ML20074A200

Interim Significant Const Deficiency Rept Re Mechanical Shock Arrest or Brackets Supplied by Itt Grinnell W/ Potential Interference Problems.Initially Reported on 830413.Affected Parts Returned to Itt Grinnell for Rework

ML20074A200
Person / Time
Site:	Hope Creek, 05000355
Issue date:	05/05/1983
From:	Martin Public Service Enterprise Group
To:	Allan J, Allen J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8305120384
Download: ML20074A200 (2)

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Company j Thomas J. Martin 80 Park Plaza, Newar k, NJ 07101 201-430-8316 Mailing Address: P.O. Box 570, Newark, NJ 07101 j Vi Pradet i Engineering and Construction i

l May 5, 1983 i

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i l Mr. James M. Allen, Acting Administrator U . S . Nuclear Regulatory Commission Office of Inspection and Enforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 194G6

Dear Mr. Allen:

l

SIGNIFICANT CONSTRUCTION DEFICIENCY

ITT GRINNELL SNUBBER ASSEMBLIES j HOPE CREEK GENERATING STATION i

l On April 13, 1983, a vorbal report was mode to Region I, j Office of Inspection and Enforcement representative, L. E.

Tripp, advising of a potentially significant construction deficiency concerning nonconforming dimensional conditions j of mechanical shock arrester brackets supplied by ITT j Grinnell. The following report is provided in accordance i with the requirements of 10CFR5 0.55(e ) .

Description of Deficiency Mechanical shock arrestor brackets supplied by ITT Grinnell have potential interference problems which could restrict proper operation. The affected assemblies are ITT Grinnell figures 306N and 307N in sizes 1, 3, 10, 35, and 100, manu-f actured prior to April 1980. The problem is due to over-

' size welds on rear brackets and inadequate coping of the j

pipe clamps that may preclude the ability of the snubbers to

, achieve the requisite 10* included angle cone of action to the pipe clamp axis.

In April 1980, ITT Grinnell instituted a design change to preclude this problem with their mechanical snubber brackets.

8305120384 830505 PDR S

ADDCK 05000354 pg 34 >1

Mr. James M. Allen 5/5/83 Analysis of Safety Implications As indicated in NRC IE Information Notice No. 83-20, re-ceived subsequent to our initial 10CFR50.55(e) notification, restricted motion of mechanical snubbers could lead to J

cyclic loadings that were not part of the original design stress analysis. The magnitude of such loading depends on i the amount of binding caused by the lateral loading on the snubbe r. Should it become great enough, the snubber could i be permanently damaged and possibly "f reeze" (i.e., lock permanently in one position). Depending on the snubber

position when it freezes, the piping system could experience a stress reversal when the thermal loading is removed.

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If the condition had gone undetected and uncorrected, and

the snubber locked in a " worst-case" position, stresses on 3

safety related pipe could have exceeded the design param-eters and adversely affected safe operation /shutdosn of the plant. We, therefore, consider this condition to be report-l able in accordance with 10CFR50.55(e) .

Corrective Action Bechtel Power Corporation, our Architect / Engineer and Con-structor, has performed an inspection of 350 suspect snubber assemblies in conjunction with ITT Grinnell personnel. This i inspection was concluded the week of April 18, 1983, and identified interference problems on 95 rear brackets and 80 pipe clamps. These conditions are documented in Noncon-

, formance Report Nos. 2175 and 2176.

- Since none of the snubber assemblies have been installed, the af fected components will be returned to ITT Grinnell for rework.

Very truly yours, i

I i

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! CC: Office of Inspection and Enforcement 4

Division of Reactor Construction Inspection Washington, D. C.

i NRC Resident Inspector - Hope Creek

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+ P.O. Box 241 Hancocks Bridge, NJ 08038