ML17046A659

Lnservice Inspection Summary Report Unit 1, Interval 5, Period 1, Outage 1, Refueling Outage Dates: 10/15/2016 to 11/20/2016, Fuel Cycle 29: 11/23/2014 to 11/20/2016

ML17046A659
Person / Time
Site:	Prairie Island
Issue date:	02/15/2017
From:	Northard S Northern States Power Company, Minnesota, Xcel Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L -PI-17 -009
Download: ML17046A659 (11)

Text

1717 Wakonade Drive Welch, MN 55089 Xcel Energy@

800.895.4999 R E S P 0 N SIBLE BY NAT U R E xcelenergy.com L-PI-17 -009 10 CFR 50.55a FEC \ 5 2017 U S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Prairie Island Nuclear Generating Plant Unit 1 Docket 50-282 Renewed License No. DPR-42 lnservice Inspection Summary Report Unit 1. Interval 5. Period 1, Outage 1. Refueling Outage Dates: 10/15/2016 to 11/20/2016, Fuel Cycle 29: 11/23/2014 to 11/20/2016 During the 2016 Prairie Island Nuclear Generating Plant (PINGP) Unit 1 refueling outage, an inservice inspection (lSI) examination for the first period of the fifth interval was conducted. Form OAR-1 Owner's Activity Report (Enclosure 1) is being submitted for this time period as required by the American Society of Mechanical Engineers (ASME) Code Section XI, in accordance with the provisions of Code Case N-532-5, and is intended to satisfy the inspection reporting requirements.

The form includes a listing of items with flaws or relevant conditions that required evaluation for continued service (Table 1) and an abstract of repair/replacement activities required for continued service (Table 2).

Also attached is an evaluation of the acceptability of inaccessible areas of the Unit 1 Containment Vessel (Enclosure 2) in accordance with the requirements of 10CFR 50.55a(b )(2)(ix)(A).

Summary of Commitments This letter contains no new commitments and no revisions to existing commitments.

~~. .

Scott Northard Site Vice President, Prairie Island Nuclear Generating Plant Northern States Power Company - Minnesota Enclosure (2) cc: Administrator, Region Ill, USNRC Project Manager, Prairie Island, USNRC Resident Inspector, Prairie Island, SNRC

ENCLOSURE 1 FORM OAR-1 OWNER'S ACTIVITY REPORT for Unit 1, Interval 5, Period 1, Outage 1, Refueling Outage Dates: 10/15/2016 to 11/20/2016, Fuel Cycle 29: 11/23/2014 to 11/20/2016 3 pages follow

FORM OAR-1 OWNER'S ACTIVITY REPORT Prairie Island Nuclear Generating Plant As required by the provisions of ASME Code Case N-532-5 Report Number 1R30 Plant Prairie Island Nuclear Generating Plant, 1717 Wakonade Drive East. Welch, Minnesota, 55089 Unit No. _ __,1_ __ Commercial service date -----'1'""2"-/1_,_,6'-'-/1.!..:9"-'7_,3,___ __ Refueling outage no. -----'1'-'-R-'-"3""0'---

Current inspection interval_51h lSI Inspection Interval for class 1 2, and 3. 2nd IWE Inspection Interval for class MC I

Current inspection period_ 1st lSI Inspection Period for class 1, 2, and 3. 3rct IWE Inspection period for class MC Edition and Addenda of Section XI applicable to the inspection plans 2007 Edition - 2008 Addenda for class 1, 2.

and 3. 2001 Edition - 2003 Addenda for class MC _ __

Date and revision of inspection plans _ __,6'-'-'/2"'"'2"'-/-'-'16"--'-'R,_,e"'"v.~1_,__,_,fo'-'-r~c'""la,s"'"s_,_1_,__,=.2.._,a"'n-'-"d'-'3""'._1.,_,0~/2""6"'"/-"12=--.c.R,e,_,_v'-'.9"'--'-'fo"-'-r__,c""la.,s""s-"M'""C"'----

