November 23, 1999
Central Docket Section (6102)
U.S. Environmental Protection Agency
401 M Street, SW
Washington, D.C. 20460-0001
RE: ENVIRONMENTAL RADIATION PROTECTION STANDARDS FOR YUCCA MOUNTAIN, NEVADA. PROPOSED RULE 40 CFR PART 197 (64 FR NO. 166, FRIDAY, AUGUST 27, 1999, PP. 46976-47016.
ATTN: Docket A-95-12
These comments on the proposed Environmental Radiation Protection Standards for Yucca Mountain, Nevada, are being submitted on behalf of the State of Nevada. The Agency for Nuclear Projects Nuclear Waste Project Office was established by the Nevada Legislature in 1985 to carry out the State's duties in overseeing all aspects of the federal high-level nuclear waste program pursuant to the Nuclear Waste Policy Act. Reviewing and commenting on proposed actions by the Environmental Protection Agency regarding standards for storage and disposal of high-level nuclear waste is within the Agency for Nuclear Project's statutory assignment.
In Public Hearings on the Proposed Rule, 40 CFR Part 197, on October 19, 1999, in Amargosa Valley, Nevada, and on October 20, 1999, in Las Vegas, we presented summary oral comments on behalf of the State of Nevada. Our statement included our general position on the Proposed Rule as follows:
"With the exception of the regulatory period, in general, this Proposed Rule for a Yucca Mountain repository should be at least consistent with the EPA's standard (40 CFR Part 191) that has been applied to the geologic repository at the DOE's Waste Isolation Pilot Plant (WIPP), in New Mexico. Ideally, a geologic repository should provide complete isolation of the waste from the biosphere for its hazardous lifetime, but recognizing this may not be attainable through a convincing performance assessment, the safety standard for a high-level nuclear waste repository [at Yucca Mountain] should be no less stringent than that applied to the repository for transuranic wastes at WIPP. This would lead to the controlled area being no larger than 100 square kilometers, with its boundary being no farther than 5 kilometers from the location of the emplaced waste, and include the groundwater beneath it. It would also include an all pathway dose limit of 15 mrem per year, and a ground water protection standard equivalent to that applied under the Safe Drinking Water Act. From a site-specific perspective, groundwater quality protection is a major concern, because unlike WIPP, the potable ground water resource at Yucca Mountain is a resource shared by the public, and it should be at least as well protected as ground water supplies throughout the nation."
Regarding the regulatory period, or period of compliance, we concluded that "any standard that does not require compliance at the time of expected peak dose is inadequate."
The original authority for EPA to promulgate standards for geologic repositories is found in the Nuclear Waste Policy Act of 1982, as amended. The Act adopted deep geologic disposal as the national policy for permanent disposal of spent nuclear fuel and high-level radioactive waste. The selection of deep geologic disposal as national policy was an outcome of the Department of Energy's 1980 Final Environmental Impact Statement, Management of Commercially Generated Radioactive Waste. This EIS states, "Geologic barriers are expected to provide isolation of the waste for at least 10,000 years after the waste is emplaced in a repository and probably will provide isolation for millennia thereafter. Engineered barriers are those designed to assure total containment of the waste within the disposal package during the initial period during which most of the intermediate-lived fission products decay. This time period might be as long as 1,000 years..." (Page 5-1). The Nuclear Waste Policy Act requires that a system of multiple barriers be used in the design of a repository. The only basis for this concept of multiple barriers is that described in the 1980 EIS.
The Proposed Rule, through its definitions of "disposal" and "barrier" has inappropriately skewed the basic notion of geologic disposal through the use of multiple barriers to accommodate the known inadequacy of the Yucca Mountain site to isolate waste from the biosphere. The proposed definition of "disposal" is "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..." (emphasis added). This definition wrongly sets the goal of a repository to be the delay of releases of radionuclides, rather than isolation of the waste, which can include a controlled rate of release and transport.
The concept of delay of releases rather than prevention or control of releases is amplified in the example of a "barrier" accompanying its definition. The definition correctly refers to a material, structure, or feature that prevents or substantially reduces the rate of radionuclide release or transport. But, the definition then provides an example (originally appearing, incorrectly, in 40 CFR 191) that announces that a barrier "substantially delays movement of water or radionuclides" (emphasis added). Prevention or substantial reduction of rate of release or transport does not equate with delay of release or transport.
