ML20064G362
| ML20064G362 | |
| Person / Time | |
|---|---|
| Site: | 05200001 |
| Issue date: | 03/10/1994 |
| From: | Fox J GENERAL ELECTRIC CO. |
| To: | Poslusny C Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 9403160151 | |
| Download: ML20064G362 (5) | |
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...-.a4,=w..~ni-Ilb (u"..f! J'WV!T;16 Y}!) b4? [N.?tlh 5 March 10,1994 Docket No.52-001 I"
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 Suaporting Accelerated ABWR Schedule -
Materials Se:ection Portion of Open Item Fl.9-1 l
Dear Chet:
Eneiosed is a revised respone to the materials selection portion of Open Item F1.9-1.
j Please provide a copy of this transmittal to Roger Pedersen.
Sincere,
J k Fox l
Advanced Reactor Programs j
cc:
Alan Beard GE) llal Careway GE) i Norman Fletcher DOE)
Joe Quirk GE) 4 140017
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23A6100 Rsv 1 ABWR st:nd:rd s:f:ty An: lysis Rip:tt i
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Stellite is used for hard facing of components which must be extremely wear resistant.
Use of high cobalt alloys such as Stellite is restricted to those applicatmns where no satisfactory alternative materialis available. An alternative material (Colmonoy) has been used for some hard facings in the core area.
anc} M o4 enol SMe.cdt on 12.3.1.1 Equipment Desi nffor Maintaining Exposure ALARA
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D C S 59 Thi's subsection describes sptcific components, as well as system design features, that aid in maintaining the exposure of plant personnel during system operation and maintenance AIARA. Equipment layout to provide ALARA exposures of plant personnel is discussed in Subsection 12.3.1.2.
(1) Pumps Pumps located in radiation areas are designed to minimize the time required for maintenance. Quick change cartridge-type seals on pumps, and pumps with back pullout features that permit removal of the pump impeller or mechanical seals without disassembly of attached piping, are employed to minimize exposure dme during pump maintenance. The configuration of piping about pumps is designed to provide sufIicient space for eflicient pump maintenance. Provisions are made for flushing and in certain cases chemically cleaning pumps prior to maintenance. Pump casing drains provide a means for draining pumps to the sumps prior to disassembly, thus reducing the exposure.of personnel and decreasing the potential for contamination.
Where two or more pumps conveying highly radioactive fluids are required for operational reasons to be located adjacent to each other, shielding is provided between the pumps to maintain exposure levels ALARA. An example of this situadon is the CUW circulation pumps. Pumps adjacent to other highly radioactive equipment are also shielded to reduce the maintenance exposure, for example,in the Radwaste System.
Whenever possible, operation of the pumps and associated vahing for radioactive systems is accomplished remotely. Pump control instrumentation is located outside high radiation areas, and motor or pneumatic-operated valves and valve extension stems are employed to allow operation from outside these areas.
(2) Instrumentation Instruments are located in low radiation areas such as shielded valve galleries, corridors, or control rooms, whenever possible. Shielded valve galleries l
provided for this purpose include those for the CUW, FPCC, and Radwaste (cleanup phase separator, spent resin tank, and waste evaporator) Systems.
Instruments required to be located in high radiation areas due to operational 12.3 2 Radiation Protection Design Features - Amendment 31
23A6100 R:v.1
.ABWR St:nd:rd S1ty An: lysis Rep:rt (8) SGTS. Filters The SGTS filter is located in a separate shielded cubicle and is separated by a shield wall from the exhaust fans to reduce the radiation exposure of personnel during maintenance. The dampers located in the cubicles are remotely-operated, thus requiring no access to the cubicle during operation.
A pneumatic transfer system is employed to remove the radioactive charcoal from the filter, requiring entry into the shielded cubicle only during the connection of the hoses to the SGTS filter unit.
-9 I r4 SEB.T A 12.3.1.2 Plant Design for Maintaining Exposure (ALARA)
This subsection describes features of equipment layout and design which are employed to maintain personnel exposures ALARA (1) Penetrations g
Penetrations through shield walls are avoided whenever possible to reduce the number of streaming paths provided by these penetrations. Whenever penetrations are required through shield walls, however, they are located to minimize the impact on surrounding areas. Penetrations are located so that the radiation source cannot "see" through the penetration. When this is not possible, or to provide an added order of reduction, penetrations are located to exit far above floor levelin open corridors cr in other relatively inaccessible areas. Penetrations which are offset through a shield wall are frequendy employed for electrical penetmtions to reduce the streaming of radiation through these penetrations.
