10 CFR Part 51, Environmental Protection Regulations for Domestic Licensing and Related Regulatory

PNNL-31722

Recommendations for an
Applicant to Calculate
Activity Data for
Greenhouse Gases
Estimates
September 2024
Saikat Ghosh

Prepared for the U.S. Nuclear Regulatory Commission
Office of Nuclear Regulatory Research
Under Contract DE-AC05-76RL01830
Interagency Agreement: 31310019N0001
Task Order Number: 3131002F0009

Choose an item.

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PNNL-31722

Recommendations for an Applicant to
Calculate Activity Data for Greenhouse Gases
Estimates

September 2024

Saikat Ghosh

Prepared for the U.S. Nuclear Regulatory Commission
Office of Nuclear Regulatory Research
Under Contract DE-AC05-76RL01830
Interagency Agreement: 31310019N0001

Pacific Northwest National Laboratory
Richland, Washington 99354

PNNL-31722

Acronyms and Abbreviations
CFR

Code of Federal Regulations

CO

carbon monoxide

CO2

carbon dioxide

CO2(e)

CO2 equivalent

EF

emission factor

EPA

Environmental Protection Agency

g/hp-hr

gram(s) per horsepower-hour

GHG

greenhouse gas

g/T-mi

gram(s) of pollutant per ton-mile

hp

horsepower(s)

hp-hr

horsepower-hour(s), unit of energy

kW

kilowatt(s)

kWh

kilowatt-hour(s)

lb/MWh

pound(s) per megawatt-hour

LWR

light-water reactor

mi

miles

MT

metric ton(s)

MW

megawatt(s)

MWe

megawatt(s) electrical

MWh

megawatt-hour(s), unit of energy

N

number of engines

NRC

U.S. Nuclear Regulatory Commission

NR GEIS

Generic Environmental Impact Statement for Licensing of New Nuclear
Reactors

PPE

plant parameter envelope

SAFSTOR

safe storage

scf

standard cubic foot/feet

SWU

separative work unit

UniStar

UniStar Nuclear Services, LLC

VMT

vehicle mile(s) traveled

Acronyms and Abbreviations

ii

PNNL-31722

Contents
Acronyms and Abbreviations ........................................................................................................ ii
Contents........................................................................................................................................iii
1.0

Introduction ....................................................................................................................... 2

2.0

Activity Data Plant Parameter Envelope ........................................................................... 5

3.0

Methodology ...................................................................................................................... 6
3.1

Uranium Fuel Cycle ............................................................................................... 6

3.2

Construction .......................................................................................................... 7

3.3

Equipment............................................................................................... 7

3.2.2

Vehicular Traffic from Workforce ............................................................ 8

Plant Operations .................................................................................................... 9
3.3.1

Diesel Fired Generators.......................................................................... 9

3.3.2

Vehicular Traffic from Workforce ............................................................ 9

3.4

Fuel and Waste Transportation ............................................................................. 9

3.5

Decommissioning ................................................................................................ 10

3.6
4.0

3.2.1

3.5.1

Equipment............................................................................................. 10

3.5.2

Vehicular Traffic from Workforce .......................................................... 10

SAFSTOR Workforce Vehicular Traffic ............................................................... 10

References ...................................................................................................................... 11

Figures
Figure 1.

Percentage Distribution of Total Green House Gas Emissions for Two
1000 MWe Nuclear Reactors. ............................................................................... 4

Tables
Table 1.

Plant Parameter Envelope Values for Green House Gas Emissions as
Provided in Generic Environmental Impact Statement for Licensing of
New Nuclear Reactors .......................................................................................... 3

Table 2.

Upper Bounding Activity Data Based on Two 1000 MWe Nuclear
Reactors for an Applicant to Demonstrate Its Total Lifecycle Green House
Gas Emissions Equal to or Below 2534,000 MT CO2(e) ....................................... 5

