ML15274A475
| ML15274A475 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 09/29/2015 |
| From: | AREVA |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML15274A484 | List: |
| References | |
| L-MT-15-065, TAC MF5002 ANP-3435NP, Rev. 0 | |
| Download: ML15274A475 (19) | |
Text
L-MT-1 5-065 ARE VA Report ANP-3435NP Non-Proprietary ARE VA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR Revision 0 August 2015 Note: As discussed with NRC Staff (on September 28, 2015), the results of AREVA Reports ANP-3435P and ANP-3435NP (collectively referred to as ANP 3435P/NP) may be affected by a developing condition report associated with the AREVA core depletion code (MICROBURN-B2) that generated certain inputs for ANP-3435P/NP. Specifically, the decay ratios and peak cladding temperatures for the Two Recirculation Pump Trip cases reported in Section 2.2 will be increased. Figures 32-1 thr~ough 32-3 may have to be revised. AREVA has confirmed that this condition has no bearing on the methodology described in ANP-3435P/NP, but it may adversely affect the resultsir Therefore, to be responsive to the NRC RAIs, Enclosures 5 and 6 are provided to illustrate the methodology and the magnitude of margin to acceptance criteria, with the understanding that a revision to ANP-3435P/NP will be issued when the condition report is resolved and revised analyses are completed.
- 18. pages follow
Contro~led Document A
.AR EVA ANP-3435NP Revision 0 AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR August 2015 (c) 2015 AREVA Inc.
Controlled Document AREVA Inc.
ANP-3435NP Revision 0 Copyright © 2015 AREVA Inc.
All Rights Reserved
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page Nature of Changes Item Page Description and Justification
- 1.
All This is the initial issue AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 0 MNGP EFW LAR Page ii Contents 1.0 Introduction.................................................................................. 1-1 2.0 RAIs and Responses....................................................................... 2-1
2.1 RAI-8
Mitigated ATWSI Calculations.............................................. 2-1
2.2 RAI-32
2RPT ATWS.............................................................. 2-10 Tables Figures Figure 8-1 Core Inlet Subcooling Versus Time For Various Operator Intervention Times.....2-3 Figure 8-2 Hot Bundle Inlet Flow Versus Time For Various Operator Intervention Times.....
2-3 Figure 8-3 Hot Bundle Power Versus Time For Various Operator Intervention Times.......... 2-4 Figure 8-4 Clad Temperature Versus Time For Various Operator Intervention Times.......... 2-4 Figure 8-5 Peak Clad Temperature Versus Operator Intervention Time......................... 2-5 Figure 8-6 Gap Conductance Effect on Peak Clad Temperature Versus Operator Intervention Time....................................................................... 2-7 Figure 8-7 Orifice Loss Coefficient Effect on Peak Clad Temperature Versus Operator Intervention Time....................................................................... 2-7 Figure 8-8 [
] Effect on Peak Clad Temperature Versus Operator Intervention Time....................................................................... 2-8 Figure 32-1 Bundle Power Versus Time For [
].......................... 2-11 Figure 32-2 Bundle Inlet Flow Versus Time For [
]...................... 2-12 Figure 32-3 Clad Temperature Versus Time For [
]..................... 2-12 AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 0 MNGP EFW LAR Page iii Nomenclature Acronym Definition 2RPT 2 Recirculation Pump Trip ATWS Anticipated Transient Without Scram ATWSi ATWS with instability BOO Beginning-of-Cycle BWR Boiling Water Reactor CPR Critical Power Ratio DBA Design Basis Accident EFW Extended Flow Window EOC End-of-Cycle EOIII Enhanced Option IIl (Stability)
EPU Extended Power Uprate MELLLA Maximum Extended Load Line Limit Analysis MELLLA+
Maximum Extended Load Line Limit Analysis Plus MNGP Monticello Nuclear Generating Plant TTWBP Turbine Trip with Bypass AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 0 MNGP EFW LAR Page 1-1 1.0 Introduction In Reference 1, Northern States Power Company - a Minnesota corporation, doing business as Xcel Energy, submitted a license amendment request (LAR) for the Monticello Nuclear Generating Plant (MNGP). The application was supplemented by Reference 2. The amendment would revise the Technical Specifications and approve certain AREVA analytical methods to support plant operation in the expanded power-flow domain described as the Extended Flow Window (EFW).
The U.S. Nuclear Regulatory Commission (NRC) staff in the Reactor Systems Branch (SRXB) and Nuclear Performance and Code Review Branch (SN PB) has reviewed the application and concluded that additional information is necessary to complete its review. Draft Requests for Additional Information (RAI) were provided as an attachment to Reference 3. AREVA responses to all of these RAI except RAI-8 and RAI-32 were documented in Reference 4. The RAI and the AREVA responses for RAI-8 and RAI-32 are attached.
The revised analysis of Anticipated Transient Without Scram - Instability (ATWSi) described herein should be recognized as the licensee's analysis of record supporting the proposed amendment to allow operation in the EFW domain. [
]
These responses are provided so Xcel Energy can provide a complete set of responses to the NRC by combining the AREVA responses with the responses being prepared by Xcel Energy.
References
- 1.
License Amendment Request for ARE VA Extended Flow Window, October 3, 2014, MNGP L-MT-14-044, ML14283A119.
- 2.
License Amendment Request for AREVA Extended Flow Window Supplement to Response to NRC Staff Questions (TAC No. MF5002), January 9, 2015, MNGP L-MT-14-103, ML15022A165 and ML15022A167.
- 3.
