ML20063K032

Forwards Revised Ssar Markup Addressing Open Item F6.2.1.9-1 Re Suppression Pool Strainers

ML20063K032
Person / Time
Site:	05200001
Issue date:	02/14/1994
From:	Fox J GENERAL ELECTRIC CO.
To:	Poslusny C Office of Nuclear Reactor Regulation
References
NUDOCS 9402280121
Download: ML20063K032 (3)

Text

..

s: '( )  ;

• '~

.;_ GE Nuclear Energy

"~~~- ,, ,;a m ,e uno,

!/S [ f !s1 A.rr:or, ,5an .icst: CA Ti!Je5 l

l i

February 14,1994 Docket No.52-001 i 1

i j

Chet Poslusny, Senior Project Manager  :

Standardization Project Directorate  ;

Associate Directorate for Advanced Reactors .

and License Renewal i Office of the Nuclear Reactor Regulation l

Subject:

Submittal Supporting Accelerated ABWR Schedule -

Response to Open Item F6.2.1.9-1 (Resubmittal)

Dear Chet:

Enclosed is a revised SSAR markup addressing the subject open item pertaining to supression pool strainers.

Please provide a copy of this transmittal to John Monninger.

Sincerel >,

l n J Fox Advanced Reactor Programs l cc: Alan Beard GE)

Norman Fletcher DOE)

Joe Quirk GE Bill Taft GE ry sewan 22001a - ( \

9402280121 940214 PDR ADOCK 05200001 PDR _ __. _ _ . _ _ _ _ _ _ - - . _ .

.. . ~ . ... _ .

- I l

• - 23A6100 Rxv. 3 l

, g l

ABWR. ' s m a n a s a n y A selys b aer a t i

prohibited. The DCVs will have horizontal steel plates located above the openings that  ;

will prevent any material falling in the drywell from directly entering the vertical leg of j the DCVs. This arrangement is similar to that used with the Mark II connecting vent i 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. l 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 III 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 until they are stirred up and resuspended in the water following some event (SRV lifting). In contrast, tha ABWRliner 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.

'i Since the debris in the Peny incident was created by roughing filters on the I,

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. Furthermore the design of the ABWR Drywell 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. The ,

SPCU is described in Section 9.5.9 and shown in Figure 9.5.1 of the ABWR SSAR. The 3 I l SPCU is designed to provide a continuous cleanup flow of 250 m /hr. This flow rate is sufficiently large to effectively maintain the suppression pool water at the required purity. The SPCU system is intended for continuous opemtion and the suction pressure i 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 ofdebris were to enter the suppression pool and cause the strainer to become plugged resulting in a low suction pressure alann.

(N SERT A >

The F.CC puT.p n. qn p: ! min:= fr i .""*? "" -m i: nquke r.:nt of l- Rg :oq CA : =. The suction strainers at Perry did not meet the current regulatory requirements. The ABWR ECCS suction strainers will utilize a T 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 6C 2 Containment Debris Protection for ECCS Strainers - Amendment 33  ;

IN SERT A The ABWR will at a minimum, size the ECCS suction strainers in accordance with Reg Guide 1.82 for all breaks requued to be considered. Breaks involving the Main Steam Lines are expected to determine the strainer size per Reg Guide 1.82. To address the uncertainty reganhag the potential non conservatism associated with the lead loss calculations performed for strainer sizing the following additional requirement will be met.:

For breaks other than those involving the main and RCIC steam systems, the RHR suction strainers will have a consnucted area at least 3 times the basic strainer surface area obtained from Reg Guide 1.82, as required for the specific break under consideration.