3F1294-13, Requests for Addl Info Re Fifth Tendon Surveillance Rept
| ML20078S269 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 12/15/1994 |
| From: | Beard P FLORIDA POWER CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 3F1294-13, NUDOCS 9412280199 | |
| Download: ML20078S269 (23) | |
Text
r Flcrida gpygr
- "ra:
i December 15, 1994 3F1294-13 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Request for Additional
Subject:
Fifth Tendon Surveillance Report Information
References:
A. FPC to NRC letter, 3F0294-02, dated February 4, 1994 B. FPC to NRC letter, 3F0894-03, dated August 12, 1994 C. NRC to FPC letter, 3N0994-16, dated September 22, 1994 D. FPC to NRC letter, 3F1194-02, dated November 4, 1994
Dear Sir:
Florida Power Corporation (FPC) conducted the fifth tendon surveillance for Crystal River Unit 3 late last year. The schedule for the surveillance (as it related to operational mode and the timing of the implementation of the Improved Technical Specifications (ITS)) and our past results caused FPC to believe it was prudent to request a change to our previous surveillance requirements.
The review of this change was complicated and ultimately involved the consideration of the existing requirements, those contained in ASME XI-IWL and Regulatory Guide (RG) 1.35.
The NRC granted an amendment to the Technical Specifications (TS) during the performance of the surveillance (Amendment No.148).
The amended interim Technical Specification requirements were based on RG 1.35. In Reference A, FPC committed to provide a report summarizing the results of the surveillance.
Reference B was the report. The report was a standard one siitilar to those that our Architect / Engineer (A/E) had provided to us after past surveillances and was based on the previous requirements.
FPC added a summary to the report that sought to bridge the difference between previous requirements and those required by the interim Technical Specifications.
CRYSTAL RIVER ENERGY COMPLEX
- 15760 W. Power Line Street
- Crystal River
- Florkla 34428-6708 * {904)795-6486
~ ^ 9412200199 941215 ] PDR ADOCK 05000302 P PDR J --- a
c .j U.-S. Nuclear, Regulatory 3F1294-13 Page 2 Reference C was a request for additional information' based ~upon RG 1.35. Please find FPC's: responses to the request for. additional information' contained. in Reference C. We believe this submittal. contains the. complete information requested in Questions No.1, 2, 5 and 6..'The information requested in Question No. 3 will require further discussions between your staff, FPC and our. A/E. We will schedule a telecon or meeting 1 at a mutually. acceptable time to facilitate ' the resolution of this-issue. The information requested by question No. 4 will be incorporated in the reports of future tendon surveillances. We do not believe it will be cost beneficial at this point to develop the requested curves (RG 1.35-format) and we believe sufficient information is available in the existing report .to meet the intent of the surveillance. We appreciate the frank' and constructive - feedback the staff has provided i throughout the review of the TS and the report. Future surveillances. and associated reports will be conducted in a more standard manner as required by the program descriptions contained in the ITS. We apologize for the added complexity that this transition has caused. Sincerely, P. M.- eard,'Jr. Senior Vice. President Nuclear Operations PMB/LVC:ff-i xc: Regional Administrator, Region II l Senior Resident Inspector NRR Project Manager-
U. S. Nuclear Regulatory Commission 3F1294-13 Page 3 NRC QUESTION 1. Item 4.2 of regulatory position 4 in Regulatory Guide (RG) 1.35 Rev. 3, requires the simultaneous measurement of elongation and jacking force during re-tensioning at a minimum of three approximately equally spaced leveis of force between zero and the lock-off force. The information given in Section 7.0 of the report does not contain this detailed information. Please provide the required information. FPC RESPONSE During the Fifth Tendon Surveillance, four tendons were de-tensioned and then re-tensioned; 56V15, D231, 46H29 and 46H47. The requested information regarding simultaneous measurement of elongation and jacking force during re-tensioning at a minimum of three approximately equal spaces of force between and the lock-off force is presented in the enclosed Tables 1 through 11. Tablo I summarizes the location of the data in the VSL report which is available at the site (not included in this submittal). Tables 2 through 11 provide the information requested for each of the. tendons listed above. The information is presented in three tables / tendon with the exception of 56V15 which does not have a shop end or a field end due to the fact of being a vertical tendon. l l
U. S. Nuclear Regulatory Commission 3F1294-13 .Page 4 NRC QUESTION 2. We have reservations about the regression analysis for the trend of each group-of tendons. Instead of using the average of the lift-off forces of the group of tendons in each surveillance, the lift-off forces for all the tendonc in that group for all the five surveillances should be used individually as the basis for the regression analysis. A revised regression analysis should be provided. FPC RESPONSE FPC has plotted the individual lift-off forces for all the tendons in each group (vertical, hoop and dome) for all the five surveillances. A revised regression analysis is provided in revised Figures 6.1, 6.2 and 6.3. However, the resulting regression analysis provided in the revised figures is mathematically identical to the one which was provided to the NRC Staff in Reference A.
