ML20079D363
| ML20079D363 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 07/03/1991 |
| From: | Cottle W ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GNRO-91-00110, GNRO-91-110, NUDOCS 9107110264 | |
| Download: ML20079D363 (8) | |
Text
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5 W. T. Cottle July 3. 1991 U.S. Nuclear Regulatory Commission liall Station P1-137 Washington, D.C.
20555 Attention:
Document Control Desk 1
Subject:
Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License Nc. NPF-29 ASME Section XI Pelief Request Number 1-0002? Revision 0 GNRO-91/00110 Gentlemen:
This submittal requests relief from the requirements of ASME Section XI, in accordance with 10CFR50.55a(g)(5)(iv) and 10CFR50.55a(g)(6)(i).
A copy of the request is attached.
Relief Request I-00022 Revision 0 identifies areas of the reactor pressure vessel (RPV) support skirt which are inaccessible for visual examination.
Access is blocked by removable and non-removable insulation. Relief is requested to exempt the inaccessiblo inside diameter of the RPV support skirt from visual examination.
The attachment provides support and justification for this request.
Your review and approval of these requests is requested prior to January 1, 1992, in order to allow planning for the upcoming refueling outage, which is scheduled for April 1992.
If additional information is required to support your review, please advise.
Yours truly, M r c%
kTC/JE0/mte attachment:
Relief Request Number I-00022 Revision 0 cc (See Next Page) 1
,,ftp106261/SNLICFLR - 1 f[lk$$$h M3N 6
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8
July 3,1991 GNRO-91/00110 Page 2 of 3 cc:
Mr. D. C. Ilintz (w/o)
Mr. J. L. Mathis (w/a)
Mr. R. B. McGehoe (w/o)
Mr. N. S. Reynolds (w/o)
Mr.11.
I.. Thomas (w/o)
Mr. F. W. Titus (w/a)
Mr. Stewart. D. Ebneter (w/a)
Regional Administrator U.S. Nuclear Regulatory Commission Region 11 101 Mariotta St., N.W.,
Sutto 2900 Atlanta, Georgia 30323 Mr.
l., l.. Kintner, Project Manager (w/a)
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 11D21 Washington, D.C.
20555 l
i i
G9106261/SNI,ICFLR - 2
Attachment I to GNRO-91/00110 Page 1 of 6 l
l Relief Request, Number 1-00022 Revision 0 "Inservico Inspect _lon Rf Reactor Pressure Vessel Support Skirt Surfaces" Pages Followl.ng:
5 Pnges Rollef Request - Revision 0 G9106261/SNLICFLR - 4
GRAND GULF NUCLEAR STAYION Inservice Inspection Requirements ectio INSERVICE INSPECTION
,g e
d TEN YEAR PROGRAM GRAND GULF NUCLEAR STATION UNIT 1 RELIEF REQUEST I-00022, REVISION O PAGE 1 OF 5 IHSR1VICE INSPECTION 9.E REACTOR E1WSSUillLY.EESE, SUPPORT _EKJRT rd!EEACES I.
Component:
Inaccessible surfaces of the Reactor Pressure vessel (RPV) Support Skirt, ASME Section XI Code Category F-A.
II.
Code:
The skirt is designed and fabricated as an integral attachment to the reactor pressure vessel. Additionally, the skirt is designed for and performs the function of an ASME Section III, Subsection NF component support. The reactor pressure vessel is
- designed, fabricated and certified to the 1971 Edition, Winter 1972 Addenda of ASME Section
- III, Subsection NB (Class 1).
III.
Code requirements:
ASME Section XI, 1977 Edition through the Summer 1979 Addenda, IWF-2500 requires supports of components chosen for examination under IWB, IWC, and IWD to be visually inspected (VT-3) in accordance with Table IWF-2500-1 and IWF-2500-2.
The ASME Section XI examination boundary includes both sides of the RPV skirt and extends from the support base plate / building structure connection to within one (1) bottom head thickness from the RPV head (Reference IWF-1300-1).
