ML20116L388
| ML20116L388 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 10/08/1992 |
| From: | Fox J GENERAL ELECTRIC CO. |
| To: | Poslusny C Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9211180288 | |
| Download: ML20116L388 (13) | |
Text
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oo October 8, 1992 Chet Posiusny, Senior Project Manager Standardization Project Directorate Associate Directorate for Advanceo Reactors and '.icense Renewal Office f Nuclear Reactor Regulation
Dear Chet:
Subjcci: PROPOSED RESOLUTION OF ISLOCA ISSUE FOR ABWR Enclosed is the subject document induding modified P& ids for the affected systems.
Following NRC staff review and -approval of the proposed ISLOCA resolution, GE will prepare a corresponding modification to Subsection 19B.2.15, High/ Low Pressure Interfecc Design.
Sincerciv, y
ja Fox Advanced Reactor Programs ec: George 'i homas 1T 132 t
h
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19OPOSilD_lui&Ql,UTION OF ISi OCA ISSUESf03 ABWRm In t rod u c.limt An intersystem loss of coolant accident (ISLOCA) is post ted to occur when a series of failures or inadvertent actions occur that allow the high pressure from one system to be applied to the low pressure design of another system, which could potentially rupture the pipe and loose coolant.
from the reactor system pressure boundary.
This may also occur _ within the high - and low pressure portions of a single system.
Future ALWR ' designs like the A13WR are expected to reduce the pose'ility of a LOCA outside the containment by designing to the extent p.
..eable all systems and subsystems connected to the RCS to an ultimate rupture strength (URS) at-least equal to the fu l RCS pressure. The URS l
criteria was recommended by the Reference I and by recent discussions with the NRC Staff to determine low pressum piping's design pressure to o atain ISLOCAs.
Evaluation Procedure The pressure of each system piping soundary on all of the ABWR P&lD's -
was reviewed to identify 'where changes were needed to provide :URS protection.
Where low pressure piping interfaces with higher pressure piping connected to piping with reactor cc olant at reactor pressure, pressure values were increased to 24.6 atg which is equivalent to 350 psig.
(I a. = 1 kg/sq cm; atg is gauge)
The low-pressure piping boundaries upgraded to UllS pressures extend to the. last closed valve connected to piping interfacing a low pressure sink, such; as the suppression pool,.
condensate storage tank or. other open configuration (identified tank).
Each interf9eing system's: piping was review;d for upgrading and in. some with low pressure piping with normally open valves were changed to lock open valves to: insure an open piping pathway frrm the:last primary systmi closed valve to the tank or -low pressure sii,k.-
^
wr ie
ISLOCA 2
10/8/92 Typical systems for this upgrade include the:
- 1. Radwaste LCW and IICW receiving tank piping, 2 Fuel Pool Cooling System's RIIR interface piping connected to the skimmer surge tanks,
- 3. Condensate Storage System's tank locked open supply valves,
- 4. Makeup Water Condensate and Makeup Water Purified Systems with locked open valves and pump bypass piping to the Condensate Storage Tank.
All test, vent and drain piping was upgraded where it interfaces with the piping upgraded to URS pressure.
Similarly, all instrument and relief valve connecting piping was upgraded. P&lDs refere. icing ABWR SSAR Figuies were marked with the new pressure boundary values identified with
" clouds" and-heavy piping lines to show the. upgraded piping, equipment and instruments.
Boundary Limits of URS The boundar; limits of the URS design were established r.ssuming slow rates of leakage between high and low pressure regions.
This means only static pressurization needs to be considered and low pressure sinks.do not pressurize This also means the piping between the valve adjacent to a low -
pressure sink and the low pressure sink does not pressurize; therefore, it i
can be assumec such a valve remains closed.
The components considered to be low pressure sinks in this evaluation are:
(1) SuppIgnign Pool - Provides a low pressure sink (just-above atmospheric) for its interfacing systems and the first closed valve is at least 24.6 atg (350 psig) rated.
(2) Condensate Storage Tank -- Vented' to atmosphere and its locked open valves and stainless steel pipin;, insure it is a low pressure sink for its interfacing systems.
The first closed vahe of each interfacing system with URS upgrade is at least 24.6 atg (350 psig) rating.
I I
ISLOCA 3
10/8/92 (3) SI.C main tank - Vented to atmosphere with the first closed valve at least 24.6 atg (350 psig) rating.
(4) LCW Receiving Tank - Vented to atmosphere, and the first closed valve is at least 24.6 atg (350 psig) and one of the tank's dual valves is locked open.
(5) EV Rtc_civing Tank - Vented to t.tmosphere, and the first closed valve is at least 24.6 atg (350 psig) and one of the tank's dual valves is locked open.
