RC-18-0080, Virgil C. Summer Nuclear Station, Unit 1, Updated Final Safety Analysis Report, Chapter 12.0, Radiation Protection
Text
12.1-1 Reformatted M ay 2018 NOTE 12.0 Section 12.0 is being retained for historical purposes only.
12.0 RADIATION PROTECTION Paragraph 20.1(c) of 10 CFR 20, states that licensees should, in addition to complying with the limits set forth in that part, make every reasonable effort to maintain radiation exposures as far below the limits as practicable. The as low as practicable philosophy was followed in designing the Virgil C. Summer Nuclear Station.
This philosophy is reflected in the design by layout recommendations for pipes carrying radioactive fluids, equipment design, handling, and maintenance features. For example, pipe runs carrying radioactive fluid are arranged to minimize potential crud traps. Lines which transport spent resin are arranged with five diameter bends and continuous sloping. Piping vent and drain locations are minimized to reduce possible leakage paths and crud traps. Where possible, vents and drains are consolidated so that one vent and one drain serve several lines. Components that may require periodic maintenance are shielded from components most likely to be high radiation sources. Shielding is provided for fixed sample vessels associated with equipment stream pumps. Canned pumps are used in the liquid waste processing system (LWPS) to minimize potential leakage of radioactive fluids. Pumps requiring local start
-stop or jog switches are placed in shielded cubicles. Control switches for such pumps are located outside the cubicles. Filters have lifting bails located on the heads to facilitate cartrid ge assembly removal and disposable cartridges for ease of changing. Demineralizers in the LWPS are considered to be potentially radioactive and are located inside individually shielded cubicles. Tanks containing radioactive waste are located in watertight compartments to contain the tank contents in the event of leakage. Heat exchangers incorporate design features that minimize exposure time during maintenance. Valves are located so that operation and maintenance can be performed from standard service equipment. Valves which normally carry radioactive fluid have leakoffs. Equipment and/or components that may require servicing are located or designed to be movable to the lowest practicable radiation field. Penetrations through shielding walls are designed to minimize exposure. Radiation sources and normally occupied areas are separated. Pipes or ducts containing potentially highly radioactive fluids either do not pass through occupied areas or are shielded by shield slabs. Provisions are made for flushing equipment prior to maintenance where practicable. Ventilation systems are designed for easy access and service to minimize doses during maintenance, decontamination, filter changes, etc. Remote handling equipment is provided wherever practicable. Movable shields and means for their utilization are available for use as practicable. Where practicable, shielding is provided between radiation sources and areas requiring normal or routine access. As a result of operating experience, permanent removable shielding has been incorporated to minimize radiation exposure for operations and maintenance personnel in local areas such as for parts of the Residual Heat Removal and Safety Injection piping.
02-01 12.1-2 Reformatted M ay 2018 General guidance on the radiation protection aspects of the balance of plant design (BOP) is provided to engineers and designers by the appropriate discipline project engineer. Specific guidelines concerning BOP design are provided to the individual engineers whose specialties are radiation protection. These guidelines are based upon accumulated indepth design experience available to the architect
-engineer from previously completed nuclear projects, as well as the experience acquired from frequent visits to operating nuclear plants. In addition to the design experience of the architect-engineer, conceptual shielding design guidelines are also provided from References [3], [8], and [9] (see Section 12.1.7). BOP design is reviewed by both the architect
-engineer and SCE&G personnel who are competent in radiation protection. The review by the architect
-engineer is accomplished through internal circulation of drawings and other design documents. When these documents contain design information that affects the radiation exposures to which plant workers will be subject ed, they are reviewed by a group of specialists competent in radiation protection. This review results in the elimination or mitigation, to the extent practicable, of design features that would result in unnecessary radiation exposure. The individuals wh o have performed such reviews for the Virgil C. Summer Nuclear Station have the following position titles: Supervising Engineer, Project Engineer, Nuclear Engineer, Staff Health Physicist. Their qualifications include either a B. S. or M. S. degree in nuclear engineering, health physics or a related science, and six to ten years of experience related to radiation protection.
Westinghouse is responsive to the ALARA requirements of Regulatory Guide 8.8 and has devoted considerable effort via design and technology to minimize occupational radiation exposures due to equipment/systems/components within Westinghouse scope. Although Westinghouse does not charge the design engineers whose expertise lies in fluid dynamics, thermodynamics, etc. with radiation protection functions, Westinghouse does employ system analysis engineers, competent in the area of health physics and radiation protection, to work with those engineers in their disciplines of component or system design. Together, these personnel participate in the design review process in a systematic manner.
Following the review of design by the architect
-engineer, and NSSS vendor, the design Engineering and Operations groups.
Comments or changes required as a result of these reviews are incorporated or resolved prior to the issuance of the documents for construction. This review is accomplished by various engineers cognizant of radiation protection considerations assigned to the Nuclear Engineering Group, by the Staff Health Physicist, and by Station Health Physics. Qualifications of these reviewing personnel include appropriate education/degrees and experience ranging from 5 to 10 years.
12.1-3 Reformatted M ay 2018 Specific examples of BOP areas reviewed during the design review process and changes made in the BOP as a result of the design review include:
- 1. Radiation Shielding
- a. A permali shield for the push
-pull rod for the out
-of-core detector at the 180° reactor vessel position was added to prevent neutron streaming to an area outside the secondary shield.
- b. The gap between the reactor building and the fuel handling building was shielded to prevent streaming when spent fuel elements are transferred from the reactor building to the fuel handlin g building.
- c. The wall separating the mixed bed demineralizers in the chemical and volume control system (CVCS) was increased in thickness to lower the potential dose from the adjacent demineralizer.
- d. The sample sink was relocated to make it possible to put the sample lines and the sample vessels in a shielded chase.
- 2. Facility and Equipment Design
- a. The original design of the solid radwaste area, which did not include provisions for separation of high and low level waste, was modified to provide separate storage areas.
- b. The decontamination area in the hot machine shop was increased and additional equipment (a turbolator and additional ultrasonic sinks) was added to provide more capability for equipment and tool decontamination.
- c. The design previously included a provision for processing blowdown with minimal radioactivity through the cycle makeup demineralizers. This provision was deleted to preclude the possibility of a significant radiation source occurring in an unlimited access area.
- 3. Location of Instrumentation Two (2) monitors were relocated to lower radiation areas. Radiation monitor RM
-L1 was moved from a CVCS piping area to a lower radiation area. Radiation Monitor RM-L6 was moved from a valve gallery to an operator access corri dor. 02-01 12.1-4 Reformatted M ay 2018 Examples of design features developed by the NSSS vendor and other features in WCAP-8872, "Design, Inspection, Operation and Maintenance Aspects of the Westinghouse NSSS to Maintain Occupational Exposures as Low as Reasonably Achievable, edited by R. J. Lutz, April, 1977." These radiation protection design considerations have resulted in satisfying 10 CFR 20. Thus, the basic intent of Regulatory Guide 8.8 concerning as low as reasonably achievable (ALARA) is satisfied. It is the policy of the management of SCE&G that future design and construction also be accomplished in such a manner as to maintain occupational radiation exposures ALARA.
12.1 RADIATION SHIELDING Radiation protection of plant operating personnel is accomplished by the use of adequate shielding against radiation. This radiation shielding is provided principally by concrete walls, floors, and ceilings, the thickness of which was determined by the need for access to the area, the type of radiation sources present, and structural requirements. Therefore, where structural strength is the controlling criteria, the radiation shielding provided is in excess of requirements.
NOTE 12.1.1 Section 12.1.1 is being retained for historical purposes only.
12.1.1 DESIGN OBJECTIVES The primary objective of the radiation protection systems, shielding design, and administrative controls is protection of operating personnel and the general public from potential radiation sources in the reactor, radwaste systems, and other auxiliary systems, including associated equipment and piping.
During normal operation, including anticipated operational occurrences, the design objectives for the radiation shielding are as follows:
- 1. To restrict the quarterly and annual doses to plant operating personnel and visiting radiation workers to within the limits set forth in 10 CFR 20. These limits are given in Table 12.1
-1. Maximum whole body exposure rates are generally less than 100 mrem/hr, except in the case of certain maintenance, inspection, and refueling functions. The maximum dose rate in each instance is determined by the 10 CFR 20 quarterly restriction, by the required exposure time and by the previous and anticipated subsequent doses during the quarter.
RN 00-058 12.1-5 Reformatted M ay 2018 2. To limit onsite whole body doses to nonoccupational workers and site visitors to 500 mrem/yr, with a maximum whole body dose during any given seven consecutive day period of 100 mrem. These personnel are not permitted in area s where whole body exposure rates are greater than 2.0 mrem/hr. 3. To ensure that the integrated offsite dose is within the limits specified by 10 CFR 20.
- 4. To protect certain components from excessive radiation damage or activation.
In the unlikely event of an accident, the radiation shielding design objectives are as follows: 1. To satisfy the requirements of 10 CFR 50, Appendix A, Criterion 19, i.e., to provide adequate radiation protection for operating personnel following a reactor accident such that the accident may be terminated without excessive radiation exposure to the operators or the general public.
- 2. To limit offsite doses from both contained and released radioactivity to within the limitations set forth in 10 CFR 50.67. The above shielding objectives served as an upper limit during design of the radiation shielding. The philosophy followed during design and construction of the plant has been to give extensive consideration to the shielding design to assure that radiation exposures to personnel are kept as low as is reasonably achievable (ALARA). This philosophy has resulted in a shielding design that results in occupational and general public exposures being well within the design objectives previously listed. During the operational phase of plant life, this policy of maintaining radiation exposures at a minimum will be continued.
12.1.2 DESIGN DESCRIPTION Scaled layouts and cross sections of the Reactor Building and surrounding shield buildings and of the Auxiliary, Control, and Fuel Handling Buildings are provided by Figures 12.1-1 through 12.1
-20. While these figures do show specific layout of equipment, the purpose of presenting these figures is to show specific areas in the plant which have been zoned in accordance with maximum design radiation levels and occupancy requirements. These figures will be revised only when the boundaries or designations of the radiation zones change and will not be revised to show equipment relocations, deletions, additions, etc. Figure 1.2-1 shows the total plant layout within the site boundary, as well as identifying any outside storage areas and railroad spur or siding locations.
RN 12-034 12.1-6 Reformatted M ay 2018 12.1.2.1 Plant Shielding Description Specific areas in the plant have been zoned in accordance with maximum design radiation levels and occupancy requirements. The occupancy requirements have been based on the general access requirements (as defined by an analysis of the operation of the plant and from information obtained from operating facilities) and access requirements for other operations such as maintenance, refueling, instrument calibration, and similar reoccurring activities. An explanation of each of the five zones and the maximum dose rates anticipated are given below:
Zone Occupancy Dose Rate (mrem/hr)
I Un controlled. No restrictions on occupancy expected.
< 1.0 II Controlled, Unlimited access, 40 hrs/week
< 2.5 III Controlled. Limited access, 6 to 40 hrs/week.
< 15.0 IV Limited access for short periods, 1 to 6 hrs/week.
< 100.0 V Controlled, high radiation area, occupancy averages less than one hr/week.
> 100.0 The radiation shielding is designed to attenuate direct and scattered radiation according to the dose limits required by this zoning.
The locations of these radiation zones throughout the plant are depicted in the layouts shown by Figures 12.1-1 through 12.1
-20. An equipment list is presented as Figure 1.2-28a. Figures 12.1-1 through 12.1
-9 show this radiation zoning for the plant during normal operation, while Figures 12.1-10 through 12.1-18 depict this zoning for zoning of the Control Building during normal operating and shutdown periods. The radiation sources used in determining these radiation levels are defined in Section 12.1.3 and were calculated assuming fuel cladding failures of one percent. The thickness of radiation shielding in various parts of the plant is presented in Table 12.1-1a. Plant radiation shielding is divided into six categories: primary, secondary, Reactor Building, Control Room, fuel transfer, and Auxiliary Building shielding. Each of these categories is discussed below:
- 1. Primary Shield The primary shield is a concrete structure surrounding the reactor pressure vessel. It is of varied thickness and has inspection openings (above the reactor
-to-coolant pi pe nozzles) and penetration ports adjacent to the core for excore neutron detectors.
12.1-7 Reformatted M ay 2018 The excore neutron detector push rods penetrate the primary shield at the height of the core. Where these penetrations are not inside the secondary shield, one foot thic k permali (densified beechwood laminate) shield covers are provided to preclude any neutron streaming from these penetrations.
The inspection openings above the reactor
-to-coolant pipe nozzles remain open during operation. They are closed during shutdown for refueling. The design of the reactor cavity and control rod missile shield is such that a direct exposure to plant personnel from these inspection openings or from the annular gap between the reactor vessel and primary shield is not possible. However, the scattering of neutron and gamma radiation from the Reactor Building dome will result in dose rates that range from 1 mrem/hr to 100 mrem/hr at the operating floor level. Measured dose rates in operating plants support this conclusion. Exposure of workers to these dose rates will be minimized since access to the operating floor during power operation is under strict administrative control. The three basic paths by which neutron and gamma radiation may stream out of the primary shield are indicated by Figure 12.1-21, with the basic locations involved as follows: a. Primary piping penetrations.
- b. Excore neutron detector instrumentation push rods.
- c. Vertical streaming of neutrons along the pressure vessel wall.
Primary piping penetrations do not contribute an appreciable amount to the dose rate in any accessible area since the penetrations are only open to the inside of the secondary compartments which are inaccessible at all times during power operation.
Neutron detector push rods penetrate the primary shield in an area which is not circumscribed by the secondary shield and neutrons of energy less than 1.0 MEV stream in iron; therefore, the COHORT
-II Monte Carlo computer code with a mono
-directional point source directed into the inner end of the push rod was utilized to calculate a neutron removal cross Section for this particular geometry. Neutron shield covers were designed to cover the areas where the push rods exit the primary shield. The neutron dose rate outside these shield covers is estimated to be less than 50 mrem/hr. It is well known that neutrons emanating from the core scatter up and out of the gap between the pressure vessel and the concrete primary shield, whereupon they are free to scatter to the operating elevation inside containment. The magnitude of the neutron dose rate on the operating elevation from this neutron source is strongly dependent upon the size of the gap between the pressure vessel flange and the primary shield. The gap width between the pressure vessel flange and the primary shield is only 7.25 inches. Therefore, it may be anticipated that the neutron dose rate on the operating elevation will be rather low.
12.1-8 Reformatted M ay 2018 Additionally, Monte Carlo calculations have been performed utilizing the COHORT
-II computer code. The main feature of the geometry of the pressure vessel, primary shield, gap, nozzles, reactor cavity, and containment were incorporated. The source was conservatively assumed to be isotropic and located in the gap on the surface of the pressure vessel over the core height. Neutrons were biased in direction (going up the gap) and in energy (toward the high energy end of the spectrum). Point fluxes and resultant dose rates were obtained on the operating level using this code. These calculation estimates indicate that the neutron dose rate will be less than 100 mrem/hr on the operating level.
Primary shielding includes the following:
- a. The elements inside the reactor pressure vessel, including the core baffle, core barrel, thermal shield, and water annuli.
- b. The reactor vessel wall.
- c. The concrete structure surrounding the reactor vessel. This structure extends from 3/4" and, at a reduced thickness except across the refueling canal, from th 3/4" elevation -8-1/4", while the upper, reduced thickness portion of the shield has a thickness o f 4 feet. The upper part of the primary concrete shielding is completed by the walls of the refueling minimum thickness of 3 feet. The primary shield as a whole or in part serves to: (1) Attenuate the neutron flux sufficiently to prevent excessive radiation damage to the reactor vessel.
(2) Reduce the heat flux from neutron and gamma radiation at the reactor vessel outer surface such that any cooling necessary to avoid high temperatures and possible dehydration in the surrounding concrete is an easier task.
(3) Attenuate neutron and gamma fluxes to prevent excessive radiation damage and activation of plant components and structures.
(4) Reduce, in conjunction with the secondary shield, the radiation escaping the reactor vessel sufficiently to allow limited access to certain areas of the Reactor Building during normal full power operation.
12.1-9 Reformatted M ay 2018 (5) Reduce the radiation escaping the reactor vessel sufficiently to permit access inside the secondary shield, at a reasonable time after shutdown, for routine maintenance and inspection.
- 2. Secondary Shield The secondary shield is a series of concrete structures which enclose the reactor coolant loops and pumps, the pressurizer and pressurizer relief tank, the steam generators, and portions of the primary shield. These structures extend from the floor at -6". The -8" thick. The main function of the secondary shield is to reduce the dose rates from the primary coolant loops such that most areas within the Reactor Building outside the secondary shield are classified as radiation Zone IV during normal full power operation and Zone III when the plant is shut down.
- 3. Reactor Building The Reactor Building is a steel reinforced concrete structure consisting of a 4 foot thick cylindrical wall and a 3 foot thick shallow dome roof. This structure encloses the Nuclear Steam Supply System (NSSS) and serves to attenuate any radiation escaping the primary
-secondary shield complex such that the radiation level in occupied areas outside the Reactor Building permits unlimited occupancy. In addition, this structure shields operating personnel and the general public from radiation sources resulting from activity released to the Reactor Building from postulated accidents. The general shielding considerations employed in the arrangement of the Reactor Building penetrations are discussed in Section 12.1.2.2. 4. Control Room Shielding Shielding for the Control Room is designed to satisfy the requirements of General Design Criterion 19, i.e., adequate radiation shielding is provided to permit continuous occupancy of the Control Room under accident conditions described in Regulatory Guide 1.183 (see Appendix 3A) without personnel receiving radiation exposures in excess of 5 rem TEDE for the duration of the accident. The shielding that is provided for the control room is as follows:
- a. Control Building walls
- each 2 feet thick.
