ML14269A323
| ML14269A323 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 09/05/2014 |
| From: | Westinghouse |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML14269A321 | List:
|
| References | |
| L-MT-14-075, TAC MF3330 LTR-BWR-ENG-14-034-NP | |
| Download: ML14269A323 (52) | |
Text
L-MT-14-075 ENCLOSURE 5 WESTINGHOUSE LETTER REPORT, LTR-BWR-ENG-14-034-NP NON-PROPRIETARY INVESTIGATION INTO THE CAUSE OF EXCEEDING THE LEVEL 1 (L1) AND LEVEL 2 (L2) LIMIT CURVES GENERATED BASED ON 2011 MONTICELLO MAIN STEAM LINE STRAIN GAUGE DATA 51 pages follow
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP Investigation into the Cause of Exceeding the Level 1 (LI) and Level 2 (L2) Limit Curves Generated Based on 2011 Monticello Main Steam Line Strain Gauge Data September 5, 2014 Westinghouse Electric Company LLC 1000 Westinghouse Drive Cranberry Township, PA 16066 USA
© 2014 Westinghouse Electric Company LLC All Rights Reserved
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP, Revision 1 1
=
Background===
In early 2014, during power ascension activities (at 1864 MWt) for the extended power uprate (EPU) license amendment, the United States Nuclear Regulatory Commission (U.S. NRC) questioned the accuracy of certain steam dryer data that had been provided as information by Monticello Nuclear Generating Plant (MNGP). After investigation, Northern States Power Minnesota (NSPM) discovered that data errors existed in the replacement steam dryer (RSD) analyses. The errors consisted of 1) a strain gauge (SG) adjustment factor in the data acquisition system (DAS) that was set to a value that reduced the amplitude of the data acquired by a constant factor and; 2) an inadvertent reversal of main steam line (MSL) strain gauge signals, on MSL C, [
]a,c In Reference 1, the NRC requested additional information (RAIs) related to this issue. NSPM/Westinghouse Electric Company reanalyzed the steam dryer performance using corrected information without changing the benchmark methodology and provided this analysis in response to the RAI request (Reference 2). The minimum alternating stress ratio (MASR) for operation at 2004 MWt that was used to derive the benchmark limit curves in References 2 and 3 [
]a,c These limit curves were generated based on the 2011 MSL pressure power spectral densities (PSDs) to be consistent for comparison with past work.
Following this submittal, the NRC informally requested that pressure PSDs calculated based on 2014 data, recorded at 1775 MWt, be plotted against the new limit curves provided as part of Reference 2. On August 6, 2014, Xcel Energy recorded a MSL strain gauge dataset at the 1775 MWt thermal power level. Westinghouse has evaluated this dataset and plotted the MSL pressure PSDs against the limit curves derived based on corrected 2011 SG data. [
]a,c Operability analyses existed and were enhanced to verify that the steam dryer was operable at 1775 MWt and at previous operation that included short periods at power levels up to 1864 MWt.
[ ]a,c A new set of limit curves, developed based on August 6, 2011 data, is also provided. A separate document will be provided to the NRC that describes the alternate power ascension process that NSPM/Westinghouse Electric Company will use to perform the remainder of EPU power ascension testing.
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP References
- 1. Email from T Beltz (NRC) to J Fields (NSPM), "Monticello Nuclear Generating Plant -
Draft Request for Additional Information (EMCB) in Support of EPU Power Ascension (TAC No. MF3330)," dated May 15, 2014. (Attached in EDMS)
- 2. Letter from K Fili (NSPM), "Monticello Extended Power Uprate: Replacement Steam Dryer - Response to NRC Requests for Additional Information, Revised Limit Curves and Supporting Information (TAC No. MF3330)," July 22, 2014. (Attached in EDMS)
- 3. Westinghouse Letter LTR-BWR-ENG-14-010, Revision 1, "Responses to the US NRC Request for Additional Information Relative to the Monticello Replacement Steam Dryer Acoustic/Structural Analyses Set #7," July 18, 2014.
- 4. Xcel Energy Design Information Transmittal (DIT) 1353, "EPU Data Acquisition System (DAS) Main Steam Line (MSL) Data," August 6, 2014.
- 5. Xcel Energy Design Information Transmittal (DIT) EC-13638, "Transmittal of SIA Letter AMK-1 1-001, Revision 1 confirming that the pressure conversion factors remain unchanged and strain gage data taken during power ascension following the spring 2011 refuel outage," June 2011.
- 6. Structural Integrity Associates Report 1301246.406.R2, "Investigation of Signal Discrepancies in Extended Power Uprate Strain Gage Data," April 10, 2014.
