ML19347E955
| ML19347E955 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 05/08/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19347E953 | List: |
| References | |
| NUDOCS 8105140408 | |
| Download: ML19347E955 (21) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMEN 0 MENT NO. 61 TO FACILITY OPERATING LICENSE NO. NPF-1 PORTLAND GENERAL ELECTRIC COMPANY THE CITY OF EUGENE, OREGON PACIFIC POWER AND 8,IGHT COMPANY TROJAN NUCLEAR PLANT DOCKET NO. 50-344 The NRC staff has reviewed and evaluated the Inservice Inspection Program and associated Technical Specification changes (excluding pump and valve testing) for the Trojan Nuclear Plant and finds it in compliance with paragraph (g) of 10 CFR Part 50.55a, " Inservice Inspection Requirements."
The inservice inspection program was submitted by the licensee in letters dated December 28, 1979 and February 5, 1981. Related Technical Specification changes were croposed in letters dated March 22, 1977 as amended March 20, 1979.
In addition, a meeting was conducted with the licensee at the plant site on July 29-31, 1950 to review the program. Pursuant to 10 CFR Part 50.55a(g)
(6)(i), we have granted relief from specific requirements stated in the ASME Boiler and Pressure Vessel Code,Section XI,1974 Edition including Addenda through Summer 1975, which we have concluded to be impractical for this facility because of component or system design, geometry, or materials of construction.
In some cases, relief was granted only after imposing the alternate inspection or testing requirements which the staff deems necessary that such relief will not endanger life or property or the common defense and security and is otherwise in the public interest giving due censideration to the burden upon the licensee that would result-if the requirements were imposed on the facility.
In some cases, relief was not granted because of the factors stated in the evaluation of the specific request.
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Relief Reouest Evaluations 1.
Reactor Vessel Disc-to-oeel Seement Circumferential Weic Code Reouirement:
The volumetrfc examinations performed during each inspection interval shall cover at least 10% of the length of each longitudinal weld and 5% of the length of each circumferential shell weld and head weld.
Code Deviation Request:
Request reifef from volumetric inspection of reactor vessel closure head disc-to peel segment circumferential weld (Item 31.2, Category B-8).
.i Reason for Recuest:
The reactor vessel, T-201, is a Quality Group 1
[
component whicn is part of the pressure retatning boundary for the Reactor Coolant System.
The closure head for the reacter vessel is a hemispherical unit constructed of a frange, seven peel segments, and a disc.
The seven peel segments are joined to the disc by a full penetration circumferential weld. ~
Table IWB-2500 Item Number 81.2 (circumferential welds in the closure head) lists the examination method as voir. metric.
Table IWB-2500 Examination Category B-B (pressure retaining welds in vessels) requires examination of 5% of the length of each circumferential weld during each inspection interval.
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A This weld is completely enc.losed within the pattern of control
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rod drive mechanisms inside the shroud structure on the closure hea'd, is nct accessible for ultrasonic examination, and cannot be volumetrically examined.
The weld will be visually examined for
_evidcnce of leskage during system leakage and hydrostatic testing.
Leakage tests are required to be performed at system operating pressure prior to startup following each refueling shutdown.
Hydrcstatic pressure tests are to be performed at or near the end of each 10 year inspection interval.
Staff Evaluation:
The design of.the closure head and control rod crive penetration locations prevents volumetric examination of tne closure head peel segment-to-disc circumferential weld.
As an alternative and continuing inspection of the weld, the licensee has proposed to vtrify the integrity of these welds curing periodic -
pressure tests. This alternate examination will be a visual inspection of these welds during each Code required (IWB-5200) system leakage test prior to sti.rtup following each reactor refueling cutage.
The test will be performed at not less than the system nominal operating pressure at 100% rated reactor power.
Other welds on the closure head are examined to Code recuirements and are subject to additional examinations if unacceptable indica-tions are revealed. The visual inspection of the closure head peel segment-to-disc circumferential weld during the system leakage test at each refueling outage and accepta01e results from volumetric examination of other. closure head welds will provide assurance of the continued structural integrity of the closure head and will maintain an adequate level of safety.
Relief is therefore granted from the ASME Section XI requirements, subject to the conditions stated in this evaluation.
2.
Seal Monitorino Tube Penetration Code Reouirement: The area surrounding each penetration shall be examined for evidence of leakage during the pressure test.
Code Deviation Reauest:
Request relief from the visual examination of inner and outer seal monitoring tube penetrations (Item Bl.5, Category B-E).
Reason for Recuest:
The reactor vessel, T-201, is a Quality Group 1 component wnicn is part of the pressure retaining bouncary for the heactor Coolant System.
The closure head is sealed to the vessel by two 0-ring seals.
The vessel flange has two penetrations for closure head seal leakage monitoring.
The inner monitoring tube detects leakage across the inner 0-ring seal and the outer moni-torirg tuce detects leakage across the outer 0-ring seal.
Each of these tubes is connected by a partial penetration wela on the vessel flange gasket seal surface which is weld overlaid with 5/32 inch thick stainless steel.
These welds are outside the pressure 1
boundary for normal operation and will only be pressurized if the closure seals leak.
The conitoring tuces are 1 inen nominal pipe si:e.
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Table'IWB-2600 Item 81.5 (vessel penetrations) requires visual examination of these welds during hydrostatic testing.
Para-graph IWB-1220 exempts these components based on the size of the tubing, but again imposes a requirement for visual examination during hydrostatic pressure testing.
Volumetric (ultrasonic), surface, or visual examination of the welds cannot be performed due to the geometric configuration and inaccessiHlity due to the weld overlay.