IV.
Information to The RPV support skirt is a cylinder that support the attaches at the RPV bottom head and determination that provides support for the vessel.
An the Code annulus area contained within the skirt requirements are is located between the bottom head and impractical:
the base foundation and contains numerous reactor pressure vessel components and their supports and snubbers. The vessel insulation is an all metal reflective type made up of combinations of two basic shapes; flat panels and curved panels.
The insulation for the vessel bottom
- head, along the vessel support skirt, consists of vertical curved panels 3
inches thick joined to form a cylinder.
M \\ME C H \\ HUN T E R \\R E L I E F S\\R R 22R OT X. 022
GRAND GULF NOCLEAR STATION Incervico Incpaction Rsquiremsnto 80CDIOD 4 INSERVICE INSPECTION N
TEN YEAR PROGRAM
~
l GRAND GULF NUCLEAR STATION a
1 UNIT 1 RELIEF REQUEST I-00022, REVISION O PAGE 2 OF 5 JySERVICE INSPECTION Of REACTOR PRESSURE VESSEL SUPPORT SKIRT S._t)RFACES IV.
Information to Panels extend along the entire inside support the surface of the support skirt up to the determination that beginning of the blend radius at the the Code support skirt to RPV bottom head requirements are attachment weld.
There is also a
impractical horizontal panel 3
inches thick which (continued):
connects across the bottom of the cylinder formed by the vertical insulation panels.
This panel is penetrated by the control rod drive
- housings, incore
- housings, core differential pressure nozzle, and drain nozzle.
This insulation is either designed as removable or permanent.
The removable insulation is installed with buckles and handles.
The permanent insulation is installed with a combination of sheet metal
- screws, bolts and rivets.
The insulation is located such that access for visual examination of the inside diameter (ID) of the support skirt surface and the ID support bolting is completely blocked.
Design information indicates that 28 insulation panels are removable:
1.
Four panels correspond to four access holes in the support skirt. Removal of these panels allows access ta the under-vessel area but exposes essentially no skirt surface for visual examination.
2.
Eight panels (four at 180 deg az and four at 0 deg az) provide access to.the two RPV drain areas.
Removal of these panels exposes approximately 27% of the ID support skirt to building structure bolting and approximately 2% of the ID skirt surface for 90 deg (45 deg per location) of skirt circumference.
Estimated time spent in removal and replacement of this insulation is 196 manhours.
Radiation dose rates are expected to average 150 millirem per hour. Man-rem exposure is estimated to be 29.4 rom.
M\\ MECH \\ HUNTER \\ RELIEFS \\RR22ROTX.022
! GRAND GULrt NUCLEAR STATION Inocrvica Inspection Rsquiremsnts-INSERVICE! INSPECTION Soction 4 TEN YEAR PROGRAM GRAND GULF NUCLEAR STATION UNIT 1 RELIEF REQUEST I-00022, REVISION,0 PAGE 3 OF 5 INSERVICE INSPECTION 9E REACTOR PRESSURE VESSEL SUPPORT SKIRT SURFACES IV.
'Information to 3.
Sixteen adjustable panels form a ring support the of insulation in the vessel to skirt weld determination that area. Removal of _ these panels exposes a the Code band of skirt base material in the IWF-re'quirements are examination boundary approximately impractical 22 1/2" wide.
' Based on experience (continued):
obtained during previous outages there is insufficient space to permit simultaneous removal of all panels unless they are completely removed from the skirt ID via the manways. Even though these panels are
" removable",
the top sections of the panels are screwed to the adjoining panels
-at 'the vertical split.line.
Removal of these panels exposes-approximately 30%_
of the ID skirt surface. Estimated time spent in removal
'and replacement of this insulation is 392 manhours.
Radiation dose rates are expected to-average 150 millirem per hour. Man-rem exposure is estimated to-be 58.8 rom.