Edition and Addenda of Section XI applicable to repair/replacement activities, if different than the inspection plans Same as Inspection Plan for class 1.2. and 3. 2007 Edition - 2008 Addenda for class MC Code Cases used for inspection and evaluation; _ __,_N_,__-""'5,32,_-_,5. __,'--'N_,-6,_,6'--'1__,-2=-<,_,_N_,__-_,__7-'-'16"---'-1.._,N'-!-!-7_,_7-"6"--,!..!N'-'-7~2~2,_-1_,___ _

CERTIFICATE OF CONFORMANCE I certify that (a) the statements made in this Owner's Activity Report are correct; (b) the examinations and tests meet the Inspection Plan as required by the ASME Code, Section XI: and (c) the repair/replacement activities and evaluations supporting the completion of refueling outage number 1R30 conform to the requirements of Section XI.

Date I *~ 2.4. - 'ZO I ~{

CERTIFICATE OF INSERVICE INSPECTION I, the undersigned, holding a valid commission issued by the National Board of Boiler and Pressure Vessel Inspectors and employed by The Hartford Steam Boiler Inspection and Insurance Company of Connecticut have inspected the items described in this Owner's Activity Report, and state that, to the best of my knowledge and belief, the Owner has performed all activities represented by this report in accordance with the requirements of Section XI.

By signing this certificate neither the Inspector nor his employer makes any warranty, expressed or implied, concerning the repair/replacement activities and evaluation described in this report. Furthermore, neither the Inspector nor his employer shall be liable in any manner for any personal injury or property damage or a loss of any kind arising from or connected with this inspection.

Date(_j~ {) 2, 2.011

TABLE 1 ITEMS WITH FLAWS OR RELEVANT CONDITIONS THAT REQUIRED ...

EVALUATION FOR CONTINUED SERVICE Examination Category and lteni Description ' Evaluation Description Item Number B-L-2, B12.20 12 RCP Pump *Internals Two indications of minor gouges determined to be non-relevant AR 1539956.

B-P, B15.80 Reactor Vessel Bottom Head per Non-relevant indications of light translucent Code Case N-722-1 streaks AR 1541635.

B-P, B15.10 SP 1168.1 RCS Pressure Test Non-relevant p1;1cking and fitting indications ARs: 1542388, 1542377.

B-P, B15.10. SP 1392 Bolted Connections Borated Dry White boric acid indications at bolted conn.

C-H, 07.10 ~ystems Pressure Test accepted by evaluation AR 1538861.

C-H, 07.10 SP 1168.12 Sl Accumulator Pressure Non-relevant packing indication AR 1542409.

test .

C-H, 07.10 SP 1168.13 Safety Injection Pressure Non-relevant packing and fitting indications test ARs: 1540887, 1540890, 1540893, 1540891.

C-H, 07.10 .SP 1168.13 Safety Injection Pressure Dry white boric acid indication at bolted conn.

test accepted by evaluation AR 1541116.

C-H, 07.10 SP 1168.14 Containment Spray Dry white boric acid indication at packing. Non-Pressure Test releva11t packing indication AR 1514520.

C-H, 07.10 SP 1168.16 CVCS Pressure Test Non-relevant packinQ indication AR 1447393.

C-H, 07.10 SP 1168.17 Feedwater Pressure Test Non-relevant indication outside code boundary AR 1542651.

C-H, 07.10 SP 1168.6 Aux Feed Pressure test Non-relevant packing indication AR 1542522.

D-B, D2.10 D-B, D2.10 SP 1168.4 Component Cooling Non-relevant bolted connection and fitting Pressure Test indications AR 1538737..

• D-8, 02.10 SP 1168.8 Cooling Water Pressure Non-relevant mechanical connection Test indications AR 1518348.

E*A, E1.11 Containment Accessible Areas 3 indications of gouges accepted by evaluation AR 1540848.

E-A, E1.30 Moisture Barrier 3 indications of la13k of adhesion and 1 tear accepted by corrective measures AR 1541212 and WO 478898.

