ML18153C231
| ML18153C231 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 05/21/1990 |
| From: | Buckley B Office of Nuclear Reactor Regulation |
| To: | Stewart W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| References | |
| NUDOCS 9005290218 | |
| Download: ML18153C231 (5) | |
Text
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e UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 May 21 7 199.0.
Mr. W. L. Stewart Senior Vice President - Nuclear Virginia Electric and Power Company 5000 Dominion Blvd.
Glen Allen, Virginia 23060
Dear Mr. Stewart:
SUBJECT:
SURRY UNIT 1 -
LOW UPPER SHELF MATERIAL IN REACTOR VESSEL BELTLINE The purpose of this letter is to inform you of staff concerns for plants such as Surry, Unit 1, having reactor vessel beltline materials that have (or soon will have) below 50 ft-lbs upper shelf energy.
Elastic plastic fracture mechanics technology has advanced to a point that the criteria being written for the ASME Code are acceptable for regulatory use.
Certain actions are required to meet the requirements of 10 CFR Part 50, Appendix G, when the vessel materials fall below 50 ft-lbs.
Paragraph IV.A.! states, in part:
11 Reactor vessel beltline materials must have Charpy upper-shelf energy of no less than 75 ft-lb (102J) initially and must maintain upper-shelf energy throughout the life of the vessel of no less than 50 ft-lb (68J), unless it is demonstrated in a manner approved by the Director, Office of Nuclear Reactor Regulation, that lower values* of upper-shelf energy will provide margins of safety against fracture equivalent to those required by Appendix G of the ASME Code.
11 And, Paragraph V.C governs when the 50 ft-lb requirement is no longer met.
It states, in part:
11 *** reactor vessels may continue to be operated provided all of the following requirements are satisfied:
- 1.
A volumetric examination of 100 percent of the beltline materials that do not satisfy the requirements of Section V.B of this appendix is made and any flaws characterized according to Section XI of the ASME Code and as otherwise specified by the Director, Office of Nuclear React~r Regulation.
- 2.
Additional evidence of the fracture toughness of the beltline 1
- 3.
materials after exposure to neutron irradiation is to be obtained from results of supplemental fracture toughness tests.
An analysis is performed that conservatively demonstrates, making appropriate allowances for all uncertainties, the existence of equivalent margins of safety for continued operation.
11
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Mr. W. Stewart 2 -
May 21, 1990 The enclosed criteria are for your use and are the ones sent to us by the Chairman of the ASME Subgroup, Evaluation/Standards on November 20, 1989, with one modification, which we believe will appear in the Code.
The pressures are given in terms of P-acc, the 11accumulated pressure, 11 a term that comes from Section Ill, paragraphs NB~7311 and NB-7410, which require that the set pressure for expected system pressure transient conditions shall be such that the 11total accumulated pressure 11 shall not be more than 10% above the design pressure.
By basing the criteria on P-acc, use of the reduced operating pressure is permissible provided the pressure relief devices are set to correspondingly lower pressures.
For the nominal case, P-design is 2500 psig, P-operating is 2250 psig, and P-acc is at its maximum value of 1.10 P-design or 2750 psig.
The factors of 1.15 and 1.25 P-acc for the two criteria would call for pressures of 3162 and 3437 psig, respectively.
These are maximum pressures for P-design equal to 2500 psig.
The actual values will depend on the value of accumulated pressure given in the Overpressure Protection Report (NB-7200).
The NRC staff will prepare some guidance defining the credibility of J-R curves that are representative of the vessel material toughness, and defining what is meant by a 11conservative bound to J-Lia data 11 in the last sentence of the enclosed criteria statement.
Until that guidance is prepared you should consult with the NRC staff as you proceed.
Finally, we take this opportunity to remind you that one of the requirements of Appendix G is a volumetric examination of 100 percent of the beltline materials that do not meet the 50 ft-lbs requirement.
Within 60-days of receipt of this letter, please provide your plan for submitting the required fracture mechanics analysis and for performing the volumetric examination.
