A Compendium of Spent Fuel 

Transportation Package 

Response Analyses to Severe 

Fire Accident Scenarios 

Final Report

Office of Nuclear Material Safety and Safeguards

NUREG/CR-7209

PNNL-24792

 

A Compendium of Spent Fuel 

Transportation Package 

Response Analyses to Severe 

Fire Accident Scenarios

Final Report

Manuscript Completed: December 2016

Date Published: March 2017

Prepared by:

J. A. Fort

J. M. Cuta

H. E. Adkins, Jr.

Pacific Northwest National Laboratory

P. O. Box 999

Richland, WA 99352

J. Piotter, NRC Project Manager

NRC Job Code J5710

Office of Nuclear Material Safety and Safeguards

NUREG/CR-7209

PNNL-24792

iii

ABSTRACT

This document summarizes studies of truck and rail transport accidents involving fires, relative 

to regulatory requirements for shipment of commercial spent nuclear fuel (SNF). These studies 

were initiated by the U.S. Nuclear Regulatory Commission in response to a 2006 National 

Academy of Sciences review of procedures and regulations. The fire accident scenarios were 

based on the severe historical railway and roadway fires in terms of their potential impact on 

SNF containers.

While no such accidents involving SNF have ever actually happened in shipments either by rail 

or roadway, accidents resulting in fires do occur in both modes of transport and, however 

unlikely, plausible arguments can be made for the possibility of SNF containers being involved 

in such accidents. A regulatory framework for SNF containers is in place in the United States 

(10 CFR 71) and internationally (International Atomic Energy Agency) to ensure that risk due to 

such accidents is small and that the danger to the public is within accepted standards. The 

history of this regulatory framework is briefly summarized.

The combined summary of this work on fire accidents demonstrates that current U.S. Nuclear 

Regulatory Commission regulations and packaging standards provide a high degree of 

protection to the public health and safety against releases of radioactive material in real-world

transportation accidents, were such events to involve SNF containers.

v

TABLE OF CONTENTS

ABSTRACT...............................................................................................................................iii

TABLE OF CONTENTS .............................................................................................................v

LIST OF FIGURES ...................................................................................................................vii

LIST OF TABLES......................................................................................................................ix

ACKNOWLEDGMENTS............................................................................................................xi

ABBREVIATIONS AND ACRONYMS .....................................................................................xiii

1.0 INTRODUCTION .............................................................................................................1-1

2.0 REGULATORY REQUIREMENTS FOR TRANSPORT OF SNF.....................................2-1

2.1 Genesis and Regulatory History ............................................................................ 2-1

2.1.1 Historical Background in the Development of Accident-Simulating 

Thermal Test.............................................................................................. 2-2

2.2 Summary of Current Regulations........................................................................... 2-4

2.2.1 Domestic Licensed Containers (CFR) ........................................................ 2-5

2.2.2 International Licensed Containers (IAEA)................................................... 2-6

3.0 ACCIDENT HISTORY, SAFETY FACTORS, AND TRANSPORT PLANS ......................3-1

3.1 Surveys of Rail and Truck Accidents ..................................................................... 3-1

3.1.1 Survey of Railway Accidents Involving Fires .............................................. 3-1

3.1.2 Survey of Roadway Accidents Involving Fires ............................................ 3-1

3.2 Rail Accidents in Perspective................................................................................. 3-2

3.2.1 Evaluation of Tunnel Fire Characteristics ................................................... 3-2

3.2.2 A Review of Rail Transportation Accidents................................................. 3-4

3.3 SNF Transport Plans ............................................................................................. 3-6

4.0 STUDIES TO EVALUATE ADEQUACY OF DESIGN REQUIREMENTS ........................4-1

4.1 Approach to Analysis of Fire Accident Scenarios................................................... 4-1

4.2 Numerical Models.................................................................................................. 4-2

4.2.1 Fire Dynamics Simulator ............................................................................ 4-2

4.2.2 COBRA-SFS.............................................................................................. 4-3

4.2.3 ANSYS....................................................................................................... 4-3

4.3 Seal Performance Testing ..................................................................................... 4-3

4.4 SNF Packages Included in Case Studies............................................................... 4-5

4.4.1 TransNuclear TN-68 SNF Transportation Package .................................... 4-5

4.4.2 HOLTEC HI-STAR 100 SNF Transportation Package................................ 4-7

4.4.3 NAC LWT SNF Transportation Package .................................................... 4-9

4.4.4 General Atomics GA-4 LWT SNF Transportation Package ...................... 4-11

5.0 ACCIDENT SCENARIOS INVOLVING SNF PACKAGES IN SEVERE FIRES................5-1

5.1 Baltimore Tunnel Fire ............................................................................................ 5-1

5.1.1 Description of the Baltimore Tunnel Fire .................................................... 5-1

5.1.2 Analysis of the Baltimore Tunnel Fire......................................................... 5-4

5.1.3 Accident Scenario for Baltimore Tunnel Fire .............................................. 5-5

5.2 Caldecott Tunnel Fire ............................................................................................ 5-8

5.2.1 Description of the Caldecott Tunnel Fire .................................................... 5-8

5.2.2 Analysis of the Caldecott Tunnel Fire....................................................... 5-10
vi

5.2.3 Accident Scenario for Caldecott Tunnel Fire ............................................ 5-12

5.3 MacArthur Maze Fire ........................................................................................... 5-14

5.3.1 Description of the MacArthur Maze Fire ................................................... 5-14

5.3.2 Analysis of MacArthur Maze Fire.............................................................. 5-16

5.3.3 Accident Scenario for MacArthur Maze Fire ............................................. 5-17

5.4 Newhall Pass Fire................................................................................................ 5-19

5.4.1 Description of the Newhall Pass Fire........................................................ 5-19

5.4.2 Analysis of the Newhall Pass Fire ............................................................ 5-21

5.4.3 Accident Scenario for Newhall Pass Fire.................................................. 5-21

6.0 ANALYSES OF FIRE ACCIDENT SCENARIOS .............................................................6-1

6.1 Analysis of Baltimore Tunnel Fire Accident Scenario ............................................. 6-1

6.2 Analysis of Caldecott Tunnel Fire Accident Scenario ............................................. 6-3

6.3 Analysis of MacArthur Maze Fire Accident Scenario.............................................. 6-7

6.3.1 Thermal Analysis of MacArthur Maze Accident Scenario ........................... 6-7

6.3.2 Structural Analysis of MacArthur Maze Accident Scenario ......................... 6-8

6.4 Analysis of Newhall Pass Fire Accident Scenario .................................................. 6-9

7.0 CONSEQUENCES OF FIRE ACCIDENT SCENARIOS ..................................................7-1

7.1 Consequences of Baltimore Tunnel Fire Accident Scenario................................... 7-1

7.2 Consequences of Caldecott Tunnel Fire Accident Scenario................................... 7-2

7.3 Consequences of MacArthur Maze Fire Accident Scenario ................................... 7-3

7.4 Consequences of Newhall Pass Fire Accident Scenario........................................ 7-7

8.0 CONCLUSIONS AND RECOMMENDATIONS................................................................8-1

9.0 REFERENCES ................................................................................................................9-1

10.0 APPENDIX - RESPONSES TO PUBLIC COMMENTS ON NUREG/CR-7209...............10-1
vii

LIST OF FIGURES

3.1 Radioactive Material Rail Shipment..............................................................................3-3

3.2 Rolling Stock, Escort, and Buffer Car Schematic (Figure ‘E’ in DOE 2009)...................3-7

4.1 Cross-section of TN-68 Package (drawing 972-71-3 Rev. 4, “TN-68 Packaging 

General Arrangement: Parts List and Details”) .............................................................4-6

4.2 Exterior View of TransNuclear TN-68 Spent Fuel Transportation Package with 

Impact Limiters Installed...............................................................................................4-7

4.3 HOLTEC HI-STAR 100 Spent Fuel Package................................................................4-8

4.4 Spent Fuel Transportation Package on Railcar.............................................................4-9

4.5 NAC LWT Transport Package (without ISO Container) ..............................................4-10

4.6 NAC LWT Transport Package (with ISO Container) ...................................................4-11

4.7 GA-4 Package: Exploded View (General Atomics 1998) ............................................4-12

5.1 Dimensions of Howard Street Tunnel with Tank Car on Track......................................5-2

5.2 Liquid Tripropylene Tank Car .......................................................................................5-2

5.3 Puncture in Tank Car....................................................................................................5-3

5.4 Peak Transient Ambient Air Temperatures in FDS Simulation of Baltimore Tunnel 

Fire Accident Scenario (Smoothed Values, NIST 20-m Data).......................................5-6

5.5 Peak Transient Tunnel Surface Temperatures for Floor, Walls, and Ceiling in 

FDS Simulation of Baltimore Tunnel Fire Accident Scenario (Smoothed Values, 

NIST 20-m Data) ..........................................................................................................5-7

5.6 Peak Transient Horizontal Velocities near Package Surface in FDS Simulation of 

Baltimore Tunnel Fire Accident Scenario (Smoothed Values, NIST 20-m Data) ...........5-8

5.7 West Portal of Caldecott Tunnel ...................................................................................5-9

5.8 Cross-section Diagram of Bore No. 3 of Caldecott Tunnel..........................................5-10

5.9 Evolution of Ceiling Centerline Temperatures in FDS Simulation of Caldecott 

Tunnel Fire .................................................................................................................5-11

5.10 Evolution of Gas Velocity Profile near Ceiling Centerline in FDS Simulation of 

Caldecott Tunnel Fire .................................................................................................5-12

5.11 Peak Surface Temperatures in 3-hour FDS Simulation of Caldecott Tunnel Fire........5-13

5.12 Peak Gas Temperatures in 3-hour FDS Simulation of Caldecott Tunnel Fire .............5-13

5.13 Peak Gas Velocities in 3-hour FDS Simulation of Caldecott Tunnel Fire ....................5-14

5.14 Roadway Configuration after the MacArthur Maze Fire (photo from MAIT Report, 

CHP 2007a)................................................................................................................5-15

5.15 Estimated Fire Pool for Pre- and Post-collapse Portion of the MacArthur Maze Fire...5-17

5.16 Aerial View of Roadway Configuration Showing Location of Newhall Pass Tunnel

(image extracted from the CHP MAIT report [CHP 2007b]) ........................................5-20

5.17 Boundary Temperatures for Thermal Analysis of SNF Package in Newhall 

Pass Fire Scenario at “Most Adverse” Vehicle Locations for Case NIST-01 ...............5-23

6.1 NAC LWT Package Component Maximum Temperature Histories for First 30 hours 

of Fire Transient – Baltimore Tunnel Fire Accident Scenario ........................................6-3

6.2 NAC LWT Package (with ISO Container): Component Maximum Temperature 

Histories during Fire Transient – Caldecott Tunnel Fire Accident Scenario...................6-5

6.3 NAC LWT Package (without ISO Container): Component Maximum Temperature 

Histories during Fire Transient – Caldecott Tunnel Fire Accident Scenario...................6-5
viii

6.4 GA-4 Package Peak Component Temperatures Predicted with ANSYS Model for 

Post-fire Cooldown to 6.5 hours – MacArthur Maze Fire Accident Scenario .................6-8

6.5 GA-4 Package Maximum Temperatures in All Cases for “Hottest Fire” – Newhall 

Pass Fire Accident Scenario.......................................................................................6-10

6.6 GA-4 Package Comparing Maximum Temperatures in All Cases for “Longest 

Fire” – Newhall Pass Fire Accident Scenario..............................................................6-11

7.1 Predicted Burst Rupture Temperature Compared to Maximum Fuel Rod 

Temperatures from Thermal Analysis Models – Newhall Pass Fire 

Accident Scenario ........................................................................................................7-8

7.2 Cavity Gas Pressure for Bounding Cases for Newhall Pass Tunnel Fire Scenario 

Compared to Bounding Value from the MacArthur Maze Fire Scenario......................7-11
ix

LIST OF TABLES

2.1 Insolation Data .............................................................................................................2-5

5.1 Comparison of Various Hydrocarbon Liquids................................................................5-4

5.2 FDS Cases Modeling Newhall Pass Tunnel Fire ........................................................5-22

5.3 Peak Fire Boundary Temperatures at “Hottest Fire” and “Longest Fire” Locations .....5-22

6.1 GA-4 Package Maximum Peak Fuel Cladding Temperatures for All Cases –

Newhall Pass Fire Accident Scenario .........................................................................6-10

7.1 Time above Predicted Rod Rupture Temperatures in the MacArthur Maze 

Fire Scenario................................................................................................................7-5

7.2 Results of Fuel Performance Analyses in the Newhall Pass Fire Scenario ...................7-8

7.3 Summary of Peak Lid Seal Temperatures during Phases of Transient in the 

Newhall Pass Fire Accident Scenario ...........................................................................7-9

xi

ACKNOWLEDGMENTS

PNNL wishes to thank Christopher Bajwa of the International Atomic Energy Agency (IAEA) for 

providing a copy of their draft report, Technical Basis for the IAEA Regulations for the Safe 

Transport of Radioactive Material, and for permission to use the section on historical 

background of the accident-simulating thermal test in our report. The contributions of Earl 

Easton of the U.S. Nuclear Regulatory Commission (NRC) (who provided the summary of 

transportation safety studies that we borrowed from the Baltimore tunnel fire report) were also 

invaluable in appropriately quantifying the risk of severe fire accidents in rail transportation.

The authors also appreciate the efforts of technical communications staff Colleen Winters and 

Susan Tackett, in making this a clear and concise presentation of our work.

xiii

ABBREVIATIONS AND ACRONYMS

AAR Association of American Railroads

ADAMS Agencywide Documents Access and Management System

AEC Atomic Energy Commission

BWR boiling water reactor

CFD Computational Fluid Dynamics

CFR Code of Federal Regulations

CHP California Highway Patrol 

CRUD Chalk River Unknown Deposit (generic term for various residues 

deposited on fuel rod surfaces, originally coined by Atomic Energy of 

Canada, Ltd. (AECL) to describe deposits observed on fuel removed from 

the test reactor at Chalk River.)

DOE U.S. Department of Energy

DOT U.S. Department of Transportation

EPDM ethylene-propylene (diene monomer)

FDS Fire Dynamics Simulator (computational fluid dynamics computer code)

FRA Federal Railroad Administration

HAC Hypothetical Accident Conditions

HAZMAT Hazardous Material

HLW high level waste

IAEA International Atomic Energy Agency

ISO International Organization for Standardization (The International 

Organization for Standardization has decreed the use of the initials ISO 

for reference to the organization, regardless of the word order of the 

organization’s name in any given language. This defines a uniform 

acronym in all languages.)

LWT legal-weight truck

MAIT Multi-Discipline Accident Investigation Team 

MPC Multi-Purpose Canister

NAC Nuclear Assurance Corporation 

NAS National Academy of Sciences

NCT Normal Conditions of Transport

NIST National Institute of Standards and Technology

NRC U.S. Nuclear Regulatory Commission

NTIS National Technical Information Service

NTSB National Transportation Safety Board

NUREG U.S. Nuclear Regulatory Guide 

PCT Peak Cladding Temperature 

PTFE polytetrafluoroethylene

PWR pressurized water reactor

SAR safety analysis report

SNF spent nuclear fuel

TFE tetraflouro-ethylene

1-1

1.0 INTRODUCTION

This document summarizes recent studies of truck and rail transport accidents involving fires 

relative to regulatory requirements for shipment of commercial spent nuclear fuel (SNF). The 

U.S. Nuclear Regulatory Commission (NRC) has conducted case studies for accident scenarios 

involving the most severe fires and results have been compared with existing requirements of 

SNF containers. Safe transport of SNF is also dependent on effective procedures and 

administrative controls, such as the NRC requirements governing planning and security of SNF 

shipments1

, however these topics are not addressed in this report. 

While no such accidents involving SNF have been documented, for shipments either by rail or 

truck, accidents resulting in fires do occur in both modes of transport and, however unlikely, 

plausible arguments can be made for the possibility of SNF containers being involved in some 

future accidents. A regulatory framework for SNF containers is in place here in the United 

States (10 CFR 71 2012) and internationally (IAEA 2012) to ensure that risk due to such 

accidents is small and that the danger to the public is within accepted standards. 

For the most part, the requirements for SNF package performance in a fire accident have 

remained unchanged since 1964. Specifically, the requirement is survivability (meaning no 

release above regulatory limits) in an 800°C fire for 30 minutes. This fire temperature and 

duration bounds a broad range of possible fire exposures for a transportation package, but 

surveys of rail and roadway accidents involving fires show a small number of severe fires in 

which the peak fire temperature and duration have exceeded these regulatory values. The NRC 

and others have conducted analyses for a number of these severe fires to investigate the 

response and potential consequences if an SNF package had been involved (NUREG/CR-6886 

2009; NUREG/CR-6894 2007, NUREG/CR-7206 2015, NUREG/CR-7207 2015). Results of 

these analyses have been useful in assessments of the adequacy of the current definition of the

regulatory fire to protect public health and safety. 

The adequacy of regulations for managing SNF transportation risks has been investigated by 

the National Academy of Sciences (NAS), and was documented in their 2006 report, Going the 

Distance? The Safe Transport of Spent Nuclear Fuel and High-Level Radioactive Waste in the 

United States (NAS 2006). Among the materials reviewed by the investigating committee was 

an early and very conservative analysis by the NRC based on the 2001 Howard Street Tunnel 

fire in Baltimore (also known as the Baltimore tunnel fire), which resulted from derailment of a 

train carrying hazardous materials. This analysis of a hypothetical SNF package response 

considered package exposure to maximum temperatures for up to 150 hours. Subsequent 

detailed analyses of the accident showed that the fire could have burned for no more than 3 to 

12 hours before being extinguished, and due to poorly ventilated conditions within the tunnel,

the peak temperature in the flaming region was estimated to have lasted for less than an hour 

(NUREG/CR-6886 2009). The reviewers acknowledged the significant conservatisms contained 

in the earlier analysis. One of the recommendations of the NAS report was that,

• NRC “undertake additional analyses of very long-duration fire scenarios that bound 

expected real-world accident conditions.”

The NAS committee was provided, but did not have time to review, draft results of a more 

plausible scenario of a well-ventilated version of the Howard Street Tunnel fire lasting only 

7 hours (NUREG/CR-6886 2009). That study was a significant response to the NAS 

 1 See 10 CFR 73.37, Requirements for physical protection of irradiated reactor fuel in transit.
1-2

recommendation. NRC followed this with analyses of three additional severe fires that are 

expected to bound real-world accident conditions for road and railway transport of SNF 

(NUREG/CR-6894 2007; NUREG/CR-7206 2015; NUREG/CR-7207 2015). The results of 

these four studies are discussed in detail in this report.

Section 2.0 of this report begins with a description of SNF transport package regulatory 

requirements pertaining to accidents involving fire, and the historical background behind them. 

Section 3.0 summarizes the results of NRC commissioned surveys of truck and rail transport 

accidents involving fires. Section 4.0 describes the approach to assessing SNF package 

response in hypothetical fire accident scenarios. Section 5.0 provides a detailed summary of 

NRC accident scenarios corresponding to four of these severe fires, one of which occurred in a 

rail tunnel. The other three involved trucking accidents, two of which occurred in roadway 

tunnels, and the third occurred in a stacked layer of freeway interchange ramps. Section 6.0

gives a brief summary of analyses performed to determine package response in each scenario. 

Consequences in terms of radiation exposure and radioactive material release are discussed in 

Section 7.0. In Section 8.0, conclusions and recommendations are provided regarding the 

results of these and other case studies relative to the adequacy of the current regulatory 

requirements for truck and rail transport of SNF. This evaluation considers the frequency of 

occurrence and variety of historical accidents, as well as the severity of the fires involved. 

References are provided at the end of this report.
2-1

2.0 REGULATORY REQUIREMENTS FOR

TRANSPORT OF SNF

The summary here is limited to SNF, which by definition requires a Type B package, since spent 

fuel assemblies contain in excess of the amount of radioactive material permitted in a Type A 

package. A Type B package can carry more radioactive material than is permitted in a Type A 

package and must retain the integrity of containment and shielding under normal conditions of 

transport (as per 49 CFR 173), and meet specified release limits for hypothetical accident 

conditions. 

2.1 Genesis and Regulatory History

The early regulatory history for radioactive material transport regulation was laid out in a 

proposed rule for air transport1 that was included in NUREG-0170 (Final Environmental 

Statement on the Transportation of Radioactive Material by Air and Other Modes):

• These regulations had begun with the Interstate Commerce Commission in 1948 and were 

based on a report by National Academy of Sciences-National Research Council 

Subcommittee on Transportation of Radioactive Material. Preceding this was the ban on 

“shipment of radioactive material by mail in 1936 to protect unexposed film.” The Interstate 

Commerce Commission regulations were adopted with small changes by the International 

Atomic Energy Agency (IAEA) in 1961. Evolution since then saw revised standards by the 

IAEA to incorporate specific accident damage test standards, which were adopted by the 

Atomic Energy Commission (AEC) and U.S. Department of Transportation (DOT) (under 

the Interstate Commerce Commission) by 1968. Apart from changes to deal with leak 

testing of shipments of liquids, handling and inspection procedures, and “restrictions on 

shipment of plutonium on passenger aircraft,” regulations have remained unchanged since 

that time. 

• Spent fuel transport, due to radioactive material quantity, falls under the category of a 

Type B package. In a memorandum of understanding between the DOT and AEC in 1968, 

which was revised in 1973, the AEC [now NRC] “develops performance standards for 

package designs and reviews package designs for Type B fissile and large-quantity 

packages.” 

• As to the relationship between various regulators, it is stated that, “DOT requires AEC (now 

NRC) approval prior to use of all Type B, fissile and large-quantity package designs. DOT 

is the National Competent Authority with respect to foreign shipments under the IAEA 

transport standards. IAEA Certificates of Competent Authority are issued by DOT with 

technical assistance provided by NRC as requested.”

• For air shipments, it is stated that containers are required to satisfy drop and puncture tests 

as well as a 30-minute fire at 1475°F and a 3-ft. water immersion test for eight hours. 

The fire test standard noted here remains the same today for SNF transport containers. A 

historical background for that standard is provided in the next section.

 1 PROPOSED RULES, NUCLEAR REGULATORY COMMISSION [10 CFR Parts 71 and 73] RADIOACTIVE 

MATERIAL, Packaging and Transportation by Air, Federal Register, Vol. 40, No. 104-Monday, June 2, 1975.
2-2

2.1.1 Historical Background in the Development of Accident-Simulating Thermal Test2

In considering potential fire environments, Messenger and Fairbairn (1963) indicate that the 

IAEA’s Panel considered the frequencies, probabilities, and many other factors that can work 

together in defining the environment a package might experience in a severe accident. These 

included:

• types of fuel, quantities of fuel, rate of spillage of fuel, and dispersal of spilled fuel; 

• possible ranges of temperatures in a fire, and associated effects of size of fuel source and 

effects of oxygen supply (wind); 

• duration of fires; and

• size and mass of the package.

It was recognized that the maximum temperatures achieved in a fire are typically the result of a 

“local torching,” which would not provide a significant threat to large packages due to the 

localized nature of the heat source. Further, they noted that melting of materials could be a 

reasonable indicator of effective or average flame temperatures, for which it was shown that 

large fires in railway accidents had resulted in the following:

• zinc (with melting point of 419°C) was melted, 

• aluminum (with melting point of 660°C) was partially melted, 

• glass (with melting point of about 1000°C) sagged but was not melted, and 

• steel (with melting point of 1500°C) was not melted.

After consideration of the data presented, and tests (both open-fire and oven environments) that 

were then being used, and noting that some of these tests precluded any intervention (i.e.,

quenching of burning packaging elements) following thermal exposure until package 

temperatures had begun to drop, it was recommended the test include exposure “to a furnace 

temperature of 800°C for 30 minutes with no quenching until after the temperature of the interior 

has started to fall.”

In elaborating on the discussion relative to the thermal test, Appleton and Servant (1964) stated 

that there “was considerable discussion on the kind of fire to which a package might be 

exposed. The majority opinion was in respect of a large conflagration as might occur when a 

tank of petrol or kerosene spilled and took fire, but reference was also made to “torching” flames 

from a ruptured compressed gas tank vehicle. Temperatures in the order of 1000°C were 

considered relevant.” They further noted that reported tests in open fires provided thermal 

environments very similar to those attained in hot wall, 800°C oven tests. It was further noted 

(Appleton and Servant 1964, Fairbairn and George 1966) that the basis for the average 

temperature was initially established using work of various individuals, including that of 

Bader (1965) where, following the detailed analysis of a number of open pool fire tests and 

consideration of work of others, he concluded: “an exact prediction of temperatures expected in 

a particular fire cannot be made. Examination (of data) which shows the wide range of fire 

environments measured in “similar” fires, indicates the difficulty one would have in predicting the 

temperatures expected in a given fire. On the other hand, the range of fire temperatures to be 

expected can be stated with some certainty, and over a large number of tests, the fire 

temperatures will produce an average. This average turns out to be approximately 1850°F.”

 2 This section (with same title) is taken verbatim from IAEA draft report: Pope, Ronald B., Dennis Mennerdahl and 

Christopher S. Bajwa, Technical Basis for the IAEA Regulations for the Safe Transport of Radioactive Material 

(SSR-6). 12 September 2013 draft provided in 21 May 2014 email from C.S. Bajwa to H.E. Adkins.
2-3

The average temperature of 1850°F proposed by Bader equates to 1010°C. The average fire 

temperature of 1010°C is, of course, higher than the 800°C that was ultimately used in the early 

regulations, and continues to be used today. Fairbairn and George (1966) stated that severe 

transport fires “seldom last more than half an hour, ... and information on the temperatures 

attained suggests that although flame temperatures of liquids such as petrol can be about 

1000°C, such peak temperatures are reached only very locally by metallic material involved in 

the fire.”

Following much deliberation, the experts felt it necessary to consider all factors in establishing 

the thermal test condition, not just the maximum average attainable temperature in a “perfect” 

fire situation. The ramifications of accounting for multiple, “real-life” parameters were 

considered including, inter alia: (a) radiant, conductive, and convective heat inputs; and 

(b) exposure scenarios, which require specification of:

• an effective source (i.e., flame) temperature and effective flame thickness where, for pool 

fuel fires, this requires consideration of such parameters as: fuel type, size of package, 

mass of package, size of pool (too small and the flame is not luminous, too large and the 

flame suffers from oxygen starvation), location of package above the pool, and wind effects; 

• emissivity coefficient of the heat source (i.e., the flame and its luminosity);

• absorption coefficient of the package surface; 

• duration of exposure; 

• support of the package at specified height; and 

• whether the package should be cooled following termination of heat source exposure.

These deliberations resulted in inclusion of the statement in the regulations that any thermal test 

shall be considered as satisfactory provided that the parameters for satisfying the test were then 

specified in terms of: 

• source temperature (800°C), 

• duration of test (30 min), 

• source emissivity (0.9), 

• package surface absorptivity (0.8), 

• flame thickness of not less than 0.7 m (2 ft) and not more than 3 m (10 ft), 

• the flame must surround the package during the entire test, and 

• there would be no intervention after exposure to the thermal source until the inner

components of the package began to cool.

A panel of technical experts convened in mid-1964 (IAEA, Servant and Capet 1964) deliberated 

on the many issues associated with the thermal test. On pages 2 through 14 of Notes on the 

Panel Meeting on the Design and Testing of Packaging for Radioactive Materials (IAEA, 

Servant and Capet 1964) deliberations based on inputs from the U.S., the U.K. and the 

Eurochemic Company are documented. Issues addressed included (a) open pool fire tests 

versus oven tests, (b) the size of the package versus the size of the open pool and the size of 

the oven, (c) the thickness of a luminous flame, (d) the temperature to be reached by the 

package in the test and the length of time it should be required to remain at that temperature, 

(e) the heat input to the package, (f) the coefficient of emissivity of the flame or furnace wall, 

(g) the coefficient of absorption of heat by the package surface, (h) whether high humidity could 

depress the flames in an open pool test, (i) the effect of wind upon flames in an open pool fire, 

(j) the height of the bottom of a package above the fuel reservoir, (k) the choice of fuel for a pool 
2-4

fire, (l) the depth of the fuel in the pool and its effect on the height of the walls of the pool 

retention system, and (m) whether to allow mechanical cooling of the package immediately 

following termination of the fire test.

From this extensive discussion, it was recommended by that panel of experts that the text for 

the fire test for the 1964 Edition of the Regulations be written as follows:

“Any thermal test employed shall be considered satisfactory provided that the 

heat input to the package is not less than that which would result from the 

exposure of the whole package to a radiation environment of 800°C for 

30 minutes with an emissivity coefficient of 0.9 assuming the surfaces of the 

packages had an absorptive coefficient of 0.8.”

Fairbairn and George (1966) discussed the positioning of the package so that its lower surface 

would be 1 m above the surface of the burning fuel, and that the package should be supported 

“such that it does not prevent direct exposure of any significant area of the package to the heat 

generated,” with a view to ensuring maximum damage to the test package. They further 

emphasized that an open-fire test method or appropriate furnace test methods that are “equally 

considered to meet the requirements of the general specifications. There are two main 

advantages in giving this open-fire test; first it can be conducted with relative ‘home-made’ 

facilities without the need for much detailed work by highly qualified scientific personnel, and 

second, the conditions of an open-fire have the merit of being seen to be similar, in their 

essential aspects, to those of an actual transport fire.”

With minor changes in wording, this is essentially the test that exists in paragraph 728 of SSR-6 

(IAEA 2012) today; and much of the discussion contained in Appleton and Servant (1964) has 

been included in the advisory material on this test contained in TS-G-1.1 (IAEA 2008, 2011).

They further discussed the fire duration, noting that “... when the actual heat input to the interior 

of the package is examined it can be shown, particularly for large packages, that a test involving 

a 30 min period of exposure to heat input, and a subsequent natural cooling period until the 

innermost temperature has started to fall before any artificial cooling is applied, might well be 

more severe in its effect on the package than one in which heat is applied for 60 min according 

to a specified time-temperature curve with artificial cooling applied immediately afterwards.”

Another topic addressed in the 1964 panel discussions (Appleton 1964) was whether or not to 

allow artificial cooling of the package following thermal exposure. It was agreed that this would 

not be allowed. Specifically, the experts noted “there is a considerable body of opinion that the 

post exposure conditions up to thermal equilibrium, prohibiting the use of artificial cooling, 

should also be specified.”

2.2 Summary of Current Regulations

The regulations for packages designed for domestic SNF transport are described in the Code of 

Federal Regulations (CFR), specifically under Title 10 (Energy), Chapter 1 (Nuclear Regulatory 

Commission), Part 71 (Packaging and Transportation of Radioactive Material), or more

commonly, 10 CFR 71. Those parts of the CFR relevant to fire accidents are summarized 

below. Additionally, as described in Section 2.1, internationally licensed containers are 

regulated by the IAEA standards and these are substantially the same. These are referenced 

briefly in Section 2.2.2 below.
2-5

2.2.1 Domestic Licensed Containers (CFR)

Regulatory requirements pertaining to fire accidents are found in 10 CFR 71, Subpart F –

Package, Special Form, and LSA-III Tests. Section 71.73, “Hypothetical Accident Conditions,”

deals with this topic specifically, but Section 71.71, “Normal Conditions of Transport,” is 

commonly referenced in accident analyses, and is referenced in this report, since it dictates the 

initial conditions for the package accident condition.

Section 71.71, Normal Conditions of Transport, which is referred to as Normal Conditions of 

Transport (NCT) in this report and related references, specifies (b) “Initial Conditions” for 

ambient temperature and initial internal pressure within the containment prior to NCT tests. The 

temperature preceding and following a test is to be held constant “at that value between -29°C

(-20°F) and 38°C (100°F) which is most unfavorable for the feature under consideration.” 

Internal pressure within the containment is to be the maximum normal operating pressure, 

unless a lower pressure, consistent with the ambient temperature considered for a test, is more 

unfavorable. For conservative analysis of a fire accident, the choice of initial condition is the 

highest temperature in this range and the initial condition for containment pressure is the 

maximum normal operating value. This initial condition is called out specifically in Section 71.71 

as the first item under (c) “Conditions and Tests,”

1. Heat. An ambient temperature of 38°C (100°F) in still air, and insolation according to the 

following table:

Table 2.1. Insolation Data

Form and location of surface

Total insolation for a 12-hour 

period (gcal/cm2)

Flat surfaces transported horizontally:

Base None

Other surfaces 800

Flat surfaces not transported horizontally 200

Curved Surfaces 400

Section 71.73, Hypothetical Accident Conditions, or HAC, repeats the same temperature range 

and internal pressure requirements under (b) Test Conditions, which is perhaps why reference 

is instead made to use of the “Hot” NCT conditions for initial conditions of a fire accident 

analysis. The tests in this section, which include 1) Free drop, 2) Crush3

, 3) Puncture, 

4) Thermal, and 5) Immersion, are to be carried out sequentially, except that an undamaged 

package can be used for the immersion test. The conditions for the HAC Thermal test are 

detailed and, as the subject of this report, are repeated here for reference:

“Exposure of the specimen fully engulfed, except for a simple support system, in 

a hydrocarbon fuel/air fire of sufficient extent, and in sufficiently quiescent 

ambient conditions, to provide an average emissivity coefficient of at least 0.9, 

with an average flame temperature of at least 800°C (1475°F) for a period of 

30 minutes, or any other thermal test that provides the equivalent total heat input 

to the package and which provides a time averaged environmental temperature 

of 800°C. The fuel source must extend horizontally at least 1 m (40 in), but may 

not extend more than 3 m (10 ft), beyond any external surface of the specimen, 

and the specimen must be positioned 1 m (40 in) above the surface of the fuel 

 3 This test is excluded for SNF packages.
2-6

source. For purposes of calculation, the surface absorptivity coefficient must be 

either that value which the package may be expected to possess if exposed to 

the fire specified or 0.8, whichever is greater; and the convective coefficient must 

be that value which may be demonstrated to exist if the package were exposed 

to the fire specified. Artificial cooling may not be applied after cessation of 

external heat input, and any combustion of materials of construction, must be 

allowed to proceed until it terminates naturally.”

