IR 05000341/1987019

Insp Rept 50-341/87-19 on 870428-29.No Violations or Deviations Noted.Major Areas Inspected:Mods to Main Steam Instrument Taps to Prevent Weld Cracking

ML20215K301
Person / Time
Site:	Fermi
Issue date:	05/05/1987
From:	Danielson D, Yin I NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20215K290	List: IR 05000341/1987019 ML20215K288
References
50-341-87-19, NUDOCS 8705110145
Download: ML20215K301 (4)

Text

. _ - - _ _ - _ _ _

.

'.

U. S. NUCLEAR REGULATORY COMMISSION

REGION III

Report No.: 50-341/87019(DRS)

Docket No.: 50-341 License No. NPF-43 Licensee: The Detroit Edison Company 2000 Second Avenue Detroit, MI 48226 Facility Narre: Fermi 2 Inspection At: Fermi 2 Site, Newport, MI Inspection Conducted: April 28-29,1987 at the site M712 bet Nevs Inspector I. T. Yin 6//# #2 0877/kad!/ws Approved By: D. H. Danielson, Chief SI7 Materials and Processes Date Section Inspection Summary Inspection on April 28-29, 1987 (Report No. 50-341/87019(DRS))

Areas Inspected: Special, announced inspection of modifications to the main steam instrument taps to prevent weld cracking. (92705)

Resul ts: Of the areas inspected, no violations or deviations were identifie l l

l l

i

)

870S110145 07050S j PDR ADOCK 05000341 <

G PDR i

. . -. - - - . - . _

.

'

.

DETAILS Persons Contacted

.

Detroit Edison Company (DECO)

i

• B. R. Sylvia, Group Vice President

* S. Orser. Vice President, Nuclear Engineering (NE)

• F. E. Agosti, Vice President, Nuclear Operations

! L. J. Simpkin, Director, NE C. R. Gelletly, General Supervisor, P&PE, NE L. C. Fron, Supervisor, NE

, M. S. Williams, Senior Engineer, NE J R. L. Tassell, I&C Engineer, NE T. Randazzo, Director, Regulatory Affairs t

S. R. Frost, Licensing Staff

F. H. Sondgeroth, Senior Licensing Engineer L. J. Grant, Lead EQA Engineer

]

Sargent and Lundy Engineers

,

D. E. Olson, Supervisor Hopper and Associates i

'

D. M. Hopper, President U. S. Nuclear Regulatory Commission (NRC)

.

M. E. Parker, Resident Inspector A. Lee, Mechanical Engineer, NRR (EMEB)

. * Denotes some of those present at the exit meeting conducted at the

! site on April 29, 198 . Main Steam (MS) Instrument Tap Steam Leaks i On January 6,1987, six leaks were found at various locations on the MS line. DECO redesigns / corrective actions to eliminate the problem were presented to the NRC on January 21, 1987, at the Region III office.

i On April 4,1987, four leaks were again found at various locations on the MS line including the MS by-pass line and between the manifold and the HP turbine. The cracked welds were attributed to flow induced vibration that j was caused by heavy throttling of valves, possible design deficiencies, and errors in the analysis of data.

!

> There are a total of 134 MS instrument taps located at by-pass valves, stop valves, throttle valves, turbine nozzles, manifolds, flanges and,

piping connecting these components. The DECO evaluation and corrective l action on these leaks are as follows

'

i i

,

.

w, - , - -,,9.r..-------,..--r.-r -.4 .,-y,,p. .+ . -- . - ,,,am,,.y . -

. . , . , - , . , , , - . . - . - - - ,_v--.e--- . , , _ ,y,.,, , . ,- , - - , . - ., ,. -v -,,,w-,

.

.

. Minimum or No Modification

• 34 flange leak detection connections were modified by reducing nipple lengths and/or upgrading to Schedule 160 nipple flange leak detection connections were modified at the socket joints to incorporate a t x 2t weld configuratio flange leak detection connections were evaluated to be acceptable, no modification was required, ModjficationbyPluggingtheTaps e

• V? taps were screw plugged and seal welde active and 12 inactive taps were modified by removal of the valves, shortening connections, and welding of a plug or a cap at the en Nozzle Modification Sixteen drain connection attachments to the valve bodies or turbine casings were replaced with new configurated fittings that will improve the stress distribution at the nozzle are Modification by Removal of Stress Riser Eight taps received major analytical evaluation including finite element analysis for the failed and modified configurations. The fixes included removal of notch configurations created at welds to valves, replacement of the valve with a lighter weight valve, and installation of a f exible hose on the valve discharg Modification by Removal of Dissimilar Metal Welds Thirty-one tap welds were modified to remove the dissimilar metal welds. The stainless steel valves were replaced by carbon steel valves. The connection configurations was also improve No items of violations or deviations were identifie . NRC Inspection of the MS Instrument Tap Modifications On April 28-29, 1987, the NRC inspection team observed representative samples of all the modifications and repairs incorporated for the MS instrument taps, and considered them to be significantly improved configurations in terms of structural fatigue design. The analytical data was evaluated by NRR and found to be acceptable. The NRC inspection team found additional assurance in the revised designs and modification No items of violations or deviations were identifie .. ._

.

.

.

4. Exit Intervie,w The Region III inspector and the NRR staff met with licensee representatives (denoted in Paragraph 1) at the conclusion of the inspection on April 29, 1987. The inspectors summarized the scope and findings of the inspection. The inspectors also discussed the likely informational content of the inspection report with regard to documents or processes reviewed b the inspector during the inspection. The licensee representatives did not identify any such documents / processes as proprietar >

4