J l U. S. Nuclear Regulatory Commission 3F1294-13 J Page 5 NRC QUESTION 3. In Tables 6.1, 6.2 and 6.3, you indicate that the measured lift-off i forces in column 3 are normalized. The reason for such a modification is unclear. It appears that the original lock-off forces as listed in column 2 may need to be normalized. It is the staff's understanding that the purpose of normalization is to take into consideration the effect of elastic shortening as discussed in section 2.1 of RG 1.35.1. This occurs only to the initial lock-off forces of earlier tensioned tendons as they are affected by elastic shortening of concrete caused by other tendons being tensioned later. If this interpretation is not the reason for the normalization, please provide an explanation or make the necessary revision to the applicable portions of the report. The information contained in Appendix B is not understandabic. FPC RESPONSE The Containe #t Tendon Surveillance Program states that normalization :,F che lift-off forces be done and that the average of the normalized measured lift-off force for each group of tendons be compared to that group's established minimum values. Column # 2 of Tables 6.1, 6.2, and 6.3 listed the original lock-off force only for information purposes. Column #3 of such tables lists the as-measured lift-off force during the fifth tendon surveillance. The number in column #3 was then adjusted by a normalizing factor listed in column # 9 of the tables. FPC believes that normalizing the measured lift-off force as our tendon program implementing procedure requires is adequate but we would suggest that a discussion with the NRC Staff would be helpful to clarify the reason for the normalization as well as the calculation of the normalization factors used.
U. S. Nuclear Regulatory Commission 3F1294-13 Page 6 NRC QUESTION 4. The predicted force versus time curves shown in Appendix A for individual tendons are inadequate for the following reasons: (a) with the exception of the control tendon in each group, other tendons for inspection are selected randomly, therefore the curve should be for a group of tendons; and (b) the curves should be established in accordance with RG 1.35.1 denoting the upper bound and lower bound and also the minimum force required for the group of tendons. The tendon forces obtained at each surveillance for the group should be plotted on the graph with these curves for the group. The trending of the tendon forces for the group should be shown on this graph for the group. Please revise the graphs as required. FPC RESPONSE FPC intends to change individual tendons' force curves to adopt the Regulatory Guide 1.35.1 forma' as part of the next surveillance. However, FPC does not see at immediate need in doing so since the present format adequately shows each tendon's force loss with respect to time. It is estimated that the curves could be modified at an expense of approximately Thirty Thousand Dollars, however, FPC does not believe that the value added will justify this expenditure. l 1
U. S. Nuclear Regulatory Commission 3F1294-13 Page 7 NRC QUESTION 5. In Appendix "C" you listed all the tendons and identified each tendon as to its ineffective wires. Since you inspect for a limited random sample of tendons, indicate how you can make the identification since only a few tendons are inspected. FPC RESPONSE The data presented in Appendix "C" represents a compilation of the results of all tendon surveillances to date, not just the most recent one, hence it shows the big picture. FPC is providing a revised Page 2 of Appendix C to incorporate note # 4 with a clarification to that effect. l .)
