ML20032C500
| ML20032C500 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/28/1981 |
| From: | Kemper J 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 8111100492 | |
| Download: ML20032C500 (2) | |
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PHILAD ELPHIA ELECTRIC COM PANY~
23O1 M ARKET STREET
- u. -..-w P.O. BOX 8699 c' "wu m OOI'190I
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PHILADELPHIA. PA.19101 (2151841 4502 JOHN S. MEMPER V IC E PR ESI D E P4 7 t es(.eest a mesmo apso setse a ncee l
OCT 23 981 Mr. Ronald C. Ilaynes, Director United States Nuclear Regulatory Commission Office of Inspection and Enforcement, Region I 631 Park Avenue
(
King of Prussia, PA 19406
Subject:
Significant Deficiency Report #45 Second Interim Report of Containment Box Beam Design Deficiencies Limerick Generating Station Uni's 1 f 2 NRC Construction Permit Nos. CPPR 106 f 107 4
Reference:
PECo Interim Report on Containment Box Beam Design Deficiencies dated August 7, 1981 File:
QUAL 2-10-2 (SDR #45)
Dear Mr. Haynes:
The purpose of this secoad laterim report on the subject design deficiency is to apprise you of our progre -s and our schedule for completion of the evaluation described in the refere % d interim report. At the time of issuing the referenced report it m expected that the reanalysis would be completed by mid October, 1981; however, the evaluation is not complete as explained below.
l l
As mentioned in the Reference, the pipe whip loads used in the I
original box beam design were based on then available criteria.
Since l
the original box beam design, two significant changes have occurred, exclusive of the previously reported design deficiency, which has prompted reanalysis of the box beams. These are 1). the pipe whip loads have been refined to comply with FSAR requirements and to be consistent with the Standard Review Plan and 7). the box beams have been more appropriately categorized as pipe restraints since this is their primary load carrying i
function, rather than as structural elements. The methodology for pipe restraint design uses a different design approach which allows the beams i
l to yield to a maximum ductility ratio of twenty (20), in order to absorb the energ" imparted by a postulated pipe break.
Based upon a preliminary, i
l and very conservative analysis, many of the box beams meet the required l
ductility criteria. However, since the beams are allowed to yicid, l
larger beam deficction must be considered. An assessment of the effects
(
of these deflections due to beam yielding on safety-related commodities, l
supported ncar or from the box beams, is being performed.
h'c are optimistic j
that the refined, detailed calculati >ns will show that these deflections can be tolerated and therefore will have 1.o significant effect on these 8111100492 811028 E
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.. nw' Mr. Ronald C, llaynes, Director Page 2 commoditics.
In addition, the FSAR will be revised to reflect the change in design philosophy and methodology for box beam analysis under pipe rupture loads. Until theedeta(10d analyses are complete, it cannot be determined if failurf to d,etect and resolve the problem would have affected the safety-of the plant s, Since the present method $f analysis requires more time, it is expected that the evaluation of the box beams will be complete by May 17, 1982, at which time a final report giving complete results will be issued.
Sincerely, L S Ah'.. f JJW/dmc/1/11 Copy to: Director of Inspection and Enforcement United States Nuclear Regulatory Commission Washingtor, DC 20555 J. P. rarr, Resident NRC Inspector
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