Contents

iii

PNNL-31722
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1

PNNL-31722

1.0 Introduction
In 2009, the U.S. Nuclear Regulatory Commission (NRC) directed the NRC staff to address
climate change issues and consider the impacts of the emissions of carbon dioxide (CO2) and
other greenhouse gases (GHGs) in its environmental reviews for major licensing actions (NRC
2009b). To implement this direction from the Commission, the staff issued guidance in 2011 and
updated guidance in 2014 in Attachment 1 to Interim Staff Guidance COL/ESP-ISG-026 (NRC
2011; NRC 2014). This guidance provides a simpler method than the method described in
RG 4.2 Rev. 3, that an applicant can use to meet the plant parameter envelope (PPE) value
from the Generic Environmental Impact Statement for Licensing of New Nuclear Reactors
(NR GEIS). NRC staff estimated the 97-year lifecycle GHG emissions from a reference
1000 megawatt electrical (MWe) light-water reactor (LWR) for various activities associated with
construction, operation (including uranium fuel cycle), and decommissioning of nuclear power
plants and presented the results in Appendix H of the NR GEIS. Appendix H of the NR GEIS
includes estimates of direct emissions from construction equipment and emergency diesel
engines in a nuclear facility and indirect emissions from workforce vehicular traffic, fuel
transportation and the uranium fuel cycle.
The NR GEIS Section 3.3 extended the estimates in Appendix H for the installation of two
1000 MWe nuclear reactors on the same site. Scaling factors were used to extrapolate the GHG
emissions of a reference 1000 MWe reactor to a two-unit nuclear reactor plant (each reactor
unit generating 1000 MWe). GHG emission estimates for building, operation, decommissioning
and safe storage (SAFSTOR)1 for a two-unit nuclear reactor plant would be based on the plant’s
physical size, and therefore estimates for these source categories were assumed to be twice
the value of the reference 1000 MWe reactor. However, GHG emissions from the fuel cycle
(including fuel transportation) were scaled upward by a factor of 3, based on plant efficiencies
greater than the 80 percent assumption in Appendix H. Table 1 below shows the PPE emissions
for two 1000 MWe nuclear reactors as provided in NR GEIS. The total GHG emissions for two
1000 MWe reactors were calculated as 2,534,000 metric tons (MT) of CO2 equivalent (CO2(e))
based on a 97 year GHG life cycle period. The GHG emissions lifetime of 97 years for a
reference nuclear reactor includes a 7-year building phase, 40 years of operation, 10 years of
active decommissioning, and 40 years of SAFSTOR operations (NRC 2024). Construction
equipment and vehicular traffic from workers commute would contribute to the GHG emissions
during a 7-year building phase. Uranium fuel cycle, vehicular traffic, fuel and waste
transportation, and testing of standby diesel generators would contribute to GHG emissions
during the 40-year operations phase. While NRC’s regulations allow up to 60 years of reactor
facility decommissioning, Appendix H estimated that most of the GHGs would occur over an
estimated 10-year period during which to the licensee would engage in significant demolition
and earth-moving activities, as discussed in Supplement 1 to NUREG-0586 (NRC 2002).
Vehicular traffic by the workforce during a 40-year SAFSTOR period would additionally
contribute GHG emissions. The carbon footprint for a 40-year SAFSTOR period was separately
analyzed from the decommissioning activities as provided in Table YYYY-2 of the staff issued
guidance in 2011 (NRC 2011).

A type of decommissioning in which the facility is placed in a safe, stable condition and maintained in
that state (safe storage) until it is subsequently decontaminated and dismantled to levels that permit
license termination. Radioactive decay occurs during the SAFSTOR period, thus reducing the quantity of
contaminated and radioactive material (NRC 2002).

1

Introduction

2

PNNL-31722
Table 1.

Plant Parameter Envelope Values for Green House Gas Emissions as Provided
in Generic Environmental Impact Statement for Licensing of New Nuclear
Reactors
Based on
1000 MWe
Reactor

Life Cycle Phase
Construction
Plant Operations
Uranium Fuel Cycle
Fuel and Waste Transportation
Decommissioning
SAFSTOR
Total

Process
categories
Equipment
Workforce Traffic
Diesel engines
Workforce Traffic
Fuel Enrichment
Truck Traffic
Equipment
Workforce Traffic
Workforce Traffic
-

Activity Emissions
Duration
(MT
(years)
CO2(e))
39,000
7
43,000
181,000
40
136,000
40
540,000
40
14,000
19,000
10
8000
40
10,000
990,000

Based on
Two
1000 MWe
nuclear
reactors

Based on
Two
1000 MWe
nuclear
reactors

Scaling
Factor
2
2
2
2
3
3
2
2
2
-

Emissions
(MT CO2(e))
78,000
86,000
362,000
272,000
1,620,000
42,000
38,000
16,000
20,000
2,534,000

CO2(e) = CO2 equivalent; MT = metric ton(s); MWe = megawatt(s) electrical; SAFSTOR = safe storage.

