ML20029D407
| ML20029D407 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 04/28/1994 |
| From: | Fox J GENERAL ELECTRIC CO. |
| To: | Poslusny C Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9405050322 | |
| Download: ML20029D407 (13) | |
Text
.
GENuclear Energy i..
[
GeneralElectnc Comeany I15 Cuttoet Avenue, sin Jose. CA S5125 April 28,1994 Docket No. 52 001 i
l l
Chet Poslusny, Senior Project Manager Standardization Project Directorate Associate Directorate for Advanced Reactors l
and License Renewal
- Office of the Nuclear Reactor Regulation
Subject:
Submittal Supporting Accelerated ABWR Schedule -
Suppression Pool Strainers
Reference:
(1)
Letter, Jack Fox to Chet Poslusny dated April 11,1994, Same Subject (2)
Letter, Jack Fox to Chet Poslusny dated April 14,1994, Same Subject
Dear Chet:
Enclosed is a revised SSAR markup addressinfhe recent interactions between GE and th the suppression pool strainer issue. This markup incor) orates References 1 and 2, and NRC. It is G3's belief that this markup addresses all of the NRC concerns and should be the basis of the final resolution.
l j
Please provide a copy of this transmittal to John Monninger.
Sincerely, bY Jack Fox Advanced Reactor Programs cc:
Alan Beard GE)
Norman Fletcher DOE)
Joe Quirk GE Craig Sawyer Bill Taft l
l 030099 0 $
0 JNT48437 9405050322 940428 I\\
PDR ADOCK 05200001 C
23A6100 Rev 4 2-ABWR sizndzrd Sxtery Analysis Report 4
6C Containment Debris Protection for ECCS Strainers G C. I b en c k.yoww NRC Hulletin No. 9S02," Debris Plugging of Emergency Core Cooling Suction i
Strainers," references NRC guidance and highlights the need to adequately accommodate debris in design by focusing on an incident at the Perrv Suclear Plant.
i GE re.iewed the concerns addressed by NRC Bulletin 9S02 and has reviewed the design of the ABWR for potential weaknesses in coping with the bulletin's concerns. GE has determined that the ABWR design is more resistant to these problems for a number of cx cd hewa\\ q m d aw ca.
reasons as discussed in the following.
a s eks e A.z'd h Oo a.'T% e.
i The ultimate concern raised by the Perrvincid ntwas the deleterious effect of debris in the suppression pool and how it could impact e ability to draw water from the suppression pool during an accident. The ABW design has committed to following the l
guidance provided in Regulatory Guide 1.82 and ABWRis designed to inhibit debris generated during a LOCA from preventing operation of the Residual Heat Removal (RHR), Reactor Core Isolation Cooling (RCIC) and High Pressure Core Flooder (HPCF) systems.
6 C. 2 A 8w R. ' M %aba) F M'^
- The ABWR has substantially reduced the amount of piping in the drywell relative to earlier designs and consequently the quantity ofinsulation required. Furthermore, there is no equipment in the wetwell spaces that requires insulation or other fibrous materials. The ABWR design conforms with the guidance provided by the NRC for maintaining the ability for long-term recirculation cooling of the reactor and containment following a LOCA.
E.
evelopment worus m progress by vanous organizations to achieve solutions of the
- t. >
ECCS strainers debds plugging problem. The ABWR design is committed to apply an acceptable solution as this issue becomes resolved. Selection ofinsulation, strainer design. pump features. and acolicable containment details will be addressed.
i IIw=The Perryincidentwas not the result of a LOCA but rather debds entering the l
Suppression Pool during normal operation. The arrangement of the drywell and wetwell/wetwell airspace on a Mark III containment (Peny) is significantly different from that utilized in the ABWR design. In the Mark III containment, the areas above the suppression pool water surface (wetwell airspace) are substantiallv covered by grating
, fi with significant quantities of equipment installed in these are,3 n these areas are no
[real carners w pdvent sman quantines of debns from falling into the suppress f from the spaces located above the pool surface. This arrangement contributes to a (much greater potential for debris to enter the suppress l
j as well as activities in the containment during power operationJL j
the wetwell airspace (contamment) of a Mark IIIis allowed dunng power operations. In contrast, on the ABWR the only connections to the suppression pool are 10 dnwell connecting vents (DCVs), and access to the wetwel{during power operations is og dv WILY
~
6C-1 Containment Debns Protection for ECCS Strainers - Amenoment 34
23A6100 Rev. 4
}
ABWR standard safety Anarysis Report prohibited.The DCVs will have horizontal steel plates located above the openings that will prevent any material falling in the dnwell from direct'.y entering the vertical leg of the DCVs. This arrangement is similar to that used with the Af ark 11 connecting vent pipes. Vertically oriented trash rack construction will be installed around the penpherv of the horizontal steel plate to intercept debris. The trash rack design slall allow for adequate flow from the dnwell to wetwell. In order for debris to ercer the DCV it would have to travel horizontally through the trash rack prior to falling into the vertical leg of the connecting vents. Thus the ABWR is resistant to the transport of debris from the i
drywell to the werwell.
