ML20071N563
| ML20071N563 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 05/25/1983 |
| From: | Oprea G HOUSTON LIGHTING & POWER CO. |
| To: | Jay Collins NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, ST-HL-AE-963, NUDOCS 8306070112 | |
| Download: ML20071N563 (4) | |
Text
.
The Light Company ii.,,,si,,,, ugi,ii,o i,m im. ii.,x ir,,,, ii.,,,si,,,,. im,s 77,,,,i (7 3i mmii May 25, 1983 ST-HL-AE-963
)
File No.: G12.146 I
% R@ R M R %
'Mr. John T. Collins
- a W
legional Administrator, Region IV Nuclear Regulatory Commission
(
'\\
3g 611 Ryan Plaza Dr., Suite 1000 Arlington, Texas 76012
Dear Mr. Collins:
South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Final Report Concerning the Reactor Containment Fan Cooler Design On April 29, 1983, pursuant to 10CFR50.55(e), Houston Lighting & Power Company (HL&P) notified your office of an item concerning the duct layout of the Reactor Containment Fan Cooler (RCFC) system. Attached is the final report concerning this item.
If you should have any questions concerning this matter, please contact Mr. Michael E. Powell at (713) 877-3281.
Very truly yours,
/ '-
l
/
N
/ Executive V,tc President MEP/kr Attachment 4
')h' 8306070112 830525 PDR ADDCK 05000498
}q (
S PDR
[
~
~
Ilouston Lighting & Power Company May 25, 1983 cc:
G. W. Oprea, Jr.
(
ST-HL-AE-963 J. H. Goldberg File Number: G12.146 J. G. Dewease_
Page 2 J. D. Parsons D. G. Barker M. R. Wisenburg R. A. Frazar J. W. Williams R..J. Maroni J. E. Geiger H. A. Walker
.S.'M.
Dew J. T. Collins (NRC)
H. E. Schierling
'(NRC)
W. M. Hill, Jr.
(NRC)-
t M. D. Schwarz (Baker &Botts)
R. Gordon 200ch (Baker &Botts)
J..R. Newman (Lowenstein, Newman, Reis, & Axelrad)
STP RMS Director, Office of Inspection.& Enforcemeat Nuclear Regulatory Commission Washington,'D. C. 20555 G. W. Muench/R. Li Range Charles Bechhoefer, Esquire Central Power & Light Company Chairman, Atomic Safety & Licensing Board P. O. Box 2121 U. S. Nuclear Regulatory Commission Corpus Christi, Texas 78403 Washington, D. C.
20555 H. L. Peterson/G. Pokorny Dr. James C. Lamb, III
',.s City of Austin 313 Woodhaven Road P. O. Box 1088 Chapel Hill, North Carolina 27514 Austin, Texas 78767 a
i.
J. B. Pos' ten /A. vonRosenberg Mr. Ernest E. Hill City.Public Service Board Lawrence Livermore Laboratory San Antonio,rTexas 78296.
University of California P. 0., Box -1771 P. O. Box 808, L-46 Livermore, California 94550 Brian E. Berwick, Esquire dilliam S. Jordan, III Assistant Attorney General
'iarmon & Weiss i or the State of Texas 1725 I Street, N. W.
f c
~P2 0. Box 12548 Suite 506
. Capitol Station Washington, D. C.
20006 Austin,7 Texas 78711 Lanny Sinkin Citizens for Equitable Utilities, Inc.
Citizens Concerned About Nuclear Power c/o Ms. Peggy Buchorn
>5106 Casa Oro Route 1, Box 16fl4 San Antonio, Texas 78233 Brazoria, Texas 77422 I
Robert G. Perlis, Esquire
D Hearing Attorney Office of the Executive Legal Director U. S. Nuclear Regulatory Conunission -
Washington, D. C. -20555 Revision Date 04-29-83
FINAL REPORT CONCERNING THE REACTOR CONTAINMENT FAN COOLER DEFICIENCY I.
Summary The present layout of the Reactor Containment Fan Cooler (RCFC) system ductwork allows collection of water after initiation of the Containment Spray System (CSS). The RCFC ductwork could become flooded and system performance could be degraded, resulting in reduced heat removal capacity following a Design Basis Event (DBE). The corrective action will preclude such a condition.
II. Description of the Deficiency On April 29, 1983, pursuant to 10CFR50.55(e), Houston Lighting & Power (HL&P) notified the NRC-Region IV of an item concerning the design of the RCFC system. The potential exists for CSS water to flood the RCFC system discharge air ducts which could degrade the RCFC system performance. This was identified by Bechtel when they were reviewing the CSS spray coverage calculations.
Two of six RCFC discharge ducts are in the direct path of the containment spray. These ducts could flood and block the fan discharge. The design basis for the RCFC system is that three (3) of six (6) RCFC units function during a LOCA with a loss of offsite power. The limiting single failure which is assumed for the RCFC system is loss of a diesel generator, thus disabling two (2) of the six (6) RCFC units. However, the CSS will also be functioning during this event and the layout of the RCFC discharge air ducts is such that two (2) units could be flooded by the CSS, thus disabling the
.two (2) subject RCFC units.
If the flooded RCFC units are different than the ones disabled by a diesel generator failure, then only two (2) RCFC units remain operational. Therefore, the potential exists for the RCFC system not to be able to perform its intended safety function.
III Corrective Actions The water spray into the discharge ducts will be prevented by modifying the design of the discharge ducts. The previous ductwork layout discharged air directly upwards. The addition of a bend (an extension of the duct so the discharge of air will be horizontal) will prevent entry of the spray water into the duct.
IV. Recurrence Control The deficiency resulted from a failure to consider the effects of simultaneous operation of the RCFC and the CSS post-accident. Bechtel procedures for interdisciplinary and intradisciplinary design review minimize recurrence of such deficiencies by requiring that systems be designed with due consideration for operating conditions and system interfaces.
V.
Safety Analysis The safety implication is that reduced RCFC capacity would result in decreased ability to maintain post accident pressures as described in the
r:
~~
STP FSAR. The minimum RCFC capacity assumed in the safety analysis is three units.
In the current design two of the six RCFC fan discharge ducts are assumed to be flooded with spray water. Assuming a single failure of one train, two other RCFC fans would be unavailable. Therefore, the remaining two fans would not reduce the containment pressure as predicted and would not provide proper mixing of the air volumes inside containment.
l-l.
2 j
i
. - ~.. _ _ _. _ - _ _, _. _ _ -..,.. _ _.., _ -
.. -.