Figure 1 provides a visualization of the GHG emissions breakdown by different categories for
two 1000 MWe nuclear reactors. The bulk of the emissions are contributed by the uranium fuel
cycle and plant operations. Therefore, it is recommended that an applicant provide the best
available data for these two source categories to demonstrate the GHG emissions from the
proposed site.
An applicant is required to demonstrate that the total 97-year GHG lifecycle emissions from the
new reactor would be equal to or less than the PPE value from the NR GEIS for a 1,000 MWe
LWR of 2,534,000 MT CO2(e). Regulatory Guide 4.2, “Preparation of Environmental Reports for
Nuclear Power Stations,” Revision 3 (RG 4.2) provides the methods that an applicant can use to
estimate its GHG emissions for various activities. The NR GEIS relied upon a method described
in the RG 4.2 Revision 3 and in Interim Staff Guidance COL/ESP-ISG-026, “Environmental
Issues Associated with New Reactors” (NRC 2018, NRC 2014). As an alternative to the method
in RG 4.2 Revision 3, a simpler method is provided in this document that an applicant can use
to meet the PPE value from the NR GEIS without the need for a detailed GHG emissions
estimation.
This document provides an approximate account of the activity data that were used for the
generation of the GHG estimates in Appendix H of the NR GEIS. The activity data were
retrieved for a 1000 MWe reference reactor from data sources in Appendix H and then
extrapolated for two 1000 MWe nuclear reactors using the same scaling factors for the relevant
source categories. An applicant can determine if its proposed activity for relevant source
categories in Table 1 is equal to or lower than the corresponding activity data for two 1000 MWe
nuclear reactors as provided in Section 2.0 of this report.

Introduction

3

PNNL-31722

Figure 1.

Introduction

Percentage Distribution of Total Green House Gas Emissions for Two 1000 MWe
Nuclear Reactors.

4

PNNL-31722

2.0 Activity Data Plant Parameter Envelope
Table 2 summarizes the activity data based on GHG emissions from construction, operation,
and decommissioning two 1000 MWe reactors. An applicant can use these values as upper
bounding PPE values to meet the PPE emissions target of 2,534,000 MT of CO2(e) in Table 1.
Table 2. Upper Bounding Activity Data Based on Two 1000 MWe Nuclear Reactors for an
Applicant to Demonstrate Its Total Lifecycle Green House Gas Emissions Equal to or
Below 2534,000 MT CO2(e)
Process
Life cycle phase
categories
Construction
Equipment
Workforce Traffic
Plant Operations
Generators
Workforce Traffic
Uranium Fuel
Ore milling and fuel
Cycle
enrichment
Fuel and Waste
Truck Shipments
Transportation
Decommissioning
SAFSTOR

Equipment
Workforce Traffic
Workforce Traffic

Activity
PPE
281,800
2,000
560,000
1,100
25
350
700,000
140,000
400
80

Activity Unit Based on Two 1000 MWe
Nuclear Reactors
MWh total energy output
Onsite staff driving 40 mi per day
MWh total energy output
Onsite staff driving 40 mi per day
Million SWUs
Truck shipments per year with one-way distance
of 1000 mi
VMT per year (round trip)
MWh total energy output
Onsite staff driving 40 mi per day
Onsite staff driving 40 mi per day

MWe = megawatt(s) electrical; mi = mile(s); MWh = megawatt(s)-hour; PPE = plant parameter envelope;
SAFSTOR = safe storage; SWU = separative work unit; VMT = vehicle mile(s) traveled.

