ML053180374
| ML053180374 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 03/31/2005 |
| From: | Colby M, Pearson G General Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| DRF 0000-0036-7307, LCR H05-01, LR-N05-0329 NEDO-33179-R1 | |
| Download: ML053180374 (12) | |
Text
Attachment 6 LR-N05-0329 LCR H05-01 NEDO-331 79-RI BSP Evaluation Report MELLLA Backup Stability Protection Evaluation for Hope Creek Cycle 14 at CPPU Conditions
[rhe CPPU cycle in this report is referred to as Cycle 14 for report generation purposes only. Cycle 14 will not be the EPU implementation cycle.]
GE Nuclear Energy General Electic Company 175 CurtnerAvenue, San Jose CA 95125 NEDO-33179-RI DRF 0000-0036-7307 Class I March 2005 BSP Evaluation Report MELLLA Backup Stability Protection Evaluation for Hope Creek Cycle 14 at CPPU Conditions Prepared by:
Approved by:
Gregory Pearson Mark tolby, Te(mi Lead Fuel Engineering Services, GNF-A
NEDO-33179-RI Non-Proprietary Notice This is a non-proprietary version of the document NEDC-33179P-RI, which has the proprietary information removed. Portions of the document that have been removed are indicated by an open and closed bracket as shown here ((
Disclaimer The only undertakings of the GE respecting information in this document are contained in the contract between the company receiving this document and GE. Nothing contained in this document shall be construed as changing the applicable contract. The use of this information by anyone other than a customer authorized by GE to have this document, or for any purpose other than that for which it is intended, is not authorized. With respect to any unauthorized use, GE makes no representation or warranty, and assumes no liability as to the completeness, accuracy or usefulness of the information contained in this document, or that its use may not infringe privately owned rights.
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NEDO-33 179-RI BACKGROUND The stability Interim Corrective Actions (ICA) published by the BWR Owners' Group in Reference I can be summarized as guidance for reactor operation in regions of the power/flow domain where the margin to thermal hydraulic instability has been reduced. The ICA regions were based upon empirical evaluations and experience of BWR operation, and were described in terms of relative core flow and flow control lines (rod lines). The regions were not based upon specific analyses and hence do not provide constant margin to potential thermal hydraulic instability events. In Reference 2, the BWR Owners' Group recommended that plants review the applicability of the generic ICA regions on their respective core designs based on the fact that
"...aggressive core design changes may have reduced stability margin". Reference 3 describes the method that GE proposed for licensees to review the applicability of their ICA regions.
INTRODUCTION The objective of this evaluation is to demonstrate the stability performance of a mixed core of SVEA 96+ and GE14 fuel at a Constant Pressure Power Uprate (CPPU) condition of 115% of the current licensed thermal power (CLTP) with operation in the Maximum Extended Load Line Limit Analysis (MELLLA)l domain and no change in the normal maximum operating pressure.
The evaluation is performed for a Hope Creek core containing 348 SVEA 96+ fuel assemblies and 416 GE14 fuel assemblies. The quantity of each fuel type may vary in the actual Cycle 14 core. The Backup Stability Protection (BSP, Reference 3) regions are determined at a bounding feedwater temperature for this demonstration. The BSP Scram Region I and Controlled Entry Region 11 are established using ODYSY stability acceptance criterion as shown in Figure 1. The base BSP region boundary intercepts are the same as the ICA region boundary intercepts on the natural circulation line (NCL) and the highest flow control line (HFCL). If the ODYSY calculations determine that the BSP regions are larger than the corresponding ICA regions, then the larger BSP regions are used for stability monitoring in the event that the Oscillation Power Range Monitor (OPRM) system is declared inoperable.
The MELLLA Boundary Line in the power/flow map represents a generically developed load line for Hope Creek. The actual plant operating load line is expected to vary through the cycle and from cycle to cycle and may not follow this MELLLA boundary line.
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NEDO-33 179-RI ANALYSIS The following application procedure is designed to produce a conservative calculation of the BSP stability regions on the MELLLA power/flow map as shown in Figure 2, that have the potential for reactor instability, considering all manual BSP requirements (Reference 3). The procedure for the decay ratio (DR) calculations is summarized as follows:
- 1. Obtain accurate cycle and exposure dependent inputs from the core simulator. Rodded depletions are used in these calculations. The core and channel DR calculations are performed for a number of exposure points through the cycle to determine the limiting exposure.