This HAC Thermal test or HAC Fire presents a significant design test for SNF packages. In 

Section 3.0, survey results of actual fires are compared to this regulatory fire definition and 

some of the historical fires are found to be, in some aspect, more severe than the regulatory 

fire.

2.2.2 International Licensed Containers (IAEA)

The regulatory requirements for internationally licensed containers are described in the IAEA 

document, SSR-6, Regulations for the Safe Transport of Radioactive Material (IAEA 2012). The 

equivalent definitions to package tests in 10 CFR 71 are found under Section VII, “Test 

Procedures” and within that section under “Tests for Packages.” The equivalent definitions for 

NCT tests are found under the sub-heading, “Tests for demonstrating ability to withstand normal 

conditions of transport.” References within this document are given by numbered paragraphs,

and the specific paragraphs for NCT are numbered 719 through 724. The equivalent tests for 

HAC follow under the sub-heading, “Tests for demonstrating ability to withstand accident 

conditions of transport” and the associated paragraphs are numbered 726 to 729. Although 

wording differs, the test requirements are identical to those in 10 CFR 71. 

Design and testing requirements for specific package types are detailed in Section VI, 

“Requirements for Radioactive Material and for Packagings and Packages.” For example, 

requirements for Type B(U) packages are specified in part under paragraph 653:

653. A package shall be so designed that, under the ambient conditions specified 

in paras 656 and 657, heat generated within the package by the radioactive 

contents shall not, under normal conditions of transport, as demonstrated by the 

tests in paras 719–724, adversely affect the package in such a way that it would 

fail to meet the applicable requirements for containment and shielding if left 

unattended for a period of one week.

As noted above, paras 719 – 724 define the NCT tests. The “ambient conditions specified in 

paras 656 and 657” are the temperature (38°C) and solar insolation, respectively, and these are 

identical to those spelled out for the NCT Heat condition under 10 CFR 71. 

Finally, the equivalent specification for internal containment pressure is given in paragraph 663:

663. A package shall be so designed that if it were at the maximum normal 

operating pressure and it were subjected to the tests specified in paras 719–724 

and 726–729, the levels of strains in the containment system would not attain 

values that would adversely affect the package in such a way that it would fail to

meet the applicable requirements.

The NCT tests are again cited here, and the HAC tests (paras 726 – 729) are also included. 
2-7

Notwithstanding a different approach to writing, this comparison between IAEA and CFR 

requirements shows that equivalent thermal requirements are made for SNF packages when 

licensed in the U.S. or internationally. More specifically and relative to the topic of this report, 

the definition of the HAC Thermal test or HAC Fire is equivalently specified and recognized

worldwide.

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3.0 ACCIDENT HISTORY, SAFETY FACTORS,

AND TRANSPORT PLANS

This section presents accident statistics from NRC studies to illustrate the frequency and 

severity of fire accidents in rail and roadway transport of cargo of all types. It is shown that 

severe fire accidents are very rare. A description of design factors and administrative controls is 

provided to indicate why fire accidents involving SNF are especially unlikely in rail transport. 

Lastly, elements of SNF shipment plans are discussed, which rely on this mode of transport.

3.1 Surveys of Rail and Truck Accidents

The NRC completed surveys of truck and rail accidents (NUREG/CR-7034 2011, NUREG/CR7035 2011). These studies had a common objective, which was to determine the types and 

frequency of accidents involving severe, long-duration fires that could impact transport of SNF. 

The motivation for these studies was the recommendation by the NAS committee (NAS 2006)

for NRC to analyze fires that exceed the 30-minute duration of the hypothetical accident 

condition in 10 CFR 71. The results of the railway accident survey are summarized in 

Section 3.1.1 and the summary for roadway accidents is provided in Section 3.1.2. 

3.1.1 Survey of Railway Accidents Involving Fires

In this NRC commissioned study (NUREG/CR-7034 2011), databases analyzed included those 

from the Federal Railway Administration and the DOT – Pipeline and Hazardous Materials 

Safety Administration. The study found that the number of accidents involving the release of 

hazardous material has been decreasing and, because of that, accident data from a 12-year

period (1997 to 2008) were used to calculate accident rates at the time the document was being 

written. 

When analyzing these databases, it was not possible to identify whether or not a fire was fully 

engulfing, as defined in 10 CFR 71. The approach taken in this study (NUREG/CR-7034 2011)

was to identify historic railway fires as a severe fire if they had a reasonable potential to 

approach a fully engulfing fire under the 10 CFR 71 definition. In their analysis, the two criteria 

for this were, 1) that a railcar “must have been substantially engulfed in a fire that persists for an 

extended period of time”, and 2) that the principal source of fuel for the substantially engulfing 

fire must have been derived from another railcar.” 

Using the railway accident data from a 12-year period (1997 to 2008) and this definition of 

severe fires, only nine such accidents were identified. (The specific causes were not identified 

for these nine accidents.) The occurrence of nine accidents over twelve years was used by the 

authors to estimate a frequency of occurrence of severe railway fire accidents of 6.2x10-4

accidents per million freight train-km (1x10-3 accidents per million freight train-mi). 

3.1.2 Survey of Roadway Accidents Involving Fires

This NRC commissioned study (NUREG/CR-7035 2011) examined data from the DOT –

Pipeline and Hazardous Materials Safety Administration. The surveyed data was limited to a 

12-year period (1997 to 2008), matching the final interval for the railway study (NUREG/CR7034 2011). Initial screening was for accidents involving more than one vehicle, with one or 

both carrying hazardous materials.
3-2

Accidents in the initial screening were examined further to identify those severe enough to 

potentially affect an SNF package on another vehicle. This selection was based on the 

following criteria: 1) the principal source of fuel for the fire was from another vehicle, 2) the fuel 

was a flammable liquid that could pool beneath another vehicle, 3) multiple vehicles were 

involved, and 4) the fire lasted for an extended period of time (defined in the study as at least 

30 minutes). Because information about accidents typically did not include fire duration, this last 

criterion was based on a released volume of fuel sufficient to burn in a pool fire for at least 

30 minutes. Collisions with a train were not included. 

A total of 23 severe fire accidents out of more than 23,106 in-transit Hazardous Material 

(HAZMAT) accidents were identified using these criteria. Together with vehicle mileage data 

from the U.S. Census Bureau and the Bureau of Transportation Statistics, the frequency of 

occurrence of severe roadway fire accidents was estimated at 4.9x10-5 accidents per million 

HAZMAT vehicle-km (7.89x10-5 accidents per million HAZMAT vehicle-mi). In the study of 

trends in these 23 accidents, no dominant cause was identified. 

3.2 Rail Accidents in Perspective

This report describes results of the NRC study of the Baltimore tunnel fire accident scenario 

along with three other studies of accident scenarios based on historical severe fire accidents. 

The Baltimore tunnel fire study is the only railway accident scenario in this group, and as part of 

background, NRC described salient features of a railway tunnel fire and provided a summary of 

railway accidents and factors that will further lessen the potential for any fire accident involving 

SNF. The following two sections are taken from the Baltimore tunnel fire report (NUREG/CR6886 2009).

3.2.1 Evaluation of Tunnel Fire Characteristics

The 30-minute fully engulfing fire prescribed in the current NRC regulations defines a bounding 

fire for essentially all credible fire accidents involving SNF shipping packages. A fully engulfing 

open pool fire would generally be expected to subject a package to the hottest possible 

conditions for a given fuel supply. However, when considering potential accidents involving rail 

transport of SNF or high level waste (HLW), it is arguable that a rail tunnel fire could also 

present one of the more severe thermal challenges to a spent fuel transportation package. This 

is one of the reasons the staff chose to study the Baltimore tunnel fire event.

In examining real-world accidents that could involve a spent fuel transportation package, a 

number of significant differences are apparent between tunnel fires and severe fires occurring in 

an open (non-tunnel) environment. These factors include: 1) the possible position of a spent 

fuel package in relation to the fire location; 2) the nature of the flammable material involved; 

3) the rail bed materials; 4) the types of fires that can occur and; 5) emergency response to fire 

accidents.

In a fully engulfing fire, in which the fuel is generally assumed to form a pool, the most severe 

conditions, by definition, occur in the hottest flaming region of the fire. In a typical regulatory fire 

analysis (defined by the fire conditions in 10 CFR 71.73), an SNF package is assumed to be 

located within the flaming region of the fire 3.3 ft (1 meter) above the surface of the pool. 

However, because many railroad tracks are elevated above grade and are constructed on 

porous substrate, pooling of spilled flammable liquid is less likely in an open environment when 

compared with a tunnel environment, where the rail bed surface is often rock, concrete, or 
3-3

pavement. In fact, many of the fires resulting from rail accidents have involved the leakage of 

flammable gas (such as propane), rather than a liquid. A flammable gas cannot form a pool. If 

ignited, flammable gas leaking from a tank car will generally result in a localized pressure fire 

that is incapable of engulfing a spent fuel transportation package.

In a rail accident involving a fire, it is extremely unlikely that a spent fuel transportation package 

would end up directly adjacent to a tank car carrying flammable liquid. Federal regulations 

issued by the DOT, in 49 CFR 174.85, require very specifically defined spacing between rail 

cars carrying radioactive materials and hazardous materials of any kind, including flammable 

liquids. Typical requirements specify that a rail car carrying radioactive material must be 

separated from cars carrying other hazardous material by at least one buffer car. A rail car 

carrying a spent fuel package would not be coupled directly to a tank car carrying flammable or 

combustible liquid. Figure 3.1 shows an example of a buffer car arrangement in an actual 

radioactive material shipment by rail.

Figure 3.1. Radioactive Material Rail Shipment

The location of the spent fuel package relative to the fire, for a fire in an open environment (i.e., 

a non-tunnel fire), will determine the amount of heat absorbed by the package (assuming a 

direct exposure to the fire). This is because thermal radiation is the main mechanism1 for heat 

transfer from the fire to the package. In an open environment, the energy imparted to the 

package from the fire falls off rapidly with distance from the fire. In a tunnel environment, by 

contrast, the fire may result in elevated temperatures on adjacent tunnel surfaces, which could 

 1 For a discussion of this phenomenon see NUREG/CR-4892, Shipping Container Response to Severe Highway and 

Railway Accident Conditions, Vol. II, pages 175 to 178.
3-4

result in a package being subjected to an “oven” effect due to heat radiating from hot tunnel 

surfaces for an extended period of time, possibly for several hours after the fire has been 

extinguished. 

In rail accidents involving fires and hazardous materials in tank cars (including flammable gas or 

liquid), emergency responders follow the DOT Emergency Response Guidebook2

. Emergency 

personnel are directed to provide water spray cooling to tank cars, to prevent boiling liquid 

expanding vapor explosions from occurring. In tunnel fires, space restrictions may make it 

difficult or impossible to mount an effective emergency response, either to cool tank cars or 

extinguish the fire. This could result in a fire burning unchecked, having a longer duration, and 

possibly reaching higher temperatures, compared to a fire with essentially the same fuel supply 

occurring in an unobstructed (non-enclosed) environment. Based on these factors, fires 

occurring in tunnels have the potential of being more severe than fires occurring in non-tunnel 

environments. The only significant limiting factor in a tunnel fire, which would not affect a fire in 

an open environment, is the potential for limited ventilation in a tunnel (due to tunnel length or 

small degree of slope), which could greatly reduce the amount of oxygen available for 

combustion. This would tend to reduce the burn rate, which would reduce the intensity of the 

fire, and thus tend to produce lower temperatures, even for a longer fire duration.

3.2.2 A Review of Rail Transportation Accidents

As part of its investigation of the impact of the Baltimore tunnel fire on the transportation of SNF, 

NRC staff conducted a detailed survey of rail transportation accidents in the United States. The 

staff reviewed accident reports (particularly those of the National Transportation Safety Board 

[NTSB]), historical media accounts, and data from the Federal Railroad Administration (FRA) 

safety database, and from the Association of American Railroads (AAR). This review showed 

that severe rail fires, either in tunnels or open environments, are extremely infrequent events. 

The staff’s review revealed several facts about rail accidents in the United States in general, 

and those involving hazardous materials specifically. These facts, which are summarized 

below, aid in putting the Howard Street Tunnel fire into perspective.

• In nearly 34 billion kilometers (21 billion miles) of travel on American railroads between 

1975 and 2005, there have been 1700 reported incidents involving release of hazardous 

materials.

• Many of the 1700 incidents involved minor releases of non-flammable hazardous materials. 

None of the incidents reviewed involved the release of any radioactive material.

• Of the 1700 incidents, there were eight that involved a significant quantity of flammable 

material and that resulted in a long-duration fire. These incidents3 were as follows: 

1. Derailment of CSX freight train, Baltimore, Maryland, July 18, 2001 (the subject of this 

report)

2. Derailment of Union Pacific Freight train, Eunice, Louisiana, May 27, 2000 [NTSB report 

RAR-02-03; NTIS report PB2002-916303]

 2 2004 Emergency Response Guidebook, U.S. Department of Transportation, pages 115 and 128. 3 The reports on these incidents are available on the NTSB web site, www.ntsb.gov, under the link “Accident 

Reports,” or from the National Technical Information Service (NTIS) web site, www.ntis.gov.
3-5

3. Derailment of Wisconsin Central freight train, Weyauwega, Wisconsin, March 4, 19964

4. Derailment of BNSF freight train, Cajon Pass, California, February 1, 1996 [NTSB report 

RAR-96-05; NTIS report PB96-916305]

5. Derailment of CSX freight train, Akron, Ohio, February 26, 1989 [NTSB report HZM-90-

02; NTIS report PB90-917006]

6. Derailment of MT Rail freight train, Helena, Montana, February 2, 1989 [NTSB report 

RAR-89-05; NTIS report PB89-916305]

7. Derailment of CSX freight train, Miamisburg, Ohio, July 8, 1986 [NTSB report HZM-87-

01; NTIS report PB-87-917004]

8. Derailment of Illinois Gulf Central freight train, Livingston, Louisiana, 

September 28, 1982 [NTSB report RAR-83-05; NTIS report PB83-916305]

Of these eight accidents, only one (the Baltimore tunnel fire) occurred in a tunnel. Based on an 

examination of the NTSB accident reports on the seven accidents listed above that did not 

occur in a tunnel, the staff concluded that none of them could have provided a fully engulfing fire 

environment for a spent fuel package, had one been involved in the event. 

This conclusion is based on three mitigating factors present in the accidents examined above: 

the potential proximity of a hypothetical SNF transportation package to the fire that occurred, the 

available fuel for the fire, and the emergency response time for each accident. These factors 

are expanded upon below:

1. Proximity: Using diagrams of the rail car configurations in the seven accidents, 

as given in the NTSB reports, a rail car carrying a spent fuel package 

and its required buffer cars could not have been located close enough 

to any tank cars that ruptured in these accidents. An SNF package, 

had one been involved, would not have been positioned near enough 

to the burning flammable material in these accidents to be fully 

engulfed.

2. Fuel for the fire: The flammable material involved in a majority of the accidents were 

gases that resulted in localized pressure fires, so these accidents did 

not involve the pooling of flammable liquids. In those that did involve 

flammable liquids, pooling did not occur because of the nature of the 

track bed, which is elevated over porous media. 

3. Response time: The emergency response times were extremely rapid in these seven 

accidents (most were responded to within 1-2 hours), and response 

efforts included cooling the tank cars, effectively minimizing fire 

intensity and duration. 

 4 The NTSB did not issue a report on this accident. Information describing the accident is available in the public 

docket, National Transportation Safety Board Public Docket for Railroad Accident at Weyauwega, WI, March 4, 1996. 

Docket ID: 8867, Released August 18, 1997, Washington, D.C. This document is available on the website: 

http://www.postcrescent.com/specials/assets/APCweyauweatrain/default.htm.
3-6

The Howard Street rail tunnel derailment and fire is unique in that none of the mitigating factors 

noted above (for non-tunnel fires) were acting to significantly limit the severity or duration of the 

fire. However, the staff’s examination of the FRA database shows that the Howard Street 

Tunnel derailment and fire is the only severe rail tunnel fire involving hazardous materials 

shipments that has occurred in the nearly 21 billion rail miles of transportation that took place in 

the United States between 1975 and 2005. 

When this accident frequency is coupled with the expected number of shipments of radioactive 

material in the future, the risk of an accident of this type still remains low. In addition, several 

factors work to reduce the risk of this type of accident even further. These include: 

1. The intent of the U.S. Department of Energy (DOE) to ship the bulk of SNF and HLW to 

the Proposed Geological Repository for the Disposal of SNF and HLW at Yucca 

Mountain (Yucca Mountain) via dedicated rail5

; 

2. FRA consideration of enactment of regulations that would require the use of dedicated 

trains6 for the shipment of SNF and HLW; 

3. AAR enacting, at the recommendation of the NRC, a “no-pass” rule7 for single bore dualtrack rail tunnels. The rule specifies that trains carrying tank cars containing hazardous 

materials, such as flammable or combustible liquids, and trains carrying SNF or HLW 

may not pass one another within the same tunnel.

This investigation has shown that accidents involving hazardous materials and long-duration 

fires on railroads in general and in rail tunnels in particular occur with extremely low frequency. 

As discussed above, DOE, FRA, and AAR have taken steps to further preclude the possibility of 

such an accident involving SNF or HLW and other hazardous (flammable or combustible) 

materials in a rail tunnel. Consequently, the frequency of any rail accident involving an SNF or 

HLW shipment in conjunction with a long-duration fire in a rail tunnel essentially approaches 

zero.

3.3 SNF Transport Plans

Two DOE efforts involve planning for transport of radioactive material to interim and/or 

permanent storage. The first is the National Transportation Plan (DOE 2009) prepared by the 

Office of Civilian Radioactive Waste Management in preparation for shipment of radioactive 

materials to the proposed Yucca Mountain repository. A significant feature of this plan is the 

design of the train and the design of the rail car that will carry the SNF package. The design 

standard is described in AAR S-2043. This standard results in a transport vehicle that is 

capable of carrying the SNF package at normal speeds on commercial rail lines while providing 

reasonable assurance that the cask maintains secure linkage to the AAR S-2043 railcar. 

Elements of the train are mentioned in the section above, including the use of buffer cars, which 

in this case are ballasted, and use of a train dedicated for the SNF transport. A security escort 

car is attached to the rear of the train. Figure 3.2 shows a schematic of the proposed 

arrangement. The second, and more recent, activity, known as the Nuclear Fuel Storage and 

 5 Letter to Stakeholders from Paul M. Golan, Principal Deputy Director Office of Civilian Radioactive Waste 

Management, July 18, 2005.

6 This consideration is mandated pursuant to Section 5105(b) of the Hazardous Materials Transportation Uniform 

Safety Act of 1990, As Amended.

7 Circular No. OT-55-I (CPC-1174), American Association of Railroads, July 17, 2006.
3-7

Transportation Planning Project, addresses transfers of SNF from shutdown sites8

, i.e., shut 

down commercial nuclear power stations where the stored fuel in the independent spent fuel 

storage installation is one of the final vestiges of a decommissioned site (Maheras et al. 2014). 

The transport trains planned for this effort will match those described under the National 

Transportation Plan: “Cask-carrying railcars, buffer cars, and security cars will be required to 

meet AAR Standard S-2043.”

As described above, railway transport figures prominently in both plans, either directly from the 

site or after heavy-haul on roadway or barge to the nearest practical rail link; several elements 

of these plans offer enhancements to SNF rail transport safety.

Figure 3.2. Rolling Stock, Escort, and Buffer Car Schematic (Figure ‘E’ in DOE 2009)

 8 M. Bates, “Preparation for Transportation of SNF Stored at Commercial Nuclear Power Plants”, Presented June 24, 

2015 to Nuclear Waste Technical Review Board, Golden, Colorado.

4-1

4.0 STUDIES TO EVALUATE ADEQUACY OF

DESIGN REQUIREMENTS

As part of the process of establishing the regulatory basis for issuance of certificates for 

transportation of radioactive material under 10 CFR 71, the NRC has sponsored studies of the 

risks associated with the shipment of spent power reactor fuel by truck and rail. When these 

studies address risks associated with a spent fuel package in a fire, the analysis is performed 

with numerical models. NRC has also supported studies of component performance, in 

particular seals. 

Section 4.1 summarizes the steps followed in fire accident analyses described in this report. 

Section 4.2 briefly describes qualifications of models that have been used in these studies in 

terms of model validation and verification. A summary of current testing of seal performance at 

elevated temperatures is provided in Section 4.3. Section 4.4 is a brief description of the SNF 

packages used in the fire accident scenarios summarized in this report.

4.1 Approach to Analysis of Fire Accident Scenarios

The approach taken in analyses of fire accident scenarios is as follows:

1. Describe fire to extent possible with available photos, video, first responder reports, and 

post-fire documentation.

2. Supplement if possible with temperature estimates using post-fire materials examination.

3. Perform Computational Fluid Dynamics (CFD) analysis of the fire behavior, using boundary 

conditions consistent with observations in 1) and 2).

4. Define SNF accident scenario with plausible, most conservative package location for 

thermal response.

5. If structural damage is suggested by accident, define associated accident scenario with 

plausible, most conservative package location.

6. Perform transient thermal analysis for package in defined scenario, using hot NCT as the 

initial steady-state condition, and simulate the fire with boundary conditions based on 

combustion gas temperatures and velocities predicted by analyses in Step 3).

7. Perform structural analysis consistent with defined scenario; this may be required before or 

following the thermal analysis, or between successive thermal analyses (see [NUREG/CR7206 2015]).

8. Assess any impact to shielding.

9. Assess possibility of release of package radioactive contents based on seal temperatures, 

closure seal function (which may require structural analysis, again see [NUREG/CR-7206

2015]) and cladding temperatures.

10. Assess potential for cladding failure and rod rupture when estimating potential for release. 

Assume 100% spalling of surface Chalk River Unknown Deposit (CRUD) from fuel rods, for 

intact or failed fuel rods.
4-2

11. If peak clad temperatures approach or exceed short-term limit for accident conditions 

(570°C [1058°F]), perform best estimate calculation of cladding burst rupture based on initial 

pressurization and thermal transient, using an appropriate fuel rod material performance 

code.

12. Evaluate potential for release, based on containment integrity (e.g., seal performance), and 

estimate potential release if/as required.

4.2 Numerical Models

Analyses of the fire behavior, which was used to generate boundary conditions to define the fire 

scenarios, were performed with the Fire Dynamics Simulator (FDS) code (McGrattan 2001a). 

Thermal and structural models of SNF packages subjected to the fire conditions were 

developed for the ANSYS (ANSYS 2003) code and the COBRA-SFS (Michener et al. 1996) 

code. Independent validation efforts were not undertaken for the various codes used in the 

analyses, as this was beyond the scope of the fire analysis work. Instead, the validation of the 

codes, as documented in their base references, was relied upon to justify their use in these fire 

accident scenarios. However, the specific models of SNF packages developed using these

codes were verified by appropriate comparisons to reference cases, generally from the relevant

package Final Safety Analysis Report, or evaluations of sensitivity studies, using typical “good 

practices” standards (for example, see NUREG-2152 2013). 

4.2.1 Fire Dynamics Simulator

The validation of the FDS code is extensive and widely documented1 in the open literature. The 

most relevant validation work, for the purposes of the fire studies summarized in this report,

includes comparisons to results of tunnel fire tests with conditions similar to the tunnel fire

scenarios discussed in Section 5.0. The National Institute of Standards and Technology (NIST) 

developed fire models using FDS based on the geometry and test conditions from a series of 

tunnel fire experiments conducted by the Federal Highway Administration and Parsons 

Brinkerhoff, Inc. as part of the Memorial Tunnel Fire Ventilation Test Program (Bechtel/Parsons 

Brinkerhoff 1995). NIST modeled both a 6.83×107 Btu/hr (20 MW) and a 1.71×108 Btu/hr 

(50 MW) unventilated fire test from the Memorial Tunnel Test Program, and achieved results 

using FDS that were within 100°F (56°C) of the recorded data (McGrattan et al. 2001a, 2001b).

The fire conditions predicted with FDS for the various scenarios considered were verified to the 

extent possible using available information on fuel sources, geometry of the fire, and actual fire 

duration, based on reports and photographs from first responders at the scene. In some cases, 

additional information on temperatures reached in the fire was obtained from material sampling 

of structures engulfed in the fire.

 1 See http://firemodels.github.io/fds-smv/.
4-3

4.2.2 COBRA-SFS

COBRA-SFS was developed by Pacific Northwest National Laboratory for thermal-hydraulic 

analyses of multi-assembly spent fuel storage and transportation systems. The code uses a 

lumped-parameter finite-difference approach for predicting flow and temperature distributions in 

spent fuel storage systems and fuel assemblies under forced and natural circulation flow 

conditions. It is applicable to both steady-state and transient conditions in single-phase gascooled spent fuel packages with radiation, convection, and conduction heat transfer. The code 

has been validated in blind calculations using test data from spent fuel packages loaded with 

actual spent fuel assemblies, as well as electrically heated single-assembly tests (Creer et al. 

1987; Rector et al. 1986; Lombardo et al. 1986).

As the only thermal analysis code that has been systematically validated against essentially all 

of the available experimental data on spent fuel storage systems, particularly multi-assembly 

storage systems, results from models developed for COBRA-SFS are used as the standard of 

evaluation of models developed with other CFD codes. Verification of specific COBRA-SFS 

models developed for the fire analyses was obtained by comparison to specific cases from the 

safety analysis report (SAR), and cross-comparison with other CFD models.

4.2.3 ANSYS

Systematic validation of the ANSYS code against experimental data for spent fuel storage and 

transportation packages has not been published in the open literature. However, this code is 

widely used in the industry to model thermal and structural response of SNF storage and 

transportation packages, for design purposes, and licensing basis calculations. The models 

developed for specific packages evaluated in the fire scenarios discussed here were verified by 

comparison to specific cases documented in the relevant SAR for normal conditions of 

transport, and in some cases for the standard HAC fire. In addition, the results obtained with 

the ANSYS model were evaluated by comparison to results obtained with a COBRA-SFS model 

of the same or similar system. 

4.3 Seal Performance Testing

The NRC and NIST tested seals in thermal conditions simulating fire environments that exceed

the rated temperatures for the seals tested (NUREG/CR-7115 2015). Testing was conducted in 

three phases. 

The first phase of these tests evaluated the performance of one type of metallic seal and two 

different polymeric compound seals typically used in SNF transportation packages. The test 

fixture consisted of a small stainless steel cylindrical vessel fitted with a flange and lid closure 

for a single O-ring seal. The test vessel was pressurized at room temperature with helium to 

73.5 psia (5 bar) for the tests with metallic seals, and to 29.4 psia (2 bar) for the tests with 

polymeric seals. The fire was simulated using an electric furnace that could maintain a 

controlled thermal environment for a specified duration, which was varied in different tests from 

several hours to 24 hours, and in some cases up to 72 hours. (These tests were designed to 

simulate accident conditions. Typical seal tests for long-term normal operating conditions are 

performed for a minimum of 1000 hours.) Following the simulated fire exposure duration, the 

test vessel was allowed to return to room temperature within the electric furnace. 

A total of 15 tests were conducted in this study, including the initial shakedown test for which 

results were not recorded, due to instrumentation failure. Of the 14 tests for which 
4-4

measurements were recorded, 11 tests were with a metallic seal, 2 tests were with an ethylene

propylene (EPDM) seal, and one test was with a polytetrafluoroethylene (PTFE) seal. In terms 

of the applicability of this testing to the evaluation of the packages used in the fire scenarios 

described in this report (see Section 4.4), the two tests with EPDM seals are of significance 

since this is the seal material used in the GA-4 package for the lid closure, the gas sampling

port valve, and the drain valve. The Nuclear Assurance Corporation (NAC) legal-weight truck 

(LWT) uses Teflon (PTFE) seals for the drain and vent ports and a combination of metallic and 

Teflon seals for the bolted lid, and the HI-STORM and TN-68 both use metallic seals 

(NUREG/CR-6886 2009).

The majority of the metallic seal tests were performed at (or near) a maximum temperature of 

1472°F (800°C) and this temperature was held for 9 hours. The ability to maintain vessel 

pressure during these tests was mixed, with leakage observed in three of the six tests. No 

leakage was observed in two shorter duration2 tests at 1472°F (800°C). Also no leakage was 

observed in the single test at 1160°F (627°C), nor in the three 9-hour tests at 800°F (427°C).

The most severe exposure for EPDM seals in the testing was at 842°F (450°C). The seal 

material failed in this test within the first three hours of the simulated fire transient, but exhibited 

a much slower leak rate than would be expected for the test vessel with no seals at the test 

conditions. The second test with EPDM seals reached a much lower peak temperature, with

incremental heating from 302°F (150°C) to 572°F (300°C). The total duration of this test was 

more than 20 hours, but the seal held with no measurable leakage. 

The single test with the PTFE seal was limited to a maximum temperature of 572°F (300°C). 

The seal held for the duration of the 22 hour heated portion of this test, but did have leakage 

during the cooling phase. 

Subsequent testing in Phase II extended the polymeric O-ring seal materials tested to include 

butyl, Viton, and silicone. Additional tests were also completed with EPDM and PTFE seals. 

These tests used the same initial fill pressure as used for polymeric seals in Phase I, 29.4 psia 

(2 bar), but in this series the test vessel was held at 600°F (316°C) for 8 hours. Of the eighteen 

tests completed, only in one test with a silicone seal was there a loss of pressure that exceeded 

the measurement uncertainty. In the other tests pressure returned to the initial value after the 

test vessel returned to room temperature. While largely retaining their sealing function, the 

seals suffered significant damage in the process. The Viton seal tests displayed the unique 

behavior of a net internal pressure increase during the test, presumably due to off-gassing. 

Phase III testing used the same test vessel except that it was fitted with a flange and lid with a 

double O-ring seal configuration. In one group of tests, the inner seal was in all cases metallic,

and tests were conducted with or without an EPDM outer seal. A second group of tests used 

polymeric O-ring seals exclusively, the first set with EPDM O-rings in both seal locations and the 

second with butyl O-rings in both seal locations. A final group of tests used metallic seals for 

both the inner and outer seals. As in the Phase I metallic seal tests, the initial helium fill 

pressure was 5 bar at room temperature. In the first two EPDM-metallic tests, the test vessel 

was heated to 1472°F (800°C), held for 9 hours, and allowed to return to room temperature. 

The remaining tests used the same procedure, except that the vessel was heated to 1652°F 

(900°C). Results of tests using a metallic seal were again mixed, showing no leakage in the first 

group of tests that had an EPDM or blank outer seal, and showing some leakage in all of the 

 2 The initial shakedown test was run for 30 minutes and a second test was run for 4 hours.
4-5

final group of tests with metallic seals in both locations. Leakage was detected in all of the dual 

polymeric seal tests prior to the test temperature being reached.

Results of these seal tests demonstrate that seals used in SNF packages may have a shortterm performance envelope that far exceeds the conservative temperature limits indicated in the 

ratings for long-term performance provided by the seal manufacturer. While these results are 

encouraging from the standpoint of lower potential releases in the event of an accident, seal 

function at these elevated temperatures has not shown consistent performance; therefore for 

the purpose of safety analysis, when temperatures in the area of the seal exceed the rated 

values provided by the seal manufacturer, the seal must be assumed to have failed as part of 

the containment analysis.

4.4 SNF Packages Included in Case Studies

Detailed descriptions (including engineering drawings, technical specifications, and material 

data sheets) for the three spent fuel transportation package designs selected for these analyses 

are documented in proprietary versions of their respective SARs. This subsection presents a 

general overview of the SNF packages that have been evaluated in fire accident scenarios. 

Section 4.4.1 describes the TransNuclear TN-68 rail transportation package. Section 4.4.2

describes the HOLTEC HI-STAR 100 rail transportation package. The NAC LWT transportation 

package is described in Section 4.4.3 and General Atomics GA-4 LWT transportation package 

is described in Section 4.4.4. 

4.4.1 TransNuclear TN-68 SNF Transportation Package

The TN-68 spent fuel shipping package is designed to transport boiling water reactor (BWR)

spent fuel assemblies by rail. The package can be loaded with up to 68 BWR spent fuel 

assemblies, with a maximum total decay heat load of 72,334 Btu/hr (21.2 kW). The fuel 

assemblies are contained within a basket structure consisting of 68 stainless steel tubes with

aluminum and borated aluminum (or boron carbide/aluminum composite) neutron poison plates 

sandwiched between them. The containment boundary is provided by the package outer steel 

shell and lid seals. The general structure of the TN-68 package is illustrated in Figure 4.1 and 

Figure 4.2. Detailed information on the design can be found in the appropriate sections of the 

TN-68 SAR (NRC 2000).

