View
222
Download
0
Category
Preview:
Citation preview
(-
Pebble Bed Modular Reactor
Design and Operation
Pebble Bed Modular Reactor Basics
• High Temperature
• Graphite Moderated
• Graphite Core and Graphite Core Support Structures
* Helium Coolant
• Brayton Cycle
• Gas Turbines in Power Conversion System
* Spherical Ceramic Fuel Elements
* Continuous On-line Refueling
* Passive Response to Design Basis Accidents
PBMR Plant Specifications
Maximum Rated Power
Continuous Stable Power Range
Ramp Rate
Step Change
Load Reject w/o Trip
General Overhauls
Emergency Planning Zone
Plant Operating Life
120 MWe
0-100%
10%/o/min
10% Power
100%
30days/6Yrs
<400 Meters
40 Yrs
High Pressu'eTurbine LowP ressureT urbi ne
Pov~erTurbineRecupea~tor
High P reswire LowP resare I Compressor Compressor
iLHeium irjeclion and Heium hnjeciion frum HlCS remwxo tomn HI CS
- - -
PBMR Helium Flow Process Diagram
Generator
Irter~o~oer PrL-cooler
I
2 BMR Thermal CycleP B M R
Sea water 121-C OUT
400C 10
U) 0)
U w
1.48 m3/sec" 180C Sea water
IN
- em r
C
P Q M
EZ�ZJ
L�J
-KzJ
11(S
Power System Helium Flow
Eý c
I~~ I
Reactor Vessel
HPT __ LFT
Core Conditioning System
PBMR MPS
GeneratDr
I
IF-
Pre-Cooler-
Recuperator----
PTG
Start-Up Blower System
PBMR Main Power System
)
*1*rA
AW II I
Reactor Pressure vessel conditioning Sytem
Reactivity Control System Drives Reserve Shutdown System
w (A 2. 0. - 4 0
4 4 n R
4
2 I
1 4
-46
-13
-'I U, (A 'C -U -' C a
I a. a
3 S 0
'I
(D
0
CO)
(D
CL
(D
900
-01 1800 E) -- 0• o -0 0 \ 0
Graphite0
GraphiteCoeRfetrBokLyu
(Side and Bottom)
PBMR "Pebble" Fuel Elements
PBMR Annular Core With Center Graphite Pebbles
Spent Fuel Tank
Fuel Handling and Storage System
5mm Graphite layeir
Coated; pa rticles Imbedded 7in' Graphite Matrix
Dia. 60mm fuel Sphere.
-- APyryt'cCtabofl4oi01 o~mm Slli~n d bldariirdod g ýsrvoo
I•~diz aCubffei§9511 000mm
Dia; 0,92mm
Coated Particle. Urani~um'Dioxid'e Fuel. Kernel
PBMR Fuel Element and (TRISO) Coated Fuel Particle
TRISO Coated Particle and Pebble Fuel Element Design
TRISO Coated Particle Design
Uranium Dioxide Kernel
Low Density Pyrocarbon Buffer Layer: Porous plenum volume for fission gas Accommodate irradiation-induced kernel swelling
Inner High Density Pyrocarbon Layer: Retains most of the fission products; Protects the next (SiC) layer from chemical attack from
Silicon Carbide Layer: Main barrier to the escape of gaseous and solid fission
Largest contributor to particle mechanical strength
Functions as a pressure vessel 110mAg readily diffuses through layer
fuel fission products
products
Outer High Density Pyrocarbon Layer: Protect SiC layer from chemical attack outside the particle Adds strength to the SiC layer.
Pebble Fuel Element:
TRISO particles in spherical graphite matrix fueled zone
KERNELMATRIX
F' IBUFFER LAYER
lb, I
FUEL-FREE
FUELED ZONESHELL
INNER
SiC-LAYER
PyC-LAYER
OUTER PyC LAYER
Pebble Fuel Element and TRISO Particle
Kernel
Buffer
PyC
Fission Product Concentration in Intact TRISO Particles
I I I. I 4*
,
1200. 140.0. 16..00 l80.0 2000.
IE+00
1E-O1
1 E-,2,
IE4-3
1E"64
1E-05
1E-0.6-"24.00.
