ML063180243

Gnf Additional Information Regarding the Requested Changes to Technical Specification SLMCPR, Cycle 7

ML063180243
Person / Time
Site:	Browns Ferry
Issue date:	11/02/2006
From:	Global Nuclear Fuel - Americas
To:	Office of Nuclear Reactor Regulation
References
eDRFSection 0000-0044-1500, Rev 1, TVA-BFN-TS-455
Download: ML063180243 (23)

Text

GNF Attachment 11/2/2006 eDRFSection: 0000-0044-1500, Rev. 1 GNF Additional Information Regarding the Requested Changes to the Technical Specification SLMCPR Browns Ferry Unit 1 Cycle 7 Page 1 of 23

GNF Attachment Proprietary Information Notice This document is the GNF non-proprietary version of the GNF proprietary report. From the GNF proprietary version, the information denoted as GNF proprietary (enclosed in double brackets) was deleted to generate this version.

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GNF Attachment Table of Contents 1.0 M ETHO DO LO G Y .......................................................................................................................................... 4 2.0 DISCUSSION ................................................................................................................................................... 4 2.1. M AJOR CONTRIBUTORS To SLMCPR CHANGE .......................................................................................... 4 2.2. DEVIATIONS IN NRC-APPROVED UNCERTAINTIES ..................................................................................... 5 2 .2 .1. R -F actor ................................................................................................................................................. 5 2.2.2- Core Flow Rate and Random Effective TIP Reading........................................................................ 5 2.3. DEPARTURE FROM NR C-APPROVED M ETHODOLOGY ............................................................................... 6 2.4. FUEL AXIAL POW ER SHAPE PENALTY ...................................................................... ...............................

7 2.5. M ETHODOLOGY RESTRICTIONS ...................................................................................................................... 7 2.6. M INIMUM CORE FLOW CONDITION ................................................................................................................ 7 2.7. LIMITING CONTROL ROD PATTERNS .............................................................................................................. 8 2.8. CORE M ONITORING SYSTEM .......................................................................................................................... 8 2.9. POW ER/FLOW M AP ............ ............................................................................................................................ 8 2.10. CORE LOADING DIAGRAM .......................................................................................................................... 8 2.1 1. FIGURE REFERENCES .................................................................................................................................. 8 2.12. ADDITIONAL SLM CPR LICENSING CONDITIONS ................................................................................... 8 2.13,

SUMMARY

.................................................................................................................................................. 9

3.0 REFERENCES

............................................................................................................................................. 10 List of Figures FIGURE 1. CURRENT CYCLE CORE LOADING DIAGRAM .............................................................................................. 11 FIGURE 2. FIGURE 4.1 FROM NEDC-3260 I-P-A ......................................................................................................... 12 FIGURE 3. FIGURE 111.5-1 FROM NEDC-3260 IP-A ..................................................................................................... 13 FIGURE 4. FIGURE 111.5-2 FROM NEDC-32601P-A ..................................................................................................... 14 List of Tables TABLE I. DESCRIPTION OF CORE ................................................................................................................................. 15 TABLE 2. SLM CPR CALCULATION M ETHODOLOGIES ........................................................................................... 16 TABLE 3. M ONTE CARLO CALCULATED SLMCPR vs. ESTIMATE ......................................................................... 17 TABLE 4. NON-POW ER D ISTRIBUTION UNCERTAINTIES ......................................................................................... 19 TABLE 5. POW ER DISTRIBUTION UNCERTAINTIES ....................................................................................................... 21 TABLE 6. CRITICAL POW ER UNCERTAINTIES ............................................................................................................... 23 Page 3 of 23

GNF Attachment 1.0 Methodology GNF performed the Browns Ferry Unit 1 Cycle 7 Safety Limit Minimum Critical Power Ratio (SLMCPR) calculation in accordance to NEDE-2401 1-P-A "General Electric Standard Application for Reactor Fuel" (Revision 15) using the following NRC-approved methodologies and uncertainties:

" NEDC-32601P-A "Methodology and Uncertainties for Safety Limit MCPR Evaluations" (August 1999).

" NEDC-32694P-A "Power Distribution Uncertainties for Safety Limit MCPR Evaluations" (August 1999).