The basket structure is supported by aluminum alloy support rails bolted to the inner carbon 

steel package shell, which also serves as the inner gamma shield. This inner steel shell is 

shrink-fitted within an outer carbon steel shell that serves as the outer gamma shield. The 

gamma shielding is surrounded by the neutron shielding, which consists of a ring of aluminum 

boxes filled with borated polyester resin. The outer shell of the package is carbon steel, as is 

the package base and inner steel shield plate. The package lid is also carbon steel with a steel 

inner top shield plate. During transport, the ends of the package are capped with impact limiters 

made of solid redwood covered with a thin layer of balsa wood and enclosed within stainless 

steel sheathing. The TN-68 package weighs approximately 260,400 lb (118,115 kg) when 

loaded for transport.
4-6

Figure 4.1. Cross-section of TN-68 Package (drawing 972-71-3 Rev. 4, “TN-68 

Packaging General Arrangement: Parts List and Details”)
4-7

Figure 4.2. Exterior View of TransNuclear TN-68 Spent Fuel Transportation Package 

with Impact Limiters Installed

4.4.2 HOLTEC HI-STAR 100 SNF Transportation Package

The design of the HOLTEC HI-STAR 100 SNF transportation package is similar to that of the 

TN-68 in that it consists of a heavy steel outer shell, base, and lid, with an internal basket 

structure designed to contain multiple SNF assemblies. In addition, the HI-STAR 100 design 

encloses the basket structure containing the spent fuel within a welded multi-purpose canister 

(MPC). This provides an inner containment barrier, in addition to the package outer shell and lid 

seals. The HI-STAR 100 can accommodate a variety of MPC configurations containing three 

different spent fuel support basket designs; one for up to 24 pressurized water reactor (PWR)

assemblies, another for up to 32 PWR assemblies, and one for up to 68 BWR assemblies. 

The MPC-24 configuration was selected for this evaluation, because it is the limiting 

configuration for this system. It has the highest operating temperature of the HI-STAR 100 

licensed fuel loading configurations, and therefore is likely to be the most adversely affected by 

exposure to the postulated severe fire scenario. This design has an integral fuel basket that 

accommodates 24 PWR spent fuel assemblies with a maximum total decay heat load of 

68,240 Btu/hr (20.0 kW). The MPC is loaded with SNF and welded shut, and then placed in the 

transportation package (also referred to as the overpack) for shipment. An exploded cut-away

diagram of the HI-STAR 100 package system (MPC and overpack) is shown in Figure 4.3. The 

package inner shell is stainless steel, and six layers of carbon steel plates comprise the gamma 

shield. The next layer is a polymeric neutron shield, strengthened by a network of carbon steel 

stiffening fins. The outer shell of the package is carbon steel, with a painted exterior surface. 
4-8

Figure 4.3. HOLTEC HI-STAR 100 Spent Fuel Package

Aluminum honeycomb impact limiters with stainless steel skin are installed on the ends of the 

package prior to shipping. Impact limiters protect the closure lid, MPC, fuel basket, and 

contents from damage in the event of a package drop accident. The impact limiters also 

provide thermal insulation to the lid and port cover components in the event of fire exposure. 

Figure 4.4 shows an illustration of this package secured to a railcar, with impact limiters 

installed. This package weighs approximately 277,300 lb (125,781 kg) when loaded for 

transport. Additional configuration details are provided in the HI-STAR 100 Package System 

SAR (NRC 2001a).
4-9

Figure 4.4. Spent Fuel Transportation Package on Railcar3

4.4.3 NAC LWT SNF Transportation Package

The NAC LWT is a small transportation package certified for transport on a standard tractortrailer truck, but can also be transported by rail. When shipped by rail, the NAC LWT is typically 

placed within an International Organization for Standardization (ISO) shipping container. It can 

also be placed within an ISO when shipped by truck. Figure 4.5 shows a NAC LWT package on 

a flat-bed trailer with a personnel barrier installed, but without an ISO container. Figure 4.6

shows an exterior view of the package within an ISO container on a flat-bed trailer. This 

package is designed to transport a variety of commercial and test reactor fuel types with widely 

varying maximum decay heat load specifications for the different fuels. For the purposes of this 

thermal analysis, the package was assumed to contain a single PWR SNF assembly with a 

maximum decay heat load of 8,530 Btu/hr (2.5 kW). This is the highest heat load the package

is rated for with any spent fuel it is designed to carry4

, and thus provides a conservative thermal 

load for the fire accident scenario. 

 3 Image courtesy of HOLTEC International. 4 As of Revision 34 of the SAR for this package; see (NRC 2001b).
4-10

The loaded package weighs approximately 52,000 lb (23,586 kg). The containment boundary 

provided by the stainless steel package consists of a bottom plate, outer shell, upper ring 

forging, and closure lid. The package has an additional outer stainless steel shell to protect the 

containment shell, and also to enclose the lead gamma shield. Neutron shielding is provided by 

a stainless steel neutron shield tank containing a mixture of borated water and ethylene glycol. 

An additional annular expansion tank for the mixture is provided, external to the shield tank. 

This component is strengthened internally by a network of stainless steel stiffeners. Aluminum 

honeycomb impact limiters covered with an aluminum skin are attached to each end of the 

package. Additional configuration details are provided in the SAR for this transport package

(NRC 2001b).

Figure 4.5. NAC LWT Transport Package (without ISO Container)
4-11

Figure 4.6. NAC LWT Transport Package (with ISO Container)

4.4.4 General Atomics GA-4 LWT SNF Transportation Package

This is an NRC-certified SNF transportation package that can carry a relatively large payload for 

an over-the-road transportation package, and therefore the potential consequences of package 

failure could be more severe than for packages with smaller payload capacities. The GA-4 

package is designed to transport up to four intact PWR spent fuel assemblies with a maximum 

decay heat load of 2105.4 Btu/hr (0.617 kW) per assembly, for a total package decay heat load 

of 8423 Btu/hr (2.468 kW). The payload capacity of the GA-4 is 6,648 lb. (3,015 kg), and the 

fully loaded package weighs approximately 55,000 lb (24,948 kg). 

Figure 4.7 shows an exploded view of the package, illustrating the main design features. The 

package containment boundary is provided by the following structures:

• stainless steel package body wall 

• stainless steel bottom plate 

• stainless steel package closure lid secured by Inconel fasteners 

• dual O-ring seals for the closure lid, gas sample port, and drain valve. 

The stainless steel package body encloses the gamma shield, which consists of an inner shell 

of depleted uranium. Neutron shielding is provided by a stainless steel neutron shield tank, 

external to the package body, which contains a water/propylene glycol mixture. Aluminum 

honeycomb impact limiters, completely enclosed in a thin stainless steel outer skin and inner 

housing, are attached to each end of the package. Configuration details, including design 

drawings, are provided in the SAR for this transport package (General Atomics 1998).
4-12

Figure 4.7. GA-4 Package: Exploded View (General Atomics 1998) 
5-1

5.0 ACCIDENT SCENARIOS INVOLVING SNF

PACKAGES IN SEVERE FIRES

This section describes the four NRC developed accident scenarios based on four historical 

severe fires. Using the wording of the recommendation in the NAS study (NAS 2008), these are 

all “very long-duration fire scenarios that bound expected real-world accident conditions.” One 

of the fires occurred in a rail tunnel. The other three involved trucking accidents, two of which 

occurred in roadway tunnels, and the third occurred in a stacked layer of freeway interchange 

ramps. 

A description of the actual fire is presented first, followed by a summary of analyses and postfire testing to establish conditions in the fire. The accident scenario defined for each case is 

then described, which incorporates bounding assumptions and places selected SNF 

transportation packages in the most adverse configuration within the fire. 

5.1 Baltimore Tunnel Fire

The first accident scenario is based on the railway fire that occurred in 2001 in the Howard 

Street Tunnel in Baltimore, Maryland. This accident is in some contexts referred to as the 

Baltimore tunnel fire. This section is a summary description from the detailed discussion of the 

fire accident in the final report (NUREG/CR-6886 2009) on the modeling study.

5.1.1 Description of the Baltimore Tunnel Fire

On July 18, 2001, a CSX freight train carrying hazardous (non-nuclear) materials derailed and 

caught fire while passing through the Howard Street railroad tunnel in downtown Baltimore, 

Maryland. The Howard Street Tunnel is a single-track railroad tunnel of concrete and refractory 

brick. Originally constructed in 1895, later additions extended it to its current length of 

1.65 mi (2.7 km). The tunnel has an average upward grade of only 0.8% from the west portal to 

the east portal, and at the time of the accident, the active ventilation system was not in 

operation. The tunnel is approximately 22 ft (6.7 m) high by 27 ft (8.2 m) wide in the vicinity of 

the accident (see Figure 5.1); however, these dimensions vary somewhat along the length of 

the tunnel. 

The freight train had a total of 60 cars pulled by three locomotives, and was carrying paper 

products and pulp board in boxcars, as well as hydrochloric acid, liquid tripropylene1, and other 

hazardous liquids in tank cars (McGrattan and Hammins 2003, Barabedian et al. 2003). As the 

train was passing through the tunnel, 11 of the 60 rail cars derailed. A tank car (Figure 5.2) 

containing approximately 28,600 gallons (108,263 liters) of liquid tripropylene had a 1.5-inch 

(3.81-cm) diameter hole punctured in it (Figure 5.3) by the car’s brake mechanism during the 

derailment.

Ignition of the liquid tripropylene led to the ensuing fire. The exact duration of the fire is not 

known with certainty. Based on NTSB interviews of emergency responders, it was determined 

that the most severe portion of the fire in the Howard Street Tunnel lasted approximately 

3 hours. Less severe fires burned in the tunnel for periods of time greater than 3 hours. 

Approximately 12 hours after the fire started, firefighters were able to visually confirm that the 

tripropylene tank car was no longer burning. 

 1 Tripropylene carries an NFPA hazards rating of 3 for flammability, which is the same as that of gasoline.
5-2

Figure 5.1. Dimensions of Howard Street Tunnel with Tank Car on Track

Figure 5.2. Liquid Tripropylene Tank Car
5-3

Figure 5.3. Puncture in Tank Car

Tripropylene, which is also called nonene, is a liquid hydrocarbon compound used for industrial 

processes. Table 5.1 lists the heat of combustion for tripropylene and a number of other 

hydrocarbon fuels that are commonly shipped by rail. Gasoline and jet fuel are also included in 

the table, but for comparison purposes only, as these fuels are rarely, if ever, transported by rail. 

Tripropylene has a heat of combustion comparable to that of gasoline and has a higher heat of 

combustion than that of jet fuel. When compared to other common hydrocarbon liquids, 

tripropylene falls near the high end of the range of values for heat of combustion for 

hydrocarbon liquids. The range of values shown in Table 5.1 for hydrocarbon fuels is relatively 

narrow, however, which indicates that when burned under the same conditions, these 

hydrocarbon liquids will generally have similar combustion characteristics. Therefore, while 

tripropylene was the specific fuel for the Baltimore tunnel fire, its combustion characteristics are 

generally representative of the behavior of other hydrocarbon fuels.
5-4

Table 5.1. Comparison of Various Hydrocarbon Liquids

Liquid Hydrocarbons Molecular Formula Heat of Combustiona

Btu/lb. (kJ/kg)

Propane C3H8 19,800 (46,000)

Butane C4H10 19,500 (45,400)

Isobutane C4H10 19,600 (45,600)

Pentane C5H12 19,300 (45,000)

Hexane C6H14 19,200 (44,700)

Heptane C7H16 19,200 (44,700)

Toluene C7H8 17,400 (40,500)

Octane C8H18 19,100 (44,400)

Nonane C9H20 19,000 (44,300)

Nonene (Tripropylene) C9H18 19,000 (44,300)

Decane C10H22 19,000 (44,300)

Undecane C11H24 19,000 (44,300)

Gasoline 

(mixture of heptanes, octanes, nonanes and 

decanes)

C8H15

b 19,100 (44,500)b

Jet Fuel, grade JP-1 18,500 (43,000)

Jet Fuel, grade JP-2 18,700 (43,500)

Jet Fuel, grade JP-3 18,700 (43,500)

Jet Fuel, grade JP-4 18,500 (43,000) a

Values derived from Perry, Chilton, and Kirkpatrick, Perry’s Chemical Engineer’s Handbook, 4th Edition, Table 3-202, 

Page 3-104. b

Typical values. Values will vary slightly depending on formulation. Derived from Ferguson and Kirkpatrick, Internal 

Combustion Engines, Applied Thermosciences, 2nd Edition, Page 316 and Table 10.8.

5.1.2 Analysis of the Baltimore Tunnel Fire

NIST developed a model (McGrattan and Hammins 2003) of the Baltimore tunnel fire using the 

FDS code (McGrattan et al. 2001a, 2001b)2 to assess the thermal environment within the tunnel 

during the fire. The NIST study was based on information developed by the NTSB investigation 

of the tunnel fire, including descriptions of the tunnel structural features, the damage to the rail 

cars, and the sequence of events in the accident. Using this information as the starting point for 

the calculations, the analysis was extended to include variation of significant unknown 

parameters to predict the range and distribution of temperatures that could have been sustained 

in the tunnel during and after the fire, and the duration of the fire. 

The FDS model developed by NIST included the full length of the Howard Street Tunnel with the 

rail cars represented as solid blocks elevated 3.3 ft (1 m) above the rail bed. The source of the 

fire was specified in the simulation as a pool of burning liquid tripropylene positioned below the 

 2 Formal publication of the FDS code documentation began in 2001 with Version 2. Continuing validation and 

development of the code led to Version 3 in 2002. Version 3 was used in the FDS analyses discussed in this report.
5-5

location of the hole that was punctured in the tripropylene tank car during the derailment. 

Parametric studies of the burning rate of the fire, based on the amount of available fuel, the air 

flow in the tunnel, the thermal conductivity of the bricks lining the tunnel, and sensitivity studies 

on the fuel pool area show that the Howard Street Tunnel fire was oxygen-limited. 

In the confined space of the tunnel, without forced ventilation, the heat release rate of the fire 

was constrained by the supply of oxygen rather than the supply of fuel. For a wide range of 

modeling assumptions, the overall heat release rate (or heat rate) for the fire was predicted to 

be no more than about 1.71×108 Btu/hr (50 MW). The highest peak temperatures predicted in 

these simulations were 1832-2012°F (1000-1100°C) in the flaming region of the fire. The 

calculation results showed that the hot gas layer above the rail cars within three to four rail car 

lengths of the fire was an average of 932°F (500°C). Peak temperatures on the tunnel surfaces 

were calculated to reach 1472°F (800°C) where flames directly impinged on the ceiling of the 

tunnel. The average tunnel ceiling temperature within a distance of three to four rail car lengths 

from the fire was calculated to be 752°F (400°C).

Staff from the Center for Nuclear Waste Regulatory Analysis, along with staff from NRC and 

NIST, examined the rail cars and tank car removed from the Howard Street Tunnel for evidence 

of high temperatures experienced by these components (Garabedian et al. 2003). Metallurgical 

analyses on the material samples collected indicated that material temperatures on the roof of 

the boxcar located approximately 66 ft (20 m) from the tank car were in the range of 1382-

1562°F (750-850°C) for approximately 4 hours. Material temperatures on other components of 

this boxcar were estimated to have reached values on the order of 1112°F (600°C). The 

estimates of time and temperature exposures support the detailed predictions of the NIST FDS 

model of the Howard Street Tunnel fire.

5.1.3 Accident Scenario for Baltimore Tunnel Fire

The Howard Street Tunnel fire was severe at least in terms of duration and it was very 

challenging in terms of accessibility for first responders. However the peak temperature at 20 m 

from the fire, the nearest possible location of an SNF package, had one been carried by the 

train involved in this derailment accident, was lower than that specified in the regulatory HAC 

fire. However, the conditions in this fire would have been much different if ventilation had been 

operating at the time of the fire. The fire would not have been oxygen-starved to the same 

extent it was with the ventilation system off.

In an effort to investigate possible scenarios that could produce long-duration, high temperature 

fires within this tunnel environment, and with an objective of identifying a conservative fire 

scenario, additional FDS simulations were performed using the model of the Howard Street 

Tunnel. In these simulations, the tunnel was assumed ventilated in a manner that allowed the 

fire to be fully oxygenated, and the fire was assumed to burn until the entire inventory of fuel in 

the tank car was consumed by combustion. This was accomplished in the model with additional 

ventilation inlets in the tunnel walls, rather than explicitly modeling the Howard Street Tunnel 

ventilation system. The area of the pool of fuel was assumed to correspond to the footprint of 

the tank car and the leak rate from the tank car was matched to the burn rate in order to 

determine the hottest and longest-lasting conditions for a fire scenario.

The resulting scenario was a fire lasting 6.7 hours with peak temperatures of 2084°F (1140°C) 

in the flame region, and 1958°F (1070°C) at 66 ft (20 m) downstream of the fire. Peak ceiling 

temperatures at that same downstream location were above 1832°F (1000°C) and were 

predicted to last from about 3 hours until the end of the fire. The heat rate for the fire in this 
5-6

scenario is approximately 1.71×109 Btu/hr (500 MW), which is an order of magnitude higher 

than the heat rate predicted for the fire when modeled with realistic boundary conditions. 

The accident scenario assumes that an SNF transport package is located at the shortest 

possible distance from the tank car carrying liquid tripropylene. With the DOT required “buffer 

car” between them this distance corresponds to the 66 ft (20 m) location described in the 

previous section. In the thermal response analyses (Section 6.1), the package is subject to the 

local temperature and gas velocity history from the FDS fire simulation at that location. The

peak gas temperature is shown in Figure 5.4, the peak tunnel surface temperature is shown in 

Figure 5.5 and the peak horizontal velocity is shown in Figure 5.6.

Figure 5.4. Peak Transient Ambient Air Temperatures in FDS Simulation of Baltimore 

Tunnel Fire Accident Scenario (Smoothed Values, NIST 20-m Data)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Elapsed Time (hours)

Temperature (°F)

Top Air Temperature

Side Air Temperature

Bottom Air Temperature

End of Fire

End of NIST 20m Transient

Fire Duration Post-Fire Duration (NIST Data) 
5-7

Figure 5.5. Peak Transient Tunnel Surface Temperatures for Floor, Walls, and Ceiling

in FDS Simulation of Baltimore Tunnel Fire Accident Scenario (Smoothed 

Values, NIST 20-m Data)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Elapsed Time (hours)

Temperature (°F)

Ceiling Temperature

Wall Temperature

Floor Temperature

End of Fire

End of NIST 20m Transient

Fire Duration Post-Fire Duration (NIST Data) 
5-8

Figure 5.6. Peak Transient Horizontal Velocities near Package Surface in FDS 

Simulation of Baltimore Tunnel Fire Accident Scenario (Smoothed Values, 

NIST 20-m Data)

Three different commercial transportation packages were evaluated in this study: the 

TransNuclear TN-68, the HOLTEC HI-STAR 100 and the NAC LWT. Of these, the TN-68 and 

HI-STAR 100 are large capacity transport packages designed for rail transport and the NAC 

LWT is a single-assembly capacity package that is licensed for use on rail and roadways. 

5.2 Caldecott Tunnel Fire

The second accident scenario is based on a roadway tunnel fire, which occurred in the 

Caldecott Tunnel near Oakland California in 1982. This is a summary description from the 

original report on the thermal evaluation of the potential effect of this fire on an SNF package 

(NUREG/CR-6894 2007).

5.2.1 Description of the Caldecott Tunnel Fire

Shortly after midnight on April 7, 1982 in Bore No. 3 of the Caldecott Tunnel on State Route 24 

near Oakland, California, an accident occurred involving a tank truck and trailer carrying 

8,800 gal. (33,310 liters) of gasoline (NTSB/HAR-83/01 1983). This tunnel bore is 3,371 ft 

(1027 m) long, with a two-lane roadway 28 ft (8.5 m) wide. Traffic is one-way from east to west, 

and the roadway has a 4% downgrade. Figure 5.7 shows a photograph3 of the west portal of 

the tunnel; Bore No. 3 is the opening on the far left. 

 3 From the Metropolitan Transportation Commission (MTC) newsletter, Transactions OnLine, June/July 2000 issue, 

http://www.mtc.ca.gov/news/transactions/ta06-0700/tunnel.htm. The MTC is the transportation planning, 

coordinating, and financing agency for the nine-county San Francisco Bay Area.

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Elapsed Time (hours)

Velocity (ft/sec)

Top Velocity (ft/sec)

Side Velocity (ft/sec)

Bottom Velocity (ft/sec)

End of Fire

End of NIST 20m Transient

Fire Duration Post-Fire Duration (NIST Data) 
5-9

In the accident, the tank trailer overturned and the entire vehicle (tanker and trailer) came to rest 

approximately 1650 ft (503 m) from the west portal of the tunnel. Gasoline spilled onto the 

roadway from the damaged tank trailer and caught fire. Within four minutes of the accident, 

heavy black smoke began pouring out the east portal of the tunnel. The tank truck, trailer, and 

five other vehicles in the tunnel were completely destroyed by the fire, seven persons were 

killed, and the tunnel incurred major damage.

Figure 5.7. West Portal of Caldecott Tunnel

A diagram of a typical cross-section of Bore No. 3 of the tunnel is shown in Figure 5.8. The 

tunnel can be actively ventilated when conditions warrant, with a total capacity of 1.5 million 

cubic feet per minute through ducting above the tunnel ceiling. However, the ventilation system 

was not operating at the time of the accident.
5-10

Figure 5.8. Cross-section Diagram of Bore No. 3 of Caldecott Tunnel

The overall duration of the fire is estimated at approximately 2.7 hours, but based on NTSB 

evaluations of the fire debris and interviews with emergency response personnel, the intensely 

hot gasoline-fueled portion of the fire is estimated to have lasted about 40 minutes. 

5.2.2 Analysis of the Caldecott Tunnel Fire

NIST developed a model of the Caldecott Tunnel with the FDS code for the section of the tunnel

that experienced the most severe effects of the fire (McGrattan 2005). In the model, the fire 

was located in the region between 1673-1706 ft (510-520 m) from the west portal, spanning a 

length nominally equivalent to the length of the tanker truck and trailer. The FDS model 

included 50 m of the tunnel upstream of the fire (toward the west portal of the tunnel) and 180 m 

downstream (toward the east tunnel entrance). Based on boundary conditions, including 

information on the available fuel and air sources, the FDS code was used to calculate the 

energy release from the combustion process, the resulting flow of air and hot combustion gases, 

and local air and surface temperatures throughout the tunnel. The FDS calculation simulated 

only the gasoline fire, neglecting any contribution to thermal energy release due to the burning 

vehicles since these were small and widely spaced apart.

The simulation calculates the rise in tunnel surface temperatures and gas velocities (air and 

combustion product) at different elevations in the tunnel and axial position following the start of 
5-11

the fire. Peak magnitudes occur at the ceiling and as shown in Figure 5.9 (temperature) and 

5.10 (velocity). Peak values in both quantities are essentially reached after only 10 minutes into 

the fire (temperatures within 100°C of the 935°C peak, velocity within 1 m/s of the 9.2 m/s peak) 

and these are maintained until the end of the gasoline-fueled fire at 40 minutes. The peak 

values in temperature and gas velocity occur about 80 m downstream of the fire (toward the 

tunnel entrance). Wall temperatures at mid-line are approximately 100°C below the values at 

the ceiling, and floor temperatures are approximately 100°C below the mid-line values. The 

mid-line and floor peak values occur 40 m further downstream than at the ceiling. Air velocities 

at the mid-line are much higher than near the ceiling or near the floor, reaching a peak of 

18 m/s, again at 40 m downstream of the peak at the ceiling. Peak velocity near the floor is 

lowest at 7.5 m/s.

Figure 5.9. Evolution of Ceiling Centerline Temperatures in FDS Simulation of 

Caldecott Tunnel Fire

0

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300

400

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600

700

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900

1000

460 480 500 520 540 560 580 600 620 640 660 680 700

Location in tunnel (meters, relative to west portal)

Temperature (°C)

ceiling T at 0 minutes

ceiling T at 1 minute

ceiling T at 2 minutes

ceiling T at 3 minutes

ceiling T at 5 minutes

ceiling T at 10 minutes

ceiling T at 15 minutes

ceiling T at 20 minutes

ceiling T at 25 minutes

ceiling T at 30 minutes

ceiling T at 39 minutes

location 

of fire

location of highest

tunnel ceiling temperature
5-12

Figure 5.10. Evolution of Gas Velocity Profile near Ceiling Centerline in FDS Simulation 

of Caldecott Tunnel Fire

5.2.3 Accident Scenario for Caldecott Tunnel Fire

The “hottest” overall location for a hypothetical accident scenario involving an SNF package was 

chosen to be 100 m downstream of the fire, mid-way between the location of peak temperature 

at the ceiling and the location of peak temperatures for the mid-line and floor. The surface and 

air temperatures predicted by the FDS model at that hottest location are shown in Figure 5.11

and Figure 5.12. Air velocities at that location are shown in Figure 5.13. 

The accident scenario assumes that an SNF transport package is located at the hottest location 

defined above. In the thermal response analysis, the package is subject to the local 

temperature and gas velocity history from the FDS fire simulation. In this analysis the NAC 

LWT transportation package is used to represent the response of a typical SNF package 

licensed for use on roadways (for a brief description of the NAC LWT, see Section 4.4.3).

0

1

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3

4

5

6

7

8

9

10

460 480 500 520 540 560 580 600 620 640 660 680 700

Location in tunnel (meters, relative to west portal)

Air velocity (m/sec)

upper air V at 1 minute

upper air V at 2 minutes

upper air V at 3 minutes

upper air V at 5 minutes

upper air V at 10 minutes

upper air V at 15 minutes

upper air V at 20 minutes

upper air V at 25 minutes

upper air V at 30 minutes

upper air V at 32.5 minutes

location 

of fire

location of highest tunnel 

upper air temperature
5-13

Figure 5.11. Peak Surface Temperatures in 3-hour FDS Simulation of Caldecott Tunnel 

Fire

Figure 5.12. Peak Gas Temperatures in 3-hour FDS Simulation of Caldecott Tunnel Fire

0

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1600

1700

1800

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00

Elapsed Time (hours)

Temperature (°F)

peak ceiling T

peak wall T

peak floor T

0

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0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00

Elapsed Time (hours)

Temperature (°F)

peak upper air T

peak middle air T

peak lower air T
5-14

Figure 5.13. Peak Gas Velocities in 3-hour FDS Simulation of Caldecott Tunnel Fire

5.3 MacArthur Maze Fire

This is a summary description from the original report on the thermal evaluation of the potential 

effect of this fire on an SNF package (NUREG/CR-7206, 2016). While not strictly a “tunnel” fire, 

the 2007 fire in the MacArthur Maze interchange provided some of the confinement 

characteristics of a tunnel fire without the constraint of tunnel walls to restrict the flow of air to 

the fire. Therefore, it was well oxygenated throughout the timeframe of active burning of the fuel 

source, producing high fire temperatures for the full duration of the fire, and in addition, added 

the unique effect of the collapse of an elevated roadway onto the wreckage and fire below. The 

fire peak temperatures and the relatively long fire duration in this case make it a potentially

challenging test for any SNF transport package postulated as exposed to such conditions. An 

additional complication would be the impaired cooling after the fire, and possible structural 

damage to the package, if it is assumed that the collapsed overhead roadway span fell onto the 

SNF package. Although the likelihood of an SNF transport being involved in an accident, with 

such a large fuel source and in such an unusual location, is very small, this third study case 

presents the “worst case scenario” among the four studies.

5.3.1 Description of the MacArthur Maze Fire

On April 29, 2007 at approximately 3:37 a.m., a tanker truck and trailer carrying 8,600 gallons 

(32,554 liters) of gasoline overturned and caught fire on the Interstate 880 (I-880) connector of 

the MacArthur Maze interchange located in Oakland, California. The intense heat from the fire 

weakened the steel girders of the Interstate 580 (I-580) roadway above, collapsing two adjacent 

spans (approximately 156 feet [47.55 m]) of the elevated roadway onto the section of freeway 

below. A surveillance camera from the monitoring system of the East Bay Municipal Utility 

0

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4

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8

10

12

14

16

18

20

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00

Elapsed Time (hours)

Velocity (m/sec)

upper air velocity

middle air velocity

lower air velocity
5-15

District Wastewater Treatment Plant adjacent to the roadway captured a video of almost the 

entire fire duration. This video shows the first I-580 roadway span beginning to sag by about 

10 minutes into the fire and collapsing completely at approximately 17 minutes. The video also 

shows one end of a second span of the I-580 roadway descending slowly to the lower (I-880) 

roadway, beginning at about 17 minutes and reaching its final (partially collapsed) configuration 

by about 37 minutes. The video shows that the collapse of the second span greatly reduced the 

size of the fire, but it continued to burn intensely until about 102 minutes. At that point, it began 

to noticeably decrease in brightness, diminishing to a small glowing spot by approximately 

108 minutes after the start of the fire. Figure 5.14 shows a post-fire aerial view of the collapsed 

spans, extracted from the California Highway Patrol Multi-Discipline Accident Investigation 

Team (MAIT) report (CHP 2007a).

Figure 5.14. Roadway Configuration after the MacArthur Maze Fire (photo from MAIT 

Report, CHP 2007a)

Part of the NRC analysis of this event included an assessment of the fire exposure 

temperatures of the upper roadway girders and parts of the remnants of the tanker truck (NRC 

2008). Based on analysis of temperature-dependent physical changes in the materials 

examined, the maximum steel temperatures were estimated to be in the range 1,796-1,868°F 

(980-1,020°C). These results indicate that material temperatures were generally below 1,832°F 

(1,000°C), and varied significantly with location in the fire. For example, there were unmelted 

segments of the tanker’s aluminum tank, and only partial melting of at least one of the truck’s 

aluminum wheels.
5-16

The material evaluations also suggest that the steel girders experienced maximum 

temperatures in the range of 1,472-1652°F (800-900°C) at locations deep within the interior of 

the fire. While well below the melting point of steel, exposure to these temperatures would 

significantly reduce the strength of the load-bearing girders. The yield strength of the A36 steel 

at the estimated maximum temperatures experienced during the fire is less than 20% of its 

normal room temperature value. With such a reduction in strength, the girders could not 

support the overhead spans.

5.3.2 Analysis of MacArthur Maze Fire

Numerical simulations of the pre-collapse fire were performed with the NIST FDS code. These 

simulations were used to characterize the fire, consistent with the video record and post-fire 

examination, to provide a basis for fire temperature and distribution to be used as boundary 

conditions for SNF package response models. Estimates were based on burn rate for pools 

formed by realistic fuel spills on concrete. The area of the fire was estimated from the video 

images and extensive regions of spalled concrete on the I-880 roadway, as shown in 

Figure 5.15. Modeling results supported characterizing the pre-collapse fire as an “open pool

fire with uniform flame temperature of 2012°F (1100°C)” over the period of the first 17 minutes 

of the fire. The fire directly under the fallen span was essentially extinguished by the blanketing 

of the fire in that region of the lower roadway. The fire continued to burn in the region beneath 

the adjacent, still supported span.

During the next 20 minutes, the second span of the upper (I-580) span slowly collapsed onto the 

lower (I-880) roadway, effectively extinguishing a large portion of the fire. Figure 5.15 illustrates 

the maximum possible size of the post-collapse fire, compared to the estimated maximum size 

of the pre-collapse fire. For the purpose of defining the thermal environment of the fire during 

this 20-minute transition phase, the fire temperature is conservatively assumed to remain at 

2012°F (1100°C), consistent with the conditions predicted with FDS for the large, pre-collapse 

pool fire. The post-collapse fire (out to 108 minutes total time) was modeled using this reduced 

area and a conservatively bounding flame temperature of 1652°F (900°C). A further level of 

conservatism was to treat this as a fully engulfing fire, even though its actual size is such that it 

could only partially engulfing an object as large as an SNF over-the-road transportation 

package.
5-17

Figure 5.15. Estimated Fire Pool for Pre- and Post-collapse Portion of the MacArthur 

Maze Fire

5.3.3 Accident Scenario for MacArthur Maze Fire

There are several different aspects of the MacArthur Maze fire that would expose an SNF 

transportation package to conditions more severe than the HAC fire specified in 10 CFR 71:

1. exposure of the package to a large fully engulfing fire that is more severe than the HAC fire,

prior to the collapse of the overhead I-580 roadway span between Bent 19 and Bent 20, at a

much higher engulfing flame temperature and conservatively represented with a slightly

longer duration (1100°C for 37 minutes, compared to 800°C for 30 minutes)

2. subsequent exposure of the package to the relatively long duration of the fire following the 

collapse of the overhead spans, which is also at a higher engulfing flame temperature

(900°C) and significantly longer duration (71 minutes) than the HAC fire

3. physical impact of a free falling overhead span on the package

4. post-fire cooldown with the package assumed to be covered by the concrete “blanket” of a 

collapsed overhead span.
5-18

The order of events for an SNF package in the MacArthur Maze fire scenario is exposure to fire, 

followed by a severe impact while still within the fire, and consequently with outer components 

of the package at high temperature. Because strengths of package materials are adversely 

affected by fire temperatures, the package might be more vulnerable to damage in this 

sequence of events.

