Difference between revisions of "ML20071N940"
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ILLINOIS POWER CO.
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
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ILLINDIS POWER COMPANY 1000~L
[)CI U-10058 CLINTON POWER STATION. P.O. 80x 678. CLINTON. ILLINOIS 61727 May 31, 1983 Docket No. 50-461 Mr. James G. Keppler Regional Administrator Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137
Potential Deficiency 82-12 10CFR50. 55 (e)
Binding of Sway Strut / Snubber Piping Component Supports
Dear Mr. Keppler:
On October 21, 1982, Illinois Power notified Mr. H. Wescott, NRC Region III, (Ref: IP memorandum Y-13998, 1605-L, dated October 21, 1982) of a potentially reportable deficiency per 10CFR50.55(e) concerning the fabrication of sway strut type pipe supports. The location of welds on the eyelet of the sway strut interferes with the retaining bracket (clevis) such that the required motion of the sway strut may not be achieved. This initial notification was followed by two (2) interim reports (Ref: IP letter U-100ll, D. P. Hall to J. G. Keppler dated November 20, 1982, 1605-L, and IP letter U-10032, D. P. Hall to J. G. Keppler dated February 18, 1983, 1605-L). Our investiga-tion into this matter continues, and this letter represents an interim report per 10CFR50.55(e).
Statement of Potentially Reportable Deficiency The welded male rod extension piece used in sway strut and snubber piping supports supplied by Basic Engineers (BE) binds in the pipe clamp and rear bracket, limiting the designed range of motion. The binding could cause extra loads on the weld attach-ing the rear bracket (clevis) to the structure. This additional load could result in failure of the weld. Further investigation is necessary to determine the extent and significance of this concern, and to evaluate what actions are required to correct this potentially reportable deficiency.
Background / Investigation Results During inspection activities of piping support installation a by Baldwin Associates (IP Contractor) , a sway strut type pipe support was found where metal to metal contact existed between f$ 31
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' J. G. Keppler May 31, 1983 NRC the male rod extension piece and the pipe clamp. This condition does not conform with Baldwin Associates Procedure BAP 3.2.5-(Piping Component Supports), which requires the piece to pivot in all directions without binding. . A Deviation Report (DR-3382) was
initiated to document this occurrence. Further investigation found that these male rod extension piecas are also used on sway strut type supports to connect to-the rer.r bracket (clevis), and therefore binding could also occur at this location. This concern was. confirmed by a random inspection of installed sway strut supports which identified several interferences. Addition-ally, some mechanical snubbers utilize similar male rod extension pieces and could be subject to binding.
i The problem was further investigated by the piping support supplier, Basic Engineers. Their investigation found that the interferences were due to accumulative fabrication tolerances
- given on BE's data sheets for these types of supports. Investi-
- gation by Baldwin Associates determined that, in some cases,
, overwelding of the eyelet to the threaded rod of the male rod extension piece also contributed to the interference.
In order to determine the scope of this problem on installed hardware, a two-phased inspection program has been implemented at Clinton Power Station (CPS). This inspection program utilizes 4 personnel employed by Basic Engineers on site to measure the clearances available and the critical dimensions for installed i
sway struts anc snubbers. Using the actual dimensions for each installation, the available freedom of movement will be calculat-ed. Upon. completion cc the inspection effort and after actual
~i freedom of movement is calculated, a course of action can be determined for each support.
Investigation has also determined that supports could exist which appear bound in the cold condition,.yet adequate clearance may be available due to movement of the hanger resulting from thermal growth of the pi e. Sargent & Lundy (CPS Architect-Engi-l
, neer) denign standards a low the pipe-support joint to move 4 i within 2 ' without design compensation. However, in cases where large thermal movements or short struts are involved, design compensations, such as offsetting the attachments to the pipe and structure, may have been made to accommodate this movement such that the support in its cold setting may appear bound. A list of affected supports with offset attachments has been compiled by Basic Engineers using Sargent & Lundy design drawings, and specific inspection criteria for these supports will be devel-oped.
i Corrective Action (Interim) l i
Although investigation of this potential deficiency is still in process, several actions have been or are being taken to identify and correct the problems, and to prevent recurrence:
- 1. Baldwin Associates stopped issuing welded male rod extension pieces (BE part Nos. 415-1 and 411-2) to the
J. G. Keppler May 31, 1983 NRC field and fabrication shops until after an inspection of hanger parts had been performed in each building's lay down area. Defective parts were tagged and segregated to prevent inadvertent use or installation.
- 2. Baldwin Associates Quality Assurance intensified its surveillance of Basic Engineers' fabrication activities at BE's shops and at CPS.
- 3. Baldwin Associates Quality Control has revised the criteria for their installation inspection program to include binding checks. Additionally, Quality Control Instruction QCI-300, Inspection of Piping Component Supports, has been revised and issued to include detailed instructions for mcking the binding check.
Training was provided to Quality Control inspectors on this matter on May 13, 1983.
- 4. Basic Engineers has supplied Baldwin Associates Quality Control with feeler gauges to implement the binding check detailed in QCI-300. The gauges will be cali-brated in accordance with applicable procedures.
- 5. Sargent & Lundy drawing M09-1001N was revised to clarify installation tolerances with regard to pipe support.
- 6. A field inspection of installed sway struts and snub-bers supplied by Basic Engineers is being performed by l
BE employees to determine the number of supports affected by problems of inadequate clearance and the l amount of clearance available for each support. BE's l shop inspection procedure was revised by BE to address their field inspection activities at CPS. The method of measurement for interferences has been prequalified on a shop mock-up to ensure its validity.
- 7. Upon completion of the field inspection effort, the j scope of this problem will be better defined, and a decision can be made on remedial action necessary to correct identified deficiencies. This action may include an engineering analysis of the deficiencies and/or a parts replacement / rework program.
Safety Implications / Significance Until the inspection effort described above is completed and i the scope of this potential deficiency is defined, it is not l possible to assess the safety implications and significance of I
this concern. Additionally, the extent of action necessary to correct identified deficiencies through rework / replacement of parts or engineering analysis cannot be determined until the scope of this potential deficiency is defined. It is anticipated l that approximately ninety (90) days will be necessary to file a l final report on this subject.
J. G. K:ppler May 31, 1983 NRC We trust that this interim report provides sufficient background information to perform a general assessment of this potentially reportable deficiency and adequately describes our overall approach to resolve the problem.
Sincerely yours ,
D. P. Hall Vice President REC /jf cc: Director, Office of I&E, U.S. NRC, Washington, DC 20555 Illinois Department of Nuclear Safety NRC Resident Inspector Manager-Quality Assurance INPO Records Center l