Where permitted, the annular region between pipe and penetration sleeves, as well as electrical penetrations, are filled with shielding material to reduce the streaming area presented by these penetrations. The shielding materials used in these applications include a lead-loaded silicone foam, with a density comparable to concrete, and a boron-loaded refractory-type material for applications requiring neutron as well as gamma shielding. There are certain penetrations where these two approaches are not feasible or are not sufficiendy effective. In those cases, a shielded enclosure around the penetration as it exits in the shield wall, with a 90 degree bend of the process pipe as it exits the penetration,is employed.
(2) Sample Stations Sample stations in the plant provide for the routine surveillance of reactor water quality. These sample stations are located in low radiation areas to reduce the exposure to operating personnel. Flushing provisions are included using demineralized water, and pipe drains to plant sumps are provided to 12.3-5 Radiation Protection Design features - Amendment 31
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s 23A8100 R2v.1 ABWR Sts:d:rd S:f:ty An: lysis Report 12.3.7.3 Requirements of 10CFR70.24 COL applicants will provide information showing that their plant meets the requirements of 10CFR70.24 or request an exemption from this 10CFR 70.24 requirement (Subsection 12.3.4.3).
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12.3.8 References 12.3 1 N. M. SchaelTer, ReactorShieldingfor Nuclear Enginem, TID-25951, U.S. Atomic A
Energy Commission (1973).
12.3-2 J. H. Hubbell, Photon Cross Sections, Attenuation Coefficients, andEnergy Absorption Coefficientsfrom 10 KeVto 100 GeV, NSRDS-NBS20, U.S. Department af Commerce, August 1969.
j 12.13 RadiologicalHealth Handbook, U.S. Department of Health, Education, and Welfare, Revised Edition, January 1970, 12.3-4 Reactor Handbook, Volume III, Part B, E.P. Blizzard, U.S. Atomic Energy Commission (1962).
J 12.3-5 Lederer, Hollander, and Perlman, Table ofIsotopes, Sixth Edition (1968).
12.S6 M.A. Capo, Polynomial Approximation of Gamma Ray Buildup Factorsfor a Point Isotropic Source, APEX-510, November 1958.
.i 12.S7 Reactor Physics Constants, Second Edition, ANL-5800, U.S. Atomic Energy Commission, July 1963.
12.18 ENDF/B III and ENDF/B-IV Cross Section Libraries, Brookhaven National j
Laboratory.
12.3-9 PDS-31 Cross Section Library, Oak Ridge National l2boratory.
12.S10 DLC-7, ENDF/B Photo Interar. tion Library.
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mom + s n s w] W 7 e s u r4 12.3-29 Radistron Protection Design features - Amendment 31
4 INSERT A 12.3.1.1.2 Material Selection In the ABWR design maintaining radiation exposure ALARA has been considered in the material selection of systems and components exposed to reactor coolant. For example, radiation exposure potential has been reduced appreciably through the removal or l
reduction of cobalt from many components as compared to the current BWR fleet. Much of the cobalt is removed from contact with reactor coolant by eliminating Stellite where practical and reducing cobalt in the core stainless steel components. The cost of using very low cobalt materials through out the plant is prohibitive with the cost of 0.02 wt percent cobalt stainless steel approximately 8 times that of 0.05 wt percent stainless steel.
Therefore, the ABWR design has taken a graded approach by using the most expensive though lowest cobalt bearing materials in the most radiologically significant areas with increasing cobalt content in less sensitive areas. The ABWR standards for cobalt are: 0,02 wt percent for those items in the core; 0.03 wt percent for those items in the vessel internals; and 0.05 wt percent for all other components Also, with the current materials, there are no proven substitutes for Stellite for many hard surface applications such as MSIV seats. Current efTorts by the nuclear and metallurgical industry indicate that in the future, practical alternatives to Stellite maybe feasible and are being researched.
The COL applicant shall address material selection of systems and components exposed to reactor coolant to maintain radiation exposures ALARA. See Subsection 12.3.7.4 for COL license information requirements.
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