2. Cumulative Impacts of Spent Nuclear Fuel Transportation

Section Contents

• 2.1 Background on the Proposed HLW Repository
• 2.2 Approach to Analysis
  • 2.2.1 Transportation and Route Scenarios
  • 2.2.2 Analysis of Routes Using the HIGHWAY Model
  • 2.2.3 The RADTRAN Model
• 2.3 Cumulative Health Risks of Spent Fuel Transportation
  • 2.3.1 Radiological Risks
  • 2.3.2 Nonradiological Risks
• 2.4 Cumulative Impacts of Additional Radioactive Waste Shipments
• 2.5 Summary of SNF Transport Impacts
• 2.6 Environmental Justice

The purpose of this analysis is to determine whether the Commission can reach a generic conclusion about the cumulative impacts of spent fuel transport in the vicinity of a repository due to the renewal of a nuclear power plant operating license. If the Commission can reach such a conclusion, the issue can be designated a Category 1 issue and the finding codified in 10 CFR Part 51. For an issue to be designated Category 1, the following criteria must be met:

(1) The environmental impacts associated with the issue have been determined to apply either to all plants or, for some issues, to plants having a specific type of cooling system or other specified plant or site characteristic;

(2) A single significance level (i.e., small, moderate, or large) has been assigned to the impacts (except for collective off site radiological impacts from the fuel cycle and from high level waste and spent fuel disposal⁽¹⁾); and

(3) Mitigation of adverse impacts associated with the issue has been considered in the analysis, and it has been determined that additional plant-specific mitigation measures are likely not to be sufficiently beneficial to warrant implementation.

Section 2.1 is a description of the status of the Yucca Mountain site as a potential geologic repository in order to provide a context for the analysis.⁽²⁾ Section 2.2 describes the approach employed by the NRC staff to analyze the cumulative effects of SNF transport in the vicinity of the proposed repository due to the renewal of a nuclear power plant operating license . Section 2.3 presents the results of those analyses, Section 2.4 discusses impacts of additional radioactive waste shipments, and Section 2.5 presents a summary of SNF transport impacts. Finally, Section 2.6 examines the potential for environmental justice issues related to radioactive waste transport in Clark County, Nevada.

2.1  Background on the Proposed HLW Repository

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The Nuclear Waste Policy Act of 1982 (NWPA) gave the U.S. Department of Energy the responsibility for finding a site for disposal of commercial SNF and other high-level waste, and for building and operating an underground disposal facility called a geologic repository. In 1987, Congress amended the NWPA and directed DOE to study only Yucca Mountain, Nevada, to decide whether it is suitable for a repository for high-level nuclear waste. Under the NWPA, DOE has been studying Yucca Mountain for 15 years as a potential geologic repository for the disposition of the nation's spent nuclear fuel and high-level radioactive waste. However, a number of decisions remain to be made before Yucca Mountain could ever be considered for development of a repository; any one of these decisions can stop the approval process. The Secretary of Energy plans to make a decision in 2001 on whether to recommend the site to the President for development as a repository. If DOE finds the Yucca Mountain site suitable and recommends the site, then the President must decide whether to recommend the site to Congress. If the President recommends the site and if Nevada submits a notice of disapproval, then Congress must decide whether to allow the recommendation of the President to take effect. Only if the decisions remaining to be made ultimately support development of a repository at Yucca Mountain, then DOE would submit a license application to the NRC. If the repository is licensed, then SNF and HLW would be shipped to the site using only NRC-certified transportation packages.

2.2 Approach to Analysis

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The staff's overall approach was to use NRC's current knowledge base and transportation experience, to develop assumptions that reasonably estimate and bound the risks associated with the increased number of spent fuel transports that might occur if license renewal of nuclear power plants were to occur. These assumptions are generic in nature, meaning they could be applied to any licensed nuclear power plant. The NRC staff made a number of 'conservative' assumptions, which means that the assumptions would lead to an overestimate of what the NRC staff believes to be the actual impacts. Examples of where the NRC staff believes conservative assumptions have been used appear later in this section. The goal is for the results to be used by a license renewal applicant as it would any other Category 1 issue.

In accordance with the NWPA, DOE is required to prepare an environmental impact statement (EIS) for Yucca Mountain. The EIS will consider the proposal to construct, operate, and eventually, close a repository at Yucca Mountain. See DOE Notice of Intent (60 FR 40164). DOE is expected to assess national and regional (i.e., within the State of Nevada) transportation options that cover the full range of operating conditions relevant to potential impacts to human health and the environment.⁽³⁾ In its response to public scoping comments, DOE indicated that its draft EIS transportation analysis would include both truck and rail transport, and use Department of Transportation routing regulations and representative routes and actual route characteristics. Thus, DOE's expected transportation analyses will be detailed; however, DOE does not plan to complete its final EIS until 2000. DOE recently issued its draft EIS for a 180-day public comment period beginning on August 13, 1999.

