ML030140187
| ML030140187 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 01/06/2003 |
| From: | Jordan T South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| G25, NOC-AE-02001439 | |
| Download: ML030140187 (12) | |
Text
Nuclear Operating Company South Tex7a PI/ect Ekctdc GenertAMn StatIon PO Baox289 Kadsworth, Texas 77483 p*
January 6, 2003 NOC-AE-02001439 File No.: G25 1 OCFR50.55a U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Response to Request for Additional Information Regarding Revised Request for Approval of an Alternative Approach for Containment Concrete and Tendon Surveillances (RR-ENG-37)
Reference:
Letter, T. J. Jordan to NRC Document Control Desk, "Request for Approval of an Alternative Approach for Containment Tendon Surveillances (RR-ENG-37)
In accordance with the provisions of 10CFR50.55a(a)(3)(i), the referenced letter from the South Texas Project requested approval of an alternative to ASME Section Xl, paragraph IWL 2421(b).
This specified the inservice inspection intervals to be applied in examination of containment concrete and unbonded post-tensioning systems, and IWL-2521, which describes the tendon selection process. This letter is in response to questions forwarded from the NRC requesting clarification of points presented previously. The requested information is attached.
If there are any questions, please contact either Mr. Philip Walker at 361-972-8392 or me at 361-972-7902.
Vice President, Engineering & Technical Services PLW
Attachment:
Response to Request for Additional Information Regarding Containment Tendon Surveillance Requirements
NOC-AE-002001439 Page 2 of 2 cc:
(paper copy)
(electronic copy)
Ellis W. Merschoff Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Richard A. Ratliff Bureau of Radiation Control Texas Department of Health 1100 West 49th Street Austin, TX 78756-3189 Cornelius F. O'Keefe U. S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP L. D. Blaylock/W. C. Gunst City Public Service Mohan C. Thadani U. S. Nuclear Regulatory Commission R. L. Balcom Texas Genco, LP A. Ramirez '
City of Austin C. A. Johnson AEP Texas Central Company Jon C. Wood Matthews & Branscomb C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704
Attachment NOC-AE-02001439 Page 1 of 10 SOUTH TEXAS PROJECT RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING CONTAINMENT TENDON SURVEILLANCE REQUIREMENTS NRC REQUEST:
In reviewing the information in Figure 1 and Tables 1 and 2, it is unclear what the actual measured and predicted tendon forces are. The licensee is requested to provide Tables showing actual measured pre-stressing forces for each Unit in each direction together with the forces at installation, elastic shortening losses, and slippage, if any, for the tendons selected during each prior inspections.
In the Figure, the licensee is requested to show:
(1) The trend lines (separately, for each Unit, and for U and hoop tendons) based on the inspections performed, (2) Actual measured forces as points above and below the trend lines, and (3) Predicted average tendon forces at 40 years.
The licensee is also requested to provide a summary of the method used to construct the trend lines.
SOUTH TEXAS PROJECT RESPONSE:
Supplementary Tables As requested, supplementary tables are provided for each tendon group. The columns in these tables are as follows:
(1) Tendon designation (2) Tendon end (S = "Shop end", F = "Field end")
(3) Surveillance year (1, 5, or 10)
(4) Initial liftoff force measured at installation (kips)
(5) Predicted elastic loss (kips)
(6) Predicted liftoff force at surveillance year (kips)
(7) Measured liftoff force during surveillance.
Columns 8 through 11 are explained under the section on calculation of trend lines.
Slippage is not applicable to the buttonhead-type installation at the South Texas Project.
The supplementary tables also include the average initial liftoff and predicted end-of-life liftoff for each group. These averages are calculated as the average of all tendons in the group, not just the surveillance tendons.
Figure 1 and Figure 2 As read from top to bottom, respectively, on the right side of Figure 1, the four lines are:
"* Unit 2 verticals (inverted "U"),
"* Unit 1 verticals (inverted "U"),
"* Unit 2 horizontals (hoop), and
"* Unit 1 horizontals (hoop).
Attachment NOC-AE-02001439 Page 2 of 10 Tendon loss is typically presented on a semi-log plot, with prestress loss being linear with the log of time. STP prepared Figure 1 using a standard linear scale, resulting in nonlinear trend lines. The labels on the revised Figure 1 included with this response have been enhanced for greater clarity. (There is no change to the data presented in the figure.) Figure 2 has been added to show the same trends against the log of time.