F-A, F1.10b Rupture Restraint 9-RHR-3A Residual Heat Removal Restraint with indication oflack otthreact engagement.

Accepted by evaluation EO 27137 and AR 1539806. .

F-A, F1.20a Rod/Clamp 1-SIRH-15 Safety Injection hanger with indication of misalignment. Accepted by evaluation EC 27737 and AR 1539778.

F-A, F1.20a Rod/Clamp 1-RSH-3 Safety Injection small bore support rod has slight bend non-relevant EC 27737 and AR 1538986.

F-A, F1.20b Constant Support 1-MSDH-24 Main Steam large bore support missing scale and rod in contact With condu.it non-relevant EC 27737 and AR 1538356.

F-A1 FL30a Rod/Clamp 1-CWH~188 Cooling Water hanger with indication of bent rod at top of hanger top.

Accepted by evaluation EC 27137 and AR

• - 1539147.

F-A, F1.30b Pipe Rack Support 1-CWH-261 Cooling Water multiple support assernbly with indications cif bolt not fully engaged and bent column. Accepted by evaluation EC 27737 and AR 1539153.

F-A, F1.30c Spring Hanger 1-CWH-218 Cooling Water hanger with indication of skewed anchor bolt in baseplate.

Accepted by evaluation EC 27737 and AR 1539844.

F-A, F1.40 12 RCP Support Column H-2 Hairline crack in grout. Non-relevant indication outside the scope of ASME XI AR 1540224.

TABLE2 ABSTRACT OF REPAIR/REPLACEMENT ACTIVITIES REQUIRED FOR CONTINUED SERVICE Code Plant ID Item Description of Work Completed Date RIR Class # Description Completed Plan#

D2 DSLGEN 035-072 Lube Oil Cooler Performed weld build of eroded areas of 3 D2 DSL GEN 3/13/2015 1-29-002 the channel ends and covers as needed to 035-062 Jacket Water restore sealing surfaces.

Cooler D2DSL GEN 035-052 Air Cooler Cooling 3 3-CL-88 Water Pipe Replaced segment of pipe due to MIC. 3/9/2016 1-29-003 Segment Replaced the containment fan coil unit 2 174-011 11 FCU Coils 1/4/2017 1-29-026 coils.

Cooling Replaced a section of Cooling Water pipe 3 4-CL-11 Water system 4/12/2016 1-29-012 due to MIC.

pipe spool 13 CHG PMP 2 162-393 Replaced Cap Screw on Desurger. 8/3/2016 1-29-032 Hyd Desurger Replaced the containment fan coil unit 2 174-014 14 FCU Coils 1/4/2017 1-29-034 coils.

Replaced the containment fan coil unit 2 174-012 12 FCU Coils 1/4/2017 1-29-035 coils.

Replaced the containment fan coil unit 2 174-013 13 FCU Coils 1/4/2017 1-29-036 coils.

Replaced the D2 Diesel Generator air cooler 3 035-052 D2 Air Cooler 1/3/2017 1-29-043 tube bundle.

ZX Piping Segment Installed Code Case N-661-2 weld overlay 3 10-ZX-75 12/16/2016 1-29-060 (located in on area of thinning due to MIC.

the E1 elbow)

ENCLOSURE 2 Evaluation of the Acceptability of the Inaccessible Areas of the Unit 1 Containment Vessel in Accordance with the requirements of 10CFR 50.55a(b)(2)(ix)(A) 5 pages follows

Condition Evaluation NUMBER: 01538143-03 SHEET NO: 1 OF 5 TITLE: EVALUATION OF INACCESSIBLE CONTAINMENT AREAS DATE: 10/22/2016 COMP. BY: TRD 1.0 Purpose and Summary Result The purpose of this evaluation is to evaluate the acceptability of inaccessible areas of the Unit 1 Containment vessel in accordance with the requirements of 10CFR 50.55a(b )(2)(ix)(A).

