[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: 40CFR197.12]



[Page 64-65]

 

                   TITLE 40--PROTECTION OF ENVIRONMENT

 

         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)

 

PART 197_PUBLIC HEALTH AND ENVIRONMENTAL RADIATION PROTECTION STANDARDS 

FOR YUCCA MOUNTAIN, NEVADA--Table of Contents

 

    Subpart B_Public Health and Environmental Standards for Disposal

 

Sec.  197.12  What definitions apply in subpart B?



    All definitions in subpart A of this part and the following:

    Accessible environment means any point outside of the controlled 

area, including:

    (1) The atmosphere (including the atmosphere above the surface area 

of the controlled area);

    (2) Land surfaces;

    (3) Surface waters;

    (4) Oceans; and

    (5) The lithosphere.

    Aquifer means a water-bearing underground geological formation, 

group of formations, or part of a formation (excluding perched water 

bodies) that can yield a significant amount of ground water to a well or 

spring.

    Barrier means any material, structure, or feature that, for a period 

to be determined by NRC, prevents or substantially reduces the rate of 

movement of water or radionuclides from the Yucca Mountain repository to 

the accessible environment, or prevents the release or substantially 

reduces the release rate of radionuclides from the waste. For example, a 

barrier may be a geologic feature, an engineered 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 the waste, provided that the material 

substantially delays movement of water or radionuclides.

    Controlled area means:

    (1) The surface area, identified by passive institutional controls, 

that encompasses no more than 300 square kilometers. It must not extend 

farther:

    (a) South than 36[deg]40[min]13.6661[sec] north latitude, in the 

predominant direction of ground water flow; and

    (b) Than five kilometers from the repository footprint in any other 

direction; and

    (2) The subsurface underlying the surface area.

    Disposal means the emplacement of radioactive material into the 

Yucca Mountain disposal system with the intent of isolating it for as 

long as reasonably possible and with no intent of recovery, whether or 

not the design of the disposal system permits the ready recovery of the 

material. Disposal of radioactive material in the Yucca Mountain 

disposal system begins when all of the ramps and other openings into the 

Yucca Mountain repository are sealed.

    Ground water means water that is below the land surface and in a 

saturated zone.

    Human intrusion means breaching of any portion of the Yucca Mountain 

disposal system, within the repository footprint, by any human activity.

    Passive institutional controls means:

    (1) Markers, as permanent as practicable, placed on the Earth's 

surface;

    (2) Public records and archives;

    (3) Government ownership and regulations regarding land or resource 

use; and

    (4) Other reasonable methods of preserving knowledge about the 

location, design, and contents of the Yucca Mountain disposal system.

    Peak dose means the highest annual committed effective dose 

equivalent projected to be received by the reasonably maximally exposed 

individual.

    Performance assessment means an analysis that:

    (1) Identifies the features, events, processes, (except human 

intrusion), and sequences of events and processes (except human 

intrusion) that might affect the Yucca Mountain disposal system and 

their probabilities of occurring during 10,000 years after disposal;

    (2) Examines the effects of those features, events, processes, and 

sequences of events and processes upon the performance of the Yucca 

Mountain disposal system; and

    (3) Estimates the annual committed effective dose equivalent 

incurred by the reasonably maximally exposed individual, including the 

associated uncertainties, as a result of releases caused by all 

significant features, events, processes, and sequences of events and 

processes, weighted by their probability of occurrence.

    Period of geologic stability means the time during which the 

variability of geologic characteristics and their future behavior in and 

around the Yucca Mountain site can be bounded, that is, they can be 

projected within a reasonable range of possibilities.



[[Page 65]]



    Plume of contamination means that volume of ground water in the 

predominant direction of ground water flow that contains radioactive 

contamination from releases from the Yucca Mountain repository. It does 

not include releases from any other potential sources on or near the 

Nevada Test Site.

    Repository footprint means the outline of the outermost locations of 

where the waste is emplaced in the Yucca Mountain repository.

    Slice of the plume means a cross-section of the plume of 

contamination with sufficient thickness parallel to the prevalent 

direction of flow of the plume that it contains the representative 

volume.

    Total dissolved solids means the total dissolved (filterable) solids 

in water as determined by use of the method specified in 40 CFR part 

136.

    Undisturbed performance means that human intrusion or the occurrence 

of unlikely natural features, events, and processes do not disturb the 

disposal system.

    Undisturbed Yucca Mountain disposal system means that the Yucca 

Mountain disposal system is not affected by human intrusion.

    Waste means any radioactive material emplaced for disposal into the 

Yucca Mountain repository.

    Well-capture zone means the volume from which a well pumping at a 

defined rate is withdrawing water from an aquifer. The dimensions of the 

well-capture zone are determined by the pumping rate in combination with 

aquifer characteristics assumed for calculations, such as hydraulic 

conductivity, gradient, and the screened interval.

    Yucca Mountain disposal system means the combination of underground 

engineered and natural barriers within the controlled area that prevents 

or substantially reduces releases from the waste.