ML20150F024
| ML20150F024 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 07/01/1988 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8807180098 | |
| Download: ML20150F024 (5) | |
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- DUKE POWER COMPANY e
P.O. HOX 33189 CHAMLOTTE. N.O. 28949 HAL D. TUCKER ressresown vws cursierev (704) 3N631 y
July 1, 1988 U.S. Nuclear Regulatory Commission i
-Attention: Document' Control ~ Desk j
Washington, D'.C.
20555 l
Subject:
McGuire Nuclear Station, Unit 2 l
Docket No. 50-370 ASME Code Section XI Requirements Relief Request No. 88-06 Gentlemen:
1 Pursuant to 10CFR 50.55a(g)(5)(iii), find attached the subject request for relief from ASME Code Section XI Requirements pertaining to McGuire Nuclear Station's Unit 2 Safety Injection Accumulator Tank 2B.
As stated in the attachment,-the I
weld for which relief is being requested is part of the second period ISI in the first ten year ISI interval. The current Unit 2 outage is the first outage of i
that period; therefore, it is requested that a response be provided prior to the Unit 2, sixth refueling cycle outage, (approximately Febuary 1,1990).
i l
Pursuant to 10CFR 170.3(y), 170.12(c), and 170.21 find enclosed an application fee of $150.00.
j Should there be any questions concerning this matter, please contact S.E. LeRoy at (704)373-6233.
Very truly yours, k/B.s/
m P
Hal B. Tucker SEL/78/sbn Attachment xc:
Dr. J. Nelson Grace Mr. W.T. Orders Regional Administrator, Region II NRC Resident Inspector U.S. Nucicar Regulatory Commission McGuire Nuclear Station 101 Marietta St., NW, Suite 2900 Atlanta, GA 30323 fh Mr. Darl Hood i
U.S. Nuclear Regulatory Comission d
Office of Nuclear Reactor Regulation g (Y g(
Washington, D.C.'
20555 f,$71hk$
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DUKE POWER COMPANY McGUIRE NUCLEAR STATION, UNIT 2 Relief Requast No. 88-06 REQUEST FOR RELIEF FROM ASME CODE SECTION XI REQUIREMENT DETERMINED TO BE IMPRACTICAL 1.
Component For Which Relief Is Requested:
A.
Name and Number:
The weld for which relief is being requested is the Safety Injection Accumulator Tank 2B Shell to Lower Head weld, number 2ACCB-06-01.
As shown in the attached drawing the circumferential weld:is located under 3.
the support skirt. of the tank preventing access to the subject weld to perform examination preparation and ultrasonic examination.
B.
Function:
The accumulators at McGuire (4 per unit) are pressure vessels filled with borated water and pressurized with nitrogen gas.
During normal operation each accumulator la isolated from the Reactor Coolant system by two check valves in series.
One accumulator is attached to each of the cold legs of the Reactor Coolant system.
Connections are provided for remotely adjusting the level and boron concentration of the borated water in cach accumulator during normal operation as required. Accumulator water level may be adjusted either by draining to the reactor coolant drain tank, or by pumping borated water from the refueling water storage tank to the accumulator using the safety injection pumps. Accumulator pressure is provided by a supply of nitrogen gas, within their own volume, and can be adjusted as required during normal operation; however, the accumulators are normally isolated from the source of this nitrogen supply. Gas relief valves on the accumulators protect them from pressures in excess of design pressure.
The accumulators are located within the Containment but outside of the secondary shield wall which protects them from missiles. The parameters of the accumulator tanks are as follows:
I o
Design Pressure, psig 700 o
Design Temperature, *F 300 o
Operating Temperature. *F 60-150 o
Normal Operating Pressure, psig 455 o
Minimum Operating Pressure, psig 430 o
Total Volume, cubic feet 1350 each j
o Minimum Water Volume, cubic feet 1075 each o
Volume of Nitrogen Gas, cubic feet 275 o
Boric Acid Concentration, Nominal, ppm 2000 o
Relief Valve Setpoint, psig 700 i
C.
ASME III Code Class:
l l
Equivalent Class 2
D.
Materials and Welds 4
The accumulator tanks are carbon steel (SA-284) with clad welded Stainless Steel (SA-240) lining.
The weld for which relief is 4
requested is weld no.t.2ACCBa&G-01, and is a 0.96 inch double bevel weld.
4 i
2.
ASME Code Section XI Requirement That Has Been Determined To Be Impractical:-
ASME Boiler and Pressure Vessel Section XI, 1980 Edition through Winter 1980 addenda, Article IWC-2500-1, Item C01.010.051.
The code requires the inspection of one Shell to Upper Head weld and ora Shell to Lower Head weld as part of the requirement to complete the equivalent of one vessel during the 120 month interval.
3.
Basis For Requesting Relief:
The ASME code requires that all of the welds associated with the subject tank be inspected during the 120 month ISI interval. The code allows that welds be chosen at random form the total of 4 tanks as long as the welds collectively are equivalent to the total welds of one tank.
During the Unit 2 fourth refueling outage currently in progress, inspection preparation personnel entered the reactor building to access the subject tank and found that the weld to be inspected was inaccessible. The circumferential weld is located inside the tank support skirt and is approximately ene inch from where the skirt is welded to the tank.
It was determined that the required ultrasonic examination could not be performed r
due to the lack of space to prepare the wald and perform the inspection.
This situation exists for all four of the Unit 2 accumulator tanks however, l
Accumulator Tank 2B is the involved tank at this time. Unit 1 will be inspected for similar problems in a future outage.
4.
Alternative Testing:
Duke proposes to perform an ultrasonic examination of the Shell to Upper Head weld for Accumulator Tank 2B, 5.
Why The Alternate Proposed Testing Will Provido An Acceptable Level Of Quality And Safety:
The Shell to Upper Head weld and Shell to Lower Head weld are identical in
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size, material, and type cf weld, The results of the alternate testing should be indicative of the conditions that exist for the weld that is inaccessible.
6.
Implementation:
9 The inspection is scheduled for the current Unit 2, fourth refueling outage; I
however, the weld must be inspected or alternate testing must be performed prior to the end of the Unit 2, sixth refueling outage, because the weld is part of the second period of the first 10 year ISI interval. This current Unit 2 outage is the first outage in the second period of the first 10 year i
ISI interval.
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