Reader's Note:  The following report was prepared by the Nevada Agency for Nuclear Projects in November, 1998 from research findings generated as a result of Agency independent studies addressing key technical and site suitability issues associated with the proposed Yucca Mountain high-level nuclear waste repository site. The report served as the basis for a December 4, 1998 letter from Governor Bob Miller and Governor-elect Kenny Guinn to Sectretary of Energy urging that Yucca Mountain be disqualified as a reporitory site.


Post-closure Geohydrology Disqualifies the Site

The discovery of atmospheric nuclear bomb-pulse chlorine-36 in fracture coatings in and below the Exploratory Studies Facility at the Yucca Mountain site has provided convincing evidence that infiltrating fluid moves rapidly through fractures in Yucca Mountain from the ground surface to the water table. This is in direct conflict with the DOE's original unsaturated zone flow model and has caused the DOE to change its model from one depicting flow dominated by very slow movement through the rock pores to one in which rapid fracture flow dominates. The State has been advocating and developing such a model for a number of years and, as a result has determined that the Yucca Mountain site cannot meet the groundwater travel time requirements of the DOE's Part 960 siting guidelines and NRC's licensing rule, 10 CFR Part 60.

The Guidelines for site recommendation state: "A site shall be disqualified at any time during the siting process if the evidence supports a finding by the DOE that a disqualifying condition exists or the qualifying condition of any system or technical guideline cannot be met." 10 CFR Part 960.3-1-5.

The Post-Closure Geohydrology Disqualifying Condition states: "A site shall be disqualified if the pre-waste emplacement ground-water travel time from the disturbed zone to the accessible environment is expected to be less than 1,000 years along any pathway of likely and significant radionuclide travel." 960.4-2-1. The Qualifying Condition states that the site must permit compliance with the requirements of NRC's Part 60 licensing rule. The NRC's groundwater travel time requirement is that "The pre-waste emplacement groundwater 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 Commission." 10 CFR Part 60.113. The Commission has not approved or specified any groundwater travel time requirement other than 1,000 years.

The chlorine-36 data indicate that the groundwater travel time through the fractured unsaturated zone of Yucca Mountain can be as little as 50 years and probably much less from the underground repository disturbed zone to the water table. The DOE total system performance assessment agrees with the fast travel time and further acknowledges that the fractures are "likely and significant" radionuclide pathways. An April 23, 1998 DOE presentation to the Nuclear Waste Technical Review Board stated in regard to the unsaturated zone, "Long-term average climate travel times are less than 1,000 years to the water table for unretarded [radionuclide] species."

Travel time to the accessible environment in the saturated zone, once the infiltrating water reaches the water table is also rapid. This travel time has been modeled for an accessible environment boundary at a distance of 5 km from the disturbed zone (from the original EPA standard, 40 CFR Part 191), and at 20 km (DOE's current interim standard). Using the longer 20 km (12 mile) distance, DOE's uncertainty analysis of its Total System Performance Assessment (presented June 24, 1998 to the Nuclear Waste Technical Review Board) indicates that travel time in the saturated zone can be as little as about 500 years.

State researchers also have modeled groundwater travel time in the saturated zone. Using what they consider to be more realistic parameter values than those used by DOE for infiltration and flux and using water temperature differences as an indicator of flow, they find the maximum 20 km ground water travel time in the saturated zone to be on the order of 100 years.

In either case, it is evident that groundwater travel time, as defined in the DOE's siting guidelines and the NRC's repository licensing rule, is less than 1,000 years - a condition that requires that the site be disqualified under DOE's site recommendation guidelines.

The Site Recommendation Guidelines (10 CFR Part 960) constitute the technical criteria by which the Secretary determines whether a proposed repository site is suitable for development as a repository, according to the Nuclear Waste Policy Act. The Act further requires, "If the Secretary at any time determines the Yucca Mountain site to be unsuitable for development as a repository, the Secretary shall (A) terminate all site characterization activities at such site..." (emphasis added.) With the current knowledge and demonstration that the Yucca Mountain site meets the Guidelines' post-closure geohydrology condition for disqualification, it is the Secretary's duty now to find the site unsuitable for development as a repository and terminate all site characterization activities.

