ML20097E659

Forwards Exam Results Pertaining to NDE of Feedwater Nozzle & Safe Spargers & Draft Feedwater Sparger Circumferential Cracking Evaluation for Brunswick Units 1 & 2

ML20097E659
Person / Time
Site:	Brunswick
Issue date:	06/08/1992
From:	Starkey R CAROLINA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20097E661	List: ML20097E659 ML20097E687
References
NLS-92-134, NUDOCS 9206120279
Download: ML20097E659 (6)

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C64L Carolina Power & Light Company P.o [bx 1551

• Raleigh, N C. 27t02 l

l R 8 STARKEY.JR Vee President Nuclear Sofvtces Depaiment United States Nuclear Regulatory Commission l ATTENTION: Document Control Desk Washington, DC 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NO. 2 DOCKET NO. 50-324/ LICENSE NO. DPR-62 NUREG-0619 FEEDWATER NOZZLE AND SPARGER EXAMINATION RESULTS Gentlemen:

The purpose of this letter is to submi', pursuant to Nuclear Regulatory Commission NUREG-0619, subsection 4.4.3.1(2), the results of non-destructive examination of the f=adwater nozzles and spargers for the Brunswick Steam .ectric Plant, Unit 2. The results o. these ex'aminations, which were performed during the 1991 rieload 9 outage, are summarized in Enclosure 1. Enclosure 2 contains a General Electric evaluation performed for Carolina Power & Light Company of the circumferentially oriented flaws that were found in the sparger arm-to-tee circumferential welds.

As discussed in Enclosure 1, Carolina Power & Light Company plans to replace the feedwater spargers for the Brunswick Steam Electric Plant, Unit 2 during Refueling Outage Number 11 (Reload 11), currently scheduled to begin in September 1994. During the Reload 10 outage, CP&L intends to re-examine the feedwater spargers using an underwater high resolution remote operated camera. Due to the high dose rates in the deflooded reactor pressure vessel, CP&L does not intend to perform a liquid penetrant (LP) or ultrasonic (UT) examination of the feedwater spargers during the Reload 10 outage. Previous NRC correspondence (Reference 2 of Enclesure 1) has indicated

, that CP&L should continue to monitor the feedwater sparger crack growth at future outages by LP examination. Your concurrence with our proposed plan for using a remote camera examination, in l

lieu of liquid penetrant examination, for Cycle 11 operation with the existing feedwater spargers, is requested by September 1,1992.

Please refer any questions regarding this submittal to Mr. W. R. Murray at (919) 546-4661.

Yours very truly, 61 R. B. Starkey, Jr.

WRM/wrm (b2r90619.wpf)

Enclosures cc: Mr. S. D. Ebneter

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Mr. R. H. Lo Mr. R. L. Prevatte ff l

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, o ENCLOSURE 1 BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND 2 NRC DOCKET NOS. 50-325 & 50-324 OPERATING LICENSE NOS DPR 71 & DPR 62 NUREG 0619 FEEDWATER NOZZLE AND SPARGER EXAMINATION RESULTS s

The following information is provided in accordara e with NRC NUREG-0619, "BWR Feedwater Nozzle and Control Rod Drive Return Line Nozzle Cracking," and pertains to the nondestructive examination (NDE) of feedwater nozzles and safe ends performed at the Brunswick Steam Electric Plant, Unit 2 during the Fall 1991 refueling outage, s 1. STARTUP/ SHUTDOWN CYCLES EXPERIENCED:

When the Brunswick Steam Electric Plant, Unit 2 was shutdown in September 1991 for maintenance and Refueling Outage Number 9,158 startup/ shutdown cycles had been experienced. This quantity included three (3) startup/ shutdown cycles since the previous inspection.

11. SCOPE OF EXAMINATIONS AND SEQUENCE:

The total scope of the liquid penetrant (LP) examination was 55 sparger flow holes, twelve circumferentia! sparger tee welds (4 branch connections and 8 run connections),

and 4 nozzle blend radius regions.

