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The Safe Production of H d b N l PHydrogen by Nuclear Power

Karl Verfondern

Research Center Jülich, Germany

3rd N l H d W k h "N l H d f G H i "3rd Nuclear Hydrogen Workshop "Nuclear Hydrogen for Green Horizon"May 20, 2009, Jeju, Republic of Korea

Energy-Related CO2 Emission per Capita

2

Forms of energy utilisation Other

Forms of Energy UtilizationFinal Energy Consumption

(10 224 MTOE in 2004)Coal7%

renewables4%

Combustible

• Final Energy Marketdominated by fossil fuels

• Electricity is 16 % of final

(10,224 MTOE in 2004)

Oil

renewables14%

Electricity is 16 % of finalenergy (25 % for OECD)

• Nuclear only for electricity43%• Penetration of nuclear into

two directions or combined

• Nuclear process heat has aElectricity

16%

• Nuclear process heat has ahuge potential in the energy sector !!!

Gas16%

• Combined Heat & Power saves resources & reducesGHG emissions Nuclear Energy

3Heat Market

gytoday

Driving Forces for Nuclear Hydrogen

• Nuclear energy can be takento produce hydrogen at alarge scale to replaceGHG emitting fossil fuels;

• Thus fossil reserves will besaved for later use insaved for later use inenvironmentally friendlyapplications;

E it f• Energy security fromextended fuel reserves andindependence of foreign oiluncertaintiesuncertainties.

EC High Level Group 2003

4

Advanced R t Future

Nuclear Power Plant Generations

CommercialPower

Reactors:

e.g., EPR, SWR-1000 Fusion

FutureReactorConcepts:e g HTR

ReactorsPWR, BWR, CANDU,WWER, RBMK, ...

1000,CANDU 6, ABWR, ...

FusionGeneration IV

Generation III, Generation III+Generation II

e.g., HTR

Gen II

Early Prototype-Reactors

Generation II

Generation IConcepts

FusionEPR / SWR 1000 HTR

1950 201019901970 2030 2050

5

Requirements for a Gen-IV Nuclear Reactor

• Safety improvements by innovative technologies• Competitive cost• New approaches for waste minimization & disposal• Reduction of proliferation risk• Improvement of public acceptancep p p• Extension of applications (electricity, heat, hydrogen)• Conservation and extension of expertise & competenceConservation and extension of expertise & competence

6

Very High Temperature Reactor (VHTR)

• 400-600 MW(th) for electricity and process heatproduction;

• Helium-cooled, graphite-moderated, g pthermal spectrum;

• Gas outlet temperatureGas outlet temperature of 900-1000 °C;

• IHX for heat transfer toIHX for heat transfer to H2 production plantor gas turbine.

7

AVR

Experience with HTGR

HTTR

8HTR-10

HTTR

Intermediate Heat Exchanger (IHX)

HTTR

SteinmüllerHeatrix

9Balcke-Dürr

Short-Term Option: Steam Methane Reforming

appears to be a reasonable first step

Steamreformer

Steamgenerator

• most widely appliedconventional productionmethodreformer g

• savings of ~ 35% of NG,if process heat is fromnuclear

He circulator

Electricheater

nuclear

• tested under nuclearconditions in pilot plantsi b th G dHe circulator

Oarai, Japanin both Germany andJapan

10Jülich, Germany

Combined HTTR/SMR Complex

Reactor System Hydrogen Production System

Control centercenter

Containment vessel

Hot gas duct

Steam reformingIHXReactorvessel

CH4 + H2O → 3H2 + CO

11

4 2 2

Potential Ha ards in aPotential Hazards in a Combined Nuclear/Chemical Complex

• Thermal turbulences induced by problems iny psteam reforming system;

• Tritium transportation from core to product gases;Tritium transportation from core to product gases;

• Fire and explosion of flammable mixtures withprocess gasesprocess gases.

