ML19296A466
| ML19296A466 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/08/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Groce R VERMONT YANKEE NUCLEAR POWER CORP. |
| References | |
| NUDOCS 7903280001 | |
| Download: ML19296A466 (1) | |
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, The enclosed 1E Bulletin. 'No.17'9'-02' is fonvarded to you for action.
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'll. ~ IE Bulletin No. 79 '02 -.
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W. ' F..Co'nway,.!'Pl' ant Sup,erintendent S. D. Karpyak,' Manager, Administrative and Technical Liaison A. Z..Roisman,' Natural Resources Defense Council 790328O60
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Bulletin No. 79-02 Date: March 8, 1979 Page 1 of 3 PIPS CUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS Description of Circumstances:
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 undamagd supports showed a large percentage of the concrete anchor bolts were not tightened properly.
Deficiency reports, in accordance with 10 CFR 50.55(e), filed by Long Island Lighting Company on Shoreham, 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 cauld 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 capacities 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.
Action to be Taken by Licensees and Permit Holders:
For pipe support base plates that use concrete expansion anchor bolts in Seismic Category I systems as defined by Regulatory Guide 1.29, " Seismic Design Classification" Revision 1, dated August 1973 or as defined in the applicable FSAR.
1.
Verify that pipe support base plate flexibility was accounted for in the calculation of anchor bolt loads.
In lieu of supporting analysis justifying the assumption of rigidity, the base plates
IE Bulletin No. 79-02 Date:
March 8, 1979 Page 2 of 3 should be considered flexible if the unstiffened distance between the member welded to the plate and the edge of the base plate is greater than twice the thickness of the plate.
If the base plate is detennined to be flexible, then recalculate the bolt loads using an appropriate analysis which will account for the effects of shear - tension interaction, minimum edge distance and proper bolt spacing. This is to be done prior to testing of anchor bolts.
These calculated bolt loads are referred to hereafter as the bolt design loads.
2.
Verify that the concrete e.<pansion anchor bolts have the following minimum factor of safety between the bolt design load and the bolt ultimate capacity determined from static load tests (e.g. anchor bolt manufacturer's) which simulate the actual conditions of installation (i.e., type of concrete and its strength properties):
a.
Four - For wedge and sleeve type anchor bolts, b.
Five - For shell type anchor bolts.
3.
Describe the design requirements if applicable for anchor bolts to withstand cyclic loads (e.g. seismic loads and high cycle operating loads).
4.
Verify from existing OC documentation that design requirements have been met for each anchor bolt 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 support plate prior to preload testing.
(b)
Specified design size and type is correctly installed (e.g. proper embedmentdepth).
If sufficient documentation does not exist, then initiate a testing program that will assure that minimum desi met with respect to sub-items (a) and (b) gn requirements have been above. A sampling technique is acceptable. One acceptable technique is to randomly select and test one anchor bolt in each base plate (i.e. some supports mey have more than one base plate). The test should provide verificatien of sub-items (a) and (b) above.
If the test fails, all other bolts on t:1at base plate should be similarly tested.
In any event, the test program should assure that each Seismic Category 1 system will perform its intended function.
IE Bulletin No. 79-02 Date: March 8, 1979 Page 3 of 3 5.
All holders of operate..g licenses for power reactor facilities are requested to complete items 1 through 4 within 120 days of date of issuance of this Bulletin. A reactor shutdown is not required to be initiated solely for purposes of this inspection above. Maintain documentation of any sampling inspection of anchor bolts required by item 4 on site and available for NRC inspection.
Report in writing within 120 days of date of Bulletin issuance, to the Director of the appropriate NRC Regional Office, completion of your verifica-tion and describe any discrepancies in meeting items 1 through 4 and, if necessary, your plans and schedule for resolution.
For planned action, a final report is to be submitted upon completion of your action. A copy of your report (s) should be sent to the United States Nuclear Regulatory Comission, Office of Inspection and Enforcement, Division of Reactor Operations Inspection, Washington, D.C.