in the Perrv incident, the insulation material acted as a sepia to filter suspended solids t
from the suppression pool water. The Afark I,11, and 111 containments have all used carbon steel in their suppression pool liners. This results in the buildup of corrosion products in the suppression pool which setde out at the bottom of the pool until they are stirred up and resuspended in the water following some event (SRV lifting). In contrast, the ABWRliner of the suppmssion poolis fabricated from stainless steel which significantly lowers the amount of corrosion products which can accumulate at the bottom of the pool.
Since the debris in the Perry incident was created by roughing filters on the containment cooling units a ccmparison of the key design features of the ABWR is necessary. In the Afark 111 design more than 1/2 of the containment cooling units are l
effectively located in the wetwell airspace. For the ABWR there are no cooling fan units in the wetwell air space. Furthermore the design of the ABWR Dnwell Cooling Systems j
does not utilize roughing filters on the intake of the containment cooling units.
In the event that small quantities of debris enter the suppression pool, the Suppression Pool Cleanup System (SPCU) will remove the debris during normal operation. The SPCU is described in Section 9.5.9 and shown in Figure 9.5.1.cf A.GY,T, SS.
he 3
l SPCU is designed to provide a continuous cleanup flow of 250 m /h. This flow mte is sufficiently large to effectively maintain the suppression pool water at the required purity. The SPCU system is intended for continuous operation and the suction pressure of the pump is monitored and provides an alarm on low pressure. Early indication of any deterioration of the suppression pool water quality will be provided if significant quantities of debris were to enter the suppression pool and cause the strainer to become plugged resulting in a low suction pressure alarm.
i I
( The ABWR will at a mimimum, size the ECCS suction strainers in accordance with Reg.i(
Guide 1.82 for all breaks required to be considered. Breaks invohing the Alain Steam Lines are expected to determine the strainer size per Reg. Guide 1.82. To address the uncertainty regarding the potential non<onservatism associated with the head loss Containment Debns Protection for E::S Strainers - Amenament 34 6:2 l
23As100 Rev ABWR P -2. 0 Standard Safety Analysis Report calculations performed for strainer sizing the following additional requirement will be met:
For breaks other than those invoking the main and RCIC steam systems, the RHR
(
suction strainers will have a constructed area at least 3 times the basic strainer
\\
surface area obtained from Reg. Guide 1.82. as required for the specific break under onsideration.
The sucdon strainers at Perry did not meet the current regulatoy requirements. The ABWR ECCS suction strainers will utilize a "T" arrangement with conical strainers on the 2 free legs of the "T". This design separates the strainers so that it minimizes the potential for a contiguous mass to block the flow to an ECCS pump. The ABWR design also has additional features not utilized in earlier designs that could be used in the highly improbable event that all suppression pool suction strainers were to become plugged. The alternate AC (Alternating Current) independent water addition mode of RHR allows water from the Fire Protection System to be pumped to the vessel and sprayed in the wetwell and drvwell from diverse water sources to maintain cooling of the fuel and containment. The wetwell can also be vented at low pressures to assist in Jooling the containment.
6 C A' Pi s cv s 3 s o
- 5 v w'e nv'v In summarv, the ABWR design m) cludes the necessaq provisions to prevent deoris impairing the ability of the RCIC, HPCF, and RHR systems to perform their required l N S EILT post-accident functions. Specifically, the ABWR does the following:
A (1) The design is resistant to the transport of debris to the suppression pool.
3
(;f) The SPCC system will provide early indication of any potential problem.
6 (3) The ECCS suction strainers meet the current regulatorv requirements unlike the strainers at the incident plants.
5 Q4) The equipment installed in the dnwell and wetwell minimize the potential for generation of debris.
i n addition to the ABWR design features. the control of the suppression pool cleanliness is a significant element of minimizing the potential for strainer plugging.
sh s a \\c IJ s h e (
o k$sw4.v-U-) D4 s'$.A p W t so nw,Rc p o. y A <
co-a4to-e -o. 6 c.4 1-ts whch ss
( 4 %e. s e cu s3,b o pv.Ao- %u %Ar s q p v-4.s n e w g o o l c L.o.v l t n e ss.