The distinction between delay of release and substantial reduction in rate of release or transport is an important one in considering the safety of a Yucca Mountain repository. Contrary to the multiple barrier concept of the 1980 EIS, the natural barriers of the Yucca Mountain site alone have little ability to isolate waste. The DOE's Yucca Mountain repository concept is one of reliance on the longevity of the engineered barriers to delay essentially all releases until after the proposed 10,000-year regulatory period. In DOE's repository performance assessments, the primary factor controlling the calculated doses to individuals through time, before and after the proposed 10,000-year regulatory period, is the failure rate of the thousands of waste containers. The magnitude of the calculated peak dose is indicated to be essentially the same (and far above any reasonable safety standard), regardless of the projected failure rate of the containers. Put simply, this condition does not conform to the concept of geologic disposal described in the 1980 EIS and adopted into national policy by the Nuclear Waste Policy Act. The EPA has no authority to revise or manipulate the concept through its regulations. While the Energy Policy Act of 1992 dictated certain aspects of the site-specific repository standard for Yucca Mountain, it did not change the concept and goal of a nuclear waste repository from that described in the 1980 EIS.
"Reasonable Expectation" That the Standards Will Be Met
The introduction of a new, untried standard of judgement for a repository licensing decision in this Proposed Rule is not necessary or appropriate. It also may imply that the determination requires less rigorous "proof" than that associated with the NRC's "reasonable assurance" approach, which has a long history of implementation. There are sufficient large uncertainties in the assessment of Yucca Mountain repository performance without introducing a new major regulatory uncertainty into the licensing process.
Use of Expert Opinion
The NRC's NUREG-1563, "Branch Technical Position on the Use of Expert Elicitation in the High-Level Radioactive Waste Program," provides an acceptable functional guide, if applied as intended. It would not be productive to reopen this issue for consideration when the basic principles and methods have already been explored and the existing guidance is seen as reasonable.
SPECIFIC QUESTIONS FOR COMMENT:
1. The NAS recommended that we base the individual protection standard upon risk. Consistent with this recommendation and the statutory language of the EnPA [Energy Policy Act of 1992], we are proposing a standard in terms of annual CEDE [Committed Effective Dose Equivalent] incurred by individuals. Is our rationale for this aspect of our proposal reasonable?
Response: Yes, without elaboration.
2. We are proposing an annual limit of 15 mrem CEDE to protect the RMEI [Reasonably Maximally Exposed Individual] and the general public from releases from waste disposed of in the Yucca Mountain disposal system. Is our proposed standard reasonable to protect both individuals and the general public?
Response: Yes. As stated above, ideally a nuclear waste repository should provide complete isolation of the radionuclides from the environment. However, recognizing that demonstration of such isolation is not possible due to the longevity of the hazard of some components of this waste, the standard (40 CFR 197) should be at least consistent with the standard applied to WIPP for disposal of transuranic wastes. That standard (40 CFR Part 191) sets a limit of 15 mrem for the annual CEDE.
3. To define who should be protected by the proposed individual-protection standard, we are proposing to use an RMEI as the representative of the rural-residential CG [Critical Group]. Is our approach reasonable? Would it be more useful to have DOE calculate the average dose occurring within the rural-residential CG rather than the RMEI dose?
Response: No, the approach is not reasonable. The exposed individual considered for compliance purposes should be a weighted age/gender subsistence farmer. The exposed individual in the Proposed Rule represents a rural-residential lifestyle, which is said to be nearly equivalent to that of the average member of the critical group that has been recommended by some as the exposed individual. If, as stated in the commentary for this Proposed Rule, the risk from a Yucca Mountain repository to the average member of the critical group is about one-half of that to a subsistence farmer, then the more stringent exposure case should be applied, especially since it is not an unreasonable future scenario in the vicinity of Yucca Mountain. Given the broad uncertainties (ranging to orders of magnitude) in the dose and risk calculations for a Yucca Mountain repository, selection of an exposed individual for compliance purposes who is only at twice the risk of that proposed in the rule is reasonable and conservative. It also provides a more defensible lifestyle description than that compiled from vicinity surveys for the rural-residential lifestyle. (See also our response to Question 5.)
4. Is it reasonable to use RME [Reasonable Maximum Exposure] parameter values based upon characteristics of the population currently located in proximity to Yucca Mountain? Should we promulgate specific parameter values in addition to specifying the exposure scenarios?
Response: The exposure scenario of the weighted age/gender subsistence farmer should be specified, consistent with that of a maximally exposed individual drinking 2 liters of water per day from a well located in ground water with maximum radionuclide concentration and living and growing all his food at a location adjacent to or near the boundary of the repository, using water produced from the same well.
