ML20082B045
| ML20082B045 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 03/28/1995 |
| From: | Carns N WOLF CREEK NUCLEAR OPERATING CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| WM-95-0049, WM-95-49, NUDOCS 9504040345 | |
| Download: ML20082B045 (10) | |
Text
_
i W$LF CREEK 1
NUCLEAR OPERATING CORPORATION
- Ned S.
- Bun" Carns March 28, 1995 Chairman, President and cruef Enecutiveottoer WM 95-0049 l
l U.
S.
Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-137 Washington, D. C.
20555
Subject:
Docket No. 50-482:
Inservice Inspection Program Relief Requests IIR-40 through IIR-44 Gentlemen:
This letter transmits requests for relief from ASME Section XI requirements for the Wolf Creek Generating Station Inservice Inspection (ISI) Program in accordance with 10 CFR 50.55a (g) (5) (iii).
Provided in the attachment to this e
letter is a portion of the relief requests that apply to ISI Period' 3.
Additional relief requests associated with ISI Period 3 may be submitted in the future dependent upon reviews of relief requests previously denied by the NRC.
Relief Request IIR-40 concerns the requirement to perform a visual examination of the internal surfaces of Code Class 1 valves.
Relief Requests IIR-41 tid I1R-42 concern the obstruction of welds that prevent complete examinations.
Relief Request I1R-43 and I1R-44 concern incomplete examinations as a result i
of the component geometry and metallurgic properties.
If you should have any questions regarding this submittal, please contact me at (316) 364-8831, extension
- 4000, or Mr.
Richard D.
Flannigan at extension 4500.
Very truly yours, 1
- W Neil S.
Carns NSC/jra Attachment cc:
L.
J.
Callan (NRC), w/a r
D.
F.
Kirsch (NRC), w/a J.
F.
Ringwald (NRC), w/a i
J.
C.
Stone (NRC), w/a P O. Box 411/ Burlington KS 66839 / Phone- (316) 3f,4-8831
(
j 9504040345 950328 gDR ADOCK 05000482
^""""'
(
\\D q
\\
^
\\
Attcchm2nt to WM 95-0049 i
P gy 1 o[ 9 ISI RELIEF REQUEST IIR-40 comnenent:
1 EJ-04-BB-PV8702A(&B)-SURF, Reactor Coolant System to Residual Heat Removal Pump Suction Isolation Valves EJ-04-HV-8701A(&B)-SURF, Reactor Coolant System to Residual Heat Removal Pump Suction Isolation Valves BB-02-8010A(B&C)-SURF, Pressurizer Safety Valves category:
ASME Section XI, 1980 Edition, Winter 1981 Addenda, Table IWB-2500-1, Examination Category B-M-2, Item Number B12.50
==
Description:==
Internal surfaces of Code Class 1 valves greater than 4 inches nominal pipe size code Requirement:
Table IWB-2500-1, Category B-M-2, Item Number 12.50 requires that a visual examination (VT-3) of the internal surfaces of one Code Class 1 valve within a group of system valves that are of the same constructional design, manuf acturing method and function, be performed each interval.
Basis for Relief:
Because these examinations must be performed whether or not the valves have to be disassembled for maintenance, this requirement is considered impractical.
The requirement to disassemble primary system valves for the sole purpose of performing a VT-3 of the internal pressure boundary surfaces has only a very small potential of increasing plant safety margins and a very disproportionate impact on expenditures of plant manpower and radiation exposure, which has been conservatively estimated to be approximately 30 Man-Rem.
A more practical approach which would provide an equivalent sampling program and significantly reduced radiation exposure to plant personnel is to examine the internal pressure boundary of only those valves that require disassembly for maintenance purposes. This would still provide a reasonable sampling of the primary system valves and give adequate assurance that the integrity of these components is being maintained.
This approach is supported by ASME Section XI, 1989 Edition, which is approved for use in 10 CFR 50.55a.
Alternate Examination:
VT-3 of the internal pressure boundary surf aces will be performed, to the extent practical, when a valve is disassembled for maintenance purposes.
=Att chment to WM 95-0049
..P:gy 2 of 9 Evaluation of plant Safetyr The performance of both carbon and stainless cast valve bodies has been excellent in Pressurized Water R*::tmr applications.
Considering this experience in the industry and regulatory acceptance of these alloys, continued excellent performance is anticipated.
{
s
Attcchm:nt to WM 95-0049 Pige 3 of 9 ISI RELIEF REQUEST I1R-41 Component:
EP-02-R020 Category:
ASME Section XI, 1980 Edition, Winter 1981 Addenda, Table IWC-2500-1, Examination Category C-C, Item Number C3.20 De=cription:
Accumulator Safety Injection Loop 3, Integral Welded Attachment - B Lugs Code Requirement:
Requires that 100% of the weld length plus 1/2 inch of the base material shall have a surface examination.