Hydrostatic pressure testing of the welds is not feasible due to their location outside of the p essure retaining 0-ring seal on the vessel flange. These welds wii_1 only be pressurized in the event of loss of integrity of the seals.
Failure of both the 0-ring seal and the tuce welds is considered unlikely.
Loss ::f coolant due to complete severance of a monitoring tube can be made up by normal charging methods.
l Staff Evaluation: The reactor vessel at Trojan Nuclear Power Plant l
has a system designed to monitor reactor vessel head-seal integrity and leakage. The weids in question are 1 inch nominal pipe sizh and l
i are located outside the pressure boundary.
The inner 0-ring seal of l
the head-seal would have to fail in order to pressuri::e the component.
Due to geometric configuration, volumetric or surface examination is l
not practical. Hydrostatic examination is not practical bacause of the design of the component.
l Simultaneous failure of the closure head 0 ring seals and the l
tube welds is highly unlikely.
In addition, the makeup system can l
supply sufficient coolant to compensate for the failure of a monito-ing tube.
The design of the closure head seals and the L~
monitoring tube penetration provides an acceptable level of safety l
and assurance of structural integrity and therefore relief is i
granted from the ASME Section XI examination requirements.
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3.
Circumferential Sutt Weld l
Code Reouirement: The volumetric examinations performed during each j
inspection intervai shall cover all of the area of 25% of the circum-ferential joints including the adjoining 1 foot sections of longitudinal joints and 25% of the pipe branch connection joints.
Code Deviation Recuest:
Request relief from volumetric examination of Examination Category B-J Socolet to 3" pipe cap weld (3" SI-2501R-3-4)
Reason fc.,r Recuest:
This Quality Group 1 pressure retaining weld is at tne case of a 1" socolet connected to a 3" pipe cap.
The joint is a drain point for a 3" boron injection header (3" SI-2501R-3-4).
l Table IWB-2600 Item S4.5 (circumferential pipe welds) requires volumetric examination of this weld.
Table IWB-2500 Examination Category B-J (pressure retaining welds in piping) requires that 100%
of each selected weld be examined.
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Ultrasonic examination of this weld cannot be performed. The geometric configuration on the internal surface is not cenducive to standard ultrasonic examination techniques.
Examination of this weld will be by visual examination during hydrostatic testing in accordance with the requirements of IWB-5000.
The frequency of examination will be in accordance with the schecule requirements of Examination Category B-J of Table IW3-2500 and the hydrostatic test requirements of IWS-5000.
In addition, an alternative component will be randomly selected for examination as one cf the 25% of welds to be examined under Category S-J.
Staff Evaluation: We have evaluated the degree of inspectability of tne sucject welc and have determined tnat examination to the extent required by the code is not practical.
The design and geometric configuration of the Socolet to 3" pipe cap does not permit volu-metric examir.ation.
The surface examination and visual examination which the licensee has committted to perform will provide assurance that the structural integrity of the weld will be maintained.
Relief is therefore granted frcm the volumetric examination i
requirement, subject to the conditions stated in this evaluation.
4.
Class 1 and 2 Pinino Welds Code Recuirement: Volumetric examination of selected Class 1 e.nd 2 welcs curing the inspection interval.
Code Deviation Recuest:
Perform limited volumetric examinations.
Reason for Recuest:
Quality Groups 1 and 2 piping systems with l
geometric aiscontinuities or limited access welds are covered in l
Table IWB-2500 Examination Category S-J and Table IWC-2520 Examin-ation Category C-F and C-G.
The piping systems function as Quality Group 1 or 2 pressure retaining boundaries at various locations at Trojan.
Table IWB-2500 requires that the Quality Group 1 piping be examined volumetrically to the extent specified in Table IWS-2500.
Also, Table IWC-2500 requires volumetric examinations for Quality Group 2 piping to the extent specified in Table IWC-2520.
Exception is taken to the requirement to perform complete ultrasonic examination on the general types of configurations and limited access piping welds described below.
The basis for this relief request is practical in nature in that the ultrasonic examinations ca.not be fully performed to the extent required on the j
following general types of configurations:
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(1) For pipe-to-fitting or pipe-to-vessel noz:le welds, ultrasonic examination can be perfermed from the weld surface and pipe surface and, depending upon the geometric configuration, limited examination from the fitting side; l
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(a) for elbows or tees, ultrasonic examination can be performed from the fitting side except where the inside corner radius prevents ultrasonic coupling; (b) for valves and flanges, ultrasonic examination cannot be performed from the fitting side; (2) for fitting-to-fitting welds, ultrasonic examination may be possible from the weld surface but is restricted on both sides of the weld; and (3) for certain welds, hangers or seismic restraints may be so close to a given weld as to preclude or ifmit the ultrasonic l
examination.
When the general types of geometric configurations described above limit the accessibility of welds and their heat affected zones l
for examination by ultrasonic techniques, surface examinations will be performed to supplement the limited volumetric examination performed.
Supplemental surface examinations shall be performed at the frequency required for the original volumetric examinations in ASME,Section XI.
As the specific limitations become known for a given weid, they will be identified in the second 40 month program by revision.
l Staff Evaluation: These relief reques'ts will be reviewed and evaluated as tney are incorporated intp the program. The licensee must furnish with each relief request a technical justification demonstrating that an examination is finpractical to perform.
In addition, the specific weld identification and the extent of code required examination possible must be supplied.
5.
Integrally Weldec Succorts Code Reouirement:
The volumetric examinations performed during eacn inspection interval shall cover 25% of the integrally welded l
supports.
l Code Deviation Request:
Request relief from the volumetric examination of integrally-welded supports (Category B-K-1).
