ML20011D644
| ML20011D644 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 12/20/1989 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 8912280148 | |
| Download: ML20011D644 (8) | |
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..s TENNESSEE VALLEY AUTHORITY CH ATTANOOGA. TENNESSEE 37401 SN 157B Lookout Place DEC 201888 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C.
20555 Gentlemen:
q In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 SEQUOYAH NUCLEAR PLANT (SQN) - REQUEST FOR RELIEF fr0M THE REQUIREMENTS OF THE 1
AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE SECTION XI - HYDROSTATIC PRESSURE' TEST REQUIREMENTS
Reference:
TVA letter to NRC dated January 31, 1989, "Sequoyah Nur. lear Plant (SQN) Units 1 and 2 - Revision to In-Service Pressure Test (ISPT) Program" Enclosed is a request for relief from the ASME Code,Section XI, hydrostatic test requirements involving SQN's residual heat removal (RHR) system for Units 1 and 2.
This exemption is associated with plant modifications for installing flow instrumentation on the RHR spray piping.
These modifications are part of TVA's commitment for upgrading SQN to satisfy the requirements of Regulatory Guide 1.97.
The enclosed request for relief concerns a postmodification te. ding requirement contained in paragraph IHC-5222 (Item c) of the ASME Beller and i
Pressure Vessel Code,Section XI, 1977 Edition, Summer 1978 Addenda. TVA has determined that conformance with this code-requirement would result in hardship and unusual difficulties with no compensating increase in the level of quality and safety.
TVA proposes to perform alternative testing that is considered to be an adequate demoastration of leak tightness for the modified RHR piping. Consequently, the proposed code excmption is being submitted in accordance with 10 CFR S0.55a(a)(3) and 10 CFR 55a(g)(Shill).
Enclosure I contains a description of the piping modification and the associated TVA drawings showing the affected areas. contains the request for relief.
The RHR spray modifications are currently scheduled for the Cycle 4 refueling outages for both units. Unit 1 is the lead unit with the Cycle 4 refueling outage projected to begin in April.1990.
The Unit 2 Cycle 4 refueling outage is projected to begin in October 1990.
This request for relief is being submitted at this time to support the Unit 1 outage work activities.
TVA' requests that NRC's response be provided before February 15, 1990.
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An Equal Opportunity Employer
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U.S. Nuclear Regulatory Commission DEC 201989 Please direct questions concerning this issue to Don V. Goodin at (615) 843-7734.
Very truly yours, 4
TENNESSEE VALLEY AUTHORITY v
i Mana r, Nuc Licensing and Regulatory Affairs Enclosures cc (Enclosures):
Ms. S. C. Black, Assistant Director for Projects TVA Projects Division U.S. Nuclear Regulatory Commission One Hb'te Flint, North 11555..ockville Pike Rockville, Maryland 20352 Mr. B. A. Wilson, Assistant Director for Inspection Programs TVA Projette Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NH, Suite 2900 Atlanta, Georgia 30323 NRC Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379
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Description of the Modification 1
l The 8-inch-diameter piping between the residual heat removal (RHR) heat exchanger and the RHR containment spray header is to be modified to receive an annubar flow element (see Figure 1).
These flow elements will be identified as FE-72-40 for Train A and FE-72-41 for Train B.
I Fese flow elements will be located in the auxiliary building downstream l
.N the normally closed spray isolation valves (CV-72-40 and FCV-72-41 (see Figure 2).
This modification requires that a 1.06-inch-diameter hole be drilled in the piping and a 1.25-inch fitting be welded onto the outside wall of the pipe. FE-72-40'will be installed at Elevation 705.5 and FE-72-41 will be installed at Elevation 715.5.
l II. Basis for Relief The American Society of Mechanical Engineers (ASME) Code,Section XI, requires that a pressure test be performed following repair, l
replacement, or system alteration (paragraph IWA-5214).