This analysis aims to address the cumulative impacts of SNF transportation to a HLW repository from a generic perspective.⁽⁴⁾ Because Congress , at this time, has directed DOE to study only Yucca Mountain for the proposed repository, the NRC staff began with the assumption that all SNF would be transported through Clark County, Nevada (i.e., the Las Vegas area) en route to the repository. This assumption is conservative in several ways. First, current law would not allow more than 70,000 metric tons of heavy metal (MTHM), with an estimated 63,000 MTHM of that total being from commercial SNF, to be disposed of at Yucca Mountain. Nevertheless, the NRC staff used estimates of quantities of SNF that would need to be disposed of that are considerably larger than the 63,000 MTHM for the purpose of evaluating the entire inventory of SNF produced by nuclear power plants. Second, there are other routes to Yucca Mountain rather than through Clark County, but none of the other routes would encounter as high a population as found in Clark County. The NRC staff also adopted this assumption because--whether Yucca Mountain or another site is selected for a repository-- estimates of transportation impacts are maximized in the case where all SNF is transported through a major metropolitan area. The NRC staff believes it important to emphasize that, while conservative, the assumption may not be at all representative or realistic.

Transportation to Yucca Mountain or another repository site may make heavy use of rail transportation, for example, because rail transport is expected to be less costly than truck transport. The overall radiological impacts of rail as compared to highway shipments may be lower. In part, this is because of the higher capacity of rail cars which allow fewer shipments and because population densities along most rail routes are typically lower than along the interstate highways that trucks would use to transport SNF. Additionally, when non-radiological accident rates between truck and rail shipments are normalized for payload size and mileage, the accident rate for rail shipments is about 3 percent of the comparable accident rate for truck shipments (Dyer and Reich1993). Evaluation of cumulative impacts in the vicinity of Las Vegas carried out in this analysis, therefore, represents an upper bound because it assumes all SNF would move by legal-weight truck rather than by rail or by a combination of rail and truck to reach the repository.⁽⁵⁾ Further, to ensure that the impacts estimated here are conservative, the NRC staff assumed that shipments would be by legal-weight trucks rather than heavy-haul trucks because fewer shipments would be required if heavy-haul trucks were used.

To examine the effects of license renewal, the NRC staff used two estimates of SNF that would be transported to the repository. The first was based on the assumption that no nuclear plants have their licenses renewed, and the second was based on the assumption that all existing nuclear plants would operate for the full duration of a 20-year license renewal period. This means that the amount of SNF shipped for the license renewal case was assumed to be 50 percent greater than the amount of SNF for the no-license renewal case. The assumption used for the license renewal estimate is conservative because some plant owners have already decided not to request renewal of plant operating licenses.

As noted above, the NWPA prohibits DOE from accepting more than 70,000 MTHM of HLW at the Yucca Mountain repository, only 63,000 MTHM of which would be SNF. Based on this limit, DOE estimates on the order of 37,600 truck shipments of SNF to Yucca Mountain, assuming all SNF travels by truck in legal-weight casks (K. Skipper, Yucca Mountain Site Office, personal communication to D. P. Cleary, NRC, July 11, 1997). For this analysis, the NRC staff assumed that all current and committed SNF, about 84,000 MTHM, would be disposed of at Yucca Mountain. [The Nuclear Waste Technical Review Board (1997) made a very similar estimate of current and committed SNF.] Using DOE's estimated number of shipments and the total amount of SNF leads to an estimate of the order of 50,000 truck shipments without license renewal. Assuming all plants renew their licenses and operate for an additional 20 years, the estimate is on the order of 75,000 truck shipments.⁽⁶⁾

The analysis used the RADTRAN computer code (Section 2.2.3) to estimate the radiation doses to the people of Clark County and to transportation workers. The route and population density numbers used by RADTRAN computer code were generated by the HIGHWAY computer code and modified by the NRC staff to account for population growth (Section 2.2.1). The human health implication of the radiological exposures were estimated by use of BEIR V radiation-dose-to-cancer-risk factors (Section 2.2.3). The risk of non-radiological accidents were estimated by using U.S. Department of Transportation statistics (Section 2.3.2).

2.2.1 Transportation and Route Scenarios

The HIGHWAY computer code (Johnson et. al. 1993) was used to select routes. The HIGHWAY computer code models the U.S. highway system. Its data base includes all interstates, most U.S. highways, and many State, county, or local roadways. It represents about 380,000 km [240,000 miles] of roadway. Several different routing options are available in the highway program, including probable commercial routes, routes on the interstate highway system, routes that bypass major urban areas, and preferred routes designated by the States. Additional detailed routing analysis can be performed by blocking individual or sets of highway segments or intersections contained in the data base, a feature the NRC staff utilized to analyze the downtown routes.

The selection of preferred routes assumes that each shipment consists of highway-route-controlled quantities of radioactive materials. Travel time is optimized based on maximum utilization of the interstate highway system, with preference given to bypasses around major cities, except where alternate routes have been designated by state officials. Selected information considered by the NRC staff in using the HIGHWAY computer code is given in Appendix 2. These inputs and outputs provide a detailed listing of each highway route as well as mileage and population density zones considered in the analysis.

A beltway is being constructed in Clark County (Clark County 1997) which is expected to consist of three connected segments including a southern, western, and northern route; these segments will create a freeway "ring" around the Las Vegas Valley to route vehicles around, rather than through, the congested urban core (Figure 1). The southern segment of the beltway is being built in sections, with each segment opening to traffic upon completion. The first phase of the project, from I-15 to McCarran Airport (Airport Connector), was opened in 1994. The second section, from Warm Springs Road to Windmill Lane, opened to traffic in Oct. 1995. In Feb. 1997, the third portion of the project-- from Windmill Lane to Eastern Ave.--became fully operational. The fourth section of the southern beltway, Eastern Ave. to Pecos Road, was completed in 1997.

