BWR Description
Jacopo Buongiorno
Associa t e Pr of essor of Nuc l ear Science and Engineering
22.06 : Engineering of Nuclear Systems
Boiling Water Reactor (BWR)
Public domain image by US NRC.
The B WR is a D irect C ycle Plant
S ys t em pressure, MP a
7 . 136
3 4
Therm al ef ficiency , %
1 130
Electric power , M W e
3323
Core therm a l power , MW th
V essel I D / Thickness / Hei g ht , m
6.4 / 0.16 / 22
Core
Steam line Reactor vessel
Separators & dryers
Feedwater
Heater
T urbine generator
220
Feedwater tem p erature, ºC
1820
Feedwater flow rate, kg/s
13.1
Core exit quality , %
287.2
Core outlet tem p erature, ºC
278.3
Core inlet tem p erature, ºC
13702
Core m a ss flow rate, kg/s
764
Num b er of fuel assem b lies
5.2
Core shroud diam et er , m
Condensate
14 %
Core flow bypass
50.5
Core power density , kW /L
287.2
Steam tem p eratur e, ºC
Feed pumps
pumps
1820
St eam fl ow ra t e, k g / s
Recirculatio n pumps
Demineralizer
Image by MIT OpenCourseWare.
A .V. Ne r o, J r ., A Gui d ebook to Nuclea r R eacto r s , 1 979
Phase D iagram of Water
Pressure
Saturation line
7 . 3
Liquid
BWR core
V apor
278 288 T emperature [ C]
BWR Core
BWR C ore Layout
0°
Fuel B undle Contr ol Ce ll Bundle Peri phe ral Bun dle Contr ol B lade
270° 90°
180 °
T y pical Control Cell Core Layout
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BWR Fuel Assembly
Upper Tie Plate
Channel Fastener Assembly
Fuel Cladding
Fuel Claddding
Expansion
Spring
Fuel Channel
Lower Tie Plate
Plenum Spring
Fuel Pellet
Nose Piece Fuel Rod
Image by MIT OpenCourseWare. © source unknown All rights reserved. This content is excluded from our
F l bli h d t ll t
P07.cvs
Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.
Single bundle 3D view
F ue l assem bli es h ave a d uc t wa ll t o prevent vapor radial drifting
BWR Fuel Assemblies
Image by MIT OpenCourseWare.
Fuel Assembly Parameters for 9x9 Fuel Assembly
|
P a ra met er |
Valu e |
||
|
Fuel P e ll et OD (mm) |
9.55 |
||
|
F u el Pin OD ( m m) |
11.18 |
||
|
C l ad Thi c kness (mm) |
0.71 |
||
|
F uel Pin Pitc h ( m m) |
14.27 |
||
|
Ac tive F u e l r od he i g ht ( mm) |
3707.9 |
||
|
Tota l F ue l Rod hei g ht ( m m) |
4178.7 |
||
|
Part L e n g th Rod He ig ht ( mm) |
2436 |
||
|
Fu el P i n s / W a t e r R o ds p er Fu el Assembl y |
74/2 |
||
|
Numbe r of Par t L e n g th R o ds |
8 |
||
|
I nn e r/Oute r di amete r o f the water r ods (mm) |
23.37 /24.89 |
||
|
Duct Thi c kness (mm) |
2.54 |
||
|
C lea ranc e be tween duct and periphe r a l fue l r ods (mm) |
3.53 |
||
|
C l earanc e bet w een w a t er rods and fuel rods ( mm ) |
1.79 |
||
|
Assembl y Oute r Dime nsi o n (mm) |
137.54 |
||
|
I n ter - A s s e mbly Ga p (mm) |
14.8 6 |
||
|
Average L inea r Power (k W /m) |
16.46 |
||
|
Pre s sur e D r o p (kPa ) |
160 |
||
|
Average e nri c hment ( wt %) |
4.31 |
||
|
Average Discha rg e B ur n up ( G W d/t) |
56 |
||
|
R e fue l ing s c heme |
4 ba tc hes |
||
|
Numbe r of r ods with g a d olinia |
8 |
||
|
Ga dolinia conc entra t ion ( w t%) |
5 |
||
|
H y d r o g en to He av y M eta l R a t i o |
4 . 5 3 |
||
|
Void Coe f f i cient (p c m /% void) |
- 144 |
||
|
Fuel Tempe r at ur e Coef fi cient (pcm /K) |
-1.7 |
||
|
Approx ima t e Asse mbl y W e ig ht ( k g ) |
281 |
||
Control Blade
Image removed due to copyright restrictions.
