ML20128C060
| ML20128C060 | |
| Person / Time | |
|---|---|
| Site: | Bellefonte  |
| Issue date: | 04/18/1985 |
| From: | Hufham J TENNESSEE VALLEY AUTHORITY |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 8505280165 | |
| Download: ML20128C060 (2) | |
Text
.
g TENNESSEE VALLEY AUTHORITY
- CHATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II 35 APa 22 AN4 37,1985 BLRD-50438/84 BLRD-50-439/84-43 U.S. Nuclear Regulatory Commission RegLon II Attn:
Dr. J. Nelson Grace, Regional Araninistrator 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
Dear Dr. Grace:
BELLEFWTE NUCLEAR PLANI WITS 1 AND 2 - PorENfIAL FOR COOLER FAN FAILURE IUE TO UNEEIZED TERML OVEEGAD RELAY HEATER ELEENTS - BLRD-50-438/84-47, BLRD-50-439/84 FINAL EPORT The subject deficiency was initially reported to NRC-0IE Inspector P. E. Fredrickson on August 21, 1984 in accordance with 10 TR 50.55(e) as NCR BLN EB 8417 Our interim reports were submitted on September 19,1984 and March 13,1985.
Enclosed is our final neport.
If f>u have any questions, please get in touch with R. H. Shell at FT.W58-2688.
Very truly yours, TENNESSEE VALLEY AUTHORITY t$1 J. W. Hufham, Manager Licensing and Regulations Enclosure co:
Mr. James Taylor, Director (Enclosure)
. Office of Inspection and Enforcement U.S. Nuclear Regulatory Canaission Washington, D.C.
20555 i
Records Center (Enclosure)
Institute of Nuclear Power Operations 1100 Circle 75 Parkway, kite 1500 Atlanta, Georgia 30339 i-s = G b' >
8505200165 850418 J. d - ), 7 PDR ADOCK 05000438 S
PDR An Equal Opportunity Emp? oyer j
D N
ENQ,3 URE 1 j
BELLEFGETE NUCLEAR PLANT UNITS 11 AND 2 P0fENfIAL FOR COOLER FAN FAILURE g
DUE TO IX(IEH5IZED TIEREL 0FEILOAD RELAY HEATER ELEENTS BLRD-50438/8447,. BLRD-50439/84-43 10 TR 50.55(e)
NCR BLN EEB 8417 FINAL - EPORT
" Description of Deficiency LIn the final' mport to the NRC dated Atagust 24, 1984, on nonoonfomanoe L report (Nm) WBN NEB '8408 (WBRD-50-390/84-35 and WBRD-50-391/84-31), 'IV A identified 'a deficiency at Watts Bar Nuclear Plant -(WBN) in which three engineered ' safety feature -(ESP) cooler fan motors failed to start during lpreoperational test W-31F (integrated safety injection (SI) and station blackout ). The failure to start was attributed to inline thermal overload
..rel'ays which had tripped. This condition had previously occurred at WBN on preoperational test TVA-9C. Since Bellofonte Nuclear Plant (BLN) uses the same motor control center vendor (ITT-Gould) and uses the sane vendor sizing
' criteria,- there exists a potential for the same problem to occur at BLN.
Preop tests have not yet been conducted on BLN ESP heating, ventilating, and
" air-conditioning (HFAC) systems.- Thus, the assignable cause of this
. deficiency is indeterminate. However, TVA considers the probable cause to be as follows: The HVAC motors are operating at full load conditions. - At the blackout signal; (SI initiated), the HVAC motors are sequenced off, then -
? sequenced back on.-- During nonaal operation, the thersaal overload heaters are
. producing some heat, but not of sufficient amotet to actuate the internal bimetallic elements. When a motor is restarted, the higter inrush current F
produces ' sufficient heat which, in conjtection with the heater not having sufficient time to return to ambient temperature, results in the bimetallic
. element receiving enough heat to trip the motor.
I-Safety Iaplications Failure of safety-mlated HVAC motors to operate because of improperly sized P
thermal overload heater elements could allow safety-related equipment to overheat.. This overheating, in turn, could cause subsequent equipment performance degradation or failure which could adversely affect safe
- operation of the plant.
. Corrective Action TVA has completed a design study (EN DES calculation N4-CG-RP-03) which identified and evaltated overload heater sizing in BLN HVAC circuits. Based p
on the data obtained from the design study and TVA Design Guide D2-2 3 5, it was detemined that if the heater size was increased one size above the L
vendor recommendation, adequate overload protection would still exist and
- adequate assurance would be given that the affected safety-related ' load would j.
operate during accident conditions. Engineering change notice (Em) 3169 was
~
issued to implement these increased heater size changes. The EN DES calculation identified' those safety-mlated HVAC fan motor overload heater elements for which the overloads are to be replaced.
~
s e,
=e -
2 g
n, e
V L
m r s':
s
TVA beli0ve3 that this correttive cation will pr3 vent recurrance cf this deficien:y, and no further actions to provent.recurrsnoe cro required.
All design work and drawing revisions required per Eoi 3169 have been com pleted. All necessary constructio:t work will be completed by July 1, 1987 for unit 1 and by October 1, 1990 for unit 2.
P O
)
l l
l l
l 4
l
?
l
[
i l
2 I
1' l
L-1