ML16341C350
| ML16341C350 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 11/08/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7911260375 | |
| Download: ML16341C350 (20) | |
Text
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+ y**4 UNITED STATES NUCLEAR REGULATORY COMIVIISSION REGION V 1990 N. CALIFORNIABOULEVARD SUITE 202, WALNUTCREEK PLAZA WALNUTCREEK, CALIFORNIA94596 November 8, 1979 Docket Hos.
50-275 50-323 Pacific Gas and Electric Company 77 Beal e Str eet San Francisco, California 94106 Attention:
Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentlemen:
Enclosed is IE Bulletin No. 79-02, Revision 2 which requires action by you with regard to your power reactor facility(ies) with an operating license or a construction permit.
Should you have any questions regarding this.Bulletin revision or the actions required by you, please contact this office.
Sincerely, S~.~g R.
H. Engelken Director
Enclosure:
IE Bulletin No. 79-02 Revision Ho.
2 cc w/enclosure:
J. Worthington, PG8E M. Raymond, PG8E R.
- Ramsay, PG&E, Diablo Canyon
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 November 8, 1979 SSINS No.:
6820 Accession Ho.:
7908220136 IE Bulletin No. 79-02 (Revision 2)
PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS Description of Circumstances:
Inspection experiences and the review of licensee response have identified several R2 areas where the Bulletin intent has not been adequately addressed by licensees, R2 Revision No.
2 of the Bulletin is intended to clarify the intent of the Bulletin R2 and establish the NRC positions on minimum factors of safety, anchor bolt preload, R2 and the expected date of completion for certain Bulletin actions.
R2 Since the issuance of IE Bulletin No. 79-02 on March 8,
- 1979, IE inspection Rl experience and many inquiries from licensees indicate that additional informa-Rl tion and clarification is needed.
This revision is intended to serve that Rl purpose.
None of the requirements of the original Bulletin have been deleted, Rl and the due date for completion of the requested actions (July 6, 1979) has R1 not been changed.
The following text, supersedes the text of Bulletin No. 79-02.
Rl Changes from the original text are identified.,by R1 and R2 in the margin.
The Rl purpose of this revision is to identify acceptable ways of satisfying the Rl.
Bulletin requirements.
Rl While performing inservice inspections during a March-April 1978 refueling outage at Millstone Unit 1, structural failures of piping supports for safety equipment were observed by the licensee.
Subsequent licensee inspections of undamaged supports showed a large percentage of the concrete anchor bolts were not tightened proper ly.
Deficiency reports, in accordance with 10 CFR 50-55(e). filed by Long Island Lighting Company on Shoreham Unit I, indicate that design of base plates using.
rigid plate assumptions has resulted in underestimation of loads on some anchor bolts.
Initial investigation indicated that nearly fifty percent of the base plates could not be assumed to behave as rigid plates.
In addition, licensee inspection of anchor bolt installations at Shoreham has shown over fifty percent of the bolt installations to be deficient.
Vendor Inspection Audits by NRC at Architect Engineering firms have shown a wide range of design practices and installation procedures which have been employed for the use of concrete expansion anchors.
The current trends in the industry are toward more rigorous controls and verification of the installation of the bolts.
The data available on dynamic testing of the concrete expansion anchors show fatigue failures can occur at loads substantially below the bolt static capa-Rl and R2 - Identifies those additions or revisions to IE Bulletin No. 79-02
IE Bul.letin. No. 79-02 Revision 2
November 8,
1979 Page 2 of 7 cities due to material imperfections or notch type stress risers.
The data also show low cycle dynamic failures at loads below the bolt static capacities due to joint slippage.
In the review of anchor bolt installation practices, three facilities (Trojan, Duane Arnold, and Zinger) have been identified which use expansion anchor bolts in concrete block walls to attach Seismic Cateaory I piping supoorts.
Testina results of anchor bolts in concrete block walls performed at FFTF indicate signi-ficantly lower ultimate capacities than for those in concrete.