Activity Data Plant Parameter Envelope

5

PNNL-31722

3.0 Methodology
3.1 Uranium Fuel Cycle
The uranium fuel cycle starts with uranium ore mining and uranium milling. In the United States,
most uranium is extracted through the in-situ recovery process, where uranium is removed from
the underground deposits, brought to the surface, and then further processed. The uranium is
eventually processed into yellowcake (U3O8) (NRC 2009a). Thereafter, the yellowcake is
converted to UF6 and enriched (e.g., increase the isotopic concentration of U-235 to 5 percent)
in an enrichment plant using a gas centrifuge process. It is further converted into nuclear fuel in
a fabrication facility by mechanically and chemically converting the UF6 gas to UO2 powder. The
powder is further processed into fuel rods and transported to a reactor. After use in the nuclear
reactor, the spent fuel is put into long-term storage, typically by first being placed into a spent
fuel pool for several years until, after several years of cooling, the spent fuel can be loaded into
passively cooled NRC-certified “dry” storage casks and appropriately placed within an
independent spent fuel storage facility.
The NRC’s Table S-3, which is codified in Title 10 Code of Federal Regulations (CFR)
Section 51.51(b) assumes that approximately 135,000,000 standard cubic feet (scf) of natural
gas is required per year to generate process heat for certain portions of the uranium fuel cycle.
Natural gas is burned to supply process and building heat during various stages of the uranium
fuel cycle including milling, UF6 conversion, and fuel fabrication facilities (AEC 1974, NRC
1976). Significant amounts of CO2 can be emitted from such natural gas combustion in the
uranium fuel cycle. Table S-3 assumptions are based on a 1000 MWe LWR nuclear power plant
operating at 80 percent capacity. The reference 1000 MWe LWR would require about 5 million
separative work units (SWUs)2 to generate fresh fuel (3.2 percent U-235) from about 11,640 MT
natural uranium over the lifetime of 40 years (AEC 1974). Appendix H calculated 7440 MT
CO2(e) emissions per year based on natural gas consumption data from Table S-3 and a
conversion factor of 0.551 MT CO2 per thousand scf of natural gas combustion. For a 40-year
operational life of a 1000 MWe LWR, this is 298,000 MT of CO2(e).
Additionally, a large amount of electrical energy is consumed by the centrifuge plants to enrich
the raw uranium fuel. Appendix H calculated the amount of enriched fuel and SWUs needed to
enrich the fuel in a centrifuge based on the fuel burnup in a 1000 MWe power plant with
95 percent capacity and 35 percent thermal efficiency. More details about these calculations
and assumptions are provided in Napier (2020). Appendix H shows the total uranium fuel of
1043 MT of 5 percent U-235 required in a 1000 MWe nuclear reactor during the operational
period of 40 years. To produce 1 ton of 5 percent enriched uranium with 0.25 percent U-235 in
the depleted uranium stream requires extraction of 10.3 tons of natural uranium and
7,923 SWUs. Thus, 1043 MT of enriched uranium would require about 8.26 million SWUs and
10,743 MT of natural uranium. Because a centrifuge enrichment facility requires about
50 kilowatt hours (kWh) per SWU, a total of 413,200 megawatt-hour (MWh) is needed to
produce 40 years’ worth of uranium enriched to 5 percent U-235 for fuel for the lifetime
operation of the plant. For the existing centrifuge enrichment plant in the United States, the
regional average CO2 emission factor is 1,248 pound(s) per megawatt-hour (lb/MWh), and the
total CO2 emission is about 243,000 MT. The CO2 emissions from the centrifuge facility may
increase up to 824,000 MT for generating 20% enriched uranium for a 1000 MWe reactor.
2

SWU is the amount of energy required in the enrichment process to separate the U-235 and U-238 in
the feed assay.

Methodology

6

PNNL-31722
Thus, Appendix H of the NR GEIS calculates the total GHG emissions as 540,000 MT CO2(e)
from electricity consumption by a gas centrifuge for fuel enrichment and natural gas combustion
for generating process heat. These uranium fuel cycle GHG emissions from a reference
1000 MWe reactor can be extrapolated to 1,620,000 MT CO2(e) for two 1000 MWe reactors
using a scaling factor of 3. The scaling factor is based on plant efficiencies greater than the
80 percent assumption for the LWR in Appendix H of the NR GEIS. It is to be noted though that
the enrichment process (indirect emissions from electricity consumption) already accounted for
95 percent efficiency. Nevertheless, a scaling factor of 3 would provide a conservative bounding
value for GHG emissions from the uranium fuel cycle.
Based on the above assumptions, two 1000 MWe nuclear reactors would require 3129 MT of
enriched uranium fuel over the lifetime of 40 years based on a scaling factor of 3. About
24.8 million SWUs would be required to generate 3129 MT of 5 percent enriched uranium.
Thus, the expected SWUs for an applicant’s project should be equal to or less than 24.8 million
SWUs to meet the GHG target in the NR GEIS. This target quantity of SWUs is a conservative
estimate for both indirect centrifuge plant emissions and natural gas combustion for process
heat. The natural gas combustion-related CO2 emissions are based on a 1000 MWe LWR in
Table S-3 that had a lower number of SWUs.
An applicant can calculate the SWU requirements based on its proposed fuel burnup, capacity,
and annual fuel requirement (amount of enriched uranium fuel) as shown above. An applicant
can determine its SWUs and natural uranium requirements using an SWU calculator (e.g.,
https://www.uxc.com/p/tools/FuelCalculator.aspx ).

