IR 05000255/1990003
| ML18057A369 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 08/09/1990 |
| From: | Danielson D, Jeffrey Jacobson, Liu W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML18057A368 | List: |
| References | |
| 50-255-90-03, 50-255-90-3, NUDOCS 9008130306 | |
| Download: ML18057A369 (11) | |
Text
U. S. NUCLEAR REGULATORY COMMISSION
REGION III
Report No. 50-255/90003(DRS)
Docket No. 50-255 License No. DPR-20 Licensee:
Consumers Power Company 1945 West Parnall Road Jackson, MI 49201 Facility Name:
Palisades Nuclear Generating Plant Inspection At:
Palisades Site, Covert, MI Bechtel Power Corporation, Gaithersburg, MD Universal Testing Laboratory, Chattanooga, TN Inspection Conducted:
January 22-25; April 12; June 4-8; and July 16-20, 1990 - Bechtel Power Corporation February 6-7, 1990 - Universal Testing Laboratory May 3, 1990 - Palisades Site
- Approved By: ~'74-1,,l,4./VUJ~-J-t-c..~
D. H. Danielson, Chief Materials and Processes Section Inspection Summary c8/og/;c Date
~Mo Date Inspection from January 22 through July 20, 1990 (Re ort No. 50-255/90003lDRS))
Areas Inspecte : Specia sa ety inspection o structura analyses associated with the containment construction opening, an evaluation of rigging loads, and a review of the narrow gap welding process (37701).
Result~: Of the areas inspected, no violations or deviations were identifie During the course of the inspection, the following strengths and weaknesses of the design activities were noted:
- ~.' () u :::: () *:;.
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Strengths
0
0 Both the licensee 1 s engineering staff_ and Bechtel's engineering personnel appeared to be technically competent and well motivate The overall engineering program associated with the structural analyses for the containment modifications appeared to be comprehensive and acceptabl The findings of the quality assurance audit were goo There appeared to be a high degree of involvement of both the licensee's and Bechtel's management in all aspects of design-and construction associated with the steam generator replacement activitie Weaknesses
0
The effectiveness of the design checking process is questionabl A lack of attention to design input and design calculations was found in the piping stress analyses, and Bechtel's structural analyses associated with the rigging load Independent design verification for the containment construction opening analyses app~ared to lack technical thoroughness.
- DETAILS Persons Contctcted Consumers Power Company (CPCo)
+*J. Kuemin, Staff Licensing Engineer
- K. Chao, Staff Engineer
+P. Flenner, Staff Welding Engineer Bechtel Power Corporation (BPC)
- A. Beckman, Project Manager
- +*R. Beck, Assistant Project Manager
- J. Whitcraft, Chief Civil Engineer
- D. Kansal, Manager, Quality Assurance
- G. Brown, Project Engineer
- E. Thomas, Assistant Chief Civil Engineer
- J. Wang, Civil Supervisor
- T. Tai, Nuclear Supervisor
- P. Dadlani, Project QA Engineer
- S. Sae-Ung, Senior Engineer
- J. Roberts, Structural Engineer
+T. Wiesner, Welding Engineering Supervisor
+F. Hopple, Welding Engineer
.#A. *Wyche, Licensing Engineer Universd1 Testing Laboratory (UTL)
+A. Curtis, III, Vice President, Technical Operations
+E. Bruckner, Welding Engineer Nuclear. Regulatory Commission (NRC)
- B. Holian, Palisades Project Manager, NRR
- C. Tan, Civil Engineer, NRR
- T. Rowell, Summer Intern, NRR
+O. Danielson, Section Chief, DRS, RIII
- Denotes those who attended the interim exit interview on June 8, 1990, at the Bechtel Power Corporatio #Denotes those attended the exit interview on July 20, 1990, at the Bechtel Power Corporation.
