10 C.F.R. Subpart L—Postclosure Public Health and Environmental Standards
Title 10 - Energy
This subpart covers the disposal of radioactive material in the Yucca Mountain repository by DOE. For the purposes of demonstrating compliance with this subpart, to the extent that there may be any conflict with the requirements specified in this subpart and the requirements contained in Subparts A–J of this part, including definitions, the requirements in this subpart shall take precedence. All definitions in subpart K 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. 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: (i) South than 36°40'13.6661" North latitude, in the predominant direction of ground-water flow; and (ii) 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 dose projected to be received by the reasonably maximally exposed individual. 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. 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. DOE must demonstrate that there is a reasonable expectation of compliance with this subpart before a license may be issued. In the case of the specific numerical requirements in §63.311 of this subpart, and if performance assessment is used to demonstrate compliance with the specific numerical requirements in §§63.321 and 63.331 of this subpart, compliance is based upon the mean of the distribution of projected doses of DOE's performance assessments which project the performance of the Yucca Mountain disposal system for 10,000 years after disposal. Reasonable expectation means that the Commission is satisfied that compliance will be achieved based upon the full record before it. Characteristics of reasonable expectation include that it: (1) Requires less than absolute proof because absolute proof is impossible to attain for disposal due to the uncertainty of projecting long-term performance; (2) Accounts for the inherently greater uncertainties in making long-term projections of the performance of the Yucca Mountain disposal system; (3) Does not exclude important parameters from assessments and analyses simply because they are difficult to precisely quantify to a high degree of confidence; and (4) Focuses performance assessments and analyses on the full range of defensible and reasonable parameter distributions rather than only upon extreme physical situations and parameter values. (a) Features, events, and processes that describe the reference biosphere must be consistent with present knowledge of the conditions in the region surrounding the Yucca Mountain site. (b) DOE should not project changes in society, the biosphere (other than climate), human biology, or increases or decreases of human knowledge or technology. In all analyses done to demonstrate compliance with this part, DOE must assume that all of those factors remain constant as they are at the time of submission of the license application. (c) DOE must vary factors related to the geology, hydrology, and climate based upon cautious, but reasonable assumptions consistent with present knowledge of factors that could affect the Yucca Mountain disposal system over the next 10,000 years. (d) Biosphere pathways must be consistent with arid or semi-arid conditions. DOE must demonstrate, using performance assessment, that there is a reasonable expectation that, for 10,000 years following disposal, the reasonably maximally exposed individual receives no more than an annual dose of 0.15 mSv (15 mrem) from releases from the undisturbed Yucca Mountain disposal system. DOE's analysis must include all potential pathways of radionuclide transport and exposure. The reasonably maximally exposed individual is a hypothetical person who meets the following criteria: (a) Lives in the accessible environment above the highest concentration of radionuclides in the plume of contamination; (b) Has a diet and living style representative of the people who now reside in the Town of Amargosa Valley, Nevada. DOE must use projections based upon surveys of the people residing in the Town of Amargosa Valley, Nevada, to determine their current diets and living styles and use the mean values of these factors in the assessments conducted for §§63.311 and 63.321; (c) Uses well water with average concentrations of radionuclides based on an annual water demand of 3000 acre-feet; (d) Drinks 2 liters of water per day from wells drilled into the ground water at the location specified in paragraph (a) of this section; and (e) Is an adult with metabolic and physiological considerations consistent with present knowledge of adults.
Title 10: Energy
PART 63—DISPOSAL OF HIGH-LEVEL RADIOACTIVE WASTES IN A GEOLOGIC REPOSITORY AT YUCCA MOUNTAIN, NEVADA
Subpart L—Postclosure Public Health and Environmental Standards
§ 63.301 Purpose and scope.
§ 63.302 Definitions for Subpart L.
§ 63.303 Implementation of Subpart L.
§ 63.304 Reasonable expectation.
§ 63.305 Required characteristics of the reference biosphere.
Postclosure Individual Protection Standard
§ 63.311 Individual protection standard after permanent closure.
§ 63.312 Required characteristics of the reasonably maximally exposed individual.
Human Intrusion Standard
§ 63.321 Individual protection standard for human intrusion.
DOE must determine the earliest time after disposal that the waste package would degrade sufficiently that a human intrusion could occur without recognition by the drillers. DOE must:
(a) Provide the analyses and its technical bases used to determine the time of occurrence of human intrusion (see §63.322) without recognition by the drillers.
(b) If complete waste package penetration is projected to occur at or before 10,000 years after disposal:
(1) Demonstrate that there is a reasonable expectation that the reasonably maximally exposed individual receives no more than an annual dose of 0.15 mSv (15 mrem) as a result of a human intrusion, at or before 10,000 years after disposal. The analysis must include all potential environmental pathways of radionuclide transport and exposure subject to the requirements at §63.322; and
(2) If exposures to the reasonably maximally exposed individual occur more than 10,000 years after disposal, include the results of the analysis and its bases in the environmental impact statement for Yucca Mountain as an indicator of long-term disposal system performance.
