ML052560093
| ML052560093 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 09/08/2005 |
| From: | Pace P Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML052560093 (13) | |
Text
Tennessee Valey Authority, Post Office Box 2000, Spring City, Tennessee 37381-2000 SEP 0 8 2005 10 CFR 50.55a U. S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
In the Matter of
)
Docket No. 50-390 Tennessee Valley authority
)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 -
AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME)
SECTION XI INSERVICE PRESSURE TESTING PROGRAM REQUEST FOR RELIEF ISPT-09 Pursuant to 10 CFR 50.55a(a)(3)(ii), TVA is requesting relief from ASME Code requirements.
The request for relief is associated with the test methods for pressure testing ASME Code Class 1 piping and components that are normally isolated from full reactor coolant system (RCS) pressure during pressure tests.
TVA has determined that a hardship exists for testing the isolated components and is proposing alternative methods of pressure testing these Class 1 segments of pipe by pressure testing at a reduced pressure and temperature.
The alternative methods are described in the Enclosure.
The WBN ISPT Program is currently in the first 10-year interval.
NRC's review and approval is requested to support pressure testing activities for the WBN Unit 1 Cycle 7 Refueling Outage scheduled in the Fall 2006.
The enclosed request is similar to TVA's Sequoyah Nuclear Plant (SQN) request for relief (ISPT-09, Revision 1) dated January 3, 2005, with the exception of addressing the WBN auxiliary spray line.
NRC's approval for the SQN relief request was dated April 8, 2005.
- canf
U.S. Nuclear Regulatory Commission Page 2 SEP 0 8 2005 There are no regulatory commitments associated with this submittal. If you have any questions concerning this matter, please call me at (423) 365-1824.
Sincerely, P. L. Pace Manager, Site Licensing and Industry Affairs Enclosure cc (Enclosure):
NRC Resident Inspector Watts Bar Nuclear Plant 1260 Nuclear Plant Road Spring City, Tennessee 37381 Mr. D. V. Pickett, Project Manager U.S. Nuclear Regulatory Commission MS 08G9a One White Flint North 11555 Rockville Pike Rockville, Maryland 20852-2738 U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
UNIT FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 1
Summary:
Implementation of certain ASME Section XI Code requirements for inservice pressure testing of certain ASME Class 1 piping segments under current plant design would violate the design and 10 CFR 50.55a(c) (2) (ii) requirements for dual isolation capability of the reactor coolant pressure boundary.
Compliance with the ASME Section XI Code test pressure requirements presents a hardship which is not commensurate with the increase in safety provided by compliance with the requirement.
The proposed alternative for pressure testing of these segments of the ASME Section XI Class 1 boundary provides an acceptable level of quality and safety.
TVA requests authorization to use these alternatives in accordance with 10CFR50.55a (a) (3) (ii).
The WBN first ten-year inservice inspection interval began on May 26, 1996 and will be completed December 26, 2006.
The end of the inspection interval was extended beyond ten calendar years to coincide with the WBN Unit 1 Cycle 7 refueling outage as permitted by paragraph IWA-2430(c) (1) of ASME Section XI.
Unit:
1 System:
- System 68 (FSAR Figure 5.1-01, Sheet 1)
Safety Injection System (SIS) - System 63 (FSAR Figure 6.3-01, Sheet 1)
Residual Heat Removal System (RHR)
System 74 (FSAR Figure 5.5-04, Sheet 1)
Component:
Class:
Function:
SIS and RHR system piping segments which are part of the reactor coolant pressure boundary located between the primary and secondary isolation valves from the reactor pressure vessel 1
The piping segments listed in Table 1 are connected directly to the RCS and provide reactor core cooling water injection flow paths during normal shutdown and startup conditions, and during postulated emergency conditions.
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ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 Code Requirement From Which Relief is Requested:
Basis for Relief:
ASME Section XI, 1989 Edition, Table IWB-2500-1, Examination Category B-P, Note 2 requires that the pressure retaining boundary during the system hydrostatic test shall include all Class 1 components within the system boundary.
