IR 05000423/1993016
| ML20057C067 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/09/1993 |
| From: | Gray E, Patnaik P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20057C065 | List: |
| References | |
| 50-423-93-16, NUDOCS 9309270028 | |
| Download: ML20057C067 (8) | |
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U. S. NUCLEAR REGULATORY COMMISSION
REGION I
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REPORT NO.:
93-16
DOCKET NO.:
50-423 LICENSE NO.:
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LICENSEE:
Northeast Nuclear Energy Company FACILITY NAME:
Millstone Unit 3 INSPECTION AT:
Waterford, Connecticut INSPECTION CONDUCTED:
July 26 - 30 and August 10 - 13, 1993 P
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INSPECTOR:
P. Patnaik, Reactor Inspector, MS Date EB,DRS
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I/1 APPROVED BY:
E. H. Gray, Chief,%aterials Section Date
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Areas hispected: Review portions of the inservice inspection program, scope of ISI work for the outage, and witness non-destructive examinations related to inservice inspection.
Also, the steam generator examination plan and procedures were reviewed and eddy current examination activities of steam generator tubes were observed.
Results: The non-destructive examination program related to the inservice inspection was found to have a minor weakness in the lack of proper control of the calibration blocks in that when an alternate calibration block was selected to meet a change in the ASME Code, the need for a revision to the NRC approved ISI program was not documented. Prior to the start of the outage, a deficiency was noted in the scope of the outage plan due to the percentage of
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welds scheduled for inspection by the end of the second period being below the requirement.
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of the ASME Section XI Code. This was, however, corrected during the inspection by increasing the scope of work for the outage. The inservice inspection program during the outage was found to be in compliance with the applicable ASME Section XI Code and the regulatory requirements. The licensee exercised adequate control over mservice inspection activities during the outage. The cddy current examination program met the industry standards and the regulatory requirements.
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1.0 INSERVICE INSPECTION (ISI) (73753)
1.1 Scope The conduct of inservice inspection using ultrasonic, magnetic particle and liquid penetrant examination ensures integrity of the pressure boundary. During this inspection, reviews of the ten-year ISI plan, the scope of work for the outage, a sampling of inservice inspection data, and observation of work activitics were performed to ascertain if the requirements of the applicable ASME Code,Section XI, and the Technical Specifications were met.
1.2 Findings Northeast Nuclear Energy Company (NNECO), the licensee for Millstone Unit 3, conducted an inservice inspection during the fourth refueling outage of the unit in accordance with the ASME Code,Section XI,1983 edition, including the summer 1983 addendum. However, the inspection of Class 2 pipe welds has been updated to the 1983 edition ASME Code,Section XI, including the winter 1985 addendum. The unit is in the second inspection period of the first inspection interval, and the ongoing outage (fourth refueling) is the last outage of the second period. The inspector reviewed the ten-year ISI plan and the relief requests to the NRC on welds which are impractical to examine in accordance with the applicable Code.
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Within the scope of the review, the inspector did not find any discrepancy. The licensee identified appropriate welds which were beyond the scope of the Code examination through an augmented inspection plan.
The scope of work in regard to inservice inspection for the outage was reviewed. The inspector found a deficiency that for the ASME Code,Section XI, categories B-K-1 (Class 1,
" Integral Attachments for Piping, Pumps and Valves"), C-F-1 (Class 2, " Pressure Retaining Welds in Piping), and C-G (Class 2, " Pressure Retaining Welds in Pumps and Valves"), the licensee did not meet the minimum percentage of welds to be examined by the end of the second period, as required by the applicable ASME Section XI Code. Hence, the licensee increased the scope of work during the inspection to comply with the Code.