The proposed northern and western beltway is expected to be a 10-lane facility with adequate right-of-way to permit construction of a fixed guideway facility (e.g., a commuter rail line). This is called the "ultimate facility" and will require a right-of-way width of 107 to 137 m [350 to 450 ft], plus land for interchanges or access to other transportation facilities.

Because the beltway is expected to be complete before the repository begins operation and because regulations require that spent fuel shipments use bypasses where possible, analysis of transportation on the route through downtown on the current interstate system yields higher exposure estimates than might actually occur. In addition, there are two plausible routes into Clark County; from the south on I-15, and from the northeast on I-15. SNF from western and southwestern states would likely arrive via the southern route. SNF from eastern states would likely arrive via the northeastern route. To ensure that the conclusions of this analysis are conservative, the NRC staff analyzed scenarios in which all SNF arrived via the northeastern route and scenarios in which all SNF arrived via the southern route. The combination of the northeastern and southern scenarios, and the downtown and beltway scenarios gives four transportation route scenarios that were analyzed by the NRC staff.

The NRC staff analyzed the potential impacts of SNF transport along the four routes (illustrated in Figure 2). The route named "from the northeast through downtown" starts at the Arizona-Nevada state line and follows I-15 to near downtown Las Vegas and then proceeds northwest on U.S. 95 beyond the northwestern corner of Clark County, Nevada. The route named "from the south through downtown" starts at the California-Nevada state line and proceeds north on I-15 to near downtown Las Vegas and then proceeds northwest on U.S. 95 through the northwestern portion of Clark County. The other routes are similar to the first two except each route will use the I-215 beltway that is currently planned and under construction around the north, west, and southern portions of the Las Vegas metropolitan area. The route named "from the northeast using the beltway" follows I-15 from the

Arizona-Nevada border to the northeastern part of the Las Vegas metropolitan area and then follows the planned I-215 across the northern portion of Las Vegas. In the northwestern part of the Las Vegas metropolitan area, the route exits I-215 and continues northwest on U.S. 95 out of Clark County. The route named "from the south using the beltway" follows I-15 from the California-Nevada border to Las Vegas, near the southwestern corner of the McCarran International Airport and then proceeds west and then north on I-215. At the junction with U.S. 95, the route leaves I-215 and proceeds northwest out of Clark County.

Figure 1 Proposed Las Vegas beltway

Figure A.2 Routes analyzed in this study

2.2.2 Analysis of Routes Using the HIGHWAY Model

The total travel distance, the fraction of travel in each population density zone, and the average population density of each zone are necessary inputs to the RADTRAN computer code. HIGHWAY computer code was run using 1990 census block group data, the latest suitable data available. For each route segment, the HIGHWAY computer code uses the characteristics and populations of the census block to assign the segment to one or more of 12 population density zones. For each route segment, the NRC staff reassigned the route segment to higher population density categories in an attempt to represent future population growth of Clark County. The routing data from the HIGHWAY computer code, which makes use of 12 population density zones, were collapsed into 3 zones (i.e., rural, suburban, and urban) to simplify the analysis performed by the RADTRAN computer code. The results of the process are displayed in Table 1. The columns entitled "1990 population" display the input that the RADTRAN computer code would have considered based on 1990 Census data. The columns entitled "Future population" display the input that was considered using the RADTRAN computer code analysis for this Addendum. The parameters in the "future population" columns are based only on the staff's anticipation of substantial future population growth. Given that SNF shipments would occur over perhaps 40 to 60 years beginning about 2010, forecasting of population densities and highway routes are more reasonable assumptions than relying on the populations reported in the 1990 Census.

2.2.3 The RADTRAN Model

The RADTRAN computer code (Neuhauser 1984, 1992) was used to model the incident-free radiological exposure and the probabilities and consequences of radiological releases resulting from accidents. The incident-free risks are dependent on the radiation dose rate from the shipment, number of shipments, package dimensions, route distance, vehicle speed, and population densities along the travel routes. The accident risks are dependent on the radiological inventory, accident severity, probability of occurrence for each accident category, and the amount of inventory of radioactive material released, aerosolized, and inhaled, as well as the dispersibility of the material based upon the chemical and physical properties. Selected information considered by the NRC staff in using the RADTRAN computer code is given in Appendix 3.

For incident-free transportation, the RADTRAN computer code calculates total body doses for the transport crew and for the general public. The NRC staff assumed that the radiation source is characterized for the analysis by the radiation dose rate at 1 m from the transportation package surface. The regulatory limit found at 49 CFR 173.441 is 0.1 mSv/hour [10 mrem/hour] at 2 m [6.6 ft] from the outer lateral surfaces of the vehicle. The NRC staff assumed 0.13 mSv/hour [13 mrem/hour] at 1 m [3.3 ft] rate because it corresponds to 0.10 mSv/hour [10 mrem/hour] at 2 m [6.6 ft], the regulatory limit. This analysis used the conservative assumption that for all shipments the radiation level would be at exactly the regulatory limit. Based on shipping experience, actual radiation levels are expected to be lower than the regulatory limit level that was assumed in this analysis.

