ML20206Q571

SER Granting Util 860627 Request for Relief from ASME Section XI Inservice Hydrostatic Pressure Test Requirements. Alternative Exams Will Provide Necessary Added Assurance of Svc Water Sys Structural Reliability

ML20206Q571
Person / Time
Site:	Mcguire
Issue date:	09/03/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20206Q548	List: ML20206Q544 ML20206Q571
References
TAC-61884, NUDOCS 8609050046
Download: ML20206Q571 (4)

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-h' ENCLOSURE SAFETY EVALUATION REPORT ON RE00ESTS FOR RELIEF FROM INSERVICE INSPECTION REOUIREMENTS DUKE POWER COMPANY MCGUIRE NUCLEAR STATION UNIT 2 DOCKET NO. 50-370 t

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I. BACKGROUND By letter dated June 27, 1986, Duke Power Company (the licensee) requested relief from inservice hydrostatic pressure test requirements of the 1980

, Edition through Winter 1980 Addenda of Section XI of the ASME Code at McGuire Nuclear Station Unit 2. This report provides an evaluation of the licensee's requests, supporting information, and alternative examinations or tests, as well as the staff's bases for granting or denying the requests pursuant to 10 CFR 50.55a(g). The reliefs granted remain in effect for the first ten-year inspection interval unless revised or modified prior to the end of the interval . The relief requests are evaluated below.

II. EVALUATION OF RELIEF REQUEST

1. Class 2 Hydrostatic Pressure Test of Feedwater System Code Examination Requirement 4

After repairs by welding on the pressure retaining boundary, a system hydrostatic test shall be performed in accordance with IWC-5000.

Code Relief Request Relief is requested from performing the hydrostatic pressure test on four full penetration groove 2-inch pipe welds and five 2-inch socket welds on four separate feedvater lines, after feedwater system modification. The subject welds are on the reverse purge lines on the feedwater lines to the steam l genera tors.

Licensee Basis for Relief The main feedwater system supplies water to the steam generators where it removes heat from the reactor coolant system. Piping on Unit 2 feedwater (CF) .

system is to be modified in order to prevent a possible 2" Ifne rupture due to I insufficient weld size where the concentric reducer attaches to the 2" piping.

Performing a hydrostatic test on the feedwater piping would be impractical, extre:nely difficult, and very costly, due to the following reasons:

8609050046 860903 PDR ADOCK 05000369

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ENCLOSURE SAFETY EVALUATION REPORT ON REOUESTS FOR RELIEF FROM INSERVICE INSPECTION RE0VIREMENTS DUKE POWER COMPANY MCGUIRE NUCLEAR STATION UNIT 2 DOCKET NO. 50-370 I. BACKGROUND By letter dated June 27, 1986, Duke Power Company (the licensee) requested relief from inservice hydrostatic pressure test requirements of the 1980 Edition through Winter 1980 Addenda of Section XI of the ASME Code at McGuire Nuclear Station Unit 2. This report provides an evaluation of the licensee's requests, supporting information, and alternative examinations or tests, as well as the staff's bases for granting or denying the requests pursuant to 10 CFR 50.55a(g). The reliefs granted remain in effect for the first ten-year inspection interval unless revised or modified prior to the end of the interval. The relief requests are evaluated below.

II. EVALUATION OF RELIEF REQUEST

1. Class 2 Hydrostatic Pressure Test of Feedwater System '

Code Examination Requirement After repairs by welding on the pressure retaining boundary, a system hydrostatic test shall be performed in accordance with IWC-5000.

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Code Relief Request Relief is requested from performing the hydrostatic pressure test on four full

penetration groove 2-inch pipe welds and five 2-inch socket welds on four i separate feedwater lines, after feedwater system modification. The subject welds are on the reverse purge lines on the feedwater lines to the steam generators.

Licensee Basis for Relief The main feedwater system supplies water to the steam generators where it removes heat from the rcactor coolant system. Piping on Unit 2 feedwater (CF) .

system is to be modified in order to prevent a possible 2" line rupture due to insufficient weld size w1ere the concentric reducer attaches to the 2" piping.

Performing a hydrostatic test on tha feedwater piping would be impractical, extremely difficult, and very cost 1'y, due to the following reasons:

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(a) Isolation and preparation of this system would result in considerable additional radiation exposure to personnel.

(b) Additional time required to gag safety relief valves.

(c) Additional time required to pin or block main steam constant support hangers.

(d) Potential damage due to static load on main steam system caused by water solid condition.

(e) Potential damage to steam generator tube bundle.