Fault and Earthquake Hazard

A key health and safety issue at the Yucca Mountain site is the effect of earthquake- induced vibratory ground motion and fault movement during the decades-long operational phase of the repository and the 10,000 or more years after closure of the facility. Seismic events, individually or cumulatively, have the potential to compromise in unpredictable ways the integrity of the engineered barrier system (waste containers, backfill, seals, etc.), the surface facilities for handling and packaging the radioactive waste (storage and transfer pools, etc.), and perhaps most important, the natural barriers of the site (through changes in site geology and hydrology) during the hazardous lifetime of the waste.

State researchers have concluded that a magnitude 6.5 to 7.0 earthquake is likely in the vicinity of Yucca Mountain in the next 10,000 years. Of the 33 known Quaternary faults (less than 2 million years old) in the vicinity of the site, at least five contain observed volcanic ash that provides evidence of contemporaneous volcanic eruption at the young Lathrop Wells volcano 9 miles south of the site with fault rupture events at the site. A recognized characteristic of Great Basin faulting events is that all ground surface fault ruptures are the result of earthquakes with a magnitude of at least 6.0 - 6.5.

During the period of historical earthquake record for southern Nevada, 1868 to present, there have been approximately 250,000 earthquakes in the region with magnitudes ranging from less than 1.0 to 7.8. In the 20-year period, 1976-1996, there have been 621 seismic events with a Magnitude 2.5 or greater, within 50 miles of Yucca Mountain. A Magnitude 3.6 earthquake was recorded in 1948 on a fault on the southeast boundary of the site. The most notable event was the June 29, 1992 Magnitude 5.6 Little Skull Mountain earthquake on a previously unrecognized fault, that occurred 12 miles from the site. This earthquake, along with a number of others in the western U.S. at the same time, is considered to have been triggered by the Magnitude 7.4 Landers earthquake in southern California.

Earthquake and active fault studies provide information necessary to define the regional tectonic framework of Yucca Mountain and the deep geologic structure beneath the site. There is considerable scientific debate over which of a number of possible tectonic models best represents the site area, and because of recognized uncertainties and gaps in regional knowledge, the debate is likely to remain unresolved. A regional model incorporates knowledge of deformational processes, hydrologic processes, and volcanic processes that have operated in the past and are operating at present. Recent independent investigation suggests that the rate of ground deformation in the Yucca Mountain area is about 20 times greater than Yucca Mountain Project investigators had previously determined. If correct, this has potential implications of increased frequency and magnitude for future seismic and volcanic events. Further independent work on surface deformation is in progress.

A credible and generally agreed upon regional tectonic model is important in determining Yucca Mountain site suitability and is a matter of concern in the licensing rules. Major factors that affect the ongoing debate, some of which cannot be mitigated in the near-term, are as follows: 1) the absence of good quality geophysical records to determine subsurface geologic structure and stratigraphic relationships; 2) incomplete stratigraphic succession of Quaternary deposits in the Yucca Mountain area and the lack of appropriate materials for accurate and consistent age determinations; 3) lack of earthquake ground motion data for events greater than magnitude 6.0 at Yucca Mountain; 4) lack of adequate geochronological data to constrain earthquake and fault displacement recurrence rates; and 5) the absence of direct correlation evidence of earthquake events and fault displacement events.

Volcanic Hazard

Future volcanic disruption of the Yucca Mountain site is a critical concern relative to the safety of a Yucca Mountain repository. Volcanoes occur when magma (molten rock formed beneath the earth's crust) intrudes into the crust and flows out onto the earth surface. Earthquakes, fault movement, and hydrothermal activity including hot springs are some of the geologic effects caused by intrusive volcanic activity. The earth's crust is known to be relatively thin in the Yucca Mountain region, and volcanism has occurred in the region for about the last 12 million years.

