ML20065J701: Difference between revisions

From kanterella
Jump to navigation Jump to search
(StriderTol Bot insert)
 
(StriderTol Bot change)
Line 16: Line 16:


=Text=
=Text=
{{#Wiki_filter:g_                                                                                                                        .-
{{#Wiki_filter:}}
+ ...
(
GE Nuclear Energy Generst Dectne Ccmpany 175 Curtver Avenug San Jose. CA S$125 April 14,1994                                              Docket No. 52-001 Chet Poslusny, Senior Proj,ect Manager Standardization Project Directorate Associate Directorate for Advanced Reactors and License Renewal Office of the Nuclear Reactor Regulation
 
==Subject:==
Submittal Supporting Accelerated ABWR Schedule -
Suppression Pool Strainers i
 
==Reference:==
Letter, Jack Fox to Chet Posiusny dated April 11,1994, Sau Subject
 
==Dear Chet:==
 
Enclosed is a SSAR markup of Appendix 6C, addressing Open Item F6.2.1.9-1, which incorporates the agreed upor. Reference requirements and includes a sample calculation.
                                                                                                                          ~
If you should have any questions, please contact Alan Beard at (301)770-5985.
Sincerely, 3 Yo)4 Jack Fox Advanced Reactor Programs cc:          Alan Beard              GE)
Norman Fletcher          DOE)
Joe Quirk                GE                                                                          l Craig Sawyer            GE Dill Taft                G E, q
0 1${101u.~
                                                                                              .,y JN1W 433 9404190385 940414 PDR        ADOCK 05200001 A                        PDR
 
_ _ .      .                              m  . .                  _                      .
23A6100 Rev. 4
          ~
.    . ABWR                                                                            StandardSafety Analysis Report l
i 6C Containment De pris Protection for ECCS Strainers G C. I Back roec NRC          lletin No. 93-02, " Debris Plugging of Emergency Core Cooling Suction                  ]
Strainers," references NRC guidance and highlights the need to adequately accommodate debris in design by focusing on an incident at the Perg Nuclear Plant.                    ;
GE resiewed the concerns addressed by NRC Bulletin 93-02 and has reviewed the design                -)
of the ABWR for potential weaknesses in coping with the bulletin % concerns. GE has determined that the ABWR design is more resistant to these problems for a number of reasons as discussed in the following.
[ a ed howa\ q w d om eta s d as e rh      1 l
The ultimate concern raised by the Perry incidhnt was 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 prmided in Reg ilatory Guide 1,82 andg ABWRis designed toinhibit debris generated during a LOCA icom preventing operation of the Residual Heat Removal (RHR), Reactor Core Isolation Cooling (RCIC) and High Pressure Core Flooder                          ;
(HPCF) systems.
Gc.2TheAswR.                        m&a% Fdm ABWR has substantially reduced the amount of piping in the dqwell 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-tenn recirculation cooling of the reactor and containment following a LOCA.
evelopment work is in progress by various organizations to achieve solutions of the ECCS strainers debris plugging problem. The ABWR design is committed to apply an                      l acceptable solution as this issue becomes resolved. Selection ofinsulation, strainer                  l design, pump features, and applicable containment details will be addressed.
y IL.rcedhe Perry incident was not the result of a LOCA but rather debris entering the Suppression Pool during normal operation. The arrangement of the drywell and wetwell/wetwell airspace on a Mark III containment (Perry) 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 substantially covered by grating with significant quantities of equipment installed in these are3 din these areas are no (real tiarners to prevent small quantities of debris from falling into the suppression pool f from the spaces located above the pool surface. This arrangement contributes to a Yties I,(much greater potential for debris to enter the suppression poo as well as activities in the containment during power operation.lunherm re                cess to the wetwell airspace (containment) of a Mark IIIis allowed during power operations. In contrast, on the ABWR the only connections to the suppression pool are 10 dowell                      l connecting vents (DCVs), and access to the wetwelgduring power operations is og cf Wth Containment Debris Protection for ECCS Strainers ~ Amendment 34                                          6C-1
 
23A6100 Rev. 4
.        .      'ABWR                                                                          Standard Safety Analysis Report calculations performed for strainer sizing the following additional requirement will be m et:
For breaks other than those invohing 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 consideration.
The suction strainers at Perry did not meet the current regulatorv 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 addidonal 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 addidon mode of RHR allows water from the Fire Protection System to be pumped to the vessel and sprayed in the wetwell and dnwell from diverse water sources to maintain cooling of the fuel and containment. The wetwell can also be vented at low pressures to assist in cooling the containment.
GC.T 95 s cus3 %ow S u w'*9 In summary, the ABWR design mcludes the necessaq provisions to prevent debris from                        ;
impairing the ability of the RCIC. HPCF, and RHR systems to perform their required i N S ERT post-accident functions. Specifically, the ABWR does the following:
A                                                                                                                      <
l (1) The design is resistant to the transport of debris to the suppression pool.                      l 3                                                                                                  ;
()!) The SPCU system will provide early indication of any potential problem.
6
($) The ECCS suction strainers meet the current regulatorv requirements unlike                      -,
the strainers at the incident plants.                                                      i 5
(4) The equipment installed in the drywell and wetwell minimize the potential for generation of debris.
                              $ addition to the ABWR design features, the control of the suppression pool                                l clcanliness i                is a significant element of minimizing the potential for strainer plugging.-            f (M T h st $N gv4S t iow ' p o o k kiwCY"                is S d o w n \C fJ s h e lj udwch gg                kch            wAA M.<#o Co W o4tCW fo cd% C.
J.
g The s e cu s y s h o p voAa- w\\% dce Su g pv adstoW pook Ck4aMkk"888e
('7) h t,            R.MR. 5uckTOu 5 bG NM W 5 k \ " f f' a ck ck s hown ! Ma cdo v- oh '$ d C 3]^ M h} % n e Contamment Debris Protection for ECCS Sttsners - Amendment 34                                            GC T4
 
