L-2015-063, In-Service Inspection Plans Fourth Ten-Year Interval Unit 2 Relief Request 2 RAI Reply

In-Service Inspection Plans Fourth Ten-Year Interval Unit 2 Relief Request 2 RAI Reply

ML15076A193
Person / Time
Site:	Saint Lucie
Issue date:	03/05/2015
From:	Katzman E Florida Power & Light Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-2015-063
Download: ML15076A193 (11)

Text

a March 5, 2015 PPL. L-2015-063 10 CFR 50.4 10 CFR 50.55a U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re: St. Lucie Unit 2 Docket Nos. 50-389 In-Service Inspection Plans Fourth Ten-Year Interval Unit 2 Relief Request 2 RAI Reply

References:

1. FPL Letter L-2014-252 dated August 1, 2014, In-Service Inspection Plans Fourth Ten-Year Interval Unit 2 Relief Request 2, Accession No. ML14224A010.

2. NRC Request for Additional Information dated January 14, 2015, Accession No. ML15015A667.

On August 1, 2014, pursuant to 10 CFR 50.55a(a)(3)(ii), Florida Power & Light (FPL) requested an alternative to the requirements of ASME Boiler & Pressure Vessel Code,Section XI, paragraph IWB-3132.2, "Acceptance by Repair/Replacement Activity," because the original alloy 600 small bore nozzles and pressurizer heater sleeves in the St. Lucie Unit 2 reactor coolant system (RCS) have been replaced with alloy 690 nozzles and heater sleeves. Reference 2 forwarded the NRC's request for additional information (RAI). The original due date for the RAI reply was extended by agreement with the NRC St. Lucie Project Manager. The RAI reply is attached to this letter.

Please contact Ken Frehafer at 772-467-7748 if there are any questions about this submittal.

S rell Eric Katzman Licensing Manager St. Lucie Plant Attachment ESK!KWF cc: USNRC Regional Administrator, Region II USNRC Senior Resident Inspector, St. Lucie Units I and 2 Florida Power & Light Company *" c- 1 6501 S. Ocean Drive, Jensen Beach, FL 34957

L-2015-063 Attachment Page 1 of 10

RAI-1

Clarify the reason for submitting this reliefrequest:

a. The affected components listed in Table 1 of Attachment to Relief Request 2 (RR

2) were previously repairedby either the "half-nozzle" or the "sleeve"technique.

The remnant of the flaw(s) in the primary water stress corrosion cracking (PWSSC) susceptible weld or base material was left in service. Therefore, to permit the affected components and remnant flaws to remain in service, a relief is requiredfor the fourth 10-year inservice inspection (ISI) interval.

b. The other small diameter nozzles or heater sleeves in the hot leg piping or the pressurizer may need repair in the fourth 10-year ISI interval; therefore, a contingency relief request is needed.

c. Both a. and b.

d. Other FPL Response to RAI I The reason for submitting Relief Request #2 (RR2) is choice "a." listed above. Submission of RR 2 is required to permit the affected components listed in Table 1 of Attachment to Relief Request 2 (RR 2) previously repaired by either the "half-nozzle" or the "sleeve" technique, and the remnant of the flaws to remain in service for the fourth 10-year inservice inspection (ISI) interval.

RAI-2

The NRC staff notes that in the "sleeve" repairs performed in 1989, the licensee used Alloy 82/182 weld pad and fillet weld instead of Alloy 52/152 to attach the Alloy 690 small diameter replacement nozzle to the outside surface of the hot leg piping or the pressurizer.

(a) Discuss whether there exists any plant-specific or industry operating experience regarding any active degradation of the new Alloy 82/182 weld pad and fillet weld in this particular type of the "sleeve" repair that may result in a breach of the pressure boundary.

(b) Discuss the nondestructive examinations that have been performed since repair in 1989 and the results of those examinations.

FPL Response to RAI 2(a)

Table 1 of Relief Request 2 (RR2) has been updated to reflect the latest repair configuration.

