ML20127N218
| ML20127N218 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 11/25/1992 |
| From: | Zeringue O TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-88-01, GL-88-1, NUDOCS 9212010089 | |
| Download: ML20127N218 (7) | |
Text
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November 25, 1492 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk-Washington, D.C.
20555 Gentlemen:
In the Matter of
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Docket Nos. 50-259 Tennessee Valley Authority
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50-260 2
50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - REQUEST FOR NRC APPROVAL OF ALTERNATE METHODS FOR THE REACTOR WATER CLEANUP (RWCU) AND RESIDUAL 1: EAT REMOVAL (RHR) INSERVICE INSPECTIONS REQUIRED BY GENERIC LETTER 88-01
Reference:
1.
GL 88-01, "NRC Position on IGSCC of BWR Austenitic Stainless Steel Piping", dated January 25, 1988 2.- GL 88-01, Supplement dated February 4, 1992 3.
Letter from TVA to NRC dated May 22, 1989, "Browis Ferry Nuclear Plant-(BFN) - TVA's Response to NRC Inspection Report (IR) No. 89-05 on Generic Letter-88-01" 4.
Letter from TVA to NRC. dated April 14, 1992, " Browns-Ferry Nuclear Plant (BFN) - Generic. Letter.(GL) 89-10 Safety..Related Motor-operated Valve Testing and Surveillance Impt ementation Scheduled-(TAC Nos. 75635, 15636, and 75637)"
5.-
Letter from TVA to'NRC dated August 1, 1988, BFN -
Response to-Ceneric Letter 88-01', NRC Position on IGSCC.
in BWR Austenitic Stainless Steel Piping (L44 880801 804) 6.
Letter from NRC to TVA dated August 26, 1987, " Technical Specification (TS 222) related to Reactor Coolant Leakage 50 01.7.(TAC 64372, 64373, 64374)"
-9212010089 921125-J PDR ADOCK 05000259 G-pop _
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3 U.,S. Nuclear Regulatory Commission November 25, 1992 The purpose of this submittal is to establish a position relative to actions required in Reference 1.
The specific items concern piping velds in the RWCU system (Enclosure 1) and a clarification of TVA's commitment to address inaccessible velds in the RHR system (Enclosure 2). contains the commitment summary.
TVA requests an expedited review of this letter in order to support a possible reduction in the scope of work required for the Unit 2 cycle 6 outage scheduled for January 1993.
If you have any questions, contact G. D. Pierce, Interim Manager of Site Licensing, at (205) 729-7566.
Sincerely, N/
/
0.;J. Zeringte Enclosures cc (Enclosures):
NRC Resident Inspector Browns Ferry Nucicar Plant Route 12, Box 637 Athens, Alabama 35611 Mr. Thierry M. Ross, Project Manager U.S. Piclear Regulatory Commission One White Plint, North 11555 Rockville Pike Rockvilla, Maryland 20852 Mr. B. A. Wilson, Project Chief U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323
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t ENCLOSURE 1 I
In Reference 2 NRC states that a reduced inspection scope is possible for RWCU piping wolds located outboard of the containment isolation valve due to high radiation levels.
Additionally, recent communicationa involving the Boiling Water Reactor Owners Group (BWROG) and the NRC indicates that eliminations of these weldments from the GL 88-01 inspectior scope is possible under certain circumstances if GL 89-10 actions on motor operated valve testing are completed, In Reference 3 TVA committed to replace all RWCU piping located outside the drywell on Units 1 and 3 prior to restart and to replace the same piping on Unit 2 during cycle 6 outage.
The present BFN status relative to RWCt1 pipe replacement and the implementation of GL 89-10 requirements is summarized as follows:
UNIT 1 - All RWCU piping exterior to the drywall will be replaced with IGSCC resistant material prior to restart.
GL-89-10 requirements Yill be implemented as stated in Reference 4.
UNIT 2 - All RWCU piping exterior to the drywell will be replaced with IGSCC resistant material during the next refueling outage (Cycle 6 outage). This is approximately one cycle j
before full implementation of GL 89-10 as stated in Reference 4.
UNIT 3 - All RWCU piping including that exterior to the drywell has been replaced with IGSCC resistant material.