To conservatively bound the worst that the MacArthur Maze fire could do to the SNF package, 

the scenario selected for analysis evaluated the most adverse thermal conditions and the most 

adverse structural configuration. The package was assumed positioned in the most adverse 

location for the different portions of the thermal analyses and the structural analyses, without 

realistic constraints on how the package could possibly relocate from one place to another 

during the fire scenario. For the thermal analysis, the package is assumed to be in the following 

locations:

• The package is on the lower I-880 roadway, fully engulfed in fire for 37 minutes, exposed to 

a flame temperature of 2012°F (1100°C).

• After 37 minutes, the package is still on the lower I-880 roadway, fully engulfed in fire, but 

the flame temperature is assumed to drop to 1652°F (900°C) for the remaining 71 minutes 

of the smaller post-collapse fire, resulting in a total fire exposure duration of 108 minutes.

• After 108 minutes of fire exposure, the package is still on the lower I-880 roadway, but is 

enclosed in a concrete “tunnel” simulating the collapsed roadway, which is cooled only by

natural convection from the exposed concrete surfaces of the upper and lower roadways.

A realistic location for the package to receive the maximum impact force from the free falling

overhead span would be near the edge of the large pool fire, or possibly outside the fire pool 

entirely. That is, a location that would result in maximum impact loading and post-fire blanketing 

by the fallen overhead roadway would be a location likely to receive minimum fire exposure. 

Conversely, if the package were positioned to receive maximum fire exposure (i.e., fully 

engulfed for both the pre-collapse and post-collapse fire conditions) it would have to be located 

near the middle of the area encompassed by the smaller post-collapse fire pool (see 

Figure 5.15), where it could not be struck at all by either of the two collapsed spans.

As a bounding assumption, the peak temperatures predicted in the thermal analysis for the fully 

engulfing 2012°F (1100°C) fire conditions (see Section 5.3.2 above) were imposed on the 

package in the structural analysis. The package was positioned at a location where it would 

receive the maximum force of impact from the collapse of the I-580 overhead span between 

Bent 19 and Bent 20.

The “package” selected for this scenario was the General Atomics GA-4 LWT (see 

Section 4.4.4), mainly because it can carry a relatively large payload for an over-the-road 

transportation package, consisting of up to four intact PWR spent fuel assemblies, and therefore 

the potential consequences of package failure could be more severe than packages with 

smaller payload capabilities. 
5-19

5.4 Newhall Pass Fire

This is a summary description from the original report on the thermal evaluation of the potential 

effect of this fire on an SNF package (NUREG/CR-7207 2016). This final accident scenario is 

based on the 2007 roadway fire in the freeway interchange tunnel referred to as the Newhall 

Pass, in Los Angeles County, California. The Newhall Pass accident was unique among the 

fires described in this report, in that it was not a pool fire surrounding a fuel transport vehicle. It 

was a chain reaction accident where most of the trucks involved were trapped inside this 

relatively short underpass tunnel. The trucks carried a variety of cargo, none of which was 

liquid fuel, except for the diesel fuel in their on-board tanks. The fire started in the pile-up of 

trucks near the tunnel exit, and was carried back through the tunnel from vehicle to vehicle, 

eventually engulfing all of the tractor-trailer rigs trapped within the tunnel. Within the tunnel, this 

was a long-duration and rapidly moving hot-spot fire. 

5.4.1 Description of the Newhall Pass Fire

On October 12, 2007 at approximately 11:40 p.m. (PDT), a chain reaction traffic collision and 

fire involving 33 commercial tractor-trailer rigs and one passenger vehicle occurred on a section 

of the southbound Interstate 5 truck route known as the Newhall Pass Tunnel, which passes 

under the main north-south lanes of Interstate 5. Figure 5.16 shows an aerial view of the 

roadway configuration, with the tunnel location marked by a red oval. 

The accident began when a tractor-trailer rig went out of control after exiting the tunnel and 

collided with the concrete median barrier, eventually coming to rest blocking both southbound 

lanes. The resulting pile-up of on-coming vehicles was reconstructed in the California Highway 

Patrol (CHP) MAIT report (CHP 2007b) as 13 separate collision sequences consisting of a total 

of 51 distinct impacts, with 24 of the 33 tractor-trailer rigs trapped within the Newhall Pass 

Tunnel. A fire started within the close pile-up of vehicles near the tunnel exit and spread rapidly 

from vehicle to vehicle, eventually filling the entire tunnel.
5-20

Figure 5.16. Aerial View of Roadway Configuration Showing Location of Newhall Pass 

Tunnel (image extracted from the CHP MAIT report [CHP 2007b]) 

Based on the photographic evidence and the timeline in the MAIT report (CHP 2007b), the 

active, intense fire that destroyed the trucks and their cargoes could have lasted no more than 

about 5 hours. During this time, fire fully engulfed each of the 24 tractor-trailer rigs within the 

tunnel, consuming all or most of their respective cargoes, and destroying the vehicles down to 

their steel frames and engine blocks. Nearly all of the sheet aluminum on the trailer boxes 

completely vanished, primarily by oxidization rather than by melting. Other more substantial 

aluminum alloy components showed evidence of local melting. 

In an assessment of the fire exposure temperatures within the tunnel (NUREG/CR-7101 2011), 

melted aluminum samples indicated that temperatures reached at least 1040°F (560°C) at some 

locations. Studies of hardness changes in graded bolts recovered from destroyed vehicles 

within the tunnel indicate that these components reached temperatures no higher than about 

1382°F (750°C). A single sample of brass material indicated a local temperature of at least 

1620°F (880°C) near the middle of the tunnel during the fire. Evaluation of the severe scaling of 

the carbon steel vehicle frames indicates that these components were exposed to temperatures 

exceeding 900°F (482°C).
5-21

5.4.2 Analysis of the Newhall Pass Fire

The information on the Newhall Pass fire presented by photographs taken during the fire and 

analysis of materials afterward was insufficient to provide a complete picture of the temperature 

history at various positions in the tunnel during this accident. Therefore FDS was again used to

model the Newhall Pass fire and develop boundary conditions for subsequent analysis of the 

effect of the fire on an SNF package.

In tanker truck and railway tank car fires, the approach to modeling centers on the pool fire. In 

the Newhall Pass fire, the source of combustibles was more dispersed and less easily identified. 

Detailed information on vehicle cargoes was incomplete, but the majority of the trucks involved 

in the fire were carrying fresh produce of one type or another (apples, oranges, lettuce, 

tomatoes, melons). One truck was carrying a load of sugar, another a load of coffee, another 

contained frozen baked goods, yet another carried general freight (most of which was not 

combustible). Several of the trucks were running empty. Other than the sugar and the coffee, 

the cargoes by themselves did not present any high-energy fuel sources. This suggests that 

except for the diesel in their fuel tanks (conservatively estimated as 200 gallons), the fuel load

for the fire on any given vehicle was much smaller than the fuel load available in any of the 

other fires evaluated in this study of severe real-world fires. 

For the analysis with FDS, the fuel load for the fires on the individual vehicle within the tunnel 

was established by creating a fuel budget for each vehicle, based on the assumed diesel fuel, 

typical combustible mass of the vehicle itself, and the combustible mass of a “typical” cargo. A 

range of burn rates and fire spread rates were postulated, based on available information on the 

fire timeline and a matrix of cases was defined to bound the range of possibilities, from short, 

intense fires on each vehicle, to the longest possible fire durations on each vehicle. Simulation 

results using these inputs were compared to overall fire duration and temperatures estimated 

from post-fire material examination. All of these cases were evaluated in the thermal analysis, 

to determine the bounding fire scenario, in terms of the potential effect on an SNF package, had 

one been involved in this fire.

5.4.3 Accident Scenario for Newhall Pass Fire

There are two aspects of the Newhall Pass fire that could expose an SNF package to conditions 

more severe than the hypothetical accident conditions specified in 10 CFR 71. The first is that a 

package located on any one of the vehicles in the tunnel could potentially be exposed to a fully 

engulfing fire with a temperature and duration that exceeds the HAC fire. (This requires 

assuming that an individual vehicle fire could engulf something as large as an SNF package, 

presumably on a nearby vehicle. How this could occur in reality is difficult to imagine, but 

assuming a fully engulfing fire is bounding, conservative, and a convenient simplification of the 

fire boundary conditions.) Second, the overall duration of the fire within the tunnel means that 

the package would be subjected to a period of pre-heating at ambient temperatures above the 

design basis for the package (typically 100°F [38°C]) prior to being engulfed in fire.

From the FDS analysis it was clear that the SNF package would experience the highest 

temperatures in the middle of the tunnel. Those results also showed that the package would 

experience the longest time above design-basis ambient if it was located a short distance inside 

the tunnel entrance. It was not obvious which of these would present the worst case for the 

package, so they were both considered in a matrix of package response analyses. This matrix 

was developed by considering bounding variations in the fire spread rate and the local vehicle 

fire burn time, to encompass the known parameters of the fire scenario. Table 5.2 summarizes 
5-22

these cases4

. In all cases, the total calculated fire duration is bounded by the uncertainty in the 

timeline of the fire. The period of intense, fully engulfing fires within the tunnel is known to have 

been somewhat longer than 2 hours, but less than 5 hours. Table 5.2 also summarizes two 

sensitivity cases evaluated, to conservatively bound the full range of possible fire behavior. 

NIST-05 evaluated the effect of the concrete spalling model in FDS on predicted fire 

temperatures. Case NIST-06 represented a bounding estimate of the actual fuel load for each 

vehicle, based on available information on the cargo of the various vehicles. This case was 

developed to verify that the assumed typical fuel load for all vehicles (including the empty ones) 

produced conservative estimates of the possible range of fire temperatures.

Table 5.2. FDS Cases Modeling Newhall Pass Tunnel Fire

Case Fuel Load Burn Rate Fire Spread Rate

NIST 01

typical fuel budget for each modeled vehicle 1.36 kg/s

0.01 m/s (slow)

NIST 02 0.015 m/s (moderate)

NIST 03 0.022 m/s (fast)

NIST 04 typical fuel budget for each modeled vehicle, but 

with burn rate doubled 2.72 kg/s 0.01 m/s (slow)

NIST 05 same as NIST 01 – sensitivity study on concrete spalling model in FDS

NIST 06

fuel load based on actual cargo (if known), 

typical cargo (if not known); no cargo for empty 

vehicles 

1.36 kg/s 0.01 m/s (slow)

The local vehicle fire durations and peak temperatures for these ten cases are shown in 

Table 5.3. The boundary temperatures for each case were varied to represent the pre-heat or 

cooldown for each location, as shown for one of the cases in Figure 5.17.

Table 5.3. Peak Fire Boundary Temperatures at “Hottest Fire” and “Longest Fire”

Locations

Case

Hottest Fire Location Longest Fire Location

Time of 

Peak (hr)

Local Fire 

Duration 

(minutes)

Peak Fire 

Temperature

Time of 

Peak (hr)

Local Fire 

Duration 

(minutes)

Peak Fire 

Temperature

NIST-01 2.84 ~60 1721°F

(938°C) 4.29 ~60 1579°F(859°C)

NIST-02 1.94 ~60 1706°F

(930°C) 2.39 ~60 1648°F(898°C)

NIST-03 1.47 ~60 1668°F

(909°C) 1.70 ~60 1570°F(854°C)

NIST-04 2.33 ~33 1991°F

(1088°C) 4.54 ~33 1736°F(947°C)

NIST-06 3.46 ~68 1861°F

(1016°C) 3.91 ~26 1646°F(897°C)

 4 A summary of these cases is presented here. For details, see Section 3.3 of NUREG/CR-7207.
5-23

Figure 5.17. Boundary Temperatures for Thermal Analysis of SNF Package in Newhall 

Pass Fire Scenario at “Most Adverse” Vehicle Locations for Case NIST-01

The General Atomics GA-4 LWT package was again selected for this investigation (refer to 

Section 4.4.4 for a brief description of this package). As in the MacArthur Maze accident 

scenario, the package was assumed to contain four WE 14x14 PWR spent nuclear fuel 

assemblies at the maximum permitted decay heat load for the package. This is the limiting 

design-basis configuration for thermal analysis of the package. 

0

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0 1 2 3 4 5 6

Elapsed Time (hours)

Temperature (°F)

NIST 01, hottest fire (Rig 23)

NIST 01 -- boundary temperature for hottest fire

NIST 01, longest fire (Rig 31)

NIST 01 -- boundary temperature for longest fire

6-1

6.0 ANALYSES OF FIRE ACCIDENT SCENARIOS

This section presents only a brief description of the method and details of the analyses for the 

fire and accident scenarios. The original references should be consulted for complete details. 

The Baltimore tunnel fire, Caldecott Tunnel fire and the Newhall Pass Tunnel fire scenarios only

required a thermal analysis. The MacArthur Maze fire also required some structural modeling, 

in addition to the thermal analyses, in order to predict potential consequences of the accident 

scenario.

6.1 Analysis of Baltimore Tunnel Fire Accident Scenario

Models of the three SNF packages were constructed in parallel with two codes: COBRA-SFS 

(TN-68) and ANSYS (HI-STAR 100, NAC LWT). Details are provided in NUREG/CR-6886 

(2009).

As discussed in Section 5.1.3, this extremely conservative scenario resulted in a fire lasting 

approximately 7 hours. The FDS analysis of that scenario was extended out to a 23-hour postfire cooldown, for a total simulation time of 30 hours. To determine the packages’ complete 

transient temperature responses, and to explore the effects of prolonged exposure to post-fire 

conditions in the tunnel, the COBRA-SFS and ANSYS analyses further extended the post-fire 

calculation to 300 hours. For boundary conditions, tunnel wall and air temperatures predicted in 

the FDS analysis at 30 hours were extrapolated from 30 hours to 300 hours using a power 

function, to realistically model cooldown of the tunnel environment. This conservative approach 

is equivalent to assuming that the package will be left in the tunnel for nearly two weeks, without 

any emergency responder intervention. 

Beyond the conservatism in the fire and location of the SNF package, a number of additional 

conservative assumptions were made to maximize heat transfer to the package during the fire 

and to minimize the heat removal rate during long-term cooldown:

• Rail car and package structure that would reduce heat transfer during the fire were 

neglected. For example, the ANSYS model of the HI-STAR 100 included the package 

cradle and rail car section beneath the package, but neglected the rail car ends and 

honeycomb end blocks adjacent to the impact limiters. The rail car was omitted in the 

COBRA-SFS model of the TN-68 and ANSYS model of the NAC LWT with the ISO 

container.

• Rather than directly use the very detailed temperature distribution and history from the FDS 

simulation, peak temperatures for specific regions were used as boundary conditions in the 

COBRA-SFS and ANSYS models. The tunnel surfaces in the ANSYS model were divided 

into three regions, consisting of the ceiling, side walls, and floor (see Figure 5.5).

• During the 7-hour fire, convection heat transfer was assumed to be forced convection and 

was based on the FDS calculated gas velocities. Beyond 7 hours, the package cooldown 

neglected any contribution of forced convection and assumed only natural convection.

• Impact limiters and neutron shield materials were assumed to retain their nominal 

properties during the fire, which would maximize heat transfer, and change to a degraded 

condition (minimizing heat transfer) for the post-fire cooldown.
6-2

• Decay heat thermal loading was at the design limit for each package (21.2 kW for the TN68, 20 kW for the HI-STAR 100, and 2.5 kW for the NAC LWT) with axial peaking factor 

from the respective SAR.

Despite all of the conservatisms built into this fire scenario, the thermal analyses showed that 

the two large packages (TN-68 and HI-STAR 100) suffer very little in this fire. This is primarily 

due to their large thermal inertia, which is also the reason the peak clad temperature is not 

reached until 40 hours after start of the fire for the TN-68 and 35 hours for the HI-STAR 100. 

These peak clad temperatures, 845°F (452°C) in the TN-68 package and 930°F (499°C) in the 

HI-STAR 100 package, are also well below the regulatory limit1 of 1058°F (570°C) for zircaloyclad SNF under accident conditions (NUREG-1536 1997). The package closure and vacuum 

port seal temperatures exceed material limits for the TN-68, however, and the potential 

consequences to package integrity are discussed in Section 7.1. The peak seal temperatures 

reached in the HI-STAR 100 are higher, but they remain below the continuous-use limit for the 

high temperature metallic seal material used in that package.

The NAC LWT has a much smaller capacity than the multi-assembly packages and 

consequently is a much lighter transport package. Therefore, it has a much lower thermal 

inertia than the other two packages considered in this accident scenario. The evolution of 

component temperatures during the fire and through 23 hours of the post-fire cooldown is 

shown in Figure 6.1. Peak clad temperature reaches a maximum of 1001°F (539°C) in just 

10 hours after the start of the fire, which is only 3 hours after the fire is out. The drain and vent 

port seals reach a maximum temperature of 1407°F (764°C), and the lid seal reaches 1356°F 

(735°C) by the end of the fire. The drain and vent ports are sealed with Teflon O-rings. The 

bolted lid is double-sealed with a metallic seal and a Teflon O-ring seal. The predicted 

maximum seal temperatures are far greater than the maximum continuous-use seal 

temperature limits of 735°F (391°C) for the Teflon seals and 800°F (427°C) for the metallic 

seals. Potential consequences for this accident scenario are discussed in Section 7.1 below.

 1 The short-term temperature limit of 1058°F (570°C) is based on creep experiments performed on two fuel cladding 

test samples which remained undamaged when held at 1058°F (570°C) for up to 30 and 71 days (Johnson et al. 

1983). This is a relatively conservative limit, since the temperature at which zircaloy fuel rods actually fail by burst 

rupture is approximately 1382°F (750°C) (Sprung et al. 2000).
6-3

Figure 6.1. NAC LWT Package Component Maximum Temperature Histories for First 

30 hours of Fire Transient – Baltimore Tunnel Fire Accident Scenario

6.2 Analysis of Caldecott Tunnel Fire Accident Scenario

The SNF package evaluated in this accident scenario is the NAC LWT. In addition to locating 

the package at the hottest location in the tunnel fire, several additional conservative modeling 

assumptions were made in the process of determining the thermal response to this fire 

scenario: 

1. Peak temperatures in each region2 were used to define boundary temperatures over the 

entire region, rather than using detailed local temperatures from the FDS simulation.

2. The package cradle and trailer bed were omitted from the ANSYS model to preclude any 

shielding they would provide from thermal radiation or blockage to forced convection heat 

transfer from the hot combustion gases.

3. The flow of hot fire gases at the location of the package was treated as forced convection 

during the fire, to maximize heat transfer rates to the package; forced convection heat 

transfer was neglected during the cooldown period, even when gas velocities were still 

significant. After the fire, only natural convection (assuming still air) was considered for the 

package.

4. Attenuation of thermal radiation during the fire due to smoke and particulates is neglected, 

and the package (or ISO container) is assumed to see peak flame temperature rather than 

tunnel surface temperatures.

 2 The tunnel surfaces in the ANSYS model were divided into three regions, consisting of the ceiling, side walls, and 

floor. 

100

300

500

700

900

1100

1300

1500

1700

0 5 10 15 20 25 30

Elapsed Time (hours)

Temperature (°F)

Fuel Cladding (Peak)

Cask Inner Surface

Cask Outer Surface

Impact Limiters

Lid Seal

Drain/Vent Port Seals

Cask Body Lead

End Lead

ISO Container

End of Fire

End of NIST 20m Transient

Fire Duration Post-Fire Duration (NIST Data) 
6-4

5. The neutron shield material (water/ethylene glycol) was assumed to remain in place until the 

average temperature exceeded the boiling temperature of the liquid (maximizing heat 

transfer to the package) and was assumed to be instantly replaced with dry air, 

conservatively neglecting the absorption of energy that would have occurred due to phase 

change of the liquid to vapor. Air material properties were assumed during cooldown 

(minimizing heat transfer from the package).

6. The gas velocities computed with the FDS model were used with a Nusselt number 

correlation to compute forced convection heat transfer coefficients at the package outer 

surfaces. This was used for the period of the actual fire and post-fire cooldown. After that 

(beyond 3 hours) natural convection heat transfer was assumed in the model.

The FDS analysis included the 40-minute fire and a 2.3 hour period of the post-fire cooldown, 

then the ANSYS model extended the cooldown to 50 hours. The FDS computed values were 

extrapolated for use as temperature boundary conditions during this period. 

Figure 6.2 shows the peak temperatures predicted with ANSYS for the various package 

components in the first hour of the transient for the NAC LWT package contained within an ISO 

container. Figure 6.3 shows the peak temperatures predicted for the package without an ISO 

container for the same boundary conditions. The time interval shown in these plots 

encompasses the intense gasoline-fueled fire (which lasted about 40 minutes), plus the first 

20 minutes of the post-fire cooldown period. Without the ISO container, temperatures of 

outboard components (i.e., package surface, vent/port seals, and impact limiters) rise somewhat 

faster than for the case with the ISO container, and reach slightly higher peak temperatures 

during the fire, but the differences are relatively small. These plots show that the temperature 

response of the package is essentially the same, with or without an ISO container, during and 

immediately after the fire. Most components reach their peak temperature values during this 

interval, closely following the high boundary temperatures during the fire and their rapid 

decrease once the gasoline is consumed. This behavior is due mainly to the low thermal inertia 

of the package, because of its relatively small physical size. 
6-5

Figure 6.2. NAC LWT Package (with ISO Container): Component Maximum 

Temperature Histories during Fire Transient – Caldecott Tunnel Fire 

Accident Scenario

Figure 6.3. NAC LWT Package (without ISO Container): Component Maximum 

Temperature Histories during Fire Transient – Caldecott Tunnel Fire 

Accident Scenario

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Elapsed Time (hours)

Temperature (°F)

Fuel Cladding (Peak) Cask Inner Surface Cask Outer Surface

Impact Limiters Lid Seal Drain/Vent Port Seals

Cask Body Lead End Lead ISO Container

End of Fire

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Elapsed Time (hours)

Temperature (°F)

Fuel Cladding (Peak) Cask Inner Surface Cask Outer Surface

Impact Limiters Lid Seal Drain/Vent Port Seals

Cask Body Lead End Lead End of Fire
6-6

For both cases, the peak temperatures in the lead shielding are considerably above the 

established operating limit of 600°F (316°C) reported in the SAR (NRC 2001b) for this material, 

and some local melting of the lead is predicted as a result. To maximize heat input during the 

transient, it was assumed that overall thermal expansion of the lead and local expansion due to 

phase change results in the lead entirely filling the cavity between the inner and outer steel 

shells of the package. For the thermal analysis, possible slumping of the lead due to melting 

was conservatively ignored, in order to maximize heat input to the package. 

Further into the post-fire cooldown, the outboard components follow the decrease in 

environmental temperatures, but the peak temperatures of the package inner surface and lid 

seal continue to rise until they reach their maximum within an hour of the end of the fire. In the 

lid seal region, the predicted maximum seal temperature is 735°F (391°C) for the case with the 

package in an ISO container, and is 794°F (423°C) without an ISO container. Both values are 

below the maximum continuous-use temperature limit of 800°F (427°C) for this metallic seal. 

The temperature response of the fuel cladding, particularly in terms of peak cladding 

temperature, is the slowest of all components in the package, due to the significant thermal 

inertia of the fuel, and because it has the longest heat transfer path to the external environment. 

For the case with the ISO container, the predicted peak fuel cladding temperature has increased 

by only about 5°F (2.8°C) by the end of the gasoline-fueled fire. For the case without the ISO 

container, the increase is slightly smaller, about 4.3°F (2.4°C). However, the peak cladding 

temperature is still rising at 3 hours into the transient, which is 2.3 hours after the end of the fire. 

This is due mainly to the decay heat generated in the fuel, which is not being removed from the 

package during the fire and for some time during the post-fire cooldown, due to the elevated 

temperatures of the package outboard components, and the higher than design-basis ambient 

temperature. 

The predicted maximum fuel cladding temperature of 544°F (284°C) for the package within an 

ISO container is not reached until about 8 hours into the transient. Without an ISO container, 

the peak clad temperature is reached approximately one hour earlier, at 7 hours into the 

transient, and the maximum temperature is somewhat lower, at 535°F (279°C). With or without 

the ISO container, the peak clad temperature does not exceed the long-term storage 

temperature limit of 752°F (400°C) in this transient. In addition, it is far below the currently 

accepted short-term temperature limit of 1058°F (570°C) for zircaloy-clad SNF under accident 

conditions (NUREG-1536 1997). 

The canister components that do exceed temperature limits are the drain and vent port seals. 

These limits are 735°F (391°C) for tetraflouro-ethylene (TFE) seals, and 550°F (288°C) for the 

alterative design Viton® seal material. For the drain and vent port seals, the predicted maximum 

temperature values 1035°F (557°C) with an ISO container, and 1288°F (698°C) without an ISO 

container), are several hundred degrees above the maximum continuous-use temperature limits 

for these seal materials. However, the ANSYS model predicts that these components are

above the maximum continuous-use temperature limit for less than two hours. The noted limits 

for the Viton®, TFE, and metallic O-ring materials are defined for continuous use, so it is 

possible that the seals might survive these temperature excursions undamaged. Full evaluation 

of seal performance in a fire scenario requires complete data on seal material response as a 

function of temperature, which generally can be provided by the manufacturer of the specific 

seals in a particular application. Such information was not available for evaluation in this study, 

and as a conservatism, seal temperatures above continuous-use limits were assumed to 

indicate seal failure (see discussion of consequences for this accident scenario in Section 7.2).
6-7

6.3 Analysis of MacArthur Maze Fire Accident Scenario

Analysis of this accident scenario required structural and thermal models. The thermal model is 

discussed first. Only a summary from the original report is provided here. See the original 

report for the full description (NUREG/CR-7206 2015).

6.3.1 Thermal Analysis of MacArthur Maze Accident Scenario

Thermal models were produced for the GA-4 package in this accident scenario using two 

different codes, ANSYS and COBRA-SFS, with different areas of detail. In general the two 

codes provided good agreement from the initial condition, corresponding to NCT, through the 

fire and cooldown. 

There are two areas of obvious interest when looking at the temperature history, 1) peak 

cladding temperature in the fuel relative to short-term and burst rupture limits, and 

2) temperature in the areas of the package seals relative to seal material limits.

COBRA-SFS and ANSYS models predict the peak cladding temperature to be near, but still 

below the 1058°F (570°C) short-term limit by the end of the 37-minute long, pre-collapse portion 

of the fire. However, the peak cladding temperature continues to rise, passing the short-term 

limit and reaching approximately 1400°F by the end of the 108-minute fire. This value is in 

excess of 1382°F (750°C), the temperature at which burst rupture of zircaloy cladding has been 

assumed in previous SNF package transportation studies (NUREG/CR-6672 2000). Burst 

rupture temperature was looked at closely for this accident scenario and results are summarized 

in Section 7.3.

Experience with modeling of SNF packages in long-duration fires (for example, see Section 6.1) 

has shown that the maximum fuel cladding temperature can occur well after the end of the fire, 

during the post-fire cooldown of the package. In addition to the rise in temperature of the fuel 

rods in response to heat input from the fire, the temperature also rises due to the high ambient 

fire temperature preventing decay heat removal from the fuel rods during the fire. This condition 

persists for some time after the fire, as long as the outboard components of the package remain

above the maximum fuel temperature. In addition, as long as the external ambient temperature 

is above the design basis (typically 100°F [38°C]), the rate of heat removal from the package will 

be less than optimal, and internal high temperatures may persist for an extended period of time. 

In the MacArthur Maze scenario, the adverse thermal conditions of this cooldown phase are

exacerbated by the presence of the concrete ‘blanket’ of the fallen overhead roadway.

The results obtained with the ANSYS model also show a sustained peak fuel region 

temperature of nearly 1400°F (760°C) for approximately 3 hours after the end of the fire (see 

Figure 6.4). The cooldown from this point is slow. The ANSYS model predicts that by 

12.2 hours after the end of the fire, the fuel region is at an essentially uniform temperature in the 

range 1167°F to 1255°F (630°C to 680°C), and the impact limiters and outer shell of the 

package are at temperatures in the range 1034°F to 1122°F (557°C to 606°C). Only after about 

12.5 hours does the package begin to experience a uniformly decreasing temperature at all 

points, including the sheltered points within the package beneath the impact limiters.
6-8

Figure 6.4. GA-4 Package Peak Component Temperatures Predicted with ANSYS 

Model for Post-fire Cooldown to 6.5 hours – MacArthur Maze Fire Accident 

Scenario

Containment boundary seals, including drain valve and port, gas sample valve and port, and 

package lid, are all at the ends of the package and covered by the impact limiters. The thermal 

insulation provided by the impact limiters allows these seals to survive the HAC fire (GA-4 

SAR), however in the higher temperature and longer duration of the MacArthur Maze fire 

scenario, the maximum short-term design limits for the seal material (800°F for 6 minutes) are 

approached during the fire and are soon exceeded as local temperatures continue to rise and 

remain elevated until the overall system begins to cool. The ANSYS model shows that peak 

temperatures in the seal region locations continue to increase for more than 4 hours after the 

end of the fire, reaching approximately 1150°F (621°C), and after 14.5 hours are still above 

1000°F (538°C). 

6.3.2 Structural Analysis of MacArthur Maze Accident Scenario

Structural analyses used to assess SNF package response in the MacArthur Maze fire scenario 

included: 

• Damage resulting from span of upper roadway falling onto SNF package

• Impact of fire and cooldown on package lid bolt clamping force

LS-DYNA (Livermore Software Technology Company 2007) was used to model the roadway 

collapse as a free-fall of the overhead span onto the GA-4 package. Despite numerous 

conservative assumptions and evaluation of multiple cases varying package location and 

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5

Elapsed Time (hours)

Peak Temperature (°F)

fuel region basket stainless steel liner

DU gamma shield stainless steel body neutron shield contents

outer surface end of fire short-term PCT limit
6-9

orientation, the conclusion was that the structure of the GA-4 package wall would remain largely 

undamaged during this fire and roadway collapse scenario. This is because the impact forces 

that could be generated in a relatively short fall of the roadway span is a small insult relative to 

the regulatory design requirement in 10 CFR 71 that the package itself must be able to survive a 

30 foot drop test onto an unyielding surface.

The analysis of clamping force history for the package lid during the fire and extended cooldown 

transient was a more critical issue. As shown in the thermal analysis, all of the package seals,

including those in the package lid, are predicted to exceed all operating limit temperatures and 

therefore cannot be assumed to remain functional. It is therefore critical that the clamping force 

provided by the closure lid bolts can be shown to remain positive at all times during the long and 

complex transient, to minimize any potential release from the package. The results of detailed 

and careful analysis of bolt performance and material response at elevated temperatures 

conservatively show that positive clamping force would be maintained throughout the fire and 

cooldown transient. The predicted magnitude of that clamping force was used in evaluations to 

determine the release estimates for this accident scenario, as summarized in Section 7.3.

6.4 Analysis of Newhall Pass Fire Accident Scenario

Two different modeling codes, ANSYS and COBRA-SFS, were used to account for different 

levels of detail in the thermal model of the GA-4 package. The package is assumed to be in 

fully engulfing fire, defined using the results of the FDS analysis for each case.

Details were carefully implemented to account for important thermal effects during the fire 

transient. The neutron shield is modeled with conduction and convection heat transfer using 

water/propylene glycol properties until the boiling point is reached at maximum design pressure 

of the tank. Beyond that point it is modeled as air with conduction and radiation heat transfer. 

Both models include the impact limiters, which are very efficient thermal insulators. In the 

ANSYS model the distribution of properties in the impact limiters was modified during the 

cooldown to account for melting and migration of the aluminum honeycomb. This change 

slowed the rate of heat transfer, which was conservative for cooldown. It was not conservative 

during the fire, so properties of an intact impact limiter were maintained during that phase of the 

simulation. 

Peak fuel temperatures predicted for all cases are shown in Table 6.1 (where “A” refers to the 

“hottest fire” location and “B” refers to the “longest fire”). These results suggest that total fire 

duration may be the most important factor in determining the response of the peak fuel 

temperature to the fire scenario. Cases NIST-01, -02, and -03 have successively shorter fire 

durations and peak cladding temperatures for the hottest fire case decrease with decreasing fire 

duration. This is shown more clearly in Figure 6.5. The same trend is followed for the longest 

fire in Figure 6.6, except for case NIST-02, where the trend is complicated by the difference in 

peak temperatures. For the hottest fire, peak temperatures for NIST-01, -02, and -03 have a 

very similar magnitude and the values decrease slightly with decreasing fire duration. For the 

longest fire, the peak temperature of NIST-02 is significantly higher, apparently due to increased 

pre-heating, and this appears to be reflected in the peak cladding temperature for that case. 

A comparison between results for NIST-01 and NIST-04 also shows the importance of fire 

duration. These are essentially the same cases except that the local fire duration is much 

shorter in NIST-04. This difference is reflected in much higher peak temperatures for NIST-04, 

but with only small differences in peak cladding temperature, unchanged or decreasing slightly 

at the hottest fire location (Figure 6.5) and increasing slightly at the longest fire location 
6-10

(Figure 6.6). Case NIST-06, compared with NIST-04, reinforces this trend; despite having a 

lower peak temperature, longer local fire duration results in higher peak cladding temperatures.