(f) Potential leakage through main steam isolation valves, feedwater isolation valves, and other valves in the system (inability to hold pressure).

(g) Potential damage to instrumentation, or considerable delay due to isolation / removal of instrumentation.

(h) Loss of steam generator hydro cycle.

In addition to these reasons, the alternative examinations propos~ed below are

equal to or better than the required testing per the code. This area of the system falls into the same area as that for which reliefs from hydrostatic testing have previously been granted for McGuire.

Licensee Proposed Alternative Examination A 100% penetrant test of all boundary welds plus an additional inservice leak test with system at operating pressure will be perfomed. Also, a hydro will be performed at the ten-year inspection interval per Section XI of the ASME Code. These examinations, with the exception of the hydrostatic-test, will be conducted after the feedwater piping modification is complete and prior to the system being declared operable.

i Staff Evaluatior. and Conclusions t

Substantial manpower expenditure and occupational radiation exposure are i required to perfom the hydrostatic pressure tests. The licensee has proposed not to perform the hydrostatic tests after system modification. However, the licensee is committed to performing the nomally required hydrostatic tests during the ten-year inspection interval. A penetrant surface examination as I

proposed by the licensee is acceptable for assessing the integrity of socket r welds and small diameter piping welds. Furthermore, the additional inservice leak test as proposed will provide assurance of the integrity of the subject welds, i

l Based on the staff's evaluation and the licensee's discussion above, Code requirements are impractical. It is further concluded that the alternative examinations discussed above will provide necessary added assurance of the feedwater lines' structural reliability. The commission has determined to grant relief from the hydrostatic test requirements as requested based upon the conclusion that it is authorized bylaw, will not endanger life or property or the common defense and security, and is otherwise in the public interest.

l 3-t I 2. Class 3 Hydrostatic Pressure Test of Nuclear Service Water System Code Examination Requirement After repairs by welding on the pressure retaining boundary, a system hydrostatic test shall be performed in accordance with IWD-5000.

Code Relief Request Relief is requested from perfonning the hydrostatic pressure test on the inside and outside welds on two 18" slip-on flanges on the Nuclear Service Water System (RN) after system modification. The welds are numbered as 2RN2F2713, 2RN2F2714, 2RN132-4, and 2RN132-5 in Figure 1 in the licensee's submittal.

Licensee Basis for Relief An 84" section of carbon steel piping was removed from the RN system per NSM MG-20636 Rev. 1. An 84" section of stainless steel piping with flanged connections replaced the carbon steel section. The two subject slip-on flanges connect the stainless piping to the old carbon piping. The new stainless section contains the RN pump 2B flow element, and is located on the pump discharge header.

Hydrostatic testing of the subject welds would be impractical based on the following reasons:

(A) Section of piping containing subject welds cannot be adequately isolated for hydrostatic testing. Isolation valves are large butterfly valves ranging from 10" to 30" in sizes with a history of leakage.

(B) Attempts at hydrostatic testing between a blind flange and a Thaxton high pressure mechanical pipe plug failed. Irregularities on the inside surface of the RN piping due to corrosion, would not allow the plug to seat properly.

(C) Additional testing as specified below is better than required by ASME Class 3 requirements.

Licensee Proposed Alternative Test All welding was subject to MT examination. An inservice leak inspection was conducted per McGuire procedure MP/0/A/7650/76 at system pressure and temperature. All examinations have been done.

Staff Evaluation and Conclusions 1 The subject section of pipe cannot be isolated adequately for hydrostatic testing. Attempts to use a mechanical pipe plug for isolation failed.

However, the pipe plug held for RN Train A and that train was hydrostatically tested. This relief request is associated with RN Train B. A magnetic y,,.,,--.m- - , - _ . , . , . , . - , - - - - , , , - - . .e. , - _ , , . . _ _ . - - . - - , ,- _,a_n.n_, _ , , , - . - _ . _ . - . . - - . . , - . , - . - - - - ,,

3 I particle surface examination as proposed by the licensee is acceptable for assessing the integrity of subject Class 3 welds. Furthermore, the inservice leak test as proposed will provide assurance of the integrity of the subject welds.

Based on the staff's evaluation and the licensee's discussion above, Code requirements are impractical. It is further concluded that the alternative examinations discussed above will provide necessary added assurance of the Nuclear Service Water System's structural reliability. The Commision has de~

termined to grant relief from the hydrostatic test requirements as requested based upon the conclusion that it is authorized by law, will not endanger life or property or the common defense and security, and is otherwise in the public interest.

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