GL 89-10 will be implemented as stated in Reference 4.
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By replacing the RWCU piping with IGSCC resistant material, the l
RWCU piping welds will be Cat 2 gory "A" weldments.
Per GL 88-01 requirements only 12 percent of Ca'agory "A" weldrents require IGSCC examination within a 6-year period.
Based on this inspection frequency the new replacement RWCU welds will not j
require inspection prior to completion of GL 89-10 requirements.
Due to TVA's commitment to replace RWCU piping and its planned implementation of GL 89-10 requirements, TVA requents NRC concurrence to remove'the RWCU welds located outboard of the containment isolation valve from the GL 88-01 inspection program scope.
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ENCLOSURE 2 i
RHR Inaccessible Welds GL 88-01 establiches inspection requirements for inaccessible welds which are as follows:
Welds that are not UT inspectable should be replaced,
" sleeved", or local leak detection applied.
RT examination 4
or visual inspection for leakage may also be considered.
Presently, each of the two RHR return penetrations (assemblies X-13A and X-138) have an inaccessible weld which has been determined to be within the scope of GL 88-01.
These welds are made with IGSCC susceptible material and therefore are currently classified Category "G" welds.
The welds are positiored within a sleeve guard pipe and are located approximately 13-ft from where i
the guard pipe opens into the drywell (see Figure 1).
A clearance of approximately 5.25" exists between the pcocess pipe and the guard pipe, which eliminates the ability to perform any e
direct physical examination of the weld.
TVA requests NRC concurrence that implementation of the following will meet tne requirements entablished in GL 88-01 for the l
subject inaccessible welds and will fulfill TVA's commitment stated in Reference 5 on t'.7e same subject.
1.
The insulation between the guard pipe and process pipe i
will be renoved to aid visual inspection of the subject weldments.
2.
During each refueling outage a system leakage test is performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code (Article IWB-5000).
Current practice entails pressurizi.ng the process pipe to greater than 500 psig while system walkdowns are conducted and systen test parameters stabilize.
This 4
condition is estimated to exist for a period in excess of eight hours.
Following completion of system walkdowns and stabilization of test parameters the process piping will be pressurized to a minimum of 1005 psig (normal reactor operating pressure).
A visual inspection of the process piping will be made from the drywell by examining the surrounding area (the penetration and the inaccessible weld area) for evidence of leakage.
3.
TVA has Technical Specification requirements in place which meet the leak detection requirements established in GL 88-01. (See Reference 6).
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i ENCLOSURE 2 (Continued)
The following information is relevant to approving this approach for these inaccessible welds.
1.
The process piping where the subject welds are located only experience greater than 200 degrees Fahrenheit 4
conditionti for a short period of time during shutdown cooling operations.
This significantly reduces the i
probability for IGSCC to occur.
2.
Inspections of welds in the section piping between the 4
inaccessible weld and the first isolation inside the drywell have not revealed indications of IGSCC on Unito 2 and 3, Both these units have received recent UT examinations using automated UT techniques and weld profile. enhancement.
Unit I has one pipe weld with indications in each section of piping between the inaccessible weld and the first isolation valve inside containment.
The Unit 1 pipe welds were last inspected in 1983 with manual UT techniques without the aiu of weld profile enhancement.
TVA's experience with early 1983 vintage manual techniques without weld profile 1
enhancement is that indications miscalls are more probable as compared to modern automated techniques with 4
weld profile enhancements, i
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ENCLOSURE 3 2
i COMMITMENT SUliMARY 4
1.
The insulation between the guard pipe and proceas pipe will be removed to aid visual inspections of the RHR inaccessible welds.
2 2.
Each refueling outage a visual inspection of the process piping will be made from the drywell by examining the surrounding area (the penetration and the inaccessible weld area) for evidence of leakage.
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FIGURE 1.
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RES DUAL -iEA~~ REMOVAL PE\\ E" 9ATION DETAILS (X13A & B) i l
DRYWELL REACTOR BUILDING
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THE INSULATION CURRENTLY IN PLACE l
WILL BE REMOVED TO FACIOTATE V!SUAL IDENTIFICATION OF LEAKS.
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