The figures show percent deviation from the predicted value on the vertical axis.
Although the request was to add the actual measured forces and end-of-life predicted average forces to the figure, the South Texas Project believes this information is more appropriately shown in the tables provided.
The South Texas Project believes that the information shown in revised Figure 1, Figure 2, and provided in the supplementary tables, while slightly different from the staff's request, meets the intent of the RAI.
Construction of Trend Lines The trend line is calculated using linear regression analysis. The trend is a straight line, represented by the equation:
Y=a + PX, where the variables Xand Yare defined as:
X= Log (T), and T = time (measured in years), and Y= Deviation from predicted prestress (measured in %).
Data points currently available are from surveillances in years 1, 5, and 10. This means the three possible values of T are 1, 5, and 10, and the corresponding values of X are Log(l), Log(5), and Log(10), which are 0, 0.69897, and 1, respectively.
All tendons were installed using similar methods, but no two were tensioned to precisely the same force.
The initial liftoff forces were recorded for all tendons immediately following installation.
Additional disparity in tendon forces was introduced due to installation sequencing (elastic losses). The subsequent time-dependent losses (creep, shrinkage, relaxation) are stress-dependent.
Since no two tendons have exactly the same stress, it follows that no two have exactly the same predicted time-dependent loss.
Therefore, predicted liftoff force is calculated individually for each tendon. In order to make meaningful comparisons among tendons and assess trends, converting them to percentage deviation from predicted values normalizes the measured liftoff forces. For example, during the first year surveillance of Unit 1, tendon V1 26-S had a predicted liftoff force of 1376 kips and an actual measured liftoff at 1402 kips. This means the actual liftoff force was 1.89% higher than expected. [(1402 - 1376)/1376 = 0.0189 = 1.89%.]
Hence, for this case, the value of Y used in the regression analysis is 1.890.
The corresponding value of X is 0.
The regression constants a and P3 are calculated according to standard statistical formulas:
a = y - f8x,
Attachment NOC-AE-02001439 Page 3 of 10 n
Ix,'-nx
_2 nn where x=--._x,,
y E=
"y, and n =number of data points in the group.
Columns 8 through 11 in the supplementary tables are defined as:
(8)
X = Log(Time),
(9)
Y = Deviation from predicted (expressed as %) where Y = 100 x [(col. 7) - (col. 6)]/(col. 6)
(10) XY = (col. 8) x (col. 9)
(11)
X2 =(col. 8) x (col. 8)
The sum of the terms in each of these columns is given at the bottom of each table.
These sums are used to calculate the constants a and P3 for each group, according to the formulas given above. Table 2 in the relief request presents the projected trends in tabular form. Using the Unit 1 horizontals as an illustration, the constant "alpha" was calculated as 2.464 and the constant "Beta" was -3.722.
Therefore, the projected deviation from predicted (expressed as %) at year 40 is:
Y=a +13X
= a + 3Log(T)
= 2.464 + (-3.722)(Log(40))
= 2.462 + (-3.722)(1.602)
= -3.50%.
This means that the Unit 1 horizontals, as a group, are trending toward 3.5% less than the predicted values at year 40. This is shown in Table 1 of the relief request. It is the least satisfactory trend of any of the four groups. To put this projection in perspective, the end-of-life containment design value for rated capacity is 56.5 psi, which is 37%
above the 41.2 psi maximum calculated pressure resulting from a LOCA.
To date, STP has performed 116 tendon liftoff tests (38 verticals and 78 horizontals).
These were distributed among the surveillances as follows:
52 at the first year, 40 at the fifth year, and 24 at the tenth year.
Each tendon has two ends, so the 116 liftoff tests convert to surveillances of 58 tendons.