The piping affected by this modification is an open-ended section of piping and therefore cannot be hydrostatically tested in the normal manner. Paragieph IHC-5222. Item c, of the ASME code states:
"... For open ended portions of discharge lines in nonclosed systems (such as containment spray header), any test that demonstrates unimpaired flow shall be acceptable in lieu of a system pressure test."
Based on this provision, TVA would be required to conduct a special l
performance of Surveillance Instruction (SI) 138, " Containment Spray - Spray Nozzic Test," which is periodically performed every 5 years to satisfy SQN Technical Specification 4.6.2.1.2.b.
This test consists of blowing heated air into the piping and up through the RHR spray nozzles. An infrared photo ensure that all nozzles are open. graph of the spray header is taken to The unimpaired flow test using hot air is a difficult test to perform since it requires that TVA rent a special air compressor to be brought onsite (requires a five to seven week leadtime) to provide a source of compressed air.
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III. Alternative Testinq l
In lieu of the unimpaired flow test using heated air, TVA proposes the performance of a special hydrostatic pressure test.
The proposed test
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consists of pressurizing the modified pipir.g by filling the piping with water up to the maximum elevailon permissible while-ensuring that no water is discharged into containment through the spray header (Elevation 820). 'TVA will then perform a VT-2 visual examination of the welded connections to ensure no leakage.
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t IV. Conclusion TVA requests relief from the hydrostatic pressure test requirements of the ASME Section XI code for the RHR spray modification for SQN Units 1 and 2.
Performance of an unimpaired flow test to conform with the code requirement has been determined by TVA to result in hardship and-unusual difficulties with no compensating increase in the level of quality and safety.
TVA finds the proposed alternative test method to be an adequate demonstration of leak tightness for the modified RHR piping.
This relief request is submitted in accordance with 10 CFR 50.55a(a)(3) and 10 CFR 50.55a(g)(5)(lli).
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Request for Relief Unit:
I and 2 System:
FSAR Drawing:
Figure 6.2.2-2 (47W812-1)
Components:
8-inch piping to the RHR containment spray header ASME Class:
2 Function:
Provides flow path from the RER heat exchangers to the RHR containment spray header in the reactor building.
k Impractical Test Requirements:
Paragraph IWC-5222, Item c, of the ASME Code.
. For open ended portions of discharge lines in nonclosed systems (such as containment spray header), any test that demonstrates unimpaired flow shall be acceptable 1
in lieu of a system pressure-test."
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Basis for Relief: The 8-inch piping between the RHR heat exchanger and the RHR containment spray header is to be modified to receive an annubar flow element. This modification requires that a 1.06-inch-diameter hole be drilled in the 8-inch pipe and a 1.25-inch fitting be welded onto the outside wall of the pipe. TVA's ASME Section XI program requires that a hydrostatic pressure test be performed following this modification. The section of piping in which this modification is bein;g made is downstream f rom the containment spray header isolation valves (FCV-74-40.
and -41) and therefore cannot be hydrostatically tested in the normal meaner.
TVA'c periodic Section XI hydrostatic test for this piping consists of blowing bot air into the piping and through the containment spray nozzles and taking an infrared photograph of the spray header to ensure that all the nozzles.are open.
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. i-l The hot air unimpaired flow test is a difficult test to perform since it requires that a special air compressor be j
brought onsite to provide heated compressed air and that a special infrared camera be used. Performance of this test
'is required at 10-year intervals by the ASME Code. Dais test is also performed'at 5-year intervals at SQN as required by the plant technical specifications. ~This periodic test schedule does not coincide with the RHR spray-modification schedule.
Alternative Testing:
In addition to'the required nondestructive examinations.
TVA proposes the performance of a special hydrostatic test of the modified piping. -The proposed hydrostatic test will consist of pressurizing the modified piping by filling the piping with water to the maximum. elevation permissible, while ensuring that no water is discharged into the reactor containment building (Elevation 820).
TVA will then perform a VT-2 visual examination for leakage at the welded connections. TVA considers the proposed alternative test method to be an adequate demonstration of leak tightness for the modified RHR piping.
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