3.2 Construction
GHGs (primarily CO2) can be directly emitted from various diesel engines operated for
construction activities such as dewatering and earthwork, batch plant, concrete, rigging, shop
fabrication, warehouse, and equipment maintenance. Indirect GHG emissions can be attributed
to vehicular traffic due to the onsite workforce. These two source categories have a different set
of methods to calculate GHG emissions as outlined in Appendix H of the NR GEIS.

3.2.1

Equipment

Construction activities typically generate GHG emissions from the use of off-road vehicles that
are fueled with diesel or gasoline. Appendix H of the NR GEIS calculated the GHG emissions
from various construction activities based on carbon monoxide (CO) emissions provided by
UniStar Nuclear Services, LLC (UniStar) in their application for a 1000 MWe power plant
(UniStar 2007). The CO emissions from all these activities were converted to CO2 emissions
with a scaling factor of 172 tons of CO2 per ton of CO. UniStar compiled emission factors from
various data sources including the U.S. Environmental Protection Agency’s (EPA’s) NONROAD
model. The emission factors for nonroad compression engines are generally based on the rated
horsepower (hp) and the model year. Depending on the model year, EPA provides emission
factors under five regulations that establish up to four tiers of federal nonroad emission
standards3 (EPA 2018). UniStar compiled a detailed level of activity data for various off-road
diesel engines during the proposed 7 years of construction.

3

40 CFR Part 89 provides Tier 1, 2, and 3 exhaust emission standards and 40 CFR Part 1039 provides
Tier 4 emission standards.

Methodology

7

PNNL-31722
Appendix H calculated the total GHG emissions (primarily CO2) as 39,000 MT of CO2(e) during
7 years of construction of a 1000 MWe power plant. This was scaled to 78,000 MT CO2(e) for
the construction of two 1000 MWe reactors based on a scaling factor of 2.
A simplified activity data of 281,800 MWh was back-calculated using CO2 emission factor (EF)
(=172*1.2 gram per horsepower-hour [g/hp-hr]) for a 175-300 hp compression engine that would
generate 78,000 MT CO2(e) emissions. An applicant can compute the total energy output based
on the number of engines (N) used in construction and combined yearly hours of use as shown
below:
𝑇𝑜𝑡𝑎𝑙 𝐸𝑛𝑒𝑟𝑔𝑦 𝑀𝑊ℎ =

𝐻𝑜𝑟𝑠𝑒𝑝𝑜𝑤𝑒𝑟 ℎ𝑝 × 𝑇𝑜𝑡𝑎𝑙 𝑁𝑜. 𝑜𝑓 ℎ𝑜𝑢𝑟𝑠 𝑜𝑓 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑜𝑛 ℎ
ℎ𝑝
1341
𝑀𝑊

1

The total number of operating hours is equal to the product of hours per year and duration of
activity in years. The total energy consumption (MWh) is equivalent to the sum of energy
consumption for all N engines at a site.
These calculations assume the EF for 150-300 hp diesel engines. If an applicant has gasoline
engines, this value would be still conservative since EF for gasoline engines are much lower
than those for diesel engines. Similarly, diesel engines with higher power capacity (>300 hp)
would also have lower emissions. More activity of lower capacity engines (Tier 1) would have
higher emissions. An applicant should describe assumptions used while demonstrating their
activity data to meet the GHG PPE values in Table 2.
For example, the same amount of GHG emissions (78,000 MT) would be generated by using
200 diesel engines with 300 hp, each operating for 900 hours per year over the construction
period of 7 years.