An Information llotice will be issued which provides additional details on the deficiencies identified at Trojan.
In the review of responses to the Bulletin, we have become aware that licensees may not have included review of piping supoorts with concrete expansion anchor bolts which did not use base plates.
Such supports use structural steel members (angle or channel) attached directly to the concrete by expansion anchor bolts, with the pining attached to the structural steel member.
The adequacy of the anchor holt desian and installation should be verified to satisfy the intent of the Bulletin.
R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 Action to be Taken by Licensees and Permit Holders:
This Bulletin addresses those pipe support base plates that use concrete expansion anchor bolts in Seismic Category I systems as defined by Regulatory Guide 1.29, "Seismic Oesign Classification" Revision 1, dated Auqust 1973 or as defined in the applicable FSAR.
For older plants where Seismic Category I requirements did not exist at the time of licensing it must be shown that piping supports for safety related
- systems, as defined in the Final Safety Analysis Peport, meet design reauirements.
The revision is not intended to penalize licensees who have already completed some of the Bulletin requirements.
In those instances in which a licensee has com-pleted action on a specific item and the Bulletin revision nrovides more conser-vative auidance, the licensee should explain the adequacy of the action already performed.
It should be reiterated that the purpose of the Bulletin actions are to assure operability of Seismic Category I pipina systems in the event of a seismic event.
Rl Rl Rl Rl Rl Rl Rl Rl Rl Rl Rl Rl 1.
Verify that nine support base plate flexibilitywas accounted for in the cal-culation of anchor bolt loads.
In lieu of supporting analysis justifying the assumotion of rigidity, the base plates should be considered flexible if the unstiffened distance between the member welded to the olate and the edqe of the base olate is greater than twice the thickness of the plate.
It is recognized that this criterion is conservative.
Less conservative accent-ance criteria must be justified and the justification submitted as part of the resoonse to the Bulletin. If the base plate is determined to be flexible, then recalculate the bolt loads using an appropriate analysis.
If possible, this is to be done prior to testing of anchor bolts.
These calculated bolt loads are referred to hereafter as the bolt design loads.
A description of the analytical model used to verify that pipe support base plate flexibilityis accounted for in the calculation of anchor bolt loads is to be submitted with your response to the Bulletin.
P,l Rl Rl Rl Rl
%1 Rl Rl Rl
'Revision 2
November 8, 1979 Page 3 of 7 2.
It has been noted that the schedule for analytical work on base plate flexibilityfor some facilities extends beyond the Bulletin reportino time frame of July 6, 1979.
For those facilities for which an anchor bolt testing proqram is reauired (i.e., sufficient OC documentation does not exist), the anchor bolt testing program should not be delayed.
Verify that the concrete expansion anchor bolts have the following minimum factor of safety between the bolt desiqn load and the bolt ultimate capa-city determined from static load tests (e.a.
anchor bolt manufacturer's) whhich simulate the actual conditons of installation (i.e., type of con-crete and its strength properties):
a.
Four - For wedqe and sleeve type anchor bolts, b.
Five - For shell type anchor bolts.
R1 R1 R1 Rl Rl 3.
4.
The bolt ultimate capacity should account for the effects of shear-tension R1 interaction, minimum edge distance and proper bolt soacing.
Rl If the minimum factor of safety of four for wedge type anchor bolts and R1 five for shell type anchors can not be shown then justi ication must be Rl provided.
The Bulletin factors of safety were intended for the maximum R2 support load including the SSE.
The NRC has not yet been provided adequate R2 justification that lower factors of safety are acceptable on a long term R2 basis.
Lower factors of safety are allowed on an interim basis by the R2 provisions of Supplement No.
1 to IE Bulletin Ho. 79-02.
The use of R2 reduced factors of safety in the factored load approach of ACI 349-76 has R2 not yet been accepted by the NRC.
R2 Describe the design requirements if applicable for anchor bolts to with-stand cyclic loads (e.g.
seismic loads and hiqh cycle ooerating loads).
