ML20198S139

Forwards Open Items Associated W/External Reactor Vessel Cooling SER for AP600

ML20198S139
Person / Time
Site:	05200003
Issue date:	12/08/1997
From:	Joseph Sebrosky NRC (Affiliation Not Assigned)
To:	Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
References
NUDOCS 9801260083
Download: ML20198S139 (4)

Text

~

• '/

_,C.

?^

Tv

~

y 4

' December 8d1997

^

4 V

a v

+' y a

? Mr. Nicholas J. Liparulo, Manager.

[

' Nuclear Safety and Regulatory Analysis :,

T 4"

s.

Nuclear and Advanced Technology Division -

T Westinghouse Electric Corporation >

P.O. Box 3551 _

LPittsburgh, PA 15230-

SUBJECT:

. OPEN ITEMS ASSOCIATED WITH EXTERNAL REACTOR VESSEL COOLING -

SAFETY EVALUATION REPORT (SER) FOR THE AP600

=

Dear Mr. uparulo:

4 The Containment Systems and Severe Accident Branch has provided an SER for their review

associated with extemal reactor vessel cooling for the AP600. Howecor, the SER contained -

1some open item.s.' These open items have been extracted from the SER and can be found in the'-

. enclosure to this letterc

':LYou havi requested that potilons of the information submitted in the June 1992, application for.

g idesign certification be exempt from mandatory public disclosure.L While the staff has not completed its review of your request in accordance with the requirements of 10 CFR 2.790, that d

E portum of the submitted information is being withheld from public disclosure pending the staff's

final determination. The staff concludes that these follow on questions do not contain those portions of the information for which exemption is sought. However, the staff will withhold this-11etter from public disclosure for 30 calendar daya from the date of this letter to allow Westing-house the opportunity to verify the' staff's conclusions. If, after that time, you do not request that '

i all or portions of the information in the enclosures be withheld from public disclosure in accor-dance with 10 CFR 2.790, this letter'will be placed in tM Nuclear Regulatory Commission Public Document Room, w

if you have any questions regarding this matter, you may contact me at (301) 4151132.'

Sincerely, original sign'ed by:

Joseph M. Sebrosky, Project Manager Standardization Project Directorate

. Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003 J;

'i qr 7+f t.

i m

m, 1

Enclosure:

LAs stated

.f f I~

+

' cc w/ encl: L See next page s

DISTRIBUTION:

p

, e @ @ *eana

S.e next page '

..u %.,<.,:o; D

~~

$ DOC MENT.NAME: A:SCSB_.IVR.RAI

. e ;,.

W To receive a copy of this' document, ladicate in the box: "C" = Cop without attachment / enclosure < "E" = Copy'

' Lwith rattachment/ enclosure "N" = No copy

-r-OFFICE PM:PDST:DRPM l1 DCSB:DSSA cl-D:PDST:DRPNI l l-

~

NAME:

JMSebrosky seM RPalla ffd4 TRQua( #.

DATE 12/e,/97 -

U-12/9 /97-12/6197 //4 ~

~

v

. OFFICIAL RECORD COPY-

~

em Mr. Nicholas J. Liparulo -

Docket No.52-003 Westinghouse Electric Corporation AP600 cc:

Mr. B. A. McIntyre Ms. Cindy L. Haag Advanced Plant Safety & Licensirig Advanced Plant Safety & Licensing Westinghouse Electric Corporation Westinghouse Electric Corporation Energy Systems Business Unit Energy Systems Busir.ess Unit P.O. Box 355 Box 355 Pittsburgh, PA 15230 Pittsburgh, PA 15230 z

Enclosure to be distributed to the following addressees after the result of the proprietary evaluation is received from Westinghouse:

Mr. Russ Bell Ms. Lynn Connor Senior Project Manager, Programs DOC-Search Associates Nuclear Energy Institute Post Office Box 34 1776 i Street, NW Cabin John, MD 20818 Suite 300 Washington, DC 20006 3706 Mr. Robert H. Buchholi GE Nuclear Energy Dr. Craig D. Sawyer, Manager 175 Curtner Avenue, MC-781 Advanced Reacer Programs San Jose, CA 95125 GE Nuclear EnerJ<.

