ML20003B447
| ML20003B447 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/03/1981 |
| From: | Mills L TENNESSEE VALLEY AUTHORITY |
| To: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 10CFR-050.55E, NUDOCS 8102120059 | |
| Download: ML20003B447 (4) | |
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400 Chestnut Street Tower II February 3, 1981 Mr. James P.
ellly, Director Office of Insp on and Enforcement U.S. Nuclear Regu ory Commission Region II - Suite 31 101 Marietta Street Atlanta, Georgia 30303
Dear Mr. O'Reilly:
SEQUOYAH NUCLEAR PLANT UNIT 2 - IMPROPERLY PRESSURIZED HYDROSTATIC TESTS -
NCR'S 2436, 2437, 2438, 2440-2443, 2447, 2448, 2449, 2457, AND 2462 -
REVISED FINAL REPORT The subject deficiencies were initially reported to NRC-0IE Inspector M. Thoans on November 26, 1980, in accordance with 10 CFR 50.55(e). A final report was submitted m December 24, 1980. Enclosed is our revised final report which addresses F. S. Cantrell's concerns as discussed with my staff m January 13, 1981.
If you have any questions, please get in touch with D. L. Lambert at FTS 857-2581.
Very truly yours, TENNESSEE VALLEY AUTHORITY L. M. Mills, Manager Nuclear Regulation and Safety l
Enclosure Mr. Victor Stallo, Director (Enclosure)/
cc:
Cffice of Inspection and Enforcement U.S. Nuclear Regulatory Commission Washington, DC 20555 l
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ENCLOSURE SEQUOYAH NUCLEAR PLANT UNIT 2 IMPROPERLY PRESSURIZED HYDROSTATIC TESTS NCR'S 2436, 2437, 2438, 2440-2443, 2447, 2448, 2449, 2457, AND 2462 10 CFR 50.55(e)
REVISED FINAL REPORT Description of Deficiency
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Approximately 12 hydrostatic tests in safety-related systems were conducted in which a portion of the piping in each test was subjected to the incorrect test pressure. The cause of this problem is the difficulty in establishing the appropriate pressure boundaries as indicated on flow diagrams. Sections of piping at areas of transition between high pressure and low pressure piping were tested at the incorrect pressure. Also, there was no formal CA document which detailed the procedure for conducting a hydrostatic test. There are three cases involved:
(1) Piping subjected to pressures higher than required for hydrostatic testing, (2) piping subjected to pressures lower than required for hydrostatic testing but higher than the system design pressure, and (3) 4 piping subjected to pressures lower than design pressure.
This condition is documented for Sequoyah unit 1 on NCR's 2481 and 2485 and NCR SQN SWP 8030.
Safety Implications Case 1: A review of vendor documentation and code requirements reveals that all components were hydro tested by the vendors to pressures higher than the TVA system hydro test pressure. Therefore, this case would not have caused damage to any components and the nystem has been shown to be adequate for its intended service. As a result, this case could not have adversely affected plant safety.
Case 2: Because this case resulted in piping being subjected to pressures at least as-high as the system design pressure, there is assurance that the piping is adequate to perform its intended function.
Case 3: Because this case results in the system being pressurized at levels below the system design pressures, there may not be adequate assur-ance that the piping is leak free at the required pressure. There-fore, this piping could sustain leaks during high pressure operation.
Only NCR's 2442 and 2457 applied to this case. Subsequent evalua-tion of the affected piping design and applicable code require-ments reveals chat all piping was subjected to pressures which satisfactorily demonstrate that all piping will perform its intended function. See Corrective Action for details.
Therefore, this condition could not have adversely affected plant i
safety.
Corrective Action Each instance of improperly pressurized hydrostatic tests was. evaluated and
. dispositioned on a case-by-case basis. The results are summarized on the attached sheets.
Additionally,-Sequoyah Nuclear Plant Inspection Instruction (SNP II) 41 has been revised to provide instructions for properly carrying out the hydrostatic j
tests. SNP II-41 provides for a review of the pressure boundaries and itest requirements (including G-29M requirements) before performance of the test.
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Design Test Correct flydro NCR No.
System Affected Piping Pressure (PSIG) Pressure (PSIG) Pressure (PSIG) Disposition Justification 200 225 Retest Case 2 2436 liigh Pressure Fire Suppression 60 Fire Prot.
Piping 2437 Demineralized Demineralized Water 100 150 125 Use as is.
Case 1 Water and Cask Piping Sections Decontamination 2438 ERCW 18" Piping, Including 240 200 Use as is Case 1 - Note 1 Containment Spray l60 lleat Exchangers 2A and 2B and 1-1/2" and 2" Piping 2440 CVCS 2" Seal Water 2735 3106 3418.75 Use as is Case 2 - Note 2 R1 Injection Lines (RCS Cold liydro Pressure) 2441 CVCS 3" Normal Charging 2735 3117 3418.75 Use as is Case 2 - Note 2 R1 Lines (RCS Cold liydro Pressure) 2442 CVCS 2" Letdown Line 600 250 750 Use as is Case 3 - Note 2 R1 (Note 5)
(Note 5)
Note 5 2443 CVCS 3" Piping Associated 150 187.5 262 51 Use as is Case 2 - Note 2 R1 With Instrument 2-FIT-62-142 2447 Ice Condenser Misc. Piping Sections 150 225 187.5 Use as is Case 1 2448 RilR Piping Sections Which 600 875 750 Use as is case 1 Were Tested in conjunction With A Portion of the Safety Injection System 2449 Waste Disposal Hisc. Piping Sections 150 150 187.5 Retest Case 2 2462 RCS Relier Valve Discharge 150 187.5 250 Retest case 2 Piping
Design Test Correct flydro NCR No.
System Affected Piping Pressure (PSIG) Pressure (PSIG) Pressure (PSIG) Disposition Justification' 2457 Flood Mode Piping Associated with Note 4 Note 4 Note 4 Use as is Note 3 R1 Boration Makeup 3" Normal Charging Line on Suction and Discharge of Auxiliary Charging Pumps Note 1:
TVA (Division of Engineering Design) analysis concluded that ' allowable stresses for the containment spray heat exchangers were not exceeded.
Note 2:
This case involves a nonisolable pressure chango.
Note 3: This was originally applicable to case 3 of the safety implications for a portion of the piping involved.
Ilowever, a review of design documentation indicates that the piping is ANSI B31.7, Class 3, and will be acceptable upon documenting an ANSI B31.1 leak check. This inspection is permitted to be performed at maximum operating pressure. The design pressures originally specified were chosen from standard conditions for the pipe schedule being used which are in excess of r.e inspection operating pressure. The hydro test and ANSI B31.1 leak test conducted was proper and acceptable. The flow diagram will be revised to show the existing bill of material specification.
Note 4:
Piping was hydro tested to 3106 PSIG between valve 2-84-502 (rather than 2-84-506) to valve 2-62-709 bec ause of the limiting component of auxiliary charging pump 2A.
The flow diagram was later revised to change the hydro boundary from the pump to valve 2-84-500.
As a result, this section is overpressurized and piping between the pump discharge and valve 2-84-502 is underpressurized.
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Note 5: This was originally applicable to Case 3 of the safety implications. The specified design pressure of 600 lb/in g was chosen from standard conditions fgr the pipe schedule which was procured. This pressure is in excess of the maximum operation pressure (200 lb/in g).
The hydrotest was conducted at a pressure of 1.25 x the maximum operating pressure. Therefore, there is sufficient assurance that the piping is adequate to perform its intended function.
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