Image by MIT OpenCourseWare.
BWR C ontrol Rod D rive System
Image by MIT OpenCourseWare.
BWR SPATIAL CORE PROPERTIES
(WITH CONTROL RODS PARTIALLY INSERTED)
Relative power
A verage void fraction
Critical heat flux ratio in hot channel x0.1
1.5
Relative parameters
1.0
0.5
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Bottom of core
Relative axial length
T op of core
Image by MIT OpenCourseWare.
1.8
1.6
1.4
1.2
0
17 25 33
42
50
58
67
Perc ent Ful l Inse rtion
0
67
1.0
.8
.6
.4
No da l po wer no rma lize d to 1. 0 ov er the core .
.2
(Bottom)
Axial Length of Fuel
(T op)
Relative Power
POWER IN FRESH FUEL ASSEMB L Y AS ADJACENT CO NTR O L R O D I S WITHDR A WN T O W A RD B O TT O M
Image by MIT OpenCourseWare.
“ BW R/6 : Gen eral D escrip tio n o f a BW R, ” GE, 1980.
Connection of BWR Core Desi g n to Neutronics
Why are the fuel rods spaced out more in a BWR than in a PWR? Why is the core power density lower in a BWR core than in a PWR?
What is the purpose of spatial fuel enrichment zoning throughout a BWR fuel assembly?
What function do the water rods perform?
W hy are t h e BWR contro l ro d s i nserte d f rom t h e b ottom o f t h e core?
Can dissolved boron be used as a means to control reactivity in a BWR core?
BWR Bundle D esign Advances
Extended burnup features
More fuel p ins ( 10 10 ) for a lower
heat flux
Heavier fuel loadings
Improved mechanical performance
“Barrier” cladding
Low growth, wear resistant materials
I m p r o v e d o p e r a t i o n a l p e r f o r m a n c e
Natural uranium blankets
Flow mixing grids to enhance margin to critical power
Part-Length Fuel Rods (Stability, SDM)
Large Central Water Channels ( Stabilit y , SDM )
Sophisticated poison & enrichment zoning
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our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse .
Control Rod
Fuel Rod
Part Length Fuel Rod
Image by MIT OpenCourseWare .
BWR Vessel and Vessel Internals
BWR Vessel
Lar ge vessel made of ring for gings to avoid welds in the core region
V e ssel bottom head accommodates CR penetrations
ABWR RPV beltline forging, w e ight: 127 tons; dimensions:
From : L.E. Fennern, ABW R Sem i nar – R eactor, 7.48 m outside diamete r , 7.12 m in side diamete r , 3.96 m high;
C o re & Neut roni cs. Apri l 13, 2007. material: ASME SA 508, Class 3 EQ.
© source unknown. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fair use .
BWR Vessel Internals
From : V. Shah, P. M acDonal d , Agi ng and Li fe Ext e nsi on of M a jor LW R C o m ponent s, 1993.
Steam Separators
Stea m Do m e
Dr y er Heig h t
Steam Dryers
Drain P ip e s Stea m + Dropl
ets
From : V. Shah, P. M acDonal d , Agi ng and Li fe Ext e nsi on of M a jor LW R C o m ponent s, 1993.
BWR Recirculation System
BWR R ecirculation System
BWR/6 ABWR ESBWR
Steam Dryers Steam Separators
Drivin g Fl o w
Steam Flow to T urbine
Feed Flow from Condenser
Core
Jet Pump
Recirculation Pump
External recirculati on
T en internal Relies on natural
pumps + jet pumps recirculation pumps circulation
Courtesy of GE Hitachi Nuclear Systems. Used with permission.