5 V" G! V~f M kI "f f
[~7) % g., R,f4l1. 5uc., bow o.d.c( hoem l Ma. cdo r-o-F s d e sg n vw M i n.
6: 3 :
Containtnent Deons Prctection for ECCS Strainers - Amencenent 3
.. ~~
I N SERT A
~
.D r~ gvove whY d C. 3 R.G
- 1. B '2.
All ECCS / trainers will at a minimum be sized to conform with the guidance provided in Reg Guide 1.82(Rev.1) for the most severe of all postulated breaks.
T The following clarifying assumptions will also be applied and will take precedence:
O)
The debris generation model will utilize right angle cones acting in be h directions; (z)
The amount of insulation debris generated will be assumed to be 100%
of the insulation in a distance of 3 IJD of the postulated break within the right angle cones including targeted insulation; b)
All of the insulation debris generated will be assumed to be transported to the suppression pool; (4)
The debris in the suppression pool will be assumed to remain suspended until it is captured on the surface of a strainer.
The sizing of the RHR suction strainers will assume that the insulation debris in the suppression poolis evenly distributed to the 3 pump suctions. The strainer size will be determined based on this amount of insulation debris and then increased by a factor of 3. The flow rate used for calculating the strainer size will be the runout system flow rate.
The sizing of the RCIC and HPCF suction strainers will conform to the guidance of Reg Guide 1.82 and will assume that the insulation debris in the suppression pool is proportionally distributed to the pump suctions based on the flow rates of the systems at runout conditions. The strainers assumed available for capturing insulation debris will include 2 RHR suction strainers and a single HPCF or RCIC suction strainer.
6C.5 Strainer Sizing Analysis Summary A preliminary analysis was performed to assure that the above requirements could be satisfied using strainers compatible with the suppression pool design as shown by Figure 1.2-13i.
The following summarizes the results, which indicate strainer sizes that are acceptable within the suppression pool design constraints.
Each loop of an ECCS system has a single suppression pool suction strainer configured in a T shape with a screen region at the two ends of the T cross member.
Analysis determined the area of each screen region. Thus, RHR with three loops has six screen regions. The HPCF with two loops has four screen regions, and the RCIC has two screen regions.
The characteristic dimension given for the screers in the results below indicates a surface area consisting of a circ., with a diameter of the dimension plus a cylinder with a diameter and length of the dimension.
By the requirements above, all of the debris deposits on the strainers.
The distribution of debris volume to the strainer regions was determined as a fraction of the loop flow splits based on runout flow.
Debris on the screen creates a pressure drop as predicted by NUREG-0897, which is referenced by R.G.1.82.
The equation for NUKON insulation on page 3-59 of NUREG-0897 was used for this analysis.
The NUKON" debris created pressure drop equation is a function of the thickness of debris on the screen (which is a function of debris volume), the velocity of fluid passing through the screen (runout flow used), and the screen area.
The debris created pressure drop was applied in an equation as follows; the static head at the pump inlet is equal to the hydraulic losses through the pipe and fittings, plus the pressure drop through the debris on the strainers, plus the hydraulic loss through the unplugged strainer, plus a margin equal to approximately 10% of the static head at the pump inlet, and plus the required NPSH.
The static head takes into account the suppression pool water level determined by the draw down calculated as applicable for a main steam line break scenario.
A summary of the applicable quantitative information input is provided in Table 6C-1, and a summary of the analysis results is provided in Table 6C-2.
1 6C.5 Strainer Sizing Analysis Summary. (continued)
By making realistic assumptions, the following additional conservatisms are likely to occur, but they were not applied in the analysis.
No credit in water inventory was taken for water additions from feedwater flow or flow from the condensate storage tank as injected by RCIC or HPCF. Also, for the long term cooling condition, when suppression pool cooling is used instead of the low pressure flooder mode (LPFL), the RHR flow rate decreases from runout (1130 3
3 m /h) to rated flow (954 m /h), which reduces the pressure drop l
across the debris.
l l
4 Table 6C-1 Debris Analysis Input Parameters 3
Estimated debris created by a main steam line break 2.6 m.
3 RHR runout flow (Figure 5.4-11, note 13) 1130 m /h 3
HPCF runout flow (Table 6.3-8) 890 m /h 3
RCIC controlled constant flow (Table 5.4-2) 182 m /h 3
Debris on RHR screen region, 3 RHR loops operating 0.434 m.
3 i
Debris on HPCF screen region 0.369 m.