The "sleeve' repairs performed in 1989 with alloy 600 nozzles and alloy 82/182 pad welds were subsequently replaced with alloy 690 nozzles and alloy 52/152 attachment welds to the existing

L-2015-063 Attachment Page 2 of 10 82/182 pads. The 1989 date is retained in the table as a starting point for the fatigue and corrosion assessment. Current "sleeve" repairs consist of Alloy 690 nozzles attached to an exterior surface of a component or to weld pads as summarized in Table 1 of RR2 as shown below. One (1) Pressurizer nozzle and five (5) RCS Hot Leg nozzles used Alloy 52/152 partial penetration and reinforcing welds to attach the Alloy 690 nozzles to pre-existing Alloy 82/182 pads.

There is no specific OE for St. Lucie for the "sleeve" repair configurations summarized in Table 1 of RR2. FPL is aware of one (1) industry OE regarding the degradation of an Alloy 82/182 weld pad welded with Alloy 82/182 weld material in a "sleeve" repair that occurred in 2011. FPL does not have this exact configuration, however, as noted on Table 1 RR 2 and discussed in the paragraph above, there are six (6) locations welded to pre-existing Alloy82/182 pads using Alloy 52/152 weld material. Examinations to address this OE are identified in the response to RAI 2(b).

Following is the updated Table 1 of RR2 that reflects the latest and current repair configuration.

The letters in parenthesis (i.e. (A) through (B)) refer to the replacement/repair nozzle configuration illustrated in Figure 1 of RR2.

TABLE I PSL-2 Alloy 600 Small Bore Nozzles Repair Status Location Tag ID Repair Repair Method Reason for Flaw Date (Figure 1 Design) Repair Left PZR Stm Space A 1994 1/2 Nozzle Repair (1) Linear Yes Upper Head (B) Indications PZR Stm Space B 1994 1/2 Nozzle Repair (1) Linear Yes Upper Head (B) Indications PZR Stm Space C 1994 1/2 Nozzle Repair(') Leakage/ Linear Yes Upper Head (B) Indications PZR Stm Space D 1994 1/2 Nozzle Repair Preventative No Upper Head (B)

PZR Wtr Space RC-105 1989/ Sleeve Repair (2)(3) Preventative No Lower Head 1995 (C)

PZR Wtr Space RC-130 1995 Sleeve Repair Preventative No Lower Head (C)

PZR Wtr Space TE-1101 1995 Sleeve Repair Preventative No Side Shell (C)

RCS Hot Leg TE-11112HA 1989/ Sleeve Repair (2) (3) Preventative No RTD Nozzle 2003 (C)

RCS Hot Leg TE-111lX 1989/ Sleeve Repair (2) (3) Preventative No RTD Nozzle 2003 (C) I

L-2015-063 Attachment Page 3 of 10 TABLE 1 PSL-2 Alloy 600 Small Bore Nozzles Repair Status Repair Repair Method Reason for Flaw Location Tag ID Date (Figure 1 Design) Repair Left RCS Hot Leg TE-1122HC 1989/ Sleeve Repair (2)(3) Preventative No RTD Nozzle 2003 (C)

RCS Hot Leg TE-1122HD 1989/ Sleeve Repair (2)(3) Preventative No RTD Nozzle 2003 (C)

RCS Hot Leg TE-1121X 1989/ Sleeve Repair (2)(3) Preventative No RTD Nozzle 2003 (C)

RCS Hot Leg TE-1112HB 2003 1/2 Nozzle Repair Preventative No RTD Nozzle (A)

RCS Hot Leg TE-1112HC 2003 1/2 Nozzle Repair Preventative No RTD Nozzle (A)

RCS Hot Leg TE-1112HD 2003 1/2 Nozzle Repair Preventative No RTD Nozzle (A)

RCS Hot Leg TE-1122HA 2003 1/2 Nozzle Repair Preventative No RTD Nozzle (A)

RCS Hot Leg TE-1122HB 2003 1/2 Nozzle Repair Preventative No RTD Nozzle (A)

RCS Hot Leg PDT-1121B 1995 Sleeve Repair Leakage Yes Flow Nozzle (D)

RCS Hot Leg PDT-1111A 1995 Sleeve Repair Preventative No Flow Nozzle (D)

