ML20217R359
| ML20217R359 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 10/15/1996 |
| From: | Marion A NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| To: | Sheron B NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20217R053 | List: |
| References | |
| PROJECT-689 GL-95-05, GL-95-5, NUDOCS 9709050095 | |
| Download: ML20217R359 (13) | |
Text
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N 'J ( l l A R (NIRGY INSilTUlf Alexander Marion
$$o Y October 15,1996 Dr. Brian W. Sheron
. Acting Associate Director
~ Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 PROJECT NUMBER: 689
SUBJECT:
Response to NRC Letter Dated February 9,1996, Regarding New Probe Variability Criteria In our letter dated January 23,1996, industry proposed a methodology for implementing the 10% new probe variability criteria as stated in Generic Letter (GL) 95 05. The NRC responded in a letter dated February 9,1996, requesting resolution of two related issues. This letter is in response to your February 9,1996, letter.
To briefly summarize the issues, the NRC accepted industry's new probe variability methodology which requires in part, that the primary frequency voltage response of a new probe be compared to the nominal response determined by the vendor to ensure that the new probe is within plus or minus 10% of the nominal response.
- The NRC requested a one time performance demonstration to verify the primary frequency voltage response.
The second issue is NRC's request that nominal voltage res.gonses for all bobbin probe types to be used in the application of Generic Letter 95 05 be submitted for future reference and inspection activities.
With regard to the first issue, industry has reviewed data used originally to support the position that only the primary frequency was required for tests on new probes to verify that they met the voltage variability specification of plus or minus 10%.
Based on this review, industry can not justify that testing at only the primary frequency is sufficient. Data were identified where the mix frequency results had higher variability than those from tests performed with the primary frequency.
9709050095 970829 DR ADOCK 05000202 pm
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Dr. Brian W. Sheron October 15,1996 Page 2 Based on these results industry recommends that new probes be tested at both the primary and mix frequencies. The implementation of this requirement is simple and cost effective.
With regards to the second issue, it is noted that Generic Letter 95 05, paragraph 3.c.2 states,"Once the probe has been calibrated on the 20 percent through wall holes, the voltage response of new bobbin coil probes for the 40 percent to 100-percent American Society of Mechanical Engineers (ASME) through wall holes should not differ from the nominal by more than plus or minus 10 percent."
Zetec and Westinghouse are the manufacturers of the probes allowed for use in applying Generic Letter 95 05. A brief description of the procedures used by each vendor and their respective test results are included in Enclosure 1.
The two vendors developed nominal voltages for each of the 40 percent to 100 percent holes in their calibration standards. This is done for both the primary and mix frequency signal outputs for the probe designs provided for Generic Letter 95 05 application. These nominal voltages, reported here, in Enclosure 1 as references for comparison with future probes to be tested for certification that the 10% voltage associated with the mix frequency is different between Westinghouse and Zetec, as explained in the description of Zetec's procedure. The difference does not invalidate either vendors' ability to provide probe manufacturing consistency for their individual probe design.
If you any questions regarding this information, please call me at (202) 739-8080 or Clive Callaway at (202) 739 8114.
Sincerely,
{$0khda'x Alex Marion
- AM/RCC/ead Enclosure c:
Ted Sullivan, NRC David Steininger, EPRI David Goetcheus. TVA Sherry Bernhoft, WPS
Bobbin Probe Variability Westinghouse Procedure Variation of Voltage Responses to ASME Drilled Hole Flaws 720 mil Bobbin Probes The responses of 0.72" diameter Echoram "Long Life" bobbin probes used for amplitude measurements of ODSCC on 7/8" tubing at drilled tube support plate (TSP) intersections must lie within 10% for each of the ASME drilled hole flaws on a reference standard. The standard used in the field must be normalized to the laboratory standards used in the development of the Alternate Repair Criteria's database. The reference voltages against which each probe is compared were developed by recording the responses to the same standard of at least 10 individual production run bobbin probes. Although not required, the standard (AS-019 91) was " transferred" from the original 7/8" EPRI laboratory standard (AS-014-89) by common testing with the original Echoram BPRMS probe on which the Alternate Repair Criteria's database referenced in NRC's Generic Letter 95-05 for 7/8" tubing is based.
