IR 05000249/1980008
| ML17192A722 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/23/1980 |
| From: | Danielson D, Yim I NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML17192A721 | List: |
| References | |
| 50-249-80-09, 50-249-80-9, NUDOCS 8006020077 | |
| Download: ML17192A722 (4) | |
Text
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT Report No. 50-249/80-09 Docket No. 50-249 Licensee:
Commonwealth Edison Company P. 0. Box 767 Chicago, IL 60690 Facility Name:
Dresden Station, Unit 3 Inspection At:
Dresden Site, Morris, IL Inspection Conducted:
April 10-11, 1980
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Inspector:
I. T. Yi~
Approved By:
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D. H.~son, Chief Engineering Support Section 2 Inspection Summary License No. DPR-25 Inspection on April 10-11, 1980 (Report No. 50-249/80-09)
Areas Inspected:
Reactor Water Clean Up (RWCU) pipe system damage due to water hammer; seismic restraint provisions for the Control Rod Drive (CRD) system The inspection involved 10 inspector~hours on site by one NRC inspecto Results:
No items of noncompliance or deviation were identifie soo6o.r0077
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DETAILS Persons Contacted Commonwealth Edison Company* (CECO)
- B. B. Stephenson, Station Superintendent
- R. Ragan, Assistant Superintendent - Operations E. D. Eenigenberg, Assistant Superintendent - Maintenance M. Strait, Engineer, SNED
- Denotes some of those attending the exit intervie Functional or Program Areas Inspected RWCU Water Hammer Damage During the Unit 3 shutdown, the 8" RWCU system between the con-nection of the 16" shutdown cooling line (connecting to a re-circulation loop header) and the drywell penetration was observed damaged perhaps due to water hamme The damage indications ob-served were:
(1) the pipe insulation was cut by distant angle iron, (2) the spring support was off set from center line and (3)
the PSA -10 mechanical snubber was dead bott.omed by forc The cause of the damage was determined to be the sudden opening of the motor operated control valve. (MOV), No. 1201, subsequent to the line drain off in the system downstream of HOV 120 The total repair included:
(1) adding jog control circuits to HOV 1201 to allow control of the valve opening, (2) replacing approximately a 14 foot section of 8" 304 stainless steel pipe with 8" 3161 seam-less of the same schedule where snubbers SR-2 and SR-3 are. attached; including, replacing the attached 3" pipe stanchion with a 4" sche-dule 80 stainless steel section with reinforcement pipe saddle, (3)
replace the 3" pipe stanchion for connecting snubber No. SR-i with a
4" sch. 80 stainless steel with reinforcement pipe saddle, and (4) replace the bottom out snubber SR-3 with a new PSA No. 10 uni In review of documentation and in observation of the repair work, the inspector stated that because of the enormous water hammer force that apparently caused the pipe to jump in a vertical direction more than 5 inches at the horizontal bend near spring support B3-1202, and caused snubber SR-3, to bottom out at the pipe horizontal axial direction, a stress analysis to determine long term effects should be made to cover all areas including piping, fittings~ penetrations, branch con-nections, valves,*and valve operations.* Subsequent to the *
inspection, the licensee informed the inspector that such an analysis would be performed by EDS, Nuclear, San Francisco, CA within approximately four month * The analysis report will be forwarded to RIII for revie This is an unresolved item (249/80-09-01).
In addition to performing a stress ahalySis to ensure long term safe system operation, the licensee was also committed to reinspect the Unit 3 RWCU damage areas by removal of pipe insulation for structural and component deformation, and to observe snubber and spring support conditions during the next plant shutdown with extended period of time two days or mor This is an unresolved item (249/80-09-02). Since a similar RWCU piping configuration exists in Unit 2, and since deficiencies were identified in the inspector's review of the licensee's snubber surveillance records dated October 13-15, 1979, and March 22-23, 1979, the licensee com-mitted to inspect the RWCU system including the snubber condi-tions inside the Unit 2 drywell during scheduled May 1980 plant shutdow The licensee will report any problems found per Technical Specification requirements, and will inform RIII of any change of May, 1980 inspection schedul This is an unresolved item (249/80-09-03). Observation of CRD Suspension Systems The inspector observed the CRD seismic restraints outside and inside the drywell with the following findings: The seismic restraints for all the 6" and 4" horizontal scram discharge headers designed by S&L were welded to a non-seismic category elevated walk grating steel structur The dead weight of the small piping bundles appeared to be adequately supported vertically with rod hangers, and ade~
quately positioned with Unistrut or angle iron spacer However, there were no apparent systematic restraining pro-visions for the piping seismic vertical and horizontal move-ment Inside the drywell, bundles of small p1p1ng were observed restrained for both vertical and horizontal pipe movements at one locatio However, the Unistrut restraint system appeared to have insufficient rigidity for such a large number of small pipes in one are The acceptability of CRD seismic restraint system is considered an unresolved item (249/80-09-04).
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Unresolved Items Unresolved items are matters about which more information is required in order to ascertain whether they are acceptable items, items of non-compliance, or deviation Four unresolved items disclosed during this inspection are discussed in paragraphs 1.a, 1.b, 1.c, and Exit Interview The inspector met with the licensee representatives (denoted under Per-sons Contacted) at the conclusion of t~e inspectio The inspector summarized the purpose and findings of the inspectio The licensee acknowledged the findings reported herei