Reaso, for Recuest: The following piping assemolies have integrally weloeo supports wnich are attached by fillet welds:
Loop 1 Accumulator Discharge (1) 10" SI-2501R-2-1 Loop 2 Accumulator Discharge (1) 10" SI-2501R-2-2 1
l Loop 2 SIS & RHR Return (~2)
S" SI-2501R-19-1 i
5" SI-2501R-31-a Loop 3 Accumulator Discharge (1) 10" SI-2501R-2-3 Loop 3 SIS & RHR Return (2) 6" SI-2501R-31-5 l
Loop 4 Accumulator Discharge (1) 10" SI-25013-2-4 Loop 4 SIS & RHR Return (1) 8" SI-2501R-19-2 Loop a SIS & RHR Return (1) 5" SI-2501R-31-6 Loops 2 & 3 Pressurizer Spray (2) 4" RC-2501R-4-2 5
Loop 1 Boron Injection (1),
1-1/2" SI-2501R-3-60 Loop 2 Boron Injection (1) 1-1/2" SI-2501R-3-61 Loop 3 Boron Injection (2) 1-1/2" SI-2501R-3-64 Loop 4 Baron Injection (2) 1-1/2" SI-2501R-3-63 Loop 4 Auxiliary Spray (1) 2" CS-2501R-4-60 Table IWB-2500 Item No. 84e9 (integrally welded supports for piping pressure boundaries) requires volumetric examination of the support welds. Table IWB-2500 Examination Category B-K-1 (support members for piping, pumps, and valves) establishes the areas subject to examination as "... the welds to the pressure retaining boundary and the base metal beneath the weld zone and along the.upport attachment memcer for a distance of two support thickne ses."
The base material beneath a fillet weld cannot be examined by ultrasonic techniques due to geometric configuration.
The base.
material cf the pressure retaining pipe wall and the support attachment will be examined by ultrasonic techniques.
Surface examination will be performed on the fillet weld to supplement the limited volumetric examination.
The postulated failure for a fillet weld attachment is tnat cracking would initiate at the toe of the weld and as such would be detected by surface examination.
The examinations will be performed to the extent and frequency required by Table IWB-2500.
Staff Evaluation:
Because of the attachment weld design, ultrasonic l
testing or raciography are impractical' techniques to use and, if applied, would result in little added assurance of safety.
The licensee has committed to subject these welds to surface examination and to volumetrically examine the base metal.
Based on environmental and loading conditions of these types of welds, flaws would most likely generate at the weld surface and thus be detectable by surface examination.
Ultrasonic examination of the bare metal would provide assurance that flaws do not exist in the heat affected zone.
I We conclude that the limited volumetric examination supplemented by surface examinations on areas not covered by UT will provide an acceptable level of safety and assurance of structural integrity.
Relief is therefore granted from the ASME Code requirements, subject to the conditions stated in this evaluation.
5.
Reactor Coolant Pumo Baltinc Code Recuirement:
The volumetric examinations performed curing each inspection interval shall cover 100% of the bolts, studs, nuts, bushings, and threads in base material anc flange ligaments between threaded stud holes:
Bolting may be examined either in place under tension, when the j
co.nnection is disassemoled, or when tne bolting is removec.
Code Deviation Recuest:
Recuest relief from tne volumetric examination of reactor coolant como bolting (Category S-G-1).
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Reason for Reouest: The reactor coolant pumps (RCP), P-201A, P-2018, P-201C and P-2010, are Quality Group 1 components which are part of the pressure retaining boundary for the Reactor Coolant System.
Each RCP has twelve (12) 2-inch diameter bolts which connect the seal housing to the pump.
Table IWB-2600 Item Number 85.1 (pressure retaining bolts and studs in place) requires a volumetric examination of the studs.
The bolts are of the socket head type and volumetric examination by standarJ ultrasonic examination techniques cannot be performed with the belts in place.
Volumetric examination of the bolting will be performed in accordance with Table IWS-2600 Item 35.2 (pressure retaining bolts, when removed) when the seal housing is disassembled for other reasons. As a minimum, one of the four reactor coolant pumps !s to be disassembled each ten year inspection interval.
Staff Evaluation: The design of the seal housing bolts prevent's ultrasonic examination ard radiography is an impractical technique to use with the bolting in place.
To disassemble a reactor coolant pump at the frequency required solely to perform the examination of bolting is impractical and places an undue burden on the licensee without provfuing a comparable increase in the level of safety of the facility.
Sys, tem leakage monitoring is presently performed and will provide some assurance of the condition of the seal housing bolts.
In addition, the bolting will be examined whenever the reactor coolant pumps are disassembled, which is a minimum of once every ten year inspection interval for one of the four pumps. We conclude that the alternate examinations the licensee will conduct provide an adequate level of safety and assurance that the integrity of the bolting will be maintained.
Relief is therefore granted from the ASME code requirements, subject to the conditions stated in tnis evaluation.
7.
Regenerative Heat Exchangers Code Reouirement: The volumetric examinations shall cover at least 20% of eacn circumferential weld, uniformly distributed among three areas around the vessel circumference.
Code Deviation Recuest:
Request relief from the volumetric examination of circumferential welds in the regenerative heat exchanger (Category C-A).
Reason for Recuest: The regenerative heat exchanger (RHX) is identifiea in the F5AR as E-206 and is classified as Quality Group 2.
The RHX is a pres,sure retaining boundary in the Chemical and Volume Control System. -It is used for heat transfer to reduce reactor coolant temperature prior to purification and to preheat the reactor coolant prior to its return to the reactor coolant loops.
Table IWC-2600 Item No. C1.1 (circumferential butt welds) requires volumetric examination of the circumferential welcs.