23A6100 Rev. 4 i    . A'BWR                                                                          StandardSafetyAnalysis Report prohibited. The DCVs will have horizontal steel plates located above the openings that will prevent any material falling in the dr)well from directly entering the vertical leg of the DCVs. This arrangement is similar to that used with the Afark II connecting vent pipes. Vertically oriented trash rack construction will be installed around the periphery of the horizontal steel plate to intercept debris. The trash rack design shall allow for adequate flow from the drywell to wetwell. In order for debris to enter 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 drywell to the wetwell.
In the Perry incident, the insulation material acted as a sepia to filter suspended solids from the suppression pool water. The Mark I, II, 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 settle out at the bottom of the pool undl they are stirred up and resuspended in the water following some event (SRV lifting). In contrast, the ABWR liner of the suppression poolis fabricated from stainless steel which significantly lowers the amount of corrosion products which can accumulate at the bottom of the pool.
Since die debris in the Perry incident was created by roughing filters on the containment cooling units a comparison of the key design features of the ABWR is necessary. In the Mark III design more than 1/2 of the containment cooling units are                        (
effectively located in the wetwell airspace. For the ABWR there are no cooling fan units
                                                                                                                              }
in the wetwell air space. Funhermore the design of the ABWR Dr>well Cooling Systems 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. TheA SPCU is described in Section 9.5.9 and shown in Figure 9.5.1 cf 1.; /M"1 SSMhe                                l l            SPCU is designed to provide a continuous cleanup flow of 250 m3 /h. This flow rate is                        j sufficiendy large to effectively maintain the suppression pool water at the required purity.The SPCU system is 'ntended 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.                                                          .]
                                                                                                              %,        p The ABWR will at a mimimum, size the ECCS suction strainers in accordance with Reg. D l '
Guide 1.82 for all breaks required to be considered. Breaks invohing the Main Steam i Lines are expected to determine the strainer size per Reg. Guide 1.82. To address the uncertainty regarding the potential non-consewatism associated with the head loss
                        ~_
6C-2                                          Containment Debris Protection for ECCS Strainers - Arnendment 34
 
.=,    . . .                                                                                l l
                '6 C.5      Strainer Sizing Annlysis 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, RIIR with three loops has six screen regions. The IIPCF      l with two loops has four screen regions, and the RCIC has two screen regions. The characteristic dimension given for the screens in the results below indicates a surface area consisting of a circle with a diameter of the dimension plus a cylinder with a diameter and length of the dimension.
Ily 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 volume of debris on the screen, the velocity of fluid      ;
passing through the screen (runout flow used), and the screen area.        1 The debris created pressure drop was equated to the diffe ence between the pump available NPSIl and the required NPSil. The available NPSil takes into account the pipeline losses to the pump suction, which are the unplugged screen, the pipe, the valves and          i fittings, and the suppression pool water level determined by the          'l draw down calculated as applicable for a main steam line break              i scenario. A summary of the applicable quantitative information            I input is provided in Table 6C-1, and a summary of the analysis              l results is provided in Table 6C-2.
i,
 
tJ '  .
l N SERT        A                                  -
G C. 3    S.G 1, 8 '1      Iw. g v ov ew hi All ECCS f !trainers will at a minimum be sized to conform with the guidance provided in Reg Guide 1.82(Rev.) for the most severe of all postulated breaks.
Y The following clarifying assumptions will also be applied and will take precedence:
(1)      The debris generation model will utilize right angle cones acting in both 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; (3)      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 pool is 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.
J
 
a;,      ,.'
                                                                                          .i
.3 Table 6C 1 Dehris    Annlysis    input Parameters Estimated debris created ' by a main steam line break'    2.'6 m3.
RIIR runout flow (Figure 5.4-11, note 13)                1130 m3 /h 3
IIPCF runout flow (Table 6.3-8)                          890 m /h  ~
RCIC controlled constant flow (Table 5.4-2)              182 m3 /h Debris on RilR screen region, 3 RIIR loops operating    ' 0.433 m3.
Debris on llPCF screen region-                            0.367 m3.
Debris on RCIC screen region                              0.097 m3.
RIIR required NPSil (Table 6.3-9)                        2.4 m IIPCF required NPSII (Table 6.3-8)                        2.2 m                '
RCIC required NPSil (Table 5.4-2)                        7.3 m RllR pipe and fittings hydraulic losses                  0.59 m IIPCF pipe and fittings hydraulic losses                0.51 m RCIC pipe and fittings hydraulic losses                ' 0.36 m Suppression pool static head above pump suction          5.3 m Table 6C-2
                                      - Results. of Annlysis RilR screen region area / characteristic dimension        4.74 m2 / 1.1 m llPCF screen region area / characteristic dimension      1.21 m2 / 0,55m RCIC screen region area / characteristic dimension        0.24 m2 / 0.25.m-Total ECCS screen region area                            33.76 - m 2'          ,
                                                                                          'l I
o
                                                                                          .i
                                                                                      .}}

Revision as of 22:47, 30 March 2020

Forwards Submittal Supporting Accelerated ABWR Schedule Re Suppression Pool Strainers
ML20065J701
Person / Time
Site: 05200001
Issue date: 04/14/1994
From: Fox J
GENERAL ELECTRIC CO.
To: Poslusny C
Office of Nuclear Reactor Regulation
References
IEB-93-002, IEB-93-2, NUDOCS 9404180385
Download: ML20065J701 (8)
v • d • e


Text

Retrieved from "https://kanterella.com/w/index.php?title=ML20065J701&oldid=2725083"