ML20248A024
| ML20248A024 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 05/27/1998 |
| From: | Kenyon T NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9805290271 | |
| Download: ML20248A024 (3) | |
Text
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UNITED STATES g
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30ESH001 May 27, 1998 pfp 9 Mr. Nicholas J. Liparulo, Manager Nuclear Safety and Regulatory Activities
' Nuclear and Advanced Technology Division Westinghouse Electric Company J
P.O. Box 355
. Pittsburgh, PA 15230
Dear Mr. Liparulo:
SUBJECT:
SECOND INTERIM LETTER FROM THE ADVISORY COMMITTEE ON REACTOR l
SAFEGUARDS (ACRS) ON THE AP600 DESIGN Enclosed is the second interim letter from the ACRS on the safety aspects of the AP600 design dated April 9,1998, in which the Committee offered comments and recommendations regarding concems raised during the March 31, and April 1,1998 meeting of the Subcommittee on J
Advanced Reactor Designs and the April 2 through 4,1998 meeting of the ACRS Full Commit-tee. In that letter, the Committee raises three concems on the AP600 design. The following additional information or action is requested from Westinghouse to assist the staff with address-ing the Committee's concems.
- 1. Site Characteristics in its April 9,1998 letter, the ACRS recommended that the staff should
... ensure that the calculational methodologies used by the Combined License (COL) applicant to derive X/Q not mask the effects of any unique site meteorology-cel characteristics related to topology, geographical location, directed wind flows during specific times of the day, or any peculiar atmospheric inversion characteris-tics.
In Section 2.3.6 of the AP600 Standard Safety Analyses Report (SSAR), Westinghouse states that Combined License applicants referencing the AP600 certified design will address the site specific short term and long-term X/Q values, in Sections 2.3.4 and 2.3.5 of the Standard j
Review Plan (SRP), the staff states that the applicants should provide (1) meteorological data
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which represent annual cycles of houriy values of wind speed, wind direction, and atmospheric stability, and (2) topographical characteristics in the vicinity of the site for restrictions of horizontal l
and/or vertical plum spread, channeling or other changes in airflow trajectories, and other unusual conditions affecting atmospheric transport and diffusion between the source and receptors. The SRP identifies examples of unusual conditions, such as narrow, deep valleys; b3 land-ses (lake) breeze regimes; and low-level subsidence inversion of temperature.
i The staff concludes that it is appropriate for Westinghouse to augment the COL Action items in 1
the AP600 SSAR Sections 2.3.6.4 and 2.3.6.5 to state that the COL applicant should consider l
topographical characteristics in the vicinity of the site for restrictions of norizontal and/or vertical l
plum spread, channeling or other changes in airflow trajectories, and other unusual conditions affecting atmospheric transport and diffusion between the source and receptors as described in SRP Sections 2.3.4 and 2.3.5.
9805290271 980527
'" W NRC FfLE CENTER COPY
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i Mr. Nicholas J. Liparulo May 27, 1998
- 2. Security in its April 9,1998 letter, the ACRS expressed concem that reduction of access portals to the vital areas of the AP600 could have safety implications, especially during plant upset conditions, emergencies (such as fires), and implementation of the Emergency Plan, because of the security restrictions on access to equipment. The Committee recommended that the staff evaluate the impact of the security design on the safety aspects of the plant.
Discussions with your staff indicate that Westinghouse is evaluating the access capability to certain vital areas, and that it is developing a response to address this concem. As discussed with your staff, we understand that Westinghouse will be prepared to discuss its proposed resolution at the June 17 and 18,1998 ACRS subcommittee meeting.
- 3. Accident Analyses in its April 9,1998 letter, the ACRS recommended that the justification for granting credit for aerosol removal from the AP600 containment atmosphere by diffusiophoresis and thermophoresis following an accident be documented. Based on the discussions with your staff on May 21,1998, the staff believes that it has sufficient information available to respond to this question, and no further information is requested at this time.