Verify from existing OC documentation that design requirements have been met for each anchor holt in the following areas:
(a)
Cyclic loads have been considered (e.g.
anchor bolt preload is equal to or greater than bolt design load).
In the case of the shell type, assure that it is not in contact with the back of the suoport plate prior to preload testinq.
(b)
Specified design size and type is correctly installed (e.g. prooer embedment depth).
If sufficient documentation does not exist, then initiate a testinq program that wi 11 assure that minimum design reauirements have been met wi th respect to sub-items (a) and (b) above.
A samplinq technique is acceptable.
One acceptable technique is to randomly select and test one anchor bolt in each base plate (i.e.
some suoports may have more than one base plate).
The test should provide verification of sub-items (a) and (b) above.
If the test fails, all other bolts on that base plate should be similarly tested.
In any event, the test program should assure that each Seismic Category I
system will perform its intended function.
IF. Bu'll"etin No. 79-02 Revision 2
November 8, 1979 Paqe 4 of 7 The preferred test method to demonstrate the bolt preload has been accom-olished is using a direct pull (tensile test) eaual to or greater than design load.
Recognizing this method may be difficult due to accessibility in some areas an alternative test method such as torque, testing may be used.
If torque testing is used it must he shown and substantiated that a correlation between torque and tension exists.
If manu,acturer's data for the specific bolt used is not available, or is not used, then site specific data must be developed by qualification tests.
Holt test values of one-fourth (wedge type) or one-fifth (shell type) of bolt ultimate capacity may be used in lieu of individually calculated bolt design loads where the test value can be shown to be conservative.
The puroose of Bulletin No. 79-02 and this revision is to assure the operability of each seismic Category I pioing system.
In all cases an evaluation to confirm system operability must be oerformed.
If a" base plate or anchor bolt failure rate is identified at one unit of a multi-unit site which threatens operability of safety related Dipinq systems of that unit, continued operation of the remaininq units at that site must be immediately evaluated and reported to the NRC.
The evaluation must consider the generic applicability of the identified failures.
Appendix A describes two sampling methods for testing that can be used.
Other sampling methods may be used but must be justified.
Those options may be selected on a system by system basis.
Justification for omitting certain bolts from sample testing which are in high radiation areas during an outage must be based on other testing or analysis which substantiates operability of the affected system.
Holts which are found during the testing program not to be preloaded to a load equal to or greater than bolt design load must be properly pre-loaded or it must be shown that the lack of preloading is not detrimental to cyclic loading capability.
Those licensees that have not verified anchor bolt preload are not required, to go back and establish preload.
- However, additional information should be submitted which demonstrates the effects of preload on the anchor bolt ultimate capacity under dynamic loading.
If it can be established that a tension load on any of the bolts does not exist for all loading cases then no preload or testing of the bolts is required.
If anchor bolt testing is done prior to completion of the analytical work on base nlate flexibility, the bolt testing must be performed to at least the original calculated bolt load.
For testing purposes factors may be used to conservatively estimate the potential increase in the calculated bolt load due to base plate flexibility. After completion of the analytical work on the base plates the conservatism of these factors must be verified.
Rl Rl Rl R1 R1 R1 Rl R1 R1 R1 R1 Rl R1 Rl Rl R1 Rl Rl R1 R1 R1 R1 Rl R1 R1 Rl Rl R1 R2 R2 R2 R2 R1 P,1 R1 Rl R1 R1 Rl Rl Rl
IE Bulletin No. 79-02 Rqvision 2
9 t/ovember 8, 1979 Page 5 of 7 For base plate supports using expansion
- anchors, but raised from the supporting surface with grout placed under the base plate, for testina purposes it must be verified that leveling nuts were not used.
If leveling nuts were used, then they must be backed off such that they are not in contact with the base plate before applyinq tension or torque testing.
Bulletin No. 79-02 requires verification by insoection that bolts are properly installed and are of the specified size and tyoe.
Parameters which should be included are embedhent
- depth, thread engaqement, plate bolt hole size, bolt spacing, edge distance to the side of a concrete member and full expansion of the shell for shell type anchor bolts.