The variability of responses to individual production line probes was then documented by analysis of the eddy current data obtained for each probe passed through the AS-019-91 ASME standard; data collected at 400 Hz and at the output of the 400/100 Hz mix are summarized in the attached tables. It is shown that the variability of the responses from 12 production probes is well within the 10% criterion for all the ASME drilled holes when each probe is calibrated at 400 Hz with the 4x20% holes set at 4.00 volts.
All future bobbin probes planned for Alternate Repair Criteria inspections under Generic Letter 95-05 will have amplitudes with voltages within 110% of the average voltages for each flaw, when voltages are normalized to the 20% flaw values. Therefore, the acceptable voltage range, as given in the attached tables for ASME standard AS-019-91 flat bottom drilled holes, is used as an acceptance criterion for all future 0.720" diameter bobbin probes used for Alternate Repair Criteria applications under Generic Letter 95-05. Average voltages were obtained by averaging the individual probe voltages. The acceptable voltage range is 10% about the average for each flaw.
4
_ _ _... _ - _ _ _. - ~
j Echoram 720-LLMC Bobbin Probe (0.720" Long Life) 400 Khz Amplitude Responses to ASME Standard Flaws
+
it.
Standard AS-019-91
?
Probe 4x100%
80 %
- 60%
40 %
4x20%
i 1
6.07..
3.97 3.75 3.46 4.00 l
2 6.22 4.00 3.78 3.40 4.00 i
3 6.31 4.04
- 3.78 3.40 4.00 4
6.25 4.%
3.81 3.41.
4.00 5
6.29 4.07 3.83 3.44 4.00 6
6.09 3.94 3.68-3.33 4.00' 7
6.18-4.01 3.79 3.40 4.00 8
6.05 3.95 3.68 3.32 4.00 9
6.04 3.97 3.70 3.32 4.00 10 6.22 4.% -
3.77 3.35 4.00 11 6.12 4.03 3.77 3.41 4.00 12 6.41 4.18 3.90 3.49 4.00 Acceptable.
Voltage 6.81 - 5.57 4.42 - 3.62 4.15 - 3.39 3.73 - 3.05 N/A Range
Echoram 720-LLMC Bobbin Probe C.720" Long Life).
T 400/100 Khz Mix Amplitude Responses 'a ASME Standard Flaws
-i Standard AS-019-91 Probe' 4x100%
80 %
60 % -
40 %
4x20% -
- l 1 --
6.90 4.24 3.62 2.82 2.89 2
7.02 4.27-3.65 2.86 2.87 3
7.12 4.30 3.63 2.86 2.92 4
7.07 4.33 3.67 2.88 2.91 5-7.14 4.33 3.70 2.90 2.92 6
6.91 4.23-3.55 2.81 2.88 7
7.00 4.27 3.66'
-2.87 2.90
-8 6.85 4.23 3.58 2.79 2.94
.9 6.86 4.25 3.56 2.79 2.92' 10 7.04.
'4.32 3.64-2.82
~ 2.90 i
11 6.95 4.28 3.62 2.87 -
2.89-12 7.24
-.4.45 3.76-2.94 2.93 Acceptable Voltage 7.71 - 6.31
- 4.72 - 3.86 4.00 - 3.28
- 3.14 - 2.57 3.20 - 2.62 Range i
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i 610 mil Bobbin Probes i
The responses of 0.61" diameter Echoram "Long Life" bobbin probes used for amplitude j
measurements of ODSCC on 3/4" tubing at drilled tube support plate (TSP) intersections must lie within i10% for each of the ASME drilled hole flaws on a reference standard. The standard used in the field must be normalized.to the laboratory standards used in the development of the Alternate Repair Criteria's database. The reference voltages against which each probe is compared were developed by recording the responses to the same standard of at least 10 individual production run bobbin probes. Although not required, the standard (AS-0020-92) was " transferred" from the original 3/4" EPRI laboratory standard (AS-009-91) by common testing with the original Echoram BPRMS probe on which the Alternate Repair Criteria database referenced in NRC's Generic Letter 95-05 for
- 3/4" tubing is based.
