ML20081E789
| ML20081E789 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 03/16/1995 |
| From: | Shell R TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9503210433 | |
| Download: ML20081E789 (6) | |
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NA insm VMey Autnwtpost OMa 6o0000, se, Ony Tennessee 37379 March 16,1995 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SON) - AUTHORIZATION TO USE AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) BOILER AND PRESSURE VESSEL (B&PV) CODE CASE N-498-1 Pursuant to 10 CFR 50.55aig)(5), TVA has determined that conformance with a pressure test requirement from Section XI of the ASME Code (1977 Edition, Summer 1978 Addenda) is impractical for SON Units 1 and 2. More specifically, TVA requests relief from the ASME code requirement for performing a periodic hydrostatic test on a Class 3 system. TVA proposes to utilize the alternative requirements of Code Case N-498-1,
" Alternative Rules for 10-Year Hydrostatic Testing for Class 1,2, and 3 Systems."
TVA is aware that the staff has not completed their review of this code case.
Consequently, TVA is requesting relief for specific application of Code Case N-498-1 on a plant system where a code hydrostatic pressure test has been determined to be impractical.
The alternative testing in Code Case N-498-1 is supported by the recent approval by the ASME as published on May 11,1994. The alternative requirements in ASME Code Case N-498-1 provide an acceptable level of quality and safety in lieu of the periodic hydrostatic testing. contains TVA's Request for Relief (ISPT-5). Enclosure 2 contains a diagram of the Class 3 hydrostatic pressure test boundary associated with ISPT-5.
NRC review and approval is requested before October 1,1995,in order to tajpport completion of SON's first 10-year inservice pressure test interval for both units. The first 10-year interval is scheduled to end in December 1995 for both units.
t 9503215433 950316 PDR-ADOCK 05000327
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U.S. Nuclear Regulatory Commission Page 2 March 16,1995 For further information concerning this issue, please contact D. V. Goodin at (615)843-7734.
Sincerely, V
R. H. Shell Manager SON Site Licensing Enclosures cc (Enclosures):
Mr. D. E. LaBarge, Project Manager Nuclear Regulatory Commission One White Flint, North 11555 Pockville Pike Rockville, Maryland 20852-2739 NRC Resident inspector Seqt ayah Nuclear Plant 260(. Igou Ferry Road Soddy-Daisy, Tennessee 37379-3624 Regional Administrator U.S. Nuclear Regulatory Comm!ssion Region 11 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323-2711
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'1 ENCLOSURE 1 1
INSERVICE PRESSURE TEST PROGi1AM (ISPT-5)
Units:
1&2 Components: : Class 3 pressure retaining components subject to hydrostatic testing in accordance with Table IWD-2500-1, Categories D-A, D-8, and D-C.
System:
Class:
3 Code
References:
Table IWD-2500-1, Categories D-A, D-B, D C, and IWD-5000.
Code Requirements: Table IWD-2500-1 provides the requirements for periodic pressure testing of pressure retaining components LWD-5000 provides the system test requirements.
Proposed Alternative:
TVA will implement the alternative requirements as stated in Code Case N-498-1.
"(1) A system pressure test shall be conducted at or near the end of each inspection interval or during the same inspection period of each inspection interval of Inspection Program B.
(2) The boundary subject to test pressurization during the system pressure test shall extend to all Class 2 components included in those portions of systems required to operate or support the safety system function up to and including the first normally closed valve, including a safety or relief valve, or valve capable of automatic closure when the safety function is required.
1 (3) Prior to performing the VT-2 examination, the system shall be pressurized to nominal operating pressure for a minimum of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> j
for insulated systems and 10 minutes for noninsulated systems.
The system shall be maintained at nominal operating pressure during performance of the VT-2 visual examination.
(4) The VT-2 visual examination shall include all components within the boundary identified in (c) (2) above.
(5) Test instrumentation requirements of IWA-5260 are not applicable."
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- Basis for the Proposed j
. Altornative:
ASME Code Case N-498-1 was approved by the ASME committee and published on May 11,1994, as an acceptable alternative to the rules for hydrostatic testing of Class 3 systems and components.
ASME Code Case N-498-1 allows for the performance of a VT-2 visual examination in conjunction with a system pressure test at nominal operating pressure in lieu of a code hydrostatic pressure test. No leaks through pressure retaining boundaries have been identified at SON during the performance of hydrostatic pressure tests on Class 3 systems. Any leakage noted is at flanged joints or at packing glands on pumps and valves. A number of utilities surveyed by ASME revealed that hydrostatic pressure tests cause an increase in the leakage rate when compared to leakage tests performed at nominal operating pressures.
However, no new leakage was identified by raising the test pressure from operating pressure to hydrostatic pressure. This signifies that hydrostatic pressure tests do not provide significant advantages for identifying pressure boundary leakage.
At SON, a section of Class 3 piping involving the AFW system remains to be hydrostatically tested during SON's first 10-year ISPT interval.
Specific hardships exist for completing the code-required hydrostatic pressure tests on this system. A description of the specific hardships is provided below.
In 1993, SON attempted to perform the code required hydrostatic test of Class 3 piping in the AFW system between Valves 1-FCV-1-15, 1-FCV-1-16,1-FCV-1-51 and associated piping up to Valves 3-916 and 3-915 (refer to the diagram in Enclosure 2). Valve 1-FCV-1-51 is the AFW turbine trip and throttle valve from the main steam system.
Valve 1-FCV-1-51 is designed to leak such that steam will not condense on the upstream side of the valve and inject condensate into the turbine when the valve opens. Because of the leak-through design of this valve, the test boundary would not maintain hydrostatic test pressure. TVA was unable to install a temporary blank to isolate Valve 1-FCV-1-51 from the pressure test boundary. This was due to the rigidity and geometric configuration of the piping system. Consequently, this section of AFW piping cannot be hydrostatically tested without a modification to the piping system.
j This test remains to be completed orior to the end of the first ISPT interval. TVA finds the provisions of ASME Code Case N-498-1 to be an acceptable alternative for demonstrating system integrity.
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3-4 ASME Code Case N-498-1.would allow testing to be performed at
- normal operating pressures, which.would ensure proper evaluation of the -
pressure boundaries. Therefore, the use of ASME Code Case N-498-1 is considered to be an acceptable alternative to the hydrostatic test requirements of ASME Section XI and provides an equivalent level of.
quality and safety.
Applicable -
Time Period:. Relief is requested for the first 10-year interval of the ISPT program for -
SON Units 1 and 2, which is scheduled to end in December 1995.
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4 ENCLOSURE 2 l
TEST BOUNDARY SKETCH
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M....
,I r w 3-892 FCV-1,- 16,, *
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3-891 FCV-1..15......
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FCV-1-18 FCW1-17 [
FCV-1-51 TURBINE ORIVEN AUXILIARY FEEDWATER PUMP,....
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8 PCV-3-183 g......'
- - N N-e 3-916 3-917 2,
3-919 e
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N-3-915 3-914 3-918 Notes:
- 1. TNs sketch identifies only rnakr test bouMaries. The visual exarnination shall
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be conduc*,ed with anarked inspection drawings develcped in test prerequisites.
" The test boundary is shown with dark, scEd lines.
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