Paragraph IWB-5222(a) requires that the test pressure be not less than 102 percent (%) to 110% of the nominal operating pressure associated with 100% rated reactor power and as specified in Table IWB-5222-1.
The piping segments listed in Table 1 are connected directly to the RCS and, in accordance with the reactor coolant pressure boundary definition in 10 CFR 50.2, are classified as ASME Class 1 up to and including the second isolation valve.
Each of these piping segments, except for the RHR system piping, is isolated from the primary RCS by a self-actuating check valve designed to prevent primary reactor coolant from escaping the RCS, while providing a passive injection flow path for coolant injection.
The use of check valves in these piping segments for isolation from the RCS prevents, by design, their pressurization by the primary RCS, and conversely, their pressurization to any pressure greater than that in the RCS.
The RHR piping segment is also connected directly to the RCS, however, this piping is isolated from the RCS by two parallel pairs of motor-operated valves (MOVs) arranged in series.
These valves are interlocked to ensure redundant isolation of the RCS from the lower design pressure (600 pounds per square inch gauge [psig]) RHR system.
The Technical Requirements Manual requires that the valves be closed and deenergized before raising RCS pressure to 2 425 psig.
Plant operating instructions require that these MOVs be closed before RCS pressure exceeds 370 psig or 350 degrees Fahrenheit (F).
During performance of the Section XI inservice hydrostatic pressure test, the RCS would be E-2
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 brought to system normal operating pressure of approximately 2,235 psig, at which time the subject piping segments are isolated from the RCS by their respective check valves, or FCV-74-1 and FCV-74-9 in the RHR segment.
No method that is in compliance with the plant design and Technical Specifications and which does not require the redesign of the RCS system piping is available to pressurize these piping segments to full test pressure during the Section XI hydrostatic pressure test.
Three methods which were investigated are: (1) the use of temporary high pressure hoses connected to RCS test connections, vent or drain piping to "jumper" around the isolation valves
[where such connections exist], (2) the use of hydrostatic pumps connected to each piping segment [where connections exist], and (3) opening 1-FCV-62-84 and initiating Auxiliary Spray for the Auxiliary Spray line.
Methods (1) and (2) conflict with plant design requirements and 10 CFR 50.55a(c)(2)(ii) by eliminating the double isolation boundary required for the reactor coolant pressure boundary when the reactor vessel contains nuclear fuel.
Method (3) has two significant issues.
First, opening 1-FCV-62-84 and initiating Auxiliary Spray will cause the expenditure of one of ten of the thermal stress cycles for which the nozzle associated with this line has been analyzed.
Second, initiating Auxiliary Spray will adversely impact RCS pressurizer pressure control in that it will cause a reduction in pressurizer pressure.
If the valve fails to reclose immediately, there is a significant probability that the action will result in a safety injection actuation based on low pressurizer pressure.
The use of any of these methods would require a redesign of the RCS and the installation of new piping designed to meet the plant construction code and licensing commitments.
This option imposes a burden to TVA which is not commensurate with the increase to plant safety achieved through compliance with the ASME Section XI pressure test requirement versus use of the proposed alternative test method.
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ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 The purpose of the ASME Section XI pressure test is to detect existing through-wall defects in the pressure retaining boundary by the identification of leakage from the boundary.
The detection of pressure boundary leakage from such through-wall defects can be achieved at pressures lower than the pressure associated with 100% rated reactor power.
The proposed alternate testing method will achieve the greatest test pressure in each piping segment listed in the attached Table 1 which can be achieved without plant modification, and while in compliance with plant Technical Specifications and design requirements when nuclear fuel is contained in the reactor.
The difference in the amount of leakage (Lp) at the proposed test pressure (Pp) versus the amount of leakage (LXI) at the ASME Section XI required test pressure (PXI) is estimated by the following equation:
Lp = (LxI) X (Pp/Px1)
Where Pxl = 1.02% of the nominal operating pressure associated with 100% rated reactor power
= (1.02)(2,235) psig
= 2,280 psig.