There is a continuing dispute among Yucca Mountain Project scientists, NRC scientists, and State scientists about the probability of future volcanic disruption of a Yucca Mountain repository. The probability of volcanic disruption estimated by State and NRC scientists is two to three orders of magnitude greater than that estimated by Project scientists. Even relatively small differences in the projected probability of volcanic disruption of the repository result in significant differences in calculated individual doses and risk in the repository performance assessment. According to State scientists, a volcanic eruption in the Yucca Mountain area is probable during the design life of the repository, although the location of the future activity cannot accurately be predicted. In contrast, Project scientists say that the probability of volcanic disruption of the repository is so low (because of disputed interpretations of the area geology) that the risk should be dismissed from consideration in a Yucca Mountain performance assessment. Efforts to resolve the controversy continue to fail, primarily because of a lack of sufficient information, especially in the unresolved matter of the regional tectonic model discussed above. It is unlikely that this dispute that affects any suitability determination and compliance with licensing rules can be resolved in the near term for reasons described above.

Potential for Future Human Intrusion of the Site

The greatest area of uncertainty in assessing the suitability of the Yucca Mountain site for a high-level nuclear waste repository may be the potential for human intrusion of the site during exploration for valuable natural resources. The EPA, NRC, and DOE in their regulations have all recognized the issue and its inherent uncertainty by stating that geologic disposal sites should be selected to avoid locations where resources have been mined, or where it is reasonable to expect future exploration for valuable natural resources.

Nevada researchers have shown that "indicator" minerals suggesting the presence of precious metals (eg. silver and gold) that could attract future exploration activities, such as drilling, are found at Yucca Mountain. Trace amounts of these metals also have been detected in some project core samples. This evidence suggests that the potential for valuable mineral resources in the immediate vicinity of Yucca Mountain must be recognized along with the potential for human intrusion and resultant repository disturbance.

The mining of base and precious metals has been important in Nevada's history and remains so at present. Numerous Nevada ore deposits show common features, and many of these features exist in the Yucca Mountain area. They include certain types of hydrothermal rock alteration and distinctive geochemical signature minerals and suites of minerals. In addition, stratigraphic studies show that the same volcanic tuffs that form Yucca Mountain have hosted significant gold and silver production in the vicinity of Yucca Mountain. Some of these deposits were only recently discovered and mined due to advances in exploration and extraction technology.

The potential for petroleum resources at and near the Yucca Mountain site is currently unknown, but it could also be a factor in future human intrusion. Nevada researchers have found rock known to be a hydrocarbon source rock elsewhere in the State in the vicinity of Yucca Mountain. This rock, the Eleana Formation, crops out in the Calico Hills northeast of the site and at Bare Mountain west of the site. The only Project borehole that has penetrated through the tuff at the site, UE-25 p-1, was not drilled deep enough to encounter the Eleana Formation, if it is present. Aeromagnetic survey interpretations from the Yucca Mountain area suggest the Eleana Formation is present at depth, however, recent seismic geophysical surveys did not permit differentiation of the Eleana Formation from other rock strata beneath the Yucca Mountain tuffs.

All of the millions of barrels of oil produced in Nevada, beginning in 1954, were discovered along the Sevier/Laramide Thrust Belt. Yucca Mountain is located near the southern end of this Belt. Thrust faults, which serve as hydrocarbon traps in other areas, occur at Bare Mountain and in the Eleana Range on the NTS and are postulated in regional geologic models to occur beneath Yucca Mountain. Only deep drilling can verify the presence or absence of hydrocarbon deposits beneath Yucca Mountain. Samples from the Eleana Range and from two wildcat hydrocarbon exploration wells in Amargosa Valley that were drilled in 1991 south of Yucca Mountain, indicate thermal maturation conditions conducive to oil generation, which could encourage further exploratory drilling at and near Yucca Mountain. Such drilling could disrupt the performance of a Yucca Mountain repository.

The current DOE approach to total system performance assessment does not consider potential human intrusion, because the probability of its taking place cannot be estimated. Instead, because it is known that the site has the potential to attract intrusion, an intrusion scenario is assumed and its consequences in terms of radiation dose to an individual are calculated in a separate analysis. Such a calculation is subject to large uncertainty resulting from the uncertainty in establishing the scope of the intrusion scenario, i.e. how many intrusions, how many and which waste packages are affected, exactly where are the intrusions and what geologic features important to repository performance do they penetrate, etc.