Tacle IWC-2520 Examination Category C-A (pressure retaining welcs in pressure 7
vessels) requires examination of,"... the weld metal and base metal for one plate thickness beyond the edge of the weld joint" on 20% of each circumferential weld.
Exception to full volumetric examination of the welds on the RHX is taken as only a straight beam scan can be performed.
The RHX is a cast component.
Therefore, the calibration block for this component is also cast to the same specification and of the same material as the RHX.
During ISI for refueling core outage (I-II) terformed from March 17, 1978 through May 24, 1978, it was reported that the calibratior, block caused metallurgical noise signals that prevented angle beam calibration.
The limited volumetric exaraination (straight beam only) was, therefore, supplemented by the addition of surface examination.
The welds in the cast RHX shall be ultrasonically examined by the straight-beam methed and supplemented by surface examinations.
The examination frequency shall be as required by ASME Section XI for the volumetric examinations on this component, Staff Evaluation:
The ultrasonic examination of cast stainless steel material does not always produce reliable and meaningful results. The material properties of cast stainless steel attenuate and scatter ultrasound to the degree that some examinations tre effectively impossible. The licensee has proposed to pe-!vrm ultra-t sonic examinations using the straight beam method, but cannot effectively perform the angle beam examinations requ. red by the ASME Code.
'he substitution of a surface examination for the angle beam examination, and the limited volumetric examination will provide adequate assurance that the structural integrity of the heat exchangers will be maintained.
Relief is therefore granted frcm the angle beam examinations required by the Code, subject to the conditions stated in this evaluatica.
8.
Reactor Coolant Filter, Seal Watar Heat Exchancer and Seal Water leEurn Filter Code Requirement: The volumetric examinations shall cover at least 20% of each circumferential weld, uniformly distributed among three areas'around the vessel circumference.
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Code Deviation Recuest:
Request relief from the volumetric examination of:
Reactor Coolant Filter, Seal Water Heat Exchanger, Seal Water Return Filter (Category C-A).
l Reason for Reouest: The reactor coolant filter is identified in the FSAR as F-204, tne seal water return filter as F-209, and the seal water heat exchanger as E-203.
All are classified as Quality Group 2.
The seal water heat exchanger and the seal water return fi. iter are part of the pressure retaining Class 2 boundary between the reactor coolant pumps and the charging pump suction, while the reactor coolant filter is part of the pressure retaining Class 2 boundary between the deminerali:ers and the volume control tank.
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Table IWC-2600 Item No. C1.1 (circumferential butt welds) requires volumetric examination of the vessel welds. Yable IWC-2520 Examination Category C-A (pressure retaining welds in vessels) requires examination of 20% of each weld.
The thickness (0.165 to 0.185 inch) of the material used to construct the thin-walled pressure vessels described above is such that the combined " dead zone" and "near-fielc" effect of the ultrasonic transducer would render ultrasonic' examination meaning-less. Volur;tric examination of these welds will not be performed.
Surface and visual examinatice.s of weids on these vessels shall be performed as an alternative method at the frequency and extent required in Tables IWC-2520 and IWC-2600 for volumetric examinations.
Staff Evaluation: Due to the thin wall material, obtaining meaqingful ult asonic test res;1ts is not possible.
The 1977 Edition of the ASME Code recognizes the difficulty of conducting useful volumetric examinations of thin wall pipe (less than.5 inch wall), and therefore requires only a surface examination for su'ch pipe.
The surface and visual examinations which the licensee will perform are adequate to detect safety significant flaws and will therefore provide assurance that the structural integrity of these components will be maintained.
Relief is therefore granted for ASME Section XI requirements.
9.
Residual Heat Exchanger Nozzle-to-Vessel Weld Code Recuirement: The volumetric examination shall cover 100% of tne nozzle-to vessel attachment weld.
0 1
Code Deviation Recuest:
Request relief from the volumetric examination of the desidual Heat Exchanger nozzle-to-vessel welds (Categocy C-B).
Reason for Recuest: The RHRS heat exchangers, E-212A and E-2128, are of tne tuce and shell type with the tube side classified as Quality Group 2.
The RHRS system transfers heat from the Reactor Coolant System to the Component Cooling Water System to reduce and maintain the temperature of the reactor coolant to cold shutdown temperature.
The nozzle-to-vessel welds on the tube side of the heat exchangers are listed under Table IWC-2600 Item No. C1.2 (nozzle to vessel welds) with a requirement for volumetric examination.
Table IWC-2520 Examination Category C-8 (pressure retaining nozzle welds in vessels) requires examination of 100% of the nozzle-to-vessel attachment.
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Access for the ultrasonic examination of each RHRS heat exchanger nozzle-to vessel is locally restricted by the adjacent vessel supports and tuce sheet flange and examination cannot be performed on 100% cf the -eld.
Access for ultrasonic examination is estimated at 75% of the total. eld.
Surface examination will be performed on 100% of the weld to supplement the limited ultrasonic 9
examination.
The welds will be examined at the frequency required by. Paragraph IWC-2411 for multiple loop systems.
Staff Evaluation:
The geometric configuration of the nozzle crevents ultrasonic examination coverage to the extent required by Code.
The licensee estimates that 75% of the weld can be examined by ultrascnic methods and the remainder by surface examination.
These examinations and the visual examinations of the welds during periodic hydrostatic testing will provide assurance that an adequate level of safety will be maintained.
Relief is therefore granted from the ASME Section XI requirements, subject to the conditions in tnis evaluation.
10.
RHR Pumo Circumferential Butt Welds Code Reouirement: The volumetric examination sh'all include 100% of tne selectea welds.