- 2. Perform DR calculations at the limiting exposure along the HFCL and the NCL to search for the bounding state points. Table I outlines the key assumptions used in this analysis.
- 3. Plot the decay ratio results on the stability criterion map (see Figure 1). Use a linear interpolation scheme along the HFCL and along the NCL to determine the power/flow state points that produce core decay ratios that satisfy the acceptance criterion shown in Figure 1. The power/flow state points that meet this acceptance criterion define the region boundary intercepts on the HFCL and the NCL.
- 4. Use the following Generic Shape Function (GSF) to construct the region boundary:
PB where:
P = percent rated power at a point on region boundary PA = percent rated power at point A (HFCL) 4 of 11
NEDO-33 179-RI PB = percent rated power at point B (NCL)
W = percent rated core flow WA = percent rated core flow at point A WB = percent rated core flow at point B.
Table 1 Key Assumptions for BSP Regions Calculation Application Assumptions Xenon concentration
- For Region I on the NCL, constant Xenon at rated operating condition
- For Region II on the NCL, no Xenon
- For Region I on the 1-FCL, constant Xenon at rated operating condition
- For Region I, constant feedwater temperature at rated (FY VI )
operating condition
- For Region I1, equilibrium feedwater temperature at off-rated operating condition 5 of 1l
NEDO-33 179-RI RESULTS AND DISCUSSION Core and channel DR calculations are performed at the base BSP Scram Region NCL and HFCL boundary points for a number of exposure points through the cycle to determine the limiting exposure for both the NCL and the HFCL. The results are calculated based on a verified ODYN base deck prepared for the Hope Creek CPPU and is acceptable for the Cycle 14 evaluation. For Hope Creek Cycle 14 operation, the limiting exposure occurs at BOC based on limiting highest channel DR and at EOC-1234 MWD/ST (11,000 MWD/ST) based on limiting core DR for both BSP Scram Region boundary points as shown in Table 2. Therefore, the determination of the BSP boundary intercepts on the NCL and the HFCL for the Scram Region I and the Controlled Entry Region 11 is performed at BOC and 11,000 MWD/ST.
Proposed BSP Regions for Cycle 14 The computed DR results at the BOC bounding state points Al, B1, A2 and B2 and the 11,000 MWD/ST bounding state points Al', B1', A2' and B2' on the NCL and the HFCL for MELLLA operation are shown in Figure 1 and Table 3. The base BSP Region HFCL and NCL boundary points A,-ICA, B1-4CA, A2-4CA and B2-4CA are also shown in Table 3. The calculated BSP state point Al on the HFCL is greater than Al' and Al-ICA and therefore becomes the proposed BSP scram region boundary intercept on the HFCL. Because the point sets B, and B,', A2 and A2', and B2 and B2' are located inside the corresponding base BSP boundary points B -ICA, A2-ICA and B2-ICA along the HFCL or the NCL on the power/flow map, the calculated BSP region boundary intercepts are replaced by the corresponding base BSP boundary points B1-ICA, A2-ICA and B2-ICA, respectively, in accordance with Reference 3. Hence, the proposed BSP scram region boundary intercepts are Al and B1-4CA and the proposed BSP controlled entry region boundary intercepts are the base BSP boundary points A2-4CA and B2-ICA, as shown in Table 3.
The proposed BSP region boundaries are established using the GSF as shown in Figure 2 at the bounding feedwater temperature (4097F). All calculated BSP region boundary intercepts based on the BOC ODYSY DR results are shown in Figure 2 for comparison.
