ML20138H978
| ML20138H978 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 04/29/1997 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9705070353 | |
| Download: ML20138H978 (4) | |
Text
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Etriton Support Depirtment 4
l 10 CFR 50.55a(g)(6)(ii)(A)(5)
PECO NUCLEAR nco e-c-A Unit of PECO Energy Via P 1 75 1 April 29,1997 Docket No. 50-278 License No. DPR-56 i
U.S. Nuclear Regulatory Commission Attn: Document Control Center Washington, DC 20555 i
Subject:
Peach Bottom Atomic Power Station, Unit 3
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Alternative Plan in Accordance with 10 CFR 50.55a(g)(6)(ii)(A)(5)
Reference 1.
Letter from G. A. Hunger, Jr. (PECO Energy Company) to U. S.
Nuclear Regulatory Con. mission (USNRC), dated January 30, 1997 2.
Letter from J. W. Shea (USNRC) to G. A. Hunger, Jr. (PECO Energy Company), dated March 26,1997 Dear Sir in accordance with 10 CFR 50.55a(g)(6)(ii)(A)(5), PECO Energy Company (PECC Energy) submitted an alternative plan for the examination of the Peach Bottom Atomic Power Station (PBAPS), Unit 3 Reactor Pressure Vessel (RPV) shell welds in the Reference 1 letter. In response to this plan, the U. S. Nuclear Regulatory Commission (USNRC) has requested additional information as discussed in the Reference 2 letter.
Attached is our response to this request.
If you have any questions, please contact us.
Very truly yours,
.N.
1 G. A. Hunger, Jr.,
Director Licensing Section uh$hkkh,I!!t g.
Attachment cc:
H. J. Miller, Administrator, Region I, USNRC W. L. Schmidt, USNRC Senior Resident inspector, PBAPS 970507o353 970429 PDR ADOCK 05 28 P
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i Response to Request For Additional information for Peach Bottom Atomic Power Station, Unit 3 Concerning the Reactor Pressure Vessel Alternative Examination Plan l
Reauest No.1 s
" Identify each weld in item B1.10 of Examination Category B-A with estimated volumetric examination coverage to be obtained by an Inner Diameter (ID) examination. Discuss physical constraints inside the vessel, such as, removable internals, permanent attachments to vessel wall that obstruct scanning of the 3
shell welds to obtain the required volumetric examination cove age."
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Response No.1 Table 1 provides the welds, the estimated volumetric examination coverage from the ID, and the ID restrictions that will potentially obstruct scanning. The volumetric examination coverage and restrictions from the ID are based on a J
detailed weld coverage scan plan completed in April,1997. As shown in Table 1,11 of 20 welds achieve greater than 90% volumetric coverage from the ID only. There are no vessel intemals which pose a restriction to the ID examination which are easily removable. The only removable components (i.e.,
not welded to the vessel which limit scan coverage) are the feedwater spargers.
However, it is impractical to remove the feedwater spargers due to the potential 4
for damage to the sparger seals and nozzles. Therefore, there are no components which can be removed to in'.rease coverage from the ID.
Reauest No. 2
" Provide an estimate of increase in examination coverage of each weld when supplemented by an Outer Diameter examination. Also, discuss physical constraints, if any, that would obstruct manual and/or mechanized scanning of the above welds from the outside surface of the vessel to supplement the ID examination to obtain the required volumetric coverage."
Response No. 2 For those welds where greater than 90% volumetric examination may not be achieved from the ID, the estimated supplemental coverage and physical constraints on the vessel Outer Diameter (OD) are identified in Table 1. As noted in Table 1, further review has determined that one (1) weld (RPV-V1 A) would exceed 90 perce * 'olume coverage with a supplemental OD examination.
In some locations, the additional weld volume that can be accessed from the OD is a subset of the ID examinations.
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1 The restrictions which prohibit unrestrained access to 100% of the weld volume from the OD include; 1) vessel insulation, 2) vessel nozt.q, and 3) convection i
stops.
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The percentage of weld vmome coverage estimated from the ID exaraination reflects a significant portion of the total reactor pressure vessel weld length, with essentially 100% of the weld length in the beltline region being examined.
Attempting to perform supplemental OD examinations will result in a minimal increase to weld volume coverage. Obtaining this additional coverage will only j
permit one additional weld to exceed the 90% volumetric coverage requirement.
Additional disassembly and reassembly of portions of the reactor vessel biological shield and insulation would result in further increases in personnel radiation exposure of laborers and technicians assigned to these tasks as well i
as an increase in the general area dose rates in the Drywell for the entire j
population of workers. Additional doses to the entire population to perform the j
supplemental examinations contained in Table 1 are estimated to be 24 man-Rem. In order to perform the OD examinations, an estimated cost of approximately $460,000, beyond the cost of performing the ID examinations, L
would be incurred. Therefore, performing OD examinations to increase examination coverage beyond that achieved from the ID would result in undue 4
hardship without a compensating increase in safety.
Reauest No. 3 i
" Provide dimensions of the largest indication (planar and/or linear) in each of the welds accepted during the preservice and the subsequent inservice inspection."
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Response No. 3 l
The PSI and ISI examination summaries were reviewed to identify planar and/or l
linear indications and are listed in Table 1. Additionally, during fabrication, slag i
and porosity indications were identified and are also included in Table 1. All indications in Table 1 were code acceptable.
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l TABLE 1 RESPONSE TO REQUEST FOR ADDTIONALINFORMATION REACTOR PRESSURE VESSEL ALTERNATIVE PLAN PBAPS, UNIT 3 NWNf76RFBli3sIVsfDbTfWstiliG6sisDUWFil788finaliisiil6HT4 RPV-V1A 83.4 %
SSBP, JPRE, 10%
1,NOZ NONE NOZ 4
RPV-V1B 83.4 %
SSBP, JPRE 0%
1,NOZ NONE RPV-V1C 83.4 %
SSBP, JPRE 0%
1,NOZ 3" Diameter Laminar RPV-V2A 97.7%
JPRB N/A N/A Clad Indications RPV-V2B 100 %
N/A N/A N/A NONE RPV-V2C 97.7%
,JPRB N/A N/A NONE RPV-V3A 100 %
'N/A N/A N/A NONE RPV-V3B 100 %
N/A N/A N/A NONE RPV-V3C 81.8 %
CSDC 8%
1 NONE RPV V4A 70.9%
CSP, FWS, NOZ 0%
1 NONE RPV-V4B 70.1 %
CSP, FWS 0%
i NONE RPV-V4C 73.9%
CSP, FWS 0%
l NONE RPV-VSA 92.5 %
SDB N/A N/A NONE RPV-V5B 100 %
N/A N/A N/A NONE RPV-V5C 100 %
N/A N/A l
NONE RPV-C1 0%
SSBP 15%
1, NOZ, CS 12" Long Laminar Porosity
- RPV-C2 97.8 %
GR, SB N/A N/A NONE RPV-C3 97.8 %
GR, CSDC, NOZ N/A N/A Spot Laminars RPV-C4 83.8 %
GR, CSDC, NOZ 5%
i Slag
- RPV-C5 95.5 %
GR, NOZ N/A N/A NONE Abbreviations:
SSBP - Siiroud Support Baffle Plate GR - Guide Rod CSDC - Core Spray Downcomer NOZ-Vessel Nozzle JPRE - Jet Pump Riser Elbow JPRB - Jet Pump Riser Brace CSP - Core Spray Pipe FWS - Feedwater Sparger SDB - Steam Dryer Bracket I-Insulation SB - Specimen Brackets CS - Convection Stops N/A-Not Applicable
- Identified during fabrication 3