Attachment NOC-AE- 02001439 Page 4 of 10 Supplementary Table S-i: Vertical Tendons (U 1)
Tendons Time Liftoff Force (Kips)
Regression Line Parameters Tendon F End Initial Elastic Loss Predicted Measured X1 X! Y, X
1 1
2 3
4 5
6 7
8 9
10 11 V126 S
1 1598 11 1376 1402 0
1.890 0
0 V126 F
1 1621 11 1391 1439 0
3.451 0
0 V144 S
1 1642 22 1401 1400 0
-0.07]
0 0
V144 F
1 1567 22 1352 1343 0
-0.666 0
0 V227 S
1 1553 22 1345 1336 0
-0.669 0
0 V227 F
1 1556 22 1346 1325 0
-1.560 0
0 V245 S
1 1591 34 1366 1363 0
-0.220 0
0 V245 F
1 1565 34 1349 1326 0
-1.705 0
0 V126 S
5 1598 11 1350 1385 0.69897 2.593 1.812141 0.48856 V126 F
5 1621:
11 1370 1406 0.69897 2.628 1.83671 0.48856 V214 S
5 1598 1
1358 1380 0.69897 1.620 1.13245 0.48856 V214 F
5 1631 1
1378 1392 0.69897 1.016 0.71013' 0.48856 V242 S
5 1603 5
1363 1381 0.69897!
1.321 0.923071 0.48856 V242 F
5 1608i 5
1367 1397 0.69897 2.195 1.534951 0.48856 V248 S
5 1603' 9
1354 1359 0.69897' 0.369 0.25811:
0.48856 V248 F
5 16081 9
1359 1382 0.69897*
1.692 1.183951 0.48856 V126 S
10 1598i 11 1348 1340 1
-0.593
-0.59347 1
V126 F
10 16211 11 1362 1380 1
1.322 1.32159ý 1
V129 S
10 15331 47 1286 1290 1
0.3))
0.31104 1
V129 F
10 1609 47 1333 1320 1
-0,975
-0.97524 1
V230 S
10 1638
-2 1379 1380 1
0.073 0.07252 1
V230 F
10 1596ý
-2 1354 1430 1
5.613 5.61300 1
15961- - Average Initial 13501-- Average Predicted (End-of-Life) 11.592 19.632 15.139 9.908 Number of liftoff tests: N = 22 See page 1 of this attachment for an explanation of columns 1 through 7, and page 3 of this attachment for an explanation of columns 8 through 11.
Attachment NOC-AE-02001439 Page 5 of 10 Supplementary Table S-2: Vertical Tendons (U2)
Tendons Time (yr)
Liftoff Force (Kips)
Regression Line Parameters Tendon End Initial Elastic Loss Predicted Measured X,
Yi XiYi I X2 1
2 3
4 5
6 7
8 9
10 11 Vl10 S
1 1605 25 1380 1421 0
2.971 0
0 V110 F
1 1605 25 1380 1377 0
-0.217 0
0 V120 S
1 1580 18 1359 1403 0
3.238 0
0 V120 F
1 1630 18 1402 1400 0
-0,143 0
0 V202 S
1 1630 15 1402 1432 0
2.140 0
0 V202 F
1 1640 15 14101 1422 0
0.851 0
0 V236 S
1 1605 4
1396 1382 0
-1.003 0
0 V236 F
1 1520' 4
1338[
1370 0
2.392 0
0 S
F S
F S
F S
F 5
5 5
5 5
5 5
5 1605 1605 1610ý 1620 15801 1630 15801 1540*
1 595E- -
25 25 13 13
-2
-2 29 29 Average Initial 1348 13481 1360ý 1361 1351 1394:
1343 1309 1412 1362 1415 1407 1479 1452 1348 1338 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 5.592 4.748 1.039 4.044 3.380 9.474 4,161 0.372 2.215 39.661 3.31855 0.72593 2.82672 2.36243 6.62237 2.90820 0.26023 1.54852 20.573 0.48856 0.48856 0,48856 0.48856 0.48856 0.48856 0.48856 0.48856 3.908 13501- - Average Predicted (End-of-Life)
Number of liftoff tests: N = 16 See page 1 of this attachment for an explanation of columns 1 through 7, and page 3 of this attachment for an explanation of columns 8 through 11.