Code Deviation Recuest:
Request relief from the volumetric examination of tne residual heat removal pump suction circumferential butt welds (Category C-F).
Reason for Recuest:
These Quality Group 2 pressure retaining weids are on tn2 spool piece on the suction of each RHRS pump, P-202A and P-2028 (14". RH-601R-5-2).
Table IWC-2500-Item C2.1 (circumferential butt welds) requires volumetric examination of the welcs. Table IWC-2520 Examination Category C-F (pressure retaining welds in piping which circulates reactor coolant) requires examination of 100% of each weld.
Accessibility of these welds is such that ultrasonic examination cannot be performed.
In each case, there is a flange on one side of the weld and a support on the other side.
The weld will be ultra-sonically examined to the maximum extent possible if either support is removed for maintenance and will be visually examined during hydroctatic testing required by IWC-5000.
Staff Evaluation-The licensee has indicated that these two welds were omitted from the preservice inspection program and hence do not require examination during inservice inspections unless IWC-2430 becomes effective.
A relief request should be submitted at that time for evaluation by the staff.
11.
Charging Pumo Casing Welds Code Recuirement:
The volumetric examination shall include 100% of tne selectea welds.
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Code Deviation Recuest:
Request relief from the volumetric examination of tne cnarging pumo casing welcs (Category C-F).
Reason for Recuest The centrifugal charging pumos, P-205A and P-2053,'provice raxeup of reactor coolant curing normal reactor 10
operation.
These pumps are part of the Quality Group 2 pressure retaining boundary for the Chemical and Volume Control Sys*.em.
Table IWC-2600 Item C3.1 (pump casing welds) requires volumetric examination of the welds.
Table IWC-2520 Examination Category C-F (pressure retaining welds in pumps which circulate reactor coolant) requires examination of 100% of each weld.
The pressure retaining welds in the charging pump casings are not accessible for examination.
Volumetric or surface examination requires complete disassembly of the pump casing and removal of the inboard seal housing and rotor assemoly.
Ultrasonic examination will be conducted whenever a pump is disassembled for maintenance reasons or near tne eno af each 10 year interval.
S_taff Evaluation: 1M disassembly of the charging pumps, requiring anproximately 1000 manhours of labor, and the associated e>tposure to personnel resulting from inspection of the casing welds at the frequency required by Code (i.e., approximately 1/3 of the casi'ng welds each inspection period), makes this requirement impractical.
The licensee has committed to examination of 100% of the casing welds when the pump is disassembled for maintenance reasons or near the end of the 10 year interval.
This alternate inspection frequency which the licensee will adopt is sufficient for assuring that the structural integrity of the pump casing will be maintained throughout the inspection l
interval.
Relief is therefore granted from the ASME code requirements, subject to the conditions stated above.
i 12.
Calibration Blocks for Ferritic Vessels Code Recuirement:
Paragrach I-3121 of ASME Section XI, Appendix I, requires that the ultrasonic calibration blocks for ferritic vessels 2.5" and over in wall thickness be fabricated "... from one of the following:
(1) the component no::le dropout; (2) the l
component prolongation; or (3) when it is not possible to fabricate the block from material taken from the component,'it may be l
fabricated from a material of a specification included in the applicable examination volumes of the component.
The acoustic velocity and attenuation of such a block shall be demonstrated to fall within the range of straigat beam longitudinal wave velocity and attenuation found in the unciad components".
Code Deviation Request:
Exception is taken to the block naterial to be usec, as cefinec aoove, for ferritic vessels with walls 2.5" thick and over at Trojan.
Instead, the blocks will be fabricated in accordance with the requirements of ASME Section V, paragra;;h T434.1.1.
Reason for Recuest:
None of the alternatives described above can be met cecause (1) tne components are already clad and therefore, it is impossible to obtain a comparison of straignt beam velocities anc attenuation in the unciad component and (2) ccmconent no::la 11
dropouts and component prolongations are not available for the fabrication of calibration blocks.
However, material meeting the originai constrc.ction specifications, as described above, is available and shall be used for the calibration blocks.
No additional examinations of ferritic vessels with walls 2.5" thick and over are necessary because the requirement to perform the ultrasonic examination is not being excepted, only the source of material for fabricating the calibration blocks.
The calibration blocks used fer Trojan, since they are made from the same specifi-cation as the vessel, are equally as valid as those described in Appendix I.
Staff Evaluation The alternative provisions proposed by the licensee are found in Article T434.1.1 of Article 4 of Section V, Winter 1976 #ddenda.
The licensee.has requested relief from specific provisions of Appendix I " Ultrasonic Examination" concerning the'materisi selection of the calibration blocks.
Appendix I was first published in the Summer 1973 Addenda and is limited in scope to Class 1 and 2 ferritic vessels 2-1/2 inches and ovec in wall thickness.
In the 1977 Edition of Section XI, Appendix I was
- uperseded by Article 4 of Section V.
Article T-434.1.1 of Section V, Winter 1976 Addenda, is the current. requirement for calibration block materials for these components in accordance with 10 CFR 50.55a(b).
Therefore, we conclude that Article T-434.1.1 of Section V is an acceptable alternative provision that may be substituted in lieu of Article I-3121 of Section XI.
Relief from cladding of the calibration blocks was not requested and therefore, the cladding requirement in the code must be met.
13.
Use of Aopendix III for Pioino System Examinations Code Recuirement:
Paragraph IWA-2232 requires that when ultrasonic examination is used, the examinations are to be performed in accordance with Appendix I (Section XI) or Article 5 of Section V as applicable.
Article 5 of Section V specifies procedures for piping weld examination.
