IR 05000455/1986027

Insp Rept 50-455/86-27 on 860819 & 20.No Noncompliance Noted.Major Areas Inspected:Procedures,Specs & Results of Facility Structural Integrity Test of Containment Structure

ML20209F053
Person / Time
Site:	Byron
Issue date:	09/05/1986
From:	Danielson D, Norton F NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
Shared Package
ML20209F048	List: IR 05000455/1986027 ML20209F041
References
50-455-86-27, NUDOCS 8609120033
Download: ML20209F053 (5)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION III

Report No. 50-455/86027(DRS)

Docket No. 50-455 License No. CPPR-131 Licensee:

Commonwealth Edison Company Post Office Box 767 Chicago, IL 60690 Facility Name:

Byron Station, Unit 2 Inspection At:

Byron Site, Byron, IL Inspection Conducted: August 19 and 20, 1986 Wh e Inspector:

F. Norton

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Date b

Approved By:

D. H. Danielson, Chief Materials and Processes Section Date Inspection Summary Inspection on August 19 and 20, 1986 (Report No. 50-455/86027(DRS))

Areas Inspected:

Routine announced inspection of procedures, specifications, and results of the Unit 2 structural integrity test of the containment structure.

Results:

No items of noncompliance were identified.

8609120033 860705

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PDR ADOCK 0500

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DETAILS 1.

Persons Contacted Commonwealth Edison Company (Ceco)

• E. Martin, Quality Assurance Superintendent

• R. Klingler, Project Quality Control Supervisor

• R. Guse, Structural Engineer

• E. Briette, Quality Assurance Engineer U.S. Nuclear Regulatory Commission J. Hinds Jr., Senior Resident Inspector

• P. Brochman, Resident Inspector

• Denotes those who attended the exit interview.

2.

Containment Structural Integrity Test - Unit 2 This inspection addressed the structural integrity test performed on the Unit 2 containment structure.

Test procedures, specifications, quality records, and test results were reviewed.

a.

General The Unit 2 structural integrity testing pressurization was commenced at 0800 on May 23, 1985, and depressurization to 0.0 psig was accomplished at 0700 on May 25, 1985. The engineering firm of Wiss, Janney, Elstner Associates, Incorporated (WJE) of Northbrook, Illinois was retained by Commonwealth Edison Company to install the prescribed instrumentation, monitor the response of the instruments, conduct crack surveys prior to and during the testing, and report on the results.

The location of test instrumentation was planned by Sargent & Lundy Engineers, Chicago, Illinois.

The work was conducted in accordance with Sargent & Lundy Specification No. F/L-2922.

All installations were performed or supervised by WJE personnel.

That part of the work normal to their skills (routine installation of electrical lead wire, etc.), was performed by tradesmen.

b.

Objective of the Structural Testing The instrumentation and subsequent structural integrity test was performed to accomplish the following:

Measure and record the structural response of the primary

containment under design pressure loading to 50 psig.

Verify that the measured response fell within the predicted

design limitations and tolerances.

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Demonstrate that the structural integrity of the primary

containment structure is maintained under the 1.15 times design internal pressure load.

-c.

Pretest and Post Test Examination Prior to and following the structural integrity test, accessible portions of the exterior structure were surveyed for cracks.

Accessible portions of the liner were surveyed to detect excessive deformation.

Observations were made from all accessible walkways, floors, roofs, and available scaffolding.

In addition to the over -

all inspection, ten areas were chosen for detailed crack monitoring during the test.

Each area measured approximately 49 square feet.

Crack widths observed prior to, during, and after the pressurization were measured using 6X comparators.

The crack widths were recorded only if they exceeded 0.01 inch.

d.

Displacements Gross deformation measurements were obtained at the following nominal levels:

0, 10, 20, 30, 40, 50, 57.5, 50, 40, 30, 20, 10, and-0 psig.

At each pressure increment, pressurization /

depressurization was halted for one hour before data was obtained.

These data were immediately reduced and printed out.

The printout was reviewed by the attending Sargent & Lundy engineer prior to continuing to pressurize'or depressurize to the next increment.