- b. Control Building roof
- 2 feet thick.
- c. Control Room floor
- 8 inches thick.
RN 12-034 12.1-10 Reformatted M ay 2018 d. Control Room ceiling
- 9 inches thick between column lines G and H and 2 feet thick between column lines H and H.6 (see Figure 1.2-19). This shielding is of ordinary concrete and is adequate to attenuate radiation from external sources (e.g., activity inside the Reactor Building, airborne activity external to the Control Room, and activity in areas surrounding the Control Building) to a small fraction of the 5 rem TEDE limit in accordance with Regulatory Guide 1.183. A more significant portion of the radiation dose to Control Room personnel during a design basis accident is due to airborne activity within the Control Room. This subject is discussed in Chapter
- 15. Figures 12.1-19 and 12.1
-20 present a layout and section of the Control Room.
- 5. Fuel Transfer Shielding During fuel transfer operations, the refueling canal and the region above the reactor vessel are filled with borated water to an transfer canal and spent fuel pool in the Fuel Handling Building is also at elevation for the spent fuel as it is removed from the core, transferred through the refueling canal and transfer tubes, stored in the spent fuel pool, and, after a decay period, loaded into a shipping cask. This water and concrete also provide shielding from activated control rod clusters and reactor internals which are removed during refueling periods. The concentration of radioactivity in the refueling water is controlled by administrative procedures and a sufficient depth of water above the fuel assembly is maintained so that the direct exposure rate at the surface of the water does not normally exceed 2.5 mrem/hr. However, certain manipulations of fuel assemblies, rod clusters, or reactor internals may produce short term exposures in excess of 2.5 mrem/hr. The fuel transfer tube is shielded to limit doses due to radiation streaming through penetrations and gaps. Lead shielding is provided in the fuel transfer tube inspection accessway inside the Reactor Building, in the gap between the refueling cavity wall and the Reactor Building liner, and in the gap between the Reactor Building and Fuel Handling Building (see Figure 12.1-22). This shielding ensures that radiation doses do not exceed 100 mrem/hr in areas adjacent to the tube during transfer of fuel inside the Reactor Building. Lead shielding was not provided on the underside of the 3 inch gap between the Reactor Building and the cantilevered top of the retaining wall adjacent to the Reactor Building. Access to this area will be limited during refueling operations by administrative control. Radiation levels are closely monitored during refueling operations to ensure that plant personnel doses are maintained well within the limits specified by 10 CFR 20.
02-01 02-01 RN 12-034 12.1-11 Reformatted M ay 2018 6. Auxiliary Building Shielding Shielding in the Auxiliary Building is designed to protect plant personnel from radiation from components and piping of the following systems during normal operation, including anticipated operational occurrences:
- a. Chemical and Volume Control System.
- b. Waste Processing Systems.
- c. Solid Waste Disposal System. d. Residual Heat Removal System.
- e. Spent Fuel Cooling System.
- f. Boron Recycle System.
- g. Sampling Systems.
- h. Nuclear Blowdown Processing System.
Auxiliary Building shielding includes concrete floors, walls, doors, covers and/or removable blocks, and local permanent shielding such as lead plates supported by steel framing. The shielding is designed to satisfy the radiation zoning requirements set forth previously.
Where practical, shielding is also provided between components to permit pla nt personnel to enter the equipment compartments under controlled conditions and perform required maintenance without shutdown or decontamination of adjacent compartments.
Additionally, shielding design considered the location of certain manways to components to provide optimum accessibility and the best possible work area to reduce exposure time during required maintenance.
For example, in the case of the recycle holdup tanks, entrance to the cubicle is from the -6") since the compartment is watertight up to a level equivalent to the maximum volume of the tank. For normal maintenance, a platform is provided around the east side of the tank. For major maintenance, such as removal of the tank diaphragm or tank cleaning, the tank will be emptied and flushed prior to the commencement of maintenance. The manway, freedom of movement into and out of the tank. The minimal increase in exposure during major maintenance to a worker walking to the manway is more than offset by the provision of the best possible work area at the manway.
12.1-12 Reformatted M ay 2018 12.1.2.2 Plant Shielding Design Criteria To ensure that doses to plant personnel are kept within the limits specified in Section 12.1.1, shield walls are erected around plant components and piping which are anticipated to contain potentially significant amounts of radioactive materials. These shield walls are constructed of ordinary concrete (density of 145 lb/ft 3) and are sized such that radiation levels are reduced to satisfy the radiation zoning requirements defined in Section 12.1.2.1. The calculational methods used to determine the thickness and other dimensions of the shield walls are discussed in Section 12.1.2.4. In cases where access to equipment enclosures is through these shield walls, shielding effectiveness is maintained through the use of labyrinth entrances. Separation of shielded components and equipment compartments, where practicable, has been utilized in efforts to limit potential exposure during plant operation. The design criterion for piping penetrations, ducts, voids, and other irregularities in the shield walls is to situate them to minimize radiation streaming from a high radiation area to low radiation areas. If the penetrations, etc., cannot be so situated, compensatory shielding (e.g., steel or lead wool, steel plates, shadow shields, etc.) are provided. Examples of use of compensatory shielding are discussed below:
- 1. Most of the Reactor Building penetrations are in compartmentalized penetration access areas which provide further shielding for those areas of the plant more frequently occupied. Location of equipment anticipated to require frequent attention has been minimized in these access areas.
- 2. elevation is provided.
- 3. A shadow shield is provided for the out of core neutron detector push rod penetrations of the primary shield.
- 4. Most of the Auxiliary Building shield wall penetrations are located close to the ceiling of the shielded penetration access areas.
When practical, piping containing radioactive material is routed through high radiation areas where accessibility is precluded. When this is not possible, such piping is routed through shielded pipe chases which serve to reduce radiation exposure rates to plant personnel when in the vicinity of this piping. Based on operating experience additional permanent, removable local shielding has been added to local areas such as around parts of the Residual Heat Removal and Safety Injection piping to reduce radiation exposure to operation and maintenance personnel.
12.1-13 Reformatted M ay 2018 Piping containing highly radioactive fluid is routed by engineering as stated in Section 12.0. Changes in the routing of such piping due to field conditions must be approved by engineering. In this manner, the same controls and considerations applied to the original pipe routing are applied to the field changes. If the changes are not acceptable from the standpoint of radiation exposure, other measures, such as additional shielding, etc., are employed.
Routing of very small piping is accomplished in the same manner as is the routing of large piping. Small, safety class piping is designed and routed by engineering, not by the field.
Equipment which contains or processes radioactive fluids is so located as to cause minimal occupational dose to plant personnel. Demineralized Water Nuclear Services supplies hose fittings located approximately every 50 feet along Reactor Building, Auxiliary Building, and Fuel Handling Building access ways for decontamination.
The components of the Excess Liquid Waste System, such as filters, demineralizers, tanks, and pumps, provide illustrative examples of equipment location. These components are located in individual shielded cubicles with labyrinthine entrances if personnel entry is required (see Figure 12.1-3). Figures 12.1-3 through 12.1
-20 illustrate the location of equipment associated with systems, such as Spent Fuel Cooling, Reactor Makeup Water, Sampling, and Solid Waste Disposal, and individual items, such as the miscellaneous waste drain tank. Color codes on these figures indicate expected dose rates in various areas and the length of time such areas may be occupied (on a weekly basis) by plant personnel.
Systems processing radioactive liquids are equipped with diaphragm type, leak proof valves to minimize spillage of radioactive materials.
Elevated door stops, concrete curbs, and floor drain systems which route a spill to the proper waste processing system are employed to minimize the spread of contamination. An effort has been made to locate instruments requiring inplace calibration in the lowest practicable radiation zones.
Provisions have been made to allow for flushing of systems that may become contaminated.
Remote handling equipment and portable shielding is available on site for use when needed.
12.1-14 Reformatted M ay 2018 12.1.2.3 Accident Shielding The accident shielding objective is to attenuate radiation exposures due to activity in the Reactor Building to a small fraction of 10 CFR 100 limits and to a level at which required access to onsite locations can be achieved. The shielding design review performed for NUREG-0578 addresses the limitations imposed by the post
-accident radiation fields on the timely recovery from an accident due to limited personnel access capability and/or safety equipment operation degradation. The results of the shielding review are presented in Appendix 12A. 12.1.2.4 Shielding Calculational Methods The sizing of the radiation shielding required to reduce the exposure rates from the sources defined in Section 12.1.3 to satisfy the radiation zoning defined in Section 12.1.2.1 is done using the computer codes SDC
[1]or QAD6G [2] and/or hand calculations. Both SDC and the hand calculations are utilized in performing basic shielding calculations involving relatively simple geometric source configurations, such as point, line, cylinder, sphere, slab, or disk. These methods employ many of the integrations and techniques found in Reference
[3]. QAD6G is a point kernel code utilized in performing shielding calculations with more generalized, complex geometric configurations.
Radiation dose rates in and around shielded labyrinth entranceways to cubicles were estimated using a simplified albedo hand calculation. The wall that is directly exposed to the radiation source was divided into scattering areas. Then, using the geometrical configuration to determine the appropriate angles, the incident dose rates on each of the scattering areas and tabulated values of concrete gamma ray albedos, an estimate of radiation dose rates at areas in and around the labyrinths can be determined. This methodology has been checked using the G3 Code [10]. Source strengths and geometric models used for equipment during the performance of shielding calculations are presented in Tables 12.1-2 through 12.1
-5. 12.1.3 SOURCE TERMS The shielding design source items are based upon the three general plant conditions of normal full power operation, shutdown, and design basis events.
12.1-15 Reformatted M ay 2018 12.1.3.1 Sources for Normal Full Power Operation Design consideration has been given to the reduction of activation product formation and buildup. For example, materials with low cobalt content are specified for primary coolant system alloys. However, the availability, durability, and economics of component materials must always be considered during material procurement. High cobalt, hard facing wear materials, such as Stellite, which come in contact with the primary coolant are used only where substitute materials cannot meet performance requirements.
The process of high flow rate/high temperature filtration is not a standard practice in Westinghouse NSSS and is not planned for Virgil C. Summer Nuclear Station.
These methods of cobalt reduction along with valve design and quantities of nickel alloys in the primary system are discussed in detail in WCAP
-8872, "Design, Inspection, Operation and Maintenance Aspects of the Westinghouse NSSS to Maintain Occupational Radiation Exposures as Low as Reasonably Achievable." To minimize exposure levels associated with valve stem leakage, packless valves are provided for those systems that normally contain radioactive fluid. These valves are designed for zero stem leakage. A metal bellows seal is used in high pressure applications; an elastomer diaphragm, in low pressure applications. For safety related diaphragm valves, a new valve design is used. This design substantially redu ces maintenance requirements since diaphragm life has been increased by a factor of five.
Several features are incorporated into the design of packed valves to reduce crud buildup and maintenance requirements. These features include positive backseats to permit inline replacement of packing, lantern ring seal leakoffs, and special, close tolerance graphoil packing in lieu of conventional packing.
The main sources of radiation during normal full power operation are the reactor core, the reactor coolant, and auxiliary systems associated with the processing or handling of reactor coolant.
12.1.3.1.1 Reactor Core The neutron fluxes at the inside surface of the primary shield concrete at the core midplane are listed in Table 12.1-6. These fluxes represent average values on the core center plane and are based upon a core axial peaking factor of 1.30. Axial variation factors for off midplane variation of neutron flux in the primary shield concrete are also listed in Table 12.1-6. The gamma fluxes at the inside surface of the primary shield concrete at the core midplane are listed in Table 12.1-7. Values of gamma fluxes above and below the core midplane can be obtained by applying the axial variation factors which are also presented in Table 12.1-7.
12.1-16 Reformatted M ay 2018 12.1.3.1.2 Reactor Coolant The main sources of activity in the reactor coolant during normal full power operation are N16 from coolant activation processes, fission products from fuel clad defects, and corrosion and activation products. All shielding has as its design basis the maximum case of clad defects in fuel rods producing 1.0 percent of core thermal power. Activity concentrations in the reactor coolant are listed in Table 11.1-6. The activities in the pressurizer steam and liquid phases are given in Table 11.1-4 and the pressurizer deposited sources in Table 12.1-8. The N16 activity of the coolant is given in Table 12.1-9 as a function of transport time in a reactor coolant loop.
The N-16 sources in Table 12.1-9 include the effects of irradiation of the coolant both in the core and reflector regions outside the core. Transit times around a coolant loop and within the reactor vessel are based on design flow rates and active flow volumes at 100% power operation. The transit times are included in Table 12.1-9. 12.1.3.1.3 Sources for Auxiliary Systems The auxiliary system equipment for which a determination of shielding sources is required consists of pumps, heat exchangers, demineralizers, filters, units of evaporator packages, liquid tanks, gas tanks, and pipes. Reactor coolant activities assumed in the development of all auxiliary system source terms are given in Table 11.1-2 and are based upon 1.0 percent failed fuel.
12.1.3.1.3.1 Chemical and Volume Control System Sources The purpose of the Chemical and Volume Control System (CVCS) is to provide continuous purification and volume control of the reactor coolant water. The major equipment items include the regenerative and letdown heat exchangers, mixed bed and cation bed demineralizers, reactor coolant filter, volume control tank, and charging pumps. The Boron Thermal Regeneration (BTR) subsystem contains the three BTR heat exchangers and the BTR demineralizers. The Seal Water subsystem for the reactor coolant pumps includes the injection and return filters and the seal water heat exchanger. The spectral source strengths in the CVCS purification letdown flow are tabulated in Table 12.1-10. The sources assume sufficient delay time from the reactor coolant loop for decay of the N16 isotope.
The radiation sources in the ion exchangers of the CVCS system are listed in Table 12.1-2. The mixed bed retains the fission product activity, both cations and anions, and the corrosion product (crud) metals. The cation bed can be used intermittently to remove lithium for pH control and to supplement the mixed bed in removing yttrium, cesium, molybdenum, and the crud metals. The Boron Thermal Regeneration beds are used to regulate the boron concentration in the reactor coolant water. They are utilized during load following operations and for removal of boron from the coolant as the nuclear fuel is depleted. These demineralizers also collect radioactive anions, such as iodine, which may have passed through the mixed bed.
12.1-17 Reformatted M ay 2018 The sources in the volume control tank are listed in Table 12.1-3. These sources correspond to a nominal tank operating level of 125 ft 3 in the liquid phase and 175 ft 3 in the vapor phase.
Before transferring the contents of the evaporator batch tank to the boric acid tank, a sample is taken which should satisfy two criteria:
- 1. A boron content of ~ 7000 ppm 2. An activity concentration of < 0.01 µc/cc If both criteria are not satisfied, the contents are recycled through the evaporator feed demineralizers. An activity concentration of < 0.01 µc/cc in the feed to the boric acid storage tanks is the basis for not shielding the tanks and associated piping.
For filters in the CVCS system, the design criteria for handling and shielding are primarily based upon operating experience and are as follows
- 1. Capability should be provided for changing filters with radiation levels of 100 R/hr at contact with the filter housing. This criterion is applicable to the following filters: seal water injection and seal water return.
- 2. Capability should be provided for changing the reactor coolant filter with radiation levels of 500 R/hr at contact with the filter housing.
- 3. The total combined exposure to personnel changing any one of the above filters should not exceed 100 mr. The exposure rates listed in Items 1 and 2, above, are considered to be maximums, with limits controlled by periodic monitoring.
The specific source strengths of the subject filters are included in Table 12.1-4. The sources for the reactor coolant filter correspond to an exposure rate of 500 R/hr at contact. The sources for the remaining filters correspond to an exposure rate of 100 R/hr at contact. The filters are assumed to be drained of process fluid and are considered to be homogeneous sources.
The radiation sources in the heat exchangers of the CVCS system are listed in Table 12.1-5. The regenerative and excess letdown heat exchangers are located in the Reactor Building. They provide the initial cooling for the reactor coolant letdown and their sources include N16 activity. The remaining CVCS heat exchangers are located in the Auxiliary Building where N16 activity is not a significant factor. The letdown heat exchanger provides second stage cooling for the reactor coolant prior to entering the demineralizers. The seal water heat exchanger cools water from several sources, including the reactor coolant discharged from the excess letdown heat exchangers. The 12.1-18 Reformatted M ay 2018 activity of these heat exchangers is identical to that listed in Table 12.1-10. The thermal regeneration heat exchangers include the moderating, chiller, and letdown reheat units. The radiation sources in this equipment are modified to account for activity removed by the demineralizers upstream of the units.
12.1.3.1.3.2 Boron Recycle System Sources The major equipment items included in the Boron Recycle System (BRS) are the recycle holdup tank and the Reactor Water Grade System Demineralizers and associated equipment, i.e., feed demineralizers and filter, condensate demineralizers and filter, and concentrates filter. Radiation sources in the various pumps are assumed to be identical to the liquid sources in the tank from which the pump takes suction.
