ELV-00650, Discusses Proposed Mods to Settlement Monitoring Program. Program Includes Specific Provisions for Reading of Settlement Markers & for Engineering Evaluation of Settlement data.W/45 Oversize Drawings
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l EL50'0'653' U "" N ",.m June 23, 1989 1497n uw,u onnm U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C.
20555 PLANT V0GTLE - UNITS 1, 2 l
NRC 00CKETS 50-424, 50-425 OPERATING LICENSES NPF-t,8, NPF-81 SETTLEMENT MONITORING PROGRAM
References:
1.
Letter GN-1368, dated May 22, 1987 2.
Letter SL-3002, dated August 3,1987 3.
Letter GN-1398, dated September 22, 1987 4.
NRC letter, dated October 20, 1987, M. A. Miller to J. P. O'Reilly Gentlemen:
The settlement of safety-related structures at the Vogtle Electric Generating Plant is monitored through an established program as defined in FSAR Section 2.3.4.13.2.
This program includes specific provisions for the reading of settlement markers and for the engineering evaluation of settlement data.
In October 1987, approval was obtained from the NRC staff to reduce the reading frequency from 60 days to six months for 58 plant settlement markers, most of which are located in Unit 1 structures.
The remaining markers continue to be read at 60-day intervals.
However, we have reviewed our settlement program and determined that further modifications can be made which will continue to provide ample data for settlement evaluation while reducing the amount and difficulty of the work Involved.
The proposed modifications to the settlement monitoring program are as follows:
o Change the reading frequency on 56 of the most stable markers on the Unit 2 side (west of the plant centerline) ard nine additional markers on the Unit 1 side, from 60-day intervals to six-month intervals.
Affected markers are located in completed areas where j
neither concrete placement nor backfilling have recently occurred.
o Discontinue the raadings of 5 markers associated with the radwaste solidification building.
o Discontinue the engineering review of basemat deformation and structural tilt.
b mweajs I:
8906280321 890623 FDR ADOCK 05000424 I0 MU g
Georgia Power d U. S. Nuclear Regulatory Commission ELV-00650 Page Two The justification for the proposed reading frequency modification is as follows:
1.
Readings of the affected markers (see attached Table 1) have been esser. lally stable for. at least 12 nonths.
This can be verified by reviewing the settlement drawings provided with tle attached Appendix A.
These drawings, which show the graphical plot v settlement as a function of time, demonstrate that the settlement of these markers has essentially leveled off.
A comparison of the actual measured total settlements of the major seismic Category I structures to the predicted maximum values is included for information in the attached Figure 1.
2.
The attached sketch, SK-2-C-330, provides a plan vien of the major power block structures and shows those markers whose reading frequency is proposed to be changed from 60-day intervals to 6-month intervals by this request, as well as those whose reading frequency has already been changed by our previous request.
Most nf the Unit 1 markers and a few of the Unit 2 markers which are shown were approved by the NRC staff in October 1987 (References 1, 2, 3 and 4). The placement of all backfill, concrete and equipment loads is complete with the exception of the high density fuel racks and water loads in the west pool of the fuel handling building which are forecast for August 1989.
3.
Where the affected markers have been used to calculate differential settlement between structures, the gross differential settlement is low. These low differential values are shown in Table 2 (also attached). These differential values are typically calculated from the date both markers were first monitored, not merely subsequent to the installation of piping.
4.
The differentials which have been measured are substantially less than the predicted differentials for which the piping has been analyzed.
It can be seen from Table 2 that in the unlikely event l
that relatively substantial differentials were to develop in the future at these interfaces, enough margin remains so that piping would not be overstressed.
The above data demonstrate that no changes are likely to occur within a six month period which would affect our evaluation of the settlement data.
The radwaste solidification building is not used, nor is it planned to be used in the near future. All pipes which pass from the bu. 'ing to the tunnel are not utilized and have been abandoned in place.
Therefore, we propose to discontinue the readings for all markers associated with the radwaste solidification building, i.e., markers 158,159,160 and 161 in the radwaste solidification building and marker 155 in the radwaste tunnel.
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' Georgia Power n U. S. Nuclear Regulatory Commission ELV-00650 Page Three These 5 markers have never shown any unusual settlement and their settlement has stabilized, as can be seen from the drawings of Appendix A.
Although we plan to discontinue their readings, the markers will be retained so that they will be available if readings are required at some future date.
Basemat deformation due to differential settlement within a structure is addressed by developing contours of equal measured settlement for the 1arge power block structures and estimating the amount of basemat deformation relative to the tilt of the structure as a whole.
This is done by determining the maximum net slope of the deflection curve ((/L) relative to the structure tilt for key sections through the basemat and comparing this value to published criteria. Deformations represented by a maximum net slope of less than 1/670 are so small that no further review is required (reference FSAR Question 241.18).
An example of the calculation of the maximum ef/L ratio for a structure, in this case the auxiliary building, is shown in Figure 2.
This is an update of FSAR Figure 241.1 8-3.
The maximum cf /L values determined for applicable VEGP structures as of January,1989 are as follows:
Auxiliary Building 1/3917 Fuel Handling Building 1/2773 Cor.crol Building 1/3720 The largest 8/L ratio is 1/2773 for the fuel handling building. This is well below the value of 1/670 previously discussed.
Therefore, the effects of differential settlement on the VEGP structures are negligible and further review of basemat deformation and structural tilt is not required.
