ML20009F202
| ML20009F202 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 07/31/1981 |
| From: | ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY |
| To: | |
| Shared Package | |
| ML19277A067 | List: |
| References | |
| CEN-157(A)(NP), CEN-157(A)(NP)-A02, CEN-157(A)(NP)-A2, NUDOCS 8107300136 | |
| Download: ML20009F202 (13) | |
Text
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Arkansas Nuclear Orn - Unit 2 k
Docket 50-368 CEN-157(A)-NP Amendment 2-NP Response to Questions on Documents Supporting The ANO-2 Cycle 2 License Submittal
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July 1981 Combustion Engineering, Inc.
Nuclear Power Systems Power Systems Group Wir.dsor, Connecticut 06095 81073OO 8
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t LEGAL NOTICE THIS REPORT WAS PREPARED AS AN ACCOUNT OF WORK SPONSORED BY COMBUSTION ENGINEERING, INC. NEITHER COMBUSTION ENGINEERING NOR ANY PERSON ACTING ON ITS BEHALF:
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MAKES ANY WARRANTY OR REPRESENTATION, EXPRESS OR IMPLIED INCLUDING THE WARRANTIES OF FITNESS FOR. A PARTICULAR PURPOSE OR MERCHANTABILITY, WITH RESPECT TO THE ACCURACY, COMPLETENESS, OR USEFULNESS OF THE INFORMATION CONTAINED IN THIS REPORT, OR THAT THE USE OF ANY INFORMATION, APPARATUS, METHOD, OR PROCESS DISCLOSED IN THIS REPORT MAY NOT INFRINGE PRIVATELY OWNED HIGHTS;OR B. ASSUMES ANY LIABILITIES WITH RESPECT TO THE USE OF,OR FOR DAMAGES RESULTING FROM THE USE OF, ANY INFORMATION, APPARATUS, METHOD OR PROCESS DISCLOSED IN THIS REPORT.
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ABSTRACT ThisamendmenttoCEN-157(A)-P,-NP, amendment 2,isanexpansionofthe previously supplied answers to questions 492.15 and 492.16. The first provides the reason for a change in the numerical value of the power uncertainty factor E from that reported in CEN-143(A)-P, -NP to that cited in recent discussions between the NRC staff and C-E.
The second provides a discussion of the method of combining uncertainties to generate the CPC parameter BERRl.
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Table of Contents Legal flotice i
Abstract 11 Table of Contents iii Introduction 2
Supplement to Answer to Question 492.15 3
Supplement to Answer to Question 492.16 5
References 8
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.n INTRODUCTION The procedure for incorporating the power uncertainty inte the online protection system for the second cycle of Arkansas Nuclear One Unit 2 has been discussed by C-E and the NRC staff in both formal and informal sessions. Some of the informal oral discussions resulted in identifying a difference between the value of the power uncertainty factor E reported in CEN-143(A)-P, -NP (Reference 1) and that included in the online protection system.
In this amendment to CEN-157(A)-P, -NP, (Reference 2) the expansion of the answer to question 492.15 provides the reason for this change. Other oral discussions asked for more detailed explanations of the method for incorporating uncertainties into BERRl. The expansion of the answer to question 492.16 provides the required information. The materials described here are supplements to the answers provided in Reference 2, not replacements for them.
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Supplement to Response to NRC Question 492.15 Question 492.15 How is the value of power uncertainty factor of[
^]obtained for DNBR calculation?
Supplement to Response The value of the algorithm uncertainty factor (E) in CEN-143(A)-P has been changed.
The new value which is installed in the CPC software is[
[j.
The value of[
]is the 95/95 one sided tolerance factor determined from the distribution of the ratio of CETOP-2 to CETOP-D overpower margins (see Figure S-1).
The change in the E value is due to the following reason:
The CETOP2 code is written to use the hot channel peaking factor (hot channel pceer/ core average power) as input.
In the original analysis this input was used and the CETOP2 vs. CETOP-0 analysis yielded
'of the CPC module interfaces [it w'as discovered that the CPC power a 95/95 tolerance factor of l
During a quality assurance review algorithm calculates a[
jpeaking factor, rather than the {
]
4 peaking factor, for use in the static DNBR calculation. The [
] peaking factor is[
lthanthe[
]peakingfactor.