The containment vessel is determined to be acceptable for continued service with no corrective actions.

2.0 Background

AR 01538143 "identified that there was numerous excessive deposits of boric acid around the 695 elevation of containment that were due to water migration through the concrete originating from the flooded Sump B." The flooding was the result of leaking RHR suction valves which allowed water from the Refueling Water Storage Tank to leak into the containment RHR sump and overflow into the surrounding areas. Increasing sump level was identified in June of 2015 with potential exposure of the containment vessel to borated water conservatively estimated at 18 months [4.1].

Migration of borated water through the containment concrete (as identified in the AR) indicates borated water may have come in contact with the containment vessel. Borated water in contact with the containment vessel is a condition that could indicate the presence of or could result in degradation of inaccessible areas.

As required by 10CFR 50.55a(b)(2)(ix)(A):

(A) Metal containment examinations: First provision. For Class MC applications, the following apply to inaccessible areas.

(1) The applicant or licensee must evaluate the acceptability of inaccessible areas when conditions exist in accessible areas that could indicate the presence of or could result in degradation to such inaccessible areas.

(2) For each inaccessible area identified for evaluation, the applicant or licensee must provide the following in the lSI Summary Report as required by IWA-6000:

(i) A description of the type and estimated extent of degradation, and the conditions that led to the degradation; (ii) An evaluation of each area, and the result of the evaluation; and (iii) A description of necessary corrective actions.

Condition Evaluation NUMBER: 01538143-03 SHEET NO: 2 OF 5 TITLE: EVALUATION OF INACCESSIBLE CONTAINMENT AREAS DATE: 10/22/2016 COMP. BY: TRD 3.0 Evaluation 3.1 A description of the type and estimated extent of degradation, and the conditions that led to the degradation; Based on a long history of borated water exposure with no measureable degradation and evaluation of potential corrosion rates, there is a high level of confidence there is no significant degradation of the containment vessel.

Refueling cavity leakage has been experienced in various areas of containment of both units dating back to approximately 1988. The most prominent a,nd consistent leakage was through the grout in Sump B [4.2]. Cavity leakage has been mitigated in recent years after cavity liner modifications were performed in 1R27 (2011) and 2R27 (2012) [4.3].

In order to access the potential degradation to the containment vessels, the site performed several excavations of areas known and suspected of repeated or long term exposure to borated water as summarized in the below table.

Excavation When/Reference Results Location Unit 2 1998 (2R 19) [4.2] During the 1998 Unit 2 refueling outage Containment (2R19) water was found entering sump 8 RHR Sump B from the area outside the RHR suction penetration sleeve. Leakage was measured at 0.5 gph. The water was sampled and determined to be at refueling water boron concentration, approximately 2700 ppm. The water also contained short lived nuclides. The pH of the water was 7.8, slightly alkaline. The grout around the penetration was partially removed to determine the condition of the containment vessel wall. The vessel showed no signs of degradation.

Unit 1 2002 (1 R22) [4.2] Removed grout unit 1 sump 8 for visual Containment inspection of containment vessel.

RHR Sump B Unit 2 2008 (2R25) [4.2] The grout was removed from sump B to Containment allow visual and UT inspection of the RHR Sump 8 containment vessel. There was no indication of degradation. The leakage in sump 8 was reported to well up from the bottom of the removed grout at a rate of

Condition Evaluation NUMBER: 01538143-03 SHEET NO: 3 OF 5 TITLE: EVALUATION OF INACCESSIBLE CONTAINMENT AREAS DATE: 10/22/2016 COMP. BY: TRD approximately 1gph.

Unit 1 2009(1R26) Removed grout and took UT readings Containment W0372531 (BOP-UT-09-012). All readings above RHR Sump B 3.56" thickness. No degradation.

Unit 1 RV 2011 (1 R27) [4.3] Concrete was removed from sump C. VT Sump C examination of exposed rebar and containment vessel, and UT thickness readings of containment vessel showed no indication of degradation (reference VT report BOP-VT-11-032 and BOP-UT 01 0). The containment vessel showed no rust, pitting or other degradation. Ten thickness readings were taken with a lowest reading of 1.561 inch as compared to the nominal/design shell thickness of 1.5 inch.