. +Denotes those who attended the exit interview on February 7, 1990, at the Universal Testing Laborator ** *
Containment Construction Opening (37701)
The steam generator replacement activities require that a construction opening through the wall of the containment shell be provide The approximate size of this opening is 26 feet wide and 29 feet high, and it is located at the southeast quadrant of the containmen After the completion of the steam generator replacement, the construction opening will be closed and restored to its original design conditio To ensure the structural integrity of the containment during the construction opening period and after the closing of the construction opening, Bechtel has performed a series of 18 calculations based on the original design criteria provided in the FSAR to demonstrate that the structural adequacy of the containment is maintaine Calculation C-025, Model Description A three dimensional finite element model composed of approximately 1,400 quadrilateral shell elements and 1,401 nodal points was used for the conta4nment mode The Bechtel Structural Analysis Program (BSAP) was used to perform the analysis of this mode The BSAP is a general purpose finite element computer program for ~nalysis of structural systems subject to static, dynamic, and thermal load The following analytical models were developed to account for the construction sequences associated with the containment modification:
1)
Before modification - the e~isting containment with the tendons partially removed just before the wall opening is cu )
During modif1cation - the affected containment tendons have been detensioned and the wall opening is cu )
After modification - the containment wall opening has been closed and the affected containment tendons have been fully retensione Calculation C-026, Load Combination for the Containment Shell The load combinations used in the analysis are consistent with the load combinations specified in the FSA The load combinations needed to be considered are for the conditions of (1) during the existence of the construction opening; and (2) after the permanent closing of the construction openin It was noted that the crane loads, wind loads, and the seismic loads were independently combined with dead loads and prestress loads during the existence of the construction openin Calculation C-031, Crane Loading on the Containment Shell There are two elevations where rigging loads are transferred to the cor1tainment shel At the construction opening, the runway loads
are given at two point The loads at each point are 11.0 Kips,
-352.0 Kips, and 9.0 Kips in the x, y, and z directions, respectivel The maximum rigging loads at the top of the polar crane rail are 21.6 Kips, -252.5 Kips and 6.8 Kips in the radial, vertical, and tangential directions, respectivel The above rigging loads were used for the analy~is of the polar crane bracket assemblies and the containment shell with the construction opening in plac Calculation C-030, Seismic Loads for the Containment Shell Structural Analysis The maximum seismic accelerations occur at the top of the containment shell. These maximum accelerations were specified as 0.205g for OBE and 0.355g for SSE from the FSAR and were used for the analysis of the containment shell structure. Also, these accelerations were utilized at all elevation Therefore, the seismic analysis for the containment shell structure including the construction opening was performed in a conservative manner in terms of a safety consideratio Calculation C-038, Adequacy Evaluation of the Containment Shell After the Construction Opening Repair The containment shell stresses obtained from the finite element analysis were used for the structural adequacy evaluatio There were li load combinations in the structural analysi The results for each of the 11 load combinations were reviewed for design adequacy in terms of meeting the stress criteria set forth in the FSA It was concluded that the repair of the containment construction opening would restore the containment to the same level of structural integrity as that specified in the original desig Calculation C-039, Adequacy Evaluation of the Containment Shell During the Construction Opening *
The structural adequacy evaluation of the containment shell with the exisience of the co~struction opening was performed based on the design criteria contained in the FSA There were eight load combinations in the structural analyse The results for each of the eight load combinations were reviewed for design adequacy in terms of meeting the intent of the FSAR requirement It was concluded that the structural integrity of the containment shell can be maintained at the same level as that specified in the original design during the period of the construction openin Based on the above reviews and a number of discussions with the licensee 1 s technicaJ staff and Bechtel 1 s engineering personnel, the NRC inspector concluded that the structural integrity of the containment shell can be mctintained during the period of the construction opening and after the construction opening has b~en closed. *
No violations or deviations were identifie ** Calculation C-053, Com arison of the Analysis Results Between the Original and the Present Mode s 37701 The finite element analysis of the containment shell uses three dimensional thin plate or shell element theor The containment shell is assumed fixed at the basema This model is referred to as the present analytical mode The original finite-element analysis of the containment shell used plane strain elements and considered basemat flexibility. This model is referred to as the original analytical mode Calculation C-053, dated June 6, 1990, concluded that the results from both analytical models were comparabl However, the hoop and meridional bending moments at the base of the containment shell from the present model were significantly smaller than the same moments from the original mode Based on this information, the NRC inspector questioned the conclusion of the calculatio The meridional bending moments at the base of the containment shell for the present analytical model should result in larger moments than the original analytical model in accordance with structural theor The inspector further noted that the moments shown in Figure 5 for the present analytical model were not in agreement with moments shown in Figure 6 for the original analytical mode The inspector held discussions with the licensee's technical staff and Bechtel's engineering personnel regarding these concern It was determined that the moments and forces were taken at the center of the elements rather than at the attachment to the basema The difference between the two locations is approximately 4.5 fee As a result of the discussions, Bechtel's engineering personnel agreed to revise the improper statement contained in Calculation C-053 and to conduct further evaluations of the situatio Revisio11 1 of Calculation C-053 was completed by Bechtel on June 18, 199 The NRC review of this calculation found that the moments in Figures lC and 2C showed great difterences between the present model and the original mode Notably, the moment at ~he basemat from the recent analysis was 1,311 ft.-Kips compared with 186 ft.-Kips from the original analysi There was no justification to ensure that the existing containment structure could withstand large moments derived from the present model analysi When questioned, licensee representatives agreed to perform additional calculations to verify the structural integrity of the containment under these large moments when combined with other load These additional calcu-lations were documented in Calculation C-06 No violations or deviations were ~dentifie.