Table 6.1. GA-4 Package Maximum Peak Fuel Cladding Temperatures for All Cases –

Newhall Pass Fire Accident Scenario

Case

Peak Fire

°F (°C)

Total Fire

Duration

(hours)

Local

Fire Duration

(minutes)

ANSYS: Peak

Fuel Region

°F (°C)

COBRA-SFS:

Peak Cladding

°F (°C)

NIST-01-A 1721 (938) 5.1

65 1081 (583) 882 (472)

NIST-01-B 1579 (859) 56 954 (512) 767 (408)

NIST-02-A 1706 (930) 3.0

67 1010 (544) 818 (436)

NIST-02-B 1648 (898) 64 1020 (549) 834 (445)

NIST-03-A 1668 (909) 2.0

62 921 (494) 742 (395)

NIST-03-B 1570 (854) 64 913 (490) 745 (396)

NIST-04-A 1991 (1088) 4.7

43 1074 (579) 853 (456)

NIST-04-B 1736 (947) 36 867 (464) 693 (367)

NIST-06-A 1861 (1016) 4.5

78 1217 (659) 994 (534)

NIST-06-B 1646 (897) 43 881 (472) 702 (372)

Figure 6.5. GA-4 Package Maximum Temperatures in All Cases for “Hottest Fire” –

Newhall Pass Fire Accident Scenario
6-11

Figure 6.6. GA-4 Package Comparing Maximum Temperatures in All Cases for 

“Longest Fire” – Newhall Pass Fire Accident Scenario

These results suggest that a shorter fire can have less severe effects on an SNF package, even 

if it reaches a higher temperature than a longer fire. It is not so much the heat coming into the 

package from the fire that adversely affects the fuel; it is the lack of heat removal from the fuel 

during and after the fire, in the cooldown portion of the fire transient that is more likely to be the 

problem. 

7-1

7.0 CONSEQUENCES OF FIRE ACCIDENT SCENARIOS

Dose and release consequences for each fire accident scenario are discussed in this section. 

As noted previously, these are summaries from existing reports. For extended descriptions the 

reader should consult the original references.

The following statement regarding neutron shielding and associated dose consequence is 

typical for each fire accident scenario: SNF transport packages with liquid or hydrocarbon resin 

neutron shields are generally designed to be able to lose their neutron shielding and still meet 

regulatory accident dose limit requirements. In effect, these SNF packages require neutron 

shielding only to meet NCT requirements. Additionally, gamma shielding is not compromised, in 

just about any package, in any credible (and most incredible) accident scenarios. The salient 

point is that accidents (fire or otherwise) generally will not cause problems due to ionizing 

radiation; the problem is the potential for release of radioactive material (gases and particulate) 

due to containment boundary failure. 

7.1 Consequences of Baltimore Tunnel Fire Accident Scenario

All three of the packages considered in this evaluation can meet the regulatory limits, even 

when their neutron shielding has been destroyed by fire. There is also no impact on the gamma 

shielding for the TN-68 and HI-STAR 100, because they rely on layers of steel. The gamma 

shielding on the NAC LWT, however, is composed of lead, which will be molten for many hours 

during the fire and post-fire cooldown. A careful analysis showed that, without a puncture that 

would release this material, there is no loss of function in this gamma shield and therefore, also, 

no dose consequence.

In regard to radioactive material release, the HI-STAR 100 is expected to have none in this 

tunnel fire scenario. This is because the canister is welded and has no leak path and, as an 

additional redundancy, the metallic lid seal temperature remains below its continuous-use 

service temperature. 

The TN-68 and NAC LWT have the potential for radioactive material release under this scenario 

due to the package seal temperatures exceeding their design limits. Although the material may 

retain some sealing function (see Section 4.3), the conservative assumption must be made in 

the analysis that the seals are gone. 

Since the peak fuel cladding temperature in the TN-68 remains well below the regulatory or 

burst rupture temperature limits, the only source of radioactive material is from CRUD detaching 

from the fuel rods. Any potential release from that package would be small and is shown to be 

less than an A2 quantity. An A2 quantity1 is defined in 49 CFR 173.403 as the maximum activity 

of Class 7 (radioactive) material permitted in a Type A package. This is because an A2 quantity 

of radioactive material would not be expected to result in a significant radiological hazard to first 

responders even if it were released from the package due to a transportation accident. Type B 

packages (which include SNF transportation packages) can carry more than an A2 quantity of 

radioactive material, but must retain the integrity of containment and shielding under normal 

conditions of transport, as required by DOT regulations in 49 CFR 173. Type B packages must 

 1 The actual amount of a particular material that constitutes an A2 quantity depends on the radiological properties of 

the material. Appendix A of 10 CFR 71 defines the A2 quantities for a large number of different materials in 

Table A.1, and specifies methods for calculating the appropriate value for any material not listed in the table.
7-2

also be designed such that if one were subjected to the hypothetical accident conditions 

specified in 10 CFR 71 (2012), it would release less than an A2 quantity/week.

The release estimate from the NAC LWT is likely to be similar, less than an A2 quantity as 

concluded in the original study (NUREG/CR-6886 2009). However the higher predicted peak 

clad temperature for this package and the lower burst rupture temperature estimated in more 

recent analyses (see description of consequences for MacArthur Maze and Newhall Pass 

accident scenarios in Sections 7.3 and 7.4) suggest that the release estimate for the NAC LWT 

in the Baltimore tunnel fire scenario should be revisited. This would include an estimate of burst

rupture temperature of the postulated fuel, which depends on the temperature history during the 

accident. If the estimate is below or within the uncertainty estimate of the predicted peak 

cladding temperature, a revised release estimate should be performed2

. 

7.2 Consequences of Caldecott Tunnel Fire Accident Scenario

Neutron shielding is again not an issue, for the reasons stated above. Gamma shielding in the 

NAC LWT is provided by a 5.75-inch thick layer of lead sandwiched between the inner and outer 

steel shells of the package body and a 3-inch thick lead billet encased in the steel base of the 

package. In the severe conditions of the Caldecott Tunnel fire scenario, the process of raising 

the peak temperature of the lead to its melting point requires more than half of the total 40-

minute duration of the fire. Once the fire is over, temperatures of the gamma shielding material 

begin to decrease, and the peak temperature falls below the melting temperature of lead in less 

than 3 hours. Detailed analyses of the response of the NAC LWT package to the conditions of 

the Baltimore tunnel fire scenario, in which the duration of the fire was approximately 7 hours, 

showed that complete melting of the lead gamma shielding requires more than 8 hours of 

exposure to the intensely hot fire environment. Therefore, a large portion of the lead is not 

expected to change phase in the Caldecott Tunnel fire scenario. A careful analysis was 

completed of impact on dose for any potential localized thinning of the gamma shielding in the 

Baltimore tunnel fire scenario and gamma dose was found to remain within regulatory limits for 

accident conditions. That analysis bounds any impact that would occur in the Caldecott Tunnel 

fire accident scenario. 

NRC staff evaluated the potential for a release of radioactive material from the NAC LWT 

transportation package analyzed for the Caldecott Tunnel fire scenario. The analysis indicates 

that the possibility of a release cannot be entirely ruled out for this package because 

temperatures in the drain and vent port seal regions during the transient exceed the continuoususe temperature limits for the hydrocarbon seals (TFE or Viton®). Although the package lid 

peak temperature remains significantly below the continuous-use temperature limit for its 

metallic seal, it exceeds the continuous-use temperature limit for its TFE seal. A simple 

“pass/fail” criterion is used for evaluating seal performance in this study. If the manufacturer’s 

maximum recommended service temperature was exceeded at any time during the transient on 

any portion of the sealing surfaces, the seal was assumed to fail. Therefore no credit is taken in 

the release calculation for the presence of any seals. This is considered to be a highly 

conservative approach. 

 2 The recommended assessment of fuel burst rupture for the NAC-LWT transport cask in the Baltimore Tunnel Fire 

was completed in August, 2016. This included repeating ANSYS simulations for this cask in the Baltimore Tunnel Fire 

accident scenario and performing a conservative calculation of failure possibility using FRAPTRAN with initial 

conditions and boundary conditions provided from FRAPCON and ANSYS, respectively. The result of this calculation 

is that fuel rod failure is not expected for this scenario.
7-3

The thermal analyses conservatively show fuel cladding temperatures are not high enough to 

expect fuel rod failure as a consequence of exposure of an SNF package to this fire scenario. 

Therefore, any potential release would not involve a release of spent fuel or fission products, but 

could possibly result from CRUD detaching from the fuel rods. Rather than addressing all 

radionuclides that could be contained in such CRUD particles, most of which have relatively 

short half-lives, and are therefore unlikely to be present in significant quantities on fuel old 

enough to be eligible for dry storage, (see reference [Sandoval et al. 1991], Table I-7), the 

radionuclide of the greatest concern was used as the basis of the release calculation. For 

shipments consisting of fuel that is 5 years old or older, Co60 is the most important radionuclide 

to be considered. (For fuel that is less than 5 years old, other short-lived isotopes, such as Mn54

and Co58 should be considered as well [Sandoval et al. 1991].) For PWR fuel, the total activity 

decreases to 3% of that at discharge in 5 years, and drops to 1% after 13 years. Co60 accounts 

for 92% of the activity at 5 years and 99% at 8 years (see page I-50, Sandoval et al. 1991). 

Based on this data, the average CRUD activity for five-year-cooled PWR fuel rods is about 

0.006 curies per rod, based on a surface area of 1200 cm2 per rod. The average CRUD activity 

for a 17x17 PWR assembly is therefore about 1.73 curies.

The amount of CRUD that could flake or spall from the surface of a PWR rod due to 

temperatures calculated for the fuel rods in the thermal analysis is estimated to be a maximum 

of 15% (Sandoval et al. 1991, Table I-10). The major driving force for material release is due to 

the increased gas pressure inside the package as a result of increases in internal temperature. 

The temperature change in the package is bounded by the difference between the maximum 

gas temperature predicted during the fire transient and the gas temperature at the time the 

package is loaded. For this analysis, the loading temperature is defined as 100°F (38°C), 

based on the value reported in the SAR (NRC 2001b). The maximum gas temperature is 

assumed to be the maximum peak clad temperature predicted during the transient. This yields 

a conservative estimate of the maximum possible temperature change.

To estimate the potential release from the NAC LWT package, a methodology similar to that

developed at Sandia National Laboratory (for NUREG-6672 [Sprung et al. 2000]) was used (see 

[NUREG/CR-6894 2007]). The result of that analysis was that the potential release from the 

NAC LWT package based on five-year cooled fuel is estimated to be approximately 0.01 curies 

of Co60. Since the A2 value for Co60 is 11 curies (0.41 TBq), the potential release is about 0.001 

of an A2 quantity. Regulatory guidelines require the assumption of 100% spalling of CRUD from 

the rod surfaces HAC, but the release estimate based on the Sandia studies show that the 

amount that could be released is very small. Even if the estimated release fraction is increased 

to 100% (from the 15% used in this estimate), which constitutes a factor of 7, the activity that 

could potentially be released would be only 0.07 curies (0.0026 TBq), or 0.006 of an A2 quantity 

for this radionuclide. 

Therefore, the potential radiological hazard associated with an accident similar to the Caldecott 

Tunnel fire, if it were to involve an SNF package in close proximity to the fire source, is small. 

The probability of such an occurrence, based on tunnel accident frequency, flammable materials 

trucking accident statistics, and radioactive material shipment statistics, has been estimated as 

one such accident every million years (Larson 1983).

7.3 Consequences of MacArthur Maze Fire Accident Scenario

As in previous fire scenarios there are no adverse consequences related to loss in shielding in 

the MacArthur Maze accident scenario. The overarching concern is with the potential 
7-4

consequence of radioactive material release. Unlike the previous cases (Baltimore and 

Caldecott Tunnel fires), this accident scenario could result in fuel failure. 

Based on the predicted fuel cladding temperatures from the COBRA-SFS modeling, fuel 

performance was evaluated using the burst rupture model in the FRAPTRAN-1.4 code 

(NUREG/CR-7023 2011). In the FRAPTRAN code, cladding rupture is evaluated with a burst 

stress/strain model developed from test data obtained for loss of coolant accident analysis and 

reactivity insertion accident evaluations. Burst rupture is the expected mechanism of failure for 

fuel rods in the reactor core when subjected to severe accident conditions, and is a potential 

failure mode for spent fuel at high temperatures. 

Creep rupture is considered a possible alternative mechanism of failure for spent fuel rods. To 

evaluate this possibility, a separate analysis was performed with a creep rupture model, using

the FRAPCON-3.4 code (NUREG/CR-7022 2011) in conjunction with the DATING code 

(Simonen and Gilbert 1988). The version of the code used in this analysis has been updated 

with creep coefficients from creep tests on irradiated cladding (Gilbert et al. 2002), for the 

temperatures in the range predicted for the hottest rod in the MacArthur Maze fire scenario.

The cladding temperatures from the fire, as calculated with COBRA-SFS, and rod pressures 

calculated by FRAPCON-3.4 (NUREG/CR-7022 2011) assuming the spent fuel had been 

subjected to normal reactor operation at 5.7 kW/ft, were input into FRAPTRAN-1.4 to calculate 

the cladding stresses. The FRAPTRAN-1.4 cladding burst model was also used to calculate the 

rupture temperature during the fire. The calculated cladding temperatures during the fire from 

the COBRA-SFS analysis, and the calculated hoop stresses obtained from FRAPTRAN-1.4 for 

the fire conditions were input into FRAPCON-DATING to calculate cladding rupture based on 

the out-of-reactor creep relationship in the DATING subroutine.

The peak cladding temperatures calculated with COBRA-SFS for the MacArthur fire were 293°F 

(145°C) at the start of the fire and reached a peak cladding temperature of 1388°F (753°C) in 

the fire transient. Based on these temperatures, the calculated cladding hoop stress is 50 MPa 

at the start of the fire and reaches a peak of 121 MPa just prior to predicted cladding rupture at 

1098°F (592°C), as predicted with the burst strain model in FRAPTRAN-1.4. This relatively low 

rupture temperature reflects the conservatism in the cladding temperature history predicted in 

the thermal analysis, and the uncertainty in the FRAPTRAN predictions at the relatively low 

heating rate for the cladding in this fire scenario. 

Based on the validation range of the models in FRAPTRAN, and the conservative assumptions 

in the thermal modeling that impose an extraordinarily severe temperature transient on the fuel 

rods within the GA-4 package in this fire scenario, the predicted cladding rupture at 1098°F 

(592°C) obtained in the FRAPTRAN analysis can be considered an extremely conservative 

result. However, the predicted peak cladding temperature obtained in the thermal modeling is 

1388°F (753°C) in this fire scenario. The specific temperature value for burst rupture predicted 

with FRAPTRAN for these conditions may be quite conservative, and may have a fairly large 

uncertainty, but there is little uncertainty that the cladding would at some point fail by burst 

rupture if subjected to the severe conditions predicted for the fuel in the GA-4 package in the 

MacArthur Maze fire scenario. 

The cladding failure temperature predicted with the creep model in the DATING code is 1229°F 

(665°C), which is significantly higher than the burst rupture temperature of 1098°F (592°C) 

obtained in the FRAPTRAN analysis. The DATING code is a more general creep prediction tool 

than FRAPTRAN, with its ballooning and rupture models, which are effectively high temperature 
7-5

creep models. However, it must be noted that, as with FRAPTRAN, the DATING code is being 

applied outside its validation databases when used to evaluate cladding response to the 

conditions of the MacArthur Maze fire scenario. However, the results obtained with both 

modeling tools show that although there might be some uncertainty as to the exact temperature 

at which it would occur, fuel cladding could and probably would fail, if subjected to the severe 

conditions postulated for the MacArthur Maze fire scenario. 

The burst rupture and creep rupture models predict cladding failure at a single location along 

the axial length of a fuel rod. Based on the temperature predictions obtained with the COBRASFS model, which omits the impact limiters, the fuel performance models predict rod rupture in 

the end region of the rod. The peak fuel cladding temperatures predicted with the ANSYS 

model are somewhat higher than the peak temperatures on the rod ends predicted with 

COBRA-SFS. Temperature distributions obtained with the ANSYS model, which assumes the 

impact limiters remain in place throughout the transient, result in the highest temperatures 

occurring near the axial center of the fuel region, and rod rupture would be expected near the 

middle of the rod for this package configuration. Since the design-basis fuel for the GA-4 is low 

burnup (i.e., no more than 45 GWd/MTU), the degree of pellet-clad interaction would be 

relatively limited, and a single rod breach would be expected to effectively depressurize the fuel 

rod. Therefore, no additional ruptures are predicted on a given rod, and potential release 

calculations are based on the assumption of one rupture per rod. 

The rod temperatures in both analyses remain much higher than the predicted rupture 

temperatures for an extended period of time. Table 7.1 summarizes the elapsed time and time 

duration that the hottest rod peak temperatures are predicted to exceed the calculated burst 

rupture temperatures. 

Table 7.1. Time above Predicted Rod Rupture Temperatures in the MacArthur Maze Fire 

Scenario

Rod 

Condition

PCT at Time 

of Rupture

COBRA-SFS Model ANSYS Model

Max PCT in 

fire transient 1388°F (753°C) Max PCT in fire 

transient 1433°F (779°C)

Elapsed Time 

(hours)

Time Above 

Rupture 

Temperature 

(hours)

Elapsed Time 

(hours)

Time Above 

Rupture 

Temperature 

(hours)

rod rupture 

(burst strain 

model)

1,097°F 

(592°C) 0.8 16 0.69 >14.5

rod rupture 

(creep 

model)

1,229°F 

(665°C) 1.15 10.5 0.97 11.5

PCT = Peak Cladding Temperature

Based on the burst strain model, the fuel rods are expected to rupture before the end of the fire. 

Based on the creep rupture model, the fuel rods would also be expected to begin rupturing 

before the end of the fire, but slightly later in the transient. Furthermore, the peak temperatures 

remain significantly above these predicted rupture temperatures for more than 10 hours. The 

fuel rod temperatures continue to increase even after the end of the fire, because of thermal 

inertia and build-up of decay heat that is not removed from the package during and immediately 

after the fire. 
7-6

By the time of the secondary peak of 1348°F (731°C) in cladding temperature predicted with the 

COBRA-SFS model, which occurs at 250 minutes elapsed time (142 minutes after the end of 

the fire), the peak temperature on every rod in the package exceeds the highest temperature 

predicted for rod rupture (1229°F [665°C]). The peak temperature of 1343°F (728°C) predicted 

with the ANSYS model is at essentially the same value as that predicted with the COBRA-SFS 

model at this point in the cooldown transient. More significantly, at this time the lowest peak rod 

temperature is 1285°F (696°C) in the COBRA-SFS model results, and the lowest axial peak 

temperature predicted in the fuel region in the ANSYS model is approximately 1134°F (612°C). 

Based on these results, it must be assumed that all of the rods in each of the four assemblies in 

this package would rupture in the MacArthur Maze fire scenario and release some fraction of 

their radioactive content into the canister. The integrity of the containment boundary then 

becomes the controlling factor in any release. 

Package seal locations are shown to exceed all seal material temperature limits for long periods 

of time. Although experiments with the same material used in these seals suggest survival at 

temperatures well above design limits is possible (see discussion in Section 4.3), considerable 

additional work is needed to fully characterize seal performance at temperatures above their 

rated operating temperatures. In the evaluations of the potential consequences of the 

MacArthur Maze accident scenario, failed seals are assumed to simply vanish. Therefore 

estimating the leakage rates without seals was key to estimating material release, as was an 

estimate of the activity sources present in the package cavity. Because the peak fuel 

temperature exceeds the value where burst rupture of the zircaloy cladding can occur, the 

potential exists for a release involving fission products and spent fuel particles, as well as 

particulates resulting from CRUD detaching from fuel rod surfaces.

To estimate the potential release, source terms were generated with ORIGEN-ARP (Gauld et al. 

2009) for two design-basis fuel configurations, WE 14x14 fuel at 35 GWd/MTU burnup and 

10-years cooling and WE 15x15 at 35 GWd/MTU and 10-years cooling. Allowable release 

fractions in the Standard Review Plan for Transportation Packages for Spent Nuclear Fuel; Final 

Report, NUREG-1617 (2000) and in Containment Analysis for Type B Packages Used to 

Transport Various Contents, NUREG/CR-6487 (1996), were then used to calculate bounding A2

fractions released into the GA-4 package. 

There is little information upon which to base leakage rate from failed seals. Ultimately it was 

treated as being analogous to fluid flow through fractured material with an equivalent gap. 

Leakage between the closure lid and body flange was assumed to be the dominant leak path. 

Since a detailed finite-element analysis of the bolt tension showed that a positive clamping force 

is maintained throughout the fire and cooldown transient, the only gap will be due to the surface 

roughness and clamping force. The flow rate through a very small gap is proportional to 

pressure difference and to the cube of the gap thickness. The equivalent gap was estimated 

using literature values of conduction contact resistance for a range of contact pressure and 

related to the GA-4 using results of the bolt tension analysis. This analysis gives a maximum 

gap at the time seal failure occurs, which decreases as lid bolt tension increases during the 

cooldown transient until the gap is essentially closed. This window is estimated at less than 

3 hours, which has the effect of greatly reducing the potential for a substantial release of 

radioactivity in this accident scenario.

Release estimates were completed using the estimated release fractions into the package at a 

conservative upper bound pressure, the leak rate model with a number of conservative 

assumptions (no particulate settling, no filtration of particulate by the gap). The total release 

from the package is estimated as 21 Ci (0.78 TBq) for the higher burnup fuel, and as 24.5 Ci 
7-7

(0.91 TBq) for the lower burnup fuel. Expressed as an A2 fraction, relative to the mixture A2 for 

each configuration, these release rates are 0.24 and 0.17, respectively. Therefore, the 

bounding estimate of the total release from the package is 0.24 of the mixture A2 calculated 

assuming WE 15x15 fuel at 45 GWd/MTU, 15 years cooling. As mentioned above, if the effect 

of particulate settling and the restriction of large particulate from passing through a small gap 

were taken into account, the release estimate would be significantly reduced.

In summary, the estimated consequence of this extremely challenging fire accident scenario is a 

potential release that would still be within regulatory limits. 

7.4 Consequences of Newhall Pass Fire Accident Scenario

As in previous fire scenario analyses, loss of shielding in the GA-4 is not an issue in the Newhall 

Pass fire scenario. The concern is whether or not a release of radioactive material could occur. 

Like the MacArthur Maze fire accident scenario, this is another accident scenario that could 

result in failed fuel.

A cladding performance analysis was completed for the assumed fuel and burnup in similar 

fashion to that done for the MacArthur Maze fire scenario. In the burst rupture analyses, initial 

conditions for the hottest fuel rod were determined from a steady-state calculation using 

FRAPCON-3.4 for the design-basis fuel in the GA-4 package, WE 14x14 (standard) fuel with 

average burnup of 33 GWd/MTU, and initial room temperature pressurization of 460 psig. The 

FRAPCON calculation essentially “ages” the assembly to the internal pressure corresponding to 

its final burnup. The rod in this condition was then subjected to the time history of the maximum 

cladding surface temperatures predicted with the thermal models for the various bounding 

cases defining the Newhall Pass fire scenario, using FRAPTRAN1.4. 

Table 7.2 summarizes the results of the burst rupture analyses as applied to the five cases 

evaluated for the Newhall Pass fire scenario. These results are also illustrated graphically in 

Figure 7.1. For the peak fuel region temperature histories predicted with the ANSYS model, the 

FRAPTRAN analysis predicts burst rupture at 1038°F (559°C). For the more realistic peak fuel 

cladding temperature histories predicted with the COBRA-SFS model, the FRAPTRAN analyses 

predict that burst rupture would not occur for the conditions postulated for these bounding 

cases, although clad ballooning is predicted to occur for the most severe case (NIST-06-A). 

Creep rupture modeling evaluations were also performed for the fuel rods in the Newhall Pass 

fire scenario, using the FRAPCON-3.4 code in conjunction with the DATING code. The creep 

rupture modeling evaluations showed that fuel would not fail at the temperatures predicted for 

the Newhall Pass Tunnel fire scenario. This is consistent with the results obtained for the 

MacArthur Maze fire scenario, in which the creep rupture model predicted a rupture temperature 

of 1229°F (665°C). This temperature is not exceeded in any case of the Newhall Pass Tunnel 

fire scenario.

The burst rupture model predicts rupture at a single location along the axial length of a fuel rod. 

The temperature predictions obtained with both the COBRA-SFS model and with the ANSYS 

model show that the highest temperatures occur near the axial center of the active fuel region, 

and therefore rod rupture would be expected near the middle of the rod. As described in 

consequences for the MacArthur Maze accident scenario, a single rod breach would be 

expected to effectively depressurize the fuel rod. Therefore, potential release calculations are 

based on one rupture per rod.
7-8

Table 7.2. Results of Fuel Performance Analyses in the Newhall Pass Fire Scenario

Case

ANSYS Model Results COBRA-SFS Model Results

Peak Fuel Region 

Temperature 

(°F [°C])

Fuel Failure 

Predicted?

Maximum Peak Cladding 

Temperature

(°F [°C])

Fuel Failure 

Predicted?

NIST-01-A 1081 (583) yes 882 (472) no

NIST-01-B 954 (512) no 767 (408) no

NIST-02-A 1010 (544) no 818 (436) no

NIST-02-B 1020 (549) no 834 (445) no

NIST-03-A 921 (494) no 742 (395) no

NIST-03-B 913 (490) no 745 (396) no

NIST-04-A 1074 (579) yes 853 (456) no

NIST-04-B 867 (464) no 693 (367) no

NIST-06-A 1217 (659) yes 994 (534) no

NIST-06-B 881 (472) no 702 (372) no

Figure 7.1. Predicted Burst Rupture Temperature Compared to Maximum Fuel Rod 

Temperatures from Thermal Analysis Models – Newhall Pass Fire Accident 

Scenario

Based on the ANSYS model results, predicted maximum fuel region temperatures exceed the 

calculated burst temperature obtained in the FRAPTRAN analysis for three of the five cases 

evaluated with the package at the hottest location in the tunnel (near the center of the tunnel). 
7-9

Predicted maximum fuel region temperatures do not exceed the calculated burst temperature in 

any of the five cases with the package at the “longest fire” location (near the tunnel entrance). 

For the COBRA-SFS results, the predicted maximum fuel cladding temperature does not 

exceed the calculated burst temperature in any of the cases considered. 

The ANSYS model shows only a limited portion of the fuel reaching the burst rupture 

temperature for the indicated cases. However for the purpose of calculating the potential 

release from the GA-4 package in the Newhall Pass Tunnel fire scenario, it is assumed that all 

rods in the package fail. This is consistent with the assumptions for the HAC fire in NRC 

guidance, and effectively bounds the maximum possible release from the package. 

The thermal model results indicate that the highest temperatures reached in the seal regions 

are in the range that the seal material would be expected to withstand for up to 10 to 20 minutes 

without exceeding the documented temperature limits. However, in the Newhall Pass Tunnel 

fire scenario, the seal regions on the GA-4 package would be expected to experience elevated 

temperatures for several hours, not just a few minutes. Table 7.3 summarizes the peak 

temperatures predicted for the lid seal region for the various cases evaluated. This table reports 

the peak temperatures during the fire portion of the transient and also in the cooldown portion of 

the transient, which is when the highest seal region temperature occurs in all cases. Table 7.3

also includes the length of time the seal region is above the 30-minute exposure, 

5-hour exposure, and long-term exposure temperature limits.

Table 7.3. Summary of Peak Lid Seal Temperatures during Phases of Transient in the 

Newhall Pass Fire Accident Scenario

ANSYS lid seal temperatures summary: Total Time 

Above

30-minute 

Exposure

Limit of 520°F

(hours)

Total Time 

Above

5-hour 

Exposure

Limit of 400°F

(hours)

Total Time 

Above

Long-term 

Limit of 302°F

Case (hours)

peak seal temperature during:

“Hottest” 

Fire

(°F)

“Longest” 

Fire

(°F)

Post-fire 

Cooldown

(°F)

NIST-01-A 499 630 2.62 7.25 >7.5

NIST-01-B 486 626 2.17 5.25 >5.7

NIST-02-A 505 586 1.80 5.2 >8.4

NIST-02-B 583 649 2.50 6.1 >7.7

NIST-03-A 411 533 0.67 3.5 7.4

NIST-03-B 494 578 1.5 4.9 >8.5

NIST-04-A 455 583 1.83 5.0 >7.7

NIST-04-B 429 552 1.17 4.4 >5.8

NIST-06-A 527 668 2.8 6.2 >6.8

NIST-06-B 447 545 1.2 4.1 >5.9

The time-at-temperature results for the drain valve seal and gas sample port seal are similar to 

the results for the lid seal. The heat-up and cooldown curves for these seals slightly lag the 

corresponding time values for the lid seal, due to their more protected locations within the 

closure lid and package base, respectively. The peak temperatures on the valve seals are 

essentially the same or slightly lower than the values predicted for the lid seal, and therefore the 

temperature response of the lid seal can be considered as bounding of the behavior of all seals 

in the package. 
7-10

The results in Table 7.3 show that the highest seal temperatures occur during the cooldown 

phase of the transient, rather than during the period of fire exposure for the GA-4 package. The 

impact limiters shield the seal regions from direct exposure to the fire, and therefore limit the 

temperature rise on these components during the fire. In the post-fire cooldown of the package, 

however, the insulating effect of the impact limiters slows the rate of heat removal from the ends 

of the package, and the high temperatures developed in the central region of the package 

during the fire result in heat flowing toward the cooler ends. The temperature in these regions 

continues to increase long after the end of the fire portion of the transient. 

In all cases evaluated, the seals would be expected to maintain their sealing function through 

the local vehicle fire, and do not reach temperatures that exceed the seal material performance 

limits until sometime into the cooldown portion of the transient. This behavior has important 

consequences to be considered in the evaluation of potential release from the package. But 

regardless of the time it takes to reach seal performance limits, the predicted temperatures 

show that potential release estimates for the GA-4 package must assume that the seals fail in 

all cases considered in this fire scenario. 

Potential release from the GA-4 package in the Newhall Pass fire scenario can be estimated 

using the leak rate model and equivalent gap width relationship previously discussed in 

Section 7.3, to obtain a conservative bounding estimate for potential release of radioactive 

material from the same package in the MacArthur Maze fire scenario. The leak rate obtained 

with that model is a function primarily of the cavity gas pressure developed during the transient 

and the bolt temperature history. The conditions of pressure and temperature in the MacArthur 

Maze fire scenario effectively bound the conditions of the Newhall Pass Tunnel fire scenario. 

This is illustrated in Figure 7.2, with a comparison of the bounding cavity gas pressure 

calculated for the MacArthur Maze fire scenario, compared to the cavity gas pressure predicted 

for the bounding cases defining the Newhall Pass Tunnel fire scenario. The calculated cavity 

gas pressures conservatively neglect the effect of mass loss due to leakage, and the pressure is 

calculated based on the average cavity gas temperature, using the ideal gas law. 
7-11

Figure 7.2. Cavity Gas Pressure for Bounding Cases for Newhall Pass Tunnel Fire 

Scenario Compared to Bounding Value from the MacArthur Maze Fire 

Scenario

The plot in Figure 7.2 clearly shows that for the bounding conditions defined to model the 

Newhall Pass Tunnel fire scenario, the cavity gas pressure is significantly lower than that 

predicted for the MacArthur Maze fire scenario. Similarly, the gas temperature and the package 

component temperatures (including the lid and lid closure bolts) are lower in the results obtained 

for the Newhall Pass Tunnel fire scenario. The results obtained with this leak rate model for the 

MacArthur Maze fire are bounding for the Newhall Pass Tunnel fire scenario.

8-1

8.0 CONCLUSIONS AND RECOMMENDATIONS

The NRC has completed studies of truck and rail transport accidents involving fires relative to 

regulatory requirements for shipment of commercial SNF. NRC conducted case studies for 

accident scenarios involving four of the most severe of these fires and the results have been 

compared with existing regulatory requirements for SNF containers. Summaries of analyses of 

package response and potential consequences from these fire accident case studies are 

provided in this report.

The case study NRC conducted specifically for rail transport was the Baltimore tunnel fire 

accident scenario. As concluded in that study (NUREG/CR-6886 2009), the incidence of 

accidents on railways involving fires, coupled with rules (e.g., limit 2-track tunnels to single train 

with SNF) and planned procedural actions to minimize or exclude involvement of transportation 

of other hazardous materials, make accidents such as the one analyzed in this scenario a very 

low probability event. Therefore, specific to rail transport of SNF, the findings summarized in 

this report support the recommendations in a recent U.S. Department of Energy study (DOE 

2009) on planned rail use for a majority (possibly even greater than 90%) of future SNF 

transport.

The three other case studies performed by NRC addressed truck transport of SNF on public 

roadways. These include the Caldecott Tunnel fire accident scenario (NUREG/CR-6894 2007), 

the MacArthur Maze accident scenario (NUREG/CR-7206 2016), and the Newhall Pass 

accident scenario (NUREG/CR-7207 2016). For roadway transport of SNF, it is recommended 

that route selection and approval should be completed in accordance with Federal requirements 

and include consideration of preplanned administrative controls (e.g., temporary lane closure) 

and alternate routes to address the impact of the current status (e.g., including seasonal 

weather changes, tunnel activity, or construction activity) that may impact the severity of an 

accident involving fire.