If you have any questions regarding this matter, you can contact me at (301) 415-1120.
Sincerely, original signed by:
Theodore R. Quay Thomas J. Kenyon, Project Manager Standardization Project Directorate Division of Reactor Program Management Office of Nuclear Reactor Regulation Docket No.52-003
Enclosure:
As stated cc w/ encl: See next page DISTRIBUTION:
Docket File PDST R/F JRoe DMatthews PUBLIC TQuay TKenyon WHuffman DScaletti JNWilson JSebrosky MDusaniwskyj ACRS (11)
JMoore,0-15 B18 REmch,0-10 D4 JLee,0-10 D4 MSnodderly,0-8 H7 RPalla,0-8 H7 RAlbert,0-11 E22 DOCUMENT NAME: A:\\ACRS.LTR To receive a copy of this document, indicate in the box: "C" = Copy without attachment / enclosure "E" = Copy with attachment / enclosure "N" = No copy OFFICE PM:PDST:DRPM l BC:PERB:DRPM F D:PDST:DRPM l c l
NAME TJKenyon:sg TTW CLMiller (M TRQuay %
DATE 05/27/98 4"
05/ 7J/98 05/11/98 OFFICIAL RECORD COPY
- y Mr. Nicholas J. Liparulo Docket No.52-003 Westinghouse Electric Corporation AP600 cc:
Mr. B. A. McIntyre Mr. Russ Bell Advanced Plant Safety & Licensing Senior Project Manager, Programs Westinghouse Electric Corporation Nuclear Energy Institute Energy Systems Business Unit 1776 l Street, NW P.O. Box 355 Suite 300 -
Pittsburgh, PA 15230 Washington, DC 20006-3706 Ms. Cindy L. Haag Ms. Lynn Connor Advanced Plant Safety & Licensing Doc-Search Associates Westinghouse Electric Corporation Post Office Box 34 Energy Systems Business Unit Cabin John, MD 20818 Box 355 -
Pittsburgh, PA 15230 Dr. Craig D. Sawyer, Manager Advanced Reactor Programs Mr. Sterling Franks GE Nuclear Energy U.S. Department of Energy 175 Curtner Avenue, MC-754 NE 50 San Jose, CA 95125 19901 Germantown Road Germantown, MD 20874 Mr. Robert H. Buchholz GE Nuclear Energy Mr. Frank A. Ross '
175 Curtner Avenue, MC-781 I
U.S. Department of Energy, NE-42 San Jose, CA 95125 Office of LWR Safety and Technology 19901 Germantown Road Barton Z. Cowan, Esq.
Germantown, MD 20874 Eckert Seamans Cherin & Mellott 600 Grant Street 42nd Floor Mr. Charles Thompson, Nuclear Engineer Pittsburgh, PA 15219 AP600 Certification
)
NE-50 Mr. Ed Rodwell, Manager j
19901 Germantown Road PWR Design Certification Germantown, MD 20874 Electnc Power Research Institute f
3412 Hillview Avenue Mr. Robert Maiers, P.E.
Palo Alto, CA 94303 Pennsylvania Department of Environmental Protection Bureau of Radiation Protection Rachel Carson State Office Building
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P.O. Box 8469 Harrisburg, PA 17105-8469 i
1 I
8 UNITED STATES 8
NUCLEAR REGULATORY COMMISSION n
E ADVISORY COMMITTEE ON REACTOR SAFEGUARDS r#
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April 9,1998 i
Mr. L. Joseph Callan Executive Director for Operations U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Dear Mr. Callan:
SUBJECT:
THE SAFETY ASPECTS OF THE WESTINGHOUSE ELECTRIC COMPANY I
APPLICATION FOR CERTIFICATION OF THE AP600 PLANT DESIGN -
INTERIM LETTER 2 During the 451st meeting of the Advisory Committee on Reactor Safeguards, April 2-4,1998, we reviewed various chapters of the AP600 Standard Safety Analysis Report (SSAR) and associated chapters of the draft Final Safety Evaluation Report (FSER). Our Subcommittee on Advanced Reactor Designs reviewed these chapters on March 31-April 1,1998. During these reviews, we had the benefit of dis. ussions with representatives of the NRC staff and the Westinghouse Electric Company and of the documents referenced.