Sysiq11u Evaluated The following twelve systems, interfacing directly or indirectly with the RCS, were evaluated.
SSAR Figure No.
Residual IIcat Removal (RIIR) System 5.4-10 liigh Pressure Core Flooder (llPCF) System 6,3-7 Reactor Cere Isolation Cooling (RCIC) System 5.4-8 Control Rod Drive (CRD) System 4.6-8 Standby Liquid Control (SLC) System
-9.3-1 Reactor Water C!aant, (CUW) ' System 5.4-12 Fuel Pool Cooling Cleanup (FPC) System 9.1-1 Nuclear Boiler (NB) System S.1-3 Reactor Recirculation (RRST System 5.4 (
Makeup Water (Condensate) (MUWC) System, 9.2-4 l
Makeup Water-(Purified) (MUWP) System.
9.2-5 l
Radwaste System
-l1.2-2 (LCW Receiving Tank,- HCW Receiving Tank).
Einbig Design Prpssure for URS Coruoliance The full URS condition is illustrated on Figure 1 at the full reactor pressure L
L of 72.1 stg, 73.1 ata (1025 psig;-1040 p;ia) and the ultimate stress.
The j
straight line from this point to the coordinates origin establishes
?
ISLOCA 4
10/8/92 proportionality to the URS, which is valid since pressure and stress are-
- proportional.
Using an example of c:rbon steel with an ultimate stress of 4219 kg/cm2 (60' kpsi) and an allowable stress of 1055 kg/cm2- (15 kpsi),
the ultimate based-design pressure proportional to the allowable stress is 18 atg (256 psig). Thus for a pipe designed so that a 18 atg (256 psig) pressure produced the allowable 1055-kg/sq cm (15 kpsi) stress, then if an over pressurization of 72.1 atg (1025 psig) occurred in that pipe, its stress would rise to 4219 Kg/cm2 (60 kpsi), the ultimate strength.
Thus,18 atg (256 psig) represents an' ultimate based design stress that has no margin with respect to the-URS.
In this case tbc ratio-of allowabi: stress to ultimate stress is 15/60 = 0.25, which is the same as the ratio of design pressure to applied pressure, 256/1025 = 0.25.
To use a design stress that has a reason.,ble margin with respect to the full URS, a ratio of 0.33 is utilized instead of 0.25.
A ratio of 0.33 produces a desi9.n pressure of 24 atg (342 psig), which when nomin. ally rounded up gives a 24.6 atg '(350 psig) design pressure.
For a pipe designed just for the 24.6 atg (350 psig) design pressure, an applied pressure-of 98.5 atg (1401 psig) would be necessary to reach the full ultimate stress of 4219 kg/cm2 (60 kpsi).
It is useful to incorporate a safety factor into the discussion as a menure of the design margin beyond a full URS condition.
A safety factor definition is:
S. F. =
Load that would cause failure Service load imposed S. F. =
1401 osig = 1.367 1025 psig And by proportiona'ity S.F.=
150 osig
= 1.367 256 psig It is of interest to show how this relates to Service Level D of the ASME l
Code (Section III, NC-3611.2(c)(3)). For Service Level D, Pmax can be 2.0 times P.
With Pmu = 72.1 atg (1025 psig), the design pressure, P, could _be 36.1 - atg (513 psig).
For a design pressure of 36.1 atg (513 psig), the safety factor per the above is
ISLOCA -
5_
10/8/92 S.F.=
513 psig
= 2.00 (Service Level D) 256 psig The safety factor is 1.00 at the " ultimate based design pressure,"'see Figure 1, with a design pressure of 256.
The selection of the 24.6 atg (350 psig) design pressure resulted in a safety factor of 1.367, which was_ considered a placement to the -extent practical within the range between the ultimate based design pressure (S. F. = 1.00) and the Code service level D (S. F. =
2.00).
J With the design pressure selected, a minimum pipe wall thickness can be calculated using the ASME Code equation NC-3641.1 (3).
Results are shown for the range of pipe diameters in column F of Table 1.
tm = (P)(Do) + A 2(S +Py) whcre P=
Design Pressure S=
Allewable Stress y = 0.4 A=
Corrosion Allowance Do = Outside pipe diameter Next an actual pipe schedule wall thickness is selected as the next higher thicknes; from the calculat-d tm (colunm G of Table 1). The increased wall.
thickness (t, in the equation below) from tm Permits a higher pressure (Pa) than the initial design pressure when limited to the same. allowable stress.
This is called the allowable working pressure (Pa, equation below), which is calculated by the ASME Code equation NC-3641.1 (5).
The results are shown in columns I of Table 1.
Pa = 2S1 Do - 2y:
The SSAR design documentation satisfies IS~LOCA concerns by. imposing the 24.6 atg design pressure, which as used in piping design, will result in pipes with margins as shown in columns G through J.