The radiation sources in the BRS ion exchangers are listed in Table 12.1-2. The evaporator feed demineralizers are located upstream of the holdup tanks and contain resins which remove nongaseous activity from the reactor coolant directed to the holdup tanks. A decontamination factor (DF) of 10 across those beds is taken for all particulate activity. The recycle holdup tanks are each equipped with a diaphragm. Gases which flash from the reactor coolant letdown to the holdup tanks are retained under the diaphragm until approximately 500 ft 3 of gas has accumulated. The gases are then removed to the Waste Gas System. The radiation sources in the holdup tanks are based upon an assumed letdown rate of 120 gpm to a single holdup tank with 50 percent of the volatile activity flashing into the vapor phase. These sources are listed in Table 12.1-3. The recycle evaporator feed filter and condensate filter are located downstream of their respective demineralizers and serve to retain particulates and any resin fines which may escape from the demineralizers. The maximum radiation sources in these filters are listed in Table 12.1-4. The sources for the feed filter correspond to a radiation level of 100 R/hr at contact. The condensate filter sources result in levels of less than 1 R/hr at contact. The radiation sources in the concentrates filter correspond to an exposure rate of approximately 10 R/hr. 12.1.3.1.3.3 Waste Processing System Sources The radiation sources in the Waste Processing System (WPS) are tabulated in Tables 12.1-2 through 12.1
-5 and 12.1
-11. The major equipment items in the waste gas portion are the waste gas compressors, hydrogen recombiners, and gas decay tanks. The radiation sources in this equipment are based upon cold shutdown procedures during which the radioactive gases are stripped from the reactor coolant system. Since the gases are continuously recirculated, the radiation sources in the waste gas equipment are identical.
RN 02-025 RN 07-037 RN 07-037 RN 07-037 12.1-19 Reformatted M ay 2018 The Liquid Waste Processing System is considered as several subsystems, based upon intended use during normal operation.
Low activity, non
-reactor grade water is directed to the Floor Drain Laundry and Hot shower, or Excess Waste/Decon Pit Collection (ELWS) tanks. Normally this water is analyzed, then discharged. If activity levels prevent this, the water can be processed by a demineralizer/filter. The equipment items included in the subsystems are the floor drain tank and filter, laundry and hot shower tank and filter, excess waste holdup tank demineralizer and filter, decon pit collection tank demineralizer and filter, waste monitor tank demineralizer and filter, and two waste monitor tanks. The floor drain, waste monitor, and excess waste tanks provide surge capacity for the waste holdup tank during periods when abnormal volumes of liquid waste are encountered. Hence, for shielding purposes, the radiation sources in these tanks are assumed to be the same, i.e., degassed reactor coolant. Similarly, the sources in the floor drain tank filter are based on degassed reactor coolant
. The sources in the waste monitor tank demineralizer and filter are based upon circulating reactor coolant through these components.
Maximum radiation sources in demineralizers of the WPS and ELWS are presented in Table 12.1-2. Radioactive spent resins, discharged from the various demineralizers, are retained in the spent resin storage tank. Mixed bed demineralizers contain the most radioactive resin discharged to the spent resin storage tank. These sources determine the required tank shielding. The short lived activity is allowed to decay (approximately 30 days) and the resin is then directed to the drumming station for packaging. The associated equipment includes the spent resin storage tank and the resin sluice pump and filter. The resin sluice filter is shielded for radiation levels of 100 R/hr at contact.
The waste monitor tank demineralizer can be used to remove activity admitted to the waste monitor tanks.
The maximum radiation sources in the various filters of the WPS and ELWS are listed in Table 12.1-4. The waste monitor tank filter is located downstream of the demineralizer. The sources in the condensate filter result in radiation levels of approximately 1 R/hr at contact. The monitor tank filter sources produce approximately 85 R/hr at contact. The maximum radiation levels in the spent resin sluice and floor drain tank filters a re 100 R/hr at contact.
RN 03-038 RN 03-038 RN 03-038 RN 03-038 12.1-20 Reformatted M ay 2018 Radiation sources in the various pumps of the WPS and ELWS are assumed to be identical to the liquid sources in the tank from which the pump takes suction.
Sources in the laundry and hot shower tank and filter and in the waste condensate tank are negligible. Therefore, these items do not require shielding.
Sources of solid waste for the drumming station are given in Table 12.1-11. A description of the solid waste system is given in Section 11.5. 12.1.3.1.3.4 Sources for Blowdown Systems Radiation sources for equipment in the Steam Generator Blowdown and Nuclear Blowdown Processing Systems are presented in Tables 12.1-2 through 12.1
-5. The major equipment items in these systems are the steam generator blowdown heat exchangers, nuclear blowdown holdup and monitor tanks, blowdown filters, blowdown demineralizers, and the blowdown spent resin storage tank. Radiation sources are based upon one percent failed fuel and a maximum steam generator tube leakage rate of 0.1 gpm. 12.1.3.1.3.5 Sources for Spent Fuel Cooling Systems The radiation sources in the spent fuel demineralizer and filter are listed in Tables 12.1-2 and 12.1
-4, respectively. This equipment is used to maintain water clarity and remove activity released during refueling operations and the subsequent fuel cooling period. The filter sources correspond to an exposure rate of 100 R/hr at contact. The spent fuel pool skimmer is used only for cleaning the surface of the spent fuel pool water and does not require shielding.
12.1.3.2 Sources for Shutdown 12.1.3.2.1 Primary System Sources at Shutdown The core gamma sources after shutdown are used to establish radiation shielding requirements during refueling operations and during shipment of spent fuel. The sources associated with the spent fuel are based upon an average power assembly with an irradiation time of 108 seconds (3.1 years). These source strengths per unit volume of homogenized core are listed in Table 12.1-12 for various times after shutdown.
The irradiated control rod sources are used in establishing radiation shielding requirements during refueling operations and during shipment of irradiated control rods. The absorber material used in the control rods is silver
-indium-cadmium (Ag
-In-Cd). The source strengths associated with the control rods are listed in Table 12.1-13 for various times after shutdown. The values are in terms of centimeter of height of a single control rod for an irradiation period of 100,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />.
12.1-21 Reformatted M ay 2018 The Ag-In-Cd control rod sources included in Table 12.1-13 are based on an irradiation period of 100,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />. This design basis leads to conservative source term values since it is not expected that any control rod will spend a majority of its design life (15 years) in the inserted position.
The incore detector drive wire sources are used in establishing the radiation shielding requirements for the wires when the detectors are not in use and during shipment when the detectors have failed.
The incore drive wire sources are based on the assumption that the drive wire has been lodged in the core for one full year. These sources are tabulated in Table 12.1-14 and are conservative in that the drive wires will normally be inserted in the core for short periods of time during flux mapping.
The activities of steam generator primary side surfaces are used in determining access limitations in and around the steam generators at plant shutdown.
Estimated corrosion product deposited sources are given in Table 12.1-8 and 12.1
-15. The corrosion product sources are based on the methods and equations presented in the following reference:
S. Yerazunis, E. H. Alkire and R. L. Seidel, "Mechanisms of Reactor System Activation," KAPL
-M-SMS-98, May, 1959. The transport and corrosion parameters used in the calculations are selected so that the results predicted by this method reflect operating plant data. The buildup of corrosion products deposits is treated as follows:
a) Transient crud layers are assumed to exist at a nominal thickness of 50 mg/dm 2. b) Permanent crud films are assumed to build up to 90% of their maximum thickness (nominally assumed to be 50 mg/dm 2) early in the initial cycle of operation. The remaining 10% of the deposit is then assumed to build up linearly thereafter, over the operating perio
- d. 12.1.3.2.2 Auxiliary Cooling System Sources The maximum specific source strengths in the Residual Heat Removal System are listed in Table 12.1-16. The Residual Heat Removal System is placed in operation approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after the start of reactor shutdown and reduces the reactor coolant temperature to approximately 120°F within about 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> after the start of shutdown. The sources are maximum values with credit taken for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of activity decay and purification. Accident sources in the Residual Heat Removal System are considered separately in Section 12.1.3.3.
12.1-22 Reformatted M ay 2018 12.1.3.3 Sources Under Accident Conditions The sources for accident conditions are provided in Chapter 15.
12.1.4 AREA MONITORING 12.1.4.1 Design Basis The area radiation monitors are designed to detect, indicate, annunciate, and record the radiation levels monitored at selected locations inside the plant. These locations were selected on the basis of monitoring normally occupied zones critical to plant operation, monitoring occupied areas, access corridors and fuel handling areas with potential for airborne radioactivity, and having the capability to monitor the trend of Reactor Building activity following a loss of coolant accident. These monitors provide supporting data to the surveillance of plant radiation levels as recommended by ANSI N13.2
[5] and Regulatory Guide 8.2, and as required by 10 CFR 20. Area monitor instrumentation is provided to supply information and to aid in maintaining dose rates ALARA and is not considered s afety-related. Permanently installed area radiation monitors are not provided for the containment equipment access hatch area, low level waste storage area, or high level waste storage area because of the following considerations:
- 1. Portable radiation monitoring equipment will be used to survey these areas or any other potentially radioactive areas prior to access by personnel.
- 2. Access to these areas is required infrequently and will be permitted only under the supervision of health physics personnel after issuing a radiation work permit (RWP) as described in Section 12.3.2.3.7.
- 3. Although Figure 12.1-5 (sheet 2 of 2) indicates that the dose rates in the low and high level waste storage areas result in classification of these areas as Zone V, the dose rates will normally be reduced to a level less than required for Zone V classification by use, as required, of shielding.
12.1.4.2 System Description The area radiation monitors consist of eighteen fixed and one movable channel, as identified in Table 1 2.1-19. The area radiation monitoring instruments provide indication of proper plant operation by measurement of the gamma dose rate levels in selected areas of the plant. Reliable power for the instrumentation is obtained from the diesel backed, 120 volt instrument buses. The local audible and visual alarm are powered from the 120 volt buses. The movable channel is powered from a 120 volt outlet.
RN 02-025 12.1-23 Reformatted M ay 2018 Except for the movable unit, which is equipped for local recording and indication, the measured dose rate levels are indicated and recorded on the Area Radiation Monitoring System control panel located in the Control Room. Local indication is provided for each monitor except RM
-G18. Each area radiation monitor is equipped with two adjustable alarm levels (alert and high) and a channel failure and/or loss of power alarm except RM-G7. Channel RM
-G7 provides the following alarms: alert, high radiation, loss of power to the alarm module. These alarms (from the fixed monitors) are connected to an annunciator panel on the Radiation Monitoring System control panel in the control room. Each area radiation monitor, except for RM
-G17A&B, RM
-G7, and RM
-G18, is provided with a local audible and visual alarm located near the detector or local readout. The manipulator crane area monitors RM
-G17A&B, each have an audible alarm in the fuel handling area. The alarm setpoints are adjustable and are dependent upon the location of the individual monitors. In general, the alert setpoint is adjusted to a level below the high setpoint to provide warning of a change in normal plant operation conditions. The high setpoint is generally established by the zone limitations established for each area. The gamma dose rate resulting from a postulated loss of coolant accident (LOCA) is monitored by the high range Reactor Building monitors, RM-G7 and RM-G18. RM-G7 and RM-G18 are located inside the containment and are designed to meet IEEE -323-1974, IEEE -344-1975, ANSI N320
-1978. Channels RM
-G7 and RM-G18 are composed of a Victoreen model 877-1 stainless steel ion chamber detector and a Victoreen model 876A
-1, 7-decade ratemeter. Both of these channels of instrumentation meet seismic separation and 1E power source criteria and provide the appropriate display indication, record, and alarms in the Control Room. They also meet the IEEE -323 and LOCA environmental qualification requirements. Both channels have a clear view of the operating floor area of the containment as shown in Figure 1.2-6. The response of these channels to gamma (photon) radiation at 1 mev is approximately 100% and approximately 85% at 80 kev. Based on the average gamma energy anticipated after a LOCA as shown in report NUREG CR-1237, SAND 79
-2143 (January 1980), RM-G7 and RM-G18 will respond to within +8%.
Radiation Monitors RM
-G7 and RM-G18 were added to the Radiation Monitoring System to meet the requirements of NUREG
-0578, NUREG
-0737, and Regulatory Guide 1.97, Rev.
- 2. These provide a diverse means of measuring the containment for high level gamma radiation. The detectors are stainless steel gamma sensitive ion-chamber that are wall mounted inside the containment above the 463 foot floor elevation, reference Figure 1.2-6. Continuous 7
- decade analog readout is provided in the Control Room Radiation Monitoring System panel with an indication range of 1 to 10 R/hr. The detector energy response is sensitive to 60 KEV, -15% at 80 KEV and within +/- 10% from 100 KEV to 3 Mev.
The analog signals are recorded on multipoint recorders which are seismically mounted on the Radiation Monitoring System panel. High gamma dose rate or channel failure is annunciated in the Control Room.
RN 17-030 12.1-24 Reformatted M ay 2018 1E instrument power is obtained from the A and B
-train diesel backed 120 Vac. The detector and Control Room readout have been type tested for seismic qualification to meet the requirements of IEEE -323(1974). The detector and its interface cable-connector assembly have been type tested for LOCA environment to meet Regulatory Guide 1.89. Calibration of the high range containment gamma monitors i s performed during refueling and consists of verification of the readouts by a calibrated current source and by a point source verification of response of the ion
-chamber detectors in the low range (approximately 10R).
The gamma dose rate in the Reactor Building manipulator crane area, during refueling, is monitored by RM
-G17A and RM
-G17B. Either one, upon detection of high activity or loss of signal, interlock to close the purge discharge valves (Figure 11.4-1). These monitors are not required during normal operation.
Area radiation monitor electronics have a five decade logarithmic scale with a nominal measurement accuracy of +/- 25 percent of the reading. The precision is +/- 15 percent at all levels. Area radiation monitors are calibrated on a routine basis and after any maintenance work is performed on the detector by exposure to a standard radioactive source with its calibration traceable, directly or indirectly, to the National Bureau of Standards. Calibration of the high range area monitor, RM
-G7 and RM-G18 uses a calibrated electrical current source to verify the performance of the readouts. Functional verification of all area radiation monitors, except RM
-G7 and RM-G18 is achieved by use of remotely actuated check sources (isotopic or LED signal input). Functional verification of RM
-G7 and RM-G18 is achieved through use of a built
-in electronic test signal. 12.1.5 OPERATING PROCEDURES The Manager of Health Physics Services is responsible for developing the radiation protection training program, the radiation protection program and health physics procedures to ensure that exposures of all personnel are kept within the limits of 10 CFR 20 and ALARA. These procedures and programs are developed incorporating guidance contained in Regulatory Guides 8.2, 8.8, and 8.10. Plant personnel will receive radiation protection training, the depth of which will depend upon the work assignments, individual responsibilities, and the degree of radiation hazard anticipated.
Personnel whose duties entail entering controlled areas, or directing the activities of others who enter controlled areas, are required to have radiation protection training. This training qualifies personnel to implement plans and procedures, each in his area of responsibility, to maintain doses ALARA.
Administrative controls are established to assure that procedures and requirements relating to radiation protection are followed by plant personnel.
00-01 12.1-25 Reformatted M ay 2018 Radiation control procedures are established for systems that contain, collect, store, or transport radioactive liquids, gases, and solids. These procedures ensure that occupational radiation exposures are ALARA. The procedures that control radiation exposure are subject to review and approval as outlined in Section 13.5. The basic principles of time, distance, and shielding are applied during operation and maintenance to ensure that personnel exposure is within limits. The following techniques are employed:
- 1. During initial startup, neutron and gamma dose rate surveys are performed to verify the adequacy of shielding.
- 2. During normal operations dose rate, surface contamination, and airborne radioactivity surveys are performed periodically throughout the plant and areas are zoned accordingly. These surveys ensure that data is available for planning operation and maintenance activities.
- 3. Areas are conspicuously posted in accordance with 10 CFR 20.1902 as appropriate.
- 4. A radiation work permit (RWP) system is employed to ensure proper administrative control over work in restricted areas.
The RWP is designed to ensure that the radiation conditions are defined and that appropriate measures are taken to minimize the dose received by personnel. Section 12.3.1.3 explains the use of the RWP. 5. Extension tools are used when practicable to increase the distance from the radiation source to the worker.
- 6. Equipment is moved to areas of lower radiation fields for maintenance when practicable.
- 7. Portable shielding in the form of lead bricks, lead sheets, lead shot, high density concrete block, or steel plates is used as practicable.
- 8. A personnel dosimetry program, as described in Section 12.3.3, is administered by the Health Physics group to ensure compliance with 10CFR20.
Experience gained from the operation and maintenance of several nuclear plants with whom SCE&G has contact is used to provide a basis for further evaluation.
12.1.6 ESTIMATES OF EXPOSURE The estimates of exposure presented in this Section address both the peak radiation exposure rates and expected annual doses. Personnel doses are based upon the radiation zone and the anticipated occupancy requirements for that area.
RN 01-119 12.1-26 Reformatted M ay 2018 12.1.6.1 Dose Rates at Selected Inplant Locations Figures 12.1-1 through 12.1
-20 illustrate the location of the various zones throughout the plant. These zones have been established using design parameters and estimated occupancy requirements. Expected radiation levels should be only a fraction of the design values. Table 12.1-20 lists selected inplant locations and the associates design dose rate for eac h area. 12.1.6.2 Estimates of Personnel Occupancy Requirements Occupancy requirements throughout the plant, based upon operating experience and estimated SCE&G personnel requirements, are considered in the establishment of radiation zones described in Section 12.1.2.1. To estimate occupancy requirements, plant personnel were categorized into five groups according to work function. Table 12.1-21 lists the estimated size of each group and the estimated occupancy requirements for each group in Zones I, II, and III. Estimates were not made for Zones IV and V since routine occupancy is not anticipated in these zones during normal operation or during anticipated operational occurrences.