For the proposed test method for the safety injection system piping the expected leakage from a through wall defect would be approximately:
Lp = (Lxl) x (1500/2280)% = LxI x 0.81 or, 81% of the leakage at the higher Section XI test pressure.
For the proposed test method for the RHR system piping the expected leakage from a through wall defect would be approximately:
Lp = (Lx1) x (350/2280)% = LxI X 0.39 E-4
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 or, 39% of the leakage at the higher Section XI test pressure.
The Section XI test procedure requires a holding time (4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated components and 10 minutes for non-insulated components) after attaining test pressure in order to allow sufficient fluid leakage to collect to ensure detection by the visual, VT-2, examination.
The estimated reduction in the amount of leakage from a through wall defect would not be expected to prevent detection of the leak during the visual examination, nor justify the hardship of performing modifications to the RCS in order to comply with the Section XI test pressure requirement.
Proposed Alternative Test Method: The piping segments in the flow path from the Cold Leg Accumulator outlet isolation valve to the RCS cold leg piping will be pressurized using the accumulators to 2 610 and < 660 psig as required by the WBN Technical Specifications.
The Technical Specifications also require that the outlet isolation valves [MOVsI be fully opened, which aligns this piping to the RCS, whenever the RCS pressure is greater than 1000 psig.
The piping segments from the high pressure and intermediate pressure safety injection system and the safety injection accumulators will be pressurized using the safety injection pumps to approximately 1500 psig which is the pressure achieved with the safety injection pumps running in the minimum recirculation flow mode.
The piping segments from the RHR system segment will be pressurized to approximately 350 psig and visually examined when the RHR system is providing shutdown cooling during plant startup following the refueling outage.
The piping segment in the auxiliary spray line will be examined at the pressure existing between the isolation valve 1-FCV-62-84 and the check E-5
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 valve 1-CKV-62-661.
There are no test connections within this piping volume that will permit measurement of the pressure trapped between these two valves.
Therefore, the exact pressure present in this line cannot be predicted or measured without initiating auxiliary spray.
The pressure is bounded by the following two limits.
First, if 1-CKV-62-661 has any seat leakage, then the line will be pressurized to RCS pressure via seat leakage through the check valve.
This is considered the most probable case.
- However, if 1-CKV-62-661 is absolutely leak tight [i.e., no seat leakage],
the pressure between 1-FCV-62-84 and 1-CKV-62-661 could be as low the pressure existing in the line the last time auxiliary spray was used.
Auxiliary spray is normally used during routine plant startup to provide pressurizer pressure control prior to starting a reactor coolant pump (RCP).
Once a RCP is started, pressurizer spray is available from its normal source and auxiliary spray is closed.
The minimum pressure at which an RCP may be started is 325 psig.
Although the pressure in the auxiliary spray line would be somewhat higher than this due to piping friction, this pressure is assumed to be the lower bounding limit for the pressure in this line.
This proposed alternative provides an acceptable method of testing the pressure boundary integrity of the segments identified in Table 1 while maintaining compliance with plant design requirements, plant Technical Specifications, and the requirement of 10 CFR 50.55a(c)(2)(ii).
By providing sufficient test pressure in conjunction with the test pressure holding time to allow detection of leakage from the pressure retaining boundary of the subject piping segments, this alternative provides an acceptable level of quality and safety.
Therefore, public health and safety would not be jeopardized by the granting of this relief request.
Duration:
This relief request is applicable to the First Inservice Period for Watts Bar Nuclear Plant, which ends on December 26, 2006.
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ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 TABLE 1 -
PIPING SEGMENT DESCRIPTIONS Nom.i=
,.5.
inahl~g> t l
m l
pirigle/lPr u,
Sapt injectio Accumulator No.........
