ML20063N765
| ML20063N765 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 10/01/1982 |
| From: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| To: | Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| References | |
| REF-SSINS-6820, RTR-REGGD-01.065, RTR-REGGD-1.065 IEB-82-02, IEB-82-2, NUDOCS 8210070159 | |
| Download: ML20063N765 (3) | |
Text
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,n BALTIMORE GAS AND ELECTRIC CHARLES CENTER P.O. BOX 1475. BALTIMORE, MARYLs ND 21203 October 1,1982 ARTHUR E. LUNOVALL, Jm.
VICE Puts
- DENT SUPPLY
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U.S. Nuclear Regulatory Commission Office of Inspection & Enforcement Washington, DC 20555 ATTENTION:
Mr. Richard C. DeYoung, Director SUB3ECT:
Calvert Cliffs Nuclear Power Plant Unit Nos.1 & 2; Docket Nos. 50-317 & 50-318 Reactor Vessel Head Closure Stud Inspection Requirements
REFERENCES:
(a)
IE Bulletin 82-02," Degradation of Threaded Fastners in the Reactor Coolant Pressure Boundary of PWR Plants" (b)
Letter to R.
C.
Haynes from A.
E. Lundvall, Jr.,
dated July 30,1982 Gentlemen:
IE Bulletin 82-02 requires that certain additional examinations be performed on specific Reactor Coolant Pressure Boundary threaded fasteners. The bulletin excludes Reactor Vessel Closure Studs for licensees committed to the provisions of Ragulatory Guide 1.65,
" Materials and Inspection for Reactor Vessel Closure Studs." Although Calvert Cliffs-Units 1 and 2 are not committed to follow Regulatory Guide 1.65, we feel the intent has been met and, therefore, are requesting approval of the exclusion for use at Calvert Clifis Nuclear Power Plant.
Regulatory Guide 1.65 provides information and guidelines for the design, inspection, and protection of reactor vessel closure stud bolting. Although exceptions exist for Calvert Cliffs bolting, these differer.ces are minor and consistent with the intent of the Regulatory Guide.
Calvert Cliffs reactor vessel bolting material is SA-540 GR B-24 CL3 and complies with the recommended materials of the Regulatory Guide. The measured ultimate tensile strength of this botting material f alls between 142.5 and 171.5 KSt. The Regulatory Guide recommends that ultimate tensile strength should not exceed 170 KSI to provide immunity to stress corrosion cracking (SCC).
The above mentioned stud material demonstrates that adequate tempering was performed to avoid high ultimate tensile strengths thus reducing the materials susceptibility to SCC.
Regulatory Guide 1.65 requires that Charpy V impact testing meet 10 CFR 50 Appendix G Paragraph IV.A.4 which specifies minimum requirements of 25 mils lateral expansion and 45 ft-lbs. in terms' of tests conducted at the preload or lowest service temperature, whichever is
-lower. Charpy V energy impact testing was performed on Calvert Cliffs reactor vessel bolting material' to demonstrate transition temperatures below 10 F.
Although tests were not performed at the preload or lowest service temperature, impact transition 8210070159 821001' PDR ADOCK 05000317 f..v eDR a
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Mr. Richard C. DeYomg October 1,1982 Page 2 curves show ductile transition takes place well below this temperature and adequate fracture toughness is provided. The lowest allowed preload temperature is 70 F for Calvert Cliffs, which is lower than service temperatures. Measured values of Charpy V impact tests for each " heat" of Calvert Cliffs reactor vessel bolting material show values for energy and lateral expansion at 10 F of 40 ft-lbs. and 19 mils,45 f t-lbs. and 26 mils, and 50 ft-lbs. and 28 mils.
The Calvert Cliffs reactor vessel studs, nuts, and washers are coated with an antigalling phosphate coating in accordance with manufacturing specifications as permitted by the Regulatory Guide. Lubrication of the bolting with Super-Moly 4064 complies with the n
recommended lubrication requirements.
Adequate prevention against corrosion is maintained through maintenance and inspection procedures. All studs are removed and plugs are installed in reactor vessel flange holes prior to refueling pool flooding as recommended by Regulatory Guide 1.65.
Manufacturing and Preservice Inspections exceeded the requirements of Regulatory Guide 1.65.
The studs and nuts received ultrasonic testing af ter tempering prior to threading. The studs and nuts also received a magnetic partical inspection before and af ter threading in accordance with ASTM E-138-63. In addition to the above inspections, preservice inspections were performed on 100% of the studs and nuts prior to commercial operation by Southwest Research Institute incorporating a new ultrasonic technique in which a transducer is lowered into the stud bolt center hole and an ultrasonic radial 60-degree shear wave scan is performed as recommended by the Regulatory Guide.
Inservice Inspection scheduling and testing also meets the requirements of the Regulatory Guide and ASME Code Section XI.
Inspection of 100% reactoi vessel head bolting every refueling outage would significantly add radiation exposure to inspection teams. It is estimated that forty (40) mrem are required to manipulate, inspect, and reclean each stud. This equates to 2,160 mrem per outage for 54 studs or 28.8 rem for two units every ten (10) years as opposed to about six (6) rem for ASME Code Section XI inspection requirements. A total added inspection personnel exposure of 22.8 rem every ten (10) years would be realized by following IE Bulletin 82-02 reactor vessel bolting inspection requirements should the Regulatory Guide 1.65 exclusion be disallowed. It is also estimated that it would require 4,000 man-hours of radiation-control, quality assurance, and inspection personnel every ten (10) years to perform the additional examinations.
This letter has been developed as the result of discussions with Mr. W. 3. Collins, Technical Contact, for IE Bulletin 82-02.
Unless otherwise notified, we expect to implement the Regulatory Guide 1.65 exclusion allowance contained in IE Bulletin 82-02 sixty (60) days from the date of this letter.
rc.
o Mr. Richard C. DeYoung October 1,1982 Page 3 Should you have further questions regarding this matter, we would be pleased to discuss them with you.
Very truly yours, A
A I
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By:
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"Vice President 2 Supply}
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cc:
- 3. A. Biddison, Esquire G. F. Trowbridge, Esquire W. 3. Collins, NRC D. H. Jaffe, NRC R. E. Architzel, NRC R. C. Haynes, NRC i
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