It is clear that although certain characteristics of Yucca Mountain and the surrounding area make it attractive for future intrusion through exploration for natural resource deposits, the actual effects of intrusive exploration on repository performance cannot be known. It is also clear that the effectiveness of any future controls that might prevent future human intrusion of the site cannot be known. Despite the language of the Guidelines' Natural Resources Disqualifying Condition (10 CFR Part 960.4-2-8-1) not being exactly applicable, this irreducible uncertainty, alone, is sufficient reason to remove the Yucca Mountain site from consideration for development as a repository. This condition exists for the site regardless of the method selected to assess future repository performance.


Any program with the scope, magnitude, and duration of the federal high-level nuclear waste program, and especially one with the uncertainties of this first-of-a-kind undertaking, should be continually evaluated as to its feasibility. Key to this evaluation is an analysis of the costs to carry the program to completion and whether projected revenues are sufficient to meet the cost of the program's implementation.

The Nuclear Waste Policy Act requires the DOE to "estimate, on an annual basis,...the costs required to construct and operate the repositories to be needed...and to carry out any other activities under this Act" and to "evaluate whether collection of the fee [authorized by the Act] will provide sufficient revenues to offset the costs..." (Sections 301(a) and 302(a)). These requirements are generally referred to as the analysis of "total system life cycle costs" (TSLCC) and the Fee Adequacy Assessment.

During the nearly 16 years that the Nuclear Waste Policy Act has been in effect, DOE has reported three times on projected costs and fee adequacy. The 1986 report estimated TSLCC for a program, using a single repository in tuff at Yucca Mountain, to be $30 billion; the 1990 estimate was $33.5 billion; and the 1995 TSLCC reported an estimate of $34 billion (all in constant 1996 dollars). In each instance, the 1 mil per kw fee collected from the users of electricity generated by nuclear power plants was found to be adequate and not in need of adjustment as provided for by the Act.

The State recently commissioned a cost and projected revenue estimate for the repository program. It was intended to be a means of better understanding the financial implications of the DOE's reference repository design, overall program plan, the recurring congressional bills that would revise the Nuclear Waste Policy Act to provide federal centralized interim waste storage at the Nevada Test Site beginning in 2003, and recent federal court rulings regarding DOE's contractual obligation to begin accepting spent nuclear fuel from commercial reactors in 1998. The report, titled "An Independent Cost Assessment of the Nation's High-Level Nuclear Waste Program", February 1998, was prepared by independent analysts familiar with the program, and includes a review of the analysis by a major national accounting and audit firm.

The total system life cycle cost, including previous repository program expenditures of $6.1 billion from FY 83 through FY 96, is estimated in this analysis to be $53.9 billion (in 1996 constant dollars). The components of this estimate of future costs for the described waste management and disposal system include the following:

Onsite (at reactor) Storage: $4.3 billion (reimbursable costs due to delays in beginning waste acceptance);

Cross-Country Transportation: $6.0 Billion;

Transportation in Nevada: $3.2 Billion (including rail line construction;

Centralized Storage Facility: $9.2 Billion;

Yucca Mountain Geologic Repository: $23.0 Billion;

Other Development and Evaluation Costs: $0.4 Billion;

Other Program Costs: $1.7 Billion.

The projected total program cost from FY 1997 through 2017 is $47.8 billion - $19.1 billion (or 66.8%) greater than DOE's estimate for the same period.

DOE's 1995 estimate of the total 1 mil per kw fee payments is that such payments will provide a revenue base of $28.1 billion (in 1996 constant dollars). Therefore, at a total program cost of $53.9 billion, the general taxpayer liability is $25.8 billion, or about half (48%) of the total estimated program cost. In contrast, only about 10 percent of the waste planned for disposal in a Yucca Mountain repository is considered a taxpayer responsibility, since it will be coming from federally owned, rather than commercial facilities.

The implication of this cost-revenue analysis is that the cost of the program, even without allowing for potentially costly uncertainties, and the liability for the general taxpayer are substantially greater than have been previously estimated. And, the Nuclear Waste Fund under its current fee structure will not meet its share of the program costs.