However, if-the COL applicant selects standard pipe or increased wall thickness for -construction durability, even more ISLOCA protection will result.
Table 1, columns K through N, shows _ the analysis for standard pipe, STD, and the.next higher 1
->N--
w:
m
ISLOCA 6
10/8/92 pipe schedule for stainless.
This information is provided to illustrate the extra safety factor that could occur from the selection of-standard -pipe or thicker wVis for adequate construction durability.
The safety factor is calculatt :' in columns J and N for carbon steel pipe-(SA-333 Gr. 6) from P/256, where P is the permitted pressure (cclamns I or M) and the denominato-256 is:.
(1025M15) = 256 psig;
{J1ggetor full pressure)(Allowable stress)
=
.(Ultimate stress)
(60)
For stainless steel, between grades SA376 Type 316 SA312 Type 316 and SA358 Type 316,--
tFe properties of SA376 produce the lowest safety factor.
The P denominator for stainless is:
(1025 M I 8.4) = 251 (75)
Columns I and M for stainless steel is P/251.
For the stainless steel pipe, the diameter Do, was adjusted by Do/0.9 to l
account for greater ductility and_ pipe' swelling _ that occurs before rupture.
l Tne larger swelled diameter creates a higher stress on_ the wall-due to the increased pressure area.
The Do/0.9 value was provided from communication with Everit Rodabaugh, NRC consul ant.
t The corrosion allowance values in column C were-selected from the=
Pressure -Integrity of Nuclear Components specification listed on the ABWR-Certification Program master parts list 298X301CP. item-A11-3010.
L ApplicabPity of-URS Non-pioing CompF0h L
References 2 and 3 indicate the URS criteria also applies to associated-L flanges', connectors, packings, valve stem seals, pump. seals, heat exchanger tubes and valve bonnets.
i.
10/8/92 This is further illustrated in Attachment I which shows that the general membrane stresses for vessels, pumps and valves are equal or less ' than
-the allowable stress in all cases.
IIence. the basic ratio developed for-piping applies to vessels, pumps and valves.
Resulls Th results of this work are shown by the markups of the enclosed P& ids, which are SSAR figures.
The affected sheets are listed below.
System SSAR Affected Sheet Figure - No.
Nss Residual Heat Removal (RIIR) 5.4-10 1, 2, 3, 4 System liigh Pressure Core Flooder (IIPCF) 6.3-7 1, 2 System Reactor Core Isolation Cooling 5.4-8 1, 3 (RCIC) System l
Control Rod Drive (CRD) System 4.6-8 1, 3 Standby Liquid Control (SLC) 9.3-1 1
System Reacter Water Cleanup (CUW) 5.4-12 2
System
~
Fuel Pool Cochng Cleanup (FPC) 9.1-1 2
System l
Nuclear tioiler (NB) System 5.1-3 1, 5 Reactor Recirculation (RRS) 5.4-4 1
System lJ
.e
'ISLOCA 8
10/8/92 i
Makeup Water (Condensate) 9.2-4 1
(MUWC) System Mnkeup Water (Purified) (MUWP) 9.2-5 1, 2 System Radwastc System (LCW Receiving i1.2-2 3, 7 Tank, IICW Receiving Tank)
In addition, the following two systems were identified as requiring an ISLOCA evaluation.
Ilowever, these two systems are not in sufficient detail and this evaluation will be a requirement for the COI. applican:.
Condensate, Feedmter and Condensate Air Extraction (C,FDW,AO)-
System
'iampling (SAM) System The design pressure of t?: following two tanks was upgraded.
SLC test tank RCIC turbine barometric condenser tank Summarv
' For ISLOCA considerations,-a design pressure of 24.6 atg or (350 psig)
L provides an adequate. margin with respect to the full: reactor operating-pressure of 72.1 at.c 0025_ psig) by applyinq _ the ultimate rupture strength-(URS) methodology dsveloped by this work.
This : design pressure -was applied at the boundary symbols-of the P&lD figures, and therefore,
' impose tha requirement -on' the piping, vcives,- pumps, tanks, instrumentation and all other equipment shown between boundary symbols.
Upgrading-revisions were made to 14 systems.
I'
ISLOCA 9
10/8/92 References 1.
Dino Scaletti, NRC to Patrick Marriott, GE, " Identification of New Issues for the Ocneral Electric Company Advanced Boiling Water Reactor Review," Sep; ember 6,1991 2.
"American National Standard Forged Steel Fittii:gs, Sockets -
Welding and. Threaded,~' ANSI B16.11-1973, Sections 6.2 and 9.2.3.
3.
"BWR Owners Group Assessment of Emergency Core Cooling System Pressurization in Boiling Water Reactors," NEDC-31339, November 1986, Sections 3.2.2 and 3.2.3, on valve integrity and
-i heat integrity, respectively.