Code Deviation Recuest:
ASME Section XI, 1974 Edition through the Summer 1975 Accenda is applicable for the general ISI requirements at Trojan.
However, exception is taken to use of Article 5 of Section V for the ultrasonic examination of piping.
- Instead, Appendix III of Section XI, 1974 Edition, Winter 1975 Addenca shall be used.
Reason for Recuest:
It is recognized that Appendix III, Winter 1975 Accenoa nas not been officially endorsed by the NRC by reference in 10 CFR 50.
However, Appendix III contains the first guidelines published by ASME for the ultrasonic examination of piping welds and its use is essential to obtain meaningful test data.
No additional examinations of welds in Quality Group 1 or 2 piping systems shall be required because one set of UT examination tech-niques is being substituted with a more meaningful set and the 12
actual requirements to perform the UT examin'ations are not being excepted.
Staff Evaluation: Appendix III was subsequently incorporated the 1977 Edition tnrough Summer 1978 Addenda of Section XI, which is approved in 10 CFR 50.55a(b).
Under the provisions of 50.55a(g)
(4)(iv), the licensee may update to the requirements in later code editions and addenda, subject to NEC spproval.
Hence, relief is not required if the requirements in the 1977 Edition through Summer 1978 are utilized. However, to maintain the ultrasonic recording sensitivity, the staff requires the following procedure for DAC recording levels:
A.
Indications 50% of DAC or greater shall be recorded.
B.
An indication 100% of DAC or greater shall be investigated by a Level II or Level III examiner to the extent necessary to determine the shape, identity, and location of the reflector.
C.
Indications 20% of DAC or greater whien are interpreted to be a crack must be identified and evaluated to the rules of Section XI.
D.
The owner shall evaluate the results of esch examination and test as noted in IWA-1400(i).
J 14.
Cla=s 2 Hydrostatic Examinations Code Recuirement:
The system hydrostatic test pressure shall be at least 1.25 times the system design pressure and conducted at a temperature not less than 100*F except as may be required to meet the test temperature requirements of IWA-5230.
Code Deviation Recuest:
Request relief from the hydrostatic testing requirements of Class 2 piping that cannot be isolated from Class 1 piping.
Reason for Reouest:
A.
(1) Reactor coolant loop flow meter elbow taps for flow transmitters FT414, FT415, FT416, FT424, FT425, FT426, FT434, FT435, FT435, FT444, FT445 and FT446.
(2) Reactor coolant loop' resistance temperature cetector system (RTD) vent and drain lines (3/4" RC-2501R-17).
(3) RTD system return instrument lines for flow indicator switches FIS417, FIS427, FIS437 and FIS447.
(4) Reactor coolant loop sampling lines from loop 1 to manually-operatea gicbe valve 3056 and from loop 3 to manually-operated globe valve 5077 (3/4" RC-2501R-30).
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I (5) Reactor vessel inner and outer seal mnnitoring tube piping to manually-operated globe valves 8069A and 80698 (3/4" RC-2501R-15).
(6) Pressurizer spray control valve by pass lines (3/A" RC-2501R-4).
(/) Pressurizer in.itrument lines for level transmitters LT459.
LT460, LT461, LT462 and' pressure transmitters PT455, PT457, PT456, PT458, PT467A and PT4678.
(8) Pressurizer steam space sampling line fram the pressurizer power-operated relief valve piping to manually-operated globe valves 8078 and 8094 (3/4" RC-2501R-29).
.(9) Pressurizer liquid space sampling line from the pressurizer to manual.ly-operated globe valve 8080 (3/4" RC-2501R-29).
(10) Pressurizer safety valve seal water drain lines to manually-operated glove valve 8093 (3/4" RC-2501R-12).
Chemical and Volume Control System (CVCS}
(11) Reactor coolant pump (RCP) seal by pass lines from flow orifices F01957, F01958, F01959 and F01960 to air-operated glove valve CV-8142 (3/4" CS-2501R-28).
(12) RCP seal ieak off lines from'the RCP to air-operated globe valves CV-8141A, CV-8141B, CV-8141C and CV-8143" (2" CS-2501R-28).
(13) RCP seal injection and seal by pass vent and drain lines from the Quality Group 1 piping to manually-operated globe valves 8363A, 83638, 5363C, 83630, v364A, 83648, 8364C and 8364D.
Resioual Heat Removal System (RHRS)
(14) RHR instrument sensing lines for pressure transmitters PT403 and PT405.
Safety Injection System (SIS)
(15) Accmulator discharge test line connections (3/4" SI-2501R-22) from the Quality Group 1 piping to air-operated globe valves CV-8877A, CV-8879A, CV-88778, CV-88798, CV8877C, CV-8879C, CV-88770 and CV-88790.
(16) Boron injection tank, T-207, discharge to the RCS cold legs test line connections (1" SI-2501R-23 and 3/4" SI-2501R-1) from the Quality Group 1 piping to air-operated globe valve CV-8882.
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(17) SIS pumps, P-203A and P2035, disch'arge to the RCS loops hot legs' test line connections (3/4" SI-2501R-22) from the Quality Group 1 piping to air-operated globe valves CV-8889A, CV-88898, CV-8889C and CV-88890.
The pipelines are all Quality Group 2 penetrations into a l
Quality Group 1 pressure boundary without an isolation valve or other me ns-for isolating the Quality Group 2 system from the Quality Group 1 system for hydrostatic testing. The transition between Quality Groups is made by a 3/8" diameter orificed connection. This hole size restricts flow such that loss of coolant da to severence of one of these lines can be made up by normal cnarging methocs.
The components within each line are exempt from volumetric i
examination under the provisions of IWC-1220(d).