We reviewed the following SSAR and associated draft FSER chapters:
Chapter 2 - Site Characteristics Chapter 9 - Auxiliary Systems, including Appendix 9A-Fire Protection Analysis Chapter 10 - Steam and Power Conversion System Chapter 12 - Radiation Protection Chapter 13 - Section 13.6, Industrial Security Chapter 15 - Accident Analyses l
Based on our review of the above SSAR and associated draft FSER chapters, we offer the following comments and recommendations.
Chapter 2 - Site Charactenstics in order to meet the 10 CFR 50.34, " Contents of applications; technical information," siting dose criteria, site-specific short-term and long-term atmospheric dispersion factors X Q should meet
/
the AP600 design acceptance values. These acceptance values place limits on the outcomes of site-specific atmospheric dispersion calculations and define bounds on the meteorological characteristics of acceptable sites.
The NRC staff should ensure that the calculational methodologies used by the Combined License applicant to derive x/Q not mask the effects of any unique site meteorological EDO -- G980226
- /03Y1 DA Enclosure
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characteristics related to topology, geographical location, directed wind flows during specific times of the day, or any peculiar atmospheric inverson characteristics.
Chanter 9 - Auxiliary Systems. Includina Armandix 9A - Fire Protection Analysis We have not completed our review of the fire protection system and the fire protection analysis.
We plan to provide our views at a later date.
Chaoter 13 - Section 13.6 Industrial Security The design simplicity of the AP600 permits a security design that eliminates the need for some of the features described in 10 CFR 73.55,
- Requirements for physical protection of licensed activities in nuclear power reactors against radiological sabotage." The number of access portals to the vital areas is reduced to a minimum to accommodate personnel and material flow.
This approach enhances the security design and requires less manpower for responding to attempted intrusions.
Although the proposed security design meets the applicable regulations, it appears to make routine operations and maintenance activities more difficult. Restrictions such as personnel searches will cause delay for personnel when entering areas of the plant containing equipment, which must be surveilled, operated, and mainteined. These restrictions could have safety implications, especially during plant upset conditions, emergencies such as fires, and implementation of the station Emergency Plan.
We recommend that the staff evaluate the impact of the security design on the safety aspects of the plant. The additional time required to perform personnel searches might well increase the expected response times of the fire brigade and operators attempting to mitigate safety significant events. We expect to review the results of this evaluation.
Chanter 15 - Accident Analvses in assessing the acceptability of the AP600 design in meeting the regulatory dose criteria associated with design-basis accidents (DBAs), Westinghouse has proposed taking credit for natural aerosol removal processes that occur in the containment. These processes include agglomeration, gravitational sedimentation, diffusional plateout, diffusiophoresis, and thermophoresis. In the past, the design-basis source term was considered to account implicitly for these and other natural aerosol removal processes in both the reactor coolant system and in the containment. The new source term released to the containment implicitly accounts for only the effects of aerosol removal processes in the reactor coolant system. Radionuclides deposition in the containment must now be calculated explicitly.
The processes of agglomeration, sedimentation, and diffusion are present at all times for all accident sequences and containment designs (and are not significantly dependent on thermal-hydraulic conditions). Thus, these specific processes can be accounted for explicitly without specifying the thermal-hydraulic conditions. The processes of diffusiophoresis and thermophoresis, on the other hand, depend on the synchronization of the thermal-hydraulic
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' processes (steam condensation rates and development of thermal gradients across boundary layers) with the associated source-term concentrations in the containment. For current operating plants, the relative timing of source term release and thermal-hydraulic phenomena have been shown to be dependent on both plant design and event sequence. It is not clear what thermal-hydraulic conditions should be associated with the DBA source term, which is an amalgamation of source terms associated with a range of severe accident sequences.
