ML19225D127
| ML19225D127 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 07/06/1979 |
| From: | CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | |
| Shared Package | |
| ML19225D125 | List: |
| References | |
| PROC-790706, NUDOCS 7908070382 | |
| Download: ML19225D127 (5) | |
Text
.
TESTING / INSPECTION PROGRAM FOR PIPE SUPPORT BASEPLATES USING CONCRETE EXPANSION A!K !'OR BOLTS - BIG ROCK POINT PLANT I.
SCOPE This report describes the program which is proposed to fulfill the require-ments of USNBC IE Bulletin 79-02, REV 1, dated June 21, 1979 as applicable to the Big Rc k Point Plant. The subject bulletin requires an evaluation of the design adequacy of pipe supports associated with Seismic Category I systems as defined by USNRC Regulatory Guide 1.29, " Seismic Lesign Classifi-cation," Rev 1, dated August 1973 or as defined in the plant FHER.
More specifically, the bulletin addresses the pipe supports which use concrete expansion anchors. The program includes: The identification of the piping systems of concern, the gathering of documentation required to define the loads imposed upon the pipe supports in the system which contain concrete expansion bolts, the perfomance of any additional calculations required to determine bolt design loads for Seismic Category I systems, and the develop-cent and inplementation of field inspection, testing and repair pI scedures rasociated with pipe support baseplates or concrete expansion anchors.
II.
PROGRAM STATUS A review of pipe support detail drawings and a valkdown by area of large piping systems have been employed to deter =ine the Lamber of baseplates to be considered within the scope of the program.
The result of these efforts has been the determination that the initial construction of the Big Rock Point Plant involved a very limited use of concrete expansion anchor bolts.
The vast majority of pipe supports associated with initial construction were supported by anchors bolted into structural steel.
A number of baseplates anchored to concrete by expansion anchor bolts were also velded to structural steel.
Such baseplates, and anchor bolts, are not included within the scope of this progra=.
A single area of the plant containing regenerative heat exchanger piping has yet to be inspectca for concrete expansion anchors.
The regenerative heat exchanger piping is almost exclusively 3" and smaller piping. This area vill be inspected by July 16, 1979 and the piping vill be incorporated into the program on the same basis as the 3" and larger piping.
The vast majority of concrete expansion anchors are associated v
two plant modifications. These modifications were the addition of a redun
' core spray and a reactor depressurization system.
The addition of the redundant core spray line in 1970-1971 resulted in the installation of a significant number of pipe supports employing what are be-lieved to be Phillips Redhead shell-type expansion anchors. There are approximately ten baseplates and approximately four bolts per beneplate asso-ciated with the redundant core spray line. The redundant core spray line was not designed to any specific seismic specification. Verifiable information docu=enting the type anchor bolts and baseplates is not available.
427 180 79080 o % b $
7
2 A reactor depressurization system (RDS) was instelled at Big Rock Point in 1975-1976. The RDS was designed to meet the require =ents of the ASME Boiler and Pressura Vessel Code,Section III, Class I.
The seismic design require =ents are vell specified.
The RDS contains a significant nu=ber of Phillips vedge-type anchors.
The documentation defining the baseplates, bolt number, bolt sizes and loads applied to the plates and bolts is co=-
plete.
The RDS contains no expansion anchors other than the Phillips vedge type. The safety factor of four which has been recommended by the manu-facturer has been employed for all vedges for 3000 psi concrete.
The design analysis associated with the RDS baseplates and anchor bolts has been re-viewed in detail.
Design anchor loads for the RDS vere calculated during initial system design.
In late 1978, a significant a=ount of torque testing was perfor=ed on RDS expansion anchors inside the steam drum enclosure.
Testing, repair and re-testing was conducted until all of the wedge-type anchors met the midrange torque requirement specified by the manufacturer for the specific size bolt.
A subsequent review of the design analysis for the bolts ar.d plates indi-cates that the tested bolts meet the requirements of the subject IE bulletin with respect to the safety factor of four.
Thcrsfore, those bolts are not considered within the scope of this progra=.
It is estimated that the remaining baseplates of the RDS, those of the redun-dant core spray line and those of lines typically classified Seismic Category I but not so rated in the Big Rock Point FHSR vhich contain concrete expansion anchor bolts, nu=ber about 25 to 30.
This includes both small and large di-ameter piping. At least one anchor in each baseplate of the redundant core spray line and in the RDS will be incorporated into the progra=.
Two base-plates in the shutdown cooling heat exchanger line also vill be included.
In addition, at least one anchor in each baseplate of the small size piping noted in the future inspection of the regenerative heat exchanger roce vill also be tested.
No additional piping analyses of the redundant core spray or other piping systems whien were not designed to any specific seismic requirements will be made. Analysis of the RDS piping which may be necessary will be restricted to the pipe supports the=selves.
Any anchor which fails inspection or test-ing vill be repaired or replaced.
Testing vill be done to the design allow-able load, which is the manufecturer's stated ultimate capacity redrced by a safety factor of four. A preliminary review of pipe support design infor-mation shows that for the RDS, the design allovable load typically exceeds the bolt design load by a factor of two to five. For other nonseismically designed piping systems containing concrete expansion anchors Jhich are with-in the scope of this program, the design allovable load vill be determined based upon the inspection of the bolt (or stud) diameter and the assumption that the anchor is a Phillips product.
The factor of safety of four vill be applied for test purposes to both shell and vedge anchors, since this will result in a conservative test load.