3.2.2

Vehicular Traffic from Workforce

Vehicular traffic emissions occur during the commute of the workforce to and from onsite
construction sites. The total GHG emissions in Appendix H of the NR GEIS were computed as
43,000 MT of CO2(e) by combining the number of round trips (=1000), average commute
distance, days per year of commute, duration of construction, vehicle fuel efficiency, and CO2
emissions (MT) per gallon. This method assumed 365 days per year of commuting, the fuel
efficiency of 21.6 mpg, and the CO2 EF of 0.0089 MT per gallon of fuel. More detailed
calculations and assumptions are provided in Chapman et al. (2012).
Vehicle miles traveled (VMT) is a general traffic indicator that can also be used as a bounding
value for such estimates. It can be calculated as follows:
𝑉𝑀𝑇 𝑝𝑒𝑟 𝑑𝑎𝑦 =

𝑇𝑟𝑖𝑝𝑠 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑚𝑖𝑙𝑒𝑠
×
𝑑𝑎𝑦
𝑡𝑟𝑖𝑝

2

CO2 emissions were then calculated from the VMT estimate:
𝐶𝑂 𝐸𝑚𝑖𝑠𝑠𝑖𝑜𝑛𝑠 =
×

Methodology

3

× 𝑑𝑢𝑟𝑎𝑡𝑖𝑜𝑛 𝑦𝑒𝑎𝑟𝑠 × 𝑣𝑒ℎ𝑖𝑐𝑙𝑒 𝑓𝑢𝑒𝑙 𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦

×

8

PNNL-31722
The number of trips per day can be assumed to be equal to the number of onsite staff assuming
that each workforce staff drives one car to work (no carpooling). Thus, 2000 onsite staff driving
for 40 miles (mi) per day over 7 years would generate the same amount of GHG emissions for
construction activity of two nuclear reactors, i.e., 86,000 MT of CO2(e). Thus, a volume of
80,000 VMT per day over the period of 7 years would also generate the same GHG emissions.

3.3 Plant Operations
Similar to construction activities, CO2 can be directly emitted from operations of standby and
emergency diesel generators and indirectly emitted from vehicular traffic.

3.3.1

Diesel Fired Generators

Appendix H of the NR GEIS shows the CO2 emission calculations based on CO emissions from
four emergency generators (10130 kilowatts [kW]) operated for a total of 600 hours per year and
two station blackout generators (5000 kW) operated for 200 hours per year as provided in the
UniStar application (UniStar 2007). The total emissions were calculated as 181,000 MT of
CO2(e) for a 1000 MWe power plant using a conversion factor of 172 tons of CO2 per ton of CO
emissions. This value was scaled to 362,000 MT of CO2(e) for two 1000 MWe nuclear reactors.
The combined activity was 280,000 MWh energy output during 40 years of operations of the
emergency generators for a 1000 megawatts (MWs) reactor. This output can be scaled to
560,000 MWh energy output for two 1000 MW nuclear reactors. For example, five diesel
generators with 10,000 kW heat input operating for 40 years with 280 hours per year would
generate the same emissions of 362,000 MT of CO2(e). An applicant may calculate the total
activity of N diesel generators for operations using Equation 3 above.

3.3.2

Vehicular Traffic from Workforce

Vehicular traffic emissions for operations were computed in Appendix H of the NR GEIS in a
manner similar to construction activities. A workforce of 550 onsite staff was used to compute
the total emissions during 40 years of operations with the same fuel efficiency and CO2 EF.
Thus, this value can be scaled to 1100 onsite workforce staff driving 40 mi per day over
40 years for two 1000 MW nuclear reactors. A volume of 44,000 VMT per day over 40 years
would also generate the same GHG emissions of 272,000 MT CO2(e).

3.4 Fuel and Waste Transportation
Appendix H of the NR GEIS computed CO2 emissions from fuel and waste transport by truck
and rail shipments to and from a LWR using survey data in Table S-5 of Supplement 1 to
WASH-1238 (AEC 1972). The CO2 emissions were calculated using a CO2 EF of 64.7 grams of
pollutant per ton-mile (g/T-mi) for trucks and 32.2 g/T-mi for rail shipments. The transportation
package’s weight was assumed as 23 MT and 100 MT for truck and rail shipments respectively.
These data were based on an 1100 MWe model LWR in WASH-1248. The total VMT per year
equals 155,000 mi of rail shipments and 20,000 mi of rail shipments including the return of
empty packages for fresh and spent fuel (two-way trips). The total emissions for a model
1100 MWe reactor in Appendix H of the NR GEIS was 14000 MT CO2(e) from both truck and
rail shipments using the CO2 EF for trucks and rail. It is assumed that all the radioactive waste
transport is by rail for CO2 emission calculations.