f l . U. S. Nuclear Regulatory Commission - 3F1294-13 Page 8 NRC QUESTION 6. In Appendix D, Table 0-1 listed the amount of grease added to the l: sheathing of tendons under surveillance. The amount of grease added ranges from 9.5% to as high as 30.5%.. Compared to other plants with similar prestressed concrete containments, this loss of grease is unusually high. - An explanation of why the loss.of grease is among the largest for the two control tendons, D215 and 34V6, should be j given. Justification as given in items 1, 2 and 3 under the table cannot fully account for such large losses. A thorough investigation of this abnormality to' determine its root cause is in order.. FPC RESPONSE The results of the Fifth Tendon Surveillance closely match those of previous surveillances with regards to the amount of bulk. filler I grease replaced. The function of the grease is to prevent corrosion l of the tendon wires and the anchorage components. The successful physical tests run on individual tendon wires, the chemical tests on the grease itself, and the lift-off forces being in the acceptable range show that the tendon system 'is maintaining its integrity. Based on those facts and on the absence of any leakage being detected during the walkdown of the Reactor Building _ performed in Spring 1994 (Refuel 9), FPC concluded that the structural integrity of the tendon system has not been affected. A thorough investigation has not determined a root cause for the abnormality in grease volume. FPC intends to more closely monitor the grease injection procedure in future surveillances as well as to investigate industry experience on this matter. l l I
TABLE 1 1 This page serves as a guide to show which VSL Report values were utilized for cetensioned tendons. Refer to the VSL report for the appropriate enclosures. Actual Observed Force and Elongation Measurement for Retensioned Tendons Force Kips Pressure (psi) Elongation (in.) PTF A B C Step #1 0 E F Step #2 G H I LOF J K L OSF M N O NOTE: Step #1 coincides with the 1/3 level of force between zero and the lock-off force, while Step #2 coincides with the 2/3 level of force between zero and the lock-off force. Pressure readings have been converted to force readings utilizing the individual ram charts as appropriate (provided by VSL). A - Enclosure 29 Row #1 B - Enclosure 29, Row #1-(given pressure) C - Enclosure 29, Row #7 D - Use appropriate RAM chart, Tab #3 of VSL Report. 0 refers to which RAM'was used for a given tendon. E - Enclosure 29, Row #10-F - Enclosure 29, Row #11 G - Use appropriate RAM chart, Tab #3 of VSL Report. 0 refers to which RAM was used for a given tendon. H - Enclosure 29, Row #12 L - Enclosure 21, Row #4 I - Enclosure 29, Row #13 M - Enclosure 29, Row #8 J - Enclosure 21, Row #3 N - Enclosure 29, Row #9 K - Enclosure 21, Row #2 0 - Enclosure 29, Row #14 l
TABLE 2 ~ Tendon I.D.: 56V15 Actual Observed Force and Elongation Measurement for Retensioned Tendons Force Kips Pressure (psi) Elongation (in.) PTF 366 1500 5-1/8" Step #1 600 2730 6-1/2" Step #2 1180 5460 10-1/2" LOF 1577 7280 13-1/2" OSF 1772 8180 15" Total Elongation (actual) - (LOF - PTF) Elongation 1/2" 1/8" 3/8" NOTE: Total elongation as calculated above represents format as requested by NRC. Gilbert / Commonwealth report uses OSF - PTF for total elongation which gives a comparison of elongation to original installation. PTF - Pretensioned Force. This is the force necessary to bring the tendon into a lightly stressed condition to remove slack and seat the buttonheads. This force establishes the base for elongation measurement. LOF = Lock Off Force. This is the force at which the tendon load is transferred ta the shim stack from the ram and is representative of the force at which the tendon lift-off occurred during the monitoring of tendon force. OSF = Overstress Force. This is the force maximum elongation is determined. Step #1 and Step #2 are intermediate data required by subsection 4.2 of RG 1.35.