3 Debris on RCIC screen region 0.097 m.
j RHR required NPSH (Table 6.3-9) 2.4 m HPCF required NPSH (Table 6.3-8) 2.2 m RCIC required NPSH (Table 5.4-2) 7.3 m l
RHR pipe, fittings and unplugged strainer losses
- 0.60 m HPCF pipe, fittings and unplugged strainer losses
- 0.51 m RCIC pipe, fittings and unplugged strainer losses
- 0.39 m Suppression pool static head above pump suction 5.05 m
- Calculated hydraulic losses Table 6C-2 Results of Analysis 2
RHR screen region area / characteristic - dimension 5.66 m / 1.20 m 2
HPCF screen region area / characteristic dimension 1.46 m / 0.61 m 2
RCIC screen region area / characteristic dimension 0.27 m / 0.26 m 2
Total ECCS screen region area 40.0 m l
23A6100 Rzv. 4 ABWR stand:rdSktyAn1IysisRip rt l
Table 6.2 2b Net Positive Suction Head (NPSH) Available to RHR Pumps 1
A.
Suppression pool is at its minimum depth, El. -3740 mm.
B.
Centerline of pump suction is at El.-7200 mm.
C.
Suppression pool water is at its maximum temperature for the given operating mode,100*C, D.
Pressure is atmospheric above the suppression pool.
Minim u.rn.
E.
cx; E. dix Cm suction st(ainer!cerer re 0.21.T o-re.o. os comm'i~tte.d to by APPe me.T ods NPSHq HATM + Hs -HVAP -Hp where: a.va.11a ble HATM = Atmospheric head Hs
- Static head HVAP = Va r pressure head mum Hp ional head including strainer aJloWed Minimum Expected NPSH 3
RHR Pump Runout is 1130 m /h.
Maximum suppression pool temperature is 100*C.
HATM =10.78 m Hs
=3.46m HVAP =10.78m Hp
=e-esm- 0,78 m 0 71 NPSH available = 10.78 + 3.46 - 10.78 -DJiHr= 2:66rrr 2.. 7f m NPSH required = 2.4m
,fp
-p p_ "_ ^]M ^_A
.p Margin.0,35M =. NPSNgy,,-l,,gl, - NfggrgdrQ I
l Contasnment Systems - Amendment 34 6.2 107 I
23A6100 Rev. 4 ABWR sundardStfety Analysis Rip:rt i
i Table 6.3-9 Design Parameters for RHR System Components (Continued)
(4) Type water Reactor Building Cooling Water (5) Fouling factor 0.0005 (3) Strainer (D008)
Location Suppression Pool Li pu.T.p NPOll icqu;cc..eas <<h= T' p!uggcd -
Size As rqu. ired for instdaflon. Abris pe.r-(4) Restrict.mg Orifices AP P6d* M Location (D003)
Vessel return line 3
l Size Limit flow to vessel to 954 m /h Location (D002)
Suppression pool return line 3
l Size Limit flow during suppression pool cooling to 954 m /h Location (D004)
Fuel pool return line 3
l Size Limit flow during fuel pool cooling to 350 m /h Location (D001)
Pump minimum flow line 3
l Size Limit pump flow through the bypass line to 1453 m /h Location (D005)
Discharge line to wetwell spray 3
l Size Limit wetwell spray sparger flow to 114 m /h Location (D006)
Discharge line to drywell sparger 3
l Size Limit drywell spray sparger flow to 840 m /h (5) Flow Elements (FE009)
Location Pump discharge line, downstream of heat exchanger bypass return 3
l Rated Flow 954 m /h 6.1m w.g. maximumh 954 m /h 3
l Head Loss Accuracy 2.5% combined element, transmitter and indicator at rated flow (6) Vessel Flooder Sparger 3
l Flow Rate 954 m /h 3
l Minimum Exit Velocity 11 m/s @ 954 m /h (7) Wetwell Spray Sparger 3
l Flow Rate 114 m /h (8) Drywell Spray Sparger 3
l Flow Rate 840 m /h Emergency Core Cooling Systems - Amendment 34 6.3-37
I*
23A6100 Rev. 4 ABWR Stand:rdS:hty An: lysis R:pirt Table 6.2-2c Net Positive Suction Head (NPSH) Available to HPCF Pumps A.
Suppression pool is at its minimum depth, El.-3740 mm.
B.
Centerline of pump suction is at El.-7200 mm.
C.
Suppression pool water is at its maximum temperature for the given operating mode,100'C.
D.
Pressure is atmospheric above the suppression pool.
