ML20054H287

Final Significant Deficiency Rept 62 Re Overstressed Box Beam Connections at Containment Wall & Bioshield.Design Changes for Box Beam & Column Connections at Elevation 296 Ft Will Be Issued by 820813

ML20054H287
Person / Time
Site:	Limerick
Issue date:	06/10/1982
From:	Boyer V PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Haynes R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8206230201
Download: ML20054H287 (2)

Text

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A PHILADELPHIA ELECTRIC COMPANY d >

23O1 M ARKET STREET i

1 y P.O. BOX 8699 1881 -1981 PHILADELPHI A. PA.19101 (215)841-4500

v. s. oo vcn wE 10 E2 SH. VIC E PRESIDENT NUCLE AR POWE R Mr. Ronald C. Haynes, Director United States Nuclear Regulatory Commission Office of Inspection and Enforcement, Region I 631 Park Avenue King of Prussia, PA 19406 Subj ec t : Significant Deficiency Report #62 Final Report on Overstressed Box Beam Connections at Containment Wall and Bioshield Limerick Generating Station, Units 1 and 2 htC Construction Permits nos. CPPR 106 and 107

Reference:

PECo. Report on Containment Box Beam Design Deficiencies dated May 14, 1982 File: QUAL 2-10-2 (SDR#62)

Dear Mr. Haynes:

It was previously reported in the Reference that the reanalysis of the box beams was " extended to assess the adequacy of beam connections to the containment wall and the bioshield and ptaliminary indications are that ten of the seventy-seven connections to the containment wall are overstressed and some modification may be required." The final analysis has been completed and a summary of our conclusions follows:

Box Beam and Column Connections @ EL 296'-0".

gum There are two high energy lines at EL.296-0". The connections were gg designed for the smaller of the two pipe whip loads from a postulated o- high energy line break at this elevation. Using the larger load in the

$0 reanalysis resulted in the overstressing of the connection of the box g

yo beams to the containment wall, for all nine radial beams. As a result of this reanalysis, some welds at the connections will also have to be o reinforced. We are in the process of designing modifications for the

$ beam connections at this elevation. These design changes will be issued g by August 13, 1982.

vu-jy0 Remaining Box Beam Connections:

All beam connections in the containment have been reanalyzed using pipe whip loads that have been refined to comply with the FSAR requirement and to be consistent with the SRP. Based on this reanalysis it was found that the connections of all remaining box beams meet the design ,

requirements except one at the containment wall at EL. 272-0". r, -

Box Beam Connections @ EL 272'-0:

The previous design was based on the loads calculated by the methodology available at the time. Since the original design, the pipe whip loads have been refined. This new approach resulted in higher loads and due to this increased load the pin and the supporting plate for one beam was found to be overstressed. The fix at this elevation will consist of the addition of one structural member connected between the box beam in question and an adjacent box beam at this elevation. This will redistribute the load to the next box beam and relieve the overstress on the pin and the supporting plates. This change will be issued by June 11, 1982.

Safety Implication We are reporting this item in compliance with the requirements of 10CFR 50.55 (e),

since significant rework will be required to ensure safe operation under postulated conditions.

HWV/dmj 2/5 Sincerely, 7

v. S. Boyer Senior Vice President Nuclear Power Copy to: Director of Inspection and Enforcement US Nuclear Regulatory Commission Washington, DC 20555