The variability of responses to individual production line 0.610" probes was then documented by analysis of the eddy current data obtained for each probe passed through the AS-002-92 ASME standard; data collected at 550 Hz and at the output of the 550/130 Hz mix are summarized in the attached tables. It is shown that the variability of the responses from-16 production probes is well within the 10% criterion for all the ASME drilled holes when each probe is calibrated at 550 Hz with the 4x20% holes set at 4.00 volts.
All future bobbin probes planned for Alternate Repair Criteria inspections under Generic Letter 95-05 will have amplitudes with voltages within 10% of the average voltages for each flaw, when voltages are normalized to the 20% flaw values. Therefore, the acceptable voltage range, as given in the attached tables for ASME standard AS-002-92 flat bottom drilled holes,is used as an acceptance criterion for all future 0.610" diameter bobbin probes used for Alternate Repair Criteria applications under Generic Letter 95-05. Average voltages were obtained by averaging the individual probe voltages. The acceptable voltage-range is 10% about the average for each flaw.
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Echoram 610-LLMC Bobbin Probe (0.610" Long Life) 550 Khz Amplitude Responses to ASME Standard Flaws Standard AS-002-92 Probe 4x100%
80 %
-60 %
40 %
4x20%
1
.4.58 4.37-4.38 3.21
.4 2
4.74-
~ 4.49
-4.44 3.24 4
3-4.33 4.14 4.15 3.05 -
4-4 4.50 4.33 -
4.36 3.21 4
5 4.82-4.56-4.56 3.28 4
4 6
14.59 4.40 4.39 3.20
- 4-t 7-4.70 4.45 4.41 3.22:
4 8
4.33 4.18-4.27 3.12 4
9
-4.34 4.17 -
4.18 3.06 4
10 4.92 4.61 4.62 3.29 4
-11 4.63 4.38 4.40 3.15
=4-12 4.60 4.36 4.38-3.18 4
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4.46 4.28 4.31 3.14 4
14-4.45 4.26 4.25 3.13 4-15 4.49 4.29 J 4.33-3.15 4
16 4.53 4.31 4.31 3.15 4
Acceptable Voltage 5.02 _4.10 4.79 - 3.92 4.80 - 3.92
- 3.49-2.85 N/A Range s
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Echoram 610-LLMC Bobbin Probe (0.610" Long Life)
= 550/130 Khz Mix Amplitude Responses to ASME Standard Flaws Standard AS-002-92 q
Probe 4x100%
80 %
60% -
40 %
-4x20%
3 1
5.54 4.85 4.24 2.50 2.63
-2 5.66 4.99 4.33 2.55 2.69 3
5.26 4.61 4.03 2.37 2.69 l-4 5.47 4.84 4.26 2.54 2.72 5
5.82 5.08
.4.46 2.56 2.67 l-6 5.55 4.91-4.30 2.51 2.71-7 5.65 4.96 4.28 2.51 2.67 8
5.20 4.61 4.10 2.43
-2.66
~
9 5.30 4.63 4.04 2.40 2.70
~
10 5.92 5.12 4.49-
.2.57 2.68 11 5.6
~ 4.88 4.29 2.46 2.7) 12 5.55 4.83 4.25 2.49 2.67 13 5.40 4.77 4.17 2.45 2.E 14 5.43 4.75 4.13 2.43 -
2.67 15 5.44 4.77 4.20 2.45
?.64 16 5.48 4.81-4.20 2.48 2.69 Acceptable Voltage-6.06 - 4.96 5,31 - 4.35 4.66 - 3.82 2.73 - 2.23 2.95 - 2.41 Range
1 Zetec Procedure The Zetec probes used in establishing the average voltages and acceptable voltage ranges are Zetec A-720-MULC (0.720") and Zetec A-610-MULC (0.610") bobbin coil probes.