Methodology

9

PNNL-31722
These emissions can be extrapolated to 42,000 MT CO2(e) for two 1000 MWe nuclear reactors
based on the scaling factor of 3. The total VMT can be back-calculated to be 700,000 mi per
year from these emissions for two 1000 MW reactors assuming all the shipments are
transported by trucks. If rail transport is used for shipments, the total VMT should be
significantly less than this target value since emissions are higher from rail shipments.
An applicant may calculate the total VMT for truck shipments for N fuel and waste shipments
using the following equation:
𝑇𝑜𝑡𝑎𝑙 𝑉𝑒ℎ𝑖𝑐𝑙𝑒 𝑀𝑖𝑙𝑒𝑠 𝑇𝑟𝑎𝑣𝑒𝑙𝑙𝑒𝑑 𝑉𝑀𝑇
=

4

𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑆ℎ𝑖𝑝𝑚𝑒𝑛𝑡𝑠 𝑝𝑒𝑟 𝑦𝑒𝑎𝑟 𝑡𝑟𝑢𝑐𝑘 × 𝑇𝑦𝑝𝑖𝑐𝑎𝑙 𝑜𝑛𝑒

− 𝑤𝑎𝑦 𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑚𝑖𝑙𝑒𝑠 × 2 × 𝑁𝑜. 𝑜𝑓 𝑜𝑝𝑒𝑟𝑎𝑡𝑖𝑛𝑔 𝑦𝑒𝑎𝑟𝑠
Alternatively, 350 truck shipments per year with an average one-way distance of 1000 mi would
result in the same emissions of 42,000 MT CO2(e).

3.5 Decommissioning
3.5.1

Equipment

Appendix H of the NR GEIS assumes that the emissions and related activity for
decommissioning would be one-half (a factor of 0.5) of those for construction activities. Thus,
the total energy consumption (MWh) for the decommissioning equipment in Table 2 was
calculated as one-half of that for construction, i.e., 140,000 MWh, resulting in 38,000 MT of
CO2(e) for two 1000 MWe nuclear reactors.
An applicant can make the same assumption that emissions would be one-half those of their
construction activities. If the applicant has more detailed data, then they can use the above
equation 3 to compute the total power consumption (MWh) for all equipment utilizing their
horsepower output and number of operating hours.

3.5.2

Vehicular Traffic from Workforce

Appendix H of the NR GEIS computed CO2 emissions for a 1000 MWe power plant based on
200 round trips per day, 40 mi per trip, 250 days of work in a year, and 10 years of
decommissioning activities. The total VMT is equal to 8000 mi per day for 200 onsite staff. This
could be extrapolated to 16000 mi per day contributed by 400 onsite staff to generate
16,000 MT of CO2(e) for two 1000 MWe nuclear reactors.

3.6 SAFSTOR Workforce Vehicular Traffic
Appendix H of the NR GEIS computed the vehicular traffic emissions of 10,000 MT of CO2(e) for
a 1000 MWe reference reactor based on 40 onsite employees during 40 years of SAFSTOR
activities. This can be extrapolated to 80 onsite staff driving 40 mi per day for 365 days per year
over 40 years for two 1000 MWe nuclear reactors. The total VMT per day would be 3200 mi per
day.