Reference Figure IWC-2500-5 of ASME Section XI for surface examination requirements.
Basis for Relief:
Surface examinations of 4 out of 8 lugs were obstructed by a pipe support located adjacent to the lugs.
The obstructed weld length was approximately 5 inches (29.4 percent of the 17 inches total weld length) for each lug (reference Figure 1).
The obstructing support and subject lugs are located inside the bioshield of the Reactor Containment Building at a high elevation.
Because of this support's location and size, its removal would require an extensive work ef fort and exposure to personnel without a compensating increase in safety.
<ernate Examination:
None.
The required surface examination was completed to the maximum extent possible without the undue burden of support removal.
ASME Cosie Section III:
Components were accepted in accordance with the requirements of Section III, which included a surface examination as well as a pressure test.
Evaluation of Plant Safety:
Strict ASME Section III quality controls were used when designing, fabricating, and installing these welds.
No irregularities were found in the previous surface examination performed during Preservice Inspection activities.
In addition, the subject integral attachment is located on a system that is not required to operate during normal plant operating conditionn and remains flooded under static conditions until such time that it is required to perform its shutdown function.
Therefore, the probability of a service induced flaw being created is very small and reasonable assurance of continued inservice structural integrity is achieved.
L
I t-2 Attachment to hH 95-0049
.P;gp 4 ol 9 Support EP02.R020 a
s D'
ss s
N s
s s
N s
h j
Typical of 4 out of 8 lugs S
s 3
s N
t J
s Flow s
6,,
s 3
s 3
s 5
s s
D s
D s
N s
5 s
3 s
5 s
N s
5 s
N N
s 5,,
j s
1r s
5 w
' - l l l l l l l l l l l l l l l We.ld.. l. l..l.l.l. l.l.l.l. l.l.l.l. l..'.*.
s.
Obstructing lianger clamp Unable to examine 5" of weld per lug Total weld length per lug = 17" Total length oflimited exam = 20" (Drawing Not to Scale)
FIGURE 1 i
i
)
i
Attcchment to WM 95-0049 P gg 5 of'9 ISI RELIEF REQUEST I1R-42 componenti EJ-02-S035-D-LU Category!
ASME Section XI, 1974 Edition, Summer 1975 Addenda, Table IWC-2520, Examination Category C-F Description Residual Heat Removal Train "B",
10 inch pipe longitudinal seam upstream code Recuirement,1 The angle beam examination for reflectors transverse to the weld (parallel scan) shall be performed on the weld to examine the weld root by 1/2 V path in two directions as specified by Appendix III,' paragraph III-4430 and Figure IWC-2500-7 of ASME Section XI, 1980 Edition, Winter 1981 Addenda.
Basis for Reliefr Complete ultrasonic examination of the weld length is obstructed by a small pipe support clamp adjacent to the end of the weld.
Obstruction by the support results in 50% of the weld volume not receiving two beam path coverage for the parallel scan (reference Figure 2).
Removal of this support would require weld removal with subsequent repair.
The subject weld and pipe support are located on the Residual Heat Removal System which contains a radioactive fluid. Therefore, removing this support would result in dose exposure to personnel and an extensive work effort without a compensating increase in safety.
Alternate Examination:
None.
The required volumetric examination was completed to the maximum extent possible without the undue burden of support removal.
ASME code Section III Components were accepted in accordance with the requirements of Section III, which included volumetric and surface examinations as well as pressure tests.
=
Attachm:nt to WM 95-0049 Page 6 of 9 Evaluation of Plant fla f ety r Strict! ASME Section III quality controls were used when designing, fabricating and installing the weld.
In addition, the weld was volumetrically examined (Preservice Inspection as well as the current Inservice Inspection) with no irregularities found.
The probability of a flaw occurring and not being detected by the performance of the volumetric examination is small.
Future indications of significant size would be discovered by the volumetric examination of the weld.
Based on the above, reasonable assurance of the continued inservice structural integrity of the subject weld will be achieved without providing a complete examination.
