumulative release to the 
extent practicable.
    Radioactive material means matter composed of or containing 
radionuclides, with radiological half-lives greater than 20 years, 
subject to the Atomic Energy Act of 1954, as amended.
    SI unit means a unit of measure in the International System of 
    Sievert is the SI unit of effective dose and is equal to 100 rem or 
one joule per kilogram. The abbreviation is ``Sv.''
    Undisturbed performance means the predicted behavior of a disposal 
system, including consideration of the uncertainties in predicted 
behavior, if the disposal system is not disrupted by human intrusion or 
the occurrence of unlikely natural events.
    Waste, as used in this subpart, means any spent nuclear fuel or 
radioactive waste isolated in a disposal system.
    Waste form means the materials comprising the radioactive components 
of waste and any encapsulating or stabilizing matrix.

[50 FR 38084, Sept. 19, 1985, as amended at 58 FR 66414, Dec. 20, 1993]