12.1.6.3 Estimates of Annual Man
-Rem Doses Annual doses to plant personnel are estimated based upon the assumption of 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> per year work time for each employee. For each zone, the lower and upper ends of the range have been evaluated in determining man
-Rem doses. It is anticipated that the general radiation levels for each zone will be equal to or less than the lower values stated for the zone although isolated higher levels will exist in certain areas within the zone.
The estimated man
-Rem doses for the various categories of plant personnel as discussed in Section 12.1.6.2 are listed in Table 12.1-21. The total annual dose for plant operation is conservatively estimated to range from 72 to 364 man
-Rems. From the years 1969 to 1974, operational data indicate that for all light water reactors the average dose was approximately 404 man
-Rem/unit/year
[6]. At Virgil C. Summer Nuclear Station the man
-Rem doses are maintained ALARA by utilizing applicable operational data and guidance available in the industry and from the government in conjunction with the Health Physics ALARA oriented program (see Section 12.3). Numerous dose assessment techniques are utilized in optimizing shielding design and in maintaining radiation doses ALARA. Regulatory guidance, such as that found in Regulatory Guide 8.8, is followed in plant design and review. Some of the specific dose assessment techniques are as follows:
12.1-27 Reformatted M ay 2018 1. Utilization of operational data:
- a. Operational radiation levels.
- b. Trends in radiation levels associated with years of operation, plant type, plant size, power levels, plant design, etc.
- c. Radiation zones as described by occupancy requirements and actual radiation levels.
- d. Location of components with respect to plant operability.
- e. Reliability of components.
- f. Adequacy of plant layout in terms of traffic patterns; space allocation, such as around radioactive components requiring maintenance and inspection; pipe routing, etc.
- g. Number of plant employees associated with different tasks and the resulting man-Rem doses.
- 2. Review equipment and instrumentation and locate in zones I and II whenever possible to minimize occupancy requirements in higher radiation zones.
- 3. Review of the plant design by a competent professional in radiation protection and by the utility radiation protection manager.
As indicated by Tab le 12.1-22 no man-Rem estimates were made for Zones IV and V. It is anticipated that entry to these zones will be primarily during plant shutdown when special maintenance will be performed. Every effort will be made to decrease the radiation dose to the maintenance personnel by utilizing temporary shielding, component decontamination, or other acceptable techniques for assuring that radiation doses are ALARA. An analysis of operational data indicates that special maintenance has contributed approximately 20 percent to the annual plant dose [6,7]. Other operations have contributed to the annual plant man
-Rem dose as follows
[6]: 1. Routine reactor operation and surveillance, 14 percent. 2. Routine maintenance, 45 percent. 3. Inservice inspection, 2.7 p ercent. 4. Waste processing, 2.5 percent. 5. Refueling, 14 percent.
12.1-28 Reformatted M ay 2018 A further estimate of the man
-Rem doses has been made by identifying specific tasks anticipated to occur at the plant. Various data from operating plants and in current publications (see References [11] through[19]) were used in identifying these tasks, manpower effort required to complete each task, and the radiation levels associated with doing the work. Tables 12.1-22a and 12.1
-22b list the tasks anticipated for normal operation and those expected during an outage. Tables 12.1-22c and 12.1
-22d provide a breakdown of personnel that will be involved with each of the tasks and the extent of their involvement. Special maintenance tasks have been analyzed although it is anticipated that these tasks will occur infrequently. When these tasks, such as steam generator maintenance, are performed the man
-Rem dose varies directly with the conditions surrounding the maintenance and the extent of the work to be performed at the time. Therefore, because of the variability of the man
-Rem dose for special maintenance, special maintenance has been excluded from the yearly personnel dose commitment (see Table 12.1-22e). Radiation doses associated with airborne radioactivity have not been analyzed in terms of tasks due to the lack of sufficient data. Conservative estimates were made using the occupancies given in Table 12.1-21. Table 12.1-22f presents the dose rates in various parts of the plant using calculated airborne contamination levels listed in Table 12.2-1. To determine the man
-Rem dose commitment from airborne activity (see Table 12.1-22g), it was assumed that the airborne radiation levels to which plant personnel will be exposed are represented by those levels for the Turbine Building (Zon e I), Auxiliary Building (Zone II) and the letdown heat exchangers (Zones III through V) listed in Table 12.1-22f. No man
-Rem doses were calculated using the specific concentrations for the Reactor Building since routine occupancy of this area during normal operation is not anticipated.
12.1.6.4 Doses at the Radiation Controlled Area Boundary The Radiation Controlled Area is located within the site boundary as defined in Figure 2.1-3. Additionally, except for unusual and unanticipated situations, the Radiation Controlled Area will not extend beyond the Protected Area fence. The only normal exceptions to this are: 1) the Radiography Vault which is operated under a separate license and 2) the storage of very low level materials such as exempt sources and other materials which present no significant radiological hazards. The Radiation Controlled Area consists of the Reactor Building, Auxiliary Building, Fuel Handling elevation), portions of the Intermediate Building and tendon access area, radioactive waste areas, hot maintenance areas, hot warehouse, and other areas designated by Health Physics for the purposes of radiation protection. Areas may be removed from the Radiation Controlled Area at the direction of Health Physics when operating conditions and radiation levels are such that control is not necessary for the purposes of radiation protection. The area outside the Radiation Controlled Area has been zoned less than 1 mrem/hr. It is expected that, under normal operating conditions and during anticipated operational occurrences, the radiation level outside the above mentioned Radiation Controlled Area will be only a fraction of this design level.
12.1-29 Reformatted M ay 2018 12.
1.7 REFERENCES
- 1. Arnold, E. D. and Maskewitz, B. F., "SDC, A Shielding
-Design Calculation Code for Fuel-Handling Facilities," ORNL
-3041, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 1966.
- 2. Malenfant, R. E., "QAD, A Series of Point
-Kernal General Purpose Shieldi ng Programs," LASL Report No. 3573, April 5, 1967.
- 3. U. S. Nuclear Regulatory Commission, "Reactor Shielding Design Manual," TID-7004, March 1956.
- 4. U. S. Nuclear Regulatory Commission, "Calculation of Distance Factors for Power and Test Reactor Sites," TID-14844, March 23, 1962.
- 5. American National Standard Institute, "Guide for Administrative Practices in Radiation Monitoring," ANSI N13.2, 1969.
- 6. Murphy, T. D. and Hinson, C. S., "Occupational Radiation Exposure at Light Water Cooled Power Reactor s 1969-1974," U. S. Nuclear Regulatory Commission, NUREG-75/032, June 1975.
- 7. Pelletier, C. A., et al., "Compilation and Analysis of Data on Occupational Radiation Exposure Experienced at Operating Nuclear Power Plants," September 1974. 8. Schaeffer, N.
M., Editor, "Reactor Shielding for Nuclear Engineers," TID
-25951, 1973. 9. Kowal, G. M., "Shielding Design Guides for Large Stationary Reactors," Gilbert Associates, Inc., unpublished, internal reports.
- 10. "G-33B, Multigroup Gamma Ray Scattering Code," NASA Lewis Research Center, Cleveland, Ohio.
- 11. Sejvar, J. "Normal Operation Radiation Levels in Pressurized Water Reactor Plants," Nuclear Technology, Vol. 36, pp. 48
-55, November 1977.
- 12. Lutz, R. J., Jr. "Design, Inspection, Operation and Maintenance Aspects of the W NSSS to Maintain Occupational Radiation Exposures as Low as Reasonably Achievable," WCAP
-8872, April 1977.
- 13. "Three Mile Island Unit 1 Cycle on Refueling Shutdown Radiation Levels," LR-76-2526-0111, July 21, 1976.
12.1-30 Reformatted M ay 2018 14. Personal communication: Wayne Crawford, Maintenance Supervisor at Carolina Power and Light Company, H. B. Robinson Steam Electric Plant, and E. E. Gutwein, Gilbert/Commonwealth, April 6, 1978.
- 15. Uhl, D. L., et. al., "Oconee Radiochemistry Survey Program Semi
-Annual Report, July-December 1974," Lynchburg Research Center Report 9047, July 1975.
- 16. Largest Nuclear Stations," paper presented at the Health Physics Society Meeting, Atlanta, Georgia, 1977.
- 17. Futrell, R. C., "The Practical Application of ALARA Principles to an Actual Refueling Shutdown," Duke Power Company, 1977.
- 18. Vance, J., Weaver C. L., Lepper, E. M., "A Preliminary Assessment of the Potential Impacts on Operating Nuclear Power Plants of a 500 mrem/yr Occupational Exposure Limit," Report to the Nuclear Regulatory Staff of the Atomic Industrial Forum, April 1978.
- 19. Verna, B. J., "Occupational Exposures
- Part 2," Nuclear News, September 1977.
REFERENCE LEGEND FOR SECTION 12.1 FIGURES PLANT RADIATION ZONE DESIGNATIONS Zone Color Code DescriptionDose Rate (mRem/hr)I Uncontrolled No restrictions on occupancy expected
< 1.0 mRem/hr II Controlled Unlimited access, 40 hrs/week
< 2.5 mRem/hr III Controlled Limited access, 6 to 40 hrs/week < 15.0 mRem/hr IV Limited access for short periods, 1 to 6 hrs/week
< 100 mRem/hr V Controlled, High Radiation Area Occupancy averages less than one
hour per week
> 100 mRem/hr Notes For Layout Drawings Showing Radiation Color Code Figures 12.1-12, 12.1-13, 12.1-17 and 12.1-18 The solid color of the cross-hatched areas represents t he radiation zone designations during a shutdown/refueling period while the RHR system is not in operation. The cross-hatched color repr esents the radiation zone designations during a shutdown/refueli ng period while the RHR system is in operation.
Figure 12.1-16 The solid color of the cross-hatched areas represents t he radiation zone designations during a shutdown/refueling period while the refueling canal and the region above the reactor vessel are flooded.
The cross-hatched color represents the radiation zone designations during a shutdown/refuelin g period while the refueling canal and the region above the reactor vessel are not flooded.
Figure 12.1-0 Amendment 02-01 May 2002
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12.2-1 Reformatted May 2018 12.2 VENTILATION 12.2.1 DESIGN OBJECTIVES The ventilation systems for various buildings and areas are designed to maintain ambient air temperatures suitable for personnel and equipment and to aid in minimizing radioactivity levels so that personnel are not exposed to airborne concentrations which exceed the limits of 10 CFR 20.
Calculated airborne radioactivity levels for various buildings during normal operation, including anticipated operational occurrences, are presented in Table 12.2-1, based upon the assumptions discussed in Sections 12.2.3 and 12.2.6. Calculated inhalation dose rates to personnel in various buildings are discussed in Sections 12.2.6.1.1, 12.2.6.1.2, and 12.2.6.1.3.
12.2.2 DESIGN DESCRIPTION Ventilation systems serving potentially radioactive areas and the Sections where detailed descriptions are presented are as follows:
- 1. Control Room Ventilation System, Section 9.4.1.2.1.
- 2. Controlled Access Area Exhaust System, Section 9.4.1.2.5.
- 3. Auxiliary and Radwaste Area Ventilation Systems, Section 9.4.2. 4. Spend Fuel Pool Area Ventilation System, Section 9.4.3. 5. Turbine Building Ventilation Systems, Section 9.4.4. 6. Reactor Building Charcoal Cleanup System, Section 9.4.8.2.4.
Air flow rates and approximate free volumes of buildings served by these ventilation systems are presented in Table 12.2-2. The ventilation system protective features concerning airborne and effluent radioactivity and shielding are described in Sections 11.4, 12.1, 12.1.4, and 12.2.4.
Figures 1.2-15 and 12.2-1 indicate the arrangement of the control room emergency charcoal filter plenum components and available service space. Figure 12.2-1 is representative of all charcoal
-HEPA filters in the plant. Test connections are provided in the duct system or housings after installation is completed.
Criteria for change of filters is dependent upon results of laboratory and field tests of filter system components. Test requirements are listed in Sections 6.5.1.4, 9.4.1.4, 9.4.2.4, 9.4.3.4, and 9.4.8.4.
RN 0 2-002 RN 02-002 12.2-2 Reformatted May 2018 Regulatory Guide 1.52 is discussed in Appendix 3A while design guidance contained in Regulatory Guide 8.8 is further described in Section 12.0. 12.2.3 SOURCE TERMS The airborne radioactivity which workers might be exposed to during normal operations have been considered as follows:
The concentration of radioactive gases in the coolant prior to reactor vessel head removal is established based on DAC considerations and containment ventilation system capabilities of the plant. The major isotope of concern is Xe
-133, since the other noble gas isotopes have either decayed away or been removed during the system degasification period. With conservative calculations, RCS activity which would result in the 10CFR20 occupational DAC in the containment atmosphere is appro ximately 0.1 µc/cc of Xe
-133. However, operating plant experience has indicated that no problem with fission gas release to the containment atmosphere was incurred when the vessel head was removed, with the coolant Xe
-133 concentration reduced to .05
µc/gm. Also, the exposure period is short so long as the containment purge is in operation during head removal.
The discharge of relief valves on lines which contain reactor coolant is piped to tanks, such as the pressurizer relief tank, volume control tank, recycle holdup tanks, reactor coolant drain tank, or waste holdup tank. Consequently, exposure of workers to airborne radioactivity from this source is precluded.
The gaseous activity released to the refueling water during the movement of spent fuel is expected to be insignificant. Fission product release from defective fuel cladding during refueling operations is a relatively slow process as compared to release during normal operation. Shutdown escape rate coefficients are several orders of magnitude below those during operation. Also, the noble gas activity inventories available for release from the defective fuel are reduced by radioactive decay during the fuel transfer operations.
Personnel entry into the Reactor Building at power will be limited to that absolutely necessary for essential operations. Appropriate radiological safety precautions will be implemented if entry into the reactor building at power is required.
The Reactor Building is normally purged prior to entry under shutdown conditions. If the shutdown is for maintenance, airborne activity is expected to be minimal. If the shutdown is for refueling, evaporation of tritiated water from the refueling cavity is expected to be the only source of airborne activity. As discussed in Secti on 11.1.4.3, airborne tritium concentrations during refueling will be low enough to allow 40 hour4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> per week access to the reactor building if the tritium concentration in the refueling water is limited to 2.5
µCi/gm. RN 01-119 RN 01-119 12.2-3 Reformatted May 2018 Airborne radioactivity is introduced into plant buildings when equipment processing or holding radioactive materials develops a leak. The assumed leakage rates into various buildings and the assumptions concerning the amount of radioactive material released from the leaked materials are presented in Sections 12.2.3.1 through 12.2.3.4. The values presented are based upon data presented in NUREG
-0017[1]. 12.2.3.1 Assumptions Used in Determining Airborne Activity in the Reactor Building
- 1. Leakage to the Reactor Building is 1 percent per day of the primary coolant noble gas inventory and 0.001 percent per day of the primary coolant halogen inventory. It is conservatively assumed that the tritium leakage rate is equivalent to the noble gas leakage rate.
- 2. Primary coolant inventory is based upon values provided in Table 11.1-5. 3. A Reactor Building purge frequency of 24 per year is assumed.
- 4. Radioactive nuclides are removed between purges by radioactive decay only.
12.2.3.2 Assumptions Used in Determining Airborne Activity in the Auxiliary Building 1. Leakage to the Auxiliary Building is 160 lb/day at primary coolant activity.
- 2. Primary coolant inventory is based upon values provided in Table 11.1-5. 3. A partition factor of 1 is assumed for noble gases and 0.0075 for halogens.
12.2.3.3 Assumptions Used in Determining Airborne Activity in the Turbine Building
- 1. Leakage to the Turbine Building atmosphere is 1700 lb/hr of steam at main steam activity. 2. Main steam activity is based upon values provided in Table 11.1-5. 3. A partition factor of 1 is assumed for both noble gases and halogens.
12.2.3.4 Assumptions Used in Determining Airborne Activity in Other Buildings All other buildings are expected to have negligible noble gas and halogen airborne activity. RN 01-111 RN 01-111 RN 01-111 RN 01-111 RN 02-002 12.2-4 Reformatted May 2018 12.2.4 AIRBORNE RADIOACTIVITY MONITORING 12.2.4.1 Design Basis The airborne radioactivity monitors are designed to detect, indicate, annunciate and record the radioactivity levels monitored at selected locations inside the plant. These monitors provide supporting data for the surveillance of plant radioactivity levels as recommended by ANSI N13.2
[2] and, Regulatory Guides 8.2 and 8.8, and as required by 10 CFR 20. Fixed continuous airborne radioactivity monitors taking particulate samples from ventilation ducts utilize isokinetic nozzles for air sampling designed according to ANSI N13.1
-1969. Lengths of sample lines are minimized to reduce particulate sample loss. Sample point locations are selected to obtain an optimum mixed air sample. Areas not covered by airborne radioactivity monitors are periodically checked with movable air samplers. The Reactor Building and normally occupied areas which are considered sources of airborne activity such as the spent fuel area and the sampling room are monitored with equipment sensitive to DAC levels. Controlled access areas which contain sources of airborne activity require Health Physics air sampling prior to work in these areas. Ventilation air flow design provides clean air for normal access corridors. These corridors are periodically monitored by portable air samplers. This monitoring instrumentation aids in maintaining airborne exposure as low as reasonably achievable (ALARA).
