IR 05000344/1979025
| ML19296B519 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 01/08/1980 |
| From: | Kirsch D, Shackelton O, Sternberg D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML19296B515 | List: |
| References | |
| 50-344-79-25, NUDOCS 8002200744 | |
| Download: ML19296B519 (9) | |
Text
6 U. S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFoRCEME!TT
REGION V
Report No.
50-344/79-25 50-344 flPF-1 Docket No.
tic,ns, go, safeguards Group Licensee:
Portland General Electric Company 121 S. W. Salmon Street Portland, Oreaon 97204 Facility Narre:
Troian Inspection at:
Portland. Oregnn and Ran Francisen_ ralifnenia (Rochtml)
Inspection coq uct3d: Hnvo-bnr %7A anri Dornmber a 1070 Inspectors:
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W)fi rr 11, Reactor Inspector Date syt;ned P.
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. Kirsch, Reactor Inspector Date Signed h Sw bb W
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Date signed 0. C. Shackleton.Investi ator Q Y M 4, < t e <
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/,w,-, f I'7 5 D Approved By:
,G D. M. Sternberg, Chief,rReactor Project Section 1 Dat'e Sfgned
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Reactor Operations and fluclear Support Branch Surrrra ry :
Inspection on November 26-28, and December 4, 1979 (Report No. 50-344/79-25)
Areas Inspected:
Special announced inspection of the circumstances surrounding and corrective actions taken by the licensee as a consequence of licensee event report (LER) 79-15. The inspection involved 60 inspector-hours by three flRC inspectors.
ysults:
No items of noncompliance or deviations were identified.
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.
DETAILS 1.
Persons Contacted Portland General Electric Company J. Aldersebas, Trojan Resident Engineer
- D. Broehl, Atsistant Vice President, Engineering-Construction
- T. Bushnell, Supervising Civil Engineer L. Erickson, Trojan Licensing Supervisor
- F. Greenwood, Quality Assurance Supervisor-Projects S. Hoag, Supervising Mechanical Engineer F. Rogan, Chief Mechanical Engineer - Generation Engineering R. Wehage, Mechanical Engineer Bechtel Power Corporation
- S. Cozzens, Trojan Project Quality Engineer
- L. Damon, Trojan Project Engineer
- T. Flickinger, Quality Assurance Engineer K. Gross, Trojan Civil Group Supervisor V. Mercado, Trojan Plant Design Group Supervisor
- H. florris, Quality Assurance Supervisor, Projects
- J. O' Leary, Trojan Project Manager State of Oreaon
- W. Dixon, fluclear Engineer, Oregon Department of Energy The inspectors also interviewed and talked with other licensee and licensee contractor employees during the course of the inspection.
These included engineers and construction workers.
- Denotes those attending the exit interview on tiovember 28, 1979.
- Denotes those attending the exit interview on December 4,1979.
2.
Inspection Outline On October 19, 1979 Portland General Electric Company (PGE) personnel orally reported an inadequate seismic restraint on the Spent Fuel Pool Cooling System. This report was followed-up by a letter dated October 22, 1979 (CPY-450-79) and by Licensee Event Report (LER) 79-15 dated flovember 4,1979.
Subsequent to the LER additional information was forwarded by PGE to the flRC by letters dated flovember 19, 1979 (Supplement I to LER 79-15) and December 4,1979 (Supplement 2 to LER 79-15).
Based on the possible ramifications of this LER and impact on other licensee activities (IE Bulletin 79-02, and 79-14 as well as the control
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-2-building reanalysis) a special announced inspection was conducted.
The inspectors met with licensee representatives on November 26, 1979 in the PGE Corporate Offices to examine and discuss the status of corrective actions being taken by PGE, to determine the relationship of these actions to activities already completed or underway (ie: IE Bulletin 79-14 &
79-02 Seismic Reevaluation of Control Building), and to verify that the licensee's corrective actions adequately dealt with the concerns addressed in the LER. On November 27, 1979 the inspectors examined the work in progress and interviewed licensee personnel at the Trojan Plant site which were related to LER 79-15. The following day the inspectors examined additional documentation and held additional interviews with engineering personnel at the PGE Corporate Offices.
