ML19309C357

Forwards Final Technical Evaluation Rept Re Feedwater Nozzle Cracking.Insp Program for Feedwater Nozzles & Control Rod Driveline Return Line Nozzle Acceptable

ML19309C357
Person / Time
Site:	Quad Cities
Issue date:	03/28/1980
From:	Carfagno S FRANKLIN INSTITUTE
To:	Butcher E Office of Nuclear Reactor Regulation
References
CON-NRC-03-79-118, CON-NRC-3-79-118 NUDOCS 8004080494
Download: ML19309C357 (6)

Text

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aj1i J.Franklin Research Center A Division of The Franklin Institute March 28, 1980 United States Nuclear Regulatory Commission h*ashington, D.C. 20555 Attention: Mr. Edward J. Butcher, Jr.

Project Officer

Reference:

FRC Project C5257 NRC Contract NRC-03-79-ll8 NRC TAC No.~ 08554

, FRC Task 89

Title:

Quad Cities Unit 1

Dear Mr. Butcher:

Enclos2d ts the_ final Technical Evaluation Report for the above-referenced task.

Subject to NRC approval, submission of the report will close out FRC-Task 89.

Very truly yours,

/ $U ' D S. P. Carfagno Project Manager SPC/RCH/mw Enclosure cc: J. R. Fair-4 JooV:

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M 040gg The Benjamin Franklin Parkway, Philadelphia. Pa.19103 (215) 448-1000 TWX-710 6701889

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. TECHNICAL EVALUATION REPORT FEEDWATER N0ZZLE CRACKING: QUAD CITIES UNIT 1 FRC TASK NO. 89 NRC TAC NO. 08554 Prepared by: J. E. Prior Performing Organization Franklin Research Center The Parkway at Twentieth Street FRC Project No.

Philadelphia, PA' 19103 C5257 Sponsoring Agency Nuclear Regulatory Commission NRC Contract No.

Washington, D.C. 20555 NRC-03-79-118 This report was prepared as an account of work sponsored' by an agency of the United States Government. Neither the United States Government nor any agency thereof, or any of their employees, makes any warranty, expressed or implied, or assumes-any legal liability or responsibility for any third party's use, or the results of such use,~

of any information, apparatus, product or process dis-closed in this report, or represents that its use by'such third party would not infringe-privately owned rights.

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O TECHNICAL EVALUATION REPORT

- UNIT: QUAD CITIES N0. 1 . LICENSEE: COMMONWEALTH EDIS0N DOCKET N0. 50-254 TAC'NO. 08554

1.

SUMMARY

The planned . inspection program for the feedwater nozzles and the control rod drive (CRD) return line nozzle during the January,1979, refueling outage is acceptable. Installation of interference fit spargers during the January, -

1976, refueling outage has alleviated fatigue cracking in the Enozzles. The CRD return line was valved out during the Spring, 1977, refueling outage, effectively ending the source of the thermal cycling determined to be-the-mecha-nism of cracking.

2. INTRODUCTION j The proposed inepection program for the feedwater nozzles and the CRD re-turn line nozzle during the January, 1979, refueling outage was submitted to the NRC review. The object of the review was to ensure that the actions taken by the Licensee will be technically adequate. The program was evaluated accor-

, ding to the guidelines established in NUREG 0312. The review was confined to the issue of the pressure boundary integrity as influenced by nozzle cracking.

3. BACKGROUND Field experience has shown that fatigue cracks can be expected in feedwater nozzles and CRD return line nozzles in BWR pressure vessels. Obse rvations ,

theoretical explanations, and recommended remedial actions were ' discussed in NUREG 0312.

The principal factors responsi'le for nozzle crack initation are thermal

- cycling and the stresses from the differential thermal expansion between the weld-deposited stainless steel cladding and the forged, low-alloy steel nozzle, gg

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During the January, -1976, refueling outage, interference fit feedwater spargers were installed. A complete dye-penetrant examination of the four feedwater nozr.ies was performed prior to the installation of the new spargers.