20555. These reporting requirements do not preclude nor substitute for the applicable requirements to report as set forth in the regulations and license.
6.
All holders of construction pennits for power reactor facilities are requested to complete items 1 though 4 for installed pipe support base plates with concrete anchor bolts within 120 days of date of issuance of this Bulletin.
For pipe support base plates which have not yet been installed, document your actions to assure that items 1 though 4 will be satisfied. Maintain documentation of these actions on site and available for NRC inspection.
Report in writing within 120 days of date of Bulletin issuance, to the Director of the appropriate NRC Regional Office, completion of your review and describe any discrepancies in meeting items 1 though 4 and, if necessary, your plans and schedule for resolution.
A copy of your report should be sent to the United States Nuclear Regulatory Comission, Office of Inspection and Enforcement, Division of Reactor Construction Inspection, Washington, D.C.
20555.
Approved by GA0 B180225 (R0072); clearance expires 7/31/80.
Approval was given under a blanket clearance specifically for identified generic problems.
Enclosure:
IE Bulletins Issued in Last Twelve Months
IE Bulletin No. 79-02 Date: March 8, 1979 Page 1 of 2 LISTING 0F IE BULLETINS ISSUED IN LAST TWELVE MONTHS Bulletin Subject Date Issued Issued To No.
78-05 Malfunctioning of 4/14/78 All Power Reactor Circuit Breaker Facilities with an Auxiliary Contact Operating License Mechanism - General (0L) or Construction Electric Model CR105X Permit (CP) 78-06 Defective Cutler-5/31/78 All Power Reactor Hammer, Type M Relays Facilities with an With DC Coils OL or CP 78-07 Protection afforded 6/12/78 All Power Reactor by Air-Line Respirators Facilities with an and Supplied-Air Hoods OL, all class E and F Research Reactors with an OL, all Fuel Cycle FacilitiE; with an OL, and all Priority I Material Licensees 78-08 Radiation Levels from 6/12/78 All Power, Test and Fuel Element Transfer Research Reactor Tubes Facilities with an OL having Fuel Element Transfer Tubes 78-09 BWR Drywell Leakage 6/14/78 All BWR Power Paths Associated with Reactor Facilities Inadequate Drywell with an OL (for action)
Closures or CP (for information) 78-10 Bergen-Paterson 6/27/78 All BWR Power Reactor Hydraulic Shock Facilities with Suppressor Accumulator an OL or CP Spring Coils
IE Bulletin No. 79-02 Date: March 8, 1979 Page 2 of 2 LISTING 0F IE BULLETINS ISSUED IN LAST TWELVE MONTHS (CONTINUED)
Bulletin Subject Date Issued Issued To No.
78-11 Examination of Mark I 7/24/78 BWR Power Reactor Containment Torus Facilities with an OL Welds for action:
Peach Bottom 2 and 3, Quad Cities 1 and 2, Hatch 1, Monti-cello and Vermont Yankee.
All other BWR Power Reactor Facilities with an OL for information 78-12 Atypical Weld Material 9/29/78 All Power Reactor in Reactor Pressure Facilities with an Vessel Welds OL or CP 78-12A Atypical Weld Material 11/24/78 All Power Reactor in Reactor Pressure Facilities with an Vessel Welds OL or CP 78-13 Failures In Source Heads 10/27/78 All General and of Kay-Ray, Inc., Gauges Specific Licensees Models 7050, 70508, 7051, with the subject 70518, 7060, 70608, 7061 Kay-Ray, Inc.
and 7061B Gauges 78-14 Deterioration of Buna-N 12/19/78 All BWR Power Reactor' Components In ASCO Facilities with an OL Solenoids (for action), and all other Power Reactor Facilities with an OL or CP (for inforination) 79-01 Environmental Qualifica-2/8/79 111 Power Reactor tion of Class IE Equipment Facilities with an OL, except the 11 Systematic Evaluation Program Plants (for action), and all other Power Reactor Facilities with an OL or CP (for in-formation)