12.2.4.2 Airborne Radioactivity Monitors System Description The airborne monitors consist of ten fixed and three movable channels. Some of these channels are used for effluent monitoring, as discussed in Section 11.4. Ventilation ducts, local areas, and effluent paths are monitored in selected locations, as listed in Table 12.2-3, to provide assurance of proper plant operation.
Ventilation air flow in the Auxiliary Building is so arranged that the air flow path is in the direction of progressively greater potential contamination. This is accomplished by supplying clean air to the normally accessible areas, which are considered to be relatively free of airborne activity, and removing air from areas that could potentially have high levels of airborne activity. These areas are considered to be controlled areas, access to which is under strict administrative control. The air in the Auxiliary Building discharge path contains air from both clean and potentially contaminated areas. Thus, this air would not be representative of air breathed by personnel in the normally accessible areas regardless of whether samples are obtained upstream or downstream of the filters.
RN 01-119 12.2-5 Reformatted May 2018 In the Fuel Handling Building, the spent fuel area could be considered as a source of airborne activity. Since this is a normally accessible area, the local air and the exhaust air prior to filtration are monitored for airborne activity as discussed in Sections 12.2.4.2.5 and 12.2.4.2.7.
In the control complex, the sampling room could be considered as a source of airborne activity. This air is monitored for airborne activity as discussed in Section 12.2.4.2.6.
Periodic surveillance of accessible areas, in accordance with Sections 12.1.5 and 12.3.2, will be performed.
Reliable power for the fixed instrumentation is obtained from the diesel backed, 120 volt instrument buses. Associated sample pumps obtain power from the 480 volt diesel backed buses. This assures continuity of operation in the event of a loss of offsite power. Measured activity levels are indicated and recorded (except RM
-A11) on the Radiation Monitoring System control panel located in the control room. Local indication is provided for each channel. A differential pressure switch is provided on the particulate and iodine collection filter holders to cause an alarm on filter blockage. Another differential pressure switch is provided across the two filter holders (except on RMA-4) to cause an alarm on loss of flow. The loss of flow alarm for RMA
-4 originates from the flow indication device (photohelic). The movable monitors have local indication, recording, and alarms. Detectors have remotely actuated check sources to provide functional verification. In addition, each channel is calibrated routinely by exposure to a calibrated source traceable either directly or indirectly to NIST for verification against its initial calibration. Calibration of the monitors is performed following any required maintenance of the detectors. Measurements have an accuracy of +/- 25 percent of the true value. Precision is +/- 15 percent at all levels. Each ratemeter is equipped with two adjustable alarm levels (alert and high) and a channel failure/or loss of power alarm. These alarms, associated with the fixed monitors, are annunciated on the Radiation Monitoring System control panel in the control room. Channels which have interlock functions with other systems (see Figure 11.4-1) are provided with a bypass switch for use during maintenance or testing. Use of this switch is annunciated.
12.2.4.2.1 Control Room Supply Air, Channel RM
-A1 This channel monitors the particulate, iodine, and gaseous activity of air supplied to the control room. A sample of air is taken from the air supply duct through an isokinetic sampler nozzle and is drawn successively through a particulate sampler, an iodine sampler, and a gas sampler. The particulate sampler is equipped with a fixed filter which is continuously monitored by a lead shielded scintillator detector. The iodine sampler is similar to the particulate sampler except that an activated charcoal cartridge is used instead of a fixed filter. The fixed filter and the charcoal filter are designed to be removable for laboratory analysis. The sensitive volume of the gas sampler is shielded with lead and monitored by a scintillation detector. The approximate sensitivity and range of this channel are as follows: RN 02-002 RN 02-002 RN 02-002 RN 04-023 12.2-6 Reformatted May 2018 1. Particulate, 4.7 x 10-11 to 10-7 µCi/cc based upon Cs
-137. 2. Gas, 2 x 10
-6 to 2 x 10-2 µCi/cc based upon Kr
-85. 3. Iodine, 2 x 10-11 to 2 x 10-7 µCi/cc based upon I
-131. A high activity alarm from the gas channel automatically places the Control Room, Computer Room, Relay Room, and Instrument Repair Room Ventilation Systems in the recirculation mode, starts the Control Room Emergency Ventilation System, and closes the outside air dampers. The iodine and particulate channels provide high activity alarms to alert operating personnel. The high alarm setpoints are established on the basis of the requirements of the plant Technical Specifications and the sensitivity of the detection channels.
12.2.4.2.2 Reactor Building Air Sample Line, Channel RM-A2 This channel monitors the particulate, iodine, and gaseous activity level of the air inside the Reactor Building and is located inside the Auxiliary Building. Reactor Building air drawn from and returned through Reactor Building penetrations is monitored by RM
-A2. The readout of the monitor is used to detect leaks in systems containing primary coolant. Channel ranges are similar to those of Channel RM
-A1. To meet initial licensing requirements, the sensitivity of this monitor provides the capability to detect 10-MPC-hours of particulate and iodine radioactivity.
The monitor air sample and return lines are isolated (closed) upon occurrence of a containment isolation signal (Phase A). Post accident, this monitor can be used as a Reactor Building air sampling station, provided that Reactor Building pressure and temperature have been reduced sufficiently to allow opening of the sample line isolation valves. This monitor is also designed to withstand seismic conditions as recommended by Regulatory Guide 1.45. The monitor design is similar to that of RM
-A1, except that a moving particulate filter is used. An additional sample pump is also provided to allow operation when one pump is undergoing maintenance. The pumps and valves are located in a separate adjoining panel (XPN7321).
A high activity alarm from the gas channel initiates closure of the Reactor Building purge valves (see Figure 11.4-1). High alarm setpoints are based upon plant operating requirements, sensitivity, and measured normal background.
A fixed alarm setpoint is not applicable to radiation monitoring for reactor coolant leak detection. The activity of the reactor coolant and background radiation must be taken into consideration.
RN 99-067 RN 02-004 RN 03-011 RN 03-011 RN 01-119 RN 13-011 12.2-7 Reformatted May 2018 The particulate and gas channel s of radiation monitor RM-A2 will be operated with an initial setpoint of not less than twice background and may subsequently be readjusted based upon the changes in reactor coolant leakage and reactor building activity
. Typically, the adjustments are made to provide the most sensitive response without causing an excessive number of spurious alarms. The maximum setpoint will be limited to no more than twice the operational equilibrium or operability limit defined in design calculations for the monitor, whichever is l ess. 12.2.4.2.3 Main Plant Vent Exhaust, Channel RM
-A3 This channel is discussed in Section 11.4.2. It is used for detection of activity in the prefiltered discharge effluent from the Auxiliary Building main plant vent.
12.2.4.2.4 Reactor Building Purge Exhaust, Channel RM
-A4 This channel is discussed in Section 11.4.2. It is used for detection of activity in the prefiltered purge discharge effluent from the Reactor Building.
12.2.4.2.5 Fuel Handling Building Exhaust, Channel RM
-A6 This channel is used to monitor Fuel Handling Building exhaust air activity. Its function is to provide early detection of activity released. To meet initial licensing requirements, the sensitivity of this monitor provides for detection of 10
-MPC-hours of particulate, iodine, and gaseous activity. A sample of the exhaust air is taken by an isokinetic nozzle located in the exhaust duct upstream of the exhaust filters. A local audible alarm is provided. The design, range, and sensitivity of this channel are similar to thos e of RM-A1. The high level alarm setpoints are based upon the sensitivity of the detectors and are set to alarm per the plant Technical Specifications.
12.2.4.2.6 Sampling Rooms, channel RM
-A7 Channel RM
-A7 is a movable unit normally used to monitor a no n-isokinetic sample of the sampling room air for particulate, iodine, and gaseous activity. Its design, range, and sensitivity are similar to those of RM
-A1. The monitor may be used in other areas during refueling or as required by Health Physics personnel. The high level alarm setpoints are based upon the sensitivity of the detectors and are normally set to provide a local high alarm upon the occurrence of activity in excess of 10 CFR 20 limitations.
12.2.4.2.7 Spent Fuel Area, Channel RM
-A8 Channel RM
-A8 is a movable unit similar to RM
-A7. It is normally used for ambient air monitoring in the Fuel Handling Building for detection of particulate, iodine, and gaseous activity. The unit may be used in other areas at the discretion of Health Physics personnel. The alarm setpoints are based upon the sensitivity of the detectors and are normally set to provide a local high alarm upon occurrence of activity in excess of 10 CFR 20 limitations.
RN 02-004 RN 01-119 RN 13-011 12.2-8 Reformatted May 2018 12.2.4.2.8 Condenser Air Removal, Channel RM
-A9 This channel is d iscussed in Section 11.4.2. It is used for detection of activity in the effluent discharge of the Condenser Air Removal System and for detection of primary to secondary leakage.
12.2.4.2.9 Waste Gas Discharge, Channel RM
-A10 This channel is discussed in Section 11.4.2. It is used to provide backup control of the batch release of waste gas from the waste gas decay tanks.
12.2.4.2.10 Auxiliary Building Ventilation Monitor, Channel RM
-A11 Auxiliary Building ventilation duct air samples are monitored (see Figures 9.4-7 and 9.4-8) by a shielded scintillation detector for beta activity which is indicative of the presence of noble gases in the ventilation exhaust ducts. A pumping station is provided to sequentially obtain up to 12 different air samples from the Auxiliary Building ventilation ducts. Each of the 12 areas normally will be sequentially monitored at least once per hour. The activity of each sample is recorded locally. Indication and alarms are provided on the Radiation Monitoring System control panel in the control room. Should the sequential monitor alarm, operators in the control room can alert both individuals in the area and appropriate Health Physics personnel through the use of the Plant PA system. Should a high level alarm condition exist, appropriate Health Physics personnel can be dispatched to the specific area with portable sampling equipment. These samples will provide, on a timely basis, the information necessary to assess the airborne particulate and iodine radioactivity of the area. The approximate sensitivity and range of this channel are as follows: gas, 2 x 10
-6 to 2 x 10-2 µCi/cc based upon Kr
-85. Setpoints are adjusted as required by Health Physics personnel.
12.2.4.2.11 Movable Particulate Unit, Channel RM
-A12 Channel RM
-A12 is a movable, cart mounted unit provided to monitor and record particulate airborne activity in areas selected by Health Physics personnel. The unit provides a removable fixed particulate filter and a removable charcoal filter for laboratory analysis. The alarm setpoints are set as required by Health Physics personnel for the zones being monitored. Sensitivity and range of the particulate monitor are approximately 10
-11 to 10-7, referenced to Cs
-137. RN 04-023 RN 03-011 12.2-9 Reformatted May 2018 12.2.4.3 Detection of DAC Levels of Airborne Radioiodine and Particulates An analysis of the capability of the Airborne Radioactivity Monitoring System to detect DAC levels of airborne radioiodine and particulates in areas having potential for airborne contamination and which are normally accessed by personnel is presented in Sections 12.2.4.3.1 through 12.2.4.3.3.
The assumptions upon which this analysis is based are as follows:
- 1. DAC for airborne iodine is 2 x 10-8 µCi/cc. 2. DAC for airborne particulates (as cesium) is 6 x 10-8 µCi/cc. 3. Sensitivity of radiation monitor, RM
-A7, is as follows:
- a. For Cs-137, 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> sampling, 4
.7 x 10-11 µCi/cc. b. For I-131, 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> sampling, 2 x 10
-11 µCi/cc. 12.2.4.3.1 Control Building The sampling room is the area in the Control Building complex considered to have potential as a source of airborne activity. This room is sampled by a three channel radiation monitor, RM
-A7, which measures airborne particulate, iodine, and gaseous activity. It is assumed that if DAC levels of iodine and cesium activity are present in the sampling room air, the local radiation monitor, RM
-A7, will detect this activity in a sampling time which is inversely proportional to the concentration:
Monitor sensitivity Sample time Air concentration
- 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> Therefore, the sample time to detect one DAC of cesium is determined as follows:
Sample time
= = 0.38 min Assuming a high alarm setpoint at 3 times background, the time for response to one DAC of cesium would be approximately 1.1 minutes. RN 01-119 RN 01-119 RN 01-119 RN 01-119 RN 01-119 RN 01-119 RN 01-119 12.2-10 Reformatted May 2018 Similarly, the sample time to detect one DAC of iodine is determined as follows:
Sample time
= = 0.48 min Assuming a high alarm setpoint at 3 times background, the time for response to one DAC of iodine would be approximately 1
.4 minutes. 12.2.4.3.2 Fuel Handling Building
- 1. Spent Fuel Pool Floor Area Use of the local radiation monitor, RM
-A8, would provide response times similar to the estimates used for the sampling room radiation monitor, RM
-A7 (see Section 12.2.4.3.1):
Concentration Detection Time (min) Alarm at 3 Times Background (Min) I-131, 2 x 10-8 µCi/cc 0.48 1.4 Cs-137, 6 x 10-8 µCi/cc 0.3 8 1.1 2. Fuel Handling Building Exhaust Use of radiation monitor, RM
-A6, in the Fuel Handling Building exhaust would provide the following detection capability under the previously stated assumed conditions, based upon the discharge flow rates shown by Figure 12.2-2. The exhaust air flow from the Fuel Handling Building is approximately 2 7 , 000 cfm. This flow is monitored by RM
-A6, a three channel monitor, which samples the air in the discharge duct upstream of the filter plenum through an isokinetic nozzle. By use of a dilution factor, based upon the ratio of sub
-area exhaust air flow to total air flow, an estimate of detection times can be determined as follows:
Detection time for one DA C in sub-area = Detection time for one DA C Dilution ratio Estimates of detection times for I
-131 and Cs
-137 obtained from the preceding expression are presented in Table 12.2-4. RN 01-119 RN 01-119 RN 01-119 RN 01-119 12.2-11 Reformatted May 2018 12.2.4.3.3 Auxiliary Building Normally accessible areas of the Auxiliary Building are supplied with clean air which then passes through such areas to restricted access areas with potentially high airborne activity levels. Use of a movable surveillance monitor, such as RM
-A12, wit h an assumed sensitivity of 1.0 x 10-11 µCi/cc for cesium would provide the following detection capability:
Where: 6 x 10-8 µCi/cc is DAC for cesium x is the time to detect one DAC, local activity (i.e., 0.1 min). With the alarm set at 3 times background, the response to one DAC of Cs-137 in the area under surveillance would be approximately 0.
3 minutes. Periodic surveillance sampling by Health Physics personnel will provide samples for laboratory analysis of particulates and radioiodine to verify operational levels of airborne activity in the plant.
12.2.4.4 Reactor Coolant Leak Detection Assumptions relative to reactor coolant leak detection are as follows:
- 1. Free containment volume, 1.8 x 10 6 ft 3. 2. Continuous purge rate, approximately 1000 cfm.
- 3. Reactor Building Charcoal Cleanup System, not operating.
- 4. Reactor coolant activity, as listed below for the predominate isotopes
. 5. Sensitivity of radiation monitor RM
-A2, satisfies requirements of Regulatory Guide 1.45. RN 01-119 RN 13-011 12.2-12 Reformatted May 2018 The major isotopes of interest and corresponding design basis activities for both the particulate and gas channels are as follows:
- 1. Cs-134, 2.6 x 10
-2 µCi/gm. 2. Cs-137, 1.9 x 10
-2 µCi/gm. 3. Co-58, 1.7 x 10
-2 µCi/gm. 4. Co-60, 2.1 x 10
-3 µCi/gm. 5. R b-88, 2.3 x 10
-1 µCi/gm. 6. Xe-133, 5.1 µCi/gm (gas).
Assuming a steady reactor coolant leak rate of 0.1 gpm, the equilibrium concentrations of particulate isotopes in the reactor building atmosphere are as follows:
- 1. Cs-134, 7.38 x 10-8 µCi/cc. 2. Cs-137, 5.4 0 x 10-8 µCi/cc. 3. Co-58, 4.77 x 10
-8 µCi/cc. 4. Co-60, 5.96 x 10-9 µCi/cc. 5. Rb-88, 9.19 x 10
-9 µCi/cc. A step increase in leakage to 1 gpm for a period of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> would increase total particulate activity by 75 percent which is readily detectable by the particulate channel of radiation monitor RM
-A2. Figure 12.2
-3 shows the increase in the RB particulate concentration following a 1
-gpm leak. The major isotope of interest for gas channel detection is Xe
-133. A reactor coolant leak of 0.1 gpm would result in an equilibrium Xe
-133 concentration of 4.14 x 10-5 µCi/cc. A subsequent leak of 1 gpm over 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> would result in an increase of 1.5 5 x 10-5 µCi/cc. This is equivalent to a 37 percent increase which is detectable by the gas channel of radiation monitor RM
-A2. Figure 12.2-4 shows the increase in Xe
-133 concentration.
RN 13-011 12.2-13 Reformatted May 2018 12.2.5 OPERATING PROCEDURES The Health Physics group is responsible for developing procedures for evaluating potential airborne radioactivity concentrations and providing guidance for minimizing personnel exposures. Occupational exposure is minimized during operations and maintenance by using the following methods and procedures to determine and cope with potential hazards:
- 1. Monitoring High volume air samples of various flow rates are used to collect particulates on high efficiency filter media, at regularly scheduled intervals, for subsequent counting. For tritium sampling, freezeout methods, bubblers, or desiccants are used to obtain samples for counting by the use of liquid scintillation techniques. Assay of noble gases is performed on a regular schedule by drawing an air sample into an evacuated chamber for appropriate analysis.