Minimarrs E.
fdammum. suction strainqr k ::: : : 0.5r o.re_a a.S commi tted to by A P P GndiX bC F"GJho 5,
NPSH =HATM + Hs -HVAP - F C Vd I IA b! @-
where:
HATM
= Atmospheric head Hs
= Static head HVAP
= vapor pressure head Mo.ginfhead including strainer a.lloWE d m
Hp
=4Frictiona Minimum Expected NPSH 3
HPCF Pump Runout is 890 m /h.
Maximum suppression pool temperature is 100*C HATM
= 10.78m Hs
= 3.46m HVAP
= 10.78m Hp
= 1.02 r, 0 9) m O,9 i NPSH available = 10.78 + 3.46 - 10.78 -W = 2.44.T.
- 2.,5E m NPSH required = 2.2m
^
^
y;,,
f_^
- pf;p Af s,27s,,
Margirl 6.38 O M8Ma.va_ila.ble. - NPS#reydred l
i 6.2 108 Containment Systems - Amendment 34
l**
23A61C0 Rev. 4 ABWR Stwdttd Sility An: lysis Rtport Table 6.3-8 Design Parameters for HPCF System Components (1) Main Pumps (C001)
Number of Pumps 2
Pump Type Centrifugal Drive Unit Constant sped induction motor 3
l Flow Rate 182 m /h @ 8.22 MPaA reactor pressure 3
l 727 m /h @ 0.79 MPaA reactor pressure
- l Developed Head 890m @ 8.22 MPaA reactor pressure l
190m @ 0.79 MPaA reactor pressure 3
l Maximum Runout Flow 890 m /h @ 0.10 MPaA reactor pressure 3
l Minimum Bypass Flow 73 m /h Water Temperature Range 10 to 100*C+
NPSH Required 2.2 m (2) Strainer (D001)
Location Suppression Pool Size 40 '_ p!u;;;d f.c" meet pur,p NPC" :qwicpc,Ja Y
(3) Restricting Orifice (D002)
A Pendix LC-P Location Pump discharge line Size Limit pump flow to values specified 3
(4) Condensate Storage Tank 570 m reserve storage for HPCF and RCIC Systems combined (5) Flow Elements (FE008)
Location Pump discharge-downstream of minimum flow bypass line 3
[
Head Loss 6.1m w.g. maximum @ 727 m /h Accuracy 2.5% combined element, transmitter and indicator at maximum rated (6) Core Rooder Sparger 3
l Flow Rate 727 m /h minimum @ 0.79 MPaA reactor pressure 3
l Pressure Drop 50m w.g. maximum @ 727 m /h (7) Piping and Valves l
Design Pressures 0.31 MPaG-suction and discharge connected to suppression pool l
2.82 MPaG-pump suction l
10.79 MPaG-pump discharge i
6.3-34 Emergency Core Cooling Systems - Amendment 34 i
23A6100 Rev. 4 ABWR Scad:rdSnityAn:lysisRip rt 4
Table 5.4-1a Net Positive Suction Head (NPSH) Available to RCIC Pumps A
Suppression pool is at its minimum depth, El. -3740 mm.
Centerline of pump suctiorNs at El.-7200 mm.
B.
C.
Suppression pool water is at its maximum temperature for the given operating mode,77'C.
Pressure is atmospheric above the suppressionpool.d to by D.
Minymum a.v e.a. a.s co mmi tt e E.
- /=: mum suction strainer !ccree 2rc ' '"m '50% P';;cd Append 1x C. m e. hods.
Npsy = HATM + Hs - HVAP - Hp 8
aUE where Atmospheric head HATM
=
h.,
Static head Hs
=
Vapor pressure head HVAP
=
bt on$1 head including strainer a.Ilok/e.d T
Hp
' =
Minimum Expected NPSH 3/
RctC emp flow is 182.m/h Maximum suphression pool temperature is 77'C 10 72G IO*b2 Yh HATM 3.46m Hs
=
D 4' 3 M
(
HVAP
+BBm-2.,10 Hp
=
t
, 4 e-o-
l
- ;; g.,g, u i- _
10 61 4,33 2.10 NPSH available = 1976 + 3.46 -$22-t92 = 045m-7,6f m l
l NPSH required = 7.3m v y ; / _ ^ ; % ; ; < m v _ -j y-4Pf /~Re&
l w
Ma.cgin= o.35m c. NPS#agldle-NPS4regdred I
$/PsH Tfebence. Pc, int l
)
i 1
5.4-60 Component and Subsystem Design - Amendment 34 l
w-n
-,,,, -