At each specified pressure level, a series of deflection measurements were made at selected locations as outlined below:

Radial displacements of the cylinder on four azimuths at four

elevations between the base slab and dome springline and at dome to cylinder transitions.

Radial displacements of the containment wall adjacent to the

equipment hatch at 12 points,'four equally spaced on each of three concentric circles, and the change in diameter of the equipment hatch in the horizontal and vertical directions.

i Vertical displacements of the cylinder at the top relative to

the base at four azimuths.

• Vertical deflections of the dome of the containment near the l

apex and at two other locations between the apex and the

springline on one azimuth.

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Change in diameter of the equipment hatch barrel.

• Meters designated D1 through D8 measured the change in radius i

between the inner face of the cylinder and. interior reference structures.

Meters designated D9 through D14 recorded the change j

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in diameter of the cylinder above the operating floor.

Meters 021 through 032 measured the change in radius cf the cylinder around tha equipment hatch. Meters V1 through V4 recorded the change in elevation between the operating floor and the dome-wall springline.

Meters V9, V10, and V11 measured the change in distance between points on the dome and the operating floor.

Meters T1 and T2 recorded the change in diameter of the equipment hatch barrel.

Predicted displacement values are documented in Table 3.8-6 of the FSAR Amendment 44.

In general, the measured deflections are lower than the predicted values. At two locations, the measured values exceeded predicted values.

The predicted response of D2 was 0.08 inches, and the measured response was 0.082 inch which is 2.5 percent greater. Meters D2 through 04 were all located at elevation 384 feet 6 inches.

Allowing for some rounding out at this elevation, they average 0.074 inch which is 7.5 percent less than the predicted value.

The predicted response of D6 was 0.20 inches, and the measured response was 0.229 inches, which is 14.5 percent greater.

The average of all measurements at this elevation (gages D5 through 08) is 0.178 inches which is 11 percent less than the predicted value.

Following depressurization, deflection recovery was monitored for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

In a majority of cases, the recovery exceeded 90 percent of maximum deflection.

In all but seven cases, the recovery within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after depressurization was 80 percent or more.

Recovery at D5 was 79.5 percent.

At 013 and D14, recovery was 70.1 and 59.0 percent respectively.

At V1 through V4, the average recovery was 69.8 percent with only slight variation between gages.

The average recovery of all gages was 87.0 percent.

e.

Cracking Ten areas were selected for detailed crack inspections.

The inspection areas had one foot square reference grid markings on the surface. The pretest crack inspection revealed only minor shrinkage cracks.

All cracks observed were less than 0.01 inches in width and 6 inches in length with the exception of the equipment hatch area at elevation 437 feet and azimuth 72 degrees which had one crack with 0.01 inch width.

During pressurization, few new cracks were observed.

Most old cracks remained essentially unchanged during the test.

There were some extensions and expansions of existing cracks.

All cracks measured were between 0.002 inches and 0.01 inches in width.

f.

Conclusions In most cases the measured deflections were less than predicted.

The average measured recovery at all locations was 87.0 percent.

The majority of the measurements appear to have essentially a linear response and good recovery.

This indicates that yielding of materials in the containment structure is not a concern. With the exception of D2 and 06, all displacements were less than predicted.

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The pretest cracks observed in the designated-areas were not significant in size or length, and are probably the result of thermal strains and/or drying shrinkage. These are believed to be surface cracks. No appreciable change in crack width was observed during pressurization to 57.5 psig. There was no sign of any structural distress at any time during or after the test. No visible signs of permanent damage to either the concrete or steel liner were detected.

The overall structural response demonstrated that the containment structure performed satisfactorily and maintained the desired structural integrity under design loading conditions.

3.

Exit Interview The inspector met with licensee representatives (denoted under Persons Contacted) on August 20, 1986. The inspector summarized the purpose and findings as reported herein. The inspector also discussed the likely informational content of the inspector's report with regard to documents or processes reviewed by the inspector during the inspection. The licensee did not identify any such documents / processes as proprietary.

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