(c) Include the results of the analysis and its bases in the environmental impact statement for Yucca Mountain as an indicator of long-term disposal system performance, if the intrusion is not projected to occur before 10,000 years after disposal.
§ 63.322 Human intrusion scenario.
For the purposes of the analysis of human intrusion, DOE must make the following assumptions:
(a) There is a single human intrusion as a result of exploratory drilling for ground water;
(b) The intruders drill a borehole directly through a degraded waste package into the uppermost aquifer underlying the Yucca Mountain repository;
(c) The drillers use the common techniques and practices that are currently employed in exploratory drilling for ground water in the region surrounding Yucca Mountain;
(d) Careful sealing of the borehole does not occur, instead natural degradation processes gradually modify the borehole;
(e) No particulate waste material falls into the borehole;
(f) The exposure scenario includes only those radionuclides transported to the saturated zone by water (e.g., water enters the waste package, releases radionuclides, and transports radionuclides by way of the borehole to the saturated zone); and
(g) No releases are included which are caused by unlikely natural processes and events.
Ground-Water Protection Standards
§ 63.331 Separate standards for protection of ground water.
DOE must demonstrate that there is a reasonable expectation that, for 10,000 years of undisturbed performance after disposal, releases of radionuclides from waste in the Yucca Mountain disposal system into the accessible environment will not cause the level of radioactivity in the representative volume of ground water to exceed the limits in the following Table 1:
Table 1_Limits on Radionuclides in the Representative Volume------------------------------------------------------------------------ Is natural Radionuclide or type of Limit background radiation emitted included?------------------------------------------------------------------------Combined radium-226 and radium- 5 picocuries per liter Yes. 228.Gross alpha activity 15 picocuries per Yes. (including radium-226 but liter. excluding radon and uranium).Combined beta and photon 0.04 mSv (4 mrem) per No. emitting radionuclides. year to the whole body or any organ, based on drinking 2 liters of water per day from the representative volume.------------------------------------------------------------------------
§ 63.332 Representative volume.(a) The representative volume is the volume of ground water that would be withdrawn annually from an aquifer containing less than 10,000 milligrams of total dissolved solids per liter of water to supply a given water demand. DOE must project the concentration of radionuclides released from the Yucca Mountain disposal system that will be in the representative volume. DOE must use the projected concentrations to demonstrate a reasonable expectation that the Yucca Mountain disposal system complies with §63.331. The DOE must make the following assumptions concerning the representative volume: (1) It includes the highest concentration level in the plume of contamination in the accessible environment; (2) Its position and dimensions in the aquifer are determined using average hydrologic characteristics which have cautious, but reasonable, values representative of the aquifers along the radionuclide migration path from the Yucca Mountain repository to the accessible environment as determined by site characterization; and (3) It contains 3,000 acre-feet of water (about 3,714,450,000 liters or 977,486,000 gallons). (b) DOE must use one of two alternative methods for determining the dimensions of the representative volume. The DOE must propose its chosen method, and any underlying assumptions, to NRC for approval. (1) DOE may calculate the dimensions as a well-capture zone. If DOE uses this approach, it must assume that the: (i) Water supply well(s) has (have) characteristics consistent with public water supply wells in the Town of Amargosa Valley, Nevada, for example, well-bore size and length of the screened intervals; (ii) Screened interval(s) include(s) the highest concentration in the plume of contamination in the accessible environment; and (iii) Pumping rates and the placement of the well(s) must be set to produce an annual withdrawal equal to the representative volume and to tap the highest concentration within the plume of contamination. (2) DOE may calculate the dimensions as a slice of the plume. If DOE uses this approach, it must: (i) Propose, for approval, where the location of the edge of the plume of contamination occurs. For example, the place where the concentration of radionuclides reaches 0.1% of the level of the highest concentration in the accessible environment; (ii) Assume that the slice of the plume is perpendicular to the prevalent direction of flow of the aquifer; and (iii) Assume that the volume of ground water contained within the slice of the plume equals the representative volume. Additional Provisions§ 63.341 Projections of peak dose.To complement the results of §63.311, DOE must calculate the peak dose of the reasonably maximally exposed individual that would occur after 10,000 years following disposal but within the period of geologic stability. No regulatory standard applies to the results of this analysis; however, DOE must include the results and their bases in the environmental impact statement for Yucca Mountain as an indicator of long-term disposal system performance. § 63.342 Limits on performance assessments.DOE's performance assessments shall not include consideration of very unlikely features, events, or processes, i.e., those that are estimated to have less than one chance in 10,000 of occurring within 10,000 years of disposal. DOE's assessments for the human-intrusion and ground-water protection standards shall not include consideration of unlikely features, events, and processes, or sequences of events and processes, i.e., those that are estimated to have less than one chance in 10 and at least one chance in 10,000 of occurring within 10,000 years of disposal. In addition, DOE's performance assessments need not evaluate the impacts resulting from any features, events, and processes or sequences of events and processes with a higher chance of occurrence if the results of the performance assessments would not be changed significantly. [67 FR 62634, Oct. 8, 2002] § 63.343 Severability of individual protection and ground-water protection standards.The individual protection and ground-water protection standards are severable. Browse Previous |
