ML20063K148
| ML20063K148 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 08/30/1982 |
| 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-875, NUDOCS 8209030228 | |
| Download: ML20063K148 (4) | |
Text
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The Light co m p e y ii"-'""iix'i"x&ie<<
n ito ii",i7"" ii""s'"".reses77""i <7's>228-92ii August 30, 1982 ST-HL-AE-875 File Number:
G12.I16 SFN: V-0530
[l Mr. John T. Collins Regional Administrator, Region IV
- 1 Nuclear Regulatory Commission j
30 @
611 Ryan Plaza Dr., Suite 1000 L
Arlington, Texas 76012
[b.
Dear Mr. Collins:
South Texas Project Units 1 & 2 Docket Nos. STN 50-498, STN 50-499 Second Interim Report Concerning the Design of the Residual Heat Removal S: stem on March 26, 1982, llouston Lighting & Power Company (HL&P), pursuant to 10CFR50.55(e), notified your of fice of an item concerning the design of the Residual Heat Removal (RHR) System. Attached is the Second Interim Report which provides several alternatives for corrective actions which are currently under review. The final report will be submitted to your office by January 21, 1983 and will describe the corrective action to be implemented.
If you should have any questions concerning this item, please contact Mr. Michael E. Powell at (713)877-3281.
Very tru y'yours,
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rea, J.
Exec'tive Yi e President MEP/mg Attachment
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DOh8820830 R
050C049g S
1 u s M
Houston Lighting & Power Company l
cc:
G. W. Oprea, Jr.
File Number: G12.116 J. H. Goldberg Page 2 J. G. Dewease J. D. Parsons D. G. Barker C. G. Robertson R. A. Frazar J. W. Williams R. J. Maroni J. E. Geiger H. A. Walker S. M. Dew J. T. Collins NRC D. E. Sells NRC W. M. Hill, Jr.
NRC M. D. Schwarz (Baker &Botts)
R. Gordon Gooch (Baker & Botts)
J. R. Newnan (Lowenstein, Newman, Reis, & Axelrad)
STP RMS Director, Office of Inspection & Enforcement Nuclear Regulatory Comission Washington, D. C. 20555 G. W. Muench/R. L. Range Charles Bechhoefer, Esquire Central Power & Light Company Chairman, Atomic Safety & Licensing Board P. O. Box 2121 U. S. Nuclear Regulatory Commission Corpas Christi, Texas 78403 Washington, D. C.
20555 H. L. Peterson/G. Pokorny Dr. James C. Lamb, III City of Austin 313 Woodhaven Road P. O. Box 1088 Chapel Hill, North Carolina 27514 Austin, Texas 78767 J. B. Poston/A. vonRosenberg Mr. Ernest E. Hill City Public Service Board Lawrence Livermore Laboratory P. O. Box 1771 University cf California San Antonio, Texas 78296 P. O. Box 808, L-46 Livernore, California 94550 Brian E. Berwick, Esquire William S. Jordan, III Assistant Attorney General Harnon & Weiss for the State of Texas 1725 I Street, N. W.
P. O. Box 12548 Suite 505 Capitol Station Washington, D. C.
20006 Austin, Texas 78711 Lanny Sinkin Citizens for Equitable Utilities, Inc.
I Citizens Concerned About Nuclear Power c/o Ms. Peggy Buchorn l
5106 Casa Oro Route 1, Box 1684 l
San Antonio, Texas 78233 Brazoria, Texas 77422 Jay Gutierrez, Esquire Hearing Attorney Office of the Executive Legal Director U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Revision Date 08-23-82
1
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Sec'ond Interim Report i
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Concerning the Design
,4 of the Residual Heat Removal System j
+i I.
Summary
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The elevation difference betwcen the top of the Residual Heat Removal (RHR) heat exchanger tube bundle and the high water level in the Refccling1' Water Storage Tank (RWST) could result in leakage across the system check'
'j valves back to the RWST. This leakage could result in a voided volumejin the,--
heat exchanger tube bundle in which noncondensible gases could collect. The noncondensible gases could result in pctential waterhammer and air entrapment concerns when the Low Head Safety Injection (LHSI) pumps are started.
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This condition exists because of the iou NPfH requirements of the LHSI pumps which allow the RWST to be located at a relatively low plant elevation.;
The RWST is normally at a higher elevation than the RHR heat exchanger.-
e s Several alternatives for resolution of this item are outlined in Section III of this report.
S II.
Description of the Incident On March 26, 1982, Houston Lighting & Power Company (HL&P), pursuant t o
~
10CFR50.55(e), notified your office of an item concerning the design of the' RHR System. The RHR heat exchangers are located at an elevation higher than the RWST, which is the source of borated water for safety.iujedi; ion.
This configuration places the heat exchangers at the "high point" in the system, and therefore, subject to possible accumulation of none'o~ndensible gases in the tube bundles when the system is not in operation. The accumulation of noncondensible gases in the tube bundles could lead to a potential for water hammer when the LhSI pumps are started.
Brown & Root, Inc. (B&R) notified the NRC - Region IV office on March 26, 1982 that this item was potentially reportable pursuant to 10CFR21.
A copy of the B&R report concerning this item was provided as an attachment to our first interim report which was submitted to your office by letter dated April 21, 1982 (reference ST-HL-AE-818).
III.
Corrective Action The following alternatives regarding the modifications which may be required to preclude air entrapment in'the RER heat exchanger tube bundles are under consideration as resolutions to..the problems identified herein.
a.
The addition of a continuous or intermittent recirculation system to circulate fluid through the system to keep the piping full and to avoid stagnation which could lead to the 1
separation of noncondensibles.
b.
.The addition of an elevated or pressurized tank to maintain a positive head on the system.
e
s c.
A flowpath currently exists which is used for flow verification testing of the LHSI pumps during normal plant 1-operation. This flowpath could also be used to circulate fluid through the system to keep the piping full and to avoid stagnation which could lead to the separation of f;
noncondensibles.
IV.
Recurrence Control
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Any recurrence control measures which may be deemed necessary will be identified in the final report concerning this item..
V.
Safety Analysis Q
Pump startup with inadvertently voided discharge lines due to entrapped air or. draining has been identified as a potential-cause of water hammer by NUREG-0582 " Water Hammer in Nuclear Power Plants".
Water hammer events, due to this mechanism, are more common in systems where the relative elevations of components allow drainage of. lines due to normal system leakage, than in systems where the relative elevation of the water supply is such that the
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piping, after initial venting, tends to remain filled. The condition as described in this report. falls under the first category since the low relative position of the RWST could allow drainage of the RHR heat exchanger
'" tube bundles.
In water systems designed for operation with full pump discharge. lines, inadvertent' voiding of the lines due to air entrapment or drainage may result-in excessive dynamic loads following pump startup. The air results in higher liquid ve19 cities during the initial portion of the transient with attendant--
increased loads on the piping and possible higher pressures during the latter portion _o'f the transient us'the air is compressed.
-For these reasons, we have assumed that a safety hazard could exist and the design will be corrected without further analysis of the existing condition.