175 Curtner Avenut, MC-754 Mr. Sterling Franks Sar. Jose, CA 95125 U.S. Department of Energy NE-50 Barton Z. Cowan. Esq.

19901 Germantown Road Eckert Seamans Cherin & Mellott Germantown, MD 20874 600 Grant Street 42nd Floor Pittsburgh, PA 15219 Mr, Charles Thompson, Nuclear Engineer 1

AP600 Certification Mr. Frank A. Ross NE 50 U.S. Department of Energy, NE-42 19901 Germantown Road Office of LWR Safety and Technology Germantown, MD 20874 19901 Germantown Road Germantown, MD 20874 Mr. Ed Rodwell, Manager PWR Design Certification Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303

. ~.

_. -..._~..._ -..

1 3

~

~

DISTRIBUTION: Letter to Mr. Nicholas J.- Lioarulo. dated: - Decomher 8_

1997 l

f *DochetFNsJEnclosure to be held for 30 days l

• PUBLIC ~

PDST R/F -

TQuay

- TKenyon :

+ WHuffman-

'JSebrosky _

DScaletti

. JNWilson.

' ACRS (ii) -

WDean,0 5 E23 r

' JMoore,0-15 B18

- RPalla,0-8 H7

'JKudrick,0-8 H7

~ MSnodderly,0-8 H7 i

4 a

-1 i

i J'

j i

1

)

g d.

'}

~

r 4

.p'_'

e

.J

)

4 Open Iteins Associated with Extemal Reactor Vessel Cooling for the AP600 Open Nem 720.454F WEC did not submit en evaluation of the potential for debris blockage of the ERVC flow path, or -

specify a functional requirement to assure that the~ cages and other p?rts of the coolant flow path are not subject to debris blockage. Based on information provided by WEC on related topics, the

)

staff considers bicekage of the ERVC flow path to be a potential conear,1. Specifically, in response to RAI 480.1079 WEC indicated that the RCS blowdown during a LOCA will tend to carry debris created by the accident into the reactor cavity, and that during the flood-up time,-

materials will settle to the floors of the loop compartments or the reactor cavity, in response to '

RAI 480.148, WEC ncted that the entrance pathway into the RPV insulation is elevated and the water level at the time of debris relocation is several meters above the bottom of the insulation so floating or submerged debris cannot be ingested into the insulation flowpath. However, the high flow rates through the system (possibly as high as 10,000 gpm according to estimates provided by Westinghouse during an August 17,1997, meeting), in oor$ unction with the relatively small RPV insulation entrance and its proximity to the rescior cavity floor, could result in re-4 suspension and transport of debris to the entrance of the insulation system. Also, in response to j

RAI 480.148, WEC indicated that there are no screens to plug and the water flow paths in the Insulation are large. This response is not consistent with the conceptual insulation design information provided in Chapter 39 of the PRA and in Appendix K of the ROAAM report, which indicates that the insulation system includes an unspecified number of buoyant stainless steel

. balls enclosed within perforated screen like cages. Details regarding the flow area and mesh size of the cages have not been provided. Thus, the staff is unable to conclude that the ERVC 4

flow path is not subject to plugging. The staff concludes that the potential for debris blockage of the ERVC flow path needs to be evaluated by WEC, and that a functional requirement needs to be provided to assure that the cages and other parts of the coulant flow path are not subject to 4

debria blockage. This is an Open item.

[

Open item 720.455F 1

WEC indicated that a structural analysis was performed for the conceptual design of the RPV insulation system and that the results of the evaluation show that the desigr was able to meet each of the defined functional requirements. Thus, a design that meets the functional requirements is feasible. However, the RPV insulation design descYption or a complete set of functional requirements are not currently included in the SSAR or ITAAC. In view of the reliance on ERVC to meet the Commission's large release frequency and containment performance goals, the design description and all functional requirements for the RPV insulation should be added to the SSAR, and important criteria associated with the insulation design should be incorporated into the ITAAC, including information related to the necessary clearances / flow areas, and the check valves and steam vent dampers. Altematively WEC can adopt a Design Acceptance Criteria (DAC) approach, in which case, the complete set of design criteria or functional design requirements, including pressure loading and deflection criteria, nceds to be

^

incorporated in the SSAR and in system ITAAC. In either case, the system should be included as a risk-significant SSC in the reliability assurance program, and reliability / availability controls and goals should be provided to assure that operability of the system and moving parts is maintained. - This is an Open item, i:

Enclosure A

W'-

Q.

99 d'

Fu 4

_