ML20214P735
| ML20214P735 | |
| Person / Time | |
|---|---|
| Issue date: | 11/28/1986 |
| From: | Baer R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | Randall R GRINNELL CORP. (FORMERLY ITT GRINNELL CORP.) |
| References | |
| NUDOCS 8612040336 | |
| Download: ML20214P735 (4) | |
Text
_ _ - - __ _ _ _ __ -___ - _ - _ _ _ _ _ _
160V28 N Hr. Richard T. Randall, Manager Pro' duct Engineering
. ITT Grinnell Valve Co.
Lancaster, PA
Dear Mr. 'Randall:
SUBJECT:
DRAFT INFORMATION NOTICE ON SEISMIC QUALIFICATION OF VALVES FOR COMMENT The Nuclear Regulatory Commission is in the process of preparing an information notice entitled " Inadequate Seismic Qualification of Valves by Mathematical Modeling and Analysis."
A copy of the latest draft of this information notice is enclosed for your review and comment.
Comments received by December 15, 1986, particularly those dealing with the facts presented in the ir. formation nctice, will be considered in the final revision.
Sincerely, Originalsigned by Robed L Bau Robert L. Baer, Chief Engineering and Generic Comunications Branch Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement l
Enclosure:
Draft IE IN 86-XX cc: Mr. E. Broome, ITT Grinnell DISTRIBUTION JMTaylor RWStarostecki l ELJordan SASchwartz RLBaer AWDromerick WFAnderson JGPartlow BKGrimes RHeishman GBagchi PDR 5DCSc.$ DEPER R/F EGCB R/F WAnderson R/F EGCB:DEPER:IE h&
EGCB:DEPER:IE thb9p C:TGCB:DEPER:IE WFAnderson S 7AWDromerick RLBaer 11/ff/8 11/g86 11/.7J86
, .4
SSINS No.: 6835 Ary gl IN 86-XX UNITED STATES NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 November , 1986 IE INFORMATION NOTICE NO. 86-XX: INADEQUATE SEISMIC QUALIFICATION OF VALVES BY MATHEMATICAL MODELING AND ANALYSIS Addressees:
All nuclear power reactor facilities holding an operating license or a con-struction permit.
Purpose:
This notice is provided to alert recipients to a potential problem pertaining to seismic qualification of power-operated-safety-related valves. These valves were furnished as qualified by mathematical analysis based on an inadequate model; the results of later tests showed that the actual lowest natural fre-quency of the valve may be less than that required by the purchase specification.
It is expected that recipients will review this information for applicability to their facilities and consider actions, if appropriate, to preclude a similar problem from occurring at their facilities. However, suggestions contained in this notice do not constitute NRC requirements; therefore, no specific action or written response is required.
Description of Circumstances: .
On December 27, 1984 the Dia Flow Unit of ITT Grinnell Valve Division notified purchasers of air-operated valves with extended operator structures that such valves had been determined by test to have natural frequencies less than 33 hertz. The notification was directed to nuclear power plant owners or suppli-ers who had purchased valves to specifications requiring the valves to have all natural frequencies equal to or greater than 33 hertz as demonstrated by analysis or test.
The natural frequencies of these valves had been originally determined by analysis to ensure that the valves met contract requirements. Subsequent information obtained from testing similar velves disclosed that the natural frequency of air-operated valves with extended structures is less than 33 Hz.
ITT Grinnell undertook a testing program that included fragility testing to provide data for evaluating the characteristics and capabilities of the valves.
On the basis of the fragility testing results, Grinnell drew the generic conclusion that there was not a safety problem related to valve functionality; this conclusion was presented in the December 27, 1984 notification. No notification of this problem under 10 CFR Part 21 was made at that time; however, a notification under 10 CFR Part 21 subsequently was received by the NRC from one power plant.
IN 86-XX D:cember , 1986 Page 2 of 3 g
The NRC staff reviewed the test reports obtained from ITT Grinnell and reviewed the design applications and field installations of such valves to see if they agreed that there was adequate justification for a generic conclusion that no safety problem existed. The NRC staff concluded that generic acceptance of the valves could not be determined and informed ITT Grinnell that a Part 21 notifi-cation should be issued. As a result, on October 10, 1986 ITT Grinnell issued two Part 21 notices, one for diaphragm valves with air operators on extended structures and one for diaphragm valves with limitorque operators.
The Part 21 notices point out that, in addition to valve considerations, the piping systems containing these valves and the associated piping supports also may be affected by the change in frequency and that an evaluation of the analysis methods used to qualify the valves and of the potential impact on a system may be required.
Discussion:
The natural frequencies of the valves are reflected in the mathematical model and are used for dynamic analyses of those systems requiring dynamic analysis.
Therefore, these results of dynamic analysis using the model affect predicted accelerations and forces on the valve and its operator, stresses in the piping, and forces on the pipe supports.
The test results, reported in the Part 21 notices, for valve fragility in terms of acceleration "g" levels are consistent with those that the NRC obtained from review of the ITT test report data. Although the high g levels for fragility of the valves are impressive, no generic conclusion of valve acceptability can be made because the range of specified capability in g levels, 0.15g to 4.5g, for purchase of the valves and the possibility of amplified response at fre-quencies less than 33 Hz can result in unacceptable installations. Except for cases where the valve operators are supported directly, no basis can be found for considering piping and supports to be unaffected by the change in frequency.
In the course of reviewing the possible impact of the frequency change for I these specific valves, the staff became aware of similar problems with other valves. It appears that a potential problem with the validity of valve quali-fication and piping analysis can exist for cases where valve seismic qualifi-cation was performed by analytical methods that were not confirmed by test results. This problem appears to be more common for valves that have a pre-dicted natural frequency of less than 55 Hz and that have heavy extended operators with flexibility in the interface between the valve and the operator structure.
l l
IN 86-XX D@cember , 1986 Page 3 of 3
- This infonnation is being made available to licensees to prcvide insight to a problem which may exist in systems with valves other than those specifically addressed in the Part 21 notices from ITT Grinnell. No specific action or written response is required by this information notice. If you have any questions about this matter, please contact the Regional Administrator of the appropriate regional office or this office.
Edward L. Jordan, Director Division of Emergency Preparedness and Engineering Response Office of Inspection and Enforcement Technical
Contact:
William F. Anderson, IE (301)492-4819
Attachment:
List of Recently Issued IE Information Notices 4
i