- 2. Respiratory Protection It is the responsibility of the Health Physics group to monitor and post areas of airborne radioactivity, to establish the requirements for respiratory equipment, to control the use of respiratory equipment, and to control access to areas through the radiation work permit program. Training programs for respiratory protection are the responsibility of Health Physics Supervision. Experience gained during operation and maintenance of several nuclear plants with whom SCE&G has contact is used to provide one basis for further evaluation and development of respiratory protection programs. Guidance contained in Regulatory Guides 8.2, 8.8, and 8.10 is utilized in the development and review of these programs.
In relation to TMI Action Plan Item II.F.1, "Additional Accident Monitoring Instrumentation," station procedures will contain the following information for converting instrument readings to concentrations or/and release rates:
a) Graphs relating cpm readings to concentration (µCi/ml) for effluent radiation measurements from onsite analyses.
b) Graph or formula for determining the release rate (Ci/sec) based on effluent radiation monitor readings and measured flow rates of the main vent.
RN 18-016 12.2-14 Reformatted May 2018 c) Graph or formula for determining the volume of steam discharged after opening of main steam safety valves. A concentration based on the average reading of the radiation monitors can be used to quickly approximate the total amount of radioactivity released. Subsequent laboratory analysis more accurately determines the quantity and spectrum of radionuclides released.
Computer capabilities can also be used to assist with these calculations.
Also, as required by TMI Action Plan Item II.F.1, the Station Radiation Monitor Calibration Program is as follows:
Initial vendor calibration included the determination of response to various radioactive isotopes where they were calibrated to provide traceability to the National Bureau of Standards. The Liquid monitors were checked against Cs
-137 and Mn-54; Particulate monitors were checked against Cs
-137 and Ce
-144; Iodine monitors were checked against Cs
-137 and Ba
-133; Gas monitors were checked against Kr
-85 and Cs-137. The Condenser Offgas monitor was checked against Xe-133 and Cs
-137. Area monitors were checked against Ra
-226. Inplant calibration will normally use calibrated sources for determination of monitor response. These sources will typically be Cs
-137 or Co-60 for Area Gamma monitors; Cs
-137 for Particulate monitors; Ba
-133 for Iodine monitors; and Cs
-137 for Liquid monitors. Frequency of periodic calibration is normally on a yearly basis except for those channels identified in the Technical Specification where frequency has been fixed. The High Range Gamma Area monitors require electronic verification as described in Section 12.1 as the use of high level isotopes is not practical.
12.2.6 ESTIMATES OF INHALATION DOSES The annual inhalation doses to plant personnel from airborne activity in the various plant buildings depend upon the occupancy of the various plant areas in which airborne activity can occur. The dose to plant personnel is controlled by limiting personnel occupancy in contaminated areas
, using engineering controls when available, and by using respiratory protection equipment when warranted by TEDE
-ALARA evaluation of the task being performed.
The doses to plant personnel are therefore limited to the values specified in 10 CFR 20 for occupationally exposed individuals.
Sections 12.2.6.1.1 through 12.2.6.1.3 discuss peak airborne concentrations and inhalation dose rates for various plant buildings based upon the leak rates discussed in Section 12.2.3. The methods used to calculate concentrations and inhalation dose rates are discussed in Section 12.2.6.2. RN 01-119 12.2-15 Reformatted May 2018 12.2.6.1 Peak Airborne Concentrations and Inhalation Dose Rates 12.2.6.1.1 Reactor Building Peak airborne concentrations for the Reactor Building during operation at power are presented in Table 12.2-1. The concentrations presented in Table 12.2-1 are those that would occur at the end of the interval between purges with the assumptions given in Section 12.2.3.1. Exposure to the reactor building concentrations given in Table 12.2-1 would result in an upper limit inhalation dose rate of 21.9 mRem/hr to the thyroid. Exposure of workers to this dose rate is unlikely since operation of the Reactor Building Charcoal Cleanup System and/or partial purging of the Reactor Building normally occur prior to any lengthy access. Respiratory protection equipment is used for short term access when required by plant procedures.
12.2.6.1.2 Auxiliary Building Average airborne concentrations for the Auxiliary Building were calculated using the assumptions given in Section 12.2.3.2 and the building volume and flow rate discussed in Section 12.2.2. These concentrations are given in Table 12.2-1. The corresponding inhalation dose rate to the thyroid is 1.8 x 10
-2 mRem/hr. As described in Section 9.4.2, the Auxiliary Building Ventilation System supplies clean air to areas expected to be relatively free of airborne activity and removes air from areas that could potentially have high levels of airborne radioactivity. Thus, airborne activity levels in normally occupied areas should be significantly lower than the calculated average concentrations presented in Table 12.2-1. The peak airborne concentrations in the Auxiliary Building are expected to be in the individual rooms which house auxiliary reactor equipment, such as the letdown heat exchanger, volume control tank and connecting instrumentation, piping, and valves.
These rooms are within controlled areas and access to these areas is maintained under strict administrative control. Respiratory protection equipment or other protective measures are used in accordance with plant procedures.
For calculational purposes in determining peak concentrations, it has been assumed that one half of the total leakage in the Auxiliary Building occurs around the letdown heat exchanger. The resultant calculated concentrations for the letdown heat exchanger are presented in Table 12.2-1. The corresponding inhalation dose rate to the thyroid is 2.5 mRem/hr. RN 01-111 RN 01-111 RN 01-111 12.2-16 Reformatted May 2018 12.2.6.1.3 Turbine Building Average airborne concentrations for the Turbine Building were calculated using assumptions given in Section 12.2.3.3 and the building volume and flow rate discussed in Section 12.2.2. These concentrations are given in Table 12.2-1. The corresponding inhalation dose rate to the thyroid is 2.8 x 10
-5 mRem/hr. The Turbine Building concentrations and inhalation dose rate are sufficiently small to allow normal occupancy without the use of protective measures.
12.2.6.2 Methods Used to Estimate Airborne Concentrations and Inhalation Doses The concentration of radionuclides in a given volume, V, with a steady
-state leakage rate is determined from an activity balance. For the i th isotope, the activity balance is as follows: (12.2-1) Where: C i (t) = Concentration of i th isotope at time t (µCi/cc).
S i = Leakage rate of i th isotope (µCi/sec).
i = Removal constant of i th isotope (sec
-1). In Equation (12.2
-1), ingrowth from radioactive parent nuclides has been neglected and a homogeneous mixing model has been assumed. The solution is as follows:
(12.2-2) If the system is purged at a flow rate, R, then, for a volume, V, the removal constant is:
(12.2-3) Where: i = The decay constant of the i th isotope. When an intermittent purging scheme is used, there is a period of buildup followed by a period of removal. During the building interval, the removal constant is:
= i (12.2-4) RN 01-111 12.2-17 Reformatted May 2018 Once the airborne concentrations have been determined, inhalation dose rates are calculated using the following formula:
Inhalation Dose Rate = (C i)(BR)(DCF i) Where: Ci = Equilibrium concentration of isotope i (µCi/cc)
. BR = Breathing rate (cc/hr).
DCF i = Dose conversion factor for isotope i (m Rem/µCi). 12.
2.7 REFERENCES
- 1. U.S. Nuclear Regulatory Commission, "Calculation of Releases of Radioactive Materials in Gaseous and Liquid Effluents from Pressurized Water Reactors," NUREG-0017, April 1976.
- 2. American National Standards Institute, "Guide for Administrative Practices in Radiation Monitoring," ANSI N13.2, 1969.
12.2-18 Reformatted May 2018 (This page intentionally left blank.)
TABLE 12.2-1 CALCULATED AIRBORNE CONCENTRATIONS (1) Isotope Reactor Building Concentrations (2) (Ci/cc) Auxiliary Building Concentrations (Ci/cc) Letdown Heat Exchanger Room Concentrations (3) (Ci/cc) Turbine Building Concentrations (Ci/cc) H-3 8.7 x 10-4 1.4 x 10-8 2.0 x 10-7 3.0 x 10-10 Kr-85m 1.3 x 10-6 2.1 x 10-9 2.9 x 10-7 1.1 x 10-14 Kr-85 9.6 x 10-6 1.6 x 10-10 2.2 x 10-8 8.2 x 10-16 Kr-87 4.3 x 10-7 2.1 x 10-9 3.2 x 10-7 1.2 x 10-14 Kr-88 1.6 x 10-6 3.8 x 10-9 5.4 x 10-7 2.1 x 10-14 Xe-131m 3.0 x 10-5 1.1 x 10-9 1.5 x 10-7 5.4 x 10-15 Xe-133m 2.5 x 10-6 3.4 x 10-10 4.7 x 10-8 1.8 x 10-15 Xe-133 1.1 x 10-4 6.9 x 10-9 9.5 x 10-7 3.6 x 10-14 Xe-135m 8.2 x 10-8 1.4.x 10-9 2.5 x 10-7 1.0 x 10-14 Xe-135 1.2 x 10-5 9.6 x 10-9 1.3 x 10-6 5.1.x 10-14 Xe-137 5.3 x 10-9 1.6 x 10-10 3.9 x 10-8 2.1 x 10-15 Xe-138 7.0 x 10-8 1.2 x 10-9 2.3 x 10-7 9.5 x 10-15 Br-84 2.1 x 10-11 1.6 x 10-12 2.6 x 10-10 3.4 x 10-16 I-131 1.6 x 10-8 5.4 x 10-12 7.4 x 10-10 1.1 x 10-14 I-132 1.2 x 10-9 2.6 x 10-11 3.7 x 10-9 1.6 x 10-14 I-133 6.6 x 10-9 1.7 x 10-11 2.4 x 10-9 2.8 x 10-14 I-134 7.3 x 10-10 3.8 x 10-11 5.8 x 10-9 1.2 x 10-14 I-135 4.1 x 10-9 3.3 x 10-11 4.5 x 10-9 3.6 x 10-14 02-01 (1) Based upon the assumptions given in Sections 12.2.3 and 12.2.6. (2) Concentrations at the end of interval between purges and without operation of the reactor building charcoal cleanup system.
(3) Concentrations are based upon the assumption that one-half of the auxiliary building leakage occurs in the letdown heat exchanger room.
12.2-19 Reformatted Per Amendment 02-01 TABLE 12.2-2 AIR FLOW RATES AND APPROXIMATE NET FREE VOLUMES SERVED BY VENTILATION SYSTEMS System System Exhaust Flow Rate Approximate Net Free Volume Served (ft
- 3) Control Room Ventilation System 21,270 cfm/emergency system fan 226,040 Controlled Access Area Exhaust
System 16,000 cfm/fan 73,890 (1) Spent Fuel Pool Area Ventilation
System 27,000 cfm/fan 629,260 (1) Auxiliary and Radwaste Area
Ventilation Systems 123,800 cfm, total 1,890,000 Turbine Building Ventilation S ystems 1,500,000 cfm, total 3,700,000 Reactor Building Charcoal Cleanup
System 24,000 cfm, total 1,800,000 RN 02-048 RN 02-048 RN 02-048 RN 01-119 (1) Original Licensing / Construction Estimates 12.2-20 Reformatted Per Amendment 02-01 TABLE 12.2-3 AIRBORNE RADIOACTIVITY MONITORS MONITOR FUNCTION DETECTORS POWER SOURCE RM-A1 Control Room Supply Air Monitors ventilation air supplied to control room 1. Particulate-Beta, 4.7 x 10
-11 to 10-7 Ci/cc, Cs-137 2. Iodine-Gamma, 2 x 10
-11 to 2 x 10
-7 Ci/cc, I-131
- 3. Gas-Beta, 2 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 Bus B (1) RM-A2 Reactor Building Air
Sample Line Monitors sample taken
from containment 1. Particulate-Beta, 5.5 x 10
-11 to 10-7 Ci/cc, Cs-137 2. Iodine-Gamma, 2 x 10
-11 to 2 x 10
-7 Ci/cc, I-131
- 3. Gas-Beta, 2.6 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 Bus B (1) RM-A3 Main Plant Vent Exhaust Monitors effluent from
auxiliary building 1. Particulate-Beta, 4.7 x 10
-11 to 10-7 Ci/cc, Cs-137 2. Iodine-Gamma, 2 x 10
-11 to 2 x 10
-7 Ci/cc, I-131
- 3. Gas-Beta, 2.6 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 Bus A (1) RM-A4 Reactor Building Purge Exhaust Monitors effluent from containment during purge 1. Particulate-Beta, 4.7 x 10
-11 to 10-7 Ci/cc, Cs-137 2. Iodine-Gamma, 2 x 10
-11 to 2 x 10
-7 Ci/cc, I-131
- 3. Gas-Beta, 2 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 Bus A (1) RM-A6 Fuel Handling Building Exhaust Monitors ventilation discharge from fuel handling building 1. Particulate-Beta, 4.7 x 10
-11 to 10-7 Ci/cc, Cs-137 2. Iodine-Gamma, 2 x 10
-11 to 2 x 10
-7 Ci/cc, I-131
- 3. Gas-Beta, 2 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 Bus B (1) RN 03-011 12.2-21 Reformatted Per Amendment 02-01 TABLE 12.2-3 (Continued) AIRBORNE RADIOACTIVITY MONITORS MONITOR FUNCTION DETECTORS POWER SOURCE RM-A7 Sampling Rooms Monitors air sample
from sampling room.
Movable unit - may be used for other areas as
required. 1. Particulate-Beta, 4.7 x 10
-11 to 10-7 Ci/cc, Cs-137 2. Iodine-Gamma, 2 x 10
-11 to 2 x 10
-7 Ci/cc, I-131
- 3. Gas-Beta, 2 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 480 volt outlets RM-A8 Spent Fuel Area Monitors local air
sample. Movable unit - may be used for other areas as required. 1. Particulate-Beta, 4.7 x 10
-11 to 10-7 Ci/cc, Cs-137 2. Iodine-Gamma, 2 x 10
-11 to 2 x 10
-7 Ci/cc, I-131
- 3. Gas-Beta, 2 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 480 volt outlets RM-A9 Condenser Air Removal Monitors effluent of condenser off-gas discharge Gas-Gamma, 2 x 10
-6 to 2 x 10
-2 Ci/cc, Xe-133 Bus B RM-A10 Waste Gas Discharge Monitors discharge of waste gas-provides backup to decay tank
analysis Gas-Gamma, 2 x 10
-4 to 2 Ci/cc, Xe-133 Bus B RM-A11 Auxiliary Building
Ventilation Sequentially monitors
various auxiliary building ventilation
exhaust ducts Gas-Beta, 2 x 10
-6 to 2 x 10
-2 Ci/cc, Kr-85 Bus B (1) 02-01 RN 03-011 12.2-22 Reformatted Per Amendment 02-01 Reformatted Per Amendment 02-01 TABLE 12.2-3 (Continued) AIRBORNE RADIOACTIVITY MONITORS MONITOR FUNCTION DETECTORS POWER SOURCE RM-A12 Movable Particulate Unit Provides local
particulate monitoring
and iodine sampling Particulate-Beta, 10
-11 to 10-7 Ci/cc, Cs-137 120 volt outlets RM-A13 Main Plant Vent Exhaust, High Range Gas Discharge Effluent High Range Gas Monitor Ion Chamber - Gamma
0.1 to 10 7 mr/hr (10-2 to 10 5 Ci/cc, Xe-133)
Bus A RM-A14 Purge Exhaust Effluent, High Range Effluent High Range
Gas Monitor Ion Chamber - Gamma
0.1 to 10 7 mr/hr (10-2 to 10 5 Ci/cc, Xe-133)
Bus A RM-G19 A, B, C
Steam Line Steam Line High Range Gamma Monitor Ion Chamber - Gamma
0.1 to 10 7 mr/hr Bus B RN 02-002 RN 03-011 12.2-23 (1) Associated sample pump powered from diesel backed 480 volt bus.
TABLE 12.2-4 ESTIMATED DETECTION TIME FOR I-131 AND Cs-137 IN THE FUEL HANDLING BUILDING Fuel Handling Building Area (1) Exhaust Flow (cfm) Dilution Factor Detection Time (Minutes)
I-131 Cs-137 Spent Fuel Area 15,320 0.567 0.8 0.7 General Flow Area 1,840 0.068 7.0 5.5 Railroad Area 3,020 0.112 4.3 3.4 Personnel Cleanup (2) 242 0.009 53.6 42.0 Emergency Personnel Hatc h 1,750 0.065 7.4 5.8 412 South West 1,470 0.054 8.8 6.9 Decontamination 1,120 0.041 11.6 9.1 Excess Waste Holdup Tank 950 0.035 13.6 10.7 Decontamination Pit
Collection Tank 686 0.025 18.9 14.8 RN 01-119 Notes: 1. Small areas, access to whic h is controlled due to potentia lly high activity levels, are not included since access is under administrative control.
- 2. The personnel cleanup area is listed although it is not considered as a source of activity.
12.2-24 Reformatted Per Amendment 02-01 GENERAL NOTES: 1.<:=DENOTES AIR FLOW.2.....DENOTES FILTER REMOVAL.3.TAG NO.XAA-29A-AH.
4.TAG NO.XAA-29B-AH
- 5.SAFETY CLASS-2b.6.MAXIMUM UNIT CAPACITY 21,000 CFM.7.OPERATING WT.28,149 LB.8.SHIPPING WT.21,714 LB.9.THIS DESIGN IS PRELIMINARY ONLY.THE FINAL DESIGN MAY DEVIATE FROM THIS ARRANGEMENT.
