ML20209C058
| ML20209C058 | |
| Person / Time | |
|---|---|
| Issue date: | 04/13/1987 |
| From: | Zech L NRC COMMISSION (OCM) |
| To: | Jeanne Johnston SENATE, ENERGY & NATURAL RESOURCES |
| Shared Package | |
| ML20209A941 | List: |
| References | |
| NUDOCS 8704280577 | |
| Download: ML20209C058 (15) | |
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a neau o UNITED STATES y ) , c (f( gg NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 g g '""#,/ ,5
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CHAIRMAN April 13, 1987 The Honorable J. Rennett Johnston, Chairman Committee on Energy and Natural Resources United States Senate Washington, D.C. 20510
Dear Mr. Chairman:
I am responding to your March 10, 1987 letter seeking clarification of the Nuclear Regulatory Commission (NRC) staff ccmments on the Department of Energy's (DGE) final environmental assessments (FEA's) of the notential repository sites.
The NRC staff review of the FEA's and the responses to specific questions which are enclosed are limited to the specific responsibilities of NRC: public health and safety and the waste isolation considerations found in 10 CFR Part 60, NRC regulations for " Disposal of High-Level Radioactive Waste in Geologic Repositories" and the associated 00F Siting Guidelines. In deciding whether to proceed with site characterization, the DOE has considered(e.g.,
responsibility other factors outside NDC's cost, schedule, rankingregulatory of sites ). The NRC staff has not reviewed or commented upon such areas.
- In this context, the NRC staff review of the five FEA's did not identify concerns that would call into question the suitability of any of the five sites for site characterization. While numerous concerns have been identified by NRC staff relative to each site, these concerns are of the nature anticipated at any site for which the existing data base is limited. While these concerns should not disqualify the sites from further testing to determine their suitability for the repository, they are significant with respect to the licensability of each site. The nurpose of site characterization is to develop data to evaluate the validity and significance of such concerns relative to site suitability.
Hence, these concerns need to be addressed as the 00E draws un Site Characterization Plans (SCP's) for each site.
Consequently, there is no reason, based on the NRC staff review of the FEA's and of other materials developed by the DOE and other parties, to delay characterization of the three sites selected by the DOE. The NRC concerns can only be addressed through the site characterization process, i
8704280577 870422 PDR COMMS NRCC CORRESPONDENCE PDR
These general statements are intended to clarify the NRC position on the FEA's and the state of the DOE HLW program. In~ycur letter
! you asked the Commission to respond to twelve questions regarding the nature of the NRC staff comments and how they should be viewed by the DOE and the Committee. The enclosure to this letter contains the NRC responses to those questions. I hope that our specific answers, taken in conjunction with the contents of this letter, will provide the clarification of the NRC's position that you seek.
Commissioner Asselstine does not agree with this response.
Sincerely, M.
Lando W. Z , J r.
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Enclosure:
NRC responses to questions cc: Senator Mark 0. Hatfield s
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QUESTION 1. Have the states accurately characterized the nature and intent of the NRC staff comments?
ANSWER.
The states have focused on many of the same concerns that the NRC staff has raised relative to the FEA's. It is important to provide the context in which the NRC staff comments were presented. In a December 22, 1986 letter transmitting the FEA comments to DOE the staff concluded that "...in each of the final EA's our review identified remaininq concerns which are principally related to 1) not identifying the range of uncertainties associated with the existing limited data base, 2) not identifying the range of alternative interpretations and assumptions that can be reasonably supported by existing data, and 3) not incorporating a reasonable range of uncertainties and alternative interpretations into evaluations and conclusions." The response also stated that "... recognition of these uncertainties and alternative interpretations is critical to the development of test plans that will lead to adequate characterization of sites and result in the information needed for licensing." None of the concerns would call into question the suitability of any of the five sites for site characterization. While numerous concerns have been identified to date relative to each site, these concerns are of the sort anticipated at any site when the existing data base is limited.
While these concerns should not disqualify the sites from further testing to determine their suitability for the repository, they are significant with respect to the licensability of each site if they are not resolved through information gained from site characterization. Hence, these concerns need to be addressed as the DOE draws up an SCP for each site. The purpose of site characterization is to develop data to evaluate the velidity and significance of such concerns relative to site suitability.
Consequently, there is no reason, based on the NRC staff review of the FEA's, to delay characterization of the three sites selected by the 00E. The NRC staff concerns can only be addressed through the site characterization orocess.