• NEDC-32505P-A "R-Factor Calculation Method for GEl 1, GEl2 and GE13 Fuel" (Revision 1, July 1999).

• NEDO-10958-A "General Electric BWR Thermal Analysis Basis (GETAB): Data, Correlation and Design Application" (January 1977).

2.0 Discussion Browns Ferry I Cycle 7 is the first cycle after a long shut down period and, therefore, no comparisons with previous cycle results are relevant and no previous cycle data is provided in this document. However, the Browns Ferry Cycle 7 SLMCPR results are well in line with other similar reactor/cycles results.

2.1. Major Contributors to SLMCPR Change In general, the calculated safety limit is dominated by two key parameters: (1) flatness of the core bundle-by-bundle MCPR distribution, and (2) flatness of the bundle pin-by-pin power/R-factor distribution. Greater flatness in either parameter yields more rods susceptible to boiling transition and thus a higher calculated SLMCPR. MIP (MCPR Importance Parameter) measures the core bundle-by-bundle MCPR distribution and RIP (R-factor Importance Parameter) measures the bundle pin-by-pin power/R-factor distribution. The impact of the fuel loading pattern on the calculated Two Loop Operation (TLO) SLMCPR using rated core power and rated core flow conditions has been correlated to the parameter MIPRIP, which combines the MIP and RIP values.

Table 3 presents the MIP and RIP parameters for the current cycle along with the TLO SLMCPR estimate using the MIPRIP correlation. If the minimum core flow case is applicable, the TLO SLMCPR estimate is also provided for that case although the MIPRIP correlation is only applicable to the rated core flow case. This is done only to provide some reasonable assessment basis of the minimum core flow case trend. Table 3 in addition presents estimated impacts on the TLO SLMCPR due to methodology deviations, penalities, and/or uncertainties deviations Page 4 of 23

GNF Attachment from approved values. Based on the MIPRIP correlation and any impacts due to deviations from approved values, a final estimated TLO SLMCPR is determined. Table 3 also provides the actual calculated Monte Carlo SLMCPRs. Given the bias and uncertainty in the MIPRIP correlation (( ý3 )] and the inherent variation in the Monte Carlo results (( {31)), the change in the Browns Ferry Unit I Cycle 7 calculated Monte Carlo TLO SLMCPR using rated core power and rated core flow conditions is consistent with the corresponding estimated TLO SLMCPR value.

2.2. Deviations in NRC-Approved Uncertainties Tables 4 and 5 provide a list of NRC-approved uncertainties along with values actually used. A discussion of deviations from these NRC-approved values follows; all of which are conservative relative to NRC-approved values. Also, estimated impact on the SLMCPR is provided in Table 3 for each deviation.

2.2.1. R-Factor At this time, GNF has generically increased the GEXL R-Factor uncertainty from ((

{3))) to account for an increase in channel bow due to the emerging unforeseen phenomena called control blade shadow corrosion-induced channel bow, which is not accounted for in the channel bow uncertainty component of the approved R-Factor uncertainty. The step "a RPEAK" in Figure 4.1 from NEDC-32601P-A, which has been provided for convenience in Figure 2 of this attachment, is affected by this deviation. Reference 4 technically justifies that a GEXL R-Factor uncertainty of (( 13))) accounts for a channel bow uncertainty of up to ((

Currently, Browns Ferry Unit 1 has not experienced any control blade shadow corrosion-induced channel bow and is not expected to experience any in Cycle 7 to the extent that would invalidate the approved R-Factor uncertainty. ((

2.2.2. Core Flow Rate and Random Effective TIP Reading At this time, GNF has not been able to show that the NRC-approved process to calculate the SLMCPR only at the rated core power and rated core flow condition is adequately bounding relative to the SLMCPR calculated at rated core power and minimum core flow; see Reference 5.

The minimum core flow condition can be more limiting due to the control rod pattern used.

GNF has modified the NRC-approved process for determining the SLMCPR to include an analysis at the rated core power and minimum licensed core flow point in addition to the analysis at the rated core power and rated core flow point. GNF believes this modification is conservative and may in the future provide justification that the original NRC-approved process is adequately bounding.

