ML20056F420
| ML20056F420 | |
| Person / Time | |
|---|---|
| Issue date: | 07/01/1993 |
| From: | Richardson J Office of Nuclear Reactor Regulation |
| To: | Rasin W NUCLEAR ENERGY INSTITUTE (FORMERLY NUCLEAR MGMT & |
| References | |
| GL-92-01, GL-92-1, NUDOCS 9308270199 | |
| Download: ML20056F420 (3) | |
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Mr. William H. Rasin i
Vice President and Director Technical Division Nuclear Management and Resources Council 1776 Eye Street NW, Suite 300 Washington, DC 20006-3706
Dear Mr. Rasin:
By letter dated March 16, 1993, NUMARC submitted a report prepared by l
Westinghouse for the Westinghouse Owners Group (WOG). er. titled " Reactor Vessel Upper Shelf Energy Bounding Evaluation for Westinghouse Pressurized Water Reactors" (WCAP 13587). The report was provided to NRC as supplemental information-in response to GL 92-01.
No review and approval was requested.
l This report is intended to demonstrate through. fracture mechanics analyses that there exists margins of safety against fracture equivalent to.those required by Appendix G of ASME Code Section III, for those beltline materials j
having upper shelf energy values below the screening criteria of 50 ft-lbs.
l The Materials and Chemical Engineering Branch, with assistance from the Office of Research has completed a preliminary assessment of this report and is transmitting a request for additional information (RAI).
In order to complete -
l our assessment, we request a response to the enclosed RAI within 30 days of receipt.
If you have. any questions, 'please contact Ed Hackett of my staff at 301-504-2751.
i Sincerely, Originalsigned by James E. Richardson, Director 1
L Division of Engineering Office of Nuclear Reactor Regulation
Enclosure:
As stated l
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ENCLOSURE i
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REQUEST FOR ADDITIONAL INFORMATION ON WCAP-13587, " REACTOR VESSEL UPPER SHELF I
J ENERGY B0UNDING EVALUATION FOR WESTINGHOUSE PRESSURIZED WATER REACTORS" i
(1)
Executive Summary, Page 11 - The summary states that a total of 43 vessels were included in the evaluation. - The letter from D.J. Modeen (NUMARC) to J.E. Richardson dated January 21, 1993 lists only 42 vessels j
covered by the WOG. Which is the correct number?
(2)
Criteria Synopsis, Page 1 For level A and B conditions it is stated, "If the base metal is governing, the postulated flaw must be axially oriented." The ASME Code Case states ".... for the base metal, i
postulate both interior axial and circumferential flaws...." Although the axial flaw case should be limiting, were circumferential flaws i
j considered as required by the Code Case?
(3) 2.1 Background, Page 2 The text states that ".... plants 5,14, 15 and 17 have upper shelf energy values of less than 50 ft-lbs during service life.". Table 2-1 shows that the E0L USE values for' plant 17 are all above 50 ft-lbs while 49 ft-lbs is shown for plant 16. Are the values tabulated correctly?
(4) 2.3 and 2.4 Mechanical Properties and Stress-Strain Curve, Page 2
- Minimum mechanical properties for RPV materials at 600 F were used as j-per the ASME Code. The intent was to bound all of the participating plants. However, no mechanical property data was provided for the j
individual plants to determine if this is a " bounding" approach.
Provide values of yield strength, ultimate strength and ductility for the materials from each vessel.
(5) 2.5 J-R Curves, Page 2 The text states that the NUREG/CR-5729 correlations are " material-independent." This statement is not entirely true as A302 Gr B data was specifically excluded from database used to develop the correlations. Hence, the correlations are not meant to apply to A302 Gr B.
(6) 2.5 J-R Curves, Page 2 The text states that the J-R_ curves were developed from the NUREG/CR-5729 correlations using a temperature of 390.5 F which " represents the greatest temperature at the crack tip for a 1/4t flaw" for level A and B conditions. As this results in a very large temperature differential across the vessel wall and is non-conservative for the J-R curve correlation, additional justification for use of this temperature is required.
Why are the J-R curves not determined using 600 F as was done with the mechanical properties?
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