ML20133N371
| ML20133N371 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 07/23/1985 |
| From: | Hufham J TENNESSEE VALLEY AUTHORITY |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8508130468 | |
| Download: ML20133N371 (4) | |
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,. s TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374ot 1630 Chestn Street Tower II J UL 29 p,*,
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July 23, 1985 BLRD-50-438/83-56 BLRD-50-439/83-49 U.S. Nuclear Regulatory Commission Region II Attn:
Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Dear Dr. Crace:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - MASS OF HVAC SUPPORTS NOT INCLUDED IN FREQUENCY CALCULATIONS - BLRD-50-438/83-56 BLRD-50-439/83 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector P. E. Fredrickson on October 20, 1983 in accordance with 10 CFR 50.55(e) as NCR BLN BLP 8336. This was followed by our interim reports dated November 18, 1983, May 15, 1984, and February 27, 1985. Enclosed is our final report.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY
. W. Hufham, Manager Licensing and Risk Protection Enclosure cc (Enclosure):
Mr. James Taylor, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Comission Washington, D.C.
20555 Records Center Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite 1500 Atlanta, Ceorgia 30339 gD130460050723 s
ADock 05000430 PDR
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An Equal Opportunity Employer yg g
o' ga, "NCLOSURE DELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 MASS OF HEATING, VENTILATING, AND AIR-CONDITIONING SUPPORTS NOT INCLUDED IN FREQUENCY CALCULATIONS BLRD-50-438/83-56, BLRD-50-439/83-49 NCR BLN DLP 8316 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency Bellefonte Nuclear Plant (BLN) Design Criteria N4-50-D716, section 8.1, requires that the mass of a support be included in the evaluation of the natural frequency of that support in the restrained direction when the support's mass is greater than 50 percent of the supported mass.
A review of heating, ventilating, and air-conditioning (HVAC) support calculations initiated to address generic concerns of the separately reported item, nonconformance report (NCR) WBN SWP 8254 (CDR 390/83-48 and 391/83-46), has revealed that some supports identified in the TVA design drawing series listed below were not designed to criteria requirements.
The affected drawing series are:
4AWO867-X2 4AWO871-X2 4AWO868-X2 4AWO865-X2 4AWO869-X2 4AWO759-X2 4AWO870-X2 4AWO532-X2 TVA has determined that the cause of this deficiency was the ambiguous and misleading wording of section 8.1.
In the second paragraph of this section, two methods of designing duct supports (the allowable stress limit and the status deflection limit methods) are listed while the third paragraph discusses considerations used in the status deflection limit method only.
This paragraph contains the statement, "the weight of the support need not be considered unless it is estimated to be 50 percent or more of supported ducts weights." Since there was no mention of the weight of the support being included in calculations using the allowable stress limit, it was reasoned in some instances that such an inclusion was not required.
Safety Implications A continued failure to include support mass into natural frequency evaluations as required could result in support anchor loads or structural members exceeding design allowances.
This in turn could have caused support failures which degraded safety-related duct to the extent that safe operation of the plant could be adversely affected.
Corrective Action All duct supports in category I structures were investigated to determine if the support mass had been included in the design. Some supports were designed without the use of the supnort's mass in its design, but in nach such case the conservatism of the support's design was sufficient to allow the inclusion of the aupport mass without requiring any modification.
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To prevent a recurrence of this problem, design criteria N!4-50-D716 has been revised to clearly indicate that the mass of the support must be included in both the stress limit and the deflection limit methods for designing duct supports in a category I structure and to clearly distin:;uish between the two methods.
a nm TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374ol 1630 ChestnutyStreet Tower II G U J[i
' SS P l *. ! 0 July 23, 1985 BLRD-50-438/83-56 BLRD-50-439/83-49 U.S. Nuclear Regulatory Commission Region II Attn:
Dr. J. Nelson Grace, Regional Administrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Dear Dr. Grace:
BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 - NASS OF HVAC SUPPORTS NOT INCLUDED IN FREQUENCY CALCULATIONS - BLRD-50-438/83-56, BLRD-50-439/83 FINAL REPORT The subject deficiency was initially reported to NRC-0IE Inspector P. E. Fredrickson on October 20, 1983 in accordance with 10 CFR 50.55(e) as NCR BLN BLP 8336. This was followed by our interim reports dated November 18, 1983, May 15, 1984, and February 27, 1985.
Inclosed is our final report.
If you have any questions, please get in touch with R. H. Shell at FTS 858-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY
,d.
. W. Hufham, Manager Licensing and Risk Protection Enclosure cc (Enclosure):
Mr. James Taylor, Director Office of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, D.C.
20555 Records Center Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 An Equal Opportunity Employer
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ss-ENCLOSURE BELLEFONTE NUCLEAR PLANT UNITS 1 AND 2 MASS OF HEATING, VENTILATING, AND AIR-CONDITIONING SUPPORTS NOT INCLUDED IN FREQUENCY CALCULATIONS BLRD-50-418/83-56, BLRD-50-439/83-49 NCR BLN BLP 8316 10 CFR 50.55(e)
FINAL REPORT Description of Deficiency Bellefonte Nuclear Plant (BLN) Design Criteria N4-50-D716, section 8.1, requires that the mass of a support be included in the evaluation of the natural frequency of that support in the restrained direction when the support's mass is greater than 50 percent of the supported mass.
A review of heating, ventilating, and air-conditioning (HVAC) support calculations initiated to address generic concerns of the separately reported item, nonconformance report (NCR) WBN SWP 8254 (CDR 390/81-48 and 191/83-46), has revealed that some supports identified in the TVA design drawing series listed below were not designed to criteria requirements.
The affected drawing series are:
4AWO867-X2 4AWO871-X2 4AWOA68-X2 4AWO865-X2 4AWO869-X2 4AWO759-X2 4AWO870-X2 4AWO512-X2 TVA has determined that the cause of this deficiency was the ambiguous and misleading wording of section 8.1.
In the second paragraph of this section, two methods of designing duct supports (the allowable stress limit and the status deflection limit methods) are listed while the third paragraph discusses considerations used in the status deflection limit method only.
This paragraph contains the statement, "the weight of the support need not be considered unless it is estimated to be 50 percent or more of supported ducts weights." Since there was no mention of the weight of the support being included in calculations using the allowable stress limit, it was reasoned in some instances that such an inclusion was not required.
Safety Implications A continued failure to include support mass into natural frequency evaluations as required could result in support anchor loads or structural members exceeding design allowances. This in turn could have caused support failures which degraded safety-related duct to the extent that safe operation of the plant could be adversely affected.
Corrective Action All duct supports in category I structures were investigated to determine ~if the support mass had been included in the design. Some supports were designed without the use of the support's mass in its design, but in each such case the conservatism of the support's design was sufficient to allow the inclusion of the support mass without requiring any modification.
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A To prevent a recurrence of this problem, design criteria N!4-50-0716 has been revised to clearly indicate that the mass of the support must be included in both the stress limit and the deflection limit methods for designing duct supports in a category I structure and to clearly distinguish between the two methods.
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