RCS Hot Leg PDT-1111B 1995 Sleeve Repair Preventative No Flow Nozzle (D)

RCS Hot Leg PDT-1111C 1995 Sleeve Repair Preventative No Flow Nozzle (D)

RCS Hot Leg PDT-1111D 1995 Sleeve Repair Preventative No Flow Nozzle (D)

RCS Hot Leg PDT-1121A 1995 Sleeve Repair Preventative No Flow Nozzle (D)

RCS Hot Leg PDT-1121C 1995 Sleeve Repair Preventative No Flow Nozzle (D)

RCS Hot Leg PDT-1121D 1995 Sleeve Repair Preventative No Flow Nozzle (D)

RCS Hot Leg Sample Line 1995 Sleeve Repair Preventative No Flow Nozzle I (D) I

L-2015-063 Attachment Page 4 of 10 TABLE I PSL-2 Alloy 600 Small Bore Nozzles Repair Status Flaw Location Tag ID Repair Date Repair 1Method (Figure Design) Repairfor Reason Left PZR Heater 3 2011 1/2 Nozzle Repair (1) Preventative No Sleeves (B) 1 (1)Alloy 690 nozzle welded to an Alloy 52/152 weld pad.

(2) Alloy 690 nozzle welded with Alloy 52/152 to existing Alloy 82/182 weld pad.

(3) Previously preventively repaired with Alloy 600 nozzle.

FPL Response to RAI 2(b)

The Pressurizer and RCS Hot Leg nozzles repaired using the "sleeve" technique with Alloy 81/182 weld pads described in RAI 2(a) receive a bare metal visual (BMV) examination each refueling outage as per the site's RCS leak test procedures and Code Case N-722. No indication of degradation has been detected to date.

RAI-3

The NRC staff notes that in paragraphA, Section 5 of Attachment to RR 2, the licensee stated, in part,that, An assessment of operating data for PSL-2 from 1/1/1995 through 2/28/2014 shows a time split of 90.5 percent at operating conditions, 2.0 percent at intermediate temperature startup conditions, and 7.5 percent of plant time at low temperature outage conditions.

In anotherparagraph,the licensee stated, in part, that, There is no need to track plant operating conditions during the remainder of the current inspection interval, as there is sufficient wall thickness in the more limiting hot leg piping to maintain the limiting allowable diameteruntil this reassessmentis made.

The NRC staff also notes that in the January 4, 2006, letter (Accession Number ML060090296),

on pages 5 and 6 of Attachment to reliefrequest 5, the licensee stated in one paragraph,in part, FPL Response.: The overall general corrosion rate was determined using the calculation methods in the TR and St. Lucie Unit 2 generation data from 1/1/95 to 12/31/04. The percentage of total plant time spent at each of the temperature conditions follows.:

High temperatureconditions 93.5%

L-2015-063 Attachment Page 5 of 10 Intermediate temperatureconditions 1.5%

Low temperatureconditions 5%"

In anotherparagraphin the January 4, 2006, letter, the licensee stated, in part, The plant operating conditions will be reassessed for the resubmittal of this relief request at the start of the next inspection interval, which begins in August 2013.

There is no need to track plant operating conditions during the remainder of the current inspection interval as there is sufficient wall thickness in the more limiting hot leg piping to maintain the limiting allowable diameter until this reassessmentis made.

(a) If the licensee had not tracked the plant operating conditions from 12/31/04 to 2/28/2014, clarify how the percentages for different modes of operation from 1/1/1995 through 2/28/2014 were obtained.

(b) It is the staff's belief that continued tracking of operating conditions will continue to be necessary for future relief requests on this subject. Alternatively, the staff believes that the licensee may have intended to state that there is no need to evaluate the effects of operating condition on corrosion rate for the remainder of this inspection interval because even if the plant remained in a shutdown condition, where corrosion is worst, for the remainderof the interval, the amount of corrosion would be within analyzed limits.

Please comment on the staff's interpretation of the above statement and whether operating conditions for the plant will continue to be tracked.

FPL Response to RAI 3(a)

The plant operating parameters and conditions are continuously collected or tracked.

