LR-N08-0123, C.D.I. Technical Note No. 07-29NP, Revision 2, Limit Curve Analysis with ACM Rev. 4 for Power Ascension at Hope Creek Unit 1.

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C.D.I. Technical Note No. 07-29NP, Revision 2, Limit Curve Analysis with ACM Rev. 4 for Power Ascension at Hope Creek Unit 1.
ML081480509
Person / Time
Site: Hope Creek PSEG icon.png
Issue date: 05/31/2008
From: Teske M
Continuum Dynamics
To:
Office of Nuclear Reactor Regulation, Public Service Enterprise Group
References
4500400038, LR-N08-0123 CDI 07-29NP, Rev 2
Download: ML081480509 (13)
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LR-N08-0123 ATTACHMENT 3 Hope Creek Generating Station Facility Operating License NPF-57 Docket No. 50-354 Limit Curve Analysis with ACM Rev. 4 for Power Ascension at Hope Creek Unit 1 C.D.I. Technical Note No. 07-29NP, Revision 2

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information C.D.I. Technical Note No. 07-29NP Limit Curve Analysis with ACM Rev. 4 for Power Ascension at Hope Creek Unit 1 Revision 2 Prepared by Continuum Dynamics, Inc.

34 Lexington Avenue Ewing, NJ 08618 Prepared under Purchase Order No. 4500400038 for Nuclear Business Unit, PSEG Nuclear LLC Materials Center, Alloway Creek Neck Road Hancocks Bridge, NJ 08038

. Approved by 0411t4 Alan J. Bilanin Prepared by Milton E. Teske May 2008

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information Table of Contents Section Page T able of Contents ..................................................................... i

1. Introduction ............................................................................ 1
2. A pproach ........................ .... ............................................. 2
3. L im it C urves ........................................................................... 4
4. References ............................................................................. 9

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information

1. Introduction During power ascension of Hope Creek Unit I (HC1), from Current Licensed Thermal Power (CLTP) to Extended Power Uprate (EPU), PSEG is required to monitor the dryer stresses at plant power levels that have not yet been achieved. Limit curves provide an upper bound safeguard against the potential for dryer stresses becoming higher than allowable, by estimating the not-to-be-exceeded main steam line pressure levels. In the case of HCI, in-plant main steam line data have been analyzed at CLTP conditions to provide steam dryer hydrodynamic loads [I].

A finite element model stress analysis has been undertaken on the CLTP loads [2]. These loads provide the basis for generation of limit curves to be used during HC1 power ascension.

Limit curves allow PSEG to monitor dryer stress levels, by comparing the main steam line pressure readings - represented in Power Spectral Density (PSD) format - with the upper bound PSD derived from existing in-plant data.

This technical note summarizes the proposed approach that will be used to track the anticipated stress levels in the HCI steam dryer during power ascension, utilizing Rev. 4 of the ACM [3].

Due to the limitations of the high pressure (HP) turbine being installed in the Fall 2007 outage, the Target Power Uprate (TPU) for at least the operating cycle between Fall 2007 and Spring 2009 will be limited to approximately 111.5% CLTP.

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information

2. Approach The limit curve analysis for HCI parallels the approach followed by Entergy Vermont'

. Yankee (VY) in its power uprate [4]. In the VY analysis, two levels of steam dryer performance criteria were described: (1) a Level I pressure level based on maintaining the ASME allowable.

alternating stress value on the dryer,. and (2) a Level 2 pressure level based on maintaining 80%

of the allowable alternating stress value on the dryer. Should Level 2 be reached or exceeded (under the rules discussed below), reactor power ascension was to be suspended until an engineering evaluation concluded that further power ascension was justified. Should Level I be reached or exceeded, reactor power was to be returned to a previously acceptable power level while an engineering evaluation was undertaken.

To develop the limit curves upon which Level 1 and Level 2 were based, VY calculated the stress levels in the dryer corresponding to the current plant acoustic signature, and then determined how much the acoustic signature could be increased while maintaining stress levels below the 13,600 psi stress fatigue limit. A Level I limit curve was then constructed by scaling up the current plant acoustic signature at each point along the frequency spectrum of interest by this overall factor. A Level 2 limit curve was produced in the same manner except at 80% of the fatigue limit, or 10,880 psi, arbitrarily selected by VY, to determine the overall factor. During power ascension, the Level 2 limit curve was reached at discrete frequencies at three power levels. In each case VY stopped the power ascension, determined the impact of the new acoustic signature on the dryer stresses, and developed revised Level 2 limit curves to use at higher power steps. Their Level 1 limit curve was never reached. The VY approach is summarized in [5].

HCJ steam dryer data and evaluations will be performed as required per Attachment 3 "Dryer Data Collection" (Test No. 101) of HC.OP-FT.ZZ-0004(Q), "Extended Power Uprate Power Ascension Testing" (PSEG).

The finite element analysis using the HCI CLTP data found a lowest/minimum alternating stress ratio of 3.11, as summarized in Table 1. The minimum stress ratios include the model bias and uncertainties for specific frequency ranges as suggested by the NRC [6]. The results of the ACM Rev. 4 analysis (based on Quad Cities Unit 2, or QC2, in-plant data) are summarized in Table 2 (a negative bias is conservative). Note that the standpipe excitation frequency in HCI is anticipated to be 118 Hz, and that the uncertainty determined around the QC2 excitation frequency of 155 Hz has been applied to the 116 to 120 Hz frequency interval.