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500A 20 0.12 15000 350 0.3512 0.375 20 386.442 1.5081 0.375 20 386.442 1.5081 8
450A 18 0.12 15000 350 0.3281 0.375 429.872 1.6775 0.375...
429.872 1.6775 9 [400A 16 0.12 15000 350 0.3049, 0.312 20 363.489 1.4185 0.375 30 484.3 1.89 10 300A 12 0.12
.15000 350 0.2587 0.33 30 532.454 2.0779 0.375 648.526 2.5308 11 2503 10 0.12 15000 350 0.2356 0.'25 20 394.099 1.5379 0.365 10 749.694 2.9256 12 200A 8
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350 0.1894 0.28 40 817.439 3.19 0.28
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0.12 15000 350 0.1662 0.E37 40 898.525 3.5064 0.237 0
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0.12 15000 350 0.1431 0.154 40 517.032 2.0177 0.154 40 517.032 2.0177 17 18 19 STAIN 1.ESS STEEL 20 Next Std Thic 21 tm, in 22 23 500A 20 0.004 184_'
350.0.2138 0.25 spc' 411.016 1.6375 24 450A 18 0.004 18400 350 0.1928 0.25 spcl 457.138 1.8213 25 400A 16 0.004 18400 350 0.1718 0.188 10S 384.06 1.5301 26 300A 12 0.004 18400!
350 0.1299 J.156 5S 423.381 1.6863 0.18 10S 490.944 1.956 27 2_50A 10 0.00' 18400 350 0.10E9 0.134 SS 434.628 1.7316 0.165 10S 539.486 2.1493 i
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0.00, 18400 350 0.0879 0.109 SS -
438.847 1.7484 0.148 10S 603.988 2.4063 20 150A 6
0.004 18400 350 0.0669 0.109 SS 586.996 2.3386 0.134 10S 728.972' 2.9043 30 100A 4; 0.004 18400 350 0.046 0.083 SS 663.556 2.643G 0.12 10S 980.962 3.9082 l
31 80A 3
0.004 18400 350 0.0355 0.083 SS 889.016 3.5419 0.12 10S 1317.31 5.2483 32 50A 2
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'350 0.025 0.065 SS 1032.84 4.1149 0.109 10S 1807.11 7.1996 b
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ASME Code Reference; Ps, j 2, where
' NC.'640 PRESSURE DESIGN OF PIPING f,= mmimum required wall _ thickness. in'. If pipe pfpggg - PRODUCTS is ordered by its nominal wall thickness. the FC.3641 Straight Pipe P= internal Design Pressure, psi ts e ameter phe.
or des M d -
NC. 641.1 Straight Pipe Under Internal Pressurt.
The minimum thickness of pipe wall required for De.
- g.,;2ximum allowable stress for the mate:ial at sign Pressures and for *.emperatures not eaceeding the Design Temperature. ps; (Tables I.7.0) those for the vanous matertals listed in Tables !.7.0,
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- including allowances for mechanical strength. shall not
- ** E~ *Ide for material be less than that determmed by Eq. (3) as rellows:
{7 m
e s.
or e on-pp, y= a coeEicient having a value of 0.4, en:pt that,
- A (3) for pipe with a b,/t., rano less than 6, the
' " pS m
value of y shall be taken as
. (6) y=d+A VESSELS
"",= gen membrane stres, psi. This stress is NC.3321 1989 SECTION III, equal 'o the.werage stress across the solid sec:ic,n under con <idmtion. It eac!udes dis-TABLE NC-3321-1 c ntinuities and conce,ttrauens and is ;ro-STRESS LIMITS FOR DESIGN AND SERVICE LOADINGS 1 duced only by pressure and other tneehanical Semce unt Stress uv..ets [ Note (2)]
Desan ana tmi A
- e. s 1A 5 S= allowable stress value riven in Tables I-7.0,
'"* "* "* I esi. The allowable stress shall correspond to the highest metal temperature at the section under consideration during the loading under con <ideratier PUMPS NC.3416 NC.3000 - DESIGN NC.3c:3 TABLE hC-3416-1 STRESS AND PRESSURE LIMITS FOR DESIGN AND SERVICE LOADINGS Semca Stms LLwts P.,,
Urrut (Note (V)
(Note (2)!
Lewi A
- e. s 5 1.0 (e, or eil + e, c 1.35 VALVES NC 3330 1989 SECTION III, DIVISION 1 - NC NC.3531.4 TABLE NC-3521-1 LEVEL A. B. C, AND D SERVICE LIMITS 54mee Stms Urmu p
U*t INotes W-(41)
(Note (5)!
Lent A e
,, 3 1.0 te. or e l + r s 1.35 t
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