Methodology

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4.0 References
10 CFR Part 51. Code of Federal Regulations, Title 10, Energy, Part 51, “Environmental
Protection Regulations for Domestic Licensing and Related Regulatory Functions.”
40 CFR Part 89. Code of Federal Regulations, Title 40, Protection of Environment, Part 89,
“Control of Emissions from New and In-Use NONROAD Compression-Ignition Engines.”
40 CFR Part 1039. Code of Federal Regulations, Title 40, Protection of Environment, Part 1039,
“Control of Emissions from New and In-Use Nonroad Compression-Ignition Engines.”
AEC (U.S. Atomic Energy Commission). 1972. Environmental Survey of Transportation of
Radioactive Materials to and from Nuclear Power Plants. WASH-1238, Washington, D.C.
Agencywide Documents Access and Management System (ADAMS) Accession No.
ML14092A626.
AEC (U.S. Atomic Energy Commission). 1974. Environmental Survey of the Uranium Fuel
Cycle. WASH–1248, Washington, D.C. ADAMS Accession No. ML14092A628.
Chapman, E.G., J.P. Rishel, J.M. Niemeyer, K.A. Cort, and S.E. Gulley. 2012. Assumptions,
Calculations, and Recommendations Related to a Proposed Guidance Update on Greenhouse
Gases and Climate Change. PNNL-21494, Pacific Northwest National Laboratory, Richland,
Washington. ADAMS Accession No. ML12310A212.
EPA (U.S. Environmental Protection Agency). 2018. Exhaust and Crankcase Emission Factors
for Nonroad Compression-Ignition Engines in MOVES2014b. EPA-420-R-18-009, Office of
Transportation and Air Quality, Washington, D.C.
Napier, B.A. 2020. Non-LWR Fuel Cycle Environmental Data. PNNL-29367, Revision 2,
Richland, Washington. ADAMS Accession No. ML20267A217.
NRC (U.S. Nuclear Regulatory Commission). 1976. Environmental Survey of the Reprocessing
and Waste Management Portions of the LWR Fuel Cycle. NUREG-0116 (Supplement 1 to
WASH-1248).
NRC (U.S. Nuclear Regulatory Commission). 2002. Final Generic Environmental Impact
Statement of Decommissioning of Nuclear Facilities: Regarding the Decommissioning of
Nuclear Power Reactors. NUREG-0586, Supplement 1, Volumes 1 and 2, Washington, D.C.
ADAMS Accession Nos. ML023470327, ML023500228.
NRC (U.S. Nuclear Regulatory Commission). 2009a. Generic Environmental Impact Statement
for In-Situ Leach Uranium Milling Facilities. NUREG-1910, Volumes 1 and 2, Washington, D.C.
ADAMS Accession Nos. ML15093A359, ML15093A480.
NRC (U.S. Nuclear Regulatory Commission). 2009b. “Memorandum and Order in the Matter of
Duke Energy Carolinas, LLC (Combined License Application for William States Lee III Nuclear
Station, Units 1 and 2) and Tennessee Valley Authority (Bellefonte Nuclear Power Plant, Units 3
and 4).” CLI-09-21, Rockville, Maryland. ADAMS Accession No. ML093070690.

References

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NRC (U.S. Nuclear Regulatory Commission). 2011. Staff Memorandum from B Clayton to SC
Flanders, dated March 4, 2011, regarding “Revision 1 - Addressing the Construction and
Preconstruction Activities, Greenhouse Gas Issues, General Conformity Determinations,
Environmental Justice, the Need for Power, Cumulative Impact Analysis and Cultural/Historical
Resources Analysis Issues in Environmental Impact Statements.” Washington, D.C. ADAMS
Accession No. ML110380369.
NRC (U.S. Nuclear Regulatory Commission). 2014. COL/ESP-ISG-026, “Interim Staff Guidance
on Environmental Issues Associated with New Reactors.” Washington, D.C. ADAMS Accession
No. ML13347A915.
NRC (U.S. Nuclear Regulatory Commission). 2018. Preparation of Environmental Reports for
Nuclear Power Stations. Regulatory Guide 4.2, Revision 3, Washington, D.C. ADAMS
Accession No. ML18071A400.
NRC (U.S. Nuclear Regulatory Commission). 2024. Generic Environmental Impact Statement
for Advanced Nuclear Reactors. NUREG-2249, Washington, D.C. ADAMS Accession No.
ML24176A220.
UniStar (UniStar Nuclear Services, LLC). 2007. Technical Report in Support of Application of
UniStar Nuclear Energy, LLC and UniStar Nuclear Operating Services, LLC for Certificate of
Public Convenience and Necessity Before the Maryland Public Service Commission for
Authorization to Construct Unit 3 at Calvert Cliffs Nuclear Power Plant and Associated
Transmission Lines – Public Version. Public Service Commission of Maryland, Baltimore,
Maryland. ADAMS Accession No. ML090680053.

References

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