The NRC staff made the conservative assumption that the transport crew consists of four people, two in the cab of the truck and two in an escort vehicle. The NRC staff assumed that each of these persons would be exposed at the 0.02 mSv/hour (2 mrem/hour) regulatory limit (found at 49 CFR 177.842) that applies in the cabs of motor vehicles. The people in the vehicle would realistically be expected to receive substantially less dose than the escort drivers because the occupants of the escort vehicle would be farther from the SNF package than the drivers. The NRC staff also made the conservative assumption that the escort vehicle and its two occupants would accompany the truck the entire time it was in Clark County. This assumption results in the situation where the escort vehicle accompanies the truck for a longer distance than required by NRC. Consequently, these assumptions lead to an overestimate of the doses to the transport crew.

Table 1. Transportation route parameters for RADTRAN analysis

In comments on the draft Addendum 1, the public expressed concerns about radiation doses to truck inspectors at ports of entry and doses to the public during periods when the highways are particularly congested. While there are a number of ways to reduce the magnitude of such exposures, the NRC staff introduced two additional conservative assumptions into the RADTRAN computer code analysis to account for these concerns. First, the NRC staff assumed that the trucks would travel at lower speeds than is typical for interstate highway travel; 55 mph in rural areas, 25 mph in suburban areas, and 15 mph in urban areas. Second, the NRC staff assumed that the trucks made stops at a rate of 0.011 hours/km of travel. Because each truck traveled at least 165.8 km (104 mi), every truck was assumed to stop for at least 1.8 hours (109 minutes). Further, the NRC staff assumed that for the entire stop period, 30 members of the public were located 20 m (66 feet) from the truck, and that all members of the transport crew continued to receive 2 mrem/hour during the stop. As a practical matter, the NRC staff believe that these conditions would seldom be exceeded for an individual shipment, and that typical shipments would move at normal highway speeds throughout the urban and suburban areas, and that shorter, less frequent stops would be the norm.

Each truck shipment of multiple fuel assemblies was modeled as a single package with a homogeneous distribution of the radiological inventory. Both point- and line-source approximations were used based upon the distance between the exposed individuals and the radiation source. The characteristic dimension (known in the RADTRAN computer code as the variable PKGSIZ) is the largest linear dimension of the configuration and is used in the line-source approximation to calculate total dose; 5 m [16.5 ft] was the assumed length of the source. The radiation dose to the public from the casks was assumed to consist entirely of gamma radiation for calculation of the incident-free dose. This assumption is appropriate since the regulatory limits were used and the neutron and gamma radiation is attenuated at nearly identical rates up to about 700 m (2,296 feet) (neutrons are attenuated more rapidly beyond 700 m).

For releases of radioactive material resulting from postulated accidents, the RADTRAN computer code uses a dispersibility category to determine the fractions of the total inventory that are aerosolized and respirable. The analysis reflects the dispersibility category for each isotope and considered the release fractions based on the type of package as a function of accident severity.

Accident risks include acute fatalities and latent risk of fatal cancer (from chronic exposure) for both the current and future generations. The accident risk (expected value of dose from accidents) is the summation of the products of estimated dose for each accident severity category and the associated probability of occurrence for the category. To provide a conservative estimate of potential accident effects, the NRC staff assumed high burnup fuel (62,000 MWd/MTU). Table 2 lists the characteristics of SNF assumed for the accident analysis.

Radiation exposures are reported as collective dose to a population (person-Sv [person-rem]) and the dose to the maximally exposed individual (mSv [mrem]). Health risks from exposure to radiation are reported as estimated lifetime risk of fatal cancer (LRFC) resulting from incident-free transportation of SNF and from highway accidents involving potential radiation releases. Expected fatalities from truck accidents not involving radiation releases are also reported.

A National Academy of Sciences report (NAS 1990, Table 4-2), commonly called the BEIR V report, gives estimates of the number of cancer deaths expected to occur from a continuous exposure of 10 mSv/year [1 rem/year] above background from age 18 until age 65. This value results in a risk factor of 4.0 × 10² LRFC per person-Sv [4.0 × 10⁴ LRFC per person-rem] that is most applicable to occupational exposure. The BEIR V report also estimates the number of cancer deaths expected to occur from a continuous lifetime exposure of 1 mSv/year [100 mrem/year] above background, which results in a risk factor of 5.0 × 10² LRFC per person-Sv [5.0 × 10⁴ LRFC per person-rem] that is most applicable to exposure of the general public. The general public LRFC risk factor is slightly higher than the occupational risk factor because the general public dose is assumed to be experienced by people of all ages while the occupational exposures are assumed to be experienced only by people from age 18 until age 65. Children and adolescents are presumed to be more susceptible to radiation-induced health effects than adults.

Because doses fall off quickly with distance from the route, persons close to the route receive and account for much more of the population dose than those who live some distance from the route. The contributions to population doses from exposure to persons living more than 0.8 km [0.5 mile] from the route is negligible. Thus, the affected population was assumed to be residents of and visitors to Clark County, Nevada within 0.8 km [0.5 mile] of the route assumed to be followed by the trucks transporting SNF.