The severe fires case studies summarized in this report showed that the main factor driving a 

potential release is not the fire itself, but rather the impediment to getting decay heat out of the 

package during the fire and post-fire cooldown.

Regarding the adequacy of the current HAC fire test specifications, findings of response 

analyses for severe (extra-regulatory) fires include:

• These analyses confirmed that failure of shielding is not an issue in fire accident scenarios

for SNF packages. Packages are designed to meet regulatory requirements in any credible 

loss-of-shielding scenario, including fire accidents.

• Packages are shown to be extremely robust in their response to severe, real-world accident 

scenarios.

• Analyses of conservative, bounding representations of severe fire accident scenarios were

predicted to have less than an A2 quantity release. 

Results of NRC conducted seal testing (NUREG/CR-7115 2015) show some continued sealing 

effectiveness at elevated temperatures and are encouraging from the standpoint of lower 

potential releases in the event of an accident. However, the sealing function demonstrated at 

elevated temperatures has not shown consistent performance; therefore for the purpose of 
8-2

safety analysis, when temperatures in the area of the seal exceed the rated values provided by 

the seal manufacturer, the seal must be assumed to have failed as part of the containment 

analyses.

The combined summary of work on fire accidents demonstrates that current NRC regulations 

and packaging standards provide a high degree of protection to the public health and safety 

against releases of radioactive material during real-life transportation accidents.
9-1

9.0 REFERENCES

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9-2

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Spent Nuclear Fuel and High-Level Radioactive Waste in the United States, National Academy 

Press.

NRC – U.S. Nuclear Regulatory Commission. 2008. Analysis of Structural Material Exposed to 

a Severe Fire Environment – Final Letter Report, Contract NRC-02-07-006, prepared by 

Southwest Research Institute and Center for Nuclear Waste Regulatory Analyses, San Antonio, 

Texas, published by U.S. Nuclear Regulatory Commission, Washington, D.C.

NRC Docket Number 71-9225. 2001. Legal Weight Truck Transport (LWT) Packaging Safety 

Analysis Report, July 2000, Rev. 2; September 2001, Rev. 33; Rev. 34. Nuclear Assurance 

Corporation, Atlanta, Georgia.

NRC Docket Number 71-9293. 2000. TN-68 Transport Packaging Safety Analysis Report, 

Rev. 2, TransNuclear Incorporated, New York.

NRC Docket Number 72-1008. 2001. Final Safety Analysis Report for HOLTEC International 

Storage Transport and Repository Cask System (HI-STAR 100 Cask System). HI-210610, 

Vol. I and II. HOLTEC, Marlton, New Jersey.

NTSB/HAR-83/01. 1983. Multiple Vehicle Collisions and Fire: Caldecott Tunnel, near Oakland, 

California, April 7, 1982. National Transportation Safety Board, Bureau of Accident 

Investigation, Washington, D.C. 

NUREG-0630. 1980. Cladding Swelling and Rupture Models for LOCA Analysis. U.S. Nuclear 

Regulatory Commission, Washington, D.C.

NUREG/CR-0344. 1980. Embrittlement Criteria for Zircaloy Cladding Applicable to Accident 

Situations in Light-Water Reactors: Summary Report. U.S. Nuclear Regulatory Commission, 

Washington, D.C.
9-4

NUREG/CR-6487. 1996. Containment Analysis for Type B Packages Used to Transport 

Various Contents. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG/CR-6672. 2000. Re-examination of Spent Fuel Shipment Risk Estimates. 

U.S. Nuclear Regulatory Commission, Washington, D.C. 

NUREG/CR-6886, Rev. 2. 2009. Spent Fuel Transportation Package Response to the 

Baltimore Tunnel Fire Scenario. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG/CR-6894, Rev. 1. 2007. Spent Fuel Transportation Package Response to the 

Caldecott Tunnel Fire Scenario. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG/CR-7022, Vol. 1. 2011. FRAPCON-3.4: A Computer Code for the Calculation of 

Steady-State Thermal-Mechanical Behavior of Oxide Fuel Rods for High Burnup. U.S. Nuclear 

Regulatory Commission, Washington, D.C.

NUREG/CR-7023, Vol. 1. 2011. FRAPTRAN 1.4: A Computer Code for the Transient Analysis 

of Oxide Fuel Rods. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG/CR-7034. 2011. Analysis of Severe Railway Accidents Involving Long Duration Fires.

U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG/CR-7035. 2011. Analysis of Severe Roadway Accidents Involving Long Duration 

Fires. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG/CR-7101. 2011. Structural Material Analyses of the Newhall Pass Tunnel Fire, 2007. 

U.S. Nuclear Regulatory Commission, Washington, D.C. 

NUREG/CR-7115, Rev. 1. 2015. Performance of Metal and Polymeric O-Ring Seals in 

Beyond-Design-Basis Temperature Excursions. U.S. Nuclear Regulatory Commission, 

Washington, D.C.

NUREG/CR-7206. PNNL-23701. 2016. Spent Fuel Transportation Package Response to the 

MacArthur Maze Fire Scenario. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG/CR-7207. PNNL-23708. 2016. Spent Fuel Transportation Package Response to the 

Newhall Pass Fire Scenario. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG-0170. 1977. Final Environmental Statement on the Transportation of Radioactive 

Material by Air and Other Modes. U.S. Nuclear Regulatory Commission, Washington, D.C. 

NUREG-1536. 1997. Standard Review Plan for Dry Cask Storage Systems. U.S. Nuclear 

Regulatory Commission, Washington, D.C.

NUREG-1617. 2000. Standard Review Plan for Transportation Packages for Spent Nuclear 

Fuel: Final Report. U.S. Nuclear Regulatory Commission, Washington, D.C.

NUREG-2152. 2013. Computational Fluid Dynamics Best Practice Guidelines for Dry Cask 

Applications. U.S. Nuclear Regulatory Commission, Washington, D.C.
9-5

Rector DR, RA McCann, UP Jenquin, CM Heeb, JM Creer, and CL Wheeler. 1986. CASTOR1C Spent Fuel Storage Cask Decay Heat, Heat Transfer and Shielding Analysis. PNL-5974. 

Pacific Northwest Laboratory, Richland, Washington.

Sandoval RP, RE Einziger, H Jordan, AP Malinauskas, and WJ Mings. 1991. Estimate of 

CRUD Contribution to Shipping Cask Containment Requirements. SAND88-1358. Sandia

National Laboratories, Albuquerque, New Mexico.

Simonen EP and ER Gilbert. 1988. DATING – A Computer Code for Determining Allowable 

Temperatures for Dry Storage of Spent Fuel in Inert and Nitrogen Gases. PNL-6639, UC-85, 

Pacific Northwest Laboratory, Richland, Washington.

Sprung JL, DJ Ammerman, NL Breivik, RJ Dukart, and FL Kanipe. 2000. Reexamination of 

Spent Fuel Shipment Risk Estimates, NUREG/CR-6672, Vol. 1 (SAND2000-0234). Sandia 

National Laboratories, Albuquerque, New Mexico.

10-1

10.0 APPENDIX

RESPONSES TO PUBLIC COMMENTS ON NUREG/CR-7209

The NRC issued NUREG/CR-7209, “A Compendium of Spent Fuel Transportation Package 

Response Analyses to Severe Fire Accident Scenarios,” (Agencywide Documents Access and 

Management System (ADAMS) Accession No. ML16015A016) for a 60-day public comment 

period beginning January 20, 2016. The purpose of this appendix is to list public comments 

received, NRC staff’s response to each comment, and any associated changes to NUREG/CR7209 resulting from the comment. 

The NRC received public comments from the following sources:

1. Comments from Marilyn Brown

2. Comments from Rochelle Becker (Alliance for Nuclear Responsibility)

3. Comments from Gene Nelson

4. Comments from Carl Wurtz

5. Comments from Debbie Highfill

6. Comments from Milton Carrigan

7. Comments from Emmanuela Raquelle

8. Comments from Jill ZamEk

9. Comments from Erik Layman

10. Comments from Meredith Angwin

11. Comments from Linda Seeley (San Luis Obispo Mothers for Peace)

12. Comments from Henriette Groot

13. Comments from Gina Mori

14. Comments from Rosemary and Cal Wilvert

15. Comments from Ron Rattner

16. Comments from Simone Malboeuf

17. Comments from Peggy Koteen

18. Comments from Barbara Scott

19. Comments from Carl Holder

20. Comments from Anonymous Anonymous 1

21. Comments from Eric Greening

22. Comments from Lucy Jane Swanson

23. Comments from Anonymous Anonymous 2

24. Comments from Peg Pinard

25. Comments from Anonymous Anonymous 3

26. Comments from Kelly Reed

27. Comments from Anonymous Anonymous 4

28. Comments from Kathleen Oliver

29. Comments from Abram Perlstein

30. Comments from Jean’ne Blackwell

31. Comments from Robert Fronczak (Association of American Railroads)

32. Comments from Carole Anonymous

33. Comments from Franklin Frank
10-2

34. Comments from Elizabeth Brousse

35. Comments from Gary Kirkland

36. Comments from Romola Georgia

37. Comments from Betty Winholtz

38. Comments from Anonymous Anonymous 5

39. Comments from Don Andrade

40. Comments from Barbara Field

41. Comments from Janet Lester

42. Comments from Robert Halstead (Agency for Nuclear Projects, State of Nevada)

43. Comments from Robert Greene
10-3

Comment 1: Marilyn Brown

MB-1 I am writing this out of great concern over the proposed transport of high-level nuclear

waste by rail to a repository; the location of which remains undesignated as of this time. I reside

in San Luis Obispo County, the home of the last operating nuclear generating facility in

California.

Recently thousands of individuals and many institutions, school districts, health organizations,

city administrators from cities all along the rail route and more have spoken out to the regulatory

agencies here about the grave dangers of transporting highly volatile crude oil through their

towns along the railway.

Now coupled with this eventuality, we recognize the possibility that the NRC may allow trains to

transport high-level nuclear waste from not only Diablo Canyon Nuclear Generating Plant but also

the ones that have been decommissioned.

Much study has been done on this issue from the safety record of rail transport to health effects

of particulate matter exhausted from locomotives, to the inadequacy of first responders in case

of derailments and explosions, to evacuation scenarios, to aging superstructure of rails and

bridges, and so much more.

Response: The NRC staff notes the comment. Other agencies oversee and regulate the 

training or response of first responders, site evacuations, and aging rail and bridge

infrastructure. Since these areas are not under the purview of the NRC, these issues are out of 

scope of this NUREG.

MB-2 The number of accidents has increased exponentially along with the increase in use of

railroad tank cars loaded to capacity with crude oil. The study that NRC relies upon is outdated

and in need of major revision as we have now experienced 10 major accidents over five years.

Response: NUREG/CR-7209 is a compendium (compilation summary) of analyses that the 

NRC previously published. The survey of railway accidents described in Section 3.1 of 

NUREG/CR-7209 refers to an analysis published in NUREG/CR-7034 (published in 2011) that 

reflects the railway accident statistics for the period described in that publication; it does not 

indicate current accident rates.

MB-3 The requirement that tank cars carrying hazardous materials must be separated from

those carrying radioactive waste by at least one buffer car is not taking into account the passing

of other trains or be switched through a rail yard containing trains carrying hazardous materials.

Response: The U.S. Department of Transportation has the statutory authority under the 

Hazardous Materials Transportation Act to regulate the transportation of hazardous materials by 

all modes, including rail, roadway, air, and water vessel. Comments on rail transport regulations

can be sent to the following address:

Office of Hazardous Materials Safety

Pipeline and Hazardous Materials Safety Administration

U.S. Department of Transportation

1200 New Jersey Avenue, SE.

Washington, D.C. 20590-0001
10-4

MB-4 The time is approaching for critical measures to be taken for public and property safety as

more nuclear facilities are decommissioned and waste will be either transported or secured in

place. We are in a very seismically active area – as is all of California, so the answers are not

easy. But future generations depend on us to do the right things now so there will be a future

for life on Earth.

Response: The NRC staff notes the comment; however, the subject of this comment is out of 

the scope of this NUREG.

Comment 2: Rochelle Becker (Alliance for Nuclear Responsibility)

RB-1 The Alliance for Nuclear Responsibility (A4NR) wishes to provide the following 

comments to the NRC’s draft report in the matter of spent fuel transportation safety viz. 

packaging and response to severe fire accident scenarios. A4NR is a utility ratepayer 

watchdog, with a primary focus on California’s investor owned utility nuclear power plants, both

operating and decommissioned. With the decommissioning of San Onofre (SONGS) 

underway, and the older Humboldt Bay facility ongoing, ratepayers have a vested interest in

the disposition of the high level radioactive waste now stored on California’s seismically 

vulnerable coast, and its ultimate disposition outside state borders. If the waste from

SONGS were to leave California by rail, any route would pass within the perimeter of the Los

Angeles-Riverside-San Bernardino County corridor, potentially exposing millions of residents

to risk.

Our principle concern is that the data the NRC is relying upon to make their assumptions 

regarding the risks and probability of rail-related accidents and fires is insufficient and 

outdated. While this study was released in 2015, the data upon which the NRC relies was 

collected between 1997 and 2008:

The study found that the number of accidents involving the release of hazardous material has

been decreasing and, because of that, accident data from the past 12 years (1997 to 2008) 

were used to calculate current accident rates.1

1 US Nuclear Regulatory Commission, A Compendium of Spent Fuel Transportation Package

Response Analyses to Severe Fire Accident Scenarios (ML16015A016), January 2016, p.3-1

Response: NUREG/CR-7209 is a compendium (compilation summary) of analyses that NRC 

previously published. The survey of railway accidents described in Section 3.1 of NUREG/CR7209 refers to an analysis published in NUREG/CR-7034 (2011) that reflects the railway 

accident statistics for the period described in that publication; it does not indicate current 

accident rates.

RB-2 In fact, the NRC is correct, and date from the National Transportation Safety

Board and PHMSA would agree. However, in choosing 2008 as the end date for its data

collection, the NRC misses an alarming and more recent trend.

With the development of domestic gas and oil production, largely spurred by the growth in 

hydraulic fracturing (“fracking”) for Bakken crude and shale oil, transportation of highly 

volatile crude via rail car increased exponentially in the years following the NRC’s cutoff 

date of 2008.
10-5

As Reuters reported on January 9, 2014 in the wake of a fiery oil tank car derailment in 

New Brunswick, Canada, earlier that week:

The number of tank cars loaded with crude oil has risen 100-fold since

2006, according to the AAR, [American Association of Railroads] and 

there has been a similar surge in tank car originations of ethanol. 

More tank cars are being loaded with crude and ethanol and travelling

along more miles of track than ever before. As the number of

barrel-miles travelled has grown exponentially, it is not surprising

that risks have become more apparent. The number of serious

derailments and conflagrations involving ethanol and crude has

increased alarmingly. Between 2006 and 2011, a period of six years,

almost 1.4 million tank cars travelled on the railroads loaded with

ethanol, according to the task force. Just 163 (0.01 percent) were

involved in derailments in 10 separate incidents. In 2013, however,

around 400,000 tank cars were loaded with crude oil in a single

year, with almost as many originated with ethanol. Taking the

derailment rate as 0.01 percent, around 70 tank cars will derail each

year.

2

This more current data provides a more current and concerning basis on which to consider 

regulation than the NRC’s sampling of 1997-2008:

Using the railway accident data from the past 12 years (1997 to

2008) and this definition of severe fires, only nine such accidents

were identified. (The specific causes were not identified for these

nine accidents.) The occurrence of nine accidents over twelve years

was used by the authors to estimate a frequency of occurrence of

severe railway fire accidents of 6.2x10-4 accidents per million freight

train-km (1x10-3 accidents per million freight train-mi).3

In fact, the US Congressional Research Service report, “U.S. Rail Transportation of Crude

Oil: Background and Issues for Congress” (December 2014) notes this shortfall in current

data:

Each mode of oil transportation—pipelines, vessels, rail, and tanker

trucks—involves some risk of oil spills. Over the period 1996-2007,

railroads consistently spilled less crude oil per ton-mile than trucks or 

pipelines. However, the data in Figure 3 precede the recent dramatic

increase in oil transportation by rail.

4

[emphasis added]

The Congressional Research Service (CRS) then adds:

The increasing deployment of unit trains changes the risks involved in 

shipping oil by rail in two ways. Unit trains of crude oil concentrate a 

large amount of potentially environmentally harmful and flammable

material, increasing the probability that, should an accident

occur, large fires and explosions could result. This risk is similar

to that of unit trains carrying ethanol, and maybe greater than that of

mixed freight trains in which various hazardous materials, such as
10-6

explosives and toxic-by-inhalation materials, are sequenced among

other cars according to federal regulations.5 [emphasis added]

In a table of rail tank car accidents (attached as Figure 1), the CRS notes that from 2013 to

2014 there were at least eight newsworthy tank car derailments, of which 6 resulted in 

fireballs or explosions that burned for more than 30 minutes. This list does not include:

• Two ethanol train accidents in 2011 both resulting in highly visible fireballs, one in 

Illinois and one in Ohio

• The February 16, 2014 Mt. Carbon, West Virginia tank car explosion

• Two incidents in 2015 resulting in tank car fires and explosions: Galena, Illinois 

(March 5, 2015) and Heimdal, North Dakota (May 5, 2015)
10-7

Figure 1
10-8

Photographs of these more recent tank car fires/explosions are attached as Figure 2.

Figure 2

Taken as a whole, the accidents of the years 2011-2015 make clear that the NRC’s 

assumption that, “The occurrence of nine accidents over twelve years was used by

the authors to estimate a frequency of occurrence of severe railway fire accidents of

6.2x10-4 accidents per million freight train-km (1x10-3 accidents per million freight trainmi)” is badly out of date, out of touch with current realities, and in need of major revision,

as we have now experienced 10 major accidents over five years.

2 Reuters, Rail industry has underestimated risks of tank cars, January 9, 201fire accidents of 6.2x10-4

accidents per million freight train-km (1x10-3 accidents per million freight train-mi).3
10-9

3 US Nuclear Regulatory Commission, A Compendium of Spent Fuel Transportation Package

Response Analyses to Severe Fire Accident Scenarios (ML16015A016), January 2016, p.3-1.

4 US Congressional Research Service report, “U.S. Rail Transportation of Crude Oil: Background

and Issues for Congress” (December 2014), p. 10.

5 Ibid., p. 12.

Response: In regards to the rail statistics, NUREG/CR-7209 is a compendium (compilation 

summary) of analyses that NRC previously published. The survey of railway accidents 

described in Section 3.1 of NUREG/CR-7209 refers to an analysis published in 

NUREG/CR-7034 (2011) that reflects the railway accident statistics for the period described 

in that publication; it does not indicate current accident rates.

Under the Hazardous Materials Transportation Act, the U.S. Department of Transportation 

(DOT) has the statutory authority to regulate the transportation of hazardous materials by all 

modes, including rail, roadway, air, and water vessel. Recent DOT actions that address the 

transport of crude oil can be found at:

http://www.phmsa.dot.gov/hazmat/safe-transportation-of-energy-products

These DOT actions include implementing the May 1, 2015 Final Rule: “Enhanced Tank Car 

Standards and Operational Controls for High-Hazard Flammable Trains,” which includes 

enhanced braking, enhanced standards for tank cars used in high-hazard flammable unit 

trains, and reduced operating speeds. 

Comments on rail transport regulations can be sent to the following address:

Office of Hazardous Materials Safety

Pipeline and Hazardous Materials Safety Administration

U.S. Department of Transportation

1200 New Jersey Avenue, SE

Washington, D.C. 20590-0001

RB-3 The NRC, in its evaluation, also used the following assumption:

The approach taken in this study (NUREG/CR-7034 2011) was to identify

historic railway fires as a severe fire if they had a reasonable potential to 

approach a fully engulfing fire under the 10 CFR 71 definition. In their 

analysis, the two criteria for this were, 1) that a railcar “must have been 

substantially engulfed in a fire that persists for an extended period of 

time”, and 2) that the principal source of fuel for the substantially 

engulfing fire must have been derived from another railcar.”6

A4NR suggests that the NRC consider and evaluate all the above mentioned incidents 

during the period 2011-2015 to see if they fit the two principal criteria. Without attempting

to prejudge the conclusions, based on the visual evidence of the fires portrayed in attached

Figure 2, it appears that these incidents would meet the criteria.

6 US Nuclear Regulatory Commission, A Compendium of Spent Fuel Transportation Package Response 

Analyses to Severe Fire Accident Scenarios (ML16015A016), January 2016, p.3-1.
10-10

Response: As mentioned previously, NUREG/CR-7209 is a compendium (compilation 

summary) of extra-regulatory severe fire analyses that NRC previously published. These 

analyses included those describing a Baltimore tunnel fire scenario (NUREG/CR-6886), 

Caldecott Tunnel fire scenario (NUREG/CR-6894), MacArthur Maze fire scenario 

(NUREG/CR-7206), and Newhall Pass fire scenario (NUREG/CR-7207). The compendium 

does not purport to analyze all accidents or recent accidents.

RB-4 Further, the NRC document states:

Historically many of the fires resulting from rail accidents have involved 

the leakage of flammable gas (such as propane), rather than a liquid.

A flammable gas cannot form a pool. If ignited, flammable gas

leaking from a tank car will generally result in a localized pressure fire

that is incapable of engulfing a spent fuel transportation package.7

However, as the CRS report also makes evident, the more recent half-decade of rail

accidents involve highly volatile Bakken crude and other shale oil products that are both 

liquid and flammable. Therefore, the NRC’s “historical” assumption in this paragraph 

needs to be revised.

7 US Nuclear Regulatory Commission, A Compendium of Spent Fuel Transportation Package

Response Analyses to Severe Fire Accident Scenarios (ML16015A016), January 2016, p.3-3.

Response: In using the word “historically” the NRC staff did not mean to imply a statistical 

quantity. The NRC staff did not consider historical (at the time of publishing 

NUREG/CR-6886 in 2009) aspects of flammable gas fires in choosing the accidents to 

analyze in NUREG/CR-7209. In fact, the fuel that the NRC staff considered in the four 

accident scenarios were liquid and solid, not flammable gas. However, the staff edited the 

text to remove the word “historically” in order to prevent misunderstanding. 

RB-5 Finally, the NRC notes:

Federal regulations issued by the DOT, in 49 CFR 174.85, require very specifically defined

spacing between rail cars carrying radioactive materials and hazardous materials of

any kind, including flammable liquids. Typical requirements specify that a rail car

carrying radioactive material must be separated from cars carrying other hazardous

material by at least one buffer car. A rail car carrying a spent fuel package would not be 

coupled directly to a tank car carrying flammable or combustible liquid.8

All of the NRC’s above referenced assumptions may be true. However, the “uncertainty”

they fail to capture is that the special, unique “waste train” (buffered within its own 

consist) will likely at some point in its journey need to pass by an oil tank train, be

switched through a rail yard containing oil tank trains, or find itself stopped alongside or 

holding on a rail siding while an oil tank train passes. While it may be possible to 

segregate the waste-holding railcar within its own train, it may not be possible to segregate

it from other trains carrying potentially explosive liquids on the thousands of miles of 

railroad that crisscross the nation and link reactor sites with potential waste repositories. 

The probability—and possibility—of an accident occurring at one of these locations needs

to be factored into any study or analysis.

8 Ibid.
10-11

Response: The U.S. Department of Transportation (DOT) has the statutory authority under 

the Hazardous Materials Transportation Act to regulate the transportation of hazardous 

materials by all modes, including rail, roadway, air, and water vessel. Recent DOT actions 

that address the transport of crude oil can be found at:

http://www.phmsa.dot.gov/hazmat/safe-transportation-of-energy-products

These DOT actions include implementing the May 1, 2015 Final Rule: “Enhanced Tank Car 

Standards and Operational Controls for High-Hazard Flammable Trains,” which include 

enhanced braking, enhanced standards for tank cars used in high-hazard flammable unit 

trains, and reduced operating speeds.

In addition, as mentioned in Section 3.3 and Section 8 of NUREG/CR-7209, rail standards 

(e.g., “no-pass” rule, AAR S-2043), procedural actions, and administrative controls are 

additional measures that offer enhancements to the rail transport safety for spent nuclear 

fuels.

Comments on rail transport regulations can be sent to the following address:

Office of Hazardous Materials Safety

Pipeline and Hazardous Materials Safety Administration

U.S. Department of Transportation

1200 New Jersey Avenue, SE.

Washington, D.C. 20590-0001

RB-6 Moving high level radioactive waste will be a growing concern as more reactors

continue to shut down and enter the decommissioning phase. California has seen this

with 3 major facilities—Humboldt, Rancho Seco and San Onofre. On-site storage on our

seismic coast presents hazards and challenges; yet moving waste away from our state

presents a different set of concerns. None of the answers will be easy, and ratepayers

have justifiable anger and mistrust of the federal agencies (DOE, NRC and Congress)

that have allowed the problem to exist for decades without Response. The NRC draft

document that is the subject of this critique is but one of many in the long road to

solving the problems of radioactive waste. As we hope to have made clear, it deserves

the only the most recent and robust data from which to draw conclusions. We look

forward to further engagement in the process.

Response: The NRC staff notes the comment.

Comment 3: Gene Nelson

GN-1 As Government Liaison for Californians for Green Nuclear Power http://CGNP.org, I 

strongly endorse the conclusion contained in the abstract to the 110-page Pacific Northwest 

Laboratories draft report prepared by J. A, Fort, J.M. Cuta, and H. E. Adkins, Jr. released in 

January 2016 as NUREG/CR-7209 PNNL-24792, "A Compendium of Spent Fuel 

Transportation Package Response Analyses to Severe Fire Accident Scenarios."

“The combined summary of this work on fire accidents demonstrates that current U.S. Nuclear 

Regulatory Commission regulations and packaging standards provide a high degree of 
10-12

protection to the public health and safety against releases of radioactive material in real-world 

transportation accidents, were such events to involve (Spent Nucle.ar Fuel) SNF containers.”

Since “a (moving) picture is worth a thousand words,” here is an excellent summary online video 

regarding the safety of SNF casks with a web link. For archival purposes, the downloaded 

highest resolution video is only 12,989 KB. (Unfortunately, this website does not permit videos 

to be uploaded.)

Rocket Powered Trains and Trucks in Sandia Laboratories Spent Nuclear Fuel Cask Tests –

1978.

Published by uswine on Oct 29, 2014 https:

Restored at 720 HD from a 1978 Sandia Laboratories 3 minute and 6 second color film, we see 

two rocket powered trucks carrying spent fuel containers crashing into massive barriers, a 

rocket powered locomotive impacting a truck carrying a spent fuel container stopped in front of 

the locomotive on train tracks, and a rocket-powered transport car being impacted into a 

massive barrier, then being engulfed in burning jet fuel for 90 minutes. In all cases, the spent 

fuel containers would safely contain the spent nuclear fuel.

Response: The NRC staff notes the comment. The staff determined that the link 

https: is not related to NUREG/CR-7209 and is therefore out of 

scope.

Comment 4: Carl Wurtz

CW-1 My comment is regarding Conclusions and Recommendations in NRC's draft report 

(8-1). I am in agreement with NRC's conclusion that "These analyses confirmed that failure of 

shielding is not an issue in fire accident scenarios for SNF packages. Packages are designed 

to meet regulatory requirements in any credible loss-of-shielding scenario, including fire 

accidents. Packages are shown to be extremely robust in their response to severe, real-world 

accident scenarios. Analyses of conservative, bounding representations of severe fire accident 

scenarios are predicted to have less than an A2 quantity release."

Though it's impossible to predict all potential accident situations with certainty, NRC has 

undertaken an extraordinarily robust and comprehensive effort to ensure public safety. In my 

opinion, the methods which are used to ship SNF represent an infinitesimal risk to the public, far 

outweighed by nuclear energy's overall value to society and protecting the earth's climate.

Response: The NRC staff notes the comment.

Comment 5: Debbie Highfill

The proposed NUREG/CR-7209 does not take a detailed look at what is involved in moving 

canisters containing highly radioactive and long lived nuclear waste in land transport.

These are some of my main concerns:

DH-1 NRC regulations do not allow the transportation of canisters with even partial cracks 

(10 CFR 71.85 Packaging and Transportation of Radioactive Materials). Neither the outside or 
10-13

inside structure of these thin walled welded canisters can be inspected, let alone repaired. Other 

countries use thick-walled casks that do not have these problems.

The thin-walled canisters storing the fuel rods are inadequate. In order to transport the 

canisters, the fuel rods will have to be transferred to a transport cask; however, the fragile, 

"thick” canisters may likely be leaking radiation at the time of transfer, making transfer itself a 

potentially lethal undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulation include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

DH-2 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is a very realistic concern. With the rise in international terrorism, the targeting of nuclear power 

plants by ISIL, the oversized, slow-moving trucks transporting nuclear are obviously and easy 

and tempting target.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

Comment 6: Milton Carrigan

MC-1 Argument against massive and unnecessary radioactive waste transportation to Yucca 

Mt or another centralized interim storage site.

If Yucca Mt were approved for storage of nuclear waste (i.e., highly radioactive "spent" nuclear 

fuel rods, the byproducts of nuclear power generation) currently stored on local sites where It 

was produced, 43 states and more than 100 cities of 100,000 or more would be impacted by the 

use of projected road, rail, and barge nuclear waste routes. According to projections, 9,495 

containers would be shipped by rail, and 2,650 shipped by truck shipments, for a total of 12,145 

containers traveling across our nation. At least 50 million people live within 3 miles of the 

projected transport routes (Data cited sourced from documentation produced by the NIRS 

(Nuclear Information and Resource Service [www.nirs.org]).

Yucca Mt could hold only part of the total waste stored. Also, moving this 64,000 MTU of waste 

to Yucca would likely take at least 20 years of continuous shipments. If only trucks were to be 

used, the number could be as high as 60,000 shipments.

Accidents are tied to shipment miles. The DOE risk assessment under this scenario projects 50 

to 260 accidents and 250 to 590 incidents over two decades of transport. This waste is 

thermally hot, and this is a challenge in packaging and moving the waste. Even perfect 

containers emit waves of radiation (gamma); it's as if the containers were X-ray machines going 

down the road in the "on" position. Shielding sufficient to stop this radiation would make the 

containers too heavy to move. Also, casks used to ship spent nuclear fuel are NOT required to 
10-14

be physically tested: certification is provided by the NRC based only on computer simulations 

and scale model tests.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

MC-2 Radioactive Waste Management Associates of New York studied the rail tunnel fire in 

Baltimore in July 2001 and concluded that such conditions would breach a canister had the train 

carried "spent" fuel. Nuclear waste in that tunnel fire would have contaminated large areas of 

Baltimore, caused over 31,800 latent cancer fatalities over 50 years. Cleaning up costs were 

estimated to exceed $13.7 billion.

The plans that Congress is working on would merely transfer accumulated nuclear waste to a 

different location (consolidated storage) with no improvement in the technology while adding 

and compounding the hazards of transport.

As a nation, we can ill afford the significant additional hazards of transport, in terms of the 

potential loss of lives, and contamination of cities as well as our agricultural heartland. The 

solution to the problem of accumulating radioactive waste must be ending its generation as 

soon as possible.

Response: The NRC staff notes the comment. However, the subject of this comment is 

out of the scope of the NUREG.

Comment 7: Emmanuela Raquelle

ER-1 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

Comment 8: Jill ZamEk

I find the NRC analysis of nuclear waste transport inadequate and misleading for the following 

reasons:

JZ-1 The only NRC approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 100, which is not approved for high burn up fuel transport. Most of the 
10-15

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

JZ-2 The NRC has once again failed to address the core problem involving transportation of 

highly radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to 

a transport cask; however, the fragile, thick canisters that are being used at most nuclear 

facilities may likely be leaking radiation at the time of transfer, making transfer itself a potentially 

lethal undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

JZ-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

Comment 9: Erik Layman

EL-1 The only NRC- approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI-STAR 100, which is not approved for high burnup fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 
10-16

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

EL-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

EL-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the risk in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

EL-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 10: Meredith Angwin

The NRC has performed a careful analysis of real and theoretical rail accidents. The NRC has 

reached the correct conclusion that it is safe to transfer spent fuel by rail, in designed transfer 

casks.

I agree with this conclusion. Many hazardous materials are shipped by rail: but ONLY nuclear 

materials are shipped in such expensive and well-tested containers. Spent fuel shipping in 

designed casks is safe, and the casks have been tested, repeatedly, as fire and explosion safe. 

I personally wish that industrial chemicals would be equally as safely shipped! (There's a 

plywood factory about twenty miles from my house, and it is supplied by a rail line).
10-17

I have toured French nuclear facilities, and was surprised to find that they do not let spent fuel 

cool in on-site fuel pools for more than about two years. At that point, the fuel is taken out of the 

pools and shipped to· a central facility, where it is held in a giant fuel pool. When the fuel is 

shipped, it is still physically hot. In this blog post about my visit to France, you can see the 

porcupine-like fuel shipment casks, with their porcupine bristles that dissipate heat.

http://yesvy.blogspot.com/2011/06/manufacturing-and-fuel-cycle-in-france.html#.Vvf4wTam73E

American fuel is much cooler. American and French casks are designed to protect the fuel from 

fire and accident. American casks are not required to also cool fuel. However, the French 

system works safely, and has been safe for decades. So does the American system.

The NRC has done an admirable job of ensuring all types of nuclear safety, including rail safety. 