5. Is it reasonable to consider, select, and hold constant today's known and assumed attributes for the biosphere for use in projecting radiation-related effects upon the public of releases from the Yucca Mountain disposal system?
Response: Given we know that accurate prediction of future human activities can not be made, we must also understand that this approach of assuming constancy of the biosphere for projecting radiation-related effects far into the future is the one assumption that we can be assured is incorrect. This can be somewhat mitigated by comparing the expected radiation-related effects under this assumption (including some constrained climate variation, as recommended by the NAS) to a hypothetical biosphere that is constructed based on what appears from the record to be a wetter and cooler climate than the essentially extreme dry climate of today. Given the inherent uncertainties in calculating radiation-related effects, the differences may not be of large significance, but this comparison is one that should be evaluated and applied in place of the assumption of current conditions prevailing.
A more important and necessary mitigation of this known incorrect assumption regarding constancy in the biosphere lies in the choice of the lifestyle of the reference exposed person(s), and the location of the reference exposed person(s) relative to radionuclides released and transported from the repository. The reference exposed individual should be a weighted age/gender composite subsistence farmer, living at or near the boundary of the repository. (See our responses to Questions 3 and 6.) If this reference person is protected by the standard, it is likely that all other individuals will be protected, with two possible exceptions. The first would be people who are the direct, inadvertent intruders of the repository. The second (which could be important if the compliance period extends to the time of peak dose, as we have recommended) would be people who might live or carry out activities at or near Franklin Lake Playa, a largely evaporative surface discharge area of the ground water that flows beneath Yucca Mountain. The potential exposure of this second group should be assessed and if the calculated all pathways dose approaches, or exceeds that of the subsistence farmer, this scenario should receive regulatory attention. The concern is that reconcentration of radionuclides will occur in this playa due to evaporation and evapotranspiration, and the radionuclides will then become a significant source of inhalation and direct doses.
6. In determining the location of the RMEI, we considered three geographic subareas and their associated characteristics. Are there other reasonable methods or factors which we could use to change the conclusions we reached regarding the location of the RMEI? For example, should we require an assumption that for thousands of years into the future people will live only in the same locations that people do today? Please include your rationale for your suggestions.
Response: Our position is that the Proposed Rule should be at least consistent with 40 CFR 191 in this respect. The safety goal is to reasonably protect the RMEI, which we have suggested should be a subsistence farmer (see our response to Question 3) from the maximum projected doses resulting from releases from the repository, whenever it might occur (see our response to Question 8) and wherever it might occur outside the waste emplacement area. This supports the assumption that if this person is reasonably protected, the population is also reasonably protected.
Given the uncertainties in the evolving groundwater flow and transport models and the likelihood that considerable uncertainties will remain with whatever conceptual models are finally used in performance assessment, it is important to calculate potential doses based on differing flow and transport models and variations of flow paths associated with each. While the 5 km boundary of the controlled area is a reasonable limit that should be adhered to in principle, if the flow paths are such that the RMEI could not sustain himself at that location due to topography and lack of soil, the dose at the nearest realistic location on a contaminated flow path should be calculated. Depth to groundwater should not be a consideration in determining the location since just as future human activities can not be predicted, neither can future economic imperatives, considering the groundwater levels at the site. The requirement is to locate the RMEI and the point of compliance at the reasonable location nearest to the waste, at which that person could experience the maximum projected doses from releases from the repository.
Consistent with our recommendation that the RMEI is a subsistence farmer at or near the 5 km boundary of the controlled area, the representative volume of ground water then would be drawn from the fractures of the tuff aquifer, rather than from the downgradient alluvial aquifer. The volume would be relatively small, probably not exceeding 100 to 120 acre feet per year, and it would all be drawn from the contaminated plume, without dilution by uncontaminated water due to pumping water. The "slice of the plume" method for delineating the representative volume would be appropriate under these circumstances.
It is not reasonable to assume that for even hundreds of years into the future that people will continue to live only where people live today. The very limited availability of private land in Amargosa Valley largely has determined where people live and farm today. In the context of United States, or even Nevada state history, not withstanding the future requirements of a nuclear waste repository, requiring such an assumption fails any test of credibility.
7. The NAS suggested using an NIR [Negligible Incremental Risk] level to dismiss from consideration extremely low, incremental levels of dose to individuals when considering protection of the general public. For somewhat different reasons, we are proposing to rely upon the individual-protection standard to address protection of the general population. Is this approach reasonable in the case of Yucca Mountain? If not, what is an alternative, implementable method to address collective dose and the protection of the general population?
Response: Yes, without elaboration.