2.3 Cumulative Health Risks of Spent Fuel Transportation

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Health risks associated with SNF transport include both those associated with radiation exposure and the nonradiological risks associated with the assumed movement of trucks carrying SNF through the Clark County, Nevada area (i.e., traffic accidents).

2.3.1 Radiological Risks

Radiation exposure can occur in two ways--exposure to radiation emitted by the SNF cask during routine (incident-free) transport and exposures in the event of an accident that leads to release of radioactive material . For incident-free transportation, the NRC staff used the RADTRAN computer code to calculate total body doses to the transport crew and the general public. The radiation source is characterized for the RADTRAN computer code by the radiation dose rate at 1 m from the package surface.

Potential radiological accident effects include both acute fatalities resulting from very high radiation exposure (that might occur in the unlikely event of failure of an SNF shipping container or cask), and the LRFC resulting from radiation exposure that occur some time after the postulated accident. Accident risk is estimated by summing the product of estimated dose and the associated probability of occurrence for each of the accident-severity categories analyzed by the RADTRAN computer code.

The cumulative radiation exposure estimated by the NRC staff is provided in Table 3. The corresponding transportation health risks are provided in Table 4. Radiation doses to the population and transport crews were converted to LRFC using the risk coefficient suggested by the National Academy of Sciences (ICRP 1991; NAS 1990). It is important to note that LRFC figures represent cumulative health risks to the entire population exposed to radiation from the shipments. More simply put, the LRFC figures represent the additional number of total potential fatalities assumed within the Clark County population due to the shipment of all of the SNF over the entire life of the transportation campaign to the repository. Table 4 shows that, using the bounding assumptions for this study, between 2 and 3 excess fatal cancers are predicted. The sum of incident-free and accident risks is 2.592 LRFC for the southern route using the beltway; other scenarios have lower estimated risks. More simply put, the LRFC figures represent the additional number of total potential fatalities assumed within the Clark County population due to the shipment of all of the SNF over the entire life of the transportation campaign to the repository. Table 4 shows that, using the bounding assumptions for this study, between 2 and 3 excess fatal cancers are predicted. The sum of incident-free and accident risks is 2.592 LRFC for the southern route using the beltway over the entre life of the transportation campaign to the repository; other scenarios have lower estimated risks.

To put this risk into perspective, the average incidence of lifetime fatal cancer in the U.S. is about 0.25 [25 percent]. Assuming a Clark County population of about 1,600,000 and an average life expectancy of 70 years, this lifetime incidence of fatal cancer would correspond to about 5,700 LRFC/year. Also, in the Clark County area, the average radiation exposures resulting from cosmic and naturally occurring terrestrial gamma radiation are 0.75 to 0.77 mSv/year [75 to 77 mrem/year].⁽⁷⁾ Assuming a Clark County population of about 1,600,000 this natural radiation leads to a risk estimate of about 60 LRFC/year. The average annual excess risk to the Clark County population from SNF transport is less than 0.050 LRFC/year which is a risk estimate of 1,200 times less than the estimate for background radiation and more than 100,000 times less than the average incidence of fatal cancer due to all causes.

The highest estimated risk to the crews is 0.852 LRFC. This already-small risk would be spread over the 40- to 60-year period during which SNF would be transported to the repository. On an annual basis, the crew risk averages about 0.014 LRFC per year of SNF transport as a result of radiation exposures.

The hypothetical maximally exposed individual would for incident-free transport receive 0.40 mSv [40 mrem] for the duration of shipments, about 0.16 percent of the average 70-year dose from background sources.⁽⁸⁾ The maximally exposed individual radiation dose is based on a hypothetical individual member of the public located in the open (i.e., without the shielding offered by buildings or vehicles) 30 m [98 ft] from the highway during the entire duration of shipments (a very conservative assumption). This dose is the estimated risk from incident-free transport.

The above estimates of radiation dose are consistent with the doses reported in 10 CFR Part 51, Table S-4. Table S-4 reports estimates of 0.04 person-Sv [4 person-rem] per reactor year for transportation workers, and 0.03 person-Sv [3 person-rem] per reactor year for the general public. Assuming that 100 nuclear power plants operate for 60 years, Table S-4 leads to estimated occupational and general public doses of 240 person-Sv [24,000 person-rem] and 180 person-Sv [18,000 person-rem] for transportation workers and the general public, respectively. Comparing these dose estimates with the highest corresponding doses in Table 3 shows that the estimated cumulative dose to the general public from incident-free transportation of all SNF through the Las Vegas area is less than 25 percent of the cumulative dose from all fuel and waste transportation calculated from Table S-4. In light of the many conservative assumptions made in this analysis, the NRC staff concludes that the radiological impacts of the shipment of SNF are small and are acceptably addressed using the generic impacts methodology of Table S-4 for individual nuclear power plant operating license renewal purposes.