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GNF Attachment For the TLO calculations performed at 81% core flow, the approved uncertainty values for the core flow rate (2.5%) and the random effective TIP reading (1.2%) are conservatively adjusted by dividing them by 81/100. The steps "a CORE FLOW" and "a TIP (INSTRUMENT)" in Figure 4.1 from NEDC-32601P-A, which has been provided for convenience in Figure 2 of this attachment, are affected by this deviation, respectively.

Historically, these values have been construed to be somewhat dependent on the core flow conditions as demonstrated by the fact that higher values have always been used when performing Single Loop Operation (SLO) calculations. It is for this reason that GNF determined that it is appropriate to consider an increase in these two uncertainties when the core flow is reduced. The amount of increase is determined in a conservative way. For both parameters it is assumed that the absolute uncertainty remains the same as the flow is decreased so that the percentage uncertainty increases inversely proportional to the change in core flow. This is conservative relative to the core flow uncertainty since the variability in the absolute flow is expected to decrease somewhat as the flow decreases. For the random effective TIP uncertainty, there is no reason to believe that the percentage uncertainty should increase as the core flow decreases for TLO. Nevertheless, this uncertainty is also increased as is done in the more extreme case for SLO primarily to preserve the historical precedent established by the SLO evaluation. Note that the TLO condition is different than the SLO condition because for TLO there is no expected tilting of the core radial power shape.

The treatment of the core flow and random effective TIP reading uncertainties is based on the assumption that the signal to noise ratio deteriorates as core flow is reduced. GNF believes this is conservative and may in the future provide justification that the original uncertainties (non-flow dependent) are adequately bounding.

The core flow and random TIP reading uncertainties used in the SLO minimum core flow SLMCPR analysis remain the same as in the rated core flow SLO SLMCPR analysis because these uncertainties (which are substantially larger than used in the TLO analysis) already account for the effects of operating at reduced core flow.

2.3. Departure from NRC-Approved Methodology No departures from NRC-approved methodologies were used in the Browns Ferry Unit 1 Cycle 7 SLMCPR calculations.

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GNF Attachment 2.4. Fuel Axial Power Shape Penalty At this time, GNF has determined that higher uncertainties and non-conservative biases in the GEXL correlations for the various types of axial power shapes (i.e., inlet, cosine, outlet and double hump) could potentially exist relative to the NRC-approved methodology values; see References 3, 6, and 7. The following table identifies, by marking with an "X", this potential for each GNF product line currently being offered:

It (3)))

Axial bundle power shapes corresponding to the limiting SLMCPR control blade patterns are determined using the PANACEA 3D core simulator. If the bundles that could participate in setting the SLMCPR (i.e., the limiting bundles) exhibit an axial power shape identified by this table, GNF penalizes the GEXL critical power uncertainties to conservatively account for the impact of the axial power shape. Table 6 provides a list of the GEXL critical power uncertainties determined in accordance to the NRC-approved methodology contained in NEDE-2401 1-P-A along with values actually used.

For the limiting bundles, the fuel axial power shapes in the SLMCPR analysis were examined to determine the presence of axial power shapes identified in the above table. These power shapes were not found; therefore, no power shape penalties were applied to the calculated Browns Ferry Unit I Cycle 7 SLMCPR values.

2.5. Methodology Restrictions The four restrictions identified on Page 3 of NRC's Safety Evaluation relating to the General Electric Licensing Topical Reports NEDC-32601P, NEDC-32694P, and Amendment 25 to NEDE-2401 I-P-A (March 11, 1999) are addressed in References 1, 2, and 3.

No new GNF fuel designs are being introduced in Browns Ferry Unit I Cycle 7, therefore, the NEDC-32505-P-A statement "...if new fuel is introducted, GENE must confirm that the revised R-Factor method is still valid based on new test data" is not applicable.

2.6. Minimum Core Flow Condition For Browns Ferry Unit 1 Cycle 7, the minimum core flow SLMCPR calculation performed at 81% core flow and rated core power condition was limiting as compared to the rated core flow and rated core power condition. For convenience, Figures 111.5-1 and 111.5-2 from Page 7 of 23

GNF Attachment NEDC-32601P-A have been provided in Figures 3 and 4 in order to show this minimum core flow conditon relative relationship to the data on these figures. For this condition the MIP (31)); therefore, this demonstrates that the MIP criterion for determining what constitutes a reasonably bounding limiting rod pattern is still valid for this minimum core flow condition.