- l:
2.5 inches of de long seam l
p
.i
\\
\\
A 8
D
.4 inches from exit point to edge of pipe clamp on parallel scan in downstream direction.
po EJ02-S035-D N
e Down Stream m
Up Stream Q
e--
mQ}))) = E102-S035-D-LU m -s e--- m m .25 inches from center line of transducer to edge of pipe clamp on perpendicular scan from both sides of weld. (Drawings Not to Scale) FIGURE 2
Attachment to WM 95-0049 Prg? 7 of 9 ISI RELIEF REQUEST I1R-43 Comoonent: BB-01-S101-7, BB-01-S302-3, BB-01-S402-3 CaLecorv: ASME Section XI, 1980 Edition, Winter 1981 Addenda, Table IWB-2500-1, Examination Category B-J, Item Number B9.31. Descriptigni Reactor Coolant System Loop 1 Cold Leg, 10" Nozzle to 27.5" ID Pipe; Reactor Coolant System Loop 3 Hot Leg, 6" Nozzle to 29" ID Pipe; Reactor Coolant System Loop 4 Hot Leg, 14" Nozzle to 29" ID Pipe. Code Requirement: Requires the inner 1/3 of tL3 weld thickness plus 1/4 inch of the base metal beyond the weld toe to be scanned with a sufficiently long examination beam path to provide coveraga in two directions for reflectors parallel to the weld seam as specified by Appendix III, paragraph III-4420 and Figure IWB-2500-9 of ASME Section. XI, 1980 Edition, Winter 1981 Addenda. Basis for Reliefa volumetric examination of these welds was limited to being examined from the pipe side only because of the component geometry (pipe branch nozzle configuration) and metallurgic properties (centrifugally cast stainless steel). Because of the coarse grain material and high attenuative nature of the materials, it is necessary to use a refracted longitudinal sound wave to achieve the best ultrasonic response. This type of wave cannot be extended to provide two beam path direction coverage. Alternate Examination: l None. The required volumetric examination was completed to the maximum extent practical due to geometry and material attenuation variables. ASME Code Section III: Components were accepted in accordance with the requirements of Section III, which included volumetric and surface examinations as well as pressure tests. Evaluation of Plant Safety: ( I Strict ASME Section III quality controls were used when designing, fabricating, and installing this weld. This weld was ultrasonically inspected to the fullest extent possible, including examination of 100% of the volume in two beam path directions for reflectors transverse to the weld seata, with no irregularities identified. This fact, in conhb;' tion with the surface examination results and Reactor Coolant System visual examinotions (VT-2) following each refueling outage, provides confidence that the weld is structurally sound and that the limited exam does not compromise the health and safety of the public.
m 'Atta.chment to WM 95-0049 ~ ~ Pig;a 8 of 9 ISI RELIEF REQUEST IlR-44 enannnants j BG-01-FW322, BG-01-FW321, -BG-01-F026, BG-01-FW313 categorve i Augmented examination for break exclusion piping (NUREG-0800), performed to ASME Section XI, 1980 Edition, Winter 1C81 Addenda, Table IWC-2500-1, Examination Category C-F, Item Number C5.11 [ i Description Chemical and Volume Control System Charging Line 3" pipe to 3" pipe welds (BG-01--FW313 is at a flued head containment penetration) code Reonirementt Requires the inner 1/3 of the weld thickness plus 1/4" of the base metal beyond the weld toe to be scanned with a sufficient., long examination beam path to provide i coverage in two directions as specified by Appendix III paragraph III-4420 and Figure IWB-2500-7 of ASME Section XI, 1980 Edition, Winter 1981 Addenda. Basis for Relief,1 Complete ultrasonic examination of the weld was not feasible because of limitations in geometry and metallurgic ' properties. Geometric limitations resulted fromLweld shrinkage at the toe of the weld which causes loss of search. unit contact due to lift off. To perform a _ complete volumetric examination would require design modifications of the geometry to allow access for the ultrasonic examination. i Approximately 36.6% of the weld required volume was not examined in two l perpendicular direc*(ons with approximately 7.6% of that volume not examined in either perpendiculas frection (reference Figure 3). i Alternate Examination 1 None. The required volumetric examination was completed to the maximum extent practical due to geometry and material attenuation variables. } ASME code Section IIIr Components were accepted in accordance with the requirements of Section III, which included volumetric and surface examinations as well as pressure tests. l
Attschment to WM 95-0049 P ge 9'of 9 Evaluation of Plant Safety: Strict ASME Section III quality controls were used when designing, fabricating, and installing this weld. In addition, the weld has been volumetrically examined (Preservice Inspection as well as the current Inservice Inspection) with no irregularities found. A significant portion of the welds were examined - including a complete exam parallel to the weld; therefore, probability of not cetecting patterns of degradation is small. Based on the above, reasonable assurance of the continued inservice structural integrity of the welds is achieved without providing a complete examination. 45' 45' 45' toe TOE 60' t Oa l l \\ / sw -- Weld required volume not Examined = 7.6 percent +l -l -- Weld required volume not Examined in two directions = 36.3 percent (Drawing Not to Scale) FIGURE 3 ,}}