Unit 2 RV 2012 (2R27) [4.3] Concrete was excavated from the unit 2 Sump C reactor vessel sump C in 2R27 (spring 2012) to allow for direct visual examination and UT thickness measurement of the containment vessel. Water seeped into the excavation at approximately 8 cubic inches in 15 minutes (AR01337188). The pH of the water was not tested. Boron concentration was less than 10 ppm and reactivity was 2.0 1E-05 uCi/ml Co-58. The containment vessel was found to be in good condition with no degradation. UT thickness readings were above 1.6" as compared to a design thickness of 1.5" (NDE report BOP-VT-12-055). The exposed rebar was also in good condition with no significant degradation The above summary shows six excavations performed over a period of approximately 14 years. The excavations included areas known to be periodically wetted (RHR Sumps) and areas thought to be continually wetted (RV Sumps as they are near the low point of the containment vessel).

None of the excavations showed detectable degradation either visually or with ultrasonic thickness measurement.

Condition Evaluation NUMBER: 01538143-03 SHEET NO: 4 OF 5 TITLE: EVALUATION OF INACCESSIBLE CONTAINMENT AREAS DATE: 10/22/2016 COMP. BY: TRD A Root Cause Evaluation (RCE) of refueling cavity leakage assessed potential corrosion rates of the containment vessels with the following results [4.2]:

Tests at ambient temperature indicate that the rates of corrosion of steel in aerated concentrated boric acid solutions range between 0.002 to 0.007 inches (Section 4.4.1 of the Boric Acid Corrosion Guidebook, Rev. 1 [29]).

These rates are probably conservative for the current application since the pH of solution in contact with the steel containment vessel will be buffered by alkalinity from the cement in the concrete.

A test in 1998 of leaking water at the RHR penetration in Sump B where grout had been removed indicated that the pH was 7.8 [30]. Another test in 1998 of water collected on the floor of the RCDT room indicated a pH of 7.0 [30]. The water had high concentrations of boron which, if it had not been buffered, would have resulted in pH values of 5 or less. This indicates that the boric acid had been buffered by alkalinity from the cement in the concrete. Corrosion rates in near neutral water at ambient temperatures are about 0.2 mm/year (0.008 in./year) (Figure 3 on Page 536 of [28]).

A long term test was performed by Florida Power and Light to determine the corrosion rate of carbon steel rebar in contact with concentrated boron solution (2370 ppm) at pH 7.4 at ambient temperature [31]. This test measured a corrosion rate after 8 years of test of 0.005 inches/year.

Research performed as part of the RCE indicates potential corrosion rates of approximately 0.008 in I year. A potential exposure of 18 months would not result in significant degradation of the containment vessel.

Based on six excavations over a period of 14 years with no degradation and an expected corrosion rate of approximately 0.008 in./year, there is a high level of confidence that the potential borated water exposure during Unit 1 cycle 29 did not result in any significant degradation.

3.2 An evaluation of each area, and the result of the evaluation.

All areas of potential degradation as a result of RHR Sump B flooding are discussed above.

The evaluation has determined a high level of confidence there is no significant degradation of the containment vessel.

Condition Evaluation NUMBER: 01538143-03 SHEET NO: 5 OF 5 TITLE: EVALUATION OF INACCESSIBLE CONTAINMENT AREAS DATE: 10/22/2016 COMP. BY: TRD 3.3 A description of necessary corrective actions.

As there is no indication of degradation, no corrective actions are necessary.

4.0 References 4.1 AR 01484218 Unit 1 Sump B level increasing.

4.2 RCE 01160372-01 Refueling Cavity Leakage Event Date: 1988-2008.

4.3 AR 01160372 Refueling Cavity Leakage Corrective Actions and the LRA 5.0 Attachments None.