This input discrepancy was discovered late in the software design process and thet efore an algorithm change to (orrect the discrepancy was not feasible.
Instead, the uncer_tainty arsessment was repeated for CETOP2 with the input changed to Jtobe consistent with the input to the on-line algorithm.
The result of the new analysis was that the error distribution shifted by almost
[
] reflects the actual CETOP-2 on-fine algor [ithm perfonnance
[
The new value of[to CETOP-D.
relative The value for E in the CPC data base for ANO-2 Cycle 2 is[
[].
However, the CETOP2 to CETOP-D[
-)
[ included in the[.
- 1. This error distribution was' I Wow w
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_c Supplement to Response to f1RC Question 492.16 Question 492.16 (A-17)
What is the value of the addressable DNBR uncertainty factor, BERR1, used in the calculation of heat flux at full power?
Supplement to Response The general fomula of BERR1 is defined in equation (1)
P)
- P2 3
4 (1)
- P
- P BERR1
=
Where: P) composite DilB modelling uncertainty
=
state parameter fluctuation and computer processing P
=
2 uncertainties startup test acceptance band uncertainty P
=
3 CETOP2/CETOP-D correction factor P
=
4 P1 combines the DNB modelling and the online measurement uncertainty components.
Note that the DNB modelling uncertainty also includes the measurement uncertainties of the state parameters: s.ystem pressure. core inlet temnarature and coolant flow.
1+(Ytotal + kStotal)
(2)
P)
=
- (I - CECOR)'~ CECOR = [
]
(3)
Where: Ytotal
- DNS-model 1/2 (4) kStotal =,(kSDNB-model) + (kS
- SENS1) + (D )
r CECOR p
a s
Where: SENS1
=[.
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3 D
[
]
p CECOR, SENSl and D, equation (4) becomes With appropriate values of' kS S
p DNB-model' 2
kS total *d (b
) + (E'~
3 + (!
I 2
u KS
=[
]
(5) total Therefore, P) = 1 +[
3=[
]
(6')
+ Consistent with ANO-2 Cycle 1 methodology
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deterministically combines Y), Y, Y ' 4 5
and Y In general, P2 2
3 Where:
Y)
=
Y 2
Y 3
Y
=
4 Y
5 However,since5),Y and Y have already been implicitly accounted for, the 3
4 expression for P is simplified to:
2
- SENS2) * (1 + Y
- b "3
(
P2 * (I + Y2 5
Where:
SENS2
=[
.I SENS5
=[
]
and SEN5, P is evaluated as follows:
With appropriate values of Y, SENS2, Y5 2
2 P2 * (I d l) * (I + b'
])
P
[
]
(8) 2 P
combines Y '
and Y "9
- "9 3
6 7
8 P3=1+
(Y ) + (Y )
+ (Y )
(9) 6 7
8 A
Where:
Y 6
Y,
=
Y 8
With appropriate values of Y, Y7 and Y, P is evaluated as 6
8 3
+
Consistent with ANO-2 Cycle 1 methodology
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]
(10)
P
=
3 Explanation of P in BERR1 calculation 4
[
]=
(11)
P
=
4 The value of [
] is the value of E (CETOP2 algorithm penalty factor).
This is the final value included in the CPC software data base previously
- report as [
] in CEN-143(A)-P. (Reference 1)
This factor accounts for the difference between CETOP2 and CETOP-D.
Since this difference has already been accounted for both in the simulation of DNB modelling uncertainty (Pl) and the CPC software (Reference 3, equations 4.4-13 and 14),
this factor must be. included to eliminate double accounting.
and P evaluated via equations Using equation (1) and values of P), P, P3 4
2 (6), (8), (10) and (11) respectively, we have
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REFEREllCE
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1.
CEN-143(A)-P,-ftP, CPC/CEAC Software Modifications for Arkansas
- Nuclear One - Un.t 2," December 1980.
2.
" Response to Questions on Documents Supporting the ANO-2 Cycle 2 License Submittal," CEN-157(A)-P, April 1981, CEN-157(A)-P Amendment 1 P, June 1981.
3.
CEN-147(S)-P, " Functional Design Specification for a Core Protection Calcultor: Response to NRC Question 221.18 and 221.20," Jansary,19a!.
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