- 7. Structural Integrity Associates Report 1301246.407.RO, "Review of Strain Gage Signal Performance over Extended Time Periods," August 14, 2014.
- 8. Westinghouse Letter LTR-BSA-14-9, Revision 0, "Monticello Power Ascension Assessment of 105% of CLTP Power Level Data," May 17, 2014.
- 9. Westinghouse Letter LTR-BWR-ENG-14-031, Revision 0, "Monticello Steam Dryer Structural Integrity," August 14, 2014.
- 10. Structural Integrity Associates Report 1301246.408.RO, "Summary of Onsite DAS Functionality Verification," August 26, 2014.
2
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP Evaluation Westinghouse has evaluated the 1775 MWt dataset, transmitted from Xcel Energy to Westinghouse on August 6, 2014 in Reference 4.
a,c
]a,c The LI and L2 curves in Figures 1A through 8C are based on the MASR consistent with the 2011 MSL SG data projected to 2004 MWt in Reference 3.
[
Table 2 Recirculation Pump Speeds for 2011 and 2014
]a,c a,b,c 3
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP Ii Ia,c 3.SvrlcanlIaecage lgtyfo 01t 04 Ia,c
- 3. Several channels have changed slightly from 2011 to 2014. [
]a,c The changes include:
0 [
Ia,c 0
[
]a,c I
Ia,c From the SIA study, [
Ia,c 4
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP II
]a,c a
I Ia,c I
Ia,c I
I a,c The changes to the MASR for MSL SG datasets taken at different times are summarized in Table 2.
Table 2 I
I a,c a,b,c 5
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP Conclusion Ia,c 6
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 1-A MSL A Upstream 0-250 Hz 7
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 1-B MSL A Upstream 0-100 Hz 8
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 1-C MSL A Upstream 100-250 Hz 9
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-1 4-034-NP a,b,c Figure 2-A MSL A Downstream 0-250 Hz 10
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP a,b,c Figure 2-B MSL A Downstream 0-100 Hz 11
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 2-C MSL A Downstream 100-250 Hz 12
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-1 4-034-NP a,b,c Figure 3-A MSL B Upstream 0-250 Hz 13
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 3-B MSL B Upstream 0-100 Hz 14
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 3-C MSL B Upstream 100-250 Hz 15
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP a,b,c Figure 4-A MSL B Downstream 0-250 Hz 16
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 4-B MSL B Downstream 0-100 Hz 17
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 4-C MSL B Downstream 100-250 Hz 18
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 5-A MSL C Upstream 0-250 Hz 19
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP a,b,c Figure 5-B MSL C Upstream 0-100 Hz 20
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-1 4-034-NP a,b,c Figure 5-C MSL C Upstream 100-250 Hz 21
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-1 4-034-NP 7 a,b,c Figure 6-A MSL C Downstream 0-250 Hz 22
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-1 4-034-NP a,b,c Figure 6-B MSL C Downstream 0-100 Hz 23
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 6-C MSL C Downstream 100-250 Hz 24
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 7-A MSL D Upstream 0-250 Hz 25
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 7-B MSL D Upstream 0-100 Hz 26
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 7-C MSL D Upstream 100-250 Hz 27
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 8-A MSL D Downstream 0-250 Hz 28
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 8-B MSL D Downstream 0-100 Hz 29
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 8-C MSL D Downstream 100-250 Hz 30
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 9 [
Ia,c 31
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 10 [
Ia,c 32
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP a,b,c Figure 11 [
Ia,c 33
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP a,b,c Figure 12 [
Ia,c 34
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP I a,b,c Figure 13 [
Ia,c 35
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP 7a,b,c Figure 14 [
Iaxc 36
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP 2 a,b,c Figure 15 [
I aC 37
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 16 [
I a,c 38
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP Figure 17 Sample Plant 2, MSL A Upper a,b,c 39
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP a,b,c Figure 18 Sample Plant 2, MSL A Lower 40
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 19 Sample Plant 2, MSL D Upper 41
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 20 Sample Plant 2, D Lower 42
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 21 MSL A Upstream 43
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-I 4-034-NP a,b,c Figure 22 MSL A Downstream 44
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 23 MSL B Upstream 45
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 24 MSL B Downstream 46
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 25 MSL C Upstream 47
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 26 MSL C Downstream 48
Westinghouse Non-Proprietary Class 3 LTR-BWR-ENG-14-034-NP a,b,c Figure 27 MSL D Upstream 49
Westinghouse Non-Proprietary Class 3 LTR-B WR-ENG-I 4-034-NP a,b,c Figure 28 MSL D Downstream 50