View source for NOC-AE-02001439, Response to Request for Additional Information, Revised Request for Approval of Alternative Approach for Containment Concrete & Tendoc Surveillance (RR-ENG-37)

{{Adams
| number = ML030210116
| issue date = 01/06/2003
| title = Response to Request for Additional Information, Revised Request for Approval of Alternative Approach for Containment Concrete & Tendoc Surveillance (RR-ENG-37)
| author name = Jordan T
| author affiliation = South Texas Project Nuclear Operating Co
| addressee name = 
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000498, 05000499
| license number = NPF-076, NPF-080
| contact person = 
| case reference number = G25, NOC-AE-02001439, RR-ENG-37
| document type = Letter type:NOC
| page count = 12
| project = 
| stage = Response to RAI
}}

=Text=
{{#Wiki_filter:Nuclear Operating Company South T*rs ,*/eEkdtC G             P0 5ar 2S S*feaenhSon      HadsmrtA, lcea 77453                                 *A A January 6, 2003 NOC-AE-02001439 File No.: G25 10CFR50.55a 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 XI, 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                  A. H. Gutterman, Esquire Regional Administrator, Region IV   Morgan, Lewis & Bockius LLP U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400     L. D. Blaylock/W. C. Gunst Arlington, Texas 76011-8064         City Public Service U. S. Nuclear Regulatory Commission Mohan C. Thadani Attention: Document Control Desk    U. S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike                R. L. Balcom Rockville, MD 20852                 Texas Genco, LP Richard A. Ratliff                  A. Ramirez Bureau of Radiation Control         City of Austin Texas Department of Health 1100 West 49th Street               C. A. Johnson Austin, TX 78756-3189               AEP Texas Central Company Cornelius F. O'Keefe                Jon C. Wood U. S. Nuclear Regulatory Commission Matthews & Branscomb P. O. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 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 and2, it is unclear what the actual measuredand predictedtendon forces are. The licensee is requestedto 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 duringeach priorinspections.
In the Figure,the licensee is requestedto show:
(1) The trend lines (separately,for each Unit, and for U and hoop tendons) based on the inspectionsperformed, (2) Actual measured forces as points above and below the trend lines, and (3) Predictedaverage tendon forces at 40 years.
The licensee is also requested to provide a summary of the method used to construct the trendlines.
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 I 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 Unes The trend line is calculated using linear regression analysis. The trend is a straight line, represented by the equation:
Y=a + A3X, where the variables X and Y are 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(1), Log(5), and Log(110), 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, itfollows 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 - ix,

Attachment NOC-AE-02001439 Page 3 of 10 Zx,y,-.x
                 '     2 axi -n.x.2 i=1 in L            in where x = -. X xi, y =          F y, and n = number of data points in the group.
n    i            i=1 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)]I(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 + Log(7)
                     = 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:
a 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 (U1)
V2 S         1          15811                   1376       1402         0      1.890           0       0 V2 F         1          16111                   1391       1439         0      3.451           0       0 V4 S          1          16222                   1401       1400         0     -0.071           0       0 022        1352       1343         0     -0.66            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    1.81214  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    0.92307  0.48856 V242  F             5          1608             5      1367       1397  0.69897       2.195    1.53495  0.48856 V248  S             5          1603             9      1354       1359  0.69897       0.369    0.25811  0.48856 V248  F             5          1608             9      1359       1382  0.69897       1.692    1.18395  0.48856 V126  S            10          1598            11      1348       1340         1     -0.593   -0.59347        1 V126  F            10          1621            11      1362       1380         1      1.322    1.32159        1 V129  S            10          15339           47      1286       1290         1      0.31     0.31104
                                                                                                .1            1 V14   F             5          1631            47      1333       1320         1     -0.975   -0.97524        1 V-26  S            10          1598            12      1379       1380         1      0.073    0.07252        1 V230  F            10          1596            -2      1354       1430         1      5.613 5.61300           1
____           9 0040g'     ti                    11.592    19.632 115.139 19.908
___________     ____              ge    ed)'   (E) 0If~      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) ia E         P     e  MeOse V110  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      1410      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 V110  S         5        1605            25      1348      1412  0.69897     4.748 3.31855    0.48856 V110  F         5        1605            25      1348      1362  0.69897      1.039 0.72593   0.48856 V203  S         5        1610            13      1360      1415  0.69897     4.044 2.82672    0.48856 V203  F         5        1620            13      1361      1407  0.69897     3.380 2.36243    0.48856 V221  S         5        1580             -2     1351      1479  0.69897     9.474 6.62237    0.48856 V221  F         5        1630             -2     1394      1452  0.69897     4.161 2.90820    0.48856 V233  S         5        1580            29      1343      1348  0.69897     0.372 0.26023    0.48856 V233  F         5        1540            29      1309      1338  0.69897     2.215 1.54852    0.48856
_ _  _595        *]*g 't5.592                         39.661    20.573   3.908 1 5eg~ Pe-oL                      umer 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.