If piping systems 2 1/2-inch in diameter or less were computer analyzed then they must be treated the same as the larger piping. If a chart analysis method was used and this method can be shourn to be highly con-servative, then the proper installation of the base plate and anchor bolts should be verified by a sampling inspection.
The parameters inspected should include those described in the oreceding paragraph.
If small diameter oiping is not inspected, then justification of system operability must be Drovided.
Rl Rl Rl Rl Rl Rl P,l Rl Rl Rl Rl Rl Rl Rl Rl Rl Rl Rl 5.
Determine the extent that expansion anchor bolts were used in concrete block (masonry) walls to attach piping suoports in Seismic Category 1 systems (or safety related systems as defined by Revision 1 of IE Bulletin No. 79-02).
If expansion anchor bolts were used in concrete block walls:
a.
Provide a list of the systems involved, with the number of supports, type of anchor bolt, line size, and whether these supports are acces-sible during normal plant operation.
b.
Describe in detail any design consideration used to account for this type of installation.
c.
Provide a detailed evaluation of the capability of the suoports, including the anchor bolts, and 'block wall to meet the design loads.
The evaluation must describe how the allowable loads on anchor bolts in concrete block walls were determined and also what analytical method was used to determine the integrity of the block walls under the imposed loads.
Also describe the acceptance criteria, including the numerical values, used to perform this evaluation.
Review the deficien-cies identi,ied in the Information Notice on the pipe supports and walls at Trojan to determine if a similar situation exists at.your facility with regard to supports using anchor bolts in concrete block walls.
d.
Describe the results of testina of anchor bolts in concrete block walls and your plans and schedule for any further action.
6.
Determine the extent that oipe suooorts with exoansion anchor bolts used structural steel shapes instead of base plates.
The systems and lines R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2
IE Bulletin Ho. 79-02 Revision 2
November 8, 1979 Page 6 of 7 7.
8.
9.
reviewed must be consistent with the criteria of IE Bulletin No. 79-02, Revision l. If expansion anchor bolts were used as described above, verify that the anchor bolt and structural steel shapes in these supports were included in the actions performed for the Bulletin. If these suoports cannot be verified to have been included in the Bulletin actions:
a.
Provide a list of the systems involved, with the number of suoports, type of anchor bolt, line size, and whether the supports are acces-sible during normal plant operation.'.
Provide a detailed evaluation of the adequacy of the anchor bolt design and installation.
The evaluation should address the assumed distribu-tion of loads on the anchor bolts.
The evaluation can be based on the results of previous anchor bolt testing and/or analysis which substantiates operability of the affected system.
c.
Describe your plans and schedule for any further action necessary to assure the affected systems meet Technical Specifications operability requirements in the event of an SSF..
For those licensees that have had no extended outages to perform the testinq of the inaccessible anchor bolts, the testing of anchor bolts in acces-sible areas is expected to be completed by November 15, 1979.
The testing of the inaccessible anchor bolts should be completed by the next extended outage.
For those licensees that have completed the anchor bolt testing in inaccessible
- areas, the testing in accessible areas should continue as raoidly as possible, but no lonqer than March 1, 1980.
The analy'sis for the Bulletin items covering base plate flexibilityand factors of safety should be completed by November 15, 1979.
Provide a schedule that details the completion dates for IE Bulletin No. 79-02, Revision 2, items 1, 2, and 4.
tlaintain documentation of any sampling inspection of anchor bolts required by item 4 on site and available for NRC inspection.
All holders of operatinq licenses for power reactor facilities are requested to, complete items 5, 6, and 7 within 30 days of the date of issuance of Revision No. 2.
Also describe any instances not previously reported, in which you did not meet the revised (R2) sections of items 2 and 4 and, if necessary, your plans and schedule for resolution.
Report in writing within 30 days of the date of this revision issuance, to the Director of the appropriate Regional Office, completion of your review.
For action not yet complete, a final renort is to be submitted upon completion of your action.