Monticello Nuclear Generating Plant - Request for Additional Information (SRXB/SNPB) re:
AREVA Extended Flow Window Licence Amendment Request (TAC No MF5002) - email from Terry Beltz (NRC) to Glenn Adams (Xcel Energy), August 5th, 2015.
- 4.
ANP-3434P Revision 1, ARE VA Responses to PA! from SRXB and SNPB on MNGP FEW LAR, ARE VA, August 2015.
AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-1 2.0 RAIs and Responses
2.1 RAI-8
Mitigated A TWSI Calculations A TWASI calculations in the Monticello LAR are for unmitigated (i. e., no operator actions) assumptions.
a) Provide realistic Anticipated Transient Without Scram with Instability (A TWSI) calculations under the expected conditions crediting operator actions. Provide sensitivity results for later operator action time.
b) Provide a discussion of uncertainty treatment (e.g., hGap, inlet friction).
c) Describe the methodology used by AISHA to excite the oscillation when the decay ratio (DR) is close to 1.0.
ARE VA Response a) Provide realistic Anticipated Transient Without Scram with Instability (A TWSI) calculations under the expected conditions crediting operator actions. Provide sensitivity results for later operator action time.
The case that produced the maximum clad temperature excursion without operator action was repeated while crediting the operator action of lowering the water level. As is demonstrated below, the operator action [
] and the transient is demonstrated to be uneventful. The operator action was delayed by increasing time periods in a series of runs to examine the sensitivity of the action timing. It was found that a delayed action [
The sensitivity runs were made with operator action initiated at 90 seconds and at larger values with incremental steps of 10 seconds. [
] The sensitivity to operator action timing is illustrated in the following figures. In some of the figures, only the results of representative runs are shown to avoid crowding of data so the trends are more clearly seen.
Two modifications were made to the original runs in order to properly model the mitigated cases. [
AREVA Inc.
ControDled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-2
]
Figure 8-2 shows the inlet mass flow rate as a function of time for several cases with differing operator action times. [
Figure 8-3 shows the limiting bundle power for the cases represented in Figure 8-2.
Figure 8-4 shows the clad temperature excursion for selected cases with differing operator action timing.
[
]
Figure 8-5 depicts the peak clad temperature that is reached in the different simulations with different operator action timing. The figure shows clearly that [
AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-3 Figure 8-1 Core Inlet Subcooling Versus Time For Various Operator Intervention Times Figure 8-2 Hot Bundle Inlet Flow Versus Time For Various Operator Intervention Times AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-4 Figure 8-3 Hot Bundle Power Versus Time For Various Operator Intervention Times Figure 8-4 Clad Temperature Versus Time For Various Operator Intervention Times AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-5 Figure 8-5 Peak Clad Temperature Versus Operator Intervention Time AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW [AR ANP-3435NP Revision 0 Page 2-6 b) Provide a discussion of uncertainty treatment (e.g., hGap, inlet friction).
The mitigated cases as described in item a) above were performed again while varying certain parameters. These parameters have been identified as being of higher importance and also represent a higher level of calculational uncertainty. These parameters include The gap conductance was [
The inlet orifice resistance was [
- [
]
]
]
As shown in Figure 8-6 through Figure 8-8, the effect of these parameter variations on the Peak Clad Temperature (PCT) is [
]
It is important to note that the range of parameter variation imposed on the simulation is larger than the uncertainty for these parameters.
AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-7 Figure 8-6 Gap Conductance Effect on Peak Clad Temperature Versus Operator Intervention Time Figure 8-7 Orifice Loss Coefficient Effect on Peak Clad Temperature Versus Operator Intervention Time AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-8 Figure 8-8 [
] Effect on Peak Clad Temperature Versus Operator Intervention Time AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-9 c) Describe the methodology used by AISHA to excite the oscillation when the decay ratio (DR) is close to 1.0O.
[
]
References for RAI-8 8-1.
ANP-3274P Revision 1, "Analytical Methods for Monticello ATWS-l," July 2014.
AREVA inc,
ControH~ed Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 0 MNGP EFW LAR Page 2-10
2.2 RAI-32
2RPT ATWS The A TWASI analysis of record in the LAR is Turbine Trip with Bypass (TTWBP). When operator actions are credited, the TTIABP does not show significant power oscillations and the limiting A TVVS/ transient becomes the 2RPT with failure to scram.
Provide the results of 2RPT event with failure to scram. Describe the basis for boundary conditions and operator actions assumed for the analysis.
AREVA Response The Two Recirculation Pump Trip (2RPT) differs from the Turbine Trip With Bypass (TTWBP) event in that turbines are not isolated and the steam flow to the feedwater heaters is not interrupted. The 2RPT transient results in a much smaller feedwater temperature transient, as the feedwater temperature decreases to a new equilibrium value determined by the final power level. [
AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SIRXB and SNPB on MNGP EFW [AIR ANP-3435NP Revision 0 Page 2-11
]
The results are shown in Figure 32-1 through Figure 32-3. Figure 32-1 shows the limiting bundle power as function of time, and Figure 32-2 shows the corresponding inlet flow rate. Figure 32-3 shows the peak powered rod clad temperature at different axial nodes. The maximum clad temperature of [
]
Figure 32-1 Bundle Power Versus Time For [
]
AREVA Inc.
Controlled Document AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR ANP-3435NP Revision 0 Page 2-12 Figure 32-2 Bundle Inlet Flow Versus Time For [
Figure 32-3 Clad Temperature Versus Time For [
]
m
]
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