Calculation C-064, Adequacy Evaluation of the Containment S ring Line and Shel Base Regions 377 1)
As discussed in Paragraph 3, above, the pu~pose of this calculation is to evaluate the structural adequacy of the containment based on the moments derived from the current model analysi The preliminary evaluations of this calculation were documented by Bechtel on July 19, 199 Results from this evaluation revealed that the calculated maximum stress at the basemat region was 2% greater than the allowable limit and at the spring
line (do.me elements) was 99% of the allowable valu Because of the conservative nature of the analysis, it was concluded that the existing containment structure during the modification and after the modification can still withstand the maximum design loads per FSAR requirement No violations or deviations were identifie.
Rigging Loads Evaluation (37701) Calculation C-002, Structural Adequacy Checks for Rigging Loads on Polar Crane Brackets The purpose of this calculation is to verify structural adequacy of the existing polar crane bracket assemblies under the maximum lifting loads of steam generator The existing polar crane bracket assemblies were originally designed for a lifting capacity of 250 Kip The proposed semi-gantry crane, which is to be used in lifting the steam generators, will have a capacity of more than 1,034 Kip Consequently, the existing polar crane bracket assemblies must be verified for-structurai adequacy with respect to the increased load During the review of this calculation, the NRC inspector noted that the calculated stresses for several members of the bracket assemblies were from 99% to 100% of the allowable stress limit Since the calculated stresses were close to exceeding the applicable Code allowables, the NRC inspector requested that the accuracy of the design drawings for the bracket assemblies be field verified. This verification is to ensure that the design drawings used in the stress analysis are consistent with the actual installatio In response to the NRC's concern, Bechtel issued a memorandum dated July 27, 1990, to ensure that the field verification is implemented. This concern is considered resolve During the inspection, the NRC inspector noted that Calculation C-002 contained several design error One ~xample was on Sheet 46 where compressive forces were calculated in structural attachment bolt The other was the lack of attention to the units for calculation of moment of inertia shown on Sheet 3 Although these errors were not safety significant, they give an overall indication of a lack of attention to detai Bechtel agreed to correct the above errors in tne next revision of the calculatio Review of Load Test Rigging International Company performed the evaluation of the lifting systems associated with the steam generator replacemen In accordance with Rigging International D~awin~s 1836-206, 1836-216, and 1836-217, the weight of the existing generator is 924 Kips and the weight of the new generator is 922 Kip The design analysis was based on a static load of 940 Kip The test load, consistent with ANSI N45.2.15 requirements, is 110% of the static load and is equal to 1034 Kip Instructions and procedures were specified on the
aforementioned drawings to control test activitie In addition, all Rigging International calculations associated with the steam generator replacement were reviewed by Bechtel for additional assuranc Maximum loads from the gantry crane assembly were distributed to the existing structures inside the containmen These structures were reviewed with respect to the maximum imposed loads to ensure that they were able to perform their required safety function No violations or deviations were identifie.
Quality Assurance Audit Review The NRC inspector reviewed Consumer Power Company Audit Report N SGRP-SV-90-A This audit was conducted February 5 through 9, 1990, at the Bechtel Power Corporation office in Gaithersburg, Marylan This audit was planned and performed as a joint team effort, with the team consisting of four members from Consumers Power Company and three from Bechte The purpose ot the audit was to assess engineering activtties associated with the Palisades Steam Generator Replacement Progra The audit team reviewed a significant number of items, interviewed several Bechtel personnel, and discussed many questions and concerns with project management and quality staf As a result, the team identified six findings and 23 observation Examples of several findings and observations are noted below: Finding No. 1 Because of similar deficiencies in several p1p1ng stress calculation packages, it was concluded that, even though the stresses and supports appeared to be within allowable limits, the use of incorrect methods and other criteria constituted a fa-ilure to correctly translate design bases into design document Finding No. 2 The review of several specifications prepared for this project identified many discrepancies, inconsistencies and possible omission These examples represented a failure to correctly translate design bases into design document * Observation No. 2 Calcula~ions SGAR-PD-H5, SGRP-PDH-001, and SGBB-PD-H5 contained computer printouts in which changes were made in pencil by the ori*ginator to provide clarifications, justification for minor input errors or hand calculations where the printouts did not completely address a particular paramete These changes were not initialled or si.gned/dated to indicate if they had been made,by the originator or the. checke All changes to calculations should be signed and dated by the person making the notatio * Observation No. J For the calculations identified in Observation 2, bolt allowables were used from the applicable vendor catalog, but the catalog was not listed as a.reference.'. Discussions with the responsible engineer (RE) indicated the data would be included in the design criteria, but this has yet to be issue The calculation should stand on its own in the absence of the design criteria, and the design criteria should properly reference the source of the cited data when it is finally issue Similarly, the calculations do not give a source for the assumption concerning 11 4000 psi concrete".