A copy of your report(s) should be sent to the United States Nuclear Regulatory Comnission, Office of Inspection and Enforcement, Division of Reactor Operations Inspection, ktashington, D.C.
20555.
These reportina require-ments do not oreclude nor substitute for the aoplicable requirements to reoort as set forth in the regulations and license.
All holders of construction nermits for power reactor facilities are r equest-ed to comolete items 5 and 6 for installed nipe supports within 60 days of date of issuance of Revision Ho. 2.
For pipe sunports which have not yet R2 R2 R2 P.2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2.
R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 R2 Rl Pl P,l P,l Rl R2 R2 R2
IE Bulletin No. 79-02 Revision 2
November 8, 1979 Page 7 of 7 been installed, document your action to assure that items 1 through 6 will R2 be satisified.
Maintain documentation of these actions on site available R2 for NRC inspection.
Report in writing within 60 days of date of issuance of R2 Revision No. 2, to the Director of the aopropriate NRC Regional Office, corn-R2 pletion of your review and describe any instances not previously reported, R2 in which you did not meet the revised (R2) sections of items 2 and 4 and, if R2 necessary, your plans and schedule for resolution.
A copy of your report R2 should be sent to the United States Nuclear Pegulatory Commission, Office R2 of Inspection and Enforcement, Division of Reactor Construction Inspection, R2 Hashington, D.C.
20555.
R2 Anproved by GAO (P0072); clearance expires 7/31/80.
Approval was qiven under a
blanket clearance specifically for identified generic problems.
Enclosures:
l.
Apoendix A 2.
Recently Issued IE Bulletins R1
APPENDIX P SAMPLING METHODS Item 4 of this Bulletin states that for anchor bolt testing purposes a samoling orogram is acceptable.
Two sampling methods are discussed below, but other methods may be used if justified.
a.
Test one bolt on each plate as originally recommended in Bulletin No. 79-02.
If the test fails, all other bolts on that base plate should be similarly tested.
A high failure rate should be the basis for increased testing.
b.
Randomly select and test a statistical sample of the bolts to provide a 95 percent confidence level that less than 5 percent defective anchors are installed in any one seismic Category I system.
The sampling p~ogram should be done on a system by system basis.
9 IE Bul'htin No. 79-02, Revision 2
Novebmer 8, 1979 RECENTLY ISSUFO IE BULLETINS 4
Enclosure Bulletin No.
Subject Date Issued Issued To 79-25 Failures of Westinghouse 11/2/79 BFD Relays In Safety-Related Systems All power reactor facilities with an OL or CP 79-24 79-23 Frozen Lines Potential Failure of Emergency Diesel Generator Field Exciter Transformer 9/27/79 9/12/79 All power reactor facilities which have either OLs or CPs and are in the late stage of construction All Power Reactor Facilities with an Operating License or a construction permit 79-14 Seismic Analyses For (Supplement
- 2) As-Built Safety-Related Piping Systems 9/7/79 All Power Peactor Facilities with an OL or a CP 79-22 Possible Leakage of Tubes 9/5/79 of Tritium Gas in Time-pieces for Luminosity To Each Licensee who Receives Tubes of Tritium Gas Used in Timepieces for Luminosity 79-13 (Rev.
1)
Cracking in Feedwater System Piping 79-02 Pipe Support Base Plate (Rev.
1)
Oesigns Using Concrete (Supplement
- 1) Expansion Anchor Bolts 8/30/79 8/20/79 All Oesignated Applicants for OLs All power Reactor Facilities with an OL or a CP 79-14 (Supolement) 79-21 79-20 Seismic Analyses For As-Built Safety-Rel ated Piping Systems Temperature Effects on Level ~leasurements Packaging Low-Level Radioactive Maste for Transport and Burial 8/15/79 8/13/79 8/10/79 All Power Reactor Facilities with an OL or a CP All Pl<Rs with an operating license All Haterials Licensees who did not receive Bulletin l'lo. 79-19
v