It should be noted that only those structures whose size resulted in the installation of a large number of markers were suitable for the development of contours. However, since the effects of differential settlement on large structures is negligible and the data typically indicate that the remaining l
structures are settling unifonnly, the effects of differential settlement on the remaining structures is also negligible.
We would appreciate your timely review and concurrence of these changes to our settlement monitoring program.
Sincerely, id, b /[brsE-r--
W. G. Hairston, III
GeorgiaFo ver d i
U.' S. Nuclear Regulatory Commission ELV-00650 Page Four WGH,III/ JAB /gm Attachment xc: Georgia Power Company Mr. C. K. McCoy Mr. G. Bockhold, Jr.
Mr. R. M. Odom Mr. J. P. Kane NORMS tl. S. Nuclear Regulatory Commission Mr. S. D. Ebneter, Regional Administrator Mr. J. B. Hopkins, Licensing Project Manager, NRR Mr. J. F. Rogge, Senior Resident Inspector, Vogtle
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FIGURE 1 SETTLEMENT OF UNITS 1 AND 2 POWER BLOCK STRUCTURES
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TABLE 1 LIST OF MARKERS WHOSE READING FREOUENCY WIll, BE REDQQED FROM ONCE EVERY 60 DAYS TO ONCE EVERY 6 MONTHS l
Marker No'.
I.ocation - Unit 1 140-NSCW Tower and Valvehouse a
142 a
1003 a
1005 193 Category I Tunnels a
194 192 Category I Tanks 133 Auxiliary Building a
136 Marker No.
Location - Unit 2 200 Turbhe Eldg. (Non Cat. I) a 20'.
- .03 a
104 a
205
=
262 a
263 264 Mainsteam Tunnel (Non Cat. I) a 265 a
267 219 Control Building a
221 a
222 a
224 a
266 a
269 241 Category I Tunnels a
268 270 a
271 a
272 a
273 a
274 a
279 280 a
288
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s TABLE 1 (Continued)-
LIST OF MARKERE UHOSE READING FREOUENCY WILL BE REDUCED FROM..ONCE EVERY 60 DAYS TO ONCE EVERY 6 MONTHS Marker No.
Imcation - Unit 1 289 Category 1 Tunnels 291 292 294.
234-Auxiliary Building 225 Containment Building 226 427 247 Auxiliary Feedwater Pumphouse 242 249 Diesel Generator Building 250-251' 252 253 Diesel Fuel Oil Storage Tank Pumphouse 254 295 296 239 Category I Tanks 240 255 256 290 242 NSCW Tower and Valvehouse 246 259 297 298 l
299 2001 I
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c TABLE 2 IETrarACEE TO BE READ AT RRhUCED (6-MONTH) pmHENCY (Based On Readings Taken In January 1989)
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t Minimum Actual Differential Used Differential")
In Piping Design Marker Interface structure interface Unch)
(inch) 192/193 Reactor Makeup Water Storage 0.03 0.5 Tank / Tunnel IT2B 194/140 Tunnel IT25, 5B/NSCW Valvehouse 0.04 0.5 0.01 0.5 194/1003 222/226 Control / Containment 0.02 0.6 0.19 0.6 222/427 0.11
- 0.4 224/225 289/299-Tunnel 2T25,5B/NSCW Valvehouse 0.07 0.5 0.06 0.5 289/244 290/291 Reactor Makeup Water Storage 0.09 0.5 Tank / Tunnel 2T2B 288/292 Tunnel 2T2B/ Tunnel 2T2B 0.02 0.3 241/297 Tunnel 2T2A,5A/NSCW Valvehouse 0.10 0.5 0.07 0.5 241/2h 293/294 Tunnel 2T2A,5A/ Tunnel 2T2A,5A 0.01 0.3 279/280 Tunnel 2T3A/ Tunnel 2T2A,5A 0.05 0.3 273/274 Tunnel 2T3B/ Tunnel 2T3B 0.01 0.3 252/271 Diesel Gen. Bldg / Tunnel 2T3A 0.07 0.5 249/272 Diesel Gen. Bldg / Tunnel 2T3B 0.10 0.5 252/296 Diesel Gen. Bldg / Diesel Fuel Oil 0.06 0.5 Storage Tank Pumphouse 251/254 Diesel Gen. Bldg / Diesel Fuel Oil 0.12 0.5 Storage Tank Pumphouse 251/270 Diese1 % n. Bldg / Tunnel 274A,4B 0.16 0.5 0.14 0.5 250/270 248/255 Aux. Feedwater Pumphouse/ Condensate 0.12 0.5 Storage Tank 247/256 Aux. Feedwater Pumphouse/ Condensate 0.00 0.5 Storage Tank
'268/269 Tunnel 2T4A,4B/ Control 0.17 0.6 266/267 Control /Mainsteam Tunnel 0.25 0.6 265/204 Mainsteam Tunnel / Turbine 0.13 0.5 0.23 0.5 264/263 0.02 0.5 264/262 (1) Calculated from the first date that both markers were monitored except for uarker interface 224/225.
(2) Calculated from pipe installation date.
p...*I APPENDIX A LIST OF SETTLEMENT DRAWINGS li Drawina No.
' Revision No.
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OVERSIZE DOCUMENT PAGE PULLED SEE APERTURE CARDS NUMBER OF OVERSIZE 'PAGES FILMED ON APERTURE CARDS M APERTURE CARD /HARD COPY AVAILABLE FROM QECORDS. AND REPORTS MANAGEMENT BRANCH l
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