x -" Assess, •
SREACTOR PHYSICS':
Shtdown M rgins.-, •,):i :•
Reacti~t Feedback' •.- - :ii / ,••:••f : Inherent SaAfetysmeii-..
Powe Denity Distribuin
.,•! ~(Design and Control) . .: _:.,.•• .••• Modu.la. . .. ".a.to "y i
"... . . . . . .... . . . ...... . . . . .
* Shutown.Magins, . ." .
_ eatviyFed ac ,, .,•:-,
•: Modular HTR-2 NPP, Reactor Physics
TOV NORD GRUPPE
TUV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology
El
- 3
I (�) � -4t�.. I
Eli FW� . -� �
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0. Cu =0
-�7E > . -�E'
o o 4
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(3�
U)
Co .1-I
0 Co
Cu I
I-
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-�
I. k �*
ma a. a. = U
a U 0 =
2= I
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E
-2
0)
-c
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U)
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5)
- - - - - - - - - - - - --- - -
-------------------- 4---
4 .7 .. ... ..
0 #. 0 0, 0~
0cc CD . 4' .RU (
UIF X-C 4a- Rol
miI>
7-7 -7779ýý ý ý Y-.; A-Z, ZY:.7
IN
'V
Modular HTR-2 NPP, Reactor Physics
TUV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology UEJkOMLp
TUV NORD GRUPPE
�.Lbnh1LE��E� *'�
Scheme of Reco PhsisCafculatiorF' V. S.O. P ý(Very. Suvperior ld rogram4s7'7
Nameof the Application" .Result. Program Vf, th: ..
GAM/THERMOS Spectral Cros Section of, Z L/T.,,, Calculation Core-Caland eflecaf
tor Regions~
CITATION Diffus ion M cationn..---ul. CaIculation . Factor, Power •
Density Map
FEVER Burnup- Nuclide-Densities,:;: "Calculation
THERMIX Temperature- Temperatures of:
Calculation Fuel (U02)
- Core-Graphite
- ReflectorGraphite in all Regions
Modular HTR-2 NPP, Reactor Physics
TUV HannoverlSachsen-An halt e.V. Division Energy and Systems Technology TUV NORD GRUPPE Eskoffi94*
iI I
<0 M ill II -- --
Cow -4-70
(nU Cn DC
(D C
o)- -7 - - -
CDCID
0 b ,o: '
-' �,. �
i] • : ,
-- -- -- -- ---- ---------------
C16
•'•;• . :.•0.. ,.: .'
o~c ca C ~>
*. ?' ,-..,: . ..'A. : . -
:a.m
W W
o Of C ,<,,
<U'n C
V
i--arual rower kAeIII I, I [lip I I iLUIC)
Accidental Reactiviy Increase
Partial Power - Zero Power
Efficiency of 5 of 6 Rods
+0,5
+0,1
- 2,6
-0,4%
Modular HTR-2 NPP, Reactor Physics
TUV NORD GRUPPE
Calculationre of Shu(:Dowg•. Rins 1.i
Starting Core (BOOC) ReactivityBalane Ho hut- Down
Control Reserve 100 -90-100% +2
Reactivity Compensation forý, Partial Power (Xenon, ,Temperature)+ 0,6%
Accidental Reactivity Increase -+:•0,5 %
Partial Power- Zero Power -0,11.%
Efficiency of 5 of 6 Rods-." - -3:,3;4%
Steady State Core Reactivity Balance Hot Shot Down
Control Reserve 100-50-100 % + 1,2 %
Reactivity Compensation for n, A 0/J ,
TUV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology
Filter for and" Adiinal"Aspects o HTR.D.sgn(Sutd Safety)
"Event, Effect PWR .. R'ý
Rod ejection yes no0
Uncontrolled rod withdraw .yes yes,
Boron dilution ..- ,; ysno
Water ingress s (no)
Uncontrolled fuel addition "no. no yes "" C cr
Collapsing of holes in the core no . yes
Loss of Collant Accident .yesy yes>
Loss of Flow Event yes (no),
Rod drop with reactivity gain no. yes
Core densification (o yes,:
Boron-loss by earthquake yes no
Burn out of poison in structural materials no yes
Uncontrolled cooling of the core yes yes
Temperature increase of the reflector no es)
Error in excess reactivity (no) yes
ATWS yes yes
Changes of reflector geometry no yes
Burn out of reacitivity control devices yes yes
Modular HTR-2 NPP, Reactor Physics
TUV Hannover/Sachsen-Anfhalt e.V. Division Energy and Systems Technology TUV NORD GRUPPE
,7t5
•"Rules 7 neetSft
Rules HTR D sign Filter-, ac 'Addi
BMVI-Kriterium 3.2 * Negative Temnperatufr
RSK LL, 3.2 - Coefficient.,
DIN 25405 . * Negative Power -Cefficient
KTA 3101.2 . Accidental ReactivityI:ncrease limited sto that 'thereator ican
IAEA Safety Standards' beshut down and tp be sht.on emd~ pera w...