I agree with this conclusion in the NUREG/CR-7209 document abstract: "The combined 

summary of this work on fire accidents demonstrates that current U.S. Nuclear Regulatory 

Commission regulations and packaging standards provide a high degree of protection to the 

public health and safety against releases of radioactive material in real-world transportation 

accidents, were such events to involve SNF containers."

Approve the current standards, and do not waste tax payer’s money on endless and useless 

"improvements." If it ain't broke, you can test it (as you have). But if it ain't broke, and it passes 

the tests...don't "fix" it.

Response: The NRC staff notes the comment.

Comment 11: Linda Seeley (San Luis Obispo Mothers for Peace)

LS-1 The proposed NUREG/CR-7209 paints a rosy picture of the safety of transporting high 

level radioactive waste on the highways and railways of our country. It proposes transporting 

HOLTEC HI-STAR 100 SNF canisters on specially designed railroad cars.

The report makes false assumptions. It makes no provision for moving the SNF from existing 

thin-walled stainless steel canisters (1/2" to 5/8" thick) that cannot be inspected, repaired, 

maintained, have no early warning system prior to a radiation leak, can corrode and crack, and 

can start leaking millions of curies of radiation after 20 years of storage, possibly sooner, into 

the transport cask.

Response: NUREG/CR-7209 is a compendium (compilation summary) that summarizes 

analyses of simulated case studies of accident scenarios. Specifically, the scope of the 

analyses was on the thermal effects on the transportation package from severe fires; the scope 

did not include loading of spent fuel. In addition, refer to NRC’s response to DH-1 in Comment 

5.

LS-2 A 2015 Sandia Lab report shows that once cracks start in hotter thin-walled stainless 

steel canisters, they can grow through the wall of the canister in less than 5 years. A failure of 

even one of these "Chernobyl" canisters could be catastrophic. There is potential for 

explosions, due to the unstable and pyrophoric nature of these materials when exposed to air. 

(Damaged Spent Nuclear Fuel at U.S. DOE Facilities, Experience and Lessons Learned, INL, 

Nov 2005 INL/EXT-05-00760, Page 4 & 5). https://inldigitallibrary.inl.gov/sti/3396549.pdf
10-18

Response: NUREG/CR-7209 is a compendium (compilation summary) that summarizes 

analyses of simulated case studies of accident scenarios. Specifically, the scope of the 

analyses was on the thermal effects on the transportation package from severe fires.

LS-3 NRC regulations do not allow the transportation of canisters with even partial cracks 

(10 CFR § 71.85 Packaging and Transportation of Radioactive Materials). Neither the outside 

or inside structure of these thin-walled welded canisters can be inspected, let alone repaired. 

Other countries use thick-walled casks that do not have these problems.

Response: 10 CFR 71.85(a) states, “The certificate holder shall ascertain that there are no 

cracks, pinholes, uncontrolled voids, or other defects that could significantly reduce the 

effectiveness of the packaging.”

LS-4 NRC has chosen to continue endorsing the inferior technology even though NRC 

Commissioners directed staff to "encourage the adoption of state of the art technology for 

storage and transportation". Staff Requirements - COMDEK-09-0001 - Revisiting the Paradigm 

for Spent Fuel Storage and Transportation Regulatory Programs, February 18, 2010. 

http://pbadupws.nrc.gov/docs/ML1004/ML100491511.pdf

Response: NUREG/CR-7209 is a compendium (compilation summary) that summarizes 

analyses of simulated case studies of accident scenarios. Specifically, the scope of the 

analyses was on the thermal effects on the transportation package from severe fires.

LS-5 Canisters may need to stay on-site for up to 45 years before they are cool enough to 

meet Department of Transportation radiation dose requirements.

Thin-walled stainless steel U.S. irradiated spent fuel storage canisters at higher temperatures 

will have faster crack growth rate. A Sandia Lab chart shows higher temperatures can cause 

canisters to penetrate the wall in less than 5 years. This chart assumes canister wall is 0.625" 

(5/8") thick. The majority of the U.S. canisters are only 0.50" (1/2") thick. It is unknown when a 

crack will start, but these canisters are subject to corrosion and cracking from environmental 

conditions such as chloride salts, air pollution (sulfides), pitting, and microscopic scratches. The 

report states that canisters such as those at Diablo Canyon have temperatures in these heat 

ranges. Draft Geologic Disposal Requirements Basis for STAD Specification, A. llgen, C. 

Bryan, and E. Hardin, Sandia National Laboratories, March 25, 2015, FCRD-NFST-2013-

000723 SAND2015-2175R, PDF Page 46 http: 

Response: NUREG/CR-7209 is a compendium (compilation summary) that summarizes 

analyses of simulated case studies of accident scenarios. Specifically, the scope of the 

analyses was on the thermal effects on the transportation package from severe fires.

Note: The NRC staff determined that the link http: is not related 

to NUREG/CR-7209 and is therefore out of scope.

LS-6 The only NRC approved high burn up transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 100, which is not approved for high burnup fuel transport. Most irradiated 

spent fuel stored onsite at nuclear facilities can be classified as high burnup.

Response: NUREG/CR-7209 summarized the analysis of NUREG/CR-6886, which described 

the effects of the Baltimore tunnel fire scenario on the HI-STAR 100 transportation package. 
10-19

There was no postulation that the HI-STAR 100 would be used to transport high burnup fuel. In 

addition, refer to NRC’s response to JZ-1 in Comment 8.

LS-7 Canisters with 37 spent fuel assemblies may require up to 45 years to cool (after 

removal from the reactor) before they are safe enough to transport (-20 kW) per Dept. of 

Transportation radiation limits. Research and Development Activities Related to the Direct 

Disposal of Dual Purpose Canisters, William Boyle, Director, Office of Used Nuclear Fuel 

Disposition R&D (NE-53), U.S. Department of Energy, Nuclear Waste Technical Review Board 

Meeting, April 16, 2013.

http://www.nwtrb.gov/meetings/2013/april/boyle.pdf Safety Evaluation Report Docket No. 71-

9302, NUHOMS-MP197HB, Certificate of Compliance No. 9302, Rev. 7, Page 14 

http://pbadupws.nrc.gov/docs/ML1411/ML14114A132.pdf

NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. The thin-walled canisters storing the fuel rods are inadequate. In 

order to transport the canisters, the fuel rods will have to be transferred to a transport cask; 

however, the fragile, 1/2"thick canisters may likely be leaking radiation at the time of transfer, 

making transfer itself a potentially lethal undertaking.

Response: NUREG/CR-7209 is a compendium (compilation summary) that summarizes 

analyses of simulated case studies of accident scenarios. Specifically, the scope of the 

analyses was on the thermal effects on the transportation package from severe fires. In 

addition, refer to NRC’s response to DH-1 in Comment 5.

LS-8 Proposed NUREG/CR-7209 states that there has never been an incidence of Class B 

radioactive waste being mishandled during a shipment. NRC incident report from 

March 16, 2016 states, "The Agency [Texas Department of State Health Services] was notified 

by a manager for a common carrier of radioactive material that a package had fallen out of the 

transport vehicle. The package was found by a member of the public on a highway [when he] 

swerved to miss hitting the package. The person collected the package and called the number 

on the package. The number was to the manufacturer of the source. The radiation safety 

officer (RSO) for the company met the member of the public to collect the package. The RSO 

completed a survey of the package and performed leak testing. The container was a type B 

package containing two lr-192 sources, SN29629G and 29630G, joint activity of 8,188.8 Gbq 

(>100 curies each) with transport index of 1.2. The package outer shipping box was damaged 

although the type B container was in good condition and was not leaking. The sources are 

currently at the manufacturer's location in storage. The sources were on route to the 

manufacturer's Baton Rouge location when the container fell out of the transport vehicle onto 

the freeway. The details of the time frame the member of the public had the package in their 

possession is being confirmed and details of the time the package was on the freeway is being 

acquired. Investigation into this event is ongoing and details will be provided in accordance with 

SA 300 guidelines."

Response: Nowhere in NUREG/CR-7209 does it state that there has never been an incidence 

of Class B radioactive waste being mishandled during a shipment. NUREG/CR-7209 is focused 

on spent fuel content. It is noted that, based on the summary quoted above, the container 

transporting the two Ir-192 sources “was in good condition and not leaking” after the incident.

LS-9 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying to most people. With the rise in international terrorism, the targeting of nuclear 
10-20

power plants by ISIL, the oversized, slow-moving railway cars transporting nuclear waste might 

as well have bullseyes painted on them.

Highly radioactive spent fuel rods should not be moved more than once. There is no permanent 

repository for the waste now; Congress has yet to even designate a proper, safe location. To 

move the lethal waste not once, but TWICE, in order to continue to produce nuclear power, is 

unconscionable.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

Comment 12: Henriette Groot

HR-1 As we hear of more and more terrorist activity any transportation of highly radioactive 

waste material must be more carefully considered. Only transport casks that are approved by 

the NRC itself should be considered for transport of such waste.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

HR-2 Moving the highly radioactive waste should not be considered until a permanent storage 

place is found; moving it before such a place is found, i.e. moving it twice, would expose the 

public to great danger unnecessarily.

In view of the fact that a permanent is not yet found, and not likely to be found, the safest 

approach is to discontinue producing nuclear waste. Shut down and start decommissioning all 

nuclear power plants!

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 13: Gina Mori

I have said it once and I will say it again. Nuclear Energy has no place in the world. It is dirty, 

dangerous and deadly.

GM-1 Transporting nuclear waste is even more dangerous than the plants themselves. The 

variables involved in moving toxic, radioactive waste are many. Mother nature, human error 

and terrorism just to name a few, of the dangers.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

GM-2 We still have nowhere to store the toxic waste, so where would it be moved to? Yucca 

Mountain hasn't panned out and no one wants the waste in their backyard. Renewables are our 

future. It is time to decommission ALL remaining nuke plants.
10-21

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

GM-3 It is unconscionable to think that future generations will be burdened with toxic nuclear 

waste, for thousands of years.

Who will be accountable when the next nuclear disaster occurs? It is terrifying enough to know 

the nuke plants are vulnerable. The thought of radioactive waste traveling around by rail and 

road is petrifying. Rail travel has proven not to be safe. Whether it's a passenger train or a 

cargo train, derailments are far too common.

People must be put before profit. You have no right to continue to put the world at risk, with this 

deadly energy. Especially since renewables are safer and cheaper. No NUKES!!!!

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 14: Rosemary and Cal Wilvert

RCW-1 NRC has once again failed to address the core problem involving transportation of 

highly radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred 

to a transport cask; however, the fragile, thick canisters that are being used at most nuclear 

facilities may likely be leaking radiation at the time of transfer, making transfer itself a potentially 

lethal undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulation include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

RCW-2 The potential for terrorism with regard to transportation of highly radioactive nuclear 

fuel is terrifying. With the risk in international terrorism and the targeting of nuclear power plants 

by ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's 

eyes painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal 

targets for terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

RCW-3 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.
10-22

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 15: Ron Rattner

RR-1 The only NRC- approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 100, which is not approved for high burnup fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

RR-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

RR-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the risk in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

RR-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.
10-23

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 16: Simone Malboeuf

SM-1 The only NRC- approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 100, which is not approved for high burnup fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

SM-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

SM-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the risk in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

SM-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 
10-24

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

There really is no real logical and sane answer to the terrible issue of what to do with the highly 

radioactive waste that keeps multiplying over and over in hundreds of sites not only in the US, 

but all over the earth. No responsible adult would vote to continue to make this poison for future 

generations to be burdened with. WE MUST STOP MAKING IT NOW.

Moving this toxic radioactive waste around makes no sense. It is immoral to dump it into the 

backyards of indigenous or other poor people who cannot defend their home lands. The burden 

of caring for it and the expense belongs to those who made it - the nuclear industry should be 

made to fund and monitor the product that they made so much money on. It's just the cost of 

their doing business. They made the profits - they pay the costs.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 17: Peggy Koteen

Please do not allow for removal of Spent Fuel Rods from Diablo Nuclear Facility. Transporting 

high-level nuclear waste over the highways and railways is not safe for the public. This nuclear· 

waste was made in San Luis Obispo, and it needs to stay here. Thank you for your time.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 18: Barbara Scott

How can anyone possibly pronounce that spent fuel is safe at any time? We certainly have 

experienced disasters at nuclear power plants. To add the fragility involved in transporting that 

waste makes it more dangerous. Please do not even consider that possibility.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 19: Carl Holder

The NRC ensures all types of nuclear safety, including rail safety. I agree with the conclusion in 

the NUREG/CR-7209 document abstract:

"The combined summary of this work on fire accidents demonstrates that current U.S. Nuclear 

Regulatory Commission regulations and packaging standards provide a high degree of 

protection to the public health and safety against releases of radioactive material in real-world 

transportation accidents, were such events to involve SNF containers."

PUBLIC COMMENT: Spent nuclear fuel can be transported safely. Nuclear materials are 

routinely transported safely. Spent nuclear fuel is no different. Casks are hugely overengineered. Please allow the transportation of spent nuclear fuel.

Response: The NRC staff notes the comment.
10-25

Comment 20: Anonymous Anonymous 1

AA-1 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

AA-2 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the risk in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

AA-3 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 21: Eric Greening

EG-1 Thank you for this opportunity. The transportation of dangerous radioactive waste from 

Diablo Canyon raises a host of issues. If they were to be shipped by rail, they would need to be 

taken to a loading facility that does not now exist, by way of two-lane roads that pass through 

populated areas, then by way of Highway 101, and then presumably by way of the streets of 

San Luis Obispo or some other Central Coast city.

Once loaded on trains, these lethal loads would be sharing tracks with dangerous and explosive 

chemicals, including oil and petrochemicals. The amount of oil shipped on American tracks 

increased 40-fold between 2008 and 2014. To see a list of recent North American rail disasters 

involving these materials, visit the Final EIR on the Phillips 66 project proposed in San Luis 

Obispo County, turning to the section that includes public comments on the Draft, then to the 

category of "Organizations and Individuals," and then to the comments of "Mesa Refinery 
10-26

Watch," where you will find this list in the section on Hazards and Hazardous Materials. More 

such accidents have occurred since this correspondence was written.

The significance of the above is that these cargoes, which could potentially collide with, or derail 

in proximity to, trains carrying lethal radioactive waste, tend to react EXPLOSIVELY to collisions 

and derailments. The resultant fireballs can scatter whatever is involved in these accidents over 

large areas, and the smoke could become a vehicle for radioactive fallout. The concerns over 

accidents entangling radioactive with explosive cargoes only add to the many other concerns 

involved with radioactive waste transport, from human error to terrorism. Remember that our 

rails travel through the heart of most of the populated areas of our country, as well as traversing 

agricultural and wild areas that need to be kept clean.

Response: The NRC staff notes the comment. In addition, refer to Response RB-5 in Comment 

#2.

EG-2 While indefinite storage onsite raises many concerns of its own, if monitored and 

retrievable for repacking when containers leak, it raises fewer concerns than transport, in which 

accidents can happen faster than anyone can anticipate, and can overwhelm the capabilities of 

most emergency responders along the routes involved. To sum up, it is a dangerous and 

irresponsible idea!!

Response: The NRC staff notes the comment.

Comment 22: Lucy Jane Swanson

LJS-1 The only NRC- approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 100, which is not approved for high burnup fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

LJS-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”
10-27

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

LJS-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the risk in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

LJS-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 23: Anonymous Anonymous 2

AA-1 ap interresults 2016 and ts interresults 2016.

Check here http: 

Response: The NRC staff determined that the link http: is not related 

to NUREG/CR-7209 and is therefore out of scope.

Comment 24: Peg Pinard

PP-1 First of all, this report is very disturbing ... not because of what it says, but for what it 

doesn't say. It reminds me of a conversation I had with the NRC representatives when I was a 

San Luis Obispo County Supervisor and the new dry cast storage facility was being proposed 

for the Diablo Canyon Nuclear Power Plant (which was in my district).

When we were discussing the proposed containers, I asked if they were the "safest" ones? The 

NRC representatives replied: "To design that would be cost prohibitive." I then asked if the 

proposed containers were the safest ones "available"; meaning the safest ones "on the 

market"? To which they carefully said that the containers met NRC standards.

In other words, no.

We are hearing unprecedented public anger in this election year. Invariably, it comes down to 

the profound distrust people have of large corporations and big government. The Nuclear 

Regulatory Commission is "government" in action. The, NRC is supposed to be there to protect 

citizens from the potential safety compromises that profit-driven corporations may engage in. 

And what is unique about the responsibilities of this particular agency is that the ramifications 

aren't for incidents like a BP oil spill, or even an Exxon Valdez. Potential nuclear accidents are 
10-28

a matter of life and death ... the real lives of real people. Besides the possibility for direct 

personal contamination, nuclear accidents can render huge swaths of our precious land 

uninhabitable.

Words like "good" - as in the draft's sentence "using typical good practice standards" - leads one 

to wonder why can't we reflect the "best" in our standards? Why is it ok to meet only "good" 

standards? There's even more word-smithing, for instance ... "this code is widely used in the 

industry" and "occurs with extremely low frequency."

Fukushima's reports said all that too.

"Spent nuclear fuel" ... a term reminiscent of an oil change, is another euphemism meant to 

keep the public from being too concerned about the dangers of the high level radioactive waste 

that is actually being transported or stored near them.

Response: The phrases “using typical good practice standards” (NUREG/CR-7209, page 4-2), 

“this code is widely used in the industry” (page 4-3), and “occurs with extremely low frequency” 

(page 3-6), are relevant descriptions and standard language. “Spent nuclear fuel” is defined by 

regulations in 10 CFR 71.4, “Definitions.” The staff has made no changes in the draft as a result 

of this comment.

PP-2 The most egregious example of avoiding relevant data and the NRC's deliberate 

manipulation is the report's selection of rail accident years. 1997-2008. This is 2016!

The selection of these particular years avoids having to account for, or take into consideration, 

the many rail accidents that have happened since oil became such a huge rail transport 

business. This document is supposed to be a current report and yet the latest data is from 

2008? Heck, even the survey for NRC website users is dated 2016! And you wonder why 

people mistrust government?

Response: NUREG/CR-7209 is a compendium (compilation summary) of analyses that NRC 

previously published. The survey of railway accidents described in Section 3.1 of NUREG/CR7209 refers to an analysis published in NUREG/CR-7034 (2011) that reflects the railway 

accident statistics for the period described in that publication.

PP-3 There's information about "burn rates" and "fire spread charts" but nothing about the 

condition of the rails and the aged facilities expected to carry the weight loads of this high level 

radioactive waste. According to industry sources, the average age of all U.S. freight rail cars 

was between 20 to 24.5 years. Ironically, this NRC report comments that: "As the train was 

passing through the tunnel, 11 of the 60 rail cars derailed." The age of the tracks, the fact that 

many locations have only single tracks, and the cars themselves should be a source of great 

concern in the safety analysis.

Response: NUREG/CR-7209 is a compendium (compilation summary) that summarizes 

analyses of simulated case studies of accident scenarios. Specifically, the scope of the 

analyses was on the thermal effects from severe fires on transportation packages; the scope did 

not include conditions of rail or rail facilities.

The U.S. Department of Transportation has the statutory authority under the Hazardous 

Materials Transportation Act to regulate the transportation of hazardous materials by all modes, 

including rail, roadway, air, and water vessel. Comments about the condition of rail and rail 

facilities should be sent to the following address:
10-29

Office of Hazardous Materials Safety

Pipeline and Hazardous Materials Safety Administration

U.S. Department of Transportation

1200 New Jersey Avenue, SE

Washington, D.C. 20590-0001

PP-4 I think the public wants to see analyses reflecting "this is the best practice" for safety on 

our rails. Where nuclear safety is concerned "good enough", "not cost effective", or just "meets 

our standards" are not reassuring words. While I can appreciate the fact that the NRC is finally 

examining the safety of rail transport, it is imperative that it be done with eyes wide open, drop 

the word-smithing and include all the current data. This high level radioactive waste is going 

through our densely populated cities and family neighborhoods often within feet of our homes 

and businesses. Because of the severity of the consequences of any accident, the NRC has 

the responsibility and moral obligation to all Americans for being thorough in its analysis and for 

providing for BEST safety practices! "Trust" is something that needs to be earned.

Response: The NRC staff notes the comment.

Comment 25: Anonymous Anonymous 3

AA-1 The only NRC approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 100, which is not approved for high burnup fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

AA-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”
10-30

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

AA-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

AA-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 26: Kelly Reed

KR-1 The NRC has once again failed to address the core problem involving transportation of 

highly radioactive used fuel rods. In order.to transport, the fuel rods will have to be transferred to 

a transport cask; however, the fragile, thick canisters that are being used at most nuclear 

facilities may likely be leaking radiation at the time of transfer, making transfer itself a potentially 

lethal undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

KR-2 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).
10-31

KR-3 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 27: Anonymous Anonymous 4

AA-1 The NRC has prepared a document, “A Compendium of Spent Fuel Transportation 

Package Response Analyses to Severe Fire Accident Scenarios; Draft NUREG/CR-7209; 

Request for Comment. The analysis in the document basically says

The only NRC approved high burnup transport cask is the NUHOMS MP197HB. NUREG/CR7209 postulates that highly radioactive spent fuel rods will be transported using the HOLTEC HISTAR 100, which is not approved for high burnup fuel transport. Most of the irradiated spent 

fuel stored onsite at nuclear facilities can be classified as high burnup. High burnup fuel may 

need as long as 45 years in storage before it is deemed safe enough for transport.

Response: NUREG/CR-7209 is a compilation summary of analyses from four severe fire 

accident scenarios that were previously published. The Baltimore tunnel fire scenario, which 

analyzed the thermal response of the HI-STAR 100 package to the severe fire accident 

scenarios, was published in 2009. The Baltimore tunnel fire analysis conservatively assumed 

100 percent failure of fuel rods during an accident to predict potential consequences, per NRC 

guidance. This guidance applies to both high-burnup and low-burnup fuel.

AA-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, ”thick” canisters that are being used at most nuclear 

facilities may likely be leaking radiation at the time of transfer, making transfer itself a potentially 

lethal undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

AA-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).
10-32

AA-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 28: Kathleen Oliver

KO-1 This compendium did NOT address the core problem involving transportation of highly 

radioactive used fuel rods. That problem is: In order to transport, the fuel rods will have to be 

transferred to a transport cask; however, the fragile, thick canisters that are being used at most 

nuclear facilities are likely be leaking radiation at the time of transfer, making transfer itself a 

potentially lethal undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

KO-2 Also, the potential for becoming terrorism targets while transporting highly radioactive 

nuclear fuel is terrifying. With the rise in international terrorism and the targeting of nuclear 

power plants by ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well 

have bull's eyes painted on them. These trucks and trains will be slow-moving, vulnerable, and 

lethal targets for terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

Comment 29: Abram Perlstein 

AP-1 The only NRC approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 100, which is not approved for high burn up fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 
10-33

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

AP-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

AP-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

AP-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 30: Jean’ne Blackwell

JB-1 There is no place to safely store spent fuel. There is no place to safely store spent fuel. 

There is no place to safely store spent fuel. A person with an ounce of common sense must 

realize that we are imperfect human beings and fallible. We make mistakes. Accidents happen. 

So in good conscience you cannot sign onto this report. You know in your heart you are risking 

the safety, health and wellbeing for generations to come.

Please let your heart be your guide. It is really the only that can insure a decision that will serve 

humanity in the best possible way and something you can be very proud of.

Response: The NRC staff notes the comment.
10-34

Comment 31: Robert Fronczak (Association of American Railroads)

Attached are the Association of American Railroads comments to Draft NUREG/CR-7209 report 

entitled, "A Compendium of Spent Fuel Transportation Package Response Analyses to Severe 

Fire Accident Scenarios."·

2016-3-28 AAR Comments on NUREG-CR-7209 PNNL-24 792 NRC Fire Study Final.

RF-1 The Association of American Railroads ("AAR"), on behalf of itself and its member 

railroads, submits the following comments to the Nuclear Regulatory Commission's report 

entitled "A Compendium of Spent Nuclear Fuel Transportation Package Response Analysis to 

Severe Fire Accident Scenarios". (NUREG/CR-7209)1

. The U.S. Department of Energy ("DOE") 

has stated that rail is the preferred' mode of transportation of spent nuclear fuel ("SNF"), giving, 

AAR and its member railroads a major interest in its safe transportation. The conclusions 

reached in the report are flawed because the time period NRC used to evaluate railway 

accidents involving fire was limited to 1997 - 2008. By limiting the time period of railway 

accidents in the report, the report fails to capture several major changes in the transportation of 

hazardous materials in North America in the early 21st Century.

1 AAR is a trade association whose membership includes freight railroads that operate 72 percent of the 

line-haul mileage, employ 92 percent of the workers, and account for 95 percent of the freight revenues of 

all railroads in the United States; and passenger railroads that operate intercity passenger trains and 

provide commuter rail service.
10-35

Response: NUREG/CR-7209 is a compilation summary of analyses that NRC previously 

published. The survey of railway accidents described in Section 3.1 of NUREG/CR-7209 refers 

to an analysis published in NUREG/CR-7034 (2011) that reflects the railway accident statistics 

for the period described in that publication. In addition, although the case studies analyzed in 

NUREG/CR-7209 do not include accidents after 2007, the results of the analyses showed that 

the transportation packages designed to meet 10 CFR Part 71, “Packaging and Transportation 

of Radioactive Material,” regulations are robust to survive fire accidents more severe than the 

conditions defined in 10 CFR 71.73(c)(4). However, the four case studies described in 

NUREG/CR-7209 do not necessarily represent all severe fire scenarios, such as those listed in 

your letter.

RF-2 The early 2000's saw a large increase in the transportation of ethanol. Additionally, 

there has been an even larger increase in the number of petroleum crude oil shipments starting 

in around 2009. In 2014, petroleum crude oil became the largest and ethanol was the second 

largest hazardous material transported by rail. Ethanol and petroleum crude oil are transported 

in large blocks of tank cars and/or unit trains, which is different than the historic practice of a 

smaller number of shipments of flammable liquids. Figure 1 shows how petroleum crude oil 

moves by rail.

Figure 1 - How Petroleum Crude Oil Moves by Rail

Source: AAR, Third Quarter2015 Data

Table 1 shows the annual number of petroleum crude oil shipments in the US from 2008 to 

2014. The number of carloads of petroleum crude oil has increased by over 5,683% since 

2009.
10-36

Table 1

Number of Annual Carloads of Petroleum Crude Oil Terminated in the US

2008-2014

Unfortunately, the number of accidents involving large quantities of ethanol and petroleum crude 

oil has increased, even though the train accident rate is the lowest on record, due to the large 

increase in the number of shipments of these commodities. Table 2 is a list of the large 

flammable liquids derailments since 2006.

Table 2

Large crude oil and ethanol derailments since 2006
10-37

Fires are likely to occur when ethanol or petroleum crude oil is released in a derailment. The 

U.S. Department of Transportation ("DOT")'s regulatory impact analysis on the HM-251 

rulemaking stated that "the properties of the flammable liquids and handling of the cars in large 

blocks or unit trains presents a unique hazard in that, if released and ignited, the fire will affect 

adjacent cars."2 Historically, non-jacketed DOT-111 tank cars were used for the transportation 

of petroleum crude oil and ethanol. Non-jacketed DOT-111 tank cars do not have a thermal 

protective blanket, which reduces the conductance of heat into the tank car. As cars heat up in 

pool fires started by impact caused releases, the pressure in adjacent cars increases until it 

reaches the pressure relief device setting, at which time the valves opens and feeds more fuel 

to the fire. As the level in the cars drops, the steel on the top of the cars heats up rapidly, 

weakening the steel at the top of the car. When the temperature reaches a crucial point, the 

tank car material fails. Failure occurs either by a thermal tear, which occurs at the top of the car 

to release pressure, or catastrophically with the car breaking into pieces. In both cases, the 

entire contents of the car is released and further contributes to the fire.

An estimated 1.5 million gallons of petroleum crude oil was released in the horrific July 6, 2013 

accident in Lac-Megantic, Quebec. The fire burned for over 28 hours and reached upwards of 

1,800 'F as evidence by eye witness reports that some of the steel of the tank cars involved 

actually melted. ·The Transportation Safety Board of Canada's report on the Lac-Megantic 

accident indicated that "thirteen tank cars had localized loss of tank material in the form of a 

bum through as a result of extreme fire damage." 3,4 The fire in the Lac-Megantic derailment 

was not extinguished until 11:00 on July 7, 2013 with only minor flare-ups after that point in 

time.5 The fire caused by the Lac-Megantic accident was extremely hot and lasted for an 

extended time period.

2 Docket No. PHMSA-2012-0082] (HM-251) - Hazardous Materials: Enhanced Tank Car Standards and 

Operational Controls for High-Hazard Flammable Trains; Final Rule, Office of Hazardous Material Safety, 

May 2015.

3 A bum-through is a perforation of the tank shell caused by fire damage. 

http://www.tsb.gc.ca/eng/rapports-reports/rail/2013/r13d0054/r13d0054.pdf, Page 47

4 http://www.tsb.gc.ca/eng/rapports-reports/rail/2013/r13d0054/r13d0054.pdf, Page 47

5 http://www.tsb.gc.ca/eng/rapports-reports/rail/2013/r13d0054/r13d0054.pdf, Page 47

Response: NRC notes the information presented in this comment.

RF-3 NRC should have also included a number of additional accidents involving the 

transportation of ethanol and petroleum crude oil by rail in its analysis. Since 2008, there have 

been a number of high-profile derailments involving these products, including: the 2009 accident 

in Cherry Valley, IL; the 2011 accident. In Tiskilwa, IL; the 2012 accident in Columbus, OH; the 

2013 accident in Casselton, ND; the 2014-accident in Lynchburg, VA; and the 2015 accident in 

Mt. Carbon, WY. Please see the appendix to these comments for URLs to the National 

Transportation Safety Board (''NTSB") accident reports or dockets.

NRC should have included these accidents involving fires caused by the rail transportation of 

ethanol and petroleum crude oil because it would provide for a more accurate analysis of the 

inherent challenges in the transportation of these commodities.

Response: The results of the analyses in NUREG/CR-7209 show that the transportation

packages designed to meet 10 CFR Part 71, “Packaging and Transportation of Radioactive 
10-38

Material,” regulations are robust to survive fire accidents more severe than the conditions in 

10 CFR 71.73(c)(4). The four case studies described in NUREG/CR-7209 do not necessarily 

represent all severe fire scenarios, such as those listed in your letter. However, as mentioned 

on page 1-1 and page 3-6 of NUREG/CR-7209, the safe transport of spent nuclear fuel is a 

function of package design and administrative controls associated with transport. The 

information about the statistics and incidents related to large transports of ethanol and 

petroleum crude oil presented by AAR indicates the importance of administrative controls to 

address the possibilities associated with transporting spent nuclear fuel by rail where large 

quantities of ethanol and petroleum crude oil are also transported. This is an area where 

relevant governing authorities for safe rail transport of hazardous material, rail transport 

stakeholders who have intimate knowledge of rail transport (such as AAR), and owners of spent 

fuel from storage sites can determine the specific rail operation measures necessary for safe 

transportation.

RF-4 Mitigating Factors

NRC notes that several mitigating factors make the chance of a SNF cask being involved in fire 

less likely. One mitigating factor is that DOE plans to ship SNF by rail in dedicated trains. A 

SNF train could be involved in an accident involving a release of flammable liquids and a 

resulting fire if it happened to be passing another train with flammable liquids that derailed. 

While unlikely, the derailment at Casselton, ND in December of 2013 is proof that such a 

scenario can occur and result in a major fire in this case involving 400,000 gallons of petroleum 

crude.

Another mitigating factor is DOT's final rule HM-251 - Enhanced Tank Car Standards and 

Operational Controls for High-Hazard Flammable Trains ("HM- 251")6

. HM-251 requires 

flammable liquid tank cars to either be retrofitted to higher standards or be replaced with new 

tank cars meeting the new DOT-117 standard. HM-251 will reduce the conditional probability of 

a release ("CPR") in a derailment of a DOT-117 car significantly over a non-jacketed DOT-111 

tank car by ensuring a stronger tank car to transport flammable liquids with a thicker shell, a 

jacket, head shields, top and bottom fitting protection and thermal protection.

Table 3 below shows the CPRs for the jacketed and non-jacketed legacy DOT-111, CPC-1232 

and DOT-117 cars.7 The CPR for releases of more than 100 gallons is shown as well as the 

overall CPR since minor leaks are not the concern addressed by the HM-251 rulemaking.

Table 3.
10-39

The 2015 FAST Act requires DOT to further mandate improved tank car survivability in 

accidents by delineating a prioritized phase-out schedule.9 Non-jacketed DOT-111 tank cars 

carrying petroleum crude oil must be phased out/retrofitted first by January 1, 2018. Nonjacketed DOT-111's carrying ethanol have to be phased out/retrofitted by May 1, 2023. Finally, 

all other non-DOT-117 tank cars carrying flammable liquids have to be phased out/retrofitted by 

May 1, 2029. The FAST Act also requires the thermal protection requirement to be changed to 

a minimum 1⁄2” thermal blanket. As a result of these changes, tank cars carrying petroleum 

crude oil and ethanol, the products most often carried in large blocks or unit trains, will be 

transported in more crash resistant tank cars the soonest. In addition, the thermal blanket 

requirement will greatly reduce the chance these cars, when involved in a derailment and fire, 

will sustain a thermal tear or catastrophic failure.

