L-MT-15-081, ANP-3435NP, Revision 1, Areva Responses to RAI-8 and RAI-32 from Srxb and Snpb on MNGP EFW Lar.

ANP-3435NP, Revision 1, Areva Responses to RAI-8 and RAI-32 from Srxb and Snpb on MNGP EFW Lar.

ML15345A408
Person / Time
Site:	Monticello
Issue date:	12/08/2015
From:	AREVA
To:	Office of Nuclear Reactor Regulation
Shared Package
ML15345A414	List: L-MT-15-081, ANP-3435NP, Revision 1, Areva Responses to RAI-8 and RAI-32 from Srxb and Snpb on MNGP EFW Lar. ML15345A407
References
L-MT-15-081, TAC MF5002 ANP-3435NP, Rev. 1
Download: ML15345A408 (24)

Text

L-MT-1 5-081 Enclosure 2 AREVA Report ANP-3435NP Non-Proprietary ARE VA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR Revision 1 November 2015 19 pages follow

Contro~led Document A

ARE VMA AN P-3435N P Revision 1 AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR November 2015 (c) 2015 AREVA Inc.

Controlled Document AREVA Inc.

ANP-3435NP Revision 1 Copyright © 2015 ARE VA Inc.

All Rights Reserved

ControD~ed Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Pagei Nature of Changes Item Pages Description and Justification

1. 1-1 to 1-2 Added Section 1.1 to discuss MICROBURN-B2 issues.

2. 2-1 to 2-12 Updated Sections 2.1 and 2.2 to correct for MICROBURN-B2 issues.

AREVA Inc.

ControD~ed Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page ii Contents 1.0 Introduction................................................................................... 1-1 1.1 Description of MICROBURN-B2 Issues............................................ 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 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 [" I ...................... 2-11

.Figure 32-3 Clad Temperature Versus Time For [ ]...................... 2-12 AREVA Inc.

Controlled Document AREVA Responses RAI-32 from to RAI-8 SRXB and SNPBandon ANP-3435NP Revision 1 MNGP EFW LAR Page iii Nomenclature Acronym Definition 2RPT 2 Recirculation Pump Trip ATWS Anticipated Transient Without Scram ATWSi ATWS with instability BOC 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 Ill (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.

ControH~ed Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 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 (SNPB) 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 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. [

]

Following submittal of Revision 0 of this document, two issues have been discovered within MICROBURN-B2. A description of these issues is found in the following section, and the results in Section 2.0 have been updated with corrected results for these issues.

These responses are provided so Xcel Energy can provide a complete set of responses to the NRC by combining the ARE VA responses with the responses being prepared by Xcel Energy.

1.1 Description of MICROBURN-B2 Issues The identified issues within MICROBURN-B2 are described in detail below, but it is noted that both are only a concern in regard to low flow calculations.

The first issue that was identified within MICROBURN-B2 was that at some low flow conditions (i.e.,

below 50% rated core flow), the MICROBURN-B2 code hydraulic convergence might not be sufficient to ensure the accuracy of the resulting solutions.

A new version of the MICROBURN-B2 code has been issued with a revised low flow convergence scheme that addresses this non-convergence issue. This new version of the code has been used in the revised calculations discussed later in this document.

The second issue within MICROBURN-B2 identifies that the current implementation of the void quality correlation used within MICROBURN-B2 includes by default [ ]. Investigations AREVA Inc.

Controlled Document AREVA Responses RAI-32 from to RAI-8 SRXB and SNPBandon ANP-3435NP Revision 1 MNGP EFW LAR Page 1-2 that have been carried out revealed that the correlation produces some potentially non-physical results at very low mass fluxes and high flow qualities, which is part of the reason for the implementation of the

[ ] into the correlation in MICROBURN-B2. This default behavior for MICROBURN-B2 was implemented in 2011.

The non-physical behavior is inherent in the formulation of the correlation and is not an implementation issue within the MICROBURN-B2 code. Investigation has determined that the correlation behaves in an expected manner for the following range of conditions*:

All versions of the MICROBURN-B2 code since 2011 have included a default [

]. While this appears to have mitigated the correlations non-physical behavior it has been determined [

Revised calculations were performed eliminating the [" ] with an existing MICROBURN-B2 input. The analyses were then reviewed to confirm that all cases fall within [

] behavior is as expected.

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 ARE VA 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 (TAO No MF5002) - email from Terry Beltz (NRC) to Glenn Adams (Xcel Energy), August 5th, 2015.

4. ANP-3434P Revision 1, ARE VA Responses to RAI from SRXB and SNPB on MNGP EFW LAR, AREVA, August 2015.

• The range of applicability has been defined in a conservative manner. Falling outside this range does not mean that the void-quality correlation will provide a non-physical result; instead it indicates that the potential exists.