FPL Response to RAI 3(b)

The intent is to state that the corrosion rate does not need to be reassessed if the plant remained in shutdown for the remainder of the inspection interval because the amount of corrosion is within the limiting allowable diameter data summarized in Tables 2A and 2B of Relief Request 2. Therefore, the sentence in the paragraph in questions, "There is no need to track plant operating conditions during the remainder of the current inspection interval, as there is sufficient wall thickness in the more limiting hot leg piping to maintain the limiting allowable diameter until this reassessment is made."

is reworded to read as follows:

"There is no need to reassess the effects of operating condition on corrosion rate for the remainder of this inspection interval because even if the plant remained in a shutdown condition, when corrosion is worst, the amount of corrosion during the remainder of the interval in the more limiting hot leg piping would be within analyzed limits until this reassessment is made.

L-2015-063 Attachment Page 6 of 10

RAI-4

The NRC staff notes that in Section B of Attachment to RR 2, the licensee did not discuss whether the plant-specific Charpy upper shelf energy (USE) data for the hot leg piping satisfies a USE value of at least 70 foot-pounds (ft-lb) to bound the USE value used in the analysis.

Provide a discussion to demonstrate that the plant-specific hot leg piping will maintain a Charpy USE data of at least 70 ft-lb. If not, provide justification.

FPL Response to RAI-4 The hot leg piping is made from SA-516 Gr. 70 carbon steel (Heat No. A-3830-62 and B-9090-63), supplied by Lukens Steel Company. The hot leg piping certified material test reports (CMTR) provide Charpy impact data for sets of three (3) transverse impact specimens per temperature to meet the ASME Section III Code piping requirements. A literature search on Charpy impact data and/or USE data for SA-516 Gr. 70 carbon steel was performed and three (3) relevant references were found. [1, 2, 3] References 1 and 2 are of interest because the author is from Lukens Steel Co. and the references were published within the same decade (1970's) the SA-516 Gr. 70 carbon steel used for the hot leg piping was produced. Reference 3 provides full Charpy data curves for SA-516 Gr. 70 in Figures C.3 (page 89) and C.4 (page 90).

The SA-516 Gr. 70 carbon steel used to fabricate the hot leg piping (Heat No. A-3830-62 and B-9090-63) was manufactured using the fine-grain steelmaking practice and normalized as per the material specification of the ASME Boiler and Pressure Vessel Code in use in the 1970's. In Reference 1, Table 2(a) lists an USE of 87 ft-lb for a transverse impact specimen (TL) taken from the 1/4 t location (QL) of a thick section SA-516 Gr. 70 carbon steel plate manufactured by conventional techniques and normalized (CON-3). From the Charpy V-notch (CVN) data curve in Figure C.4 from Reference 3 (page 90), the USE for SA-516 Gr. 70 is approximately 92 ft-lb.

The CVN USE from References 1 and 3 are similar, and fall within the large grouping of CVN USE > 80 ft-lb shown in Figure 5 of Reference 2. Although the SA-516 Gr 70 carbon steel CVN USE data in Figure 5 of Reference 2 was obtained from impact specimens of different orientation, including the non-code through thickness orientation (SL), the majority of the data is above 80 ft-lb as shown in Figure 1.

The hot leg piping SA-516 Gr. 70 carbon steel (Heat No. A-3830-62 and B-9090-63) Charpy impact data was graphically compared to the SA-516 CVN data curve in Figure C.4 of Reference 3 (page 90) (Figure 2). As observed in Figure 2, the hot leg piping impact data falls within the transition region of the SA-516 CVN data curve in Figure C.4 of Reference 3 (page 90). From the hot leg piping CMTR, the average absorbed energy at 50% shear is 53 ft-lb at a testing temperature of 90°F for the A Hot Leg and 54 ft-lb 6t 120OF for the B Hot Leg. As the testing temperature is increased, it is expected for the hot leg impact data (i.e. absorbed energy and percent shear data) to increase, following the trend of the curve in Figure C.4 of Reference 3 (page 90) shown in Figure 2.