The additional bias and uncertainties, as identified in [7 - 12], are shown in Table 3. SRSS of the uncertainties, added to the ACM bias, results in the total uncertainties shown in Table 4.

These uncertainties were applied to the finite element analysis, resulting in the minimum alternating stress ratio of 3.11.

Table 1. Alternating Stress Limit Summary ASME Code Stress Limit 13,600 psi (Level 1) 10,880 psi (Level 2)

Minimum Alternating 3.11 2.49 Stress Ratio 2

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information Table 2. Bias and uncertainty for ACM Rev. 4 (3)))1 Table 3. HCI additional uncertainties (with references cited)

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(3)))

Table 4. HC I total uncertainty (3)))

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information

3. Limit Curves Limit curves were generated from the in-plant CLTP strain gage data collected in May 2008 [13]. These data were filtered across the frequency ranges shown in Table 5 to remove noise and extraneous signal content, as suggested in [14]. The resulting PSD curve for each of the eight strain gage locations was then used to develop the limit curves, shown in Figures 1 to 4.

Level I limit curves are found by multiplying the CLTP main steam line pressure PSD traces by the square of the minimum alternating stress ratio, while the Level 2 limit curves are found by multiplying the CLTP PSD traces by 0.64 of the square of the minimum alternating stress ratio, as PSD is related to the square of the pressure. The minimum alternating stress ratio for Hope Creek is 3.11.

Table 5. Exclusion frequencies for HCI Frequency Interval (Hz) Exclusion Cause 0.0 to 2.0 Mean 59.8 to 60.2 60 Hz Line Noise 119.8 to 120.2 120 Hz Line Noise 179.8 to 180.2 180 Hz Line Noise 101.2 to 101.6 A Recirculation Pump 101.8 to 102.2 B Recirculation Pump 4

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information (3)))

Figure 1. Level 1 (black) and Level 2 (red) limit curves for main steam line A, compared against the base curves (blue) over the frequency range of interest: A upper strain gage location (top); A lower strain gage location (bottom).

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This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information (3)))1 Figure 2. Level I (black) and Level 2 (red) limit curves for main steam line B, compared against the base curves (blue) over the frequency range of interest: B upper strain gage location (top); B lower strain gage location (bottom).

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This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information (3)]

Figure 3. Level I (black) and Level 2 (red) limit curves for main steam line C, compared against the base curves (blue) over the frequency range of interest: C upper strain gage location (top); C lower strain gage location (bottom).

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This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information I((

(3)))

Figure 4. Level I (black) and Level 2 (red) limit curves for main steam line D, compared against the base curves (blue) over the frequency range of interest: D upper strain gage location (top); D lower strain gage location (bottom).

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This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information

4. References
1. Continuum Dynamics, Inc. 2007. Acoustic and Low Frequency Hydrodynamic Loads 'at CLTP Power Level on Hope Creek Unit I Steam Dryer to 200 Hz (Rev. 0). C.D.I."Report No. 07-18 (Proprietary).
2. Continuum Dynamics, Inc. 2007. Stress Assessment of Hope Creek Unit I Steam Dryer Based on Revision 4 Loads Model (Rev. 4). C.D.I. Report No. 07-17 (Proprietary).
3. Continuum Dynamics, Inc. 2007. Methodology to Predict Full Scale Steam Dryer Loads from In-Plant Measurements, with the Inclusion of a Low Frequency Hydrodynamic Contribution (Rev. 1). C.D.1. Report No. 07-09 (Proprietary).
4. Entergy Nuclear Northeast. 2006. Entergy Vermont Yankee Steam Dryer Monitoring Plan (Rev. 4). Docket 50-271. No. BVY 06-056. Dated 29 June 2006.
5. State of Vermont Public Service Board. 2006. Petition of Vermont Department of Public Service for an Investigation into the Reliability of the Steam Dryer and Resulting Performance of the Vermont Yankee Nuclear Power Station under Uprate Conditions.

Docket No. 7195. Hearings held 17-18 August 2006.

6. NRC Request for Additional Information on the Hope Creek Generating Station, Extended Power Uprate. 2007. TAC No. MD3002. RAI No. 14.67.
7. Szasz, G. 2007. Strain Gage Uncertainty Analysis. Email Dated 06 July 2007.
8. Continuum Dynamics, Inc. 2005. Vermont Yankee Instrument Position Uncertainty. Letter Report Dated 01 August 2005.
9. Exelon Nuclear Generating LLC. 2005. An Assessment of the Effects of Uncertainty in the Application of Acoustic Circuit Model Predictions to the Calculation of Stresses in the Replacement Quad Cities Units I and 2 Steam Dryers (Revision 0). Document No. AM-21005-008.
10. Continuum Dynamics, Inc. 2007. Finite Element Modeling Bias and Uncertainty Estimates Derived from the Hope Creek Unit 2 Dryer Shaker Test (Rev. 0). C.D.I. Report No. 07-27 (Proprietary).
11. NRC Request for Additional Information on the Hope Creek Generating Station, Extended Power Uprate. 2007. RAI No. 14.79.
12. NRC Request for Additional Information on the Hope Creek Generating Station, Extended Power Uprate. 2007. RAI No. 14.110.
13. Email from M. Trubelja, Structural Integrity Associates, Inc., 100% power data collected in the file named "HCI00noiseless_5_15_set3.dat" sent 15 May 2008.

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This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information

14. Structural Integrity Associates, Inc. 2007. Hope Creek Main Steam Line Strain Gage Data Reduction. File No. HC-30-301.

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