The four nozzle blend radius regions were ultrasonically (UT) examined along with five (5)'

sparger arm to-tee circumferential welds.

The feodwater nozzle blend radius regions were first ultrasonically examined from the outside of the nozzle. Following draining of the reactor vessel, the inner surfaces of the nozzle blend radius regions were I. quid penetrant examined. The feedwater spargers were first visually examined (VT-3), looking for gross defects or missing pieces prior to liquid penetrant examination of fifty-five flow holes and the twelve circumferential welds associated with the feedwater spargers, (i.e., eight welds connecting the tee-to sparger -

arms and the four welds connecting the thermal sleeve to the tee), Based upon the feedwater sparger LP examination results, five (5) of the sparger arm-to-tee.

circumferential we'ds which exhibited circumferentially oriented indications were UT examined to determine the extent of the cracking.

Ill. DESCRIPTION OF EXAMINATION TECHNIQUES:

The non-destructive examination (NDE) methods employed for the external exammation of the feedwater nozzle blend radius regions was manual ultrasonic examination. The ultrasonic examinations were performed from the nozzle outside diameter using special contoured transducer wedges designed specifically for tone 1,2, and 3, at the Brunswick Steam Electric Plant (see attached excerpt from the General Electric Company procedure GER UT 303). The ultrasonic examination employed angle beam shear wave techniques as recommended by General Electric Company. The inner surface of the nozzle blend radius regions was liquid penetrant examined along with the sparger flow holes and circumferential welds. As previously discussed, a video was made of the results of the LP examination and a review of this video determined that five of the circumferential welds should be ultrasonically examined. The selected feedwater sparger El-1

circumferential welds were manually ultrasonicalh: examined using 45* angle shear wave transducers to determine the length of the outtle diameter indications.

IV. NONDESTRUCTIVE EXAMINATIONS RESULTS:

No relevant indications were found on the nozzle blend radius rewions using ultrasonic and liquid penetrant examinations.

The feedwater sparger flow holes continue to show slow crack growth. No significant new flow hole crack growth was found, and no pieces of the spargers have separated from around the flow holes. No relevant LP indications were found on the outside diameter surface of the circumferential welds connecting the tee to the thermal sin ie.

Five of the eight spargst arm-to-tee circumferential welds had circumferentie.Ily oriented ,

liquid penetrant indications on the outside diameter surface, the longest of which was two inches long on the right side of the 135" azimuth sparger tee. It was assumed that these outside diameter LP indications represented through wall cracks; therefore these five welds were subsequently ultrasonically examined for the full 3G0" circumference to determine the length of the indications on the inside diameter surface. Due to the weld contuur and close proximity to the flow holes, only two of the cracks could have the inside (ameter length sized; however, it was verified that no crack on any sparger examined extends beyond the liquid penetrant indications on the outside surface. The longest crack found on the inside diameter surface was 1.875 inches on the right side of the 135* azimuth tee. The conclusion of the liquid penetrant and ultrasonic examinations is that all of the circumferentially oriented cracks are through wall, the cracks appear to have initiated from adjacent flow hole cracks, and the cracks now appear to be following the heat affected zone of the sparger tee-to-arm circumferential welds. All of the circumferential cracks are on the side of the sparger arm where the flow holes are located and are growing downward. Although new circumferentially oriented flaws were found, the circumferential indication on the outside diameter of the right side of the 135* tee was noted during the last examination, and no significant change was observed uuring the operating cycle (Cycle 9) following Reload Number 8.

V. SYSTEM MODIFICATIONS AFFECTING FEEDWATER FLOW AND/OR TEMPERATURE:

There have been no system modifications performed since the last refuel outage which would affect the feedwater flow or temperature.

VI. ON-LINE LEAKAGE MONITORING:

No on-line leakage monitoring system for the detection of feedwater bypass leakage past the thermal sleeve connections has been installed for the Brunswick Plant, Unit 2.