The level of staffmg to implement the inservice inspection program was found to be adequate. The licensee used an elaborate and systematic method of reporting, evaluating, and dispositioning unresolved non-destructive exarnination (NDE) indications as detailed in
" Nuclear Engineering and Operations Procedure NEO 3.13, Inservice Inspection Unresolved Indication Reporting "
The non-destructive examination program at Millstone 3 was reviewed in regard to the inservice inspection of Class 1 and Class 7 components. The inspector reviewed the following procedures:
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Ultrasonic Examination-Austenitic and Dissimilar Piping Welds, NU-UT-2, Rev. 8
Ultrasonic Examination-Ferritic Piping Welds, NU-UT-3, Rev. 7
Ultrasonic Examination-Thickness Measurements for Erosion / Corrosion, NU-UT-30,
Rev. 8 The inspector noted that the procedure for thickness measurement (NU-UT-30) did not provide for disposition of components, which could not be examined due to geometric conditions, such as unparallel surfaces. This finding was resolved by the licensee during the inspection by issuing a change notice (NU-UT-30-1) to this procedure, which requires that components with unparallel surfaces shall be noted on the calibration sheet. Also, utilization of any special features of the ultrasonic examination equipment (e.g., extended blank, echo to echo mode) shall be noted and detailed on the calibration data sheet with sketches, as necessary. The above procedures were found to be in compliance with the ASME Section XI Code, and had appropriate reviews and approval by various individuals.
The certifications of NDE personnel were readily available in the file. All NDE personnel were appropriately qualified in accordance with SNT-TC-1 A requirements.
The Quality Services Departrnent (QSD) of NNECO has certified NDE personnel in the staff who performed surveillances of NDE activities and repeat a sample of examinations during the conduct of the inservice inspection in the outage.
The inspector witnessed the magnetic particle examinations of the feed water piping system welds Nos. FWS-18-FW-63, FWS-13-FW-64, and FWS-15-FW-10. The inspector also witnessed the ultrasonic examinations of feed water piping welds Nos. FWS-18-FW-13, FWS-17-FW-6LM, FWS-18-FW-31, FWS-18-FW-29, FWS-16-FW-30, and FWS-ll-FW-10.
The inspector interviewed the examiners who performed the non-destructive examinations and determined that they were familiar with the test procedures and the Code requirements.
The inspector performed surveillance of the storage area for the ultrasonic calibration blocks.
The storage facility appeared to be adequate. However, a visual examination of some of the calibration blocks revealed corrosion of internal surfaces of the holes and the notches, along with general corrosion of external surfaces. The inspector noted the possible detrimental effect of such corrosion in the reference reflectors. Although no degradation of response from the calibration reference reflectors was noted, the licensee stated that steps would be taken to provide for adequate corrosion protection of the blocks. This is an unresolved item (URI 423/93-16-1).
The licensee controlled the use of calibration blocks through unique identification numbers assigned to each block, which are referenced in the ten-year ISI plan and the outage plan.
The ISI plan correlates each weld to the appropriate calibration block. The ISI plan is a controlled document, which requires review and approval of changes. However, it was
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5 noted that t1e feed water system component (FWS-18-FW-13) weld was ultrasonically examined udng a block identified as Irr-30 instead of the block CWY 33 that is referenced -
h in the ten-year plan. The licensee did not have a cross-reference between t ese two calibration blocks, nor had they issued a controlled change to the ISI plan. During outage planning, the applicable ASME Code requirements for the calibration block used for this weld were revised, and block PT-30 was selected in place of CWY-33 to accommodate the Code revision, however, the need to update this ISI program was not documented. This is another unresolved item of this inspection (423/URI 93-16-2).
1,3 Conclusion The licensee exercised adequate control over inservice inspection activities during the fourth refueling outage of Millstone Unit 3. However, the NDE program related to the inservice inspection was found to have a minor weakness due to lack of proper control of the calibration blocks.
A deficiency was noted in the scope of the outage plan due to the percentage of welds scheduled for inspection by the end of the second period being below the requirement of the ASME Section XI Code. This was, however, corrected during the inspection by increasing the scope of work for the outage. The inservice inspection program during the outage was found to be in compliance with the applicable ASME Section XI Code and the regulatory requirements.