V110 V110 V203 V203 V221 V221 V233 V233
Attachment NOC-AE-02001439 Page 6 of 10 Supplementary Table S-3: Hoop Tendons (U 1)
Tendons Time Liftoff Force (Kips)
Regression Line Parameters Tendon End (yr)
Initial Elastic Loss Predicted Measured X jI X1 Y 1
2 3
4 5
6 7
8 9
10 11 1H091 S
1 1550 5
1326 1380 0
4.072 0
0 1H091 F
1 1612 5
1367 1378 0
0.805 0
0 1H106 S
1 1579 73 1302 1345 0
3.303 0
0 1H106 F
1 1607 73 1321 1354 0
2.498 0
0 1H130 S
1 1638 55 1368 1383 0
1.096 0
0 1H130 F
1 1582 55 1331 1360 0
2.179 0
0 2H051 S
1 1539 99 1259 1297 0
3.018ý 0
0 2H051 F
1 1643 99 1329 1321 0
-0.602 0
0 2H054 S
1 1582 24 1335 1376 0
3.071 0
0 2H054 F
1 1589 24 1340 1363 0
1,716 0
0 2H078 S
1 1643 22 1376-1423 0
3.416 0
0 2H078 F
1 1632 22 1369 1373 0
0,292 0
0 2H111 S
1 1607 70 1338 1386 0
3,587 0
0 2H111 F
1 1577 70 1318 1336 0
1,366 0
0 3H005 S
1 1579 53 1315 1402 0
6.616 0
0 3H005 F
1 1562 53 1304 1356 0
3.988 0
0 3H032 S
1 1545 65 1285 1345 0
4.669 0
0 3H032 F
1 1632 65 1343 1365 0
1.638' 0
0 1H091 1H091 1Hi12 1H112 2H093 2H093 2H129 2H129 2H036 2H036 2H048 2H048 1 H043 1 H043 1 H049 1 H049 1H091 1 H091 2H129 2H129 1H130 1H130 1H127 1H127 S
F S
F S
F S
F S
F S
F S
F S
F S
F S
F S
F S
F 5
5 5
5 5
5 5
5 5
5 5
5 10 10 10 10 10 10 10 10 10 10 10 10 1550 1612 1579 1542 1607 1589 1558 1553 1637 1644 1643 1620 5
5 55 55 90 90 68 68 10 10 11 11 1634 1553 1610 1567 1550 1612 1558 1553 1638 1582 1610 1542i 2
2 31 31 5
5 68 68 55 55 6
6 1310 1386 1318 1280 1294 1302 1293 1289 1359 1364 1364 1345 1312 1329 1281 1270 1276 1270 1345 1213 1384 1381 1380 1338 1356 1306 1325 1298 1303 1341 1287 1284 1345 1310 1356 1314 1331 132(
1271 1331 1311 1281 1321 126!
1331 1291 1341 1311 15901 - Average Initiai 13161- - Average Predicted (End-of-Life) 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 0.69897 20.388 0.1531
-4,113
-2,807
-0781
-1.3911
-2.4581 4.022i
-5.896 1.840 1.246 1,173!
-0.520
-1.917ý 1.072!
-4,1511 2.465 0.537
-4.549 2.564
-1,480
-1,115
-1.527
-1.180
-0.304 27.611 0.10671
-2.87455
-1.96221
-0.54607
-0.97229
-1.71790 2.81102
-4.12116 1.28582 0.87115 0.81991
-0.36378
-1.91740 1.07198
-4,15094 2.46533 0.53722
-4.54884 2.56410
-1.47975
-1.11524
-1.52672
-1.17994
-0.30441
-16.248 0.48856 0.48856 0,48856 0.48856 0.48856 0.48856 0,48856 0.48856 0.48856 0.48856 0.48856 0.48856 1
1 17.863 Number of liftoff tests: N =42 See page 1 of this attachment for an explanation of columns 1 through 7, and page 3 of this attachment for an explanation of columns 8 through 11.
Attachment NOC-AE-02001439 Page 7 of 10 Supplementary Table S-4: Hoop Tendons (U2)
Tendons Time Liftoff Force (Kips)
Regression Line Parameters Tendon End (yr)
Initial Elastic Loss Predicted Measured X
f Y,
Xi YX 1
2 3
4 5
6 7
8 9
10 11 1H094 S
1 1535 55 1289 1283 0
-0.465 0
0 1H094 F
1 16201 55 13451 1335 0
-0.743 0
0 1H112 S
1 15351 56 1305!
1274 01
-2375 0
0 1H112 F
1 15801 56 1343 1303 0
-2978 0
0 1H124 S
1 1580 55 1343 1312 0'
-2308 0
0 1H124 F
1 15801 55 1343 1337 0
-0447 0
0 2H033 S
1 1520 49 1292 1216 0
-5882 0
0 2H033 F
1 15501 49 1302 1354 0
3994 0
0 2H075 S
1
- 1600, 43 1344 1394 0
3720 0
0 2H075 F
1 16001 43 1344 1398 0
4018 0
0 2H105 S
1 15401 39 1309 1418 0:
8327 0
0 2H105 F
1
- 1580, 39 1327 1400 0
5501 0
0 3H005 S
1 1580 101 1296 1355 01 4552 0
0 3H005 F
1 1550 101 12711 1375 0
8.183 0
0 3H029 S
1 1585*
97 1300 1392 01 7077 0
0 3H029 F
1 1550 97 1271i 1319 0
3 777 0
0 3H056 S
1 1570 65 1319!