2.3.2  Nonradiological Risks

The NRC staff assessed the impacts of nonradiological truck accidents that may occur during the transport of SNF to the repository. A nonradiological accident is a truck accident in which the property damage, injuries or fatalities are caused by the force of the impact; no release of or exposure to radiological materials occurs as a result of the truck accident. Data on national accident statistics have been compiled from a number of sources by the U.S. Department of Transportation (DOT), Bureau of Transportation Statistics, between 1975 and 1995. Since 1990, data have been collected on the number of accidents, injuries, and fatalities per 100 million truck-miles (DOT 1999). Based upon the accident rate data from 1990 to 1995, the average rate of large truck accidents is 145 per 100 million truck-km [233 per 100 million truck-miles], the average rate of injury is 13 per 100 million truck-km [21 per 100 million truck-miles], and the average fatality is 0.26 per 100 million truck-km [0.42 per 100 million truck-miles]. On the basis of these statistics--along with the HIGHWAY computer code route data--the expected number of nonradiological accidents, injuries, and fatalities is calculated as shown in Table 5 for shipments during the 40-year (without license renewal) and 60-year (with license renewal) repository operations period. Over a 40- or 60-year period, these risks amount to very small annual risks; less than 0.0015 fatalities per year (with or without license renewal).

The NRC staff also estimated the potential human health effects of vehicle emissions of transport trucks and escort vehicles using conservative assumptions. DOE/EIS-0200-F (page E-32) presents a risk factor for latent mortality from pollution inhalation for truck travel in an urban area; 10 per 100 million truck-km (16 per 100 million truck-miles). DOE reports that no similar estimates are available for rural and suburban areas. However, comparable estimates would be much lower in suburban and rural areas because they are much less densely populated than urban areas . To develop a conservative estimate, the NRC staff assumed that escort vehicles had emissions as large as the large trucks that haul SNF. Further, the NRC staff applied the risk factor to both the urban and suburban areas. The route with the largest distance of combined urban and suburban travel was the south by the beltway route, 59.1 km (36.9 miles) (Table 1). For the license-renewal scenario, an estimate on the order of 75,000 shipments yields total vehicle travel distance of 17.8 million km (11.1 million miles) including both repository-bound and return trips for both the transport truck and the escort vehicle. Using the risk factor reported by DOE yields an expected 1.8 latent mortalities due to pollutant emissions by the transport trucks and escort vehicles for the entire campaign. Assuming a 40-year campaign, this estimate yields an expected 0.045 latent mortalities per year.

To develop a conservative estimate of the potential impact of SNF transport in Clark County, the NRC staff assumed that trucks would make 150,555 trips through the county over the campaign, assuming the license-renewal scenario (approximately 75,000 shipments plus return trips). An equivalent number of trips would be made by an escort vehicle. Using the longest route (Table 1), the one-way distance traveled would be 230.1 km (143 miles) per vehicle. Assuming all SNF transport occurs over a 40-year period, SNF transport in Clark County would involve 0.86 million vehicle km (0.54 million vehicle miles) for the trucks and the same number of vehicle kilometers for escort vehicles. The Nevada Department of Transportation (NDOT)⁽⁹⁾ reports that in 1997 it maintained 839 miles of the 4559 miles of improved road in Clark County, and that NDOT-maintained, Clark-County roads carried 8,611 million vehicle-km (5,382 million vehicle-miles) of travel, about 56 percent of the total vehicle miles of travel in the county. Assuming that SNF shipments occur only on the NDOT-maintained roads and that highway travel does not increase before SNF shipments begin, commercial SNF transport (including both the trucks and the escort vehicles) would account for only about 0.02 percent of the vehicle miles traveled each year on NDOT-maintained roads in Clark County and slightly more than 0.01 percent of the total vehicle miles traveled in the county in a year.

The use of public roads by trucks transporting spent fuel will be required to comply with State of Nevada and local laws regulating vehicle weight and operation. All trucks are subject to registration fees and fuel taxes that have been designed to cover the costs of maintaining and repairing public roads. The use of roads for transporting spent fuel could result in additional road repair and maintenance costs, but such use would also generate additional revenues. Truck registration fees increase according to vehicle weight. The tax on diesel fuel is also designed to recover the costs of maintaining public highways. Because state laws regulate and tax trucks operating in the state, the NRC staff believes that trucks transporting SNF will not cause damage and repair costs that are incommensurate with the taxes and fees the operators must pay.

2.4 Cumulative Impacts of Additional Radioactive Waste Shipments

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In addition to SNF shipments to the proposed repository at Yucca Mountain, DOE is planning to ship quantities of high level waste (HLW) to the repository and may also ship substantial quantities of low-level radioactive wastes (LLW) to the Nevada Test Site (NTS) for disposal. These shipments would most likely be routed through Clark County, in a manner similar to the routing of SNF analyzed above. To estimate the potential cumulative effects of shipments to the NTS as well as the proposed repository, the NRC staff utilized information published in DOE's waste management programmatic EIS (DOE/EIS-0200-F) and DOE's programmatic spent nuclear fuel management EIS (DOE/EIS-0203-F). To assure that cumulative impacts are not underestimated, the NRC staff selected those alternatives in the EIS that led to the highest numbers of shipments to the NTS or Yucca Mountain.

