IR 05000312/1979003
| ML19263D557 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/05/1979 |
| From: | Haynes R, Narbut P, Vorderbrueggen NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML19263D556 | List: |
| References | |
| 50-312-79-03, 50-312-79-3, NUDOCS 7904130008 | |
| Download: ML19263D557 (6) | |
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U. S. NUCLEAR RECULATORY CO.W ISSION j
OFFICE OF INSPECTION AND ENFORCEMENT
REGION V
Report No. 50-312/79-03 50-312 DPR-54 Safeguards croup Docket No.
ticense no, Sacramento Municipal Utility District Licensee:
P. O. Box 15830 Sacramento, California 95813 Rancho Seco Facility Name:
Rancho Seco Site Inspection at:
Inspection conducted:
January 11-12, 1979 C-s k S/2/D l
Inspectors:
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Date signed P. P. flarbut, Reactor Inspector oGd lbs b m m w 3/2./79 J'. E. Vorderbrueggen,cf# tor Inspector
/ Dat6 Signed Date Signed
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3/I/79 Approved By:
Date Signed P.. C.'Haynes M f) Project Section, Reactor Construction and Engineering Support Branch Surmary:
Inspection on January 11-12, 1979 (Report tio. 50-312/79-03)
Areas Inspected:
Routine, announced inspection by regional based inspectors of the in-service inspection results pertaining to steam generator tubes and main steam /feedwater containment penetrations, and inspection / repair activities on water hammer induced piping support damage. The inspection involved 31 inspector-hours onsite by two i1RC inspectors.
Results1 fio items of noncompliance or deviations were identified.
RV Form 719 790413 DCO 8
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1.
Persons Contacted A.
Sacramento Municipal Utility District (SMUD)
- R. Oubre, Plant Superintendent
- R.
Colombo, Technical Assistant
- D. Blachly, Lead Plant !!echanical Engineer
- W. Garrett, Plant Mec"anical Engineer
- D. Abbott, Plant llechanical Engineer
- F. Bamford, OC Coordinator
- J. Jewett, QA Engineer J. Sullivan, Plant QA Eagineer J. Parman, Plant Mechanical Inspector C. Lang, Maintenance Foreman B. Hopkins, Welder B.
Bechtel Power Corporation _(Bechtel)
F. Boucher, Senior Stress Analyst
- Denotes those attending exit interview.
2.
In-ser_vice Inspection Data Review and Evaluation The inspectors examined the standard test procedures (STP) 068, Second Refueling Inservice Inspection Program of 11/13/78,which included the requirements for eddy current testing of the steam generators performed by Zetec, other nondestructive testing per-formed by Babcock and Wilcox, and the piping inspection during hydrostatic testing performed by SMUD.
Also examined were the nonconformance reports generated as a result of the work performed for the in-service inspection.
In addition, radiographs of main steam piping welds and feedwater piping welds located within con-tainment penetration sleeves were reviewed.
The foregoing examinations and reviews by the inspector were to ascertain if these activities were performed in accordance with requirements of the licensee's procedures and the inservice in-spection program approved by the NRC.
No items of noncompliance were identified. However, the inspector found that the radiographs of pipe welds located within containment penetration sleeves did not fully meet requirements of the procedure (Procedure No. ISI-300, Revision 8).
Radiography was difficult because the welds were accessible via the limited annular space between the penetration sleeve inner diameter and the piping outer
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diameter.
Radiography was performed on d "best effort" basis according to the licensee's testing contractor.
The contractor devised a special film and source holder which is positioned over
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the weld from a remote position.
These welds are butt welds con-l
necting concentric pipes with different outside diameters.
Although the radiographs did not reveal any unacceptable defects in the
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welds, not all of the attributes required for proper radiography technique were met. Attributes not met included:
area shown on film did not include base material within one wall thickness width p
on each side of the weld, no penetrameter was placed on the thicker
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section of the base material adjacent to the weld, and the film-
source holder device caused a line to be superimposed on the weld image.
It was not evident to the inspector why the above attributes could not be met other than the configuration of the film-source holder.
The licensee stated that this item would be investigated and the information developed would be made available for the inspector's review. This item is considered to be unresolved l
pending review of the results of the licensee's investigation.
(50-312/79-03-01)
l In reviewing the preliminary results of the steam generator eddy current testing, it was noted that denting was observed in the inspection lane tubes at the upper tube sheet in 205 tubes in the
"A" steam generator and in 167 tubes in the
"B" steam generator.
This inspection lane denting was from 1 to 3 mils whereas on the previous inspection the indication had been observed but was so small as to be interpreted as permeability variations.
The licen-see stated that the testing contractor (Zetec) attributed the denting to vibration. Other dents of 5 to 6 mils at the 15th tube support plate were observed in 7 tubes in the
"A" steam generator (excluding the lane area) and in 5 tubes in the "B" steam generator.