Attachment NOC-AE-02001439 Page 6 of 10 Supplementary Table S-3: Hoop Tendons (Ul)
Ten on                                0im                               Rers o         i    ~r~t 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     3.018          0        0 2H051      F          1      1643            99      1329      13211          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      S          5      1550             5      1310      1312    0.69897      0.153 0.10671    0.48856 1H091      F          5      1612             5      1386      1329    0.69897     -4.113 -2.87455   0.48856 1H112      S          5      1579            55      1318      1281    0.69897, -2.807 -1.96221      0.48856 1HI12      F          5      1542            55      1280      1270    0.69897     -0.781 -0.54607   0.48856 2H093      S          5       1607           90      1294      1276    0.69897     -1.391 -0.97229   0.48856 2H093      F          5       1589           90      1302      1270    0.69897     -2.458 -1.71790   0.48856 2H129      S          5       1558           68      1293      1345    0.69897      4.022 2.81102    0.48856 2H129      F          5       1553           68      1289      1213    0.69897     -5.896 -4.12116   0.48856 2H036      S          5       1637           10      1359      1384    0.69897       1.840 1.28582   0.48856 2H036      F          5       1644           10      1364      1381    0.69897       1.246 0.87115   0.48856 2H048      S          5       1643           11      1364      1380    0.69897       1.173 0.81991   0.48856 2H048      F          5       1620           11      1345      1338    0.69897     -0.520 -0.36378   0.48856 1H043      S         10       1634            2      1356      1330           1 -1.917 -1.91740             1 1H043      F         10       1553            2      1306      1320           1      1.072 1.07198          1 1H049      S         10       1610           31      1325      1270           1 -4.151 -4.15094             1 1H049      F         10       1567           31      1298      1330           1     2.465 2.46533           1 1H091      S         10       1550            5      1303      1310           1     0.537 0.53722           1 1H091     F         10       1612            5      1341      1280           1 -4.549 -4.54884             1 2H129      S         10       1558           68      1287      1320           1     2.564 2.56410           1 2H129      F         10       1553           68      1284      1265           1 -1.480 -1.47975             1 1H130     S         10       1638           55      1345      1330           1 -1.115 -1.11524             1 1H130     F         10       1582           55      1310      1290           1 -1.527 -1.52672             1 1H127     S         10       1610            6      1356      1340           1 -1.180 -1.17994             1 41H1i27    F         10       15421           6      1314      1310           1 -0.3041 -0.30441            1
__       I 20.388     27.611 1 -16.248 1 lumber of liftoff tests: N =42 17.863 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) 1H094    S          1       1535           55      1289       1283         0     -0.465             0         0 1H094    F          1       1620           55      1345       1335         0     -0.743             0         0 1H112    S          1       1535           56      1305       1274         0     -2.375             0         0 1H112    F          1       1580           56      1343       1303         0     -2.978             0         0 1H124    S          1       1580           55      1343       1312         0     -2.308             0         0 11H124   F          1       1580           55      1343       1337         0     -0.447             0        0 2H033    S          1       1520           49      1292       1216         0     -5.882             0        0 2H033    F          1       1550           49      1302       1354         0       3.994            0        0 2H075    S          1       1600           43      1344       1394         0       3.720            0        0 2H075    F          1       1600           43      1344      1398          0       4.018            0        0 2H105    S          1       1540           39      1309       1418         0       8.327            0        0 2H105    F          1       1580           39      1327      1400          0       5.501            0        0 3H005    S          1       1580          101      1296      1355          0       4.552            0        0 3H005    F          1       1550          101      1271      1375          0       8.183            0        0 3H029    S          1       1585           97      1300      1392          0       7.077            0        0 3H029    F          1       1550           97      1271      1319          0       3.777            0        0 3H056    S          1       1570           65      1319      1361          0       3.184            0        0 3H056    F          1       1580           65      1311      1346          0       2.670            0        0 1H055    S          5       1550            3      1310      1325    0.69897        1.145    0.80035   0.48856 1H055    F          5       1540            3      1301      1298    0.69897    -0.231      -0.16118   0.48856 1H106    S          5       1580           56      1304      1308    0.69897      0.307      0.21441   0.48856 1H106    F          5       1570           56      1295      1251    0.69897    -3.398      -2.37488   0.48856 2H018    S          5       1540           10      1301      1421    0.69897      9.224      6.44707   0.48856 2H018    F          5       1620           10      1353      1352    0.69897    -0.074      -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      0.386      0.26987   0.48856 2H075    S          5       1600           43      1320      1324    0.69897      0.303      0.21181   0.48856 2H075    F          5       1600           43      1320      1338    0.69897        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    S         10       1520           49      1258      1196          1    -4.928      -4.92846         1 2H033    F         10       1550           49      1277      1280          1      0.235      0.23491         1 2H036    S         10       1600           13      1329      1290          1    -2.935      -2.93454         1 2H036    F         10       1570           13      1311      1310          1    -0.076      -0.07628         1 2H030    S         10       1550           12      1299      1280          1    -1.463      -1.46266         1 2HO3O
*, .vvv F         10
                   ,v 197n           12      1 11      1q20          1      0v,*vv  1  068RR501        1 14.388 1 47.233       [  2.641    11.863 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-02001439 Page 8 of 10 Supplementary Table S-5: TREND 

==SUMMARY==

20.388     11.592     14.388              5.592 27.611     19.632     47.233            39.661
         -16.248     15.139      2.641            20.573 17.863      9.908     11.863              3.908 42       22            36              16 0.485      0.527      0.400              0.349 0.657      0.892      1.312              2.479
          -3.722      1.262     -2.656              3.435 2.464      0.228      2.374              1.279 2.4_6     0.23        2.375             1.28
            -0.14      1.11        0.52*             3.68
           -1!.26      1.49       -0.28              4.71
           -1.91       1.71       -0.75              53
           -2.38       1.87      -1.08               5.75
           -2.74       1.99      -1.34               6.08
           -3.03       2.09      -1.55               6.35
           -3.28       2.18      -1.73               6.58
           -3.50       2.25      -1.88               6.78

Attachment NOC-AE-02001439 Page 9 of 10 Revised Figure.1: Trend Lines of Lift-Off Test Results (Years 1, 5, and 10) 8
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Attachment NOC-AE-02001439 Page 10 of 10 Figure 2: Trendlines of Lift-Off Test Results (Years 1, 5, and 10) 8
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