QUESTION 2. How serious are the issues identified by the NRC?
ANSWER.
The concerns identified by the NRC staff do not question the
- adequacy of_the sites for site characterization. They are significant with respect to the licensability of the sites if l they are not resolved through information gained during site i characterization. Hence these concerns need to be addressed as 1 the DOE draws up an SCP for each site. The purpose of site characterization is'to develop data to evaluate the validity and significance of such concerns relative to site suitability. Such concerns requiring evaluation through the site characterization process would be expected to exist with respect to any site under consideration for a repository.
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QUESTION 3. Should the Committee be concerned that DOE is
" recklessly" plowing ahead with flawed sites, as the states have charged?
ANSWER.
The DOE has evaluated each site against the Siting Guidelines which, in its concurrence, the Commission considered to address all key areas needing attention in the evaluation of site suitability. In its FEA's the DOE found no disqualifying factors for any of the five sites. The NRC staff's independent review likewise has not identified any disqualifying factors. However, the NRC staff did identify a number of factors, typical of any site with a limited data base, needing to be addressed during site characterization.
It is important to note that the NRC review of the FEA's was limited to the public health and safety and the waste isolation considerations found in 10 CFR Part 60. In deciding whether to proceed with site characterization, the DOE has considered other factors outside the NRC's regulatory responsibility (e.g., cost; schedule; ranking of sites). The NRC has not reviewed or commented upon such areas, i
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QUESTION 4. Do the .NRC staff concerns indicate that D0E.should select other sites for characterization or simply i that. DOE needs to collect more data to evaluate-those sites?
ANSWER.
As explained previously, the NRC staff has not identified any.
, reasons why the three sites selected should not be characterized.
Staff concerns indicate that mora data needs to be collected-during site' characterization in order to find out whether the concerns raised can be satisfactorily resolved. Such concerns
- exist for all nine of the sites that were identified by the DOE in February, 1983 as potentially acceptable sites for a mined geologic repository, and would be expected to exist for any potential site with a limited data base. NRC staff review of the nine draft Environmental Assessments (DEA's) found no disqualifying factors for any site but raised concerns similar to the ones raised relative to the five sites in the NRC staff '
review of the FEA's. Hence it should not be inferred that the concerns expressed by the NRC staff relative to the three sites-selected for site characterization indicate that DOE should select other sites.
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0 QUESTION 5.
~~ Based on the information available today, does.NRC feel there is any reason not to go ahead with site characterization at the sTtes in Nevada, Washington, and Texas?
ANSWER.
The NRC review of the FEA's was based on the public health and
. safety and the waste isolation considerations found in 10 CFR Part 60. On those bases the staff identified no disqualifying factors for-any of the sites and no reason why site characterization should not proceed. In deciding whether to proceed with site characterization, the DOE has considered other factors outside the NRC's regulatory responsi'*lity (e.g., cost; schedule; ranking of sites). The NRC has not eviewed or enmmented upon such areas.
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k OUESTION 6.
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Evaluating DOE's performance to date, does it appear that 00E.is heading in the right direction in its efforts to develop a data base that'wil' be sufficient to support a repository license application?
ANSWER.
There has been a continuous overall improvement in-the DOE program to develop an adequate data base, in particular as demonstrated by resolution in'the final EA's of many of the NRC concerns identified relative to the draft EA's. The March 3-4, 1987 briefing of the NRC staff and the affected states and tribes by the DOE on their issues hierarchy and issue resolution strategy laid out a logical and rigorous way of identifyirg issues and the data needed to resolve them. How the DOE implements the issue resolution strategy is the key to whether they are heading in the right direction. NRC staff review of the SCP's will assess their progress in this area. One early indication that the DOE is progressing in this area is their recognition of the need to conduct key hydrologic testing at the Hanford site prior to construction of the exploratory shaft.
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P QUESTIONS 7-12. Comment on the six technical areas cited by the State of Nevada.
ANSWER.
The State of Nevada has focused on many of the same concerns that the NRC has raised relative to the Yucca Mountain Site FEA.
However, it is again important to provide the context in which the NRC staff comments were presented. No issues were identified during the NRC staff review of the Yucca Mountain Site FEA that call into question the suitability of the Yucca Mountain site for characterization. The concerns identified can be potentially disqualifying with respect to the licensability of the Yucca Mountain site if they are not resolved through information gained from site characterization. The purpose of site characterization is to develop data to evaluate the validity and significance of such concerns relative to site suitability. Hence, these concerns need to be addressed in the SCP for the Yucca Mountain site.
