ML19327A381
| ML19327A381 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 07/17/1980 |
| From: | Seidle W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Oprea G HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 8008060112 | |
| Download: ML19327A381 (1) | |
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UNITED STATEE NUCLEAR REGULATORY COMMISSION
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July 17, 1980 In Reply Refer To:
RIV Docket No. 50-498 50-499 Houston Lighting and Power Company ATTN: Mr. G. W. Oprea, Jr.
Executive Vice President Post Office Box 1700 Houston, Texas 77001 Gentlemen:
Thank you for your letter ST-HL-AE-472 of May 30,1980, that transmitted your final report of a 50.55(e) item, " Safety Injection System Piping Deficiency."
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In review of your report, we find that additional information is required.
Specifically, as discussed by Mr. Hubacek of this office with Messrs. Rodgers and Hernandez of your staff on July 9,1980, clarification of penetration details as shown on Figure 1 of the subject report is required.
The clarifi-cation should address disposition of the seal weld between the process pipe and the emergency sump liner.
Please provide us with the additional information within 30 days of receipt of this letter.
Should you have any questions concerning this matter, please contact this office.
Sincerely, f/
W. C. Seidle, Chief Reactor Construction and Engineering Support Branch 8C 8060//1* '
S 1.
The Light Company sou m u aiing & Power e o. B >x 1700 Houston. Texas 77001 (713) 228-9211 s
May 30, 1980 ST-HL-AE-472 SFN: V-0530 Director, Region IV Nuclear Regulatory Commission 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76102
Dear Sir:
South Texas Project Units 1 & 2 Final Report on the Safety Injection System Piping Deficiency On October 25, 1979, pursuant to 10 CFR 50.55(e), Houston Lighting and Power Company notified your office of a deficiency in the Safety Injection System containment emergency sump piping design.
The Interim Report of March 19, 1980, indicated that if the second design alternative
( i.e. anchoring the process pipe to the guard pipe) was found to be acceptable, a final report would be submitted by May 30, 1980.
In re-sponse to that commitment, attached is the final report.
Questions concerning this matter should be directed to Mr. Shawn Rodgers at (713) 676-7953.
Very truly yours,
. Q.. lm E. A. Turner Vice President Power Plant Construction
& Technical Services MP/mmf Attachment Qw y J, 2 00 & I E G TI b(Lj) o
Houston Ughting & Power Company ST-HL-AE-472 Page 2 cc:
G. W. Oprea, Jr.
D.'G. Barker C. L. McNeese H. R. Dean R. L. Waldrop G. B. Painter A. J. Granger R. A. Frazar M. D. Schwarz (Baker & Botts)
R. Gordon Gooch (Baker & Botts)
J. R. Newman (Lowenstein, Newman, Reis, Axelrad & Toll)
Director, Office of Inspection & Enforcement Nuclear Regulatory Commission Washington, D.C. 20555 M. L. Borchelt Executive Vice President Central Power & Light Company P. O. Box 2121 Corpus Christi, Texas 78403 R. L. Range Central Power & Light Company P. O. Box 2121 Corpus Christi, Texas 78403 R. L. Hancock Director of Electrical Utilities City of Austin P. O.
Box 1088 Austin, Texas 78767 M. C. Nitcholas City of Austin P. O. Box 1088 Austin, Texas 78767 J. B. Poston Assistant General Manager of Operations City Public Service Board P. O.
Box 1771 San Antonio, Texas 78296 A. vonRosenberg City Public Service Board P. O. Box 1771 San Antonio, Texas 78296 4
- - - -. ~, - -,
Houston Lufting & Pour, Company ST-HL-AE 472 Paga 3-Charles Bechoefer, Esquire Chairman, Atomic Safety & Licensing Board U.S. Nuclear Regulatory Comission Washington, D.C. 20555 Dr. James C. Lamb, III 313 Woodhaven Road Chapel Hill, North Carolina 27514 Dr. Emmeth A. Luebke Atomic Safety & Licensing Comission U.S. Nuclear Regulatory Comission Washington, D.C.20555 Steven A. Sinkin, Esquire 116 Villita Street San Antonio, Texas 78205 Citizens for Equitable Utilities c/c Ms. Peggy Buchorn Route 1, Box 432 Brazoria, Texas 77422 Richard W. Lowerre, Esquire Assistant Attorney General for the State of Texas P. O. Box 12548 Capitol Station Austin, Texas 78711 Henry J. McGurren, Esquire Hearing Attorney Office of the Executive Legal Director U.S. Nuclear Regulatory Comission Washington, D.C. 20555
FINAL REPORT SAFETY' INJECTION SYSTEM PIPING DEFICIENCY May 30, 1980 I.