DOE estimated that there would be up to 24,000 HLW shipments⁽¹⁰⁾ to Yucca Mountain and up to 268,000 LLW shipments⁽¹¹⁾ to NTS, and up to 6,815 SNF shipments to NTS.⁽¹²⁾ DOE assumed that the HLW shipments would have radiation doses equal to the legal limit (10 mrem/h at 2 m) and that LLW would have dose rates of 1 mrem/h at 1 m. To estimate the radiological effects of these shipments, the NRC staff assumed that each DOE SNF, HLW or LLW shipment was equal to a shipment of commercial SNF. For the radiological impacts of LLW, the assumption is very conservative because, as indicated by DOE's estimate of 1 mrem/hour (0.01 mSv/hour) at 1 m, LLW is generally much less radioactive than SNF. For non-radiological effects, the NRC staff assumed that each shipment would have the same effect regardless of what material was being transported.

Using highest doses and cancer risks in Tables 3 and 4 and the assumptions above, the NRC staff estimated the doses and LRFCs for shipment of DOE radioactive waste through Clark County. As shown by Tables 6 and 7, the cumulative doses and expected cancer fatalities continue to be small compared to the risk of cancer from other causes.

The non-radiological cumulative effects of radioactive waste shipment through Clark County are dominated by the very large number of LLW shipments. All SNF and DOE radioactive waste and SNF shipments through Clark County would total to more than 374,000 shipments, almost 5 times as many as SNF shipments with license renewal. Thus, between 125 and 250 non-radiological truck accidents can be expected during the 374,000 shipments of radioactive wastes through Clark County. The expected number of accident fatalities is between 0.22 and 0.46 for all shipments of radiological waste over all the years the shipments would occur. Assuming these shipments occurred over a 40-year period, between 3 and 6 traffic accidents involving trucks transporting all types of radioactive waste materials would be expected in an average year, and there would be a very small chance that a fatality would result in any one year.

2.5 Summary of SNF Transport Impacts

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As shown in Table 4, the conservatively estimated LRFC assumed to result from radiation exposure related to transportation of SNF in Clark County over the entire 40-60 year life of the transportation campaign to the repository is between 1.6 and 2.6 (including the risk due to potential accidents) or less than 0.05 LRFC/year. For comparison, it is estimated that there would be about 5700 LRFC for each year in Clark County from causes unrelated to SNF transport.

Non-radiological truck-vehicle accidents are possible as a result of transporting SNF through Clark County. The probability of a fatality is estimated to be less than 0.090 under all scenarios. For license renewal, the combined radiological and non-radiological risk to the general public is estimated to be between about 2.3 and 2.6 fatalities over the entire course of SNF transport through Clark County, including incident-free and accident risks. Without license renewal, the estimated is between about 1.5 and 1.8 fatalities.

The above analysis shows that, even with conservative assumptions, the cumulative radiological and accident risks of SNF transport in Clark County are small. It also shows that alternative assumptions are bounded by this analysis and would result in even smaller human health impacts. Transporting SNF by rail rather than by truck would reduce human health effects by reducing the number of shipments and the likelihood of accidents. Shipping SNF via the proposed beltway would reduce health impacts compared to shipping via the current interstate highway system. In addition, shipping SNF via the proposed beltway would reduce health impacts compared to shipping via the current interstate highway system. The implementation of such mitigative measures must await future decisions that fall well outside of the scope of this rulemaking. DOE will address transportation impacts, mitigation measures, and alternative transportation modes in its EIS for the proposed repository at Yucca Mountain.

2.6 Environmental Justice

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Environmental justice refers to a Federal policy in which Federal actions should not result in disproportionately high and adverse environmental impacts on low-income or minority populations. Executive Order 12898 (59 FR 7629) directs Federal executive agencies to consider environmental justice under NEPA. Although the Executive Order does not apply to the NRC, an independent agency, the NRC has stated that it will comply with the Executive Order.

As explained earlier, only people within 0.8 km [0.5 mile] of the route followed by the trucks transporting SNF would receive any appreciable radiation dose, even under accident scenarios. Consequently, the NRC staff examined available data on low-income and minority populations within that distance along transportation routes to determine if there was reason to suspect that SNF transport impacts might fall disproportionately on low-income or minority groups. To this end, the NRC staff examined the racial, ethnic and population characteristics of Clark County as a whole and the same characteristics of the transportation routes.

Table 8 describes the overall racial and ethnic characteristics for the population groups in Clark County (Bureau of the Census 1990).⁽¹³⁾

Nevada is one of the fastest growing states in the U.S., with Clark County growing faster than any other Nevada county. The 1990 census listed 741,459 people as living in the county (Census Bureau Database C90STF1A; http://venus.census.gov/cdrom/lookup/929978369, accessed June 21, 1999). Clark county's projected 1999 population was 1,337,400, and the projected 2004 population is 1,656,840 (Nevada State Demographer June 1, 1998). Las Vegas accounted for most of the County's growth. In July 1998, an estimated 448,244 persons resided in Las Vegas, a 6 percent increase since July 1997. In addition to residents, Las Vegas has many visitors staying in hotels.

Table 9 reports the percentage of ethnic and racial groups living within 0.5 mile (0.8 km) of the transportation routes. These data were assembled using an Oak Ridge National Laboratory computer program that integrates Map-Info™ with the Census Bureau data available on CD-ROM (U.S. Census Database C90STF1A, 1990). 1990 data were used to be consistent with the population density estimates used in the HIGHWAY computer code. Table 9 shows that only for the route from the northeast through downtown would the fraction of a minority within the 0.8-km (0.5-mile) corridor adjacent to the route be significantly higher than the county average.