TABLE 3 "T t Tendon I.D.: D231 (Shop End) Actual Observed Force and Elongation Measurement for l Retensioned Tendons-Force Kips Pressure (psi) Elongation (in.) PTF 359 1500 3-9/16" Step #1 540 2360 3-3/4" Step #2 1050 4730 4-5/16" LOF 1345 6210 6-15/16" OSF 1535 7090 7-7/16" t Total Elongation (actual) = (LOF - PTF) Elongation 15/16" 9/16" = 3-3/8" NOTE: Total elongation as calculated above represents format 'as requested by NRC. - Gilbert / Commonwealth report uses OSF - PTF for total elongation which gives a comparison of elongation to original installation. PTF = Pretensioned Force. This is the force necessary to bring the tendon ) into - a lightly stressed condition to remove slack - and seat the buttonheads. This force establ i shes the base for. elongation measurement. 1 LOF = Lock Off Force. This is the force at which the tendon load is transferred to the shim stack from the ram and.is representative of the force at which the tendon lift-off occurred during the monitoring of tendon force. OSF = Overstress Force. This is the force maximum elongation is determined. l Step #1 and Step #2 are intermediate data required by subsection 4.2 of RG 1.35. 4
TABLE 4 Tendon I.D.: D231 (Field End) Actual Observed Force and Elongation Measurement for Retensioned Tendons Force Kips Pressure (psi) Elongation (in.) PTF 364 1500 0" Step #1 520 1830 0-3/4" Step #2 1025 3660 3-1/4" LOF 1370 4910 6-7/16" OSF 1535 5500 3 3/8" Total Elongation (actual) - (LOF - PTF) Elongation 7/16" - 0" 7/16" NOTE: Total elongation as calculated above represents format as requested by NRC. Gilbert / Commonwealth report uses OSF - PTF for total elongation which gives a comparison of elongation to original installation. PTF = Pretensioned Force. This is the force necessary to bring the tendon into a lightly stressed condition to remove slack and seat the buttonheads. This force establishes the base for elongation measurement. LOF - Lock Off Force. This is the force at which the tendon load is transferred to the shim stack from the ram and is representative of the force at which the tendon lift-off occurred during the monitoring of tendon force. OSF - Overstress Force. This is the force maximum elongation is determined. Step #1 and Step #2 are intermediate data required by subsection 4.2 of RG-1.35.
TABLE 5 TendonI.D.: D231 (Composite Results) Actual Observed Force and Elongation Measurement for Retensioned Tendons Kips Total Elongation (Average of Shop End (Sum of Shop End Force and Field End) and Field End) Step #1 530 4-1/2" Step #2 1038 7-9/16" LOF 1358 13-3/8"
TABLE '6- \\ Tendon I.D.: -46H29 (Shop End) j Actual Observed Force and Elongation Measurement for Retensioned Tendons t Force Kips Pressure (psi) Elongation (in.) PTF 364 1500 2" Step #1 580 2610 2-9/16" Step #2 1150 5230 5-3/16" LOF 1466 6770 6-15/16" OSF 1697 7840 7-3/8" u Total Elongation (actual) - (LOF - PTF) Elongation , 15/16" - 2" 15/16" q NOTE: Total elongation as calculated above represents format as requested by NRC. Gilbert / Commonwealth report uses OSF - PTF for total elongation which gives a comparison of elongation to original installation. PTF - Pretensioned Force. This is the force necessary to bring the tendon into a lightly stressed condition to remove slack and seat the buttonheads. This force establishes the base for elongation measurement. LOF - Lock Off Force. This is the force at which the tendon load is transferred to the shim stack from the ram and is representative of the force at which the tendon lift off occurred during the monitoring of tendon force. OSF - Overstress Force. This is the force maximum elongation is determined. Step #1 and Step #2 are intermediate data required by subsection 4.2 of RG 1.35. 1
TABLE 7 Tendon I.D.: 46H29 (Field End) Actual Observed Force and Elongation Measurement for Retensioned Tendons Force Kips-Pressure (psi) Elongation (in.) PTF 366 1500 3-1/2" Step #1 575 2020 4-3/8" Step #2 1125 40S0 5-3/4" LOF 1466 5250 7" OSF 1697 6070 7-3/8" Total Elongation (actual) - (LOF - PTF) Elongation - 7" 1/2" 1/2" NOTE: Total elongation as calculated above represents format as requested by NRC. Gilbert / Commonwealth report uses OSF - PTF for total elongation which gives a comparison of elongation to original installation. PTF = Pretensioned Force. This is the force necessary to bring the tendon into a lightly stressed condition to remove slack and seat the buttonheads. This force establishes the base for elongation measurement. LOF - Lock Off Force. This is the force at which the tendon load is transferred to the shim stack from the ram and is representative of the force at which the tendon lift-off occurred during the monitoring of tendon force. OSF - Overstress Force. This is the force maximum elongation is determined. Step #1 and Step #2 are intormediate data required by subsection 4.2 of RG 1.35.