Traditional BWR vs ABWR and ESBWR
Parameter
BWR/4-Mk I
(Browns Ferry 3)
BWR/6-Mk III
(Grand Gulf)
ABWR
ESBWR
|
Power (MWt/M W e) |
3293/1098 |
3900/1360 |
3926/1350 |
4500/1550 |
|
V essel height/dia. (m) |
21.9 /6.4 |
21.8 /6.4 |
21.1 /7.1 |
27.7 /7.1 |
|
Fuel bundles (number) |
764 |
800 |
872 |
1 132 |
|
Active fuel height (m) |
3.7 |
3.7 |
3.7 |
3.0 |
|
Power density (kW/L) |
50 |
54.2 |
51 |
54 |
|
Recirculation pumps |
2(lar ge) |
2(lar ge) |
10 |
Zero |
|
Number of CRDs/type |
185/LP |
193/LP |
205/FM |
269/FM |
|
Safety system pumps |
9 |
9 |
18 |
Zero |
|
Safety diesel generator |
2 |
3 |
3 |
Zero |
|
Core damage freq./yr |
1E-5 |
1E-6 |
1E-7 |
1E-7 |
|
Safety Bldg V ol (m 3 /M W e) |
1 15 |
150 |
160 |
<100 |
Image by MIT OpenCourseWare.
BWR/6 R ecirculation Flow
Steam Dryers
1 unit
Steam Flow
to Turbine 1 unit
Steam Separators
Driving Flow
5 units
Feed Flow
from Turbine 1 unit
Core
4 units
Jet Pump
Recirculation Pump
6 units
2 units
Jet Pump M-Ratio
= Suction F low / Drive F low = 2
Courtesy of GE Hitachi Nuclear Systems. Used with permission.
BWR R ecirculation Pumps
Image removed due to copyright restrictions.
© Elsevier. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.
BWR Jet Pumps
H o l d d o wn As s e m b l y
In l e t
Je t P u m p N o z z l e As s e m b l y
R e st r a i n e rs a n d S up po r t s
C o re S h ro u d Mi x e r
R e st r a i n e rs a n d Su pp or t s
In l e t R i s e r
R e ac t o r V es s el W al l C o r e S u pp or t
D i ffu s e r a n d T a i l P i p e R e ci r cu l at i o n I n l e t
No z z l e – 1 p e r J e t Pum p R i s e r
© Elsevier. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/fairuse.
BWR Balance Of Plant (BOP)
BWR Power C y cle
Reactor Vessel
Steam
Separators and Dryers
Feedwater Extraction Steam
Turbine
Moisture Separator and Reheater
HP LP LP
Condenser
Generator
Core
Recirc Pum p
Recirc Pum p
Feed Pumps
Extraction Steam
Demineralizers
Heaters
Drain Pumps
H eate r s
Condensate Pumps
Courtesy of GE Hitachi Nuclear Systems. Used with permission.
“B W R /6 , Ge n e r a l D esc ri pt i o n o f a B W R , ” G E , 1 980
Radioactive Steam
Entire Power Conversion System becomes Radioactive
Shi e ldi ng i s N ee d e d
Reaction products from water:
O 16 + n N 16 + H 1 , T 1/2 = 7.2 s; , O 17 + n N 17 + H 1 , T 1/2 = 4.2 s; , O 18 + n O 19 F 19 , T 1/2 = 29 s; ,
Activation of corrosion p roducts:
Fe 54 + n Fe 55 , T 1/2 = 2.7 y;
Fe 58 + n Fe 59 , T 1/2 = 44.6 d; ,
Co 59 + n Co 60 , T 1/2 = 5.3 y; ,
Ni 58 + n Ni 59 , T 1/2 = 8x10 4 y; ,
Ni 62 + n Ni 63 , T 1/2 = 100 y; ,
Air E j ector
Removes An y Gases in Coolant Downstream of Condenser They Must be Held Up and Stabilized
Nobel Gas Fission Products Escaped from Faulty Fuel Pins (Xe, Kr isotopes)
Xe 135 Cs 135 + b - + g, T 1/2 = 9.2 h
Kr 88 Rb 88 + b - + g, T 1/2 = 2.8 h Kr 85 Rb 85 + b -1 + g, T 1/2 = 10.7 y
H 2 from Radiolysis of H 2 O
N Isotopes Produced by (O + n) Reactions Gases Leaking into C ondenser
BWR safety systems and containment to be discussed later in the course
MIT OpenCourseWare http://ocw.mit.edu
22.06 Engineering of Nuclear Systems
Fall 2010
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