IAEA Safety Guides, ture.f the fuel elemen•ts•,,. remaining beloW.a'- specified Value:
Temperature Coefficient of the fuel: Negative
Temperature Coefficient of the fuel-graphite: Slightly
negative, a small positive value at Xenon-maximum
Temperature Coefficient of the reflector: Slightly positive
• Inherent Safety confirmed
Modular HTR-2 NPP, Reactor Physics
TUV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology TOV NORD GRUPPEE*-10-wp~f
e a
sibilitieso accen increase o reactivity • Core densification, by erhqu'ke
y ar qU
" Water ingress into the core
* Uncontrolled withdraw of reflector rods
P
Earthquake §
STime'
S•'•-: -'.. " ,.......
Water ingress_
""- Water density
',• p
Uncontrolled withdraw
or reflector rods
-' Time/depth
Modular HTR-2 NPP, Reactor Physics
TUV HannoverlSachsen-Anhalt e.V.Division Energy and Systems Technology TUV HORD GRUPPE
'I
4,
I
I4-
PRoi
No- Time
d drop
".-- Time
Modular HTR-2 NPP, Reactor Physics
TOV NORD GRUPPE
TUV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology
Inh. nt aft
Search for possibilities of accidental increase pf -, reactivity : . . . . . ". . , -.
Change of reflectorgeometrie.,
"* Uncontrolled cooling of the c'ore'
"" Rod drop .
Change of reflector geometry .
.. 'Time
Uncontrolled cooling..
- 22
r 27
14-
- - -- - -- - U -
-U CU Co
~---~ca
o 'a
*~ .j-- .JT .7 ... ..
ens.~ ~" ditiu' is*6b
During opration the power de nity dio
in a proper shapc-e by:'
Reactor Physics calculation,
Measuring the depth of the reflector rods and: by
adjusting the rods to the same depth,'
Measuring the height of the columns of th'' ma
sphere shutdown system. and by: adjusting the'm to.. the same height.
The power density distribution is controlled by the 3 x 4
neutron flux instrumentation outside the RPV.
An indirect control of the axial shape is given by
measuring the helium-inlet and -outlet temperatures.
Under safety aspects the power density distribution is
important as start condition for accident analysis.
Modular HTR-2 NPP, Reactor Physics
TUV HannoverlSachsen-Anhalt e.V. Division Energy and Systems Technology TUV HORD GRUPPE
II
I wCD CO)
0
m CD
C', (I)
CD
CD 0
(0
(DH C', 7;m
C,) G)
0
0)
(0
0
0*"*
- - ----- -- - - - - - - - - - '
(D,,
(D
CL
'Mi
0 14
-o
-I
= 0
.3
I
1'�
I.
U120
-200
,Scram-, (Power)Scram (C ooa nt.Temperati
<10
Decay Heat
Decay Heat
•ire )...........- ...:
S. .. :/D 5 0 ::o ........ .
5. .
-1050 .Ct-'
-1240. C
Conditions:
"* Conservative integral power, only area cooler system
"* Skipping of first reactor protection limit -- R',; cs-k-•4
Result:
Fuel temperature well below limit: 1620 °C, also for different starting conditions like zero power, partial power.
Modular HTR-2 NPP, Reactor Physics
TOV NORD GRUPPE
ddhtldent .. I..Acid enAn a lysi .
Reactivity Accident .... , 2:.
Uncontrolled withdraw of reflector rods
Time Power-' , Action Max: Fue [sec] [%. .. <Tempeiratu r&;
0 105 -- 80C
(12
90
120
3700
- some hours
TUV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology
"Acd ,ien.t Analysis
LUS5 UI V_,UUtdI L /PWAAUHI L
Starting conditions:-~n4-
- Reactor power: 105 % (limitation system limit)
- Inlet temperature 280 0C (near protection system limit)
_ Outlet temperature: 750 ,C 6i(near protection system limit)
2. Scram limit -.
Leak of 65 mm"C(
Calculation
Programs TAC 2D (TOV) and THERMIX
Detailed 2-dim model with evaluation: of the main tolerances
(1 a-value):
- Decay heat 2,8 /0 - Local power density ± 5 %
- Fuel heat conductivity+ 1,15 W/moK
- Effective core heat conductivity ± 5 %
Results for maximum fuel temperature (incl. 2 a-tolerance)
THERMIX TAC 2D limit
1608 0C 1625 0C 1620 0C
(- 1% of the core > 1500 °C)
Modular HTR-2 NPP, Reactor Physics
TUV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology Eskom_8.pp4
TUV NORD GRUPPE
A.
I .=-:• •';f"•
a
Accident Analysis
Loss of Coolant Accident
Additional temperature results (THERMIX)
Position
Reflector rods
Core container wall
Core container bottom
RPV wall
RPV bottom
Outlet temperature
Maximum temperature
880.
500
380
360
350
750
0c
0C
0C
0C
0C
0C
Design limits
650
500
500
500.
500 900
0C
6C 0C
00 00
I
Modular HTR-2 NPP, Reactor Physics
TOV Hannover/Sachsen-Anhalt e.V. Division Energy and Systems Technology EBkoM_8.Wp
TUV NORD GRUPPE
The high temperatures of the reflector rods do not affect the
conceptual design, because:
- The mechanical integrity of the rods can perhaps be approved by additional experiments,
- The shutdown safety is not affected by a loss of the rods during temperature increase,
- The rods can be changed.
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