An interim exit interview wu held at the completion of these activities (in the after-noon of flovember 28,1979).
On December 4,1979 two inspectors visited the Licensee's Architect-Engineer (Bechtel Power Corporation) which was supporting the licensee's corrective actions.
The inspectors questioned the cognizant supervisors and engineers, read the relevant Bechtel procedures for control of these activities, and examined records of completed work as well as work in progress. At the conclusion of these examinations and discussions a final exit meeting was held.
3.
Major Documentation Examined Portland General Electric Letters:
Brochl to Engelken - LER 79-15 dated November 4,1979 Supplement No. 1 dated November 19, 1979 Supplement No. 2 dated December 4,1979 Letter:
Broehl to Schwencer dated November 19, 1979 Letter:
Lentsch to Frank dated November 19, 1979, "Pire Support and Wall Reviews".
Letter:
Broehl to Engelken dated November 21, 1979 - Final response to IE Bulletin 79-02 (Rev.1).
PGE - 1020, dated January 1979 " Report on Design modifications for the Trojan Control Building".
Inter office memo:
Hoag to Wehage dated November 2, 1979 (SEH-23-79M)
"RDC-79-091, Walkdown Guidelines".
Listing of Piping Support Data dated flovember 21,1979 - 4PM.
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-3-Drawing:
SK-M-5069, Rev. A " Concrete block wall walkdown pipe support and penetration locations 146W and 147E."
Generation Engineering Procedure 200-18 " Interim Design Control for Trojan During Control Building Structural Modification" Letters:
Broehl to Engelken - Responses to IE Bulletin 79-14, dated July 17,1979; August 1, 1979; August 31, 1979; and October 30, 1979.
Bechtel Trojan Internal Project Procedure dated June 29, 1973 " Vendor Documentation" Engineering Department Procedures 4.42 Rev. O dated May 13,1977 "Model" 4.27 Rev. O dated December 2, 1977 " Design Verification" 4.26 Rev. O dated December 2,1977 " Interdisciplinary Design Review" Letter & Report:
Friend to Tedesco dated November 15, 1979, " Design Control Program Review" 4.
Inspection Findings (a) Control Building Sei_smic Revaluation On May 5, 1978 the licensee submitted a written report (LER 78-13)
which described three design deficiencies related to the control building walls.
The net effect of these deficiencies was to reduce the shear capacity of the walls to a value less than that stated in the Trojan Final Safety Analysis Report (FSAR). As a consequence the Nuclear Regulatory Commission issued an order dated May 26, 1978, and several persons and groups took the oppor-tunity to intervene. The facility remained shut down while public hearings were held. Duridg these hearings the Atomic Safety and Licensing Board, in considering a request for interim operation by the Licensee, requested that PGE evaluate the effects of the as-built condition of the walls on safety-related components in the plant during postulated earthquakes.
As part of this evaluation the licensee recalculated the seismic response of the control, aux-iliary and fuel buildings and the associated major safety related piping systems.
It must be realized that the loss of shear resistance in the control building would not have resulted in the walls falling down during an earthquake but rather that the motion of the building complex
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-4-(control, auxiliary, and fuel buildings) would be changed from that motion previously analyzed above grade elevation. Modifications to piping supports and restraints were necessary since piping systens previously not in resonance with the building were now calculated to 'oe in resonance and because the calculational uncertainties were increased.
It must also be understood that a wall possesses two types of resistance to external forces. The in-plane or shear resistance (stiffness) of a wall has a large effect on the seismic response of a structure while the out-of-plane or resistance to inertial and normal loads is an important consideration for wall strength (i.e., to resist crumbling or excessive cracking). The shear and normal load resistances are related but are generally verified as adequate at different steps in the design process.
The stresses in the selected piping systems and associated pipe supports and restraints were examined and where code allowable stresses or maximum loads were exceeded new supports (approximately 35) were added or the old support modified (approximately 100). The licensee based the seismic reanalysis on the plant as built drawings and Drawing Change notices that existed at that time.
In these cases the wall strength was examined to verify the wall could take the increased loadings. Where the piping support loads were not increased it was assumed that the associated wall could withstand the support loadings.