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NEDO-33 179-RI Table 2 Decay Ratios of BSP Scram Region NCL and HFCL Boundary Points as a Function of Cycle Exposure at a Bounding Feedwater Temperature of 409°F Power/Flow Point Exposure Core Highest Feedwater (Case Name)
Rated Rated (MWD/ST)*
DR Channel DR Temperature Power Flow (OF)
-- ;___-_-_- Scram`Region'l,'NCLlPoints
((
0.577 0.017 409.0 T
I I
0.567 0.024 409.0 T 1 1
1 0.585 0.007 409.0 0.577 0.029 409.0 0.634 0.008 409.0 0.629 0.080 409.0 0.564 0.314 409.0 0.426 0.416 409.0 0.269 0.447 409.0 0.236 0.464 409.0 0.384 0.499 409.0 0.388 0.530 409.0 0.371 0.552 409.0
- ScramRegion'IHFClPoints 0.702 0.199 409.0 0.688 0.212 409.0 0.710 0.185 409.0 0.703 0.246 409.0 0.745 0.146 409.0 0.725 0.325 409.0 0.654 0.428 409.0 0.506 0.484 409.0 0.346 0.541 409.0 0.207 0.576 409.0 0.373 0.627 409.0 0.411 0.672 409.0 ll 0.405 0.708 409.0
- EOC exposure for the BSP analysis is 12,234 MWD/ST.
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NEDO-33 179-RI Table 3 ODYSY Decay Ratio Results at Bounding Feedwater Temperature (409TF) for determining MELLLA BSP Regions Power/Flow Rated Rated Exposure Core DR Highest Feedivater Point Power Flow MWD/ST Channel Temperature
_%)
(%)
DR (7F)
.'Scram'Region1, NCL Point L
0.427 0.653 409.0 0.795 0.183 409.0
'Controlied iEntry INCL'Points I 0.457 0.638 329.2
'Srailgi0.792 0.078 334.3 Scram'Region'l,'HFCL Point 0.389 0.670 409.0 0.795 0.196 409.0
-.Controlled ]ntryRegionI,HFCL'Point 0.492 0.627 364.1 0.794 0.069 364.3 8 of 11
NEDO-33179-RI REFERENCES
- 1. "BWR Owners' Group Guidelines for Stability Interim Corrective Action," BWROG-94078, June 6, 1994.
- 2. "Review of BWR Owners' Group Guidelines for Stability Interim Corrective Action,"
BWROG-02072, November 20,2002.
- 3. "Backup Stability Protection (BSP) for Inoperable Option III Solution," GE to BWR Owners' Group Detect and Suppress 11 Committee, OG 02-0119-260, July 17, 2002.
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NEDO-33 179-RI 11 IF Figure 1 Calculated BSP Region Boundary Decay Ratios for HCGS Cycle 14 1o of 11
NEDO-33 179-RI Core Flow (Mlb/hr) 50.00 60.00 70.00 80.00 90.00 100.00 110.00 120.00 0.00 10.00 20.00 30.00 40.00 I-1 0
Oh 19E2 iI-19 Oh C
WAJ 110 100 90 80 70 60 50 40 30 20 to 0
A:
Natural Circulation B:
Minimum Pump Speed C:
57.61 Power/
39.2% Flow D: 100.Ot Power/
94.8% Flow DI: 87.0O Power/
76.6% Flow E: 100.0% Power/ 100.0% Flow El: 87.0% Power/ 100.0O Flow F: 100.0O Power/ 205.0% Flow F': e7.0t Power/ 10S.0% Flow G:
20.6% Power/ 105.0% Flow tt.
-in I ow.r/ lO.t%
i n
ls i
MELLLA Boundary Line D
E F
t6.95% FtPU Rod Une (101.4% OLTP Rod line)
A2-lCA/
A2-3840 MWt 3339 MMt 3293 MNVt I:
20.6% Power/
41.31 Flow J:
52.9% Power/
33.7t Flow BSP Scram Reglon I AjI.CA Al Boundary Line (proposed)
Bi-ICA B2 B2-lCA A
13 t5.76%. Eltt Rod Une (1004 OLTP Rod Une) 4500
-4000 3500 3000 3 I-2500 e 0
2000 c:
1000 500 0
Increased Core Flow Region BSP Controlled Entry Region II.....
Boundary Line (proposed)
Cavittion Interlock u-u.
100) LPv 100t OLTP 0
lOOt Core Flow 11 G
3840 MWt 3293 M4Wt 100.0 Mlb/hr I
1~~~ ~
0 10 20 30 40 50 60 70 80 90 Rated Core Flow (%)
Figure 2 Proposed BSP Regions for Cycle 14 100 I10 120 11 of 11