The Zetec procedure is similar to the Westinghouse procedure and accomplishes the same objective of establishing reference (nominal) voltages and criterion to judge the acceptability of newly manufactured probes by Zetec for use under NRC's Generic Letter 95-05. Minor differences between Zetec's and Westinghouse's procedures do exist. Specifically, Zetec's procedure established the average voltage values from 10 probes, each passed 5 times through the standard. This was done for four individual standards for each of two tube sizes. Standards Z-13059, Z-13060, Z-13061, and Z-13062 were used for the 7/8 inch x 0.050 inch tubing. Standards Z-13063, 2-13064, Z-13065, and Z-13074 were used for the 3/4 inch x 0.043 inch tubing. A total of 400 inspections were parformed. Additionally, the Zetec procedure sets the probe's voltage response on the 4 x 20% flaw to 4.0 volts for the primary frequencies and to 2.75 volts for the mix frequencies. The Westinghouse procedure sets the probe's voltage response on the 4 x 20% flaw to 4.0 volts and does not reset the voltage response to 2.75 volts for the mix frequencies. Finally, the standards used by Zetec were not "transfered" from the original EPRI laboratory standards by common testing with the original probes on which the Alternate Repair Critaria's database referenced in NRC's Generic Letter 95-05 is based.
The above noted differences between vendor procedures are acceptable. The procedure's objec,tive is to establish new probe " response consistency" during manufacturing with the manufacturer's probe design used originally to establish the Alternate Repair Criteria's database referenced in NRC's Generic Letter 95-05. The difference between probes manufactured by different vendors have been taken into account in the Alternate Repair Criteria methodology because both probe designs were used to establish the database. That is, the difference between ASME hole i
voltage response between probes used in these tests is similar to that found in the original Alternate Repair Criteria development tests as documented in EPRI report "Outside Diameter Stress Corrosion Cracking (ODSCC) of Steam Generator Tubing at Tube Support Plates-A Database for Alternate Repair Limits," NP-7480-L, Volumes 1 and 2, August 1992. It was further found during these development tests, as documented in this report, that the voltage response difference Letween probes on ASME standa.rds has a negligible effect on actual crack response. This report also shows that small differences in crack voltage response resulting from 100% throughwall versus 20% throughwall hole normalization were acceptable.
Finally, it is noted that standards used in the field must be normalized to the laboratory standards used in the development of the database through the use of a
" transfer" standard. Therefore, it is not necessary to have the vendor standards, used to validate probe manufacturing consistency, " transferred" from the original EPRI labor. *ory standard.