1 Du Diameter Leng...
pe r.s.u.e.re.s..
eat..olat yte
.o isolation valve to outlet check valve (FCV-10 23 610-660 63-118 to CKV-63-622)
(Ref:_C/N_83015;_Dwg._E-2879_IC-89) 140____
Safety injection Accumulator No. 1 outlet14 check valve to Loop 1 cold leg (CKV-63-622 118SA-37 6
to CKV-63-560) 118 Type 316 (Ref:_c/N_83015;_Dwg._E-2879_IC-89)
Low pressure safety injection from RHR system CKV-63-633 to the 10 inch Loop 1 6
23 cold leg injection line (Ref: C/N 83015; Dwg. E-2879 IC-89)
High pressure safety injection piping from the 3 inch common header from CKV-63-581 to Loop 1 cold leg piping to CKV-63-586 1*,
123 2485 (Ref: Weld Maps 435-6 Sheet 3 and 435-7 Sheets 16-17; 47W435-7) 1500 Safety Injection pump piping from CKV-63-543 to the 8 inch Loop 1 hot leg injection line 2
1605 (Ref: Weld Map 435-7 Sheet 6)
Safety Injection pump piping from CKV-63-551 SA-376 to the 6 inch Loop 1 cold leg injection line 2
10 Type 304 (Ref: Weld Map 435-7 Sheet 2)____
Low pressure safety injection from RHR 82 system CKV-63-640 to the Loop 1 hot leg 82 injection CKV-63-641 (Ref: C/N 83015; Dwg. E-2879 IC-54) 6 2
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ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
UNIT FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 1
TABLE 1 -
PIPING SEGMENT DESCRIPTIONS Nomi....al...Pi.......
Pipe Sgment esign Proposd Tes Diaete.Ppe.enth.ipe Prssue resur Descrptio (inces) chedle (fet).ateral.(pi..
p.i.
Safety injection Accumulator No. 2 outlet isolation valve to outlet check valve (FCV-10 16 610-660 63-98 to CKV-63-623)
(Ref: C/N 83015; Dwg. E-27879 IC-90) 140 Safety injection Accumulator No. 2 outlet check valve to Loop 2 cold leg (CKV-63-623 10 15 SA-376 2485 to CKV-63-561)
Type 316 (Ref: C/N 83015; Dwg. E-27879 IC-90) 1500 Low pressure safety injection from RHR system CKV-63-632 to the 10 inch Loop 2 6
160 12 cold leg injection line (Ref: C/N 83015; Dwg. E-27879 IC-90)
High pressure safety injection piping from the 2 'A inch common header from CKV-63-581 to Loop 2 hot leg piping to CKV-63-587 11, 107 SA-376 (Ref: Weld Maps 435-8 Sheet 14 and 435-9 Type 304 Sheet 1)
Tp 0
Safety Injection pump piping from CKV-63-547 2
30 to CKV-63-559 (Ref: C/N 83015, Dwg. E-2879 IC-90; Weld Map 6
0.5 SA-376 435-8 Sheet 13) 160 Type 316 2485 1500 Safety Injection pump piping from CKV-63-553 to the 6 inch Loop 2 cold leg injection line (Ref: Weld Map 435-8 Sheet 6) 2 21 SA-376 Type 304 E-8
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 TABLE 1 PIPING SEGMENT DESCRIPTIONS NominalnI iipin Dimee P>>>
^
l ipe0 Legt Pipe = lS.Prs reP sur Des§:,n Criptl:
(inche) lchdule (fet Maera (pi)
(s
.:::~::f~:.ic Coolan System Loo 3
17 ype31 L
p uafety injection frcumulatorNom R3 o
sys80 te CKV-63-634tothe:10inchLoop.