The report notes that, although DOE's waste management program is in its 15th year, only 11.3 percent of the estimated total system life cycle cost has been incurred through FY 96; 88.7 percent will be incurred in future years. Thus, despite the investments at Yucca Mountain and other sites investigated through 1987, just over 10 percent of the costs that the nation should expect to pay for the currently planned high-level nuclear waste management and disposal program have been "sunk." The report concludes: "In determining future directions for the program, sunk costs should be relegated to a lesser role than they seem to have been in many policy determinations to this point."


Studies of Yucca Mountain began in 1977 after the U.S. General Accounting Office recommended that potential geologic repository sites at government-owned atomic energy defense facilities be included among locations being investigated as potential nuclear waste repository sites. Yucca Mountain is actually not on the Nevada Test Site (NTS), but is immediately adjacent to the western boundary of NTS, on lands under the jurisdiction of the Bureau of Land Management and the United States Air Force. The Western Shoshone Indian Nation also claims Yucca Mountain and the NTS area as part of its much larger treaty lands that have never been ceded to the U.S. government. If the Yucca Mountain site is finally selected for the nation's high-level nuclear waste repository, the site will need to be permanently withdrawn by Congress for that purpose, and the treaty dispute will need to be resolved in order for the government to demonstrate full ownership and control over the repository site, as required by the rules of the Nuclear Regulatory Commission.

After passage of the Nuclear Waste Policy Act of 1982, Yucca Mountain was named one of nine Potentially Acceptable Sites to be studied prior to selection of three candidate repository sites. The Yucca Mountain site is in bedded volcanic tuff. The other sites were at the Department of Energy's Washington State Hanford reservation, in basalt; in Texas and Utah, in deeply buried salt beds; and in Louisiana and Mississippi, in buried salt domes. With DOE's promulgation of its site recommendation guidelines (10 CFR Part 960), pursuant to the NWPA, it was clear that the Yucca Mountain site, the Hanford site, and one salt site would be the three candidates selected for detailed site characterization, unless Yucca Mountain or Hanford were disqualified for technical reasons under DOE's guidelines. This resulted from the guidelines' requirement that the three candidate sites represent a diversity of geohydrologic settings and rock types.

The NWPA required that the Nuclear Regulatory Commission concur in DOE's site recommendation guidelines, which it did in 1984, with the added requirement that "engineered barriers cannot constitute a compensating measure for deficiencies in the geologic media during site screening." This reflects the NWPA specification that geologic considerations are to be the primary criteria in repository site selection.

Also, as required by the NWPA, the Commission promulgated a licensing rule (10 CFR Part 60) for the disposal of high-level radioactive wastes in geologic repositories, and the Environmental Protection Agency, as required, promulgated the mandated "generally applicable standards for protection of the general environment from offsite releases from radioactive material in repositories" (40 CFR Part 191).

In 1986, as directed by the Nuclear Waste Policy Act, five of the original nine Potentially Acceptable Sites were nominated as Candidate Repository Sites, and from these three Candidate sites were selected for detailed site characterization. As expected, the diversity requirement of the site selection guidelines prevailed over strict ranking relative to technical guidelines and the Yucca Mountain and Hanford sites were named as repository candidate sites along with the bedded salt site in Deaf Smith County, Texas.


In 1987, with political difficulties from affected states, schedule slippages, and rapidly escalating costs overwhelming the DOE's site investigation process, Congress was reconsidering the effectiveness of the 1982 Act. A Senate bill under consideration required only one, rather than three candidate sites to be characterized, and halted the screening for a second repository site. In a June, 1987 Senate hearing the DOE manager for the Yucca Mountain Project was asked about his level of confidence that the Yucca Mountain site would be found suitable for development as a repository. His response was the following:

"If one takes the information we have now, and tries to project the kinds of things that are liable to be discovered in the next five or six years of site characterization, it is inconceivable to me that we would discover something of a major nature that would cause us to change our mind about it...The process of doing the modeling and the calculations that estimate the radioactive releases from the repository tells us that we may be five orders of magnitude below a very conservative EPA standard."

The confidence expressed in this testimony, in part, was what led Congress, in 1987, to name Yucca Mountain as the only site to be characterized for a repository and to defer considering the need for a second repository until late in the first decade of the 21st century.