Vll. SAFETY EVALUATION

SUMMARY

The feedwater spargers are not safety related equipment. Failure of a circumferential weld would not affect the safe shutdown capability of the Brunswick Steam Electric Plant, Unit 2. Enclosure 2 determined the critical flaw size for joint failute (13.57 inche.

and the maximum permissible length of a "beginning of fuel cycle flaw" to be 10.9 bches. The longest documented existing circumferentially orierited flaw is 2 inches long on the right side of the 135 azimuth sparger tee. Therefore, Carolina Power and Light Company believes that the continued operation of the Brunswick Plant, Unit 2 until E1-2

the next refueling outage, currently scheduled to begin March 1993, is ,i ..nd will not adversely affect the health and safety of the public. The evaluation . sing the flow hole cracking ud smallloose parts, General Electric Company Evaluation No RDE 421289, Rev.1, 'BSEP Unit ll Feedwater Sparger Crack Growth Assessment,"

Feb.1990, previously Mnsmitted to the NRC as part of Reference 1 la still valid.

Vill. FUTURE PLANS FOR THE DNP UNIT 2 FEEDWATER SPARGERS.

Carolina Power & Light Company plans to replace the nedwater spargers for the Brunswick Steam Electric Plant, Unit 2 during the Refuelmo Outage Number 11 (la sad 11), currently scheduled to begin in September 1994.

Previous correspondence (Referenct 2) with the NRC has resulted in the directive that CP&L should continue to tenitor the sparger crack growth at future outages by ligold penetrant examination. The performance of ultrasonic or liquid penetrant testing requires that the reactor vessel be dsflooded.

Due to the high dose rates in the deflooded reactor pressuro vessel (approximately 1 millirem per second, with the shlended work platform in position), CP&L does not intend to perform a liquid penetrant or ultrasonic examination during Refueling Outage Number 10. Instead, CP&L proposes to re examine the feedwater spargers using an

, underwater, h!gh resolution, remote operated camera. The remote camera examination is I expect)d to save approximately 9 person rem.

The Company believes that the extensive non-destructive examination performed during h the Reload 9 outage provides a solid data base on the feedwater spargers that will allow use of a camera examination during Refueling Outage Number 10. The examination s inspection data obtained during Refueling Outage Number 9 will be used to determine those areas on which to concentrate the comers inspection. Thus, a thorough -

examination (and subsequent repairs, if required) can be performed w;thout deflooding the reactor pressure vessel.

If any sparger ploces appear liksly to become loose parts prior to replacement of the sparger during the Reload 11 outage, a contingency repair will be implemented. This contingency repair may consist of using divers to remove the piece (s) or to capture the potential loose piece (s) in place using underwater welding.

Based on the information desci. bed above, Carolina Power & Light Company requests that the NRC Staff provide concurrence with the Company's proposed plan for using a remote camera examination, in lieu of liquid penetrant examination, for the final cycle of operaticn with the original sattgers (Cycle 11), in order to support planning activities for the Brunswick Plant, Unit 2 Noad to outage, CP&L request NRC Staff concurrence be provided by September 1,1992.

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REFERENCES:

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1. Letter from L. l. Loflin (CP&L) to Document Control Desk (USNRC) dated September 14,1900 (Serial No. NLS 901831 " Performance of Nondestructive Examination of Feedwater Norries and Safe Ends During The 1989/1990 Maintenance / Refueling Outage.'

2. Letter from Mr. N. D. Le (USNRC) to Mr. L. W. Eury (CP&L) dated June 6,1991, ' Review of the Carolina Power & Light Company's Repnrt on Performance of Nondestructive Examination of Feedwater Norries and Safe Ends During the 1989/1990 Maintenancemefueling Outage at Brunswick Steam Electric Plant, Unit 2 (TAC No. 77745).'

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