The additional pipe support work was completed, under licensee Request for Design Change (RDC)78-095, in November / December 1978 and interim operation started in January 1979.
Since the control building design and construction must ultimately satisfy the criteria of the FSAR, PGE personnel have stated that they intend to reevaluate the building complex based on the final as built design. This final revaluation is partially completed with the result that approximately 155 additional restraints or supports will require modification. About 76 of these modifications have been completed under RDC 79-028. To date while doing this work four loca-tions have been identified where the design of the restraint or support had to be modified to prevent overloading a wall to which the restraint was (to be) attached.
(b)
I&E Bulletin 79-02 " Pipe Support Base Plate Design using Concrete Expansion Anchor Bolts" I&E Bulletin 79-02 was issued to PGE on March 8,1979. This bulletin required each licensee to examine the design application of concrete anchor bolts in light of criteria contained in the bulletin and to s
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-5-examine quality control (QC) records and/or conduct a sampling pro-gr-of installed anchor bolts to verify that the concerns raised
, ae bulletin were properly dealt with.
Subsequently, one supplement and two revisions of the bulletin were sent to the licensee. Out of 1454 safety related supports,11 were discovered
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to have safety factors less than the minimum specified by the Bulletin (2) and 69 with safety factors unsuitable for long term operation (2 to 5).
In addition the licensee's sampling program field tested 1608 out of 7947 anchor bolts total with a result of 93 defects requiring repair.
The repairs generally consisted of installing larger anchor bolts or to bolt to a steel plate on the far side of the wall.
If neither of these approaches was feasible then the support / restraint would be attached to some other structural component (i.e., floor, steel beams, etc).
While correcting the eleven unacceptable supports previously mentioned PGE discovered that the wall to which one restraint (HCC-48-2-SA-83) was attached could not accept the calculated load imposed on it by this support.
Initially PGE engineers believed that bolting the restraint in the wall with bolts through the wall would provide adequate support. Upon examination of the effect on the wall it was determined that although the restraint was satisfactory the wall could be damaged during a seismic event.
Before this discovery PGE engineers were examining the capacity of structures to support pipe support or restraint loads only when a new support / restraint was added or when a significant modification (due to increased loads) was required. The support (SA-83) was a seismic restraint for a 10 inch pipe connecting the spent fuel pool cooling system to the Residual Heat Removal (RHR) System and was attached to a double masonry wall separating the two RHR rooms below grade. The licensee corrected the situation by moving the support to adjacent walls which were stronger and by examining all other masonry walls for this kind of problem. This is documented in LER 79-15 dated November 4, 1979.
PGE representatives stated that all anchor bolts with a safety factor less than two would be repaired or replaced prior to start-up and all anchor bolts with a safety factor between two and five would be repaired or replaced during the next refueling outage (currently scheduled for late spring of 1980). The status of the work related to IE Bulletin 79-02 (including Supplement 1, Revision 1, and Revision 2) is (as of the dates of the inspection) summarized in the licensee's letter dated November 21, 1979.
(c)
ISE Bulletin 79-14 " Seismic Analysis for as-built Safety Related Piping Systems".
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-6-IE Bulletin 79-14 was issued to PGE on July 2,1979.
This bulletin required each licensee to verify that the seismic analyses of safety related piping systems were consistent with the as-built condition of the plant. One revision and two supplements to the bulletin have been subsequently issued to clarify the bulletin's requirements.
The licensee's personnel decided to walk-doun safety related piping systems and to note any discrepancies on appropriate piping drawings.
The majority of discrepancies ob-served were geometrical in nature (for example: a length of pipe between supports was 9'6" vice 11'2" +6" or a restraint was 2' from an elbow vice l'3" +6") and were evaluated by engineers at the plant site. As of the date of this inspection, all walkdowns have been completed (with the exception of one train of safety related equipment inside containment) and field evaluations of this work have been completed. The final verification of walkdown results and associated seismic reanalyses are not yet completed due to shortages of stress analysts.
However, the licensee has committed to finish the walk-downs during the next refueling outage with a final follow-up report to the NRC about 3 months later. The purpose of these walkdowns and analyses was to verify that the seismic ar.alyses of safety related piping systems are accurate, complete and are consistent with the actual plant.