Safety injection Accumulator No. 3 outlet isoltio valve to Loutle chckl valv (C
FCV6-6 10 17 610660 6380t CKV6-563)
Tye431 (Ref: C/N 83015; Dwg. E-2879 IC-91) 140__
Low pressure safety injection from RHR system CKV-63-634 to the 10 inch Loop 3 6
17 cold leg injection line (Ref: C/N 83015; Dwg. E-2879 IC-91) 2485 High pressure safety injection piping from 1'h CKV-63-581 to Loop 3 cold leg piping to CKV-63-588 2'A (Ref: C/N 83015; Dwg. E-2879 IC-86; Weld Map 435-9 Sheet 2) 3 Safety Injection pump piping from CKV-63-545 to the 8 inch Loop 3 hot leg injection line 2
(Ref: Weld Map 435-8 Sheet 9) 39 1500 83 160 20 SA-376 Type 304 7
20 Safety Injection pump piping from CKV-63-555 to the 6 inch Loop 3 cold leg injection line 2
(Ref: Weld Map 435-9 Sheet 4)
Low pressure safety injection from RHR system CKV-63-643 to the Loop 3 hot leg injection CKV-63-644 8
160 42 SA-376 2485 1500 (Reduces to 6" NPS at the inlet to CKV 8104 Type 30424510 644]
(Ref: C/N 83015; Dwg. E-2879 IC-55)
I I
I I
I E-9
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
WATTS BAR NUCLEAR PLANT (WBN) UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 TABLE 1 -
PIPING SEGMENT DESCRIPTIONS
_ J
.i DSafete inrectire AcrelaorNoureule Dcrton(Tinches Schedule (fet)
Material pi)(sg
- RecoriCoolant: -'Sys~tem Lo Safety injection Accumulator No. 4 outlet isolation valve to outlet check valve (FCV-22 610-660 63-67 to CKV-63-625)10260-0 (Ref: C/N 83015; Dwg. E-2879 IC-92)
Safety injection Accumulator No. 4 outlet 140 check valve to Loop 4 cold leg (CKV-63-625 10 24 SA-376 to CKV-63-563)
Type 316 (Ref: C/N 83015; Dwg. E-2879 IC-92)
Low pressure safety injection from RHR system CKV-63-635 to the 10 inch Loop 4 6
21 cold leg injection line (Ref: C/N 83015; Dwg. E-2879 IC-92)
High pressure safety injection piping from the 3 inch common header from CKV-63-581 to 11l Loop 4 cold leg piping to CKV-63-589 (Ref: Weld Map 435-6 Sheet 4)
Safety Injection pump piping from CKV-63-549 2
to CKV-63-558 in the 6 inch Loop 4 hot leg injection line (Ref: C/N 83015; Dwg. E-2879 IC-92; Weld Map 6
435-6 Sheet 1) 160 25 SA-376 Type 304 44 0.5 SA-376 Type 316 2485 1500 Safety Injection pump piping from CKV-63-557 SA-376 to the 6 inch Loop 4 cold leg injection line 2
7 Type 304 (Ref: Weld Map 435-6 Sheet 9)
Type 304 RHR piping between FCVs-74-1 and 8 and FCVs-10 22 SA-376 74-2 and 9 140 (Ref: C/N 83015; DWG. E-2879 IC-53) 14 140 316 350 X
f-Reactor Coolant S ystem Presuie E-10
ENCLOSURE TENNESSEE VALLEY AUTHORITY (TVA)
UNIT 1 FIRST 10-YEAR INTERVAL REQUEST FOR RELIEF ISPT-09 TABLE 1 -
PIPING SEGMENT DESCRIPTIONS i
i p d.Te s t Dimtr Pie Lnth Pp ressure"i P ressure D e c r p t o
( i n c h e s )
S c he d u l
( f e e t )
M a e r a
( p i g
( pl i g )
Auxiliary spray piping from 1-FCV-62-84 through 1-CKV-62-661 3
160 41 SA-376 2485 325 to 2235 (Ref: C/N 83015; Dwg. E-2879 IC-36; Weld Map Type 304 406-9, Sheet 17; 47W406-7 & -8)
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