Variation of Voltage Responses to ASME Drilled Hole Flaws Zetec Reference Signal Voltages 0.875" OD x 0.050" Wall (400 Khz)
Flaws Standards Z-13059 Z-13060 Z-13061 Z-13062 100 % -
7.98 8.89 8.93 7.94 4 x 100%
7.07 7.19 7.20 6.44 80 %
4.45 4.92 4.91 3.91 60 %
5.02 4.38 4.42 3.61 l
40%
3.26 3.61 3.64 3.53 4
4 x 20%
4.00 4.00 4.00 4.00 l
Zetec Acceptable Voltage Ranges 0.875" OD x 0.050" Wall (400 Khz)
Flaws Standards Z-13059 Z-13060 Z-13061 Z-13062 100 %
8.78 - 7.18 9.78 - 8.00 9.82 - 8.04 8.73 - 7.14
-4 x 100%
7.78 - 6.36 7.91 - 6.47 7.92-6.48 7.08 - 5.79 80 %
4.89 - 4.00 5.41 - 4.43 5.40 - 4.42 4.30 - 3.52 60 %
5.53 - 4.52 4.82 - 3.94 4.86 - 3.98 3.97-3.25 40%
3.58-2.93 3.97 - 3.25 4.00 - 3.27 3.88 - 3.18 4 x 20%
N/A N/A N/A N/A
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. Zetec Reference Signal Voltages y
0.875" OD x 0.050" Wall (400/100 Mix)
-=
- Flaws._
Standards
-Z-13059 Z-13060-
' Z-13061 Z-13062
.100 %
7.87 9.14 9.20 8.51 4 x 100%
7.09 7.54 7.58 7.04-80% ~
4.24-
-4.92 4.92 4.02 60 %
4.34 4.02 4.07 3.40
' 40% -
2.54 2.97-
- 3.00 -
2.90 4 x 20% -
2.75 2.75 2.75 2.75 7
Zetec Acceptable Voltage Ranges j
0.875" OD x 0.050" Wall (400/100 Mix)
Flaws Standards j-Z-13059 Z-13060 -
Z-13061-
- Z-13062
'100 %
8.66 - 7.08 10.05 - 8.22 10.12 - 8.28-9.36-7.66-i-
4 x 100%
7.80 - 6.38 8.29 - 6.73 8.34 - 6.82-7.74 - 6.34 j-80% -
- 4.66 - 3.81
. 5.41 - 4.43 ~
5.41-- 4.43-4.42-3.62 60 %
4.77 - 3.90 4.42 - 3.62 4.48 - 3.66 3.74 - 3.06 -
40 %
2.80 - 2.29 3.27 - 2.68 3.30 - 2.70 3.18 - 2.61 4 x 20%.
N/A N/A.
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Zetec Reference Signal Voltages 0.750" OD x 0.043" Wall (550 Khz)
Flaws Standards Z-13063 Z-13064 Z-13065 Z-13074
(
100 %
.4.33 5.01 4.89 4.44 4 x 100%
3.93 4.17 4.18 3.68 80 %
4.76 5.47 5.30 4.09 60 %
4.58 5.87 6.02 4.23 40%
4.02 4.63 4.19 3.48 j
4 x 20%
4.00 4.00 4.00 4.00 i
Zetec Acceptable Voltage Ranges 0.750" OD x 0.043" Wall (550 Khz) t Flaws Standards Z-13063 Z-13064 Z-13065 Z-13074 100 %
4.76 - 3.89 5.51 - 4.51 5.38-4.40 4.88 - 4.00 4 x 100%
4.33 - 3.54 4.59 - 3.75 4.60 - 3.76 4.05 - 3.31 80 %
5.24 - 4.28
-6.02 - 4.93 5.83 - 4.77 4.50 - 3.68 60 %
5.04 - 4.13 6.46 - 5.29 6.63 - 5.42 4.65 - 3.80 40 %
4.42 - 3.62 5.09 - 4.16 4.60 - 3.77 3.82 - 3.13 4 x 20%
N/A N/A N/A N/A
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-Zetec Reference Signal Voltages a
0.750" OD x 0.043" Wall (550/130 Mlx) -
Flaws-Standards Z-13063 Z-13064 Z-13065 Z-13074
-100 %
4.63 5.44 5.40 4.83-
- 4 x 100% -
4.32 4.64 4.72
-4.07 i
80% -
4.67 5.42 5.37 4.14 60 %
4.27-5.41 5.41 3.89 40 %
3.38 3.75 3.41 2.77
' 4 x 20%
2.75 2.75 2.75 2.75 Zetec Acceptable Voltage Ranges 0.750" OD x 0.043" Wall (550/130 Mix)
Flaws
- Standards 3
Z-13063 Z-13064
- Z-13065 Z-13074 100 %
- 5.10-4.17 5.99 - 4.90 5.94 - 4.86 5.31 4.35-4 x 100%.
4.75 - 3.88 5.11 - 4.18 5.19 - 4.25 "
4.48 - 3.67 80% -
5.14 - 4.20
.5.97 - 4.88-5.90 - 4.83.
4.58 - 3.73 60% -
4.70 - 3.85
. 5.95 - 4.87.
5.95 - 4.87 4.28-3.50-
- 40% L 3.72 - 3.04 4.12-3.37-3.75 - 3.07 3.04 - 2.49 5
4 x 20%
N/A N/A N/A N/A-1 1
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