In summary, NRC should update its report titled "A Compendium of Spent Nuclear Fuel 

Transportation Package Response Analysis to Severe Fire Accident Scenarios," to include more 

recent accidents reflecting the large increase in energy products by rail in the US, and NRC 

should take into consideration the mitigating factors associated with the reduced risk of 

transporting these products as required by HM-251 and supplemented by the FAST Act.

AAR and its member railroads are committed to the safe, secure and efficient transportation of 

hazardous materials, and look forward to NRC's response to these comments.

6 80 Federal Register, No, 89, May 8, 2015.

7 CPC-1232 issued on August 31, 2011 is an AAR interchange rule implemented by the AAR Tank Car 

Committee for tank cars carrying packing group I and II petroleum crude, alcohols NOS and ethanol and 

gasoline mixture commodities constructed after October 1, 2011 to be upgraded, prior to DOT final action 

in May of 2015.

8 The CPRs in this table are significantly lower than the CPRs published in the RSI-AAR Project's Report 

RA-05-02, "Safety Performance of Tank Cars in Accidents: Probabilities of Lading Loss," (January 2006). 

For example, the recalculated CPR for the current DOT-111 tank car without a jacket is 25 percent lower 

than was calculated in 2006. There are three reasons. One, RA-05-02 used data from accidents that 

occurred from 1965-1997. The CPRs in Table 3 are based on more recent data, from 1980-2010. More 

recent data are more likely to be representative of accidents occurring today. Two, Table 3 CPRs were 

calculated utilizing more factors than were used in RA-05-02, including train speed, derailment severity, 

tank diameter, and commodity transported. Three, the techniques used for the newer analysis allowed for 

better handling of some of the complexities of the data that could have masked important relationships in 

the RA-05-02 analysis.

9 https://www.congress.gov/114/bills/hr22/BILLS-114hr22enr.pdf

Response: The NRC staff notes the information presented in this comment.

Comment 32: Carole Anonymous

CA-1 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.
10-40

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

CA-2 Furthermore, NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be 

transported using the HOLTEC HI STAR 100, which is not approved for high burnup fuel 

transport. Most of the irradiated spent fuel stored onsite at nuclear facilities can be classified as 

high burnup. High burnup fuel may need as long as 45 years in storage before it is deemed 

safe enough for transport.

Response: NUREG/CR-7209 is a compilation summary of analyses from four severe fire 

accident scenarios that were previously published. The analyses conservatively assumed 100 

percent failure of fuel rods during an accident to predict potential consequences, per NRC 

guidance. This guidance applies to both high-burnup and low-burnup fuel.

CA-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

CA-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 33: Franklin Frank

FF-1 I was unaware of this analyses until today therefore my comments will be brief. As a 

former County Fire Chief responsible for emergency actions at the Diablo Canyon Nuclear 

Power Plant, I served on a County Committee to investigate the transport of nuclear waste.

We studied the issue for several years, interviewing authorities on the subject, reading NRC and 

other documents, as well as, attending lectures on the matter. Our final conclusions were that 

the NRC regulations with respect to transport cast design were inadequate and that transport of 

casks through populated areas was too risky.
10-41

While your study focus is fire related and concludes that the probability of a release of 

radioactive isotopes is very low, it fails to consider terrorism. The possibility of terrorist attack 

was the primary reason our committee concluded that transport of nuclear was far too risky, it is 

essential that your study include terrorist attack in your analyses. Thank you for the opportunity 

to comment on this important issue.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

Comment 34: Elizabeth Brousse

EB-1 The NRC has once again failed to address the core problem involving transportation of

highly radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred 

to a transport cask. Here is the problem. The fragile,1/2" thick canisters tp.at are being used at 

most nuclear facilities may be leaking radiation at the time of transfer, thus making transfer itself 

a potentially lethal undertaking. 

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

EB-2 Add to this the absence of a permanent storage facility and the potential for terrorism 

during transport you have a lethal scenario before you. Please reject this proposal.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

Comment 35: Gary Kirkland

GK-1 People who make decisions based on fear of danger are cowards. People should make 

important decisions based on reason. The valiant do things despite the dangers. Americans are 

brave and do things in spite of the dangers. Radiation is everywhere I observe in this universe. 

The center of the earth all the way to the crust is hot because of radioactive decay. Uranium 

and other elements decay producing heat. Outer space is highly radioactive because of solar 

winds. Rocks and bricks have radioactive decaying elements in them. Radiation causes 

mutations in deoxyribonucleic acid (DNA). This drives evolution. Background radiation is 

responsible for most mutations. How does one get away from background radiation? Leave the 

universe?

Transport of nuclear waste will not increase background radiation by a measurable amount. 

Don't fear nuclear waste. It is a part of life. Be brave.

Response: The NRC staff notes the comment.
10-42

Comment 36: Romola Georgia

RG-1 The only NRC approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI-STAR 100, which is not approved for high bum up fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

RG-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

RG-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

RG-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.
10-43

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 37: Betty Winholtz

BW-1 Transporting high-level nuclear waste over the highways and railways is unsafe and 

vulnerable to fires, no matter what the circumstances. Look at what's been happening with coal 

trains.

Response: The NRC staff notes the comment.

Comment 38: Anonymous Anonymous 5

AA-1 I strongly disagree with your "Compendium" document which essentially says that 

transporting high-level nuclear waste over the highways and railways is safe and invulnerable to 

fires, no matter what the circumstances.

Response: The NRC staff notes the comment.

AA-2 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants, 

the oversized trucks and trains transporting nuclear fuel rods will be slow-moving, vulnerable 

and lethal targets for terrorist groups.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

AA-3 NRC has once again failed to address another problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask. However, the fragile thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

AA-4 Additionally, the transport cask which will be used has not been approved for high 

burnup fuel transport and most of the irradiated spent fuel stored at nuclear facilities can be 

classified as high burnup.

Response: NUREG/CR-7209 is a compilation summary of analyses from four severe fire 

accident scenarios that were previously published. The analyses conservatively assumed 100 
10-44

percent failure of fuel rods during an accident to predict potential consequences, per NRC 

guidance. This guidance applies to both high-burnup and low-burnup fuel.

AA-5 There is no permanent repository for nuclear waste and no safe location has been 

designated for the disposition of radioactive materials. Since highly radioactive spent fuel rods 

should not be moved more than once, moving this lethal waste now would require a second 

move. Moving this lethal waste not once, but twice, in order to continue to produce nuclear 

power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

AA-6 I urge the NRC to put an immediate stop to the idea of transport and focus instead on 

permanently closing down the Diablo Canyon Nuclear Power Plant and others around the U.S. I 

live every day with the concern that there will be a meltdown or release of radiation from the 

Diablo Canyon plant that will permanently affect not only my health and welfare but will render 

the agricultural lands that we need for food production non-productive and create vast 

wastelands of our current home environments.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 39: Don Andrade

DA-1 Although the bottom comment is consistent with my own feelings and thoughts about 

this, I will add that I live near a Nuclear power plant and have studied problematics related to 

spent waste for over 25-years and realize this problem is not going away, and that the only thing 

we can do is manage it well so far most policy or lack their-of do not address how to do this well 

in the USA. So keeping things put is part of the best solution. I say this even though our ponds 

at Diablo Canyon are just about full and it paces my own home of over 20-years in a sketchy 

situation. Please be realistic, and do not move these materials.

The only NRC approved high burnup transport cask is the NUHOMS MP197HB. NUREG/CR7209 postulates that highly radioactive spent fuel rods will be transported using the HOLTEC HI 

STAR 100, which is not approved for high burnup fuel transport. Most of the irradiated spent 

fuel stored onsite at nuclear facilities can be classified as high burnup. High burnup fuel may 

need as long as 45 years in storage before it is deemed safe enough for transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

DA-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 
10-45

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

DA-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

DA-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 40: Barbara Feild

BF-1 The only NRC approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 1-00, which is not approved for high burnup fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.

BF-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 
10-46

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

BF-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials.

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

BF-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 41: Janet Lester

JL-1 The only NRC approved high burnup transport cask is the NUHOMS MP197HB. 

NUREG/CR-7209 postulates that highly radioactive spent fuel rods will be transported using the 

HOLTEC HI STAR 1-00, which is not approved for high bum up fuel transport. Most of the 

irradiated spent fuel stored onsite at nuclear facilities can be classified as high burnup. High 

burnup fuel may need as long as 45 years in storage before it is deemed safe enough for 

transport.

Response: NUREG/CR-7209 is a compilation summary of accident analyses from four severe 

fire accident scenarios that were previously published. The Baltimore tunnel fire scenario, 

which analyzed the thermal response of the HI-STAR 100, TN-68, and NAC LWT packages to 

the severe fire accident scenarios, was published in 2009. The NUHOMS MP197HB was 

certified in 2014, years after the Baltimore tunnel fire analysis was published. The Baltimore 

tunnel fire analysis conservatively assumed 100 percent failure of fuel rods during an accident 

to predict potential consequences, per NRC guidance. This guidance applies to both highburnup and low-burnup fuel.
10-47

JL-2 NRC has once again failed to address the core problem involving transportation of highly 

radioactive used fuel rods. In order to transport, the fuel rods will have to be transferred to a 

transport cask; however, the fragile, thick canisters that are being used at most nuclear facilities 

may likely be leaking radiation at the time of transfer, making transfer itself a potentially lethal 

undertaking.

Response: The safe handling, storage, and transport of radioactive material must be performed 

according to regulations to satisfy established dose limitations. These regulations include the 

following:

• 49 CFR 173.441, “Radiation Level Limitations and Exclusive Use Provisions”

• 10 CFR 20, “Standards for Protection Against Radiation”

• 10 CFR 71, “Packaging and Transportation of Radioactive Material”

• 10 CFR 72, “Licensing Requirements for the Independent Storage of Spent Nuclear Fuel 

and High-Level Radioactive Waste, and Reactor- Related Greater Than Class C Waste”

JL-3 The potential for terrorism with regard to transportation of highly radioactive nuclear fuel 

is terrifying. With the rise in international terrorism and the targeting of nuclear power plants by 

ISIL, the oversized trucks and trains transporting nuclear fuel rods might as well have bull's eyes 

painted on them. These trucks and trains will be slow-moving, vulnerable, and lethal targets for 

terrorist groups who wish to do damage or to secure nuclear materials. 

Response: The NRC staff notes the comment. The transport of spent nuclear fuel follows 

security protocols and regulations (10 CFR 73.37, Requirements for Physical Protection of 

Irradiated Reactor Fuel in Transit).

JL-4 Highly radioactive spent fuel rods should not be moved more than once. There is no 

permanent repository for the waste now; Congress has yet to even designate a proper, safe 

location for disposition of radioactive materials. To move the lethal waste not once, but TWICE, 

in order to continue to produce nuclear power, is unconscionable.

Response: The NRC staff notes the comment, but the subject of the comment is out of the 

scope of this NUREG.

Comment 42: Robert Halstead (Agency for Nuclear Projects, State of Nevada)

State of Nevada Freedom of Information Act Request for Documents

Pursuant to the Freedom of Information Act ("FOIA"), 55 U.S.C. 552, legal counsel for the State 

of Nevada on March 21, 2016, requested that NRC provide all documents1 in its possession 

meeting the following descriptions, with respect to NUREG/CR-7209 ("A Compendium of Spent 

Fuel Transportation Package Response Analyses to Severe Fire Accident Scenarios"), whose 

preparation is referred to below as "the project":

1. All documents related to the history of "the project," including all documents discussing 

the initial decision to summarize studies of truck and rail transport accidents involving 

fires, relative to regulatory requirements for shipment of commercial spent nuclear fuel, 

the selection of the contractor, all communications to and from any potential or actual 

contractor, the original project schedule, or the actual start work date and conclusion;
10-48

2. All "documents and communications related to any direct involvement by members of 

the Commission in this project;

3. All documents related to or disclosing the total cost of, and/or budget details for, the 

project, including contractor costs and NRC staff costs;

4. All documents related to any peer review of the report by any person or entity, including 

selection of peer reviewers, cost of peer review, peer review comments; and/or 

resolution of any concerns raised during peer review; and

5. All documents related to or containing any comments by NRC staff members as part of 

the peer review, or NRC staff comments in addition to the peer review.

We appreciate the prompt reply by the NRC FOIA Officer, dated march 21, 2016, estimating 

that completion of our request would be on or before April 18, 2016. Completion by this date 

would facilitate further review and comment by our staff and contractors.

1 "Documents," in this regard, should be given the broadest possible interpretation, to include, without 

limitation, all electronic documents and hard copies, tapes, CD-ROMs, notes, letters, papers, books, 

reports, graphics, studies and files, together with any associated compilations.

RH-1 Inadequate Time for Public Review and Comment.

The 60-day comment period is inadequate. The scope of the report, and the technical 

complexity of the subject matter, justify a longer comment period of at least 90 days and, 

preferably, 120 days. Specific technical issues, such as the selection of shipping cask designs 

and fire accident scenarios for analysis, have required that our agency contract with an outside 

technical reviewer to assist us in preparing our comments. 

Please assist us in understanding how the original 60-day comment period was established by 

answering the following questions: 

- When did the concept for this project originate? 

- When did the contractors at Pacific Northwest National Laboratory begin work on this project? 

- When did the peer review occur, and how long was the peer review period?

- What efforts were made by NRC to solicit stakeholder comment on this project, prior to 

completion of the draft report in October 2015?

Response: NUREG/CR-7209 is a compendium that summarizes the previously published 

NUREG/CR-6886 (Baltimore tunnel fire scenario), NUREG/CR-6894 (Caldecott Tunnel fire 

scenario), NUREG/CR-7206 (MacArthur Maze fire scenario) and NUREG/CR-7207 (Newhall 

Pass fire scenario). Each of these four NUREG/CRs was open to public review and comment 

for up to 60 days. In addition, NUREG/CR-7209, which is a compilation summary of the 

previously published documents, was open to public review and comment for 60 days. 

Therefore, the 60-day period, which is within the guidelines for a public review and comment 

period, is believed to be adequate for NUREG/CR-7209.

- The concept for this project originated in 2013.

- The PNNL contractors began work on this project in 2014.

- NUREG/CR-7209 is a compilation summary of previously published NUREG/CRs; 

hence, there was no peer review.
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- As mentioned above, NRC efforts to solicit stakeholder comments on the material 

presented in NUREG/CR-7209 began years earlier with the publication of the individual 

NUREG/CRs. The notice for public comment on NUREG/CR-7209 was published in 

January 2016.

RH-2 Potential Implications of NUREG/CR-7209 for NRC Licensing Proceedings 

Finalization of Draft Report NUREG/CR-7209 could have significant implications for the 

evaluation of transportation impacts in future NRC licensing proceedings for interim storage 

facilities and geologic disposal facilities. NRC administrative law judges have already 

established the ground rules for evaluation of transportation impacts under the National 

Environmental Policy Act (NEPA) in the currently suspended licensing proceeding for the 

proposed Yucca Mountain repository:

Transportation of nuclear waste is a foreseeable consequence of constructing a nuclear waste 

repository. As California persuasively argues, “Without transportation of the waste to it, Yucca 

Mountain would be just a very large, fancy, and expensive hole in a mountain.” The 

Commission, for example, has stated that there can be “no serious dispute” that the NRC’s 

environmental analysis in connection with licensing nuclear facilities should extend to “related 

offsite construction projects – such as connecting roads and railroad spurs.” Likewise, there 

can be no serious dispute that the NRC’s NEPA responsibilities do not end at the boundaries of 

the proposed repository, but rather extend to the transportation of nuclear waste to the 

repository. The two are closely interdependent. Without the repository, waste would not be 

transported to Yucca Mountain. Without transportation of waste to it, construction of the 

repository would be irrational. Under NEPA, both must be considered.2

As part of the Yucca Mountain licensing process, NRC staff reviewed and adopted the 2008 

U.S. Department of Energy (DOE) Final Supplemental Environmental Impact Statement 

(FSEIS) for Yucca Mountain (DOE/EIS-0250F), including the transportation impact calculations 

for the mostly rail transportation scenario.3

As part of its finalization of Draft Report NUREG/CR-7209, NRC staff must assess the 

implications of the findings and conclusions of the Draft Report for the FSEIS transportation 

impact calculations adopted by NRC staff in the Yucca Mountain licensing proceeding. The 

DOE FSEIS adopted by NRC staff evaluated the consequences of release of radioactive 

material as a result of the maximum reasonably foreseeable transportation accident (probability 

about 5 in one million per year), involving a fully engulfing fire, 34 rem dose to the maximally 

exposed individual, 16,000 person-rem population dose and 9.4 latent cancer fatalities in an 

urban area, and cleanup-costs of $300,000 to $10 billion. [FSEIS, Pp.6-15, 6-24, G-56] 

2 NRC, Atomic Safety and Licensing Boards, Memorandum and Order Identifying Participants and 

Admitted Contentions, Docket NO. 63-001-HLW (May 11, 2009).

3 NRC, U.S: Nuclear Regulatory Commission Staffs Adoption Determination Report for the U.S. 

Department of Energy's Environmental Impact Statements for the Proposed Geologic Repository at 

Yucca Mountain, Pp. 3-13, 3-15, 5-1(September5, 2008).

Response: NUREG/CR-7209 is a compilation summary of previous analyses from four severe 

fire accident scenarios on transportation packages that were previously published; results of the 

analyses showed that potential releases were below regulations. In addition, NUREG/CR-7209 

does not present new policy or accident statistics. The information presented in 
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NUREG/CR-7209 does not have direct implications for the DOE document mentioned in the 

above comment.

RH-3 Potential Implications of NUREG/CR-7209 for Full-Scale Cask Testing

None of the spent fuel shipping casks currently used in the United States has been tested fullscale to confirm their performance in regulatory or extra-regulatory fire accident scenarios. 

NUREG/CR-7209 should make this fact clear to readers, and explain that none of the four casks 

evaluated (GA-4, HI-STAR 100, NAC-LWT, and TN-68) has been subjected to full-scale testing 

for any of the four hypothetical accident conditions (impact, fire, puncture, and immersion) set 

forth in 10 CFR Part 71.

In 2006, the National Academies (NAS) report, “Going the Distance?” endorsed full-scale testing 

of shipping casks under certain conditions. The Draft NUREG/CR-7209 cites this NAS report 

regarding fire accident scenarios, but does not address the NAS recommendations regarding 

full-scale cask testing. The NAS finding and recommendation are as follows: 

FINDING: The committee strongly endorses the use of full-scale testing to determine how 

packages will perform under both regulatory and credible extra-regulatory conditions. Package 

testing in the United States and many other countries is carried out using good engineering 

practices that combine state-of-the-art structural analyses and physical tests to demonstrate 

containment effectiveness. Full-scale testing is a very effective tool for both guiding and 

validating analytical engineering models of package performance and for demonstrating the 

compliance of package designs with performance requirements. However, deliberate full-scale 

testing of packages to destruction through the application of forces that substantially exceed 

credible accident conditions would be marginally informative and is not justified given the 

considerable costs for package acquisitions that such testing would require.

RECOMMENDATION: Full-scale package testing should continue to be used as part of 

integrated analytical, computer simulation, scale model, and testing programs to validate the 

performance of package performance. Deliberate full-scale testing of packages to destruction 

should not be carried out as part of this integrated analysis or for compliance demonstrations.”

Why did NRC not address full-scale testing as proposed by the NAS in the Draft Report? How 

might the findings of NUREG/CR-7209 be used to support full-scale cask testing as proposed 

by the 2006 NAS report?

Response: NUREG/CR-7209 is a compendium (compilation summary) of previously published 

analyses; it does not address full-scale package testing.

RH-4 In 1999, NRC began the process of developing a cask testing demonstration study as 

part of the Package Performance Study (PPS). The most recent NRC testing proposal (SECY05-001), approved by the Commission in June 2005, called for a demonstration test in which a 

cask mounted on a railcar is impacted by a speeding locomotive, and then subjected to a 30-

minute fully engulfing fire. “The staff’s proposed test plan as provided in this SECY is not the 

final word on this issue, as the project is subject to additional modifications and Commission 

direction once additional information becomes available.”

Why did NRC not address full-scale testing as proposed in SRM SECY-05-0051 in the Draft 

Report? How might the findings of the NUREG/CR-7209 be used to support full-scale cask 

testing as proposed in SECY-05-0051? 
10-51

Response: NUREG/CR-7209 is a compendium (compilation summary) of previously published 

analyses; it does not address full-scale package testing.

RH-5 Cask Designs Chosen for Analysis

Draft NUREG/CR-7209 does not adequately explain why certain shipping cask designs were 

selected for analysis, and why other cask designs were not selected. 

Information provided by NRC to Nevada’s U.S. Senators Harry Reid and Dean Heller in 

December 2015 indicates that the following packages have been approved, under 10 CFR Part 

71, or are under review, by the NRC for transport of spent nuclear fuel or high-level waste:

• NAC-LWT (Docket No. 71-9225)

• GA-4 (Docket No. 71-9226)

• 2000 (Docket No. 71-9228)

• NAC-STC (Docket No. 71-9235)

• TN-FSV (Docket No. 71-9253)

• NUHOMS® MP187 Multi-Purpose Cask (Docket No. 71-9255)

• HI-STAR 100 System (Docket No. 71-9261)

• UMS Universal Transport Cask Package (Docket No. 71-9270)

• FuelSolutionsTM TS125 Transportation Package (Docket No. 71-9276)

• TN-68 Transport Package (Docket No. 71-9293)

• NUHOMS®-MP197, NUHOMS®-MP197HB (Docket No. 71-9302)

• TN-40 (Docket No. 71-9313)

• HI-STAR 180 (Docket No. 71-9325)

• HI-STAR 60 (Docket No. 71-9336)

• BEA Research Reactor (BRR) Package (Docket No. 71-9341)

• TN-LC (Docket No. 71-9358)

• HI-STAR 180D (Docket No. 71-9367)

• M-140 (Docket No. 71-9793) (Naval Reactors)

• M-290 (Docket No. 71-9796) (Naval Reactors)

Two of the 19 package designs listed above are classified as confidential – restricted data 

because they are for naval reactors use. For the 17 designs that are not confidential, please 

provide the reasons why each one was, or was not, selected for analysis in NUREG/CR-7209.

Response: Discussion on the choice of packages can be found in NUREG/CR-7209 Sections 

4.4.1, 4.4.2, 4.4.3, 4.4.4, 5.1, 5.3.3, and 5.4.3; as well as Section 4 of NUREG/CR-6886; 

Section 4 of NUREG/CR-6894; Section 5 of NUREG/CR-7206; and Section 5 of 

NUREG/CR-7207. To summarize, the Baltimore (rail) Tunnel fire scenario analyzed packages 

(TransNuclear TN-68, HOLTEC HI-STAR 100, and NAC LWT) that can be shipped by rail. The 

Caldecott Tunnel fire scenario analyzed a light weight truck package (NAC LWT) that can be 

transported on the roadway. Likewise, the MacArthur Maze fire scenario and Newhall Pass fire 

scenario analyzed a light weight truck package (General Atomics GA-4) that can be transported 

on the roadway. 

RH-6 The final version of NUREG/CR-7209 should explain in detail why the GA-4 truck cask 

was selected for detailed analysis in all three highway fire accident scenarios. The GA-4 cask, 

to our knowledge, has never been used for spent fuel transportation in the United States. As we 

understand it, the GA-4 cask has never even been fabricated full-scale.
10-52

Response: The GA-4 truck cask was not selected for all three highway fire accident scenarios. 

As mentioned in Section 5.2.3 of NUREG/CR-7209, the NAC LWT was used to represent the 

package response to the Caldecott Tunnel accident conditions. The GA-4 package was used to 

represent the package response to the MacArthur Maze fire scenario and the Newhall Pass fire 

scenario. Section 5.3.3 and Section 5.4.3 of NUREG/CR-7209 discuss the selection of the 

GA-4 package. As noted in Section 5.3.3, the GA-4 package can transport up to four intact 

PWR fuel assemblies, “and therefore the potential consequences of package failure could be 

more severe than packages with smaller payload capabilities.”

RH-7 The final version of NUREG/CR-7209 should explain in detail why the NAC-LWT truck 

cask was not selected for detailed analysis in the MacArthur Maze fire accident scenario. The 

NAC-LWT cask, to our knowledge, is the primary truck cask currently available for spent fuel 

transportation in the United States. Failure to evaluate the performance of the truck cask used 

for the majority of U.S. spent fuel shipments over the past four decades, in the most severe 

highway fire accident scenario identified in the report, undermines the purported finding “that 

current NRC regulations and packaging standards provide a high degree of protection to the 

public health and safety against releases of radioactive material during real-life transportation 

accidents.” (Page 8-2)

Response: Section 5.3.3 of NUREG/CR-7209 discusses the selection of the GA-4 package and 

mentions the GA-4 package can transport up to four intact PWR fuel assemblies, “and therefore 

the potential consequences of package failure could be more severe than packages with 

smaller payload capabilities.” As noted in Section 4.4.3 of NUREG/CR-7209, the NAC LWT can 

transport one pressurized-water reactor spent fuel assembly.

RH-8 Fire Accident Scenarios Chosen for Analysis

NUREG/CR-7209 does not consider the Lac-Mégantic, Quebec rail accident and resulting fire 

that took place on July 6, 2013. Lac-Mégantic, is located in the Eastern Townships of the 

Canadian province of Quebec. An unattended 74-car freight train carrying Bakken Formation 

(North Dakota) crude oil rolled down a 1.2% grade hill from Nantes and derailed in downtown 

Lac-Megantic, resulting in the fire and explosion of multiple tank cars. Forty-two people died 

and half the town was destroyed. After 20 hours, the center of the fire was still inaccessible to 

firefighters. It is not obvious why this rail accident was not included in NUREG/CR-7209, since 

the Draft Report also includes references from the year 2015, two years after the Lac-Megantic 

fire. PNNL had the time to investigate and evaluate this rail accident. As a result of this 

accident, shipments from North Dakota have been rerouted along rail lines in the USA. Many of 

these rail lines are the same routes identified by the U.S. Department of Energy in its 2008 

FSEIS as potential shipping routes from nuclear reactors to Yucca Mountain. Similar 

derailments of oil tanker shipments involving nuclear fuel shipments could occur in the U.S.

NUREG/CR-7209 also does not consider the 1984 Summit Tunnel rail accident in Great Britain. 

This accident involved a tunnel fire with temperatures that reached 1530o

C, far hotter than 

temperatures in the fire accident scenarios evaluated by PNNL. While the Summit Tunnel is 

unique, that accident shows that hydrocarbon fires can be much hotter than those considered in 

NUREG/CR-7209.

Response: NUREG/CR-7209 is a compendium (compilation summary) of analyses that NRC 

previously published. These analyses included those describing a Baltimore Tunnel fire 

scenario (NUREG/CR-6886), Caldecott Tunnel fire scenario (NUREG/CR-6894), MacArthur 
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Maze fire scenario (NUREG/CR-7206), and Newhall Pass fire scenario (NUREG/CR-7207). 

The compendium does not analyze all past (or recent) accidents that have occurred.

Section 3.2 of NUREG/CR-7209 describes factors which can result in severe fires. In addition, 

the description of the modeling assumptions for the four accident scenarios analyzed and the 

severe nature of those conditions, including peak temperatures and fire duration, are further 

presented in Sections 5, 6, and 7 of NUREG/CR-7209.

RH-9 As shown by DOT data, while the probability of rail accidents has been declining, the 

accident rate for rail fires has been increasing. This is due to the fact that more oil has been 

moving by rail, primarily from the Bakken formation oil field in North Dakota to coastal refineries 

in the U.S. East, South, and West. While the total train accident rate declined between the 

years 2004 and 2013, the fire accident rate (which includes all fires, not just petroleum fires) is 

actually increasing. For the U.S. as a whole, the fire accident rate in the year 2013, was over 

twice as great as calculated by Sprung in NUREG/CR-6672. 

Response: NUREG/CR-7209 is a compendium (compilation summary) of analyses that NRC 

previously published. It is noted that the survey of railway accidents described in Section 3.1 of 

NUREG/CR-7209 refers to an analysis published in NUREG/CR-7034 (2011) that reflects the 

railway accident statistics for the period described in that publication; it does not indicate current 

accident rates.

In regards to the transportation of crude oil, the U.S. Department of Transportation (DOT) has 

the statutory authority under the Hazardous Materials Transportation Act to regulate the 

transportation of hazardous materials by all modes, including rail, roadway, air, and water vessel. 

Recent DOT actions that address the transport of crude oil can be found at:

http://www.phmsa.dot.gov/hazmat/safe-transportation-of-energy-products

These actions include implementing the May 1, 2015 Final Rule: “Enhanced Tank Car 

Standards and Operational Controls for High-Hazard Flammable Trains,” which include 

enhanced braking, enhanced standards for tank cars used in high-hazard flammable unit trains, 

and reduced operating speeds. 

Comments on transporting hazardous materials and rail transport regulations can be sent to:

Office of Hazardous Materials Safety

Pipeline and Hazardous Materials Safety Administration

U.S. Department of Transportation

1200 New Jersey Avenue, SE.

Washington, D.C. 20590-0001

RH-10 NUREG/CR-7209 also argues that long duration fires in a tunnel are unlikely because of 

poor ventilation and in the open environment, long duration fires are not possible because many 

railroad tracks are elevated above grade and are constructed on porous substrate. That is, 

according to NUREG/CR-7209, pooling of spilled flammable liquid is less likely in an open 

environment when compared with a tunnel environment, where the rail bed surface is often 

rock, concrete, or pavement. Historically many of the fires resulting from rail accidents have 

involved the leakage of flammable gas (such as propane), rather than a liquid.
10-54

These arguments in NUREG/CR-7209 are contrary to the facts regarding oil train fires. With 

train loads of oil tanker cars, in an open environment, fire often follows a derailment. As at LacMegantic, rail cars may be jumbled, one on top of the other. A fire over-pressurized nearby cars 

and a major conflagration ensued. With trains hauling 100 oil tankers, we are no longer talking 

about “pooling” of oil from one car. That is an outdated concept. Further, with a major fire, 

firefighters and emergency personnel cannot get close to the fire, for fear of additional cars 

exploding. Firefighters could not approach the fires in Lac-Megantic.

Response: NUREG/CR-7209 does not analyzes all past fire accidents or recent fire accidents 

that have occurred. However, NUREG/CR-7209 discusses many of the issues described 

above. Section 3.2.1 and 5.1.3 mentions that ventilation within a tunnel will affect fire severity 

and duration and the document further describes details of modeling assumptions considered in

the case studies analyzed. For example, Section 5.1.3 of NUREG/CR-7209 mentions that the 

Baltimore tunnel simulations assumed the tunnel was “ventilated in a manner that allowed the 

fire to be fully oxygenated, and the fire was assumed to burn until the entire inventory of fuel in 

the tank car was consumed by combustion.” In addition, Section 3.2.1 mentions the nature of a 

flammable liquid pool and a fully engulfing fire with its hot flame regions; the physics of this 

combustion phenomenon is relevant whether the fuel source is one or more oil tanker cars. 

Likewise, Section 3.2.1 of NUREG/CR-7209 discusses the potential inability of first responders 

to gain access to certain fires, which was one reason the Baltimore tunnel fire scenario was 

considered for analysis.

RH-11 Findings and Conclusion

The findings reported in the four fire accident scenario case studies do not clearly support the 

conclusion stated in the Abstract.

“The combined summary of this work on fire accidents demonstrates that current U.S. Nuclear 

Regulatory Commission regulations and packaging standards provide a high degree of 

protection to the public health and safety against releases of radioactive material in real-world 

transportation accidents, were such events to involve SNF containers.” (p.iii)

In fact, NUREG/CR-7209 reports computer modeling of cask performance in four selected 

severe accident fires that could potentially threaten public health and safety. In each case, the 

predicted fire conditions caused at least one of the simulated casks to fail (Pages 7-1, 7-2, 7-5, 

7-7, and 7-10). This is a significant finding that the Draft Report should have addressed in much 

greater detail. Moreover, historical accidents involving severe impacts, puncture, and/or 

immersion, combined in different sequences with severe fires, might further challenge cask 

integrity. These findings suggest that the NRC may need to reexamine cask safety standards.

Response: The potential consequences for the four accident scenarios are discussed in 

Section 7 of NUREG/CR-7209, which is a compilation summary of four previously published 

NUREG/CRs. Results of the four accident scenario analyses of spent fuel transportation 

packages that have been certified to 10 CFR Part 71, “Packaging and Transportation of 

Radioactive Material,” regulations indicate that the potential for release meets the regulatory 

requirements.

Comment 43: Robert Greene

RG-1 I approve the NRCs efforts to analyze Severe Fire Accident Scenarios. My opinion is 

that NRC regulations in this area have been more than prudent. If this analysis and public 
10-55

discussion leads to additional regulations, I have full confidence in the NRC to continue to 

protect the public in its customary professional manner.

But the requirement remains. We need to transport Spent Fuel Packages, particularly to 

designated storage sites. All your efforts need to make this capability a reality.

Response: The NRC staff notes the comment.







NUREG/CR-7209

FINAL

A Compendium of Spent Fuel Transportation Package Response 

Analyses to Severe Fire Accident Scenarios