Westinghouse has chosen the thermal-hydraulic conditions of a specific sequence (i.e., a direct vessel injection line break) for use with the DBA source term to take credit for difiusiophoresis and thermophoresis. The DBA concept is intended to ensure that the containment design results in an acceptable risk for all accident sequences. It is not clear that the thermal-hydraulic conditions of the selected sequence is consistent with the desired generality of the source term.
Specifying the thermal-hydraulic conditions associated with a specific sequence for use with the new source term appears to constitute an unprecedented interpretation of the design-basis concept. We recommend that the justification for granting credit for aerosol removal due to diffuslophoresis and thermophoresis be documented. Furthermore, the staff should make it clear that such credit is not intended to be generic for other plant designs.
Dr. Dana A. Powers did not participate in the Committee's deliberations regarding the DBA source term.
Sincerely, R.L.Seale Chairman
References:
1.
Letter dated February 19,1998, from R. L. Seale, Chairman, ACRS, to L. Joseph Callan, Executive Director for Operations, NRC,
Subject:
Interim Letter on the Safety Aspects of the Westinghouse Electric Company Application for Certification of the AP600 Plant Design.
2.
U.S. Department of Energy report prepared by Westinghouse Electric Corporation.
- AP600 Standard Safety Analysis Report," updated through Revision 20 dated February 6,1998.
3.
Memorandum dated March 9,1998, from Jack W. Roe, Office of Nuclear Reactor Regulation, NRC, to John T. Larkins, Executive Director, ACRS,
Subject:
Transmittal of Advanced Copy of Chapter 12 of the AP600 Final Safety Evaluation Report (FSER)
(Predecisional Draft).
3
-4 4.
Memorandum dated March 17,1998, from Jack W. Roe, Office of Nuclear Reactor Regulation, NRC, to John T. Larkins, Executive Director, ACRS,
Subject:
Transmittal of Advanced Copy of Chapter 2 of the AP600 Final Safety Evaluation Report (FSER)
(Predecisional Draft).
l 5.
Memorandum dated March 17,1998, from Jack W. Roe, Office of Nuclear Reactor Regulation, NRC, to John T. Larkins, Executive Director, ACRS,
Subject:
Transmittal of Advanced Copy of Chapter 9 of the AP600 Final Safety Evaluation Report (FSER)
(Predecisional Draft).
6.
Memorandum dated March 17,1998, from Jack W. Roe, Office of Nuclear Reactor Regulation, NRC, to John T. Larkins, Executive Director, ACRS,
Subject:
Transmittal of Advanced Copy of Chapter 10 of the AP600 Final Safety Evaluation Report (FSER)
(Predecisional Draft).
7.
Memorandum dated March 17,1998, from Jack W. Roe, Office of Nuclear Reactor Regulation, NRC, to John T. Larkins, Executive Director, ACRS,
Subject:
Transmittal of.
Advanced Copy of Chapter 15 of the AP600 Final Safety Evaluation Report (FSER)
(Predecisional Draft).
8.
Memorandum dated March 24,1998, from Jack W. Roe, Office of Nuclear Reactor Regulation, NRC, to John T. Larkins, Executive Director, ACRS,
Subject:
Transmittal of Advanced Copy of Section 9.5.1 of the AP600 Final Safety Evaluation Report (FSER)
(Predecisional Draft).
9.
Memorandum dated March 23,1998, from Jack W. Roe, Office o' Nuclear Reactor Regulation, NRC, to John T. Larkins, Executive Director, ACRS,
Subject:
Transmittal of Advanced Copy of Section 13.6 of the AP600 Final Safety Evaluation Report (FSER)
(Predecisional Draft).
10.
Westinghouse AP600 Security Design Vulnerability Analysis Report, GS-ASR-002, Revision 2, dated February 3,1998 (Safeguards Information).
11.
Westinghouse AP600 Security Design Report, GS-ASR-001, Revision 5, dated February 3,1998 (Safeguards information).
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