4 Total estimated-man-rem exposure for removal and reinstallation of' all-removable-panels-is 88.2 rem. Access.to
'approxima_tely-27% of-the bolting and 32%
of the skirt surface is provided.
Removal of permanent insulation is required for -100% visual-examination.
' Estimated time spent in removal:- -- and -
replacement of. permanent insulation :is 882 manhours. Radiation dose rates are expected _ to.
average 150 millirem _per hour. Totali man-rem. exposure -' associated with removal-and-replacement of permanent.
insulation is estimated-to be 132.3 rem.
~
V.
, Specific relief Permission is requested to delete requested:
inservice inspection of the ID area of the RPV support-ski t.
M\\ MECH \\ HUNTER \\ ELIEFS\\RR22ROTX.022 R
GRAND GULF NUCLEAR STATION InOOrvico Incptction ROquircOOnto 80ction 4 INSERVICE INSPECTION est I'
TEN YEAR PROGRAM GRAND GULF NUCLEAR STATION UNIT 1 RELIEF REQUEST I-00022, REVISION O PAGE 4 OF 5 IliSERVICE INSPECTION DE REACTOR PRESSURE VESSEL SUPPORT SKIRT SURFACES VI.
Reasons why relief Deletion of the inservice inspection of should be granted:
the RPV support skirt ID is requested for the following reasons:
1)
All support skirt welds below the bottom head-to-vessel support skirt weld were required to be examined by the magnetic particle method in accordance with ASME III Class 1 requirements.
- 2) After completion of forming (rolling),
the final surfaces of the support skirt vertical members were required to be examined by the magnetic particle method in accordance with ASME III Class 1
requirements.
After completion of machining, the final surfaces of the support skirt base plate (flange) were required to be examined by the magnetic particle method in accordance with ASME III Class 1
requirements.
The final surfaces of the support skirt flange bolt holes were required to be examined by the dye penetrant method in accordance with ASME III Class 1 requirements.
- 3) The design basis failure mode of the support skirt is buckling caused by primary bending compressive
- r. tress.
Maximum permissible load is governed by buckling criteria.
The skirt vertical member is fabricated from SA533 Gr B Cl I plate.
This material has a
minimum required elongation of 18%. The percent strain resulting from forming is approximately 1.6%
(NB-4213.1).
After
- forming, the material still has ample ductility and is expected to exhibit significant plastic deformation prior to fracture.
Any service induced damage would be associated with buckling failure and would be evident during visual examination of the skirt exterior.
No aciditional information is obtained by an ID skirt exam.
l M\\ MECH \\HUNi[R\\ RELIEFS \\RR22ROTX.022
-.. -, ~. ~
iGRAND GULF NUCLEAR' STATION;
.Incorvico Incpoction Rsquiremonts
',f [
INSERVICE INSPECTION Section 4 Relief Request-IEN YEAR PROGRAM
==
GRAND GULF: NUCLEAR STATION
. UNIT 1.
RELIEF REQUEST I-00022, REVISION O-PAGE 5 OF 5 INSERVICE INSPECTION
_O_E I
REACTOR PRESSURE VESSEL SUPPORT SKIRT SURFACES VI.
Reasons why relief 4)
All support skirt base' and - weld should.be granted materials were procured in compliance (continued):-
with ASME;III ND-2300 to assure adequate
. protection against non-ductile failure.
Skirt base ~ material-was required--to exhibit-a reference--
nil-ductility transition temperature of -not greater than 10.-dog F as established by.Charpy V-notch and; dropweight tests.
For weld material',-
a reference nil-ductility transition' temperature of not greater than.-20 dog F was required. Rapid crack propagation _ from service conditions is unlikely..
S) 100% of the. external-skirt surfaces and bolting are-subject to ; visual examination once-every ten year-_ interval in accordance.with ASME XI.
VII.
Alternate' Testing:
None-VIII.
NRC discussion 4
statement:
1.
k I
f:
i M\\ MECH \\ HUNTER \\ RELIEFS \\RR22ROTX.022
.