ML20034H719

Requests Response to Encl Request for Addl Info on Passive Containment Cooling Sys Performance by 930409

ML20034H719
Person / Time
Site:	05200004
Issue date:	03/12/1993
From:	Malloy M Office of Nuclear Reactor Regulation
To:	Marriott P GENERAL ELECTRIC CO.
References
NUDOCS 9303190321
Download: ML20034H719 (4)

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Docket'No.52-004 March 12, 1993 Mr. Patrick W. Marriott, Manager Licensing & Consulting Services GE Nuclear Energy

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175 Curtner Avenue San Jose, California 95125

SUBJECT:

TRANSMITTAL OF REQUESTS FOR ADDITIONAL INFORMATION (RAI) FOR THE SIMPLIFIED BOILING WATER REACTOR (SBWR) DESIGN - PASSIVE CONTAINMENT COOLING SYSTEM (PCCS) PERFORMANCE Our January 28, 1993, letter to you forwarded a number of round zero RAls.

Omitted from that transmittal were RAls on PCCS performance which are provided in the enclosure. GE's response to these RAls by April 9, 1993, will greatly facilitate current work (PCCS modeling for severe accident calculations) by the.0ffice of Nuclear Regulatory Research in support of the SBWR design certification review.

As stated in our earlier letter, the round zero RAls are not intended to complete the RAI stage of the SBWR review. However, GE responses to these initial staff concerns will further the overall review process.

Should you have any questions regarding this request, please contact me at (301) 504-1178 or Mr. Son Ninh at (301) 504-1125.

This requirement affects nine or fewer respondents and; therefore, is not subject to Office of Management and Budget review under P.L.96-511.

Sincerely, f0NNaMaNO"y PkectManager 1

Standardization Project Directorate Associate Directorate for Advanced Reactors e

and License Renewal i

Office of Nuclear Reactor Regulation -

Enclosure:

Round Zero RAIs on PCCS Performance cc w/ enclosure:

See next page c

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Mr. Patrick W. Marriott

. Docket No.52-004 General Electric Company.

cc:

Mr. Laurence S. Gifford GE Nuclear Energy 12300 Twinbrook Parkway Suite 315 Rockville, Maryland 20852 Director, Criteria & Standards Division 1

Office of Radiation Programs U. S. Environmental Protection Agency 401 M Street, S.W.

Washington, D.C.

20460 Mr. Sterling Franks U. S. Department of Energy NE-42 Washington, D.C.

20585 Mr. Jeffrey C. Baechler GE Nuclear Energy 175 Curtner Avenue, MC-782

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San Jose, California 95125 Mr. Frank A. Ross Program Manager, ALWR Office of LWR Safety & Technology U.S. Department of Energy NE-42 19901 Germantown Road Germantown, Maryland 20874 D

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ADDITIONAL SIMPLIFIED BOILING WATER REACTOR (SBWR) ROUND ZERD REQUESTS FOR ADDITIONAL INFORMATION (RAls)

Questions Regarding Passive Containment Cooling System (PCCS)

Performance - In the following questions, the term " capacity" is l

intended to denote both the heat removal rate (watts) and the steam condensation rate (kg/s). The questions are structured to support a modeling approach by which a basic capacity is deter-

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mined each calculational time step depending upon the isolation condenser (IC) system or PCCS pool temperature. This basic capacity would.then be operated upon by correction factors to i

reflect the effects of flow through the PCCS vent line and the presence of noncondensable gas.

It is recognized that other approaches are feasible and that the detailed information available at GE may be more appropriate to an alternate approach.

If this is the case, then provision of the requested information in a different form (such as tables) would be appropriate.

RAI Number Question RES.I What is the basic PCCS capacity (per unit) produced by steam' condensation. in the tubes (no flow from drywell to pressure suppression pool via the PCCS vent line, no noncondensable gas in the drywell atmosphere, and IC 'or PCCS pool temperature at its initial value)? What is the drywell' pressure associated with this basic capacity?

RES.2 How does the basic PCCS capacity defined in Question RES.I decrease as IC/PCCS pool temperature increases over the range from its initial temperature to saturation temperature?

j RES.3 How does the basic PCCS capacity defined in Question RES.I increase as the drywell-to-suppression chamber differential

i pressure increases from 1.05 psid (initiating flow through the vent line) to 2.30 psid (initiating flow through the upper row of horizontal vents)?

RES.4 How does the basic PCCS capacity defined in Question RES.I decrease as the noncondensable gas fraction at the PCCS inlet increases?

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What are the expected sensitivities (if any) to the composition'of' the noncondensable gas?

4 Enclosure

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'ADDITIANAL SIMPLIFIED BOILING WATER REACTOR.-(SBWR) ROUND ZERO RAlsl(cont'd.)

j Questions Regarding Important Heat Sinks - The following questions concern certain important heat sinks in.the' drywell;and pressure suppression chamber airspace. These are either water-cooled steel structures or_ thin fins for which the thicknesses cannot be found.

i in the ' standardized safety analysis report (SSAR)..;It is believed-that the effects of these heat sinks would significantly affect -

the drywell-to-suppression chamber pressure differential. (and,

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therefore, the PCCS performance) over the.long term under postu-

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lated severe accident-conditions.

RAI Number Question RES.6 What is the thickness of the gravity-driven cooling; system pool walls at the interface with the drywell atmosphere?. - Per..SSAR 1

Section 3.8.3.1, these are "made of. stainless steel ' plates.or..

carbon steel plates lined with stainless steel. cladding and backed'..

s up with vertical' and horizontal steel structural framing system."

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RES.7 What is the thickness-of the-(water-cooled) drywell head?.

RES.8 What is the thickness-of the fins in the' pressure suppression

.i chamber airspace? Per SSAR Section 3.8.3.1, these:" project down-l 1.0 m (3'-3") below the 0.6 m (2'-0") thick floor....The radial'.

plate, with a flange plate at the bottom,; forms = thetsupport beam to'the floor system." Figure 21.1.2-2 Sheet 9-(Reactor Building, 1

Plan at Elevation 16000) shows that there are 24 of these~ fins.

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