Pullout testing, whether conducted by a calibrated torque vrench or tensioner, will be performed on at least one bolt per baseplate. The failure of a bolt dictat es testing o all other bolts in the plate of concern.
27 ie;
3 Present]f, efforts are being directed toward the procurement of pull test equip =er.t and the development of inspection testing and repair pr,ocedures.
In general, the equipment, work procedures and engineering guidelines for
+ha ppe support baseplate and concrete expansion anchor evaluation pro-gram utilized for the Palisades Plant will be applicable to the Big Rock Point Plant as well.
It is expected that inspection and tertting of the base-plates and anchor bolts will ccc=ence by August 1,1979 and that all work t.sscciated with the program vill be co=pleted and documented by Septe=ber 1, 1979 Thus, this work is expected to be complete before the end of the cur-rent outage.
III.
ENGINEING BASIS FOR PROGRAM Engineering guidelines have been established in order to determine the maxi-mum bolt loads induced by various loading conditions.
Such guidelines neces-sarily involve evaluations of baseplate flexibility with respect to direct tension and i= posed moment, shear-tension interaction on the belt, cyclic loads on the bolts and safety factors.
Anal.ysis performed to date has concluded that baseplates which have been de-signed to American Institute of Steel Construction (AISC) code stress allow-ables are of sufficient rigidity to make prying action negligible. Thus, the additional bolt load due to the bolt plate edge couple which can exist for flexible baseplates in direct tension has been evaluated and has been de ternined to be negligible.
Baseplate flexibility is judged to have a much more significant effect on bolt loads.
For rigid baseplates, the me=ent ar=
in the plane of the plate is taken from the far plate edge to the bolt center in tension.
In order to provide a conservative assessment of the tensile bolt load for flexible baseplates, the moment arm vill be considerably short-ened. For all RDS baseplates subject to induced moments, the bolt loads vill be calculated with the in-plane monent arm measured from bolt center line to the most remote point of the velded attach =ent.
Concrete expansion anchor bolts subject to tension and shear. (for RDS piping) were designed and vill be evaluated in this program based upon a linear inter-action effect. The RDS piping contains only the vedge-type anchors.
A factor of safety of four vill be applied to all test loads per manufacturer's data and reco=mendations.
For other piping systems for which complete docu=enta-tion with respect to loads and anchor type does not exist, the safety factor of four vill be employed.
A review of records and an inspection of piping systems the=selves has re-vealed that concrete expansion anchors were not e= ployed in lines subject to cyclic loads.
Seismic loads are not considered to be cyclic loads. A dynamic load factor of two vill be applied to all snubbers to account for impact loads (blowdown loads ss well as seismic loads) during the evaluation of bolt design leads.
IV.
INSPECTION, TE3 TING AND REPAIR The inspection procedures for concrete expansion anchors differ somewhat for stud (vedge) shell-type anchors.
Inspection procedures have been drafted 182
k and are being finalized.
The intent of the inspection procedures for the anchors is to implement the manufacturer's recoc=endations.
The inspec-tion equipment (ultrasonic testing equipment, electronic devices, shims and calipers) are in various stages of procurement.
The inspection of stud-type anchors will involve the following:
- Check of stud length ultrasonically.
- Verification of stud diameter.
- Check of stud projection from concrete surface.
- Check of the nut engage =ent en the etud.
- Verification of stud center-to-center and edge distance spacing per manufacturer's recommendations.
- Check of concrete surrounding the plate for indications of failure.
The inspection of shell-type anchors v'.11 involve the following:
- Verification that the shell is not in contact with the back of baseplate -
gan conductance test.
- Verification that the bolt-to-shell thread engagenent is a minimum of one bolt diameter.
- Verification of bolt diameter.
- Verification that the shoulder-to-cone reco=nendations of the manufacturer are met.
- Verification that the bolt center-to-center and edge distance spacing are per manufacturer's reco==endations.
- Check of concrete surrounding the plate for indications of failure.
The inspection of the baseplate vill include:
- A cneck of the gap between the baseplate and the concrete.
- A check to determine if any over:;ize plate holes exist.
- A record of the plate size and anchor spacing.
The testing of concrete expansion anchors is designed to determine anchor pullout capanity.
Expansion anchors vill be tested with a tensioner when-ever feasible.
The pullout test load will be greater than or equal to the design allovable load (manufacturer's ultimate capacit r divided by a factor of safety of four). Where pullout testing is not feasible, torque testing vill be e= ployed. Torque testing requirements vill be those specified by the manufacturer. The target valte for the torque test vill be the mid-range torque value for the anchor size of concern.
Prior to pullout testing, the nut or bolt vill be untightened so as to con-duct the test. Passing the pullott best implies that the anchor has been set by the initial installation terque. Therefore, the retightening of the bolt or nut need only meet certait minimum installation torque requirements.
These retightening torque requiretents vill be approximately 50 percent of the manufacturer's midrange inititi installation requirements.
427 IB3
5 Concrete expansion anchors which fail either a pullout or torque test vill be repaired or replaced. Repair may involve using vashers for stud (vedge) type anchors, grouting, redrilling or other modifications.
The replacement of anchors vill cost likely be made with Hilti-type vedges.
However, such a decision is not firm.
V.
REPORT A report. describing the results of the testing described above vill be sub-mitted to NRC Region III following completion of testing.
July 6,1979 427 184