However, by 1992, it was widely apparent that the Yucca Mountain site could not meet the EPA standard's release limit for carbon-14. This radionuclide would be transported and released to the atmosphere above the site in the form of carbon dioxide gas because the proposed waste emplacement location is in fractured rock above the water table, and there are connected fractures in which air circulates into and out of Yucca Mountain. This finding should have resulted in the Energy Secretary's disqualification of the Yucca Mountain site under the provisions of DOE's site recommendation guidelines (10 CFR Part 960).


Instead of disqualifying the site for failure to meet the EPA repository health and safety standard, DOE launched an effort to convince EPA that its standard should be relaxed because, while the carbon-14 releases would violate the standard, the resultant individual dose from the releases would be negligible. This argument ignored the long-term population risk that would result from these carbon-14 releases to the atmosphere.

EPA rejected the request to modify the standard. This ultimately resulted in Congress, in the 1992 Energy Policy Act, directing the EPA to write a new standard specifically for the Yucca Mountain site. The standard was to be one that limited doses to individuals affected by the emplaced waste rather than limiting releases of radionuclides from the repository. Population risk was not mentioned. Congress further directed the Commission to revise its repository licensing rule, as necessary, to be consistent with the new EPA standard.

To date, the EPA has not issued a new proposed Yucca Mountain standard (40 CFR Part 197) for public comment and final promulgation. But the NRC staff, following the direction of the Commission, has recently recommended a site specific repository licensing rule to the Commission for publication as a Proposed Rule for disposal of highly radioactive waste at Yucca Mountain (10 CFR Part 63). The staff recommendation includes a limit on radiation doses from the repository to individuals located 20 kilometers from the repository boundary. The recommendation, also at the direction of the Commission, does not contain a separate groundwater standard limiting annual doses received from the underground source of drinking water. The NRC staff-recommended individual dose limit from the repository is six times greater than the national and State drinking water standard.

Both the Administrator of the EPA and the Governor of Nevada have requested that the Commission defer proposing a licensing rule for Yucca Mountain until an EPA standard is in place, as mandated by the Energy Policy Act of 1992. The duty to set the health and safety standard is clearly placed with the EPA, however the NRC staff recommendation reflects the Commission's desire to impose its own judgement on what that standard should be.

With the mandate for changes in the EPA standard for Yucca Mountain and NRC licensing rule, including individual dose rather than release limits, and the assumption that institutional controls will prevent increased exposures due to post-closure human intrusion of the repository, the DOE has modified the emphasis of its site characterization program.

In DOE's 1988 Site Characterization Plan, which was reviewed and commented on in detail by Nevada scientists, the emphasis was on rigorous study of the Yucca Mountain geohydrologic setting and system as it relates to waste containment and isolation and the need to demonstrate compliance with DOE's 10 CFR Part 960 siting guidelines, NRC's 10 CFR Part 60, and EPA's 40 CFR Part 191. The process was one of identifying specific needed studies, developing detailed study plans, and coordinating the results into a comprehensive understanding of the undisturbed site and setting and the processes and events that have and will likely continue to affect them. The thought at the time was that addition of any engineered barriers was a true representation of "defense in depth," since these barriers would be redundant to the expected natural waste isolation capabilities of the site.

This emphasis on developing a detailed understanding of the site and its setting has since evolved into an exercise that relies less on data collection and more on development of process models and the abstraction of those models into a total system performance assessment, leading eventually to predictions of annual dose to an average individual at some distance from the site and at different times in the future. The waste isolation and containment strategy, now referred to by DOE as the "Repository Safety Strategy" relies on some undefined level of proof (including uncertainty) that four key repository system attributes exist and, functioning together as expected from modeling, will result in acceptable future radionuclide doses to an average individual in the nearby accessible environment. The four key attributes are:

* Limited water contacting the waste packages;

* Long waste package lifetime;

* Slow rate of release of radionuclides from the waste form; and

* Concentration reduction during transport through engineered and natural barriers (eg. diffusion, sorption, and most important, dilution in the groundwater at and below the water table).

