ML20212E211
| ML20212E211 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 02/20/1987 |
| From: | Kowalski S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Muller D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8703040293 | |
| Download: ML20212E211 (2) | |
Text
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PHILADELPHIA ELECTRIC COMPANY 23O1 M ARKET STREET P.O. BOX 8699 PHILADELPHI A. PA.19101 (2151841-4502 Vic E-PR ESIDE NT tesesseesnesse ano massances Mr. Daniel R. Muller, Director Docket Nos.: 50-277 BWR Project Directorate #2 50-278 Division of BWR Licensing U.S. Nuclear Regulatory Commission i
Washington, DC 20555
Subject:
Peach Bottom Atomic Power Station Units 2 & 3 Torus Attached Piping Modifications - Mark I Program Use of Actual Material Properties for Piping Stress Evaluation
Reference:
General Electric Document NED0-24583-1 Mark I Containment Program Structural Acceptance Criteria Plant Unique Anslysis Application Guide
Dear Mr. Muller:
The reference document requires that we obtain NRC approval of the use of structural acceptance criteria other than that provided in the 1977 ASME Boiler and Pressure Vessel Code Section III, Division 1, Summer 1977 Addenda prior to implementation. This letter is to inform you and seek your approval of the intended use of actual material properties from Certified Material Test Reports (CMTRs) for determining allowable piping stress in the resolution of Mark I containment hydrodynamic loads at the Peach Bottom Atomic Power Station Unit 3.
Actual material properties will be utilized in a single instance to qualify a piping system which has a stress combination level that slightly exceeds the code allowable.
This situation involves the Unit 3 RHR system outside containment in the vicinity of a torus nozzle. This one location is a tapered transition to a valve. The stress combination level that exceeds the code allowable is the upset (Level B) combination. All other loading combinations and associated stress levels meet code allowables. The load case involved is Pressure + Weight + SRV less than or equal valvesfbr,whereSRVIBA/SBA Lbbk.is multiple SRV actuakkhn of six adjacent to 1.2 S The calculated stress combination level is 18,104 psi whereas code allowable is 18,000 psi (0.6% over code allowable).
For this stress combination to occur, it is necessary to have an SRV event occur simultaneously with reactor coolant leaking past normaklyclosedvalves,resultinginthepressureinthelinereaching i
g l
the set point of the thermal relief valve.
In reality, the pressure should never reach the thermal relief valve set point since instrumentation is provided to alert the operators of a high pressure condition in this piping so that corrective action can be taken.
8 8703040293 B70220 A
PDR ADOCK 05000278 860,3 MIO
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I An allowable stress of 21,896 psi was calculated using-the CMTR values of yield strength, Sy, and ultimate strength, Su.
The allowable strength was taken as the minimum of 1/4 Su or 5/8 Sy which is consistent with the 1977 ASME B&PV Code,Section III, Division 1 through the Summer 1977 Addenda, used to qualify this piping for Mark I hydrodynamic loading. This allowable stress is based upon a stress intensification factor (SIF) of 1.77.
Note that if NC-3650 from the 1980 ASME B&PV Code,Section III through the Winter 1981 Addenda were used, the stress combination would be well below the code allowable.
We request approval of the use of actual material properties as outlined above, by March 31, 1987.
Should you require any further information do not hesitate to contact us.
In accordance with Section 170.12 of the Commission's regulations, enclosed is Philadelphia Electric Company's check in the amount of $150.00 to cover the filing fee for this request for approval.
Sincerely,
/
k ARP/pdO1158705 Copy to:
Dr. T. E. Murley, Administrator, Region I, USNRC T. P. Johnson, Resident Site Inspector