The RE indicated the
.actual source to be the Palisades FSAR, and that this would be reflected in the plant design specification for design criteri Observation No. 22 Review of Bechtel and Rigging International calculations in the civil design area resulted in several concerns:
(1)
Bechtel calculations referenced vendor calculation and drawing numbers that are not consistent with those in the Supplier Document Registe (2)
It is not clear that Bechtel calculations that used vendor results as input are keeping up with the latest versions of the vendor's sour~e calculation, nor is it clear that there is a mechanism to assure this happen (3)
Vendor calculations are not titled, and there is little explanatior1 for the purpose, sources, or conten (4)
Vendor calculations did not clearly document the originator or issue date, and did not show evidence of having been checked or approve (5) It is not clear that Bechtel has established a mechanism to account for the fact that several Rigging International (RI)
calculations may derive the same number used as input to a Bechtel calculation, but the values are not compared and assurance cannot be given that the latest value gets into the Bechtel calculatio (6)
It is not clear that Bechtel has established criteria to determine when a vendor originated calculation may need thorough review by Bechtel prior to use as input to a Bechtel calculation; this could be troublesome given the situation described in item ( 4).
In view of the above audit findings and observations, it appeared
.
that the audit activities were well performed in terms of identifying a significant number of problems and concerns associated with the steam generator replacemen Bechtel was requested by the licensee
- .
to include in its response to each audit finding and observation, the cause of the condition, and the actions taken or planned to correct and prevent its recurrenc Independent Design Verification The independent design verification for the containment construction opening was completed on June 28, 1990, at Bechtel 1 s Pottstown offic The design verification was performed in accordance with the requirements of EDPI 4.27-39, dated March 26, 199 The purpose of the verification was to assure that the containment opening was adequately designed and integrated into design document The verification staff noted that the new model more accurately reflected the configuration of the containment structure. 1he new model also included a fixed basemat, simplified ring girder and the buttresse However, the verification staff did not identify the deficiency discussed in Paragraph 3 above, regarding the maximum moment in the containment shell at the basema Since the results were taken from the center of the finite elements rather than from the top of the basemat, the reported moments did not represent the maximum values and were nonconservative in terms of structural adequacy evaluations. This lack of design verification thoroughness is considered a weakness by the NRC inspecto Review of the Narrow Gap Welding Process Members of the Materials and Processes Section staff met with Consumers Power Company personnel at the Universal Testing Laborato-ry (UTL) in Chattanooga, Tennessee, on February 6 and 7, 199 The purpose of the meeting was to familiarize NRC inspection staff with the 11 narrow-gap
welding process and to provide an opportunity for the NRC to observe a portion of the process qualificatio The 1'narrow-gap 11 process requires very precise weld groove preparation and highly specialized automatic welding equipmen This process will be
. used for the coolant loop piping welds during the Palisades steam generator replacement effor The application of this process to heavy wall nuclecr system piping will be the tirst of its kind in the United States. The process has been applied in Europe with a high degree of success and most recently at the Ringhals facility in Swede The 11 narrow-gap 11 procedure is based on the automatic Gas Tungston Arc Welding (GTAW) process with, as stated above, specialized equipment enabling the welding torch to reach deeply into a narrow weld groove preparatio To ensure a high quality weld, extreme care is required during the weld groove preparation and joint fit-up phas With respect to the actual welding process, the first 3-4 weld layers are the most critica The 11 narrow-gap 11 process is in concert vJith the ALARA concept in that the welding equipment is operated remotely and the narrow weld groove requires 10.
significantly less weld volume which results in reduced welding tim Other advantages of this process include the following:
0
0
Due to less heat input and smaller bead size, the residual stress distribution is favorabl Significant reductions in shrinkage occurs due to a decreased weld volum Low heat input and smal I bead size produce a more tavorable heat-affected zon The weld.preparation geometry provides an essentially constant, very narrow groove which does not require torch manipulation other than straight line travel. This benefit results in a reduced potential for fusion defects in the weld join *
Improved uniformity of the weld joint thereby facilitating U The NRC staff reviewed the qualification of a qualification weld being performe were also reviewed along with mechanical weld coupo process and observed a portion Radiographs of a completed weld test reports from a representative The licensee will submit a 50.59 evaluation for the cutting and welding of the coolant loop piping for NRC *revie The qualification of both the welding and UT will also be reviewed in the near futur The actual cutting and welding ot the coolant loops will be closely monitored by the NRC staf.
Exit Interview The NRC inspectors met with licensee representatives, Universal Testin~
Laboratory personnel, and Bechtel's engineering personnel as denoted in Paragraph.l during and at the conclusion of the inspections on February 7 and July 20, 1990, respectively~ The inspectors summarized the scope and results of the inspection and discussed the likely informational content of this inspection repor The licensee and their representatives acknowledged the information and did not indicate that any of the information disclosed during the inspection could be considered proprieta.ry in natur