ML20079R771

Updates Status of BAW-1784 Re Internals Bolting Repair Activities.B&W Stress Analysis Plus Margins Afforded by Util Repair Plans,Assure Safety of Reactor Internals for Return to Full Power

ML20079R771
Person / Time
Site:	Crystal River
Issue date:	06/20/1983
From:	Westafer G FLORIDA POWER CORP.
To:	Stolz J Office of Nuclear Reactor Regulation
References
3F-0683-10, 3F-683-10, TAC-51556, NUDOCS 8306240259
Download: ML20079R771 (5)

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C O R P o m a , s o as June 20,1983 3F-0683-10 Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz, Chief Operating Reactors Branch No. 4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 Reactor Internal Bolting

Dear Sir:

The purpose of this letter is to update the status of the Florida Power Corporation (FPC)

Internals bolting repair activities at the Crystal River Unit 3 (CR-3) reactor. Our lost status letter was sent on May 20, 1983, to the Director of Nuclear Reactor Regulation, Attention: Mr. John F. Stolz. Additional information was provided at the briefing for NRC by the B&W Owners Group (BWOG) on May 6,1983, and by the Owners' summary report (BAW 1784) transmitted to the NRC on May 20, 1983. We will also update those portions of BAW 1784 opplicable to CR-3 which worront revision based on information obtained since May 20, 1983. We understand that information in this letter will be utilized by the Nuclear Regulatory Commission (NRC) in completing a Safety Evoluotion Report (SER) scheduled for issuance on June 24,1983, on the internals holting problem.

The following repair activities are completed at CR-3 as of June 17, 1983: All 96 thermal shield bolts have been replaced with inconel X-750 stud / nut fosteners; the upper core barrel bolts have been replaced with improved A-286 bolt design, fabrication, and torqueing techniques; and partial replacement of the surveillance specimen holder tube (SSHT) bolts is completed.

An analysis has been performed which shows that on SSHT assembly con withstand normal and anticipated transients with a minimum of two bolts per upper and lower restroint block. Support from the middle bracket is not required. The repair work is intended to provide at least three good (no ultrasonic flow indicottons) fosteners per upper and lower bracket although most brackets will still have four. The replacement SSHT fosteners are a stud / nut design made of Inconel X-750.

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8306240259 930620 d U <

-PDR ADDCn 05000302 P PDR l General Office 3201 Thirty iourtn street soutn . P O. Box 14042, st. Petersburg. Florida 33733 813-866-5151

l Director of Nuclear Reactor Regulation 3F-0683-10 Page 2 - i With respect to the updating of BAW 1784 based on information obtained since May 20, 1983, the enclosures provide current information for CR-3.

We_ hope that this letter will complete the information needed by the NRC on the internals bolting problems, analyses, repairs, and plans for CR-3. It is our judgement that the stress analysis (performed by Babcock and Wilcox, affirmed by MPR, and reviewed by FPC) plus the margins afforded by our repair plans, give assurance that the reactor internals at CR-3 are suitable for return to full power operation.

Sincerely,

, M G. R. Westafer Manager Nuclear Licensing and Fuel Management Enclosures (3)

ED/LBT:mm cc: R. Hernon U. S. Nuclear Regulatory Commission Washington, D.C. 20555 S. Miner

- U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Mr. James P. O'Reillly Regional Administrator, Region 11 U. S. Nuclear Regulatory Commission Atlanta,'CA 30303

Enclosure i Update of BAW 1784 for CR-3 Ultrasonic Flaw Indications / Bolts Examined 5/6/83 6/17/83 Surveillance Holder Tube 25/72 20/72 Lower Thermal Shield 73/96 74/96 69 Heads 71 Heads Twisted off Twisted off NOTE: Ultrasonic Flaw' Indication changes from 5/6/83 to 6/17/83 result from odditional measurements and/or interpretations.

Enclosure 2 Table D-1 (1)

Stress Levels for CR3 Internals Bolting Cycles 1-4 (2)

Nominal Nominal Stress Preload Operating Total Concentration Peak Stress Stress Stress Factor Stress Boltino Location (KSI) (KSI) (KSI) (KT) (KS1)

Upper Core Barrel 36.5 5 41.5 2.99 124 Lower Core Barrel 28. 8 36 2.99 108 Upper Therma: Shield 20 3 23 2.27 52 Flow Distributor 33 2 35 2.34 82 Lower Thermal Shield 33- 32 65 2.45 159

~ (Initial Installation)

Surveillance Holder Tube 45 3 48 2.62 126 Yield stress of A-286 varies from 100 to 134 KSI. Preload stress values based on neolube.

(1) Excerpts from B&W letter to NRC dated 6/7/83, Taylor To Miner.

(2) Values in this column were applicable to bolt head-to-shank transition region.

J Enclosure 3 Stress Levels for CR-3 Internals Bolting Cycle 5 Nominal Nominal Stress Preload Operating Total Concentration Peak Stress Stress Stress Factor Stress Bolting Location (KSI) (KSI) (KSI) ~ (KT ) (KT)

Upper Core Barrel 18.5 4.1 22.6 3.45 78

.Lcwer Core Barrel 28 8 36 2.99 108

' Upper Thermal Shield 20 .3 23 2.27 52 Fl:w Distributor 33 2- 35 2.34 82 Lcwer Thermal Shield 28.5 26.8 55.3 (l) (l)

Surveillance Holder Tube 30 14 44 (I) (l)

(1) Not applicable - Stud / Nut Fostener has no head-to-shank transition region.