ML20059B972

Forwards Reactor Head & Upper Shell Insp Plan,Per 900419 Meeting.Insp Plan Does Not Encompass Uppermost shell-to- Shell Weld Due to Technological Limitations

ML20059B972
Person / Time
Site:	Quad Cities
Issue date:	08/28/1990
From:	Stols R COMMONWEALTH EDISON CO.
To:	Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
NUDOCS 9008300198
Download: ML20059B972 (3)

Text

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' August 28,1990 Dr. Thomas E. Murley

- Office of Nuclear Reactor Regulation U.S. Nuclear Repdatory Commission Washington, D.G. 20555 ATTN: Document Control Desk Subjecu Quad Cities Nuclear Station Unit 1 Reactor Head and Upper Shell Ins ection Plan l NR pskeLHoJHE254 i

References:

(a) R. Stols to T.E. Murley letter dated L May 4,1990. -

(b) R. Stols to T.E. Murley letter dated August 27,1990.

Dr. Murley: 7 On Apri' 19,1990, members of the Nuclear Reactor Regulation's (NRR) and Commonwealth Edison Com muy's staff conducted a technical meeting to discuss the cracks identified in We Quac Cities Unit 2 Reactor Vessel Head. Durmg that 1 meeting, Commonwealth Edison committed to perform inspections of the reactor vessel head at each ofits Boiling Water Reactors (BWR) Plants.

Reference (a) provided the schedule for submitting various information to the'NRC. In reference (n), Conunonwealth Edison committed to review the fabrication records for the upper vessel structure in order to identify target areae for inspection. A summary of a hmited number of fabrication records for Quad Cities UmL 1 upper vessel was provided in reference (b).

Attached for your staff's review is the Reactor Head and Upper Shell Inspection Plan for Quad Cities Unit 1. The Quad Cities 1 fabrication history review revealed that major mismatches with manual back cini(similar to Quad Cities Unit

2) had occurred at the head-to-flange, shell to-flange and uppermost shell-to-shell welds duriug the fabrication process. The inspection, therefore, will concentrate on the head-to-flange and shell-to-flange welds areas; however, the inspection plan also encompasses the remainder of the reactor head to verify that cracking is not occurrmg in other areas. The Inspection Plan will be implemented during the upcoming Unit 1 Refueling Outage currently scheduled to begin November 12,1990.

The plan delineates that visual examinations be performed for the reactor head to-flange and vessel shell to-flange welds to identify any evidence of potential  !

cracks. The mepection plan requires that indication be further examined by ultrasonic examination. The liquid penetration examination for indications on the vessel shell to flang'e weld is optional, due to radiation exposure considerations.

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Dr. T.E. Murley August 28,1990 The Inspection Plan does not encom. pass the uppermost shell-to-shell weld due to technologicallimitations. Remote automated ultrasonic examination ..

y for BWR vessel welds is underway; however, the technology cannot be technolog;eliably utilized t at this time. Examination of the uppermost shell-to-shell cannot be achieved by examination of the outer diameter due to inaccessibility, and manual liquid penetrant anul/or manual ultrasonic examination from the inner diameter-cannot be accomalished due to the radiation doses anticipated at that area.

Commonwealth "Sdison, however, will perform the inspections when the technology is better developed.

If there are any questions or comments, please direct them to me at (708) 515 7283.

Very truly yours, i.

Rita Stols Nuclear Licensing Administrator cc: A.B. Davis, Regional Administrator (RIII)

L.N. Olshan, Project Manager (NRR)

U. Elliot, Technical Staff (NRR)

T. Taylor, Senior Resident Inspectm. Quad Cities ,

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. PROPOSED REACTOR READ AND UPPER SHELL INSPECTION PLAN (QUAD CITIES UNIT 1)

REACTOR HEAD

1. ~ Direct visual examination, V71, of.100% ID of the reactor head.

Lighting adequacy must be verified with a 1/32 inch black line on a 18% neutral gray card.

Conditions to be examined for and recorded:

a/. Cracks or linear indications b/. Heavy / unusual rust streaks c/. Clad repair and/or clad thickness variations

'd/. Excessive grinding

2. Photograph representative areas of the ID of the reactor head.

3.- Dye penetrant test (PT) the following:

a/. All linear indications

.b/. All-heavy / unusual rust streaks c/. Sample of clad repair and/or- clad thickness variation areas as determined by CECO Nuclear Engineering Department (NED).

d/. ' Sample of excessive grinding areas as determined by NED.

4. Ultrasonically test (UT), from the ID, all cracks detected by VT and/or PT.

VESSEL SHE1J,-TO-PLANGE WELD

-1. Direct visual examination, VT-1, the ID_of the weld (360*~ band of 15" wide). Remote visual examinatian is also acceptable.

Lighting adequacy must be verified w; a a 1/32 inch black line on a 18% neutral gray card. The remote ex mination system,;if used~, must be capable of-resolving a 0.001 inch wire.

Conditions to be examined for and recorded:

a/. Cracks or linear indications b/. Heavy / unusual rust streak '

c/. Clad repair and/or clad thickness variations d/. Excessive grinding

2. PT all linear indications, if desired for crack confirmation.

3. UT from the ID, diractly or remotely:

- all cracks detected by VT, and all linear indications detected by VT which are confirmed to be cracks by PT.

or

- all' linear indications detected by VT if PT is not performed.

12MAINT/311 ,