12

Tritium and Hydrogen Flow Paths in the HTTR

Sources:- fission (51%)- lithium (34%)- helium (15%)

13

( )

Problem Tritium

• High mobility of both HT and H2 at high temperatures- radiation problem to consumer

i bl i hiti t t- corrosion problem in graphitic core structures

•Measures of reducing HT and H2 transport- oxide layers (doping with O2)- gas purification system

intermediate circuit (doping with H O)- intermediate circuit (doping with H2O)

•Results from German and Japanese studiesHT l l i d t d d ffi i tl l- HT level in product gas deemed sufficiently low

- permeability of oxide layer reduced by factor 100-1000

14

Tritium in German Legislation

• According to German Preventive Radiation Protection• According to German Preventive Radiation ProtectionOrdinance, specific radioactivity limit for any fabricatedproduct is 0.5 Bq/g.p q g

• Exception from the rule:No licensing required for fossil products to be refined byNo licensing required for fossil products to be refined bynuclear process heat with tritium content < 5 Bq/g.

15

Possible Causes of Fire/Explosion in HTTR/SR

16

Safety Design against Fire and Explosion

Reactor System Hydrogen Production System

Take safe Take safe distanceTake safe distance

Take safe distance to storage tank

- Prevent leakage and ignition

- Prevent inflow into nuclear building

- Detect leakage and

17

gshut off natural gas line

JAEA A l ti l St d fJAEA Analytical Study of Explosion/Fire Scenarios

Accident scenarios considered

Inaba 2004

• Pipe rupture with NG release175 m distance, 35 kg/s NGignition at 140 mresult: 6.3 kPa at reactor building

• LNG pool fire• LNG pool fire6 m dia pool

• Detonation inside containment

18

Detonation inside containment16.2 kg methane leaks within 0.1 s

Flame Velocities of H2-CO-Air Mixtures

PNP Vapor Cloud Explosion Program

19

Breitung 2000

Fraunhofer Institute of Chemical Technology (ICT)

Hydrogen Storage Option as Liquid

• Option: stored as LH2 in underground tank;

• IAEA recommended assumptionpof cryogen vaporization rate(too low for LH2)

Ob i 30 66 / i O erpress res• Observation: 30-66 mm/min(can be up to 1000 mm/min)

• Assuming tank of

Overpressures

• Assuming tank of dia. 15 m, height 10 m,vaporization takes2 5 h2-5 hours

20Zabetakis 1960

German BMI Guideline (1974)for the Protection of NPP against External Explosionsfor the Protection of NPP against External Explosions

R = 8 * M 1/3

Protection by means of safety distance

R = 8 M 1/3

100% for unsaturated HC and non-liquefied gases50% f li fi d d50% for gases liquefied under pressure10% for gases liquefied at low temperatures0 3% for combustible liquids0.3% for combustible liquidsTNT equivalent for explosives

21Minimum Distance: R ≥ 100 m

German BMI Guideline (1974)

Protection by means of design against pressure wave

22

German BMI Guideline (1974)

• Guideline was the result of experts‘ opinion.

• It was confirmed by PNP gas cloud program that gas mixtures typical for PNP cannot generatepressures beyond the design curve.

•Guideline, however, must not be applied to nuclear process heat plants.

If applied to HTTR/SR:ppk = 3.7 R = 205 m for LNG storage tank(not considered: inventory in steam reformer)

23

US Regulatory Guide 1.91 (1975)

LNG: 400 m3 169 t 1859 t TNTR = 2.2 km

( h th t tt d t i k b ffi i tl l )24

(or show that attendant risk be sufficiently low)

H

Safe Design of Gen-IV Concepts

H2storage

Reactor building

Thermo-chemical

Example:Heat exchange Water splitting

process

France

25

Further Safety Research Needed

• Safety aspects in nuclear hydrogen production systemsbased on I-S process, HT electrolysis

• Sufficient cleanliness of nuclear hydrogen (tritium)y g ( )

• Effect of thermal turbulences on systems others thanHTTR/SR (design of components).( g p )

• Protection of chemical plant against nuclear accidents(confinement vs containment)(confinement vs. containment)

26

Thank youf ki d tt ti !for your kind attention !

대단히감사합니다!

27email: k.verfondern@fz-juelich.de