The NRC staff also examined the distribution of low-income populations. The 1995 median family income for Nevada families was estimated to be $36,300; Clark County was slightly above the State average with a median family income of $38,184 (U.S. Census Bureau, Table C95-32; accessed June 23, 1999). The estimated number of persons living below the poverty level for 1989 in Clark County was 76,737, representing approximately 10.4 percent of the total population (the figures are based on 1990 Census data). Compared to the U.S. average, the State of Nevada has been substantially below the national average in percentages of people living in poverty. For 1995 through 1997, 13.6 percent of the U.S. population lived in poverty, while 10.1 percent of the residents in Nevada lived in poverty (Bureau of the Census 1999). Accurately examining income distribution is difficult because the poverty data are aggregated over larger areas than are data for ethnic and racial groups. On the basis of 1990 census data, the NRC staff estimated the percent of the populations in poverty along the routes as shown in Table 10. The only route that would encounter higher than the U.S. average of low-income persons is the route from the northeast through downtown.

The analysis suggests that the routes through downtown may run through areas containing a higher proportion of low-income and minority groups than the beltway routes. However, as discussed in Sections 2.3 and 2.4, the radiological and nonradiological impacts of transportation of SNF are small. In addition, these small impacts are dispersed throughout the entire routes and do not appear to fall disproportionately in any one area. Based on the above analysis the NRC staff concludes the overall impacts of transportation of SNF will not likely be disproportionately high or adverse for any minority or low-income population.

1. This exception only applies to the two entries in Table B-1 labeled "Offsite radiological impacts (collective effects)" and "Offsite radiological impacts (spent fuel and high level waste disposal).

2. Any generic conclusions by the Commission concerning the cumulative impacts of transportation associated with nuclear power plant license renewal would in no way affect any U.S. Department of Energy (DOE) decision concerning the suitability of Yucca Mountain, any consideration that DOE may give to transportation impacts in making that decision, and is not intended to support any other regulatory decision by the NRC.

3. DOE's Notice of Intent indicates that its analyses of impacts of regional transportation issues will include (a) technical feasibility, (b) socioeconomic impacts, (c) land use and access impacts, and (d) impacts of constructing and operating a rail spur, a heavy haul route, and/or a transfer facility. 60 FR 40168.

4. After DOE's publication of the final EIS for Yucca Mountain, the Commission will consider whether the information contained therein would be considered new and significant in the context of decisions related to the renewal of nuclear power plant operating licenses such that some additional action may be required.

5. The NRC staff did not consider conservative analyses that would be outside the reasonable range of assumptions, e.g., routing shipments on indirect routes through densely populated areas. While the NRC staff did make many conservative assumptions, consistent with U.S. Department of Transportation regulations for highway route controlled quantities of nuclear materials (49 CFR 397.101), the NRC staff assumed that the trucks would be routed on interstate highways to the maximum possible extent.

6. Although these estimates exceed the 70,000 MTHM limit for the first repository in the NWPA, they represent conservative assumptions (i.e., overestimates) that would define an upper bound of potential impacts for a repository at Yucca Mountain.

7. This outdoor dose rate estimate was provided by H. L. Beck (H. L. Beck, Director, Environmental Sciences Division, Environmental Measurements Laboratory, U.S. Department of Energy, New York, personal communication via electronic mail to A. K. Roecklein, NRC, Rockville, Maryland., Nov. 4, 1998) and based on extensive background radiation measurements summarized, in part, in NCRP Report No. 94, Exposure of the Population in the United States and Canada from Natural Background Radiation, National Council on Radiation Protection and Measurements, Bethesda, Maryland., Dec. 30, 1987.

8. The background radiation dose is assumed to be 3.6 mSv/year [360 mrem/year], the current estimate given for average background radiation dose in the U.S. The value is based upon the following assumptions from the National Council on Radiation Protection and Measurements as summarized in Eisenbud and Gesell (1997). Doses are given in mSv/year:

Cosmic radiation that reaches the earth at sea level 0.27
Radiation from the natural elements in the earth 0.28
Radon gas in the home from ground sources 2.00
Radiation in the human body from food and water 0.39
Average medical exposure 0.25 to 0.55
Consumer products (e.g., smoke detectors) 0.10

9. State of Nevada Transportation Facts and Figures. Operations Analysis Division, Nevada Department of Transportation, January 1999. Accessed at http://www.nevadadot.com/about/fact/, July 23, 1999.

10. This estimate comes from DOE/EIS-0200-F; Table 9.16-1, Centralized Alternative.

11. This estimate is composed of 257,000 truck shipments of LLW to the Nevada Test Site and 11,000 shipments of low-level mixed waste (DOE/EIS-0200-F; Table 7.16-2, Centralized-2 Alternative and Table 6.16-2, Regionalized-3 Alternative).

12. This estimate comes from DOE/EIS-0203-F, Table I-2, for the Centralization at NTS alternative.

13. Per Office of Management and Budget 1998 Directive No. 15, the Census Bureau uses four race categories (White, Black, American Indian and Alaska native, Asian and Pacific Islander) and two ethnicity categories, Hispanic and non-Hispanic (Bureau of the Census 1998).