TABLE 8 1 Tendon I.D.: 46H29 (Composite Results) Actual Observed Force and Elongation Measurement for Retensioned Tendons Kips Total Elongation (Average of Shop End (Sum of Shop End Force and Field End) and Field End) Step #1 578 6-15/16" Step #2 1138 10-15/16" LOF 1466 13-15/16" p
TABLE 9 T Tendon I.D.: 46H47 (Shop End) Actual Observed Force and Elongation Measurement for Retensioned Tendons Force Kips Pressure (psi) Elongation (in.) PTF 364 1500 3-1/16" Step #1 590 2600 3-11/16" Step #2 1180 5200 5-1/4" LOF 1447 6680 6-3/32" OSF 1688 7800 6-1/8" Total Elongation (actual) - (LOF - PTF) Elongation 3/32" 1/16" 1/32" NOTE: Total elongation as calculated above represents format as requested PTF for total by NRC. Gilbert / Commonwealth report uses OSF elongation which gives a comparison of elongation to original installation. PTF - Pretensioned Force. This is the force necessary to bring the tendon into a lightly stressed condition to remove slack and seat the buttonheads. This force establishes the base for elongation measurement. 1 LOF - Lock Off Force. This is the force at which the tendon load is transferred to the shim stack from the ram and is representative of the force at which the tendon lift-off occurred during the monitoring of tendon force. OSF = Overstress Force. This is the force maximum elongation is determined. Step #1 and Step #2 are it'ermediate data required by subsection 4.2 of RG 1.35.
TABLE 10 Tendon I.D.: 46H47 (Field End) Actual Observed Force and Elongation Measurement for Retensioned Tendons Force Kips Pressure (psi) Elongation (in.) PTF 363 1500 2-1/4" Step #1 565 2010 3" Step #2 1120 4030 5" LOF 1491 5340 6-7/8" OSF 1688 6040 7-1/8" ] Total Elongation (actual) = (LOF - PTF) Elongation 7/8" 1/4" 5/8" NOTE: Total elongation as calculated above represents format as requested i Gilbert / Commonwealth report uses OSF - PTF for total by NRC. elongation which gives a comparison of elongation to original installation. PTF = Pretensioned Force. This is the force necessary to bring the tendon into a lightly stressed condition to remove slack and seat the buttonheads. This force establishes the base for elongation measurement. LOF - Lock Off Force. This is the force at which the tendon load is transferred to the shim stack from the ram and is representative of the force at which the tendon lift-off occurred during the monitoring of tendon force. t OSF - Overstress Force. This is the force maximum elongation is determined. l Step #1 and Step #2 are intermediate data required by subsection 4.2 of RG 1.35. 4
1 TABLE 11 Tendon I.D.: 46H47 (Composite Results) Actual Observed Force and Elongation Measurement for Retensioned Tendons Kips Total Elongation (Average of Shop End (Sum of Shop End Force and Field End) and Field End) Step #1 578 6-11/16" Step #2 1150 10-1/4" LOF 1469 12-31/32"