2.7. Limiting Control Rod Patterns The limiting control rod patterns used to calculate the SLMCPR reasonably assures that at least 99.9% of the fuel rods in the core would not be expected to experience boiling transition during normal operation or anticipated operational occurrences during the operation of Browns Ferry Unit 1 Cycle 7.

2.8. Core Monitoring System For Browns Ferry Unit I Cycle 7, the 3D MONICORE system will be used as the core monitoring system.

2.9. PowerlFlow Map The utility has provided the Cycle 7 power/flow map in a separate submittal.

2.10. Core Loading Diagram Figure 1 provides the core loading diagram for Cycle 7, which is the Reference Loading Pattern as defined by NEDE-2401 I-P-A.

2.11. Figure References Figure 2 is Figure 4.1 from NEDC-32601-P-A. Figure 3 is Figure 111.5-1 from NEDC-32601P-A. Figure 4 is Figure 111.5-2 from NEDC-32601P-A.

2.12. Additional SLMCPR Licensing Conditions For Browns Ferry I Cycle 7, no additional SLMCPR licensing conditions are included in the analysis.

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GNF Attachment 2.13. Summary The calculated SLMCPR values for Browns Ferry 1 Cycle 7 at the reactor power level of 3458 MWth are 1.07 for Two Loop Operation and 1.09 for Single Loop Operation.

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GNF Attachment 3.0 References I. Letter, Glen A. Watford (GNF-A) to U.S. Nuclear Regulatory Commission Document Control Desk with attention to R. Pulsifer (NRC), "Confirmation of lOx 10 Fuel Design Applicability to Improved SLMCPR, Power Distribution and R-Factor Methodologies",

FLN-2001-016, September 24, 2001.

2. Letter, Glen A. Watford (GNF-A) to U.S. Nuclear Regulatory Commission Document Control Desk with attention to J. Donoghue (NRC), "Confirmation of the Applicability of the GEXL 14 Correlation and Associated R-Factor Methodology for Calculating SLMCPR Values in Cores Containing GEI 4 Fuel", FLN-2001-017, October 1, 2001.

3. Letter, Glen A. Watford (GNF-A) to U.S. Nuclear Regulatory Commission Document Control Desk with attention to Joseph E. Donoghue (NRC), "Final Presentation Material for GEXL Presentation-February 11, 2002", FLN-2002-004, February 12, 2002.

4. Letter, John F. Schardt (GNF-A) to U.S. Nuclear Regulatory Commission Document Control Desk with attention to Mel B. Fields (NRC), "Shadow Corrosion Effects on SLMCPR Channel Bow Uncertainty", FLN-2004-030, November 10, 2004.

5. Letter, Jason S. Post (GENE) to U.S. Nuclear Regulatory Commission Document Control Desk with attention to Chief, Information Management Branch, et al. (NRC), "Part 21 Final Report: Non-Conservative SLMCPR", MFN 04-108, September 29, 2004.

6. Letter, Glen A. Watford (GNF-A) to U.S. Nuclear Regulatory Commission Document Control Desk with attention to Alan Wang (NRC), "NRC Technology Update -

Proprietary Slides-July 31-August 1, 2002", FLN-2002-015, October 31, 2002.

7. Letter, Jens G. Munthe Andersen (GNF-A) to U.S. Nuclear Regulatory Commission Document Control Desk with attention to Alan Wang (NRC), "GEXL Correlation for IOX 10 Fuel", FLN-2003-005, May 31, 2003.