- 10.ALLOW 42" CLEARANCE ABOVE FOR CHARCOAL FILLING.0 11.DblE TO HEIGHT LIMITATIONS FLOOR SLOPE WILL BE APPROX.1/2" IN 11'-0".o..0 3t"*-c, 0:-Iff>-I-",@c ,./0 r-S t@,LIGHT ASSY.(TYP.8 PLACES)COMP DR.a"cvI.
CR.(T"rP-4.PL.)18'-0..0 (}-9...0 0'2.'-102-3 ROUGHING FILTER 3H X 5W@2000 CFM EA.---HECAŽ(2" CHARCOAL/BED)'
_____---.11 BEDS@2000 CFM EA.----------HEPA FILTER-r-T:'_g=--
i-f......".-+!--r-r::;-o"'i-'------=-t-"'-,--,3H X 5W@1500CFMEA.
cr ():: SOUTH CAROLINA ELECTRIC&GAS CO.VIRGILC.SUMMER NUCLEAR STATION Control Room Emergency Charcoal Filter Plenum Figure 12.2 c 1 l..---.;
CONTROL BUILDINGRAD MAINT.
BLDGHOT MACH.SHOPEAST/WEST PENETRATION RM A13 RM A39000 CFM4000 CFM52200 CFMCONTROLLED ACCESSCHARCOAL EXH. FILT.16000 CFMSAMPLING ROOMSAMPLE & LAB.
HOODS MISC. CLEAN AREAS RM A1 RM A7 PLANT VENT 238,188 CFMFUEL HANDLING BUILDINGFUEL HANDLING BUILDINGCHAR. EXH.FILTERS30000 CFM MISC. AREASSPENT FUEL AREA RM A8 RM A615320 CFM575 CFMHOT MACH.SHOP3000 CFMAUXILIARY BUILDINGAUX. BLDG.
HEPAFILTERS39375 CFMAUX. BLDG.HEPA &CHAR. FILT.45680 CFMAUX. BLDG.HEPA &CHAR. FILT.42695 CFMMISC.CONTROLLED AREASMISC.CONTROLLED AREASMISC.CONTROLLED AREASACCESS &CORRIDORSSUPPLY RM A12 RM A11SOUTH CAROLINA ELECTRIC & GAS CO.VIRGIL C. SUMMER NUCLEAR STATIONAirborne Activity MonitoringASSOCIATED WITH FSAR FIGS9.4-4, 9.4-7, 9.4-8, 9.4-9,9.4-10a, 9.4-11, 9.4-26a Figure 12.2-2 Rev. 2SUPPLYRN 01-119June 2006 RN 13-011 SOUTH CAROLINA ELECTRIC & GAS CO.
VIRGIL C. SUMMER NUCLEAR STATION Buildup of Predominate Particulates in Reactor Building From 1 gpm Reactor Coolant Leak as a Function of Time After Leakage Begins Figure 12.2
-3 1.E-081.E-071.E-061.E-050.1 1101001000PARTICULATE CONCENTRATION IN RB (TIME (HOUR)1 GPM PRIMARY COOLANT LEAKAGE IN REACTOR BUILDING PRIMARY COOLANT CONCENTRATIONS PER SECTION 12.2.4.4 PARTITION FACTOR = 0.3 1000 CFM CONTINUOUS PURGE OF REACTOR BUILDING RN 13-011 SOUTH CAROLINA ELECTRIC & GAS CO.
VIRGIL C. SUMMER NUCLEAR STATION Buildup of Xe
-133 in Reactor Building From 1 gpm Reactor Coolant Leak as a Function of Time After Le akage Begins Figure 12.2
-4 1.E-061.E-051.E-041.E-030.1 1101001000 XE-133 CONCENTRATION IN RB (Ci/cc)TIME (HOURS
)1 GPM PRIMARY COOLANT LEAKAGE IN REACTOR BUILDING Xe-133 PRIMARY COOLANT CONCENTRATION OF 5.1 x 10
-5 Ci/gm Xe-133 PARTITION FACTOR = 1 1000 CFM CONTINUOUS PURGE OF REACTOR BUILDING 12.3-1 Reformatted M ay 2018 12.3 HEALTH PHYSICS PROGR AM 12.3.1 OBJECTIVES AND ORGANIZATION 12.3.1.1 Program Objectives 12.3.1.1.1 As Low as Reasonably Achievable (ALARA): Policy Considerations It is the policy of the management of South Carolina Electric and Gas Company (SCE&G) that the Virgil C. Summer Nuclear Station is operated in such a manner that occupational radiation exposures of plant personnel are as low as reasonably achievable (ALARA). This policy is implemented by the Manager, Health Physics Services, who is directly responsible for the ALARA aspects of plant operation, and who also has the authority to prevent operations which are not consistent with the ALARA policy. The Manager, Health Physics Services, is responsible to the General Manager, Nuclear Plant Operations, who has overall responsibility for the implementation of the ALARA policy. T he Manager, Quality Services is responsible for conducting periodic audits of plant operations to determine how exposures might be lowered. The Nuclear Safety Review Committe assure implementation of and adherence to the operational ALARA program. (see Section 13.4.2.2).
The General Manager, Nuclear Plant Operations, has familiarized plant personnel with the commitment to keep occupational exposures ALARA by providing appropriate instructions, policy statements, and training. The General Manager, Nuclear Plant Operations, determines if modifications to operating and maintenance procedures and to plant equipment and facilities should be made, where practicable to minimize exposures and where unresolved safety problems are not involved.
12.3.1.1.2 ALARA: Operational Considerations Procedural guidance in exposure reduction has been established for all systems that contain, collect, store, or transport radioactive liquids, gases, and solids, for all operating conditions. The following are examples of specific exposure
-reduction techniques for operations such as maintenance, inservice inspection, radwaste handling, and refueling:
- 1. During initial startup, neutron and gamma
-ray dose rate surveys are performed to verify the adequacy of shielding.
- 2. During normal operations, dose rate, surface contamination, and airborne radioactivity surveys are performed periodically throughout the plant and areas are zoned accordingly. These surveys ensure that data is available for planning operation and maintenance activities in accordance with the ALARA objective of minimizing exposures.
RN 99-129 RN 17-030 RN 13-005 RN 99-129 99-161 12.3-2 Reformatted M ay 2018 3. Areas are conspicuously posted in accordance with 10 CFR 20, as appropriate.
- 4. A radiation work permit (RWP) system is employed to ensure proper administrative control over work in restricted areas. The RWP is designed to ensure that the radiological conditions are defined and that appropriate measures are taken to minimize the dose received by personnel. Section 12.3.2.3.7 explains the use of the RWP. 5. Extension tools are used when practicable to increase the distance between the radiation source and the worker.
- 6. Equipment is moved to areas with lower radiation fields for maintenance when practicable.
- 7. Portable shielding such as lead bricks, lead sheets, lead shot, high density concrete block, or steel plates are used as practicable for assuring ALARA doses.
- 8. A personnel dosimetry program as described in Section 12.3.3 is administered by the Health Physics group to ensure compliance with 10 CFR 20.
Administrative controls have been established to assure that all procedures and requirements relating to radiation protection are followed by all plant personnel. The procedures that control radiation exposure are subject to review and approval as outlined in Section 13.4.
In general, the plant procedures are designed to keep occupational radiation exposures ALARA and follow the recommendations of Regulatory Guides 8.8 and 8.10. These procedures are organized and revised by the Manager, Health Physics Services, in cooperation with the Maintenance, Technical Services, or Operations Manager, such that operations proceed within the framework of the ALARA policy.
Independent technical and quality oversight is provided by the Manager, Quality Services. This organization, through audits, surveillances, and reviews as described in the Quality Assurance Program Description (QAPD), provides input to the Nuclear Safety Review Committee. Since the Manager, Quality Services maintains a reporting chain independent of plant operations to the Vice President, Nuclear Operations continuing implementation of and adherence to the operational ALARA program is assured. RN 99-129 RNs97-068 13-005 17-001 17-030 12.3-3 Reformatted M ay 2018 12.3.1.2 Program Organization The Manager, Health Physics Services, has the authority for developing and implementing company policy for radiation protection and contamination control. The administration of the Health Physics program is also the responsibility of the Manager, Health Physics Services, whose minimum qualifications are as presented in Section 13.1.3. The Manager, Health Physics Services, reports directly to the General Manager, Nuclear Plant Operations, on radiological protection issues.
The Manager, Health Physics Services is responsible for keeping plant staff informed of radiation hazards and conditions related to potential exposure, contamination of plant equipment or contamination of site and environs (see Figure 1 2.3-1). As the administrator of the health physics program, the responsibilities of the Manager, Health Physics Services include:
- 1. Training and supervision of the Health Physics staff.
- 2. Planning and scheduling Health Physics activities.
- 3. Establishing and maintaining data on plant, environmental and laboratory radiation and contamination levels, personnel exposures, and work or effluent release restrictions.
- 4. Maintaining a current Health Physics manual which contains the standards and procedures to implement the ALARA policy for radiation exposures and effluent releases. 5. Ensuring that plant operations comply with applicable regulations pertaining to radiation and environmental radiological protection.
- 6. Assessing radiological conditions/issues for normal operations and emergencies and advising plant management or the emergency director.
- 7. Developing, implementing, directing, controlling, and supervising all aspects of the RWP, ALARA, Effluent Control, Radiological Environmental, Radwaste, Dosimetry, Radiological Respiratory Protection, Equipment CAL/Contamination Control, Surveillance, RCA Access, and Radiological Data Base Programs.
- 8. Controlling the receipt, shipment, and storage of all radioactive materials.
- 9. Providing radiological engineering expertise and assessing events, occurrences, program performance, and data while developing and implementing solutions and enhancements.
- 10. Reviewing radiation safety
-related operating procedures.
RN 99-129 RN 99-129 R N 18-016 12.3-4 Reformatted M ay 2018 The Manager of Health Physics Services is responsible for developing a radiation protection training program, a radiation surveillance program, and an effluent control program to ensure that radiation exposures of all personnel are kept as far below the limits of 10 CFR 20 as is reasonable achievable. He also develops policy and specific procedural guidance as necessary to implement the ALARA policy.
In order to carry out his responsibilities, the Manager of Health Physics Services is in charge of the Health Physics groups. These groups are made up of technicians, supervisors, and professional Health Physicists who meet the qualifications presented in Section 13.1.3.
The Health Physics groups are organized to provide the following services:
- 1. Establish and maintain a radiological surveillance program to routinely collect, post, and record data concerning radiation and contamination levels, both surface and airborne, throughout the plant.
- 2. Perform radiation monitoring for special plant operations and specific maintenance activities as required and maintain records of the surveys performed.
- 4. Provide for effective access control by establishing zones throughout the plant, based on radiation and contamination levels. 5. Provide, maintain, and instruct plant personnel in the proper use of protective clothing and respiratory equipment for plant operation and maintenance.
- 6. Provide procedures for dealing with radiation hazards in performing day to day operations and maintenance and verify the effectiveness of such procedures.
- 7. Develop and implement the personnel dosimetry and respiratory protection programs. 8. Assist in the plant personnel training and emergency preparedness programs by providing specialized training in radiation protection and expertise/manpower for emergency response and scenario development.
- 9. Make recommendations for performing equipment, area, and personnel decontamination.
- 10. Receive and ship radioactive materials, including special nuclear, source, and by-product material to ensure compliance with Federal and State regulations.
RN 99-129 RN 99-129 12.3-5 Reformatted M ay 2018 11. Calibrate and maintain Health Physics, laboratory, and dosimetry equipment and facilities.
- 12. Sample, analyze, and perform calculations necessary to ensure that radioactivity discharged to the environment in effluents is kept as far below established limits as is reasonably achievable.
- 13. Assess internal exposures and maintain official dose records.
- 14. Provide oversight and direction to the chosen dosimetry processor in processing Radiological Environmental and site personnel TLDs.
- 15. Develop, direct, and implement the Radwaste Process and Minimization program.
- 16. Develop and maintain the ODCM, serve as member of PSRC, and as Radiation Safety Officer for various DHEC rad material licenses.
The Health Physics section supervises the implementation of the procedures specified by the Manager, Health Physics Services, for personnel and environment exposure reduction during normal operations, maintenance, inservice inspection, radwaste handling, and refueling in accordance with ALARA policy.
12.3.2 FACILITIES, EQUIPMENT, AND PROCEDURES 12.3.2.1 Facilities 12.3.2.1.1 Health Physics Facilities The Health Physics facilities consist of:
- 1. A Health Physics room and instrument storage area, sampling room, counting room, personnel decontamination area, locker room, and laundry elevation of the Control Building.
- 2. Health Physics station(s), containing protection clothing, portable surve y equipment, and other Health Physics materials at locations around the plant
, as specified by the Manager, Health Physics Services to be of strategic importance for contamination and exposure control.
- 3. A Health Physics facility for Dosimetry, Whole Body Counting, and Radiological Respiratory Protection.
- 4. An offsite Radiological Support facility located at the Environmental Lab which provides laboratory and equipment resources necessary for the radiological, environmental, and emergency response programs
. RN 99-163 RN 99-163 RN 99-129 RN 14-034 RN 17-030 RN 17-030 RN 18-016 12.3-6 Reformatted M ay 2018 The 12.1-19 and 12.1
-20 to illustrate the layout of the access control area Health Physics facilities.
12.3.2.1.2 Instrument Storage, Calibration, and Maintenance Facilities Portable instruments for routine Health Physics surveys are stored in the Health Physics areas around the CB412 HP Lab, RCA Access Control Point, and AB412 HP Instrument Calibration Facility.
Other portable instruments are located at Health Physics stations around the plant (see Section 12.3.2.2.2) and at the Environmental Lab. Portable instruments for emergency use are stored at strategic locations around the plant , Environmental Lab, and other approved offsite locations.
Portable instruments and laboratory equipment are routinely maintained and calibrated by Health Physics personnel or by returning the instruments to the manufacturer for repair. 12.3.2.1.2.1 Personnel Contamination Control Facilities The primary contamination control facility for personnel is the access control area, which is illustrated in Figure 12.1
-19. Additional contamination control points are established in the immediate vicinity of known contaminated areas, as necessary, to prevent the spread of contamination. These points provide a controlled interface between the clean and contaminated areas. The personnel decontamination showers are shown in Figure 12.1
-19. Additionally, emergency showers are located around the plant in areas with a high potential for personnel contamination.
Personnel are checked for contamination with the equipment described in Table 12.3
-1. 12.3.2.1.2.2 Equipment Contamination Control Facilities An equipment decontamination area is located adjacent to the radwaste processing area of the Auxiliary Building.
This facility contains installed and portable decontamination equipment. A decontamination area for spent fuel shipping casks is also provided, and is located in the Fuel Handling Building.
12.3.2.2 Equipment 12.3.2.2.1 Selection Criteria The equipment and instrumentation used in the Health Physics program for the assessment of radioactivity and personnel exposures are selected according to the following criteria:
- 1. Ability to measure the quantity of interest to an acceptable degree of precision and a ccuracy. RN 99-164 RN 14-034 12.3-7 Reformatted M ay 2018 2. Ease of operation, maintenance, and calibration.
- 3. Appropriate sensitivity and range for various operational situations, including normal operations, anticipated operational occurrences, and accident conditions, as determined by the requirements of applicable regulations pertaining to each measurement situation.
These criteria apply to portable instrumentation for radiation and contamination surveys, laboratory technical equipment, inplant airborne radioactivity monitoring and sampling equipment, area monitors, and personnel monitoring equipment.
12.3.2.2.2 Protective Clothing and Equipment The following respiratory protection devices are made available at the plant: 1. Full face particulate filter masks.
- 2. Full face masks with air line respirator.
- 3. Hoods or suits with air line respirator.
- 4. Full-face masks with self contained breathing apparatus of the bottle air or chemox type. Protective clothing is required in contaminated areas or in areas where the potential for radioactive material contamination exists. Protective clothing available at the plant includes the following:
- 1. Coveralls.
- 2. Laboratory coats.
- 3. Plastic suits.
- 4. Disposable caps.
- 5. Hoods. 6. Plastic and rubber shoe covers.
- 7. Plastic, rubber, and cotton glo ves. 8. Disposable protective clothing.
RN 14-034 12.3-8 Reformatted M ay 2018 This protective clothing and equipment is located in strategic locations around the plant, as specified by the Manager, Health Physics Services
. The protective clothing and equipment is readily available at key location(s) throughout the plant, without the need to return to the protective clothing storage and issue area to obtain this equipment. Also, protective clothing and equipment is provided in the emergency kits located around, and outside, the plant.
1 2.3.2.2.3 Technical Equipment and Instrumentation The equipment and instrumentation necessary to measure radioactivity, radiation fields, and exposures falls into two major categories:
- 1. Fixed or installed.
- 2. Portable. The fixed equipment includes the Radiation Monitoring System, access
-control contamination monitors, radiochemistry laboratory equipment, personnel dosimetry readout equipment, and the counting room radioactivity analysis instrumentation. The portable equipment includes radiation and contamination survey instruments, airborne radioactivity samplers, movable airborne radioactivity monitor, and personnel dosimeters.