FPC - Crystal River Unit #3 FIGURE 6.1 Tendon Surveillance Prograrn .....an. As Force h s.~.atance Dome Group Trend of Losses 00000 En. Required Avg. Force EME AFTER AVERAGE DKiE OF CONCRETE DOME PLACEMENT (YEARS) 10 3 3 s e a e 2 3 1700 I 1600-G ~ 8 x x v 1500-- g N w E ~ z N Og1400- ~% s 1300 1215 Kips c 0 0 0 0 1200 l l l l l l 12/08/94 1 s s to 15 20 25 30 35 40 SCHEDULED SURVEILLANCE PERIOD (YEARS AFTER SIT)
1 FIGURE 6.2 FPC - Crystal River Unit g3 ""7~. M Forces in Swveinence
- A Tendon Surveillonce Program
,./ Hoop Group Trend of Losses TIME AFTER AVERAGE DATE OF CONCRETE WALL PLACEMENT (YEARS) 1 10 1 3 4 5 0 7 5 e 1 3 4 S 1700 + t 1600 a s G ~ s N a. N* N 52 N v 1500-e U x o s w g \\ 5 x .Q 1400 N ~ N ~ 1300 l 1252 Kips m e t gT I lll ~ l l l l l l 1200 l 12/08/94 i s s to is 20 25 so as 40 SCHEDULED SURVEILLANCE PERIOD (YEARS AFTER SIT) l l
^ a _s FPC - Crystal River Unit #3 nGURE 6.3 Tendon Surveillance Program - An mi rarces w sam. Vertical Group Trend of Losses eseso win. Required Aq. force TIME AFTER AVERAGE DATE OF CONCRETE WALL PLACEMENT (YEARS) 10 1 a m 2 4 s e i 1800 + t e + ~ 1 e e ? %( 1600 _ I N x a s n. ~ E v us ~ O 0 1400 z O O b 1200 1149 Kips c 0 0 0 0 1000 --- 8 3 5 io is to 25 so ' as e 12/08/94 SCHEDULED SURVEILIANCE PERIOD (YEARS AFTER SIT)
- M AFTWWEI C INEITECTIVE WIRE
SUMMARY
p., 3 UPDATED TO FIFTH SURVEILLANCE l Acceptance Criteria 1. Maximum of 8 ineffective wires per tendon. 2. Maximum of 3% ineffective wires per 10 consecutive tendons. i 3. Maximum of 2% ineffective wires per group. The vertical tendons group consists of one stressing sequence quadrant of 36 tendons. The dome tendons group consists of one series layer of 41 tendons, i.e. D100, D200 & D300 groups. The hoop tendons group consists of one side of a buttress or 47 tendons. The results of all tabulated data are summarized as follows: Tendon Groun Maxfrendon Max /10 Tendons Max / Group Domes Actual 7 (Note 1) 30 67 Allowable 8 49 134 Verticals Actual 6 21 37 Allowable 8 49 117 Hoops Acual 6 18 49 Allowable 8 49 153 Netts - 1. Dome tendons D-217 and D-233 with 16 and 12 ineffective wires respectively exceed the 8 wire maximum per tendon but were previously accepted for that condition. These two tendons are reduced force dome tendons and it was determined that the high number of ineffective wires was due to unseating as a result of the reduced tensioning force in the tendons. See Ineffective Wire Summary, Update 2, 8/14/78, for additional information. 2. The calculation for the ten consecutive tendons for the last nine tendons was performed by using the data from first tendons at the top of the listing. 3. Maximum wires per group are noted on the tendon group sheets. 4. Tabulated data on following pages represents composite information for all tendon surveillances to date. - GILBERT / COMMONWEALTH, INC - h- .}}