Analyses inside of this range of conditions produce the expected result.

AREVA Inc.

ControD~ed Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page 2-1 2.0 RAIs and Responses

2.1 RAI-8

Mitigated A TWSI Calculations A TWSI calculationsin the Monticello MAR are for unmitigated (i.e., no operatoractions) assumptions.

a) Provide realisticAnticipated Transient Without Scram with Instability (A TWSI) calculationsunder the expected conditions crediting operatoractions. Provide sensitivity results for later operator action time.

b) Provide a discussion of uncertaintytreatment (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 realisticAnticipated Transient Without Scram with Instability (A TWSI) calculations under the expected conditions crediting operatoractions. 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.

Contronled Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR 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.

Cotrl dDoumn AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR 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.

Con1:roI!ed Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR 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.

I onr~e Documentf AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page 2-5 Figure 8-5 Peak Clad Temperature Versus Operator Intervention Time AREVA Inc.

ControDled Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page 2-6 b) Provide a discussion of uncertaintytreatment (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 (POT) 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.

Document AREVA Responses to RAI-8 and AN P-3435NP RAI-32 from SRXB and SNPB on Revision I MNGP EFW LAR 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.

Cont rolleKd Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page 2-8 Figure 8-8 [ ] Effect on Peak Clad Temperature Versus Operator Intervention Time AREVA Inc.

Contro~led Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page 2-9 c) Describe the methodology used by AISHA to excite the oscillation when the decay ratio (DR) is close to 1.0.

[

]

References for RAI-8 8-1. ANP-3274P Revision 1, "Analytical Methods for Monticello ATWS-I," July 2014.

AREVA Inc.

Controlied Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page 2-10

2.2 RAI-32

2RPT ATWS The A TWSI analysis of record in the LAR is Turbine Trip with Bypass (TTWBP). When operatoractions are credited, the TTWBP does not show significantpower oscillations and the limiting A TWSI 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 operatoractions 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. [

]

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 AREVA Inc.

Controlled Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW LAR Page 2-11 powered rod clad temperature at different axial nodes. The maximum clad temperature of ["

]

Figure 32-1 Bundle Power Versus Time For [ ]

Figure 32-2 Bundle Inlet Flow Versus Time For [ ]

AREVA Inc.

Controg~ed Document AREVA Responses to RAI-8 and ANP-3435NP RAI-32 from SRXB and SNPB on Revision 1 MNGP EFW [AR Page 2-12 Figure 32-3 Clad Temperature Versus Time For [ ]

AREVA Inc.

L-MT-1 5-081 Enclosure 3 ARE VA Affidavit 3 pages follow

AFFIDAVIT STATE OF WASHINGTON )) ss.

COUNTY OF BENTON )

1. My name is Alan B. Meginnis. I am Manager, Product Licensing, for AREVA Inc. and as such I am authorized to execute this Affidavit.

2. I am familiar with the criteria applied by AREVA to determine whether certain AREVA information is proprietary. I am familiar with the policies established by ARE VA to ensure the proper application of these criteria.

3. I am familiar with the ARE VA information contained in the report ANP-3435P, Revision 1, "AREVA Responses to RAI-8 and RAI-32 from SRXB and SNPB on MNGP EFW LAR," dated November 2015 and referred to herein as "Document." Information contained in this Document has been classified by AREVA as proprietary in accordance with the policies established by AREVA for the control and protection of proprietary and confidential information.

4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by AREVA and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.

5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence ,with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR,2.390. The information for which withholding from disclosure is

• requested qualifies under 10 CFR 2.390(a)(4) "Trade secrets and commercial or financial information."

6. The following criteria are customarily applied by AREVA to determine whether information should be classified as proprietary:

(a) The information reveals details of AREVA's research and development plans and programs or their results.

(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, .in time or resources, to design, produce, or market a similar product or service.

(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for AREVA.

(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for ARE VA in product optimization or marketability.

(e) The information is vital to a competitive advantage held by AREVA, would be helpful to competitors to AREVA, and would likely cause substantial harm to the competitive position of AREVA.

The information in the Document is considered proprietary for the reasons set forth in paragraphs 6(b), 6(d) and 6(e) above.

7. In accordance with AREVA's policies governing the protection and control of information, proprietary information contained in this Document have been made available, on a limited basis, to others outside AREVA only as required and under suitable agreement providing for nondisclosure and limited use of the information.

8. AREVA policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.

9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.

SUBSCRIBED before me this ]*

day of ...f)-d' 2015.

NOTARY PUBLIC, STATE OF WASHI TON MY COMMISSION EXPIRES: 1/14/20 16