The strength of plant walls was outside the scope of the IE bulletin and PGE's associated program unless an original seismic analysis was found to be in error, thereby increasing the load on a given wall (requiring reanalysis of the piping support / restraint and the associated wall). As of the date of this inspection the licensee had identified aonroximataly 75 minor deviations not requiring remedial action which are being documented by Drawing Change Notices lCN) and seven nonconformanus which re-quired some remedial corrective action. The corrective actions were generally to repair (replace missing nuts etc.), tishten, or loosen existing restraints.
One item (a support of the contain-ment soray system had slipped off a sliding pedestal) was identified by PGE personnel to be reportable to the fRC. This item was reported to the NRC by means of LER 79-13.
PGE's letter dated October 30, 1979 sums up the status of the work related to IE Bulletin 79-14.
(d) Licensee Event Report 79-15 Masonry Wall Problem While examining the design of restraint HCC-48-2-SA-83 as reouired by IE Bulletin 79-02 the licensee's personnel found that the wall associated with that restraint could be damaged by the forces transmitted during seismic events described in the FSAR. As a consequence, PGE under-took a complete field survey of all safety related walls to map
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-7-restraints, supports, and large loads (>100 lbs) attached to each wall to verify adequate wall strength. This data was then sent to Bechtel (the licensee's Architect-Engineer) to examine the effects on all single and double masonry walls as well as, selected heavily loaded composite (double masonry with a central core of concrete)
and solid concrete walls.
In addition, the licensee personnel have planned to examine (with Bechtel's assistance) selected heavily loaded floor and structural steel members to verify adequate consid-eration was given to the effects of pipe and equipment loads on these supporting structures.
Bechtel is also providing services to the licensee for the control building seismic revaluation, IE Bulletin 79-02 evaluations and IE Bulletin 79-14 walk-down and reanalyses.
While testing masonry / composite walls to demonstrate that
^the block cores were filled and that an adequate bond existed between double nasonry as well as masonry to core concrete, PGE personnel discovrx that some double masonry walls did not have complete mortar contact between walls.
This problem appears to be due to a scope of work disagreement between the licensee and a subcontractor which occurred between April and September of 1972. The licensee has committed to test all double masonry walls built during this period and to fill all voids with non-shrink grout.
For conservatism, and to avoid potential disagreement with the flRC, the licensee personnel decided to take no credit for the tension transfer capacity of the mortar between double masonry walls for the purpose of pipe and equipment support loads. The licensee's evaluation of the effects of wall support loads in conjunction with this criterion resulted in a total of 126 modifications to piping supports (in 43 cases through-bolts on the walls could be used, in 83 cases the wall was off-loaded altogether).
PGE personnel have stated that all these modifications would be completed prior to plant start-up. The principle cause of these modifications is the assumption that no tension can be transmitted through the mortar of the double masonry walls and a revised method of calculating allowable stresses in the wall.
The problem with SA-83 could be attributed to inadequate design interface between the Civil and Plant Design Groups in Bechtel; however there is evidence on design drawings that this kind of interface information was routinely comunicated between groups and guidance (i.e. Bechtel Standards) to these groups regarding interfacing comments was available. After about March 1974 the potential problem at Bechtel was obviated by adoption of tne "Engi-neering Department Procedures" which require inter-disciplinary coordination and documentation of these reviews.
PGE and Bechtel
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-8-procedures appeared consistent with the regulatory requirenents which existed at that time.
Bechtel has investigated the design control practices used in designing structures to withstand pipe hanger loads for thirteen plants designed between 1963 and 1974.
The report indicates that masonry walls were used to support large category 1 pipe for Peach Botten 2 & 3, Pilgrim 1, Arkansas 1,
!!illstone 2, Davis Besse 1, and Duane Arnold. The investigation concluded that the projects selected had documented procedures or requirements for interdisciplinary coordination, that these were followed, and that they were adequate.
No items of non compliance or deviations were identified.
5.
Exit Interview The inspectors met with licensee personnel on November 28, 1979 in the PGE corporate offices and with Bechtel and PGE personnel in Bechtel's San Francisco offices on December 4,1979 to review the scope and findings of the inspection.