All indicatf.ons found were removed by grinding, leaving no linear indications.

A re-examination of these nozzles was performed during the 1977 Winter refueling startup/ shutdown cycles. The examination consisted of an external ultrasonic inspection and an underwater television camera inspection. No reportable.indi-cations were found.

During the Spring, 1977, refueling outage the CRD return.line was valved out, eliminating the source of the thermal cycling responsible for the fatigue cracking.

4. TECHNICAL EVALUATION 4.1 FEEDWATER N0ZZLES 1

The following items were included in the planned inspection program:  ;

1. Examination of the visible portions of the four spargers using under-water television equipment.

. 2. Ultrasonic inspection of the inner blend radii and bores of the four nozzles.

3. Ultrasonic inspection of the four feedwater nozzle safe ends and safe-end welds.

4. If a relevant indication is evaluated as 80 percent full screen height or more at calibration sensitivity, a dye-penetrant exami-nation will Se made of the area containing. the indication.

FRC considers the plan for the inspection of the feedwater nozzles to.be acceptable with the following comments:

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1. For -reactors where the feedwater nozzles were examine'd previously by dye-penetrant test and all detected. cracks removed, NUREG 0312' requires subsequent penetrant test examination of the nozzles. '

This is -to be performed at the earlier of either (1) every other refueling outage, or (2) the scheduled refueling outage after 20,.

but prior to 40, startup/ shutdown cycles af ter the last penetrant .

test examination. Although the planned inspection. program does

- no t mee t the above requirement of NUREG 0312, it is recognized

'that the installation of interference fit thermal sleeves has been shown to be effective in alleviating cracking in feedwater nozzles. .

In addition, an inspection during the 1977 Winter refueling outage 1 was conducted' using_ external ultrasonic testing and' an underwater

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television camera. No reportable indications were found at that time. Therefore, significant crack growth. should not occur before the Fall, 1980, refueling outage.

2. The planned installation of new thermal sleeves and the removal of the stainless steel cladding must be accomplished during the 1980 outage. At this time a thorough penetrant test examination of the nozzles should be conducted before and af ter clad removal.

Inspection before clad removal will provide useful background information concerning the degree of cracking in the nozzle.

4.2 CONTROL ROD DRIVE RETURN LINE N0ZZLE The CRD return line nozzle inspection program encompasses the following:

1. Examination of the visible portion of the thermal sleeve using; underwater television equipment.

2. Ultrasonic examination of the inner blend ' radius.

3. Ultrasonic examination of the vessel wall below the nozzle, extending 8 inches below the centerline of the nozzle when physi-cally practical.

4. Ultrasonic examination of the safe ends and safe-end welds.

Following the 1977 nozzle inspection, the CRD return line was valved out, terminating the cold condensate flow through the return line. Elimina-ting this cold flow puts an end to a source of thermal cycling and should alleviate cracking. However, in at least one BWR, additional cracking in the apron region below the nozzle was observed one year af ter all detected cracks had been ground out and the line valved out. In addition, vessel wall cracks are less tolerable than nozzle cracks because the margin of excess material over the ASME code minimum is less in the shell than in the nozzle reinforcement. For this reason, examination of the apron region below the nozzle'by an appropriate technique should be performed during the 1980 outage to ensure that cracking has not occurred.

The_ valve which was valved out and the adjacent line should be examined -

by appropriate means during the 1980 outage - to ensure that stress-corrosion cracking has not occurred as a result of the stagnant. water in the line.

After review of all the factors involved, the inspection program is considered to be acceptable, contingent upon a thoroughiinspection-in 1980.

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5. CONCLUSION The NRC considers the January, 1979, inspection program for the feed-water nozzles and the CRD return line nozzle to be. acceptable. However,=

since the- 1980 outage, as planned, allows sufficient time for replacement of thermal sleeves ~and removal of cladding, the opportunity should be uti .-

lized to develop a program for a thorough inspection of the nozzles -to.

ensure that the nozzles, safe ends,-and thermal sleeves are crack free'.

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