ML20045G673

SER Authorizing Proposed Alternative Tests Per 10CFR50.55a(a)(3)(i).Concludes That Acceptable Level of Quality & Safety Will Be Maintained Using Proposed Alternative Tests Instead of Required Hspt

ML20045G673
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	07/09/1993
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20045G672	List: ML20045G671 ML20045G673
References
NUDOCS 9307150034
Download: ML20045G673 (3)

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UNITED STATES 10 NUCLEAR REGULATORY COMMISSION

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W ASHINGTON, D.C. 20S$5-0001 i

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RE0 VEST TO USE AN ALTERNATIVE TO THE ASME CODE HYDROSTATIC PRESSURE TESTS CONNECTICUT YANKEE ATOMIC POWER COMPANY HADDAM NECK PLANT l

DOCKET NO. 50-213 l

1.0 INTRODUCTION

In its letter of April 8, 1993, supplemented by letters of May 21, June 1, and i

June 25, 1993, Connecticut Yankee Atomic Power Company (CYAPCO), the licensee, submitted a request to use an alternative to the provisions of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, Summer 1983 Addendum, that requires hydrostatic pressure tests (HSPT) after performing repairs to the Class 3 service water system (SWS).

once the repairs are completed, the ASME Code requires that HSPT and a visual examination be performed on the repaired segments.

As stated in the I

submittal, the full HSPT of the SWS during this current outage would cause significant hardship in the form of additional downtime to perform the test, the locating and installing of additional hydrostatic pumps to pressurize the i

system, and the pressurization of large underground areas of the original SWS.

CYAPC0 has requested approval of the use of Code Case N-416, " Alternative Rules for Hydrostatic Testing of Repairs of Replacement of Class 2 Piping," as an alternative pursuant to 10 CFR 50.55a(a)(3)(i).

The proposed alternative consists of radiographic (RT) examinations of the butt welds and magnetic particle (MT) examinations of the root and final pass of the fillet welds, 1

including an inservice leak test performed at the normal system operating pressure.

2.0 BACKGROUND

CYAPC0 identified pitting in the elbows of the SWS between the main header and intake manifold of the A and B emergency diesel generators (EDGs).

CYAPC0 will replace the affected elbows and pipe segments on either side of the elbows with the same nominal size (6-inches) and wall-thickness (0.280-inch) carbon steel elbows and pipe segments.

The pipe segments'are connected to the i

main header with a saddle-designed end that is fillet welded over a smaller opening cut in the main header.

The opposite end of the pipe segments are butt welded to the 90 degree elbows, which in turn, are butt welded to other pipe segments in the EDG systems. After the repairs, the ASME requirement imposed on the repaired welds are:

IWA-4400(a) states that after repairs by welding on the pressure retaining boundary, a system hydrostatic test shall be performed in accordance with IWA-5000.

IWA-5214(b) states that the test pressure and 9307150034 930709 PDR ADOCK 05000213.

P ppg

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. temperature shall comply with IWD-5223.

IWD-5223(a) states that the system hydrostatic test pressure shall be at least 1.10 times the system for systems with design temperatures of 200* F or less, and pressure P,"25 times the P,y at least 1.

for systems with design temperature above 200* F.

The o, shall be the lowest pressure setting among the number of safety or relief valves provided for overpressure protection within the boundary of the system to be tested.

For systems (or portions of systems) not provided with safety or relief valves, the system design pressure P shall be substituted for P,,.

g The licensee proposed the following alternative requirements:

(1)

Invoke Code Case N-416, " Alternative Rules for Hydrostatic Testing of Repair of Replacement of Class 2 Piping Section XI, Division 1."

(2)

The fillet welds will receive magnetic particle examinations on the root and on the final weld, a visual examination of the welds, and an inservice leak test at normal system operating pressure.

(3)

The butt welds will receive radiographic and magnetic particle examinations, and an inservice leak test at normal system operating pressure.

3.0 EVALUATION AND DESCRIPTION Code Case N-416 is included in Regulatory Guide 1.147 " Inservice Inspection Code Case Acceptability ASME Section XI Division 1," Revision 9, April 1992, and is applicable to Class 2 systems. To use Code Case N-416, the repaired piping cannot be isolated by existing valves or that isolating the piping would require securing safety or relief valves. The repaired piping cannot be locally isolated.

There is a valve between the repaired piping and EDG; however, the other end of the piping is connected to a main header. A HSPT would require the locating and installing of additional hydrostatic pumps to pressurize the system, and the pressurization of large underground areas of the original SWS.

The application of Code Case N-416 to Class 3 system includes the consideration of weld accessibility, additional examinations, and the schedule for conducting a HSPT on the repaired segments. The welds are surrounded by several feet of clearance that provide easy access for tests and inspection.

Code Case N-416 requires RT and MT examinations of the butt welds, MT examinations of the finished surface of the fillet welds, and the system inservice leak test of the repaired segments.

In addition, the licensee will perform MT examinations of the root pass of the fillet welds. The above testing establishes the structural integrity of the joints in the absence of a HSPT.

Code Case N-416 allows for the deferment of the HSPT until the next regularly scheduled system HSPT.

The next system HSPT is scheduled for (approximately) 1997.

CYAPCO is committed to performing the required HSPT of the SWS at the

.. end of the present 10-year inspection interval, unless the ASME Code provisions change before then.

By invoking Code Case N-416, CYAPC0 has also committed not to use Code Case N-498, " Alternative Rules for 10-Year Hydrostatic Pressure Testing for Class 1 and 2 Systems," in 1997.

4.0 CONCLUSION

The staff concludes that an acceptable level of quality and safety will be maintained using the proposed alternative tests instead of the required HSPT.

Invoking Code Case N-416 with additional MT examinations ensures the structural integrity of the system.

Therefore, pursuant to 10 CFR 50.55a(a)(3)(i), the proposed alternative tests are authorized.

Principal Contributor:

D. Naujock Date: July 9, 1993