Tube denting will be monitored during subsequent testing.
The inspector reported the denting experience to NRC personnel respon-sible for evaluation of steam generator operating experiences.
The inspector had no further questions on this matter.
3.
Piping Supports - Damage from Hydrodynamic Forces On December 15, 1978, the "B" loop of the decay heat system (DHS)
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experienced a " water hammer" event which damaged four supports in the piping associated with the suction side of DHS pump "B."
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occurrence was caused by opening the borated water storage tank
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suction valve to DHS pump "B" after the pump had been started.
The nature of the damage was as follows:
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Support 4S-26101-8 on 12-inch inlet to DHS pump "B" - one of
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two concrete anchor bolts pulled out of the wall and concrete
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was spalled around anchor bolt hole B.
Support 4U-25021-9 on 16-inch supply line from borated water storage tank - all six concrete an: hor bolts pulled from wall and support was displaced from wall approximately one inch.
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Support 4A-20024-2 on 12-inch DHS line from reactor coolant outlet - some concrete spalling around periphery of embed plate to which support is welded.
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Support 4U-25023-1A on 16-inch spent fuel pool cross-tie line between DHS pumps - one of four concrete anchor bolts pulled from wall and the other three bolts were found loose.
In addition, a broken weld was found on a structural angle which is part of a multi-level pipe support structure.
The 16-inch supply line from the borated water storage tank is one of many pipes carried by this structure.
It is questionable that the weld was broken by the hydrodynamic forces associated with this event.
The licensee examined pump "B" discharge piping supports and found no apparent damage.
The licensee also engaged Bechtel Power Corporation, Los Angeles Power Division, to review the damaged supports and perform stress analyses with the objective of iden-tifying any overstressed conditions in the piping and locations where additional supports may be advisable.
Bechtel was also asked to identify specific pipe welds which should be given additional surface or volumetric examination. According to a licensee spokes-man, their search for damage was a visual examination for distress on supports along piping runs to the egress points from the auxiliary building.
The flRC inspectors examined the damaged supports which had since been repaired.
There was no evidence of distress on any of the associated piping. The repairs appeared to satisfactorily restore the supports to the condition which will provide their intended function.
The licensee had documented the damage on nonconformance reports and had issued work requests to effect repairs.
These documents were also reviewed by the ilRC inspectors.
It was noted that nonconformance report No. S-909, dated August 23,1978, re-sulted from an inspection of piping supports which disclosed spalled concrete around the supports identified in B. and C. above.
S-909 report attributed the cause to pipe vibration; however, plant operations personnel have commented to other flRC inspectors on previous occassions about hearing " water hammer" type occurrences in the past. The licensee stated that, in a few cases, concrete expansion anchors which had slipped slightly were retightened rather than replaced.
When questioned about the rationale for that decision, the licensee could offer no technical basi.
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In addition to examining the support repairs, the inspector also talked with the workmen involved in making the repairs.
The only written repair procedures that were utilized were the manufacturer's instructions that accompany the product (concrete wedge anchors and concresive grout). The repair of support 4U-25021-9 involved a modification and there were no calculations or sketches on record to substantiate the modification.
Discussion with the engineer who designed the modification verified, however, that he had followed an acceptable design approach.
The welding procedure used for the modification was verified to be qualified as was the welder who performed the work.
The welding procedure specified the type and size range of material qualified, and the edge preparation and filler metal to be used.
Discussion with licensee personnel also disclosed that there was no involvement by QA personnel in the activities associated with ascertaining the nature and extent of damages or the techniques utilized in accomplishing the repairs.
The inspectors expressed concern about the following aspects of the licensee's handling of the " water hammer" event:
.The apparent informal approach that was followed in detailing the repair measures that were to be accomplished.
.The lack of a more proceduralized approach to making the necessary repairs.
.The absence of QA personnel involvement.
. Examination of other process systsas to identify piping supports that may have experienced some distress from earlier
" water hammer" type events.
.The technical justification for considering retightened concrete expansion anchors to be adequate.
The licensee representatives indicated that they would consider the inspectors' concerns and take appropriate action.
This item is considered to be unresolved.
(50-312/79-03-02)
4.
Exit Interview At the conclusion of the inspection, a meeting was held with the licensee representatives denoted in Paragraph 1.
The observations and findings of the inspectors were discussed.
In connection with
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the " water hancer" event, the licensee pointed out that by the end of April 1979, they had to identify for ilRR those supports to be examined during their next 40-month ISI program, and that they would have to " walk-down" the various systems to make that iden-tification. During that effort, particular care will be taken to observe and document any evidence of pipe support distress.
They also pointed out that consideration would be given to the recom-mendations that are to be forthcoming from Bechtel c.s a result of their involvement in the rec.nt pipe support damage.
The licensee representatives further indicated that they would investigate and report on what had prevented fully acceptable radiographs as discussed in Paragraph 2.