Fuel Temperatures [°C]
TRISO Particle Failure Fraction Vs Temperature
0
0
22001000 2600
'I 3k - * 0 0.r
f
-r
U) 1 -3 --
.0 10-4.-_,j - -17000C_ ,-,40.-0o co ---/-/ -- "3VR82/20
I o,--°" I.-°-K Iv3/,2
._ 10-5 i• -,- o
°HFR'K3I1
•" o •o--.oFRJ2-K13/4 o
o0.A-I 1,.. 7 0..0" 0 A.R74/11
10-6 ... ~~2'V822
10-7
10-80 100 200 300 400 500
Heating time (h)
Cesium Release in Isothermal Heating Tests
(German TRISO Coated Pebble Fuel)
/
I
Reactor Cavity Cooling System Surrounding Reactor Pressure Vessel
MAIN CRANE
HICs Helium Inventoy Control System •
NEW FUEL CASKS
HMS Helium Make-Up System If"
Turbi[no FH5S Fuel Handling &- r u
Storage System Turbne Spent fuel contan VT
P oaverTurblne
FHSS Fresh Fuel Loading Machine
FHSS Recuperator
Fuel lHandling Storage System Gas Cmponents
PEBBLE BED MODULAR-REACTOR1 RCCS ____ ___ ____ ___ ____ ___Reactor Cavty
MAIN POWER SYSTEM Cooing System WITH
SUPPORT SYSTEMS
PBMR Main Power System with Support Systems
PBMR Module Elevation Relative to Grade Level
- .---
Layout for 10 PBMR Modules
Pebble Bed Modular Reactor
Safety Objectives and Characteristics
Safety Objectives and Characteristics
Retain Fission Products
o Manufacture PBMR fuel with very low TRISO particle defect rate
matching German quality standards
Qualify (Test) PBMR fuel for PBMR operating and accident
conditions with performance equivalent to German pebble fuel
Ensure that core operating and DBA conditions do not exceed fuel
qualification envelop (e.g., 80,000 MWd/t, 12500C max operating
temperature, 160000)
Support high temperature performance with ceramic fuel materials
Control graphite chemical attack (e.g., oxidation from air, moisture)
Safety Objectives and Characteristics
Ensure Core Shutdown
or Provide diverse active scram systems (i.e RCS, RSS) for
anticipated transients
e, Provide passive reactor shutdown mechanisms (i.e., low excess
reactivity with strong negative temperature feedback) for potential
core heat-up accidents
Safety Objectives and Characteristics
Ensre deqateCore Heat Removal%
Operate at low core power density and core with large
thermal heat capacity (i.e., for slow accident response times
and limited core temperature rise)
Utilize coolant which does not change phase (i.e. no abrupt
reduction in Helium heat transfer coefficient)
Provide for passive decay heat removal processes and
equipment for transients and accidents (i.e., no active core
cooling systems or components)
Decay heat removal does not rely on He coolant
Safety Objectives and Characteristics
LiitPoetialfr rahieChemclAtk
Use Helium coolant (i.e., He is chemically inert)
Operate He/water heat exchangers with He-side pressure
above water-side pressure (i.e., He leaks into water side)
Locate HXs below elevation of the bottom of the core and
minimize the water volume on the water side
Use RPB and PCSPB specifications for low failure potential
Use confinement building to limit available air volume for
graphite oxidation following a pipe break
Safety Objectives and Characteristics
Limit Need for Operator Actions_
Utilize passive safety functions that do not rely on near-term
operator actions
Minimize the adverse effects of operator errors
Pebble Bed Modular Reactor
Accident and Transient Analyses
PBMR Accidents and Transients
"* Loss of Forced Cooling Transients - Depressurized (LOCA) - Pressurized
"* Reactivity Transients - Failure to Scram - Over Cooling - Rod Withdrawal - Rod Ejection - Moisture Ingress - Pebble Bed Compaction
"* Chemical Attack - Air Ingress - Moisture Ingress
S (4)) LUj
Oat 001. 08 09 Oz 0 I II0
II I
II I
axainjedadwej AdU LunwOAV I
I -I. . . . .. . . . .
I . . . . . . . . . . . . . -00
I I
- --I- - - - - - -0 8 -I
I I
InI -e
" I 1 - I I L ------ ------
o3070 a uJnp uojlnqJJJSIa anjejadwa.lB :aool "ad &Ngd Mk 99
N UOA^ i 4UeIOOO o sso-l 9 "6!
Arom ýq VR -,.2 0 i,-la 6 "
8e--fri'e-,b, "' VVI- Bericli-le 1,2clo VDr Verlay (/13y)
Obere Schmelztemperatur 1280*C
so I
40
OAuBencore
llinnencoreý Anzahl Kugein
20 1
10
0900 1000 1100 1200 1300
Maximaltemperatur (*C)
Abb. 6: TemperaturmeBkugeln (oben) mit 20 Schmelzdrahten (Aussc
aus R6ntgenaufnahme, Mitte) zeigten teilweise unerwarte
hohe Temperaturen (unten).
Pebble Bed Modular Reactor
Pre-Application Review Objectives and Activities
PBMR Pre-Application Review Objectives
To develop guidance on the regulatory process, regulations framework and
the technology-basis expectations for licensing a PBMR, including identifying
significant technology, design, safety, licensing and policy issues that would
need to be addressed in licensing a PBMR.
* To develop a core infrastructure of analytical tools, contractor support, staff
training and NRC staff expertise needed for NRC to fully achieve the
capacity and the capability to review a modular HTGR license application.
PBMR Pre-Application Review Scope
Selected Design, Technology and Regulatory Review Areas:
Performance
• Nuclear Design
* Thermal-Fluid Design
Hi-Temp Materials Performance
° Severe Accident Source Term
Containment Design
° PBMR Regulatory Framework
• Human Performance and Digital I&C
0 Prototype Testing Program
0 Probabilistic Risk Assessment
0 Postulated Licensing-Basis Events
0 Fuel Cycle Safety
a Emergency Planning
0 SSC Safety Classifications
0 Fuel Design and
PBMR Safety Significant Review Issues
• Fuel Performance and Qualification
0 Passive Design and Safety Characteristics
0 Accident Source Term and Basis*
0 Postulated Licensing Basis Events*
0 Prototype Testing Scope and Regulatory Credit
• Containment Functional Design Basis*
• Emergency Planning Basis*
0 Risk-Informed Regulatory Framework*
• Probabilistic Risk Assessment
Commission Policy Decision is Likely Involved
Recommended