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GNF Attachment Figure 1. Current Cycle Core Loading Diagram so90 I] OS 2 Q119E 50 E ' E8 _ID-E17E1 42 l0r J ~ 1E MOnE E1 3 5IE79@ 9101 f 1712122257 292133353ET 73941435781 53555759 Number Cycle Code Bundle Name Loaded Loaded A GE13-P9DTB391-13GZ-10OT-146-T6-3964 56 BF213 B GE 14-P1ODNAB200-3GZ-10OT-150-T6-2609 36 BF213 C GE13-P9DTB156-NOG-10OT-146-T6-2887 56 7 D GE14-P1ODNABI57-NOG-10OT-150-T6-2889 224 7 E GE14-P1ODNAB377-16GZ-10OT-150-T6-2890 96 7 F GE14-P 1ODNAB402-16GZ-10OT-150-T6-2891 32 7 G GE14-P10DNAB350-16GZ-10OT-150-T6-2892 32 7 H GE14-P1ODNAB147-NOG-10OT-150-T6-2893 20 7 I GE14-P10DNAB419-16GZ-10OT-150-T6-2894 32 7 J GE14-P10DNAB368-15GZ-10OT-150-T6-2895 72 7 K GE14-P10DNAB402-19GZ-10OT-150-T6-2896 24 7 L GE13-P9DTB163-NOG-1GOT-146-T6-2888 52 7 M GE14-P1ODNAB377-17GZ-10OT-150-T6-2897 32 7 Page 11 of 23

GNF Attachment

((I (31))

Figure 2. Figure 4.1 from NEDC-32601-P-A Page 12 of 23

GNF Attachment (3)))

Figure 3. Figure 111.5-1 from NEDC-32601P-A' Note the callouts are for illustrative purpose only.

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GNF Attachment 1[

{3}))

Figure 4. Figure 111.5-2 from NEDC-32601P-A 2 Note the callouts are for illustrative purpose only.

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GNF Attachment Table 1. Description of Core Previous Cycle Previous Cycle Rated Current Cycle Current Cycle Rated Description Minimum Core Flow Core Flow Limiting Minimum Core Flow Core Flow Limiting Limiting Case Case Limiting Case Case Number of Bundles in the N/A N/A 764 764 Core Limiting Cycle Exposure N/A N/A Point (i.e. EOC PHE BOC/MOC/EOC)

Cycle Exposure at N/A N/A Limiting Point 13500 10000 (MWd/STU)

% Rated Core Flow N/A N/A 81.0 100.0 Reload Fuel Type N/A N/A GE14/GE13 GE14/GE13 Latest Reload Fraction, Batch

%8.080 N/A N/A 88.0 88.0 Latest Reload Average N/A N/A Batch Weight % 2.63 2.63 Enrichment Core Fuel Fraction: N/A N/A 78.5 78.5 GE14 21.5 21.5 GE 13 Core Average Weight % N/A N/A 2.70 2.70 Enrichment 2.70_2.70 Page 15 of 23

GNF Attachment Table 2. SLMCPR Calculation Methodologies Previous Cycle Previous Cycle Rated Current Cycle Current Cycle Rated Description Minimum Core Flow Core Flow Limiting Minimum Core Flow Core Flow Limiting Limiting Case Case Limiting Case Case Non-power Distribution N/A N/A NEDC-32601-P-A NEDC-32601-P-A Uncertainty Power Distribution N/A N/A NEDC-32694-P-A NEDC-32694-P-A Methodology Power Distribution N/A N/A NEDC-32694-P-A NEDC-32694-P-A Uncertainty Core Monitoring System N/A N/A 3D MONICORE 3D MONICORE Page 16 of 23

GNF Attachment Table 3. Monte Carlo Calculated SLMCPR vs. Estimate Previous Cycle Previous Cycle Rated Current Cycle Current Cycle Rated Description Minimum Core Flow Core Flow Limiting Minimum Core Flow Core Flow Limiting Limiting Case Case Limiting Case Case

[1 Page 17 of 23

GNF Attachment Table 3. Monte Carlo Calculated SLMCPR vs. Estimate Previous Cycle Previous Cycle Rated Current Cycle Current Cycle Rated Description Minimum Core Flow Core Flow Limiting Minimum Core Flow Core Flow Limiting Limiting Case Case Limiting Case Case t t I I The SLO SLMCPR is from the EOC at 13500 MWd/ST cycle exposure.