2.0 STEAM GENERATOR EDDY CURRENT EXAMINATION-The steam generator eddy current examination of Millstone 3 was in progress during the
'I inspection. The licensee selected the A and C steam generators, which were not examined during the past refueling outage, for eddy current examination during this outage. The licensee planned to examine sixty-five percent (3,660 tubes) of the total number of tubes (5,630 tubes) in each generator for the full length of the tube using a bobbin coil probe. The sample of tubes selected for the bobbin coil eddy current examination was comprised of the following:
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S/G A S/G C Tubes with flaws greater
4 than 20% thru wall found in 1989 Perimeter and row 1 tubes 282 289 Tubes not tested in 1989 3,069 3,144 Random rows greater than 289 223 25 examined in 1989 for AVB wear TOTAL 3,660 3,660 The licensee has also planned to examine 100 tubes in each generator using a rotating pancake coil in inner row U-bends, straight tube lengths, and the top of the tubesheet.
During this inspection, the licensee's data acquisition and some resolution of data due to differences between the primary and the secondary analysis were witnessed. These activities were performed in accordance with the licensee's procedure and the data analysis guideline.
A review of the licensee's cddy current examination procedure and the data analysis guideline indicated that these documents meet the applicable ASME Code and the industry standards. The personnel performing the examination were appropriately certified in accordance with SNT-TC-1 A requirements and were also trained and examined on the Unit 3 site specific steam generator tube materials and conditions.
2.1 Conclusions For these areas inspected, the eddy current examination program met the industry standards j
and the regulatory requirements.
3.0 FAlllD ANCIIOR BOLT FOR QUENCil SPRAY PUMP On July 12,1993, an anchor bolt from one of the quench spray pumps was found to have broken off. There are ten anchor bolts for each pump conforming to ASTM A 540 Gr. B21, Class 2 material that hold down the pump to its foundation. The licensee performed an ultrasonic examination of nineteen bolts and determined that the structural integrity of the
remaining bolts have not been affected. The broken bolt was sent to a laboratory for failure analysis. It was determined that the failure mechanism was stress corrosion cracking. The l
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licensee plans to replace twenty ASTM A 540 Gr. B21 bolts in both quench spray pumps with A 193 Gr. B7 material, which is less susceptible to stress corrosion cracking than the A 540 bolting material. This replacement will be done during the current refueling outage.
The licensee further investigated to determine the extent of use of A 540 bolting in other safety-related systems of the plant. It was established that the reactor vessel closure studs, the reactor coolant pump (RCP) closure bolts, and the RCP No. I seal bolts are also made of ASTM A 540. However, these bolts are routinely inspected in accordance with the ASME
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Section XI Code under the inservice inspection program. The inspector concurred with the licensee's root cause evaluation and ultimate disposition of the bolting issue.
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4.0 INSTALLATION OF PERMANENT REACTOR CAVITY SEAL
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During the inspection, installation of a permanent reactor cavity seal, a device to prevent
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ingress of refueling water into the reactor cavity, was in progress. The inspector was notified of a work stoppage by the licensee, due to inadequate welding quality on the joint between the flexible membrane and the vessel flange extension. The licensee required the welding contractor to take effective corrective actions to upgmde control and performance
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of the welding and provided for removal and replacement of the questionable welding.
The inspector performed a visual inspection of the welds and interviewed cognizant
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personnel. The licensee's action to stop work and require the welding contractor to put appropriate corrective actions in place was appropriate and timely. The weld at issue was
ground out, rewelded, and determined to be acceptable by liquid penetrant examination and visual examinadon.
5.0 ENTRANCE AND EXIT MEETINGS j
Members of the licensee's management, engineering, and technical staff were informed of i
the scope and the purpose of the inspection at the entrance meeting which took place on July 26,1993. The findings of the inspection were presented to and discussed with members of j
the licensee's management at the conclusion of the inspection on August 13,1993. The licensee concurred with the findings of the inspection. A list of attendees of the exit meeting is attached to this report as Attachment 1.
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ATTACIIMENT 1 EXIT MEETING ATTENDANCE Millstone NucIcar Power Station L. Bigalbal, Licensing F. Dacimo, Director R. Fuller, Nusco Ixvel III D. Harris, Licensing Engineer A. Koehl, ISI
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L. loomis, ISI D. MacNeill, ISI Coordinator
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D. McDaniel, MP3 Engineering t
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R. Arrighi, Resident Inspector J. Durr, Branch Chief E. Gray, Section Chief P. Patnaik, Reactor Inspector A. Ray, Reactor Engineer
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