The Radiation Monitoring System is described in Sections 11.4, 12.1.4, and 12.2.4. The access-control contamination monitors are described in Table 12.3
-1. The sensitivity of these monitors is a function of the background level at the location of the monitor; the monitors are shielded to the extent practicable in order to increase their sensitivity. The radiochemistry laboratory equipment includes fume hoods, analytical balances, glassware, reagents, and other materials and equipment as required to perform analyses for personnel protection, radioactivity surveys, and related health physics functions. The counting room instrumentation is described in Table 12.3
-2. The portable Health Physics equipment is described in Table 12.3
-3. These devices are calibrated at least annually and also after any major maintenance is performed on an instrument. These calibrations are performed using a source of the appropriate type directly or indirectly traceable to the National Institute of Standards and Technology.
12.3.2.2.4 Accident Radiation Monitoring In-plant accident radiation monitoring combines the use of fixed radiation monito ring equipment and the use of portable monitoring instrumentation.
Area gamma radiation monitors and atmospheric radiation monitors are described in Sections 12.1.4 and 12.2.4. Portable monitoring instrumentation is tabulated in Table 12.3-3. RN 00-038 RN 02-049 RN 14-034 RN 17-030 RN 17-030 12.3-9 Reformatted M ay 2018 The fixed radiation monitors (area and airborne) are supplied with diesel backed power and are designed to operate in the normal and anticipated operational environment (see Tables 12.1
-20 and 3.11
-3), except that the area monitors in the Reactor Building are not required to withstand LOCA environment. This function is performed by area monitor, RM
-G7, as described in Section 12.1.4.
In the event of an unplanned gas release involving high concentrations of noble gases, silver zeolite filter cartridges will be used for sampling atmospheres as conditions dictate. Silver zeolite cartridges do not significantly absorb noble gases, enabling a more accurate determination of the radioiodine collected. Fixed process radiation monitors, portable continuous air monitors, and grab samplers can utilize silver zeolite cartridges. Table 12.3
-3 outlines the types and quantities of portable air samplers available. Table 11.4
-1 lists the fixed process radiation monitors which detect radioiodine.
Normal laboratory instrumentation, i.e., Intrinsic Germanium detectors and a gas flow proportional counter, will be utilized to determine the quantity of radioiodine collected on a filter cartridge. Counting equipment is available at the Environmental Lab if normal laboratory instrumentation is inoperable.
Health Physics procedures include provisions for determining iodine concentrations in noble gas environments. Health Physics personnel are trained on action levels requiring the use of silver zeolite cartridges and the use of portable single channel analyzers and NaI detectors. This meets the requirements of NUREG
-0578 Section 2.1.8.C. 12.3.2.3 Health Physics Program: Procedures It is the intent of SCE&G that the Health Physics Procedures discussed in this section will conform with 10 CFR 20 and follow the recommendations contained in Regulatory Guides 8.7, 8.8, 8.9, and 8.10.
12.3.2.3.1 Radiation Surveys 12.3.2.3.1.1 Radiation Field Surveys The Health Physics group conducts routine measurements of radiation field intensities around the plant, using portable instrumentation appropriate for the type(s) of radiation present, on a schedule which is determined by:
- 1. The level of radiation exposure rate.
- 2. The variability of radiation level.
- 3. The occupancy factor of the location.
RN 17-030 RN 99-162 12.3-10 Reformatted M ay 2018 Routine radiation field survey frequencies could increase or decrease due to plant conditions. Locations of strategic importance for ALARA (high exposure rate and occupancy) are routinely surveyed and the latest measured values are documented and available for review prior to work in these areas. Trending of specific areas, such as those containing RHR, and letdown system components is done on a routine basis to provide job planning information in such areas. Records are maintained of the results of these surveys as required by 10CFR20.
Prior to the initiation of any operation for which a RWP is required (see Section 12.3.2.3.7) a survey is made of the radiation field(s) in the vicinity where the operation is to be performed, using instrumentation appropriate for the type(s) of radiation present. The results of this survey are recorded electronically, on paper or in the RWP.
Further aspects of radiation
-field surveys are discussed in Section 12.3.2.3.2, and the portable instruments are discussed in Section 12.3.2.2.3.
12.3.2.3.1.2 Surface Contamination Surveys The Health Physics Services group conducts routine surface contamination surveys at locations around the plant, including the access control areas, administrative area, lunchrooms, control room, and main entrance security gate. All locations of importance for controlling the potential spread of contamination are surveyed at least weekly, using the "smear" technique, or an appropriate portable instrument, and the remaining locations are surveyed at least monthly. These survey frequencies could increase or decrease due to plant conditions. The results of these surveys are recorded and tabulated by locations so that trends in the data may be readily observed.
Contamination surveys are also made on personnel, equipment, and materials from time to time as necessary to ensure complete control over the levels and spread of removable contamination. Further aspects of contamination control are discussed in Sections 12.3.2.3.3 and 12.3.2.1.
12.3.2.3.1.3 Airborne Radioactivity Surveys Levels of airborne radioactivity are assessed on a routine basis to ensure compliance with 10 CFR 20. These assessments are performed using equipment and techniques appropriate for the type(s) of radioactivity present at the sampling locations.
Any operation requiring respiratory protection will have the results of airborne radioactivity in ci/cc placed on the radiation work permit for that operation. The airborne radioactivity may be assessed prior to the operation but must be assessed during the operation.
RN 99-164 RN 99-129 RN 17-030 12.3-11 Reformatted M ay 2018 The results of routine airborne radioactivity surveys are recorded by location so that trends in the radioactivity level can be readily identified. Air sampling surveys are performed at least daily in areas with both high occupancy factor and a high potential for the existence of airborne radioactivity. Other locations are surveyed weekly or monthly, as a function of the significance of the location as a source of occupational radiation exposure (ORE) from airborne radioactivity. These survey frequencies could increase or decrease due to the plant conditions. Section 12.3.2.3.4 contains further discussion of airborne radioactivity surveys.
12.3.2.3.2 Radiation Area Access Control All areas of the plant are subject to access control restrictions to an extent proportional to the potential for ORE in each area. The particular access control requirements for each area are specified by the Manager of Health Physics Services.
Specifically, any area of the plant in which the radiation level is at least 100 mrem/hr at 12 inches (30 cm) from a radiation source or from any surface that the radiation penetrate s will be declared a "high radiation area", and access to such areas is restricted. These areas are posted and secured in accordance with 10 CFR 20. Physical barriers to control access to high radiation areas include: locked and/or annunciated doors or gates, fences, or rope barriers. These barriers are arranged in such a manner as to allow exit from the area without a key or other special device.
Administrative measures for access control to high radiation areas include the use of an RWP for operations taking place in such areas. The estimated exposure for individuals entering such areas is based on radiation surveys made prior to, or at the start of work, and the nature of the operation to be performed. Again
, depending upon the operation, a health physics technician may be assigned to supervise stay times and make appropriate surveys while the operation is in progress. 12.3.2.3.3 Contamination Control Surveys for contamination control are performed by the Health Physics Services group on a routine basis at various locations around the plant (see Section 12.3.2.3.1.2). Nonroutine surveys are also made whenever there is a possibility of the spread of contamination by personnel, equipment, or materials.
Since the complete removal of surface contamination from parts of the plant is a practical impossibility, certain plant areas may be designated as "contamination areas". The level of contamination and the number of these areas are reduced to the minimum practicable level, and control points are established to prevent the spread of contamination to other plant areas. Entrance to such an area requires complianc e with the protective clothing and equipment requirements specified by Health Physics. These areas are conspicuously posted and roped off from normal traffic. Such areas are under the supervision of the Health Physics Services group.
RN 99-159 RN 99-159 RN 99-129 RN 99-129 RN 99-129 RN 14-034 12.3-12 Reformatted M ay 2018 Personnel shall be checked for contamination immediately after exiting a contaminated area at the nearest personnel monitor, or by standing on a "hand
-and-foot" or "portal" monitor for a predetermined length of time or by portable Health Physics instrumentation. Permanent personnel contamination monitors are located so that an intercom station is close enough that help can be summoned if necessary.
Any equipment or materials leaving a potentially contaminated area, and all equipment or materials leaving the plant radiation controlled area, will be surveyed for surface contamination and nonremovable radioactivity using smears and/or portable instruments of appropriate sensitivity.
Items of appropriate size may also be placed in the Tool and Equipment Monitor (TEM) for release from the plant radiation controlled area. 12.3.2.3.4 Airborne Radioactivity Assessment and Control Airborne radioactivity is routinely assessed using local sampling, moveable air monitors, and the installed Radiation Monitoring System. Airborne radioactive materials (particulates, noble gases, halogens, tritium) are sampled and analyzed using appropriate techniques. Since local sampling will provide better estimates of airborne contamination levels existing in a work area than will a monitor reading, such special air sampling is used in the RWP program to keep ORE due to airborne radioactivity ALARA. Moveable air monitors and the installed airborne radioactivity monitors are used to provide alarm indications and additional information which is used with local sampling for the assessment of airborne radioactivity.
Airborne radioactivity is controlled by minimizing to the extent practical the sources of this radioactivity, such as surface contamination and leaking valves; and confining unavoidable or accidental releases of airborne radioactivity in plant areas through the use of the ventilation system.
12.3.2.3.5 Respiratory Protection The respiratory protection equipment available at the plant is listed in Section 12.3.2.2.2. The issuance of this equipment is specified, when necessary, as part of the RWP program, on the basis of special air sampling conducted in areas where work is being performed. This equipment is selected and maintained by the Health Physics group. The fitting and training programs for respiratory protection equipment is the responsibility of the Manager of Health Physics Services. Training is required prior to the use of respiratory protection equipment. Depending on the type of respirator, a fit test and medical evaluation are required.
12.3.2.3.6 Radioactive Materials Handling Radioactive materials, sealed or unsealed, are handled and stored in such a manner that ORE will be kept ALARA.
RN 99-129 RN 17-030 RN 17-030 12.3-13 Reformatted M ay 2018 Examples of specific methods of handling and storage of radioactive materials to meet this objective include:
- 1. Minimizing the distance that radioactive samples are transported by personnel.
- 2. Use of shielded sample transporters as appropriate.
- 3. Storage of calibration sources in appropriately shielded, labeled, and secured container s. 4. Use of remote actuators or similar devices to maximize the distance of personnel from high level sources.
- 5. Maintenance of accurate source activity inventories on all calibration sources.
Procedures are written and implemented by the Manager of Health Physics Services for the handling of radioactive materials, including procedures for the safe recovery from radioactive spills or source leakage.
12.3.2.3.7 Radiation Work Permit Program A RWP program is established as an integral part of the ALARA policy implementation, and is the responsibility of the Manager of Health Physics Services. A RWP may, at the discretion of the Manager of Health Physics Services, be required for any operation (including maintenance, adjustments, calibrations, inspections, or normal operations) which: 1. Takes place in a radiation, high radiation, or airborne radiation area, as defined in 10 CFR 20 or in a contaminated area as specified in the plant administrative procedures.
- 2. Involves maintenance or other adjustments to any system or component which contains, stores, transports, or collects radioactive materials.
- 3. In the judgement of the Manager of Health Physics Services warrants the issuance of a RWP prior to initiating the operations.
The primary objectives of the RWP program are:
- 1. To ensure that the radiological conditions associated with operations involving radioactive materials, directly or indirectly, are known as accurately as possible.
- 2. To ensure that appropriate and adequate protective measures are taken against these conditions.
RN 99-129 RN 99-129 RN 99-129 12.3-14 Reformatted M ay 2018 3. To ensure that the personnel involved in these operations are aware of the radiological conditions and required protective measures associated with the operation.
- 4. To ensure that the Manager of Health Physics Services, Health Physicist, Field Operations, or the HP Shift Leader are aware of such operations, and approves of the required protective measures. This approval will be indicated by the signature of any of the previously mentioned individuals on the RWP f orm. 5. Provides a means for tracking radiation dose by group, job, location, and component.
The assessment of the radiological conditions associated with operations requiring the issuance of a RWP is performed by the Health Physics Services group. The protective measures taken to mitigate these conditions will be subject to the approval of the Manager of Health Physics Services.
Examples of such measures include:
- 1. Requiring the use of personnel protective clothing and equipment, as appropriate, for the conditions involved.
- 2. Limitation of stay time in radiation/radioactivity areas.
- 3. The use of temporary shielding, temporary containments, remote handling devices, or other techniques to minimize the conditions in the operation area.
The RWP form is used to record the total estimated exposure received as derived from the personnel dosimetry readings in order to acquire a total estimated man
-rem figure. The actual stay time and estimated exposure of each individual in the RWP
-controlled area is recorded electronically via computer or on a dose card. At the discretion of a Health Physicist, Health Physics group personnel may be assigned to supervise the operation. Personnel involved in the operation acknowledge (by their signature on the RWP form or other appropriate documents) their commitment to the ALARA policy and their obligation to abide by the radiological protection decisions of the Health Physics group personnel. 12.3.2.3.8 Radiation Protection Program Review The Manager of Health Physics Services is responsible for conducting an ongoing review of the plant radiation protection program, with the primary objective of finding means to reduce ORE as far below the limits of 10 CFR 20 as reasonably achievable. This review includes an analysis of the following aspects of the program:
RN 99-129 98-01 RN 99-129 RN 99-165 12.3-15 Reformatted M ay 2018 1. Personnel exposures, as indicated by RWP data and periodic dosimetry readings, to identify trends and identify groups or individuals that are receiving large doses.
- 2. Radiation survey data, to identify trends in exposure or contamination levels for various locations around the plant.
- 3. practical.
- 4. Equipment and facilities, to determine where improvements are practical.
In addition to these reviews, management provides independent audit functions as described in Section 12.3.1.1.1.
12.3.2.3.9 Radiation Protection Training Plant personnel, both permanently assigned and temporary, receive training in the principles of radiation protection commensurate with the degree of hazard associated with their respective work assignments. Such training encompass at least the following topics: 1. Properties of radiation and radioactivity.
- 2. Biological effects of radiation on humans.
- 3. Measurement of radiation and radioactivity.
- 4. Principles and techniques of radiation protection.
- 5. General regulatory and specific facility license radiation protection require ments. 6. Specific procedures appropriate for particular work assignments.
- 7. ALARA concept and management commitment thereto.
Personnel who are reassigned to positions involving a greater degree of radiation hazard are retrained and tested at the higher level of radiation protection proficiency required for that assignment. The Manager of Health Physics Services approves the content of the radiation protection training program.
RN 99-129 12.3-16 Reformatted M ay 2018 12.3.3 PERSONNEL DOSIMETRY 12.3.3.1 External Radiation Exposure Plant employees, visitors, and support personnel who enter the radiation controlled area are required to wear personnel dosimetry. The type of dosimetry issued is based upon expected radiological conditions. Neutron exposure is tracked using staytime and exposure rate calculations and/or is measured (for record) using neutron sensitive dosimetry or calculations, as appropriate. Beta and gamma exposure is tracked/controlled using pocket dosimeters, electronic dosimeters, calculations, or secondary thermoluminescent dosimeters (TLDs) as appropriate. Beta and gamma exposure is measured (for record) by TLD or by calculation/investigation in unusual circumstances. TLDs are processed periodically, not to exceed annually, by a NVLAP accredited processor. TLDs may be processed more frequently during outages, are kept for each individual in accordance with the recommendations of Regulatory Guide 8.7. The results of the personnel dosimetry measurements are periodically analyzed to find trends in exposures, identify groups or individuals whose exposures are consistently high, and to find methods of reducing these exposures.
12.3.3.2 Internal Radiation Exposure Internal radiation exposure is assessed using whole body counting and bioassay techniques and estimated where appropriate by calculational methods. The concepts, models, equations, and assumptions used for the assessment of internal radiation exposure follow the recommendations of Regulatory Guide 8.9 or those regulations/regulatory guides in effect at the time. All personnel who regularly enter areas where the potential exists for inhalation, ingestion, or absorption of radioactive materials are routinely assessed for internal contamination. Nonroutine internal radioactivity assessments are made whenever there is reasonable chance that personnel have inhaled, ingested, or absorbed radioactive materials.
RN 00-017 RN 06-017 RN 17-030 12.3-17 Reformatted M ay 2018 TABLE 12.3
-1 CONTAMINATION CONTROL MONITORS INSTRUMENT TYPE REMARKS Portal Monitor Alarm sounds on high activity or insufficient length of count. Controls egress from potentially contaminated areas.
"Frisker" "Pancake" type detector for quick contamination checks of personnel or equipment.
RN 99-162 RN 99-164 12.3-18 Reformatted M ay 2018 TABLE 12.3
-2 FIXED LABORATORY INSTRUMENTATION INSTRUMENT DETECTOR SENSITIVITY(1) NUMBER LOCATION REMARKS Low Background Gas Flow Proportional Counter Proportional Counter 200 dpm 2 412' CB Used for counting alpha/beta smears, residue from evaporated water and radiochemistry samples; equipped with automatic sample chamber.
Spectroscopy System Intrinsic Germanium As per the Technical Specifications 2 412' CB Spectroscopy system with low-level shield; used primarily for effluent sample analysis. Liquid Scintillation
-- As per th e Technical Specifications 1 412' CB Used for tritium determination in water, air (freeze out or gel), and urine.
Shielded GM Counting System GM 200 dpm 2 412' CB High-level sample counting; backup for low background system. Laboratory Monitor GM N/A 1 412' CB Check potentially high
-level samples before placing in low
-level system; monitor background in counting room, warn of changes.
RN 