The pipe lines are equired to be visually examined during hydnostatic pressure testing by IWC-2412(a).
Pressurizing the pipe lines 4
to the hydrostatic test pressere required by IWC-5000 would r< quire pressurizing the Quality Group 1 system to a pressure in excess of that required by IWB-5000.
Pressurizing the
-Reactor Coolant System is undersirable because of the limita-tions on the hydrostatic test pressure and the number of hydrostatic test cycles incorporated into the design of the system components (most notably the reactor vessel and fuel assemblies).
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Visual examination for evidence of leakage will be conducted on the identified portions of these systems at the hydrostatic pressure required by Paragraph IWB-522] for the 2
adjoining Quality Group 1 systems, Hydrostatic pressure tests will be performed at or near i
the end of each 10 year inspection interval in accordance with Paragraph IWB-5210.
B.
Quality Group 2 piping systems which are connected to a Quality Group 1 boundary by a check valve oriented for flow into the Quality Group 1 system.
Chemical and Volume Control System (CVCS)
(1) - Normal charging line and by pass line (3" CS-2501R-5 and 3/4" CS-25: 1R-4) from air-operated globe valve CV-8116 and manually-operated globe valve 8393 to check valve 83788.
(2) Alternate charging line (3" CS-2501R-6) from air-operated globe valve CV-8147 to cneck valve 85798.
(3) Reactor coolant pump seal injection lines (2" CS-2501R-28) from manually-operated glooe valves 8352A, 83523, 8352C i
and 83520 to check valves 8350A, E3508, 83500 and 83500.
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Residual Heat Removal System (4) RHR return to the RCS cold legs (8" SI-2501R-31) from motor-operated gate valve MO-8809A to check valves M0-8818A and MO-8818B; and from motor-operated gate valve M0-88098 to check valves MO-8818C and MO-8818D.
(5) RHR discharge header to RCS loops 2 and 4 (3/4" and 19" RH-2501R-19) from motor-operated globe valve MO-8703 and manually-operated globe valve CV-8825 to check valves 8736A and 87368.
Not required as per IWC-5220(c).
Pipe lines listed under Items (1) and (2) are Quality Group 2 piping pressure boundaries which are part of the letdown return to the reactor coolant system and are normally pressurized to reactor coolant system pressure.
Pipe lines' listed under Item (3) are Quality Group 2 piping pressure boundaries on the discharge of the charging pumps and are normally pressurized to reactor coolant system operating pressure.
Pipe lines listed under Items (4) and (5) are Quality Group 2 to Quality Group 1 boundary change through a check valve.
The pipe lines are required to be visually examined during hydrostatic test by IWC-2510.
Pressurizing the pipe lines to the hydrostatic press'ure required by IWC-5000 would require pressurizing the Reactor Coolant System in excess of that required by IWB-5000 due to the flow direction of the check valve being from the Quality Group 2 system to the Quality Group 1 system.
Pressurizing the Reactor Coolant System is undesirable because of the limitations on the hydrostatic test pressure and the number of hydrostatic test cycles incorporated into the design of the system components (most notably the reactor vessel and fuel assemblies).
Visual examination for evidence of leakage will be conducted on the identified portions of these systems' at hydrostatic test pressures in accordance with the requirements of IWB-5221 for the adjoining Quality Group 1 systems.
IWB 5210 requires hydrostatic pressure tests at or near the end of each 10 year inspection interval.
Note:
Similar pipe lines exist in the Safety Injection System:
Baron injection tank, T-207, discharge piping to the RCS loops. cold legs (3" SI-2501R-3) and the test connection piping (3/4" and 1" SI-2501R-3) from motor-operated globe valves M0-8801A and MO-88018 and air-operated globe valves CV-8843 and CV-8925 to check valve 8815.
Safety injection pumos, P-203A and P-2033, discharge to the RCS loops hot legs (2" 2501R-1) from manually-16
operatedglobevalves8816A,88165,8816Cand88160to check valves 8905A, 89058, 8905C and 89050, respectively.
However, Paragraph IWC-5220(c) allows for testing these systems at normal operating pressure during inservice testing since they are not required to operate during reactor operation.
Hence, relief is not required for these lines.
Staff Evaluation: The design of the subject systems prevents isolation of Class 1 and 2 systems at the class boundary.
To prevent overpressurization of the Class 1 components requ'res that the portions of Class 2 systems be tested at the same time as the hydrostatic test for the reactor vessel.
The difference in test pressure between Class 1 and 2 is not large and leaks will be adequately detected in the Class 2 lines subjected to the Class 1 test pressures. We conclude that this alternative test procedure will be acceptable in providing assurance of the systems' integrity during the inspection interval and therefore grant relief from the ASME Section XI requirements.
15.
Class 3 Comoonents and Supports Code Recuirement:
IWD-2400 requires visual examination of 100% of the Quality Group 3 components and supports while the system is in operation or undergoing system testing each 40-month period and during hydrostatic testing for eacn 10 year interva'l.
Code Deviation Recuest:
Deleta visual examination when radiation exposure exceeds.1 man rem or physical constraints prohibit examination.
Reason for Recuest: Quality Group 3 standards are applied to Seismic Category I water, steam, and radioactive waste containing pressure vessels (other than turbines and condensers), storage tanks, piping, pumps, and valves not part of the reactor coolant pressure boundary nor included in Quality Group 2 but part of:
(1) Cooling water and auxiliary feedwater systems or portions of these systems that are required for (a) emergency cooling; (b) post-accident Containment heat removal; (c) post-accident Containment atmosphere cleanup; or (d) residual heat removal from the reactor and from the spent fuel storage pool.