SUMMARY
During a routine design review, a design deficiency was discovered in a Safety Injection System (SIS)/ Containment Spray System (CSS) containment emergency sump piping design.
The weld between the sump liner and the process pipe was not sufficient to carry the design loads.
If left un-corrected, a failure of the weld joint would create stresses in the associated recirculation valve that would exceed the design criteria.
Failure of this valve to open would prevent the SIS / CSS from perfonning its intended function of mitigating the consequences of an accident.
The deficiency will be corrected by anchoring the SIS / CSS process pipe to the guard pipe outside of the containment building and the addition of an expansion joint to the process pipe inside the emergency sumps.
Engineer-ing procedures will be revised to require all design not previously subject to the present design verification program to be re-design verified con-sistent with current Engineering procedures.
II.
DESCRIPTION OF THE INCIDENT During a routine review, a design deficiency was discovered which, if left uncorrected, could have adversely affected the safety of operations.
The joint between the 16 inch Safety Injection System piping and the emergency sump liner was shown on the construction drawing to be a one-quarter inch seal weld, which does not meet the design load criteria.
The piping is part of the SIS and CSS and leads from the containment emer-gency sump through the containment sump isolation valve to the safety in-l jection and containment spray pumps.
Following a LOCA, water will auto-matically be recirculated from the emergency sumps to the reactor by the Safety Injection System.
Operation of the containment emergency sump iso-lation valve is required for recirculation mode operations.
The seal weld in question attaches the process pipe to the sump liner.
III.
CORRECTIVE ACTION When this deficiency was discovered, the Engineer who identified the problem reported it on an Engineering Design Deficiency Report (EDD 79-39) as re-quired by Engineering procedures.
This deficiency will be corrected by anchoring the process pipe to the guard pipe outside the containment building and adding an expansion joint to the process pipe.inside the emergency sumps (see Figure 1).
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Attachment In determining that this installation is acceptable, the following
-factors and limitations were checked and verified as satisfactory:
Pipe Stresses Recirculation Valve End Loads Safety Injection Pump Load Limits Sump Liner Load Limits Containment Penetration Sleeve Load Limits Differential Settlement Criteria Containment Pressure Boundary Continuity Process Pipe and Guard Pipe Should Not Impact During a Seismic Event Constructability IV. RECURRENCE CONTROL.
Early in the STPEGS program, any engineer could perform verification on a designsso long as he was qualified and met the independence requirements.
As the result of an error found in the design of structural steel members (as documented in ST-HL-AE-346 dated June 5,1979), it was found that the quality:of the design verification program was being compromised by the pressures of meeting schedules.
This program was then substantially re-vised.
Each discipline was required to appoint individuals whose primary duties were that of the performance of design verification.
By procedure, i
each design verifier was to be given as much time as he needed to perform the verification task and each individual assigned to the verification function was made responsible to the Project Quality Engineer for the quality of this work.
This program was placed into effect in January,1979.
This error occurred prior to the implementation of this procedural change.
This deficiency indicates, however, that the adequacy of verification of designs issued prior to ~ January,1979 may require further evaluation.
Therefore, designs issued prior to January,1979 will be re-design verified consistent with current Engineering procedures.
This requirement will be added to the procedures before June 30, 1980.
Reverification will be com-pleted on a routine basis as documents are revised but, as a minimum prior to records turn-over and prior to fuel load.
V.' SAFETY ANALYSIS J
i If this deficiency were to have been left uncorrected, the weld at sump
-liner / process pipe interface could fail..The process pipe would then be free of restraint and would impose a load on the recirculation valve which exceeds the allowable end loads.
It could not then be guaranteed that the t-valve would operate as required.
Because this problem affects 'all three trains,- this is a common rede failure which could cause loss of safety system functions...
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