U.S. Hydrogen Safety Standards, Guidelines, and Practices
Robert ZaloshProfessor Emeritus
Worcester Polytechnic InstituteWorcester, MA
2HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
U.S. Organizations Generating Hydrogen Safety Codes, Standards, & Guidelines
Consensus Standards Writing
Organizations•ASME
•ASTM
•CGA
•CSA America
•ICC
•NFPA
•SAE
•UL
Authorities Having JurisdictionFederal Government AgenciesState and Local Agencies and BoardsInsurance CompaniesBuilding/Facility Owners
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HYDROGEN APPLICATIONS WITH FIRMLY ESTABLISHED FEDERAL
GOVERNMENT SAFETY STANDARDS
Aerospace:
Department of Energy Facilities:
Commercial Nuclear Power Plants:
U.S. Nuclear Regulatory Commission
4HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
HYDROGEN APPLICATIONS WITH EVOLVING SAFETY STANDARDS
Hydrogen Fueled Vehicles
Hydrogen Vehicle Refueling Facilities
Stationary Hydrogen Fuel Cell Systems
Onsite Hydrogen Storage
Hydrogen Generated or Used in Manufacturing
Facilities
5HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
NRC Requirements for Hydrogen Generated in Accidents Involving
Degraded Reactor Cores
Existing Plants as of 2003
• Maintain hydrogen concentrations below the level that could cause loss of containment if ignited
• Install and maintain reliable H2 detectors
New Plants After 2003
Either
• Inert Containment Building or
• Maintain H2 concentrations < 10 vol % for complete fuel cladding
reaction with water
• Account for local H2 detonations
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Size and Strength of Existing Reactor Containment Buildings: 1200 MW Plant
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Special Strategies for Different Types of Reactor Containment Buildings
BWR Mark 1 and Mark 2 Containments are
Inerted
BWR Mark 3 and PWT Ice Condenser
Containments Use Deliberate Ignition Devices
PWR Large Dry Containments Use Mixing to
Prevent Detonable H2 Concentrations in Large
Parts of Containment, and Use H2 – O2
Recombiners to gradually remove hydrogen
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Deliberate H2 Ignition Via Diesel Engine Glow Plugs Distributed Around
Containment Building
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Glow Plug and Heated Coil Surface Temperatures Required to Ignite
Hydrogen – Steam Mixtures
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Passive Autocatalytic H2-O2 Recombiner
Used Extensively in French
and German Nuclear Plants
Starting to be used in a few
U.S. PWR Large Dry
Containment Buildings
11HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
Hydrogen Fueled Vehicle Safety Standards
1. Fuel Tank Standards:CSA America HGV4SAE J 2579ISO 15869
2. Pressure Relief Device (PRD) Standard: CSA PRD1
3. Vehicle Fuel Cell Systems:SAE J 2579UL 2267 for fuel cell powered industrial lift trucks
4. National Highway Traffic Safety Administration is currently developing a H2 fuel system standard
12HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
Four Types of H2 Vehicle Fuel Tanks: Rated for 350 to 700 bar
Type 4: Composite with non-metallic liner
Type 1: Metal (intact after crash)
Type 3: Fully wrapped composite with thin metal liner
Type 2: Hoop-wrapped composite (fiber + resin) with thick metal liner
13HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
Some Fuel Tank Requirements in Standards
Ratio of Burst Pressure to Working Pressure : 2.25 to 2.45 for new tanks, depending on standard and type of tank.Ratio of Max Fill Pressure to Working Pressure: typically 1.25 (accounts for compression heating and pressurization during filling)Cycle Life: 5000 to 15000 cycles depending on standard; some standards require cycle counerto be installed.Fire Resistance Test: Must depressurize safely (via PRD) during fire exposure
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Tank Undergoing Hydrostatic Pressure Cycling Test
Failure Mode
must be leak
rather than burst
15HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
Fuel Tank Maximum Pressure During Fill = 1.25 x Tank Working Pressure
Pressure Settles due to cooling after fill
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Burner Length = 165 cm
Hydrogen Tank Bonfire Tests
Test in Tunnel to contain tank fragments if rupture
occurs
Outdoor Test
17HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
Hydrogen Jet Flame from PRD Actuation during Tank Fire Exposure
Hydrogen Tank on Left and Gasoline Tank on Right
18HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
Tank Failure with Hydrogen Fireball Formation if PRD does not actuate to
vent tank
10 msec 107 msec45 msec
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Hydrogen Fireball Rise
997 msec 1240 msec
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Type 4 Tank Fragment
14 kg fragment found 82 m east of original tank location
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Other Required Tank Tests
Gunfire Test
Drop Test
Type 3 Tank undergoing crush test
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Hydrogen Vehicle Fuel Dispensing Standards
23HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
NFPA 52 Requirements for H2 Fueling Stations
Documented Hazard Analysis
Hydrogen gas and flame detectors must provide
coverage of all storage, compression, and refueling
equipment.
Either outdoor location or indoor location with one side
predominantly open and roof designed to facilitate
hydrogen venting
Distances for Division 1 and Division 2 hazardous
locations requiring listed electrical equipment
Setback distances to various buildings and roadways
24HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
NFPA 52-2006 Requires Fuel Dispensing Connectors to satisfy SAE J 2600 Standard
Lever actuated 3-way valve to allow venting of residual hydrogen via hoseline back
to dispenserSAE J 2601 Communicating Connector
25HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
Example of State Guidelines for Fueling Stations
September 2004
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Hydrogen Dispenser Safety Features Recommended in California Guidelines
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Hydrogen Dispenser with Safety Features
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Virtual Refueling Station Code Compliance Web Site
http://www.hydrogensociety.net/VFS3/virtual-hydrogen-
fueling-station.php
Developed and maintained by Canadian Transportation Fuel Cell
Alliance
Allows users to build a virtual refueling station, and determine if it is in
compliance with specific codes and standards.
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Standards for Stationary Fuel Cell Systems
New NFPA Hydrogen Technologies Committee will Develop New NFPA 2 Standard
30HYSAFE SUMMER SCHOOL LECTURE Bob Zalosh, August 24, 2006
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CONCLUDING REMARKSNot to worry if you find the tangled web of U.S. safety codes and standards confusing and frustrating; it will be changing soon anyway.Even if new standards aren’t significantly simpler and more consistent, Web-based tools to access standards and guidelines will facilitate access and understanding.Need more progress in harmonizing U.S. hydrogen standards with European and international standards; requires cooperation from all standards development organizations.