Portions of the systems required for their safety functions that do not operate during any mode of normal reactor operation or cannot be tested adequately or classified as Quality Group 2.
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(2) Cooling water and seal' water systems or portions of these systems that are required for functioning of other systems or components important to safety such as residual heat removal pumps.
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(3) Systems or portions of syst, ems that are connected to the reactor c -olant system and are capable of being isolated from that system during all modes of normal reactor operation by two
. valves, each of which is either normally closed or capable of automatic closure.
(4) Radioactive waste treatment, handling and disposal systems, and other systems where failure of components would result in release to the environment of radioactive gases required to be held for decay.
Exception is taken to visual examination of Quality Group 3 components and supports when the following criteria apply:
Radiation Exposure - In order to limit personnel exposure a limit of 0.1 man-Rem / inspection area is imposed.
This limit will be used in determining which components, systems, portions of systems, or supports and hangers (for components exceeding 4-inch nominal pipe size) will be examined.
Using known or estimated radiation levels and estimated required examin'ition time, the extent of the system (if any) to be examined will be determined. Those components, systems or portions of systems, and !Jpports and hangers (for Components exceeding 4-in nominal pipe size) which were not examined will be recorded as exceptions due to radiation exposure.
Physical Constraints *- Those components, systems, portions of systems, or supports and hangers (for components exceeding 4-inch nominal pipe size) which are not examined for the following reasons will be denoted as exceptions due to physical constraints.
(1) Horizontal pipe runs which are greater than 10 ft above, below or beyond the viewing platform, walkway, hallway, ladder, etc being used by the examiner.
(2) Areas which cannot be adequately seen by the examin e due to interference from other systems, components, etc.
(3) Components, uninsulated welds, hangers or supports which cannot be viewed for a 360* examination from a distance of less than or equal to 2 feet.
NOTE:
Inspection mirrors will be used to gain the required 360* examination when possible.
In the event that accessibility is provided by reduction in the radiation levels or by other maintenance requirements the componer.ts will be exam bed to the extent possible.
Staff Evaluation: The licensee has not proviced sufficient justification for relief to be granted.
Additional details for i
particular examinations must be provided to demonstrate that j
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1 examinations are impractical based on desigri, geometry, or materials of construction, as required by 50.55a(g).
The licensee will identify specific limitations for a given component, system, or portion of systems as they become known and these will be evaluated as relief requests at that time.
16.
Nozzle Inner Radius on Steam Generators Code Requirement: Volumetric examination of 100% of the nozzle inner radius during each inspection interval.
Code Deviation Recuest:
Perform a visual examination of nozzle inner radius in lieu cf volumetric examination.
Reason for Recuest: These are four (4) steam generators of the vertical snell and U-tube evaporator type at the Trojan Nuclear Plant. The portions of each steam generator which contain. reactor coolant pressure are classified Quality Group 1, and the portions which contain the steam generating system are classified Quality Group 2.
The Quality Group 1 portion of each steam generator consists of the hemispherical. bottom head with inlet and outlet nozzles, a ver-tical partition plate for dividing the inlet and outlet chambers, a tube plate, and inverted U-tubes. Manways are provided in the bottom hemispherical head for access to both sides of the partitioned heaJ.
The bottom head is cast with the nozzles as an integral part; therefore, there are no nozzleato-head welds.
The reactor coolant inlet and outlet aozzles are tapered with an inner radius section.
The general radiation in the area is 155-30 Rad per hour, gamma plus beta.
The outer surface of the bottom head is in the as-cast condition which precludes performing an ultrasonic examination of the inner radius.
The inner surface of the bo.ttom head is clad which precludes performing a surface examination of the inner radius.
The nozzle inner radius will be visually examined from the manway opening using manual or remote techniques each time a steam generator ISI tube inspection is performed.
Staff Evaluation: The geometric constraints of a rough, as-cast outer surface and a clad inner surface prevent volumetric and sur-face examination from being performed.
However, the licensee has agreed to conduct visual exami'ations of the nozzle inner radius n
area during each steam generator inservice inspection, which is a frequency greater than that required by the code. We find this alternative examination sufficient for providing reasonable assurance of the structural integrizy of the nozzle inner radii and therefore grant relief from the code examination requirements.
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II. Additional Relief Reouests In addition to the relief requests evaluated in Section I, the licensee submitted one other request for relief which involved updating examination requirements to the 1977 Edition through Summer 1978 Addenda of Section XI of the ASME Code.
Updating to the requirements of later NRC approved Editions and Addenda is permitted by 50.55a(g)(4)(iv), provided all of the related requirements of the respective editions or addenda are met.
We have evaluated.the following relief request submitted by the licensee and find it to be in accordance with 50.55(g)(4)(iv):
Relief Recuest Examination Icentification Category Comoonent 4.2.2 8-I-1, Item B1.13 Closure Head Claddi,ng III. Summary Based on the evaluations of the requested relief from code requirements, we conclude that the Trojan Nuclear Plant Inservice Inspection Program meets the requirements of the 1974 Edition through Summer 1975 Addenda of the ASME Section XI Code to the extent practical and thus is in compliance with 10 CFR 50.55a(g).
Environmental Consideration
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We have determined that this action does not authorize a change in effluent types or total amounts nor an increase in power level end will not result in any significant environmental impact. Having made this determination, we have further concluded that this action involves a matter which is insignificant frcm the standpoint of environmental impact and, pursuant to 10 CFR 551.5(d)(4), that an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of this amendment.
Conc ~usion We have concluded, based on the considerations discussed above, that:
(1) because this action does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety margin, it does not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the oublic will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of this amendment will not be inimical to the comnon defense and security or to the health and safety of the public.
Date: May 8, 1981 20