1361 0
3184 0
0 3H056 F
1 1580 65 1311 1346 0
2670 0
0 1H055 S
5 1550 3
1310 1325 0.69897
] 145 0-80035 0.48856 1H055 F
5 1540 3
1301 1298 0.69897
-0231
-0.16118 0.48856 1H106 S
5 1580 56 1304 1308 0.69897 0307 0-21441 0.48856 1H106 F
5 1570 56 1295 1251 0.69897!
-3398
-2.37488 0.48856 2H018 S
5 1540 10 1301' 1421 0.698971 9224 6.44707 0.48856 2H018 F
5 1620 10 1353 1352 0.69897i
-0074
-0.05166 0.48856 2H045 S
5 1540 47 1278 1356 0.69897!
6 103 4.26601 0.48856 2H045 F
5 1570 47 1295 1300 0.69897 0386 0.26987 0.48856 2H075 S
5 1600 43 1320 1324 0.69897!
0303 0.21181 0.48856 2H075 F
5 1600 43 1320 1338 0.698971 1 364 0.95314 0.48856 3H050 S
5 1610 64 1312 1336 0.69897 1 829 1.27860 0.48856 3H050 F
5 1630 64 1337 1323 0.69897
-1 047
-0.73191 0.48856 2H033 2H033 2H036 2H036 2H030 2H030 S
F S
F S
F 10 10 10 10 10 10 1520 1550 1600 1570 1550 1570 49 49 13 13 12 12 1258 1277 1329 1311 1299 1311 1196 1280 1290 1310 1280 1320 15831- - Average Initial 11 1 138
-4928 0235
-2935
-0076
-1.463 0686 47.233
-4.92846 0.23493
-2.93454
-0.07628
-1.46266 0.68650 2.641 1
1 1
1 1
1 11.863 1316 - - Average Predicted (End-of-Life)
Number of liftoff tests: N = 36 See page 1 of this attachment for an explanation of columns 1 through 7, and page 3 of this attachment for an explanation of columns 8 through 11.
Attachment NOC-AE-02001-439 Page 8 of 10 Supplementary Table S-5: TREND
SUMMARY
GROUP Ul-Hoop Ul-Vert U2-Hoop U2-Vert Sum X, 20.388 11.592 14.388 5.592 Sum YV 27.611 19.632 47.233/
39.661 Sum X1 Y,
-16.248 15.139 2.6411 20.573 Sum X1 2
17.863 9.908 11.863 3.908 N
42 22 36; 16 X-Mean 0.485 0.527 0.400 0.349 Y-Mean 0.657 0.892 1.312ý 2.479 Beta
-3.722 1.262
-2.656 3.435 Alpha 2.464 0.228 2.374!
1.279 Trend* (Yr.)
% DEVIATION FROM PREDICTED LIFTOFF 1
2.46 0.23 2.37 1.28 5
-0.14 1.11 0.52 3.68 10
-1.26 1.49
-0.28 4.71 15
-1.91 1.71
-0.75 5.32 20
-2.38 1.87
-1.08 5-75 25
-2.74 1.99
-1.34 6.08 30
-3.03 2.09
-1.55 6.35 35
-3.28 2.18
-1.73 6.58 40
-3.50 2.25
-1.88 6.78
- Trend Line: X = Log(time)
Y = Alpha + (Beta)(X)
Attachment NOC-AE-02001439 Page 9 of 10 Revised Figure 1: Trend Lines of Lift-Off Test Results (Years 1, 5, and 10) 8" 6
4-6 U)
U,~~~U i
1__
"e,,0
- 2.
E o
-4 k Year of Plant Life
Attachment NOC-AE-02001439 Page 10 of 10 Figure 2: Trendlines of Lift-Off Test Results (Years 1, 5, and 10)
Year of Plant Life (Logarithmic) 8 6
4 2
0
-2 EU En EU
'3:
-o EU 4-.
U EU I
2 0
0 EU EU 0
-4
-6