ML17195A726
| ML17195A726 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 03/11/1985 |
| From: | Gilbert R Office of Nuclear Reactor Regulation |
| To: | Zwolinski J Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8503130312 | |
| Download: ML17195A726 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION REGION 111 799 ROOSEVELT ROAD GLEN ELLYN, ILLINOIS 60137 MAR 8 1985 MEMORANDUM FOR:
Boen-Dar Liaw, Materials Engineering Branch, NRR FROM:
J. J. Harrison, Chief, Engineering Branch, Division of Reactor Safety-, Region III
SUBJECT:
DRESDEN UNIT 2 SAFETY EVALUATION.REPORT Transmitted, herewith~ ts--the-~Reg*f'on.III input to the Dresden Unit 2
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Safety Evaluation Report.
Attachment:
As stated
. cc:. R. A. Gilbert, ORB-5 i
8503260131 850313 CF ADOCK 05000237 I CF J. J. Harrison, Chief Engineering Branch
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Inspection and Examinatfon Pacific Nuclear Systems, Inc., performed a decontamination of Dresden Unit 2 recirculation system suction and di~charge piping, ring headers,
_cross ties, and risers to the thermal sleeves. This operation was not observed by the staff.
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Lambert, MacGill and Thomas (LMT) Incqrporated and Universal Testing Laboratories (UTL) Incorporated performed ultrasonic (UT) examination for Commonwealth Edison Company at Dresden Unit 2.
UTL activities were li~ited to independently evaluating two welds by UT eKami nation in accordance with NRC Generic Letter 84-11.
During examination of the Reactor Recirculation system by LMT an indication of a.defect was reported in weld No. PDIA..;D:...14 in line No.
2~0201A-28 oriented circumferentially, 32 11 from the reference point measured clockwise. The indicatioh was reported as 7/8 11 in length. This indication was evaluated as 11 probab 1 eu-IGSCC of very sha 11 ow depth.
This indication was re-examined..by the 1icensee 1 s 1eve1 II I examiner who confirmed this to be a linear reflector of less than 7% of the pipe wall thickness. There were no other indications reported in welds scheduled for reexamination during this outage.
The inspection team from UTL re-examined weld No. PDIA-D-14 using shear wave, IP creeping wave, and longitudinal wave examination techniques and identified this indication as ID geometry. It is believed that the*indication was caused when a 11window 11 was closed during welding of the root pass. A window is a small gap cut out of the consumable insert used to fuse the root. This window allows observation of the ID surface during root fusion and may have the additional function of providing an inlet and vent for the inert gas purge.
These windows are the last areas fused to complete the root and often create
- a small ge6metric reflector.
In addition to the welds scheduled for examination for this refueling outage, the licensee developed an initial sampling plan of 84 welds to be examined in accordance with NRC Generic Letter 84-11.
Indications of IGSCC were identified in the Reactor Water Clean-Up (RWCU) system.
No indications were identified in any of the other systems examined.
Due to the indi.cations identified in the RWCU system all accessible welds in this system were examined. This increased the sample size to 102 welds.
Fifteen (15) RWCU welds were found to have crack indications; ten (10) welds were outside of the drywell and five (5) welds were inside the drywell.
Subsequently, NUTECH developed a modification and repair program for the licensee.
The modification and repair program is delineated in ECN-CEC-09-018, Revision 3 and CEC-09-016, Rev. 1, which addresses all RWCU p~~ing from MOV-2-1201 thru penetration No. X113 up to MOV-2-1201-3.
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Conclusions Based on the staffs review of procedures, equipment, the modification and repair programs, in-process welding, radiographs, documentation of replacement welds and observation of examination and repair activities, the staff has concluded the following:
The level II and III UT examiners performing examinations and evaluating indications were qualified by having successfully completing the practical examinations required by IE Bulletin 83-02.
The modification and repair programs for the RWCU system were in accordance with the required codes and standards, and NRC requirements.