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GNF Attachment Table 4. Non-Power Distribution Uncertainties Nominal Previous Cycle Previous Cycle Current Cycle Current Cycle (NRC-Approved) Minimum Core Rated Core Flow Minimum Core Rated Core Flow Value +/- G (%) Flow Limiting Case Limiting Case Flow Limiting Case Limiting Case GETAB Feedwater Flow 1.76 N/A N/A N/A N/A Measurement Feedwater Temperature 0.76 N/A N/A N/A N/A Measurement Reactor Pressure 0.50 N/A N/A N/A N/A Measurement Core Inlet Temperature 0.20 N/A N/A N/A N/A Measurement Total Core Flow 6.0 SLO/2.5 TLO N/A N/A N/A N/A Measurement Channel Flow Area 3.0 N/A N/A N/A N/A Variation Friction Factor 10.0 N/A N/A N/A N/A Multiplier Channel Friction FactorMutipi 5.0 N/A N/A N/A N/A Factor Multiplier I Page 19 of 23

GNF Attachment Table 4. Non-Power Distribution Uncertainties Nominal Previous Cycle Previous Cycle Current Cycle Current Cycle (NRC-Approved) Minimum Core Rated Core Flow Minimum Core Rated Core Flow Value +/- a (%) Flow Limiting Case Limiting Case Flow Limiting Case Limiting Case NEDC-32601-P-A Feedwater Flow [ (3))] N/A N/A [1 1311 Measurement Feedwater Temperature (( {3})) N/A N/A (( 131] (( ]

Measurement Reactor Pressure ))N/A N/A((

Measurement Core Inlet Temperature 0.2 N/A N/A 0.2 0.2 Measurement Total Core Flow 6.0 SLO/2.5 TLO N/A - N/A 6.0 SLO/3.09 TLO 6.0 SLO/2.5 TLO Measurement Channel Flow Area R 3})) N/A N/A {3[)]

Variation Friction Factor 131)) N/A N/A 31))

Multiplier ((_N/AN/A_((__[__3_))

Channel Friction FactorMutipi 5.0 N/A N/A 5.0 5.0

_Factor Multiplier IIII Page 20 of 23

GNF Attachment Table 5. Power Distribution Uncertainties Previous Cycle Previous Cycle Current Cycle Current Cycle Minimum Core Rated Core Flow Minimum Core Rated Core Flow Flow Limiting Case Limiting Case Flow Limiting Case Limiting Case GETAB/NEDC-32601-P-A GEXL R-Factor (( {3})) N/A N/A N/A N/A Random Effective 2.85 SLO/1.2 TLO N/A N/A N/A N/A TIP Reading Systematic Effective 8.6 N/A N/A N/A N/A TIP Reading NEDC-32694-P-A, 3DMONICORE GEXL R-Factor (( 3"1]1 N/A N/A (( 13[)) (( t3}]

Random Effective 2.85 SLO/1.2 TLO N/A N/A 2.85 SLO/1.5 TLO 2.85 SLO/1.2 TLO TIP Reading TIP Integral (( 13}] N/A N/A (( n')) [ {3)))

Four Bundle Power Distribution Surrounding TIP [ ] N/A N/A (( {3)) (( {3)))

Location Contribution to Bundle Power N/A N/A [ 3}]

Uncertainty Due to LPRM Update Page 21 of 23

GNF Attachment Table 5. Power Distribution Uncertainties Nominal Previous Cycle Previous Cycle Current Cycle Current Cycle Description (NRC-Approved) Minimum Core Rated Core Flow Minimum Core Rated Core Flow

(%)

u Flow Limiting Case Limiting Case Flow Limiting Case Limiting Case Contribution to Bundle Power Due to (( 13)) N/A N/A (( {31)) (( 131))

Failed TIP Contribution to Bundle Power Due to (( (31)) N/A N/A (( 3})) (( 3))

Failed LPRM Total Uncertainty in Calculated Bundle (( *3I)) N/A N/A (( 3)) (( {3}))

Power Uncertainty of TIP Signal Nodal (( U31)) N/A N/A (( {3J)) (( 13111 Uncertainty I Page 22 of 23

GNF Attachment Table 6. Critical Power Uncertainties Previous Cycle Previous Cycle Current Cycle Current Cycle Description Minimum Core Rated Core Flow Minimum Core Rated Core Flow

+/- o (%) Flow Limiting Case Limiting Case Flow Limiting Case Limiting Case

[3[

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