Therefore, it is reasonable to expect that the SA-516 Gr. 70 carbon steel used for the hot leg piping (Heat No. A-3830-62 and B-9090-63) will achieve at least an USE of 70 ft-lb based on the following:

L-2015-063 Attachment Page 7 of 10

• The CVN USE data from the relevant literature is larger than 80 ft-lb for SA-516 Gr. 70 carbon steel plate from similar steelmaking techniques and heat treated to the normalized condition.

• The hot let piping impact data aligns and follows the trend of the CVN impact data curve from the relevant literature.

J

.2000 1000 0 40 80 120 160 200 240 CVN USE , ft-lbs Figure 1. Reprint of Figure 5 from Reference 2 shows that the majority of the SA-516 Gr.

70 CVN USE data is above 80 ft-lb.

L-2015-063 Attachment Page 8 of 10 Charpy Impact Data

. . I . . I . . . I. . . I . . . I . . . I . . . I . .

100 90 4 80 4

,,,I..

70- / Impact data

./ at 50% shear La 60 (~; .(j1: SA Hot Leg CL B Hot Leg

/. ---.Reference 3 (1)

E 50 I --

• 40 U M

30

.'U 0 25 50 75 100 1225 150 175 200 Temperature, OF (1) Graph digitizing software was used to obtain data points from Figure C.4 of Reference 3 (page 90).

Figure 2. Charpy impact test data for SA-516 Gr. 70.

The Summary Charpy Impact Data from Relief Request 2 (RR2) has been updated to include the Charpy impact data for the A and B Hot Legs. The data is the average of the impact test data included in the CMTRs.

L-2015-063 Attachment Page 9 of 10 TABLE 3

SUMMARY

OF CHARPY IMPACT DATA Name Heat No. Testing *Absorbed *% *USE Temperature Energy Shear ft-lb OF ft-lb SA-533 Gr. B Cl. 1 Alloy Steel Reactor Vessel A8490-2 +60 44 23 105 Plate Reactor Vessel B3416-2 +60 37 20 113 Plate Reactor Vessel A8490-1 +60 58 28 115 Plate Reactor Vessel B8307-2 +60 49 22 93 Plate Reactor Vessel A3131-1 +60 47 22 107 Plate Reactor Vessel A3131-2 +60 52 23 105 Plate Pressurizer C4754-3 +70 69 60 Bottom Head Pressurizer Upper B8618-2 +70 69 60 Head Pressurizer Lower NR 60 466-2 +20 72 35 Shell Pressurizer Lower NR 61 734-1 +30 54 25 Shell SA-516 Gr. 70 Carbon Steel A Hot Leg Piping A-3830-62 +60 48 40

+90 53 50 B Hot Leg Piping B-9090-63 +60 34 30

+120 54 50

• Average of three tests reported in the material certification.

L-2015-063 Attachment Page 10 of 10 References

1) Wilson, A. D. "The Influence of Inclusions on the Toughness and Fatigue Properties of A 516-70 Steel." J. Eng. Mater. Technol. 101.3 (1979): 265-274. [Freely available at http://www.arcelormittalna.com/Platelnformation/documents/en/iniandflats/TechnicalPaperSt udy/INFLUENCE%200F%201NCLUSIONS%200N%20THE%20TOUGHNESS%20AND%2 OFATIGUE%20PROPERTIES%200F%20A516-70%20STEEL. pdf]

2) Wilson, A. D. "Comparison of Dynamic Tear and Charpy-V-Notch Impact Properties of Plate Steels." Journal of Engineering Materials and Technology 100.2 (1978): 204-211. [Freely available at http://www.arcelormittalna.com/plateinformation/documents/en/Inlandflats/TechnicalPaperSt udy/COMPARISON OF DYNAMIC TEAR AND CHARPY-V-NOTCH IMPACT PROPERTIES.pdfl

3) Rodriguez, Edward A., and Thomas A. Duffey. "Fracture-safe and fatigue design criteria for detonation-induced pressure loading in containment vessels." Welding Research Council Bulletin 494 (2004). [Freely available at http://www.qnnallc.com/pdfs r/FM%2002%20LA-UR-04-8692.pdf]