In response to the Committee's request to comment on the six technical areas cited by the State of Nevada, each area is addressed below.
O OVESTION 7.
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Active fault movement and reactivation of prior.
faulting by nuclear nuclear weapons testing.
ANSWER.
As stated in NRC staff comment 1 on the Yucca Mountain Site FEA, available evidence suggests that faults in the vicinity of Yucca Mountain have undergone movement in the last 40,000 years and that some faults in that area have been reactivated by nuclear weapons testing. Fault activity can cause vibratory ground motion. During site characterization the DOE needs to ascertain which of the several different types of faults at and in the vicinity of Yucca Mountain are potentially active and whether the vibratory ground motion and/or movement associated with those faults could disrupt repository construction and operation and impact the waste isolation capabilities of the Yucca Mountain site.
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QUESTION 8. Hydrothermal activity beneath Yucca Mountain which could affect the waste iso!ation capability of the site or any containers used there.
ANSWER.
As stated in NRC staff comment 4 on the Yucca Mountain Site FEA, the presence of calcite-silica vein deposits at several locations at and around Yucca Mountain sugaests the potential for hydrothermal activity in the area. Such activity could open new
- pathways for groundwater and any released radionuclides to reach i
the accessible environment or could enable high-temperature corrosive fluids to come into contact with the waste package, possibly resulting in higher than expected rates of corrosion for the waste package. During site characterization the DOE needs to determine if the veins are of hydrothermal origin and if they are, whether that phenomenon could be a mechanism for radionuclide transport to the accessible environment or a process by which high-temperature corrosive fluids are introduced to the waste package environment.
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e QUESTION 9. The possibility of ore deposits in the area that might cause future human intrusion.
ANSWER.
As stated in NRC staff comment 5 on the Yucca Mountain Site FEA, the limited data base currently available permits as one interpretation that there may be significant economic natural resource potential in the Yucca Mountain area. Should that prove to be true, the possibility exists of economically motivated post-closure human-interference activities that could adversely affect the waste isolation capabilities of the Yucca Mountain site. During site characterization the DOE needs to assess the magnitude of the natural resource potential of the Yucca Mountain area and the significance of any associated potential for future human intrusion.
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b QUESTION 10. DOE's overreliance on the geochemical system to retard radionuclide transport through the rock.
ANSWER.
As stated in NRC comment 8 on the Yucca Mountain Site FEA, the DOE is relying on various radionuclide retardation mechanisms based on properties of the bulk rock and of certain minerals in the rock to substantially diminish radionuclide transport.
However, evidence supporting the effectiveness of these mechanisms is currently not conclusive. If the effectiveness of these mechanisms cannot be demonstrated, credit cannot be taken for these features of the geochemical system at Yucca Mountain in the evaluation of the site's waste isolation capabilities.
During site characterization the DOE needs to pursue field and
' laboratory methods to establish the effectiveness of these mechanisms to retard the transport of radionuclides.
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A QUESTION 11. DOE's overreliance on models of a groundwater travel time in the unsaturated zone.
ANSWER.
As stated in NRC staff comment 7 on the Yucca Mountain Site FEA, The existence of extensive fracturing within the' rocks above the water table (i.e., in the unsaturated zone) at Yucca Mountain could. contribute to significantly faster movement of groundwater to the accessible environment than is currently pro.iected in the.
Yucca Mountain FEA hydrologic model which assumes that matrix flow is dominant. During site characterization the DOE needs to gain a better understanding of the nature and rates of flow in the Yucca Mountain hydrologic systen.
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a QUESTION 12. DOE's overreliance on the uncertain nerformance o' engineering barrier systems.
ANSWER.
In the Yucca Mountain Site FEA, DOE has suggested 3000 years as a conservative estimate for the waste package lifetime (See Answer to #9). Given the current uncertainties in the models and data used to extrapolate to a minimum 3000 year container life, the NRC staff cannot now characterize as either realistic or conservative. Consequently,-during the development of their site characterization and testing plans, the DOE needs.to recognize- ,
the uncertainties in their models and data. DOE should focus their efforts on gathering site and experimental data that decrease the amount of uncertainty in their estimate of waste package lifetime and develop a realistic and defensible value.
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