This safety strategy relies on engineered barriers to delay the release of radionuclides from the repository through the use of metal waste containers, most of which are projected to remain intact for tens of thousands of years. When the containers fail and radionuclides are released, the reliance shifts to dilution of the radionuclides in the underlying groundwater. Dilution, which constitutes planned pollution of the aquifer, is expected to reduce radionuclide concentrations to an "acceptable" level for individuals 20 kilometers distant from the repository.

Projections of container lifetime and radionuclide dilution in the groundwater are largely based on predictive models with little support from site data. This leads to large uncertainties. Recent DOE presentations on total system performance assessment indicate that uncertainty in expected peak doses resulting from uncertainty in waste package lifetime is greater than a factor of 10,000. The uncertainty factor in peak dose related to uncertainty in dilution ranges from 100 to 10,000.

The redundancy required for "defense in depth" no longer exists. Instead, each of the Safety Strategy attributes must perform as expected in a continuum, or the projected repository system performance will be diminished. Additional engineered features such as backfill tailoring and drip shields over the waste packages have been suggested as providing the needed redundancy to support a "defense in depth" claim.

The NWPA requirement that geologic considerations be primary in repository site selection implements the original and long-held intent that the natural barriers, not the engineered barriers, of a deep geologic repository be the primary defense against loss of waste isolation. The Yucca Mountain site cannot comply with this fundamental intent for geologic waste isolation because a natural characteristic of the site is rapid fluid flow through the potential waste emplacement area to the accessible environment. This factor of the Yucca Mountain site is a further basis for disqualification of the site from consideration for repository development.

In support of its modified site characterization approach, in December, 1996 DOE published notice that it intends to amend its site recommendation guidelines. The specific criteria for compliance and the qualifying and disqualifying conditions would be replaced by the single requirement that a Yucca Mountain repository provide waste containment and isolation in accordance with the yet to be proposed EPA Yucca Mountain standard and NRC regulations implementing that standard. Compliance with the postclosure guidelines would be determined by the result of a total system performance assessment. A Proposed Amendment to 10 CFR Part 960 has not been published for public review and comment.


At the time the Secretary of Energy recommends to the President that a Yucca Mountain repository license application be submitted to the NRC (now scheduled for 2001), based on a finding that the site meets the requirements of the DOE siting guidelines, the NWPA requires that the Commission provide an accompanying report. The report is to be the Commission's "preliminary comments concerning the extent to which the at-depth site characterization analysis and the waste form proposal seem to be sufficient for inclusion" in the application. The NRC staff has identified a number of what it considers to be licensing issues and is preparing Issue Resolution Status Reports based on its review of DOE's on-going work. The Nevada Agency for Nuclear Projects has informed the Commission of its concern that NRC staff issue resolution during site characterization is prejudicial, and despite the admonition in 10 CFR Part 60 that such communication only represents informal conference, the reports may have the effect of closing issues appropriate for consideration in the licensing hearing. In response to this concern, NRC staff has stated that issue resolution only means that the NRC staff currently has no further questions regarding the particular issue. The NRC staff further has said that the reports are to assure that the Commission's preliminary comments regarding sufficiency of information will contain no "surprises" for DOE.

The NRC staff's prelicensing activities and interactions, including review of DOE's ongoing work, is also aimed at assisting the Commission in meeting the NWPA mandate that a decision on whether to grant a construction authorization be made by the end of three years after the repository application is submitted (scheduled by DOE for 2002). The NWPA allows for a one year extension of this period if certain conditions are met. In view of this requirement, as early as 1983, NRC Chairman Palladino warned DOE that, in order for the NRC to comply with this requirement, the repository application must be complete and of high quality when it is first submitted. This admonition has been repeated often during the past 15 years.


The issue of compliance with the NRC required Quality Assurance program for repository licensing has plagued the DOE's Yucca Mountain project since its outset. The current NRC on-site representative continually reports on the numerous quality assurance deficiencies in the site characterization program, pointing out large amounts of unqualified, inaccurate, untraceable, and suspect data being used to support technical assessments and conclusions about projected repository system performance. He points out that much of the project data has been found to be unacceptable and not usable in a license application, adding that the high Quality Assurance deficiency rate has prevailed during the past 10 years of the Yucca Mountain site characterization project with little or no improvement.