8. Is our rationale for the period of compliance reasonable in light of the NAS recommendations?
Response: No. We believe that a standard for a Yucca Mountain repository must include a period of compliance that extends to the time of projected peak dose to the individual. We generally support, without further elaboration, the rationale of the NAS on this matter.
We recognize that this position is inconsistent with the 10,000 year compliance period of 40 CFR Part 191 that applies to WIPP. But we also see this as one of the few areas in which it is appropriate that a standard specific to a Yucca Mountain repository differ from that applied to WIPP. While 40 CFR 191 is intended to be a general standard for geologic repositories (and the currently proposed standard has been directed to be specific to Yucca Mountain), the effect of this inconsistency will not result in a precedent for future repositories since it is highly unlikely that another geologic repository will be proposed in the U.S. in the foreseeable future to which 40 CFR Part 191 would be applied.
This inconsistency is appropriate because, with a Yucca Mountain nuclear waste repository, the primary concern is protection of the quality of the potable water supply that would be impacted by releases of radionuclides from the repository, and protection of the people and environment that depend on that water supply. This is not the case with WIPP. At WIPP, a large and sustainable water supply is not directly at risk, as it would be from a Yucca Mountain repository.
Also, WIPP's waste isolation performance depends upon the continued long-term integrity of the existing natural geologic barrier system. Yucca Mountain repository system waste isolation performance, as we understand it, would rely heavily on the projected longevity of an engineered barrier system. As the progressive rate of engineered barrier failure increases, so would releases of radionuclides to the ground water supply, and thus the environment.
After early decay of the major fission products in the waste (within the first few hundred to 1,000 years after repository closure) the time of expected peak dose to the individual is almost entirely dependent upon the rate of failure of the engineered barrier system. Based upon DOE's current performance assessments, after decay of the major fission products, the expected magnitude of the peak dose does not vary greatly over a period of a few hundred thousand years. But the time of peak dose does vary over this range, because it is controlled almost entirely by the projected failure rate of the engineered barrier.
DOE expects few, if any, waste package failures in the first 10,000 years after repository closure, but this projection is accompanied by a broad range of uncertainty associated, with the current engineered barrier design, the amount and chemical nature of water contacting the waste packages, and the assumed number of juvenile failures of waste containers. All of these uncertainties are not likely to be significantly reduced at the time this rule (40 CFR Part 197) is applied. The uncertainty associated with Yucca Mountain's natural barrier system performance and radionuclide transport into and through the biosphere is also broad, but this uncertainty only relates to the magnitude of the projected individual dose, even when viewed on a scale of as little as hundreds of years after repository closure.
The safety issue for a Yucca Mountain geologic repository system is the magnitude of the peak expected dose from radionuclide releases, not when that event occurs. The uncertainty of when it would occur is such that there is no rational basis to truncate the performance calculation at an arbitrary point in time, since at some unknown and unknowable point in the future the peak dose will occur. If it possibly occurs more than 10,000 years after closure, it is still a safety issue to be reviewed in the regulatory arena, not a policy issue to be considered by decision-makers in DOE's Yucca Mountain Environmental Impact Statement, as proposed in this rulemaking.
In response to the regulatory dilemma posed in the commentary for the Proposed rule, if the projected peak dose, at whatever time it might occur, is accompanied by an uncertainty range of 5 orders of magnitude around the standard, there should be no compliance dilemma at all. The repository license application should be rejected.
9. Does our requirement that DOE and NRC determine compliance with 197.20 based upon the mean of the distribution of the highest doses resulting from the performance assessment adequately address uncertainties associated with performance assessments?
Response: This appears to be a reasonable approach that has more basis in scientific precedent than the "expected dose" approach currently used by DOE.
10. Is the single-borehole scenario a reasonable approach to judge the resilience of the Yucca Mountain disposal system following human intrusion? Are there other reasonable scenarios which we should consider, for example, using the probability of drilling through a waste package based upon the area of the package versus the area of the repository footprint or drilling through an emplacement drift but not through a waste package? Why would your suggested scenario(s) be a better measure of the resilience of the Yucca Mountain disposal system than the proposed scenario?
Response: If the objective of the stylized single-borehole scenario, based on drilling a water well, is to test the resilience of the system following human intrusion, then the scenario first should assume waste package penetration without regard for the resistance of the container. Assumptions about the container are only based on current DOE designs, which have changed considerably over time and likely will again. Not many years ago, the waste package was considered to be only "cosmetic."
It is the site resiliency that should be tested as the object of the scenario, not the "evolving" DOE waste package design, which is subject to change even after licensing. For example, this could happen when the high cost of the waste package is considered an unnecessary burden. If a relatively thin ceramic waste container were used, would it resist a drill bit the same way as a heavy metallic container? Second, the scenario should include more than one borehole drilled after loss of institutional control (at repository closure). If people are there and drilling for water, it is not unreasonable that there would be a loss of memory about problems that may arise from a driller intercepting a waste package. A more reasonable scenario would be a borehole intercepting a waste package about every 100 years for a period of the first 1,000 years after loss of institutional controls. If there are people there, and they know water is there - and they need the water, they will drill for it. But, from a performance perspective, there must be special protection against exposure to radionuclides released to the environment during the first 1,000 years after repository closure. Our proposed intrusion scenario is sensitive to both the short (up to 1,000 year) and long-term performance requirements of a repository.
11. Is it reasonable to expect that the risks to future generations be no greater than the risks judged acceptable today?
Response: Yes, but including the notion that risk levels judged today to be acceptable for future generations result from a proportionate weighting of the level of uncertainty associated with future risk projections and the level of uncertainty associated with risks judged acceptable today. In other words, it seems fair that the dose conversion used to calculate risk to future generations should reflect the greater level of uncertainty associated with future dose projections than is associated with risk calculations performed for the current generation.
12. What approach is appropriate for modeling the ground water flow system downgradient from Yucca Mountain at the scale (many kilometers to tens of kilometers) necessary for dose assessments given the inherent limitations of characterizing the area? Is it reasonable to assume that there will be some degree of mixing with uncontaminated ground water along the radionuclide travel paths from the repository?
Response: Yes, it is reasonable to assume there will be some degree of mixing but, from recent work, it appears the flowpaths beneath the repository will be along fractures, with the water moving generally to the south and southeast until it discharges from the tuff into the alluvial aquifer. This suggests that mixing will be limited for the first 15 to 20 km from the repository area, and probably negligible over the first few kilometers. In the alluvial aquifer, it is still likely to be channeled, rather than exhibiting the "bathtub" effect first postulated.
13. Which approach for protecting ground water in the vicinity of Yucca Mountain is the most reasonable? Is there another approach which would be preferable and reasonably implementable? If so, please explain the approach, why it is preferable, and how it could be implemented.
Response: It is most reasonable that groundwater in the vicinity of Yucca Mountain be protected to the same level that currently applies to drinking water throughout the nation. It is not reasonable to expect that an activity will be acceptable if it will contaminate ground water to the extent that treatment might be required before it meets safe drinking water standards. Prevention of contamination now is the reasonable choice, if the clear alternative is the prospect of the need for remediation later.
14. Is the 10,000-year compliance period for protecting the RMEI and ground water reasonable or should we extend the period to the time of peak dose? If we extend it, how should the NRC reasonably implement the standards while recognizing the nature of the uncertainties involved in projecting the performance of the disposal system over potentially extremely long periods?
Response: See our response to Question 8, inclusive.
15. As noted by NAS, some countries have individual-protection limits higher than we have proposed. In addition, other Federal authorities have suggested higher individual-dose limits with no separate protection of ground water. Therefore, we request comment upon the use of an annual CEDE of 25 mrem with no separate ground water protection, including the consistency of such a limit with our ground water protection policy.
Response: See our response to Question 13, inclusive, and Question 8, in part. Regarding an annual individual-dose limit of 25 mrem, we believe, as stated above that this Proposed Rule should be consistent with 40 CFR Part 191, which applies to WIPP in the matter of the dose limit.
We note that the term annual committed effective dose equivalent (Annual CEDE) is correctly used in the Proposed Rule, but in the rule commentary (especially in Section III.A and III.B.) and EPA reference materials, it is sometimes incorrectly used interchangeably with CEDE/year. This should be corrected.
It should also be noted that some countries have individual-protection limits lower than EPA has proposed.
16. We are proposing to require, in the individual-protection standard, that DOE must project the disposal system's performance after 10,000 years. Are the specified uses of the projections appropriate and adequate?
Response: No. See our response to Question 8, at end.
Given the broad range of substantive options and alternatives provided in this Proposed Rule, the EPA after reviewing the comments submitted during the Comment Period, should consider issuing a comment summary document in order to inform interested parties of its progress in developing a Final Rule that is responsive to the comments received.
We appreciate the opportunity to comment on this Proposed Rule, Environmental Radiation Protection Standards for Yucca Mountain, Nevada, 40 CFR Part 197.
Robert R. Loux