Should you require additional information on this matter, please call Dr. Cheng (301-492-0910) Chief, Materials and Chemical Engineering Branch.
The reporting and/or recordkeeping requirements contained in this letter affect fewer than 10 respondents; therefore, 0MB clearance is not required pursuant to P.L.96-511.
Enclosure:
As stated cc w/enclosure:
See next page L~P I-2 D i o I\\ 90 Qib PM:\\PDII-2 BBuckley:jkd os11i /90 Sincerely, Original stgned by Bart C. Buckley, Senior Project Manager Project Directorate II-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation fd!fll EMCB:~N~
CYChe 05/(g,'90 D:lt~
HB~r~w 05/J)/90 OFFICIAL RECORD COPY Document Name:
SURRY 1/LTR.
e Mr. w. L. Stewart Virginia Electric and Power Company cc:
Michael W. Maupin, Esq.
Hunton and Williams Post Office Box 1535 Richmond, Virginia 23212 Mr. Michael R. Kansler, Manager Surry Power Station Post Office Box 315 Surry, Virginia 23883 Senior Resident Inspector Surry Power Station U.S. Nuclear Regulatory Commission Post Office Box 166, Route 1 Surry, Virginia 23883 Mr. Sherlock Holmes, Chairman Board of Supervisors of Surry County Surry County Courthouse Surry, Virginia 23683 Mr. W. T. Lough Virginia Corporation Commission Division of Energy Regulation Post Office Box 1197 Richmond, Virginia 23209 Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta Street N.W., Suite 2900 Atlanta, Georgia 30323 C. M. G. Buttery, M.D., M.P.H.
Department of Health 109 Governor Street Richmond, Virginia 23219 Surry Power Station Attorney General Supreme Court Building 101 North 8th Street Richmond,_Virginia 23219 Mr. E. Wayne Harrell Vice President - Nuclear Operations Virginia Electric and Power Company 5000 Old Dominion Blvd.
Glen Allen, Virginia 23060 Mr. J. P. O'Hanlon Vice President - Nuclear Services Virginia Electric and Power Company 5000 Old Dominion Blvd.
Glen Allen, Virginia 23060 Mr. R. F. Saunders Manager - Nuclear Licensing Virginia Electric and Power Company 5000 Old Dominion Blvd.
Glen Allen, Virginia 23060
I...
e ENCLOSURE LOW UPPER-SHELF CRITERIA Level A and B Condit;ons For a postulated semi-elliptical surface flaw with a/t
- 0.25 and with an aspect ratio of 6 to 1 surface length to flaw depth, and oriented along the weld of concern, two criteria must be satisfied as described below. Smaller flaw sizes may be used on an individual case basis if a smaller size of the above postulated flaw can be justified.
- 1.
The crack driving fore~ must be shown to be less than the material toughness as given below:
J applied< Jo.1 (1) where J is the J-integral value calculated for the postulated flaw undi~P~teisure and thermal loading where the assumed pressure is 1.15 times accumulated pressure, and thermal loading using the plant specified heatup and cooldown condit;ons. The parameter J is the J-integral characteristic of the material resistance to dugt\\le tear;ng (Jmat~ria 1). as. usua-~1y denoted by a J1-R curve test, at a crack ex-tens ion of 0.1 inch.
- 2.
The flaw must be stable under ductile crack growth as given below:
dJapplied ~ dJmaterial
{2) da da at Japplied
- Jmateria1 where J
- 1s calculated for the postulated flaw under pressure and thermal loadinga~8~1ii1 service level A and 8 conditions where the assumed pressure fs 1.25 times accumulated pressure, and*thermal loading, as defined above.
The J-integral resistance versus crack growth curve shall reflect a conservative bound to J-Aa data representative of the vessel material under evaluation.
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DISTRIBUTION Docket File NRC & LPDRs PD22 Rdg Fi 1 e SVarga 14/E/4 GLainas 14/H/3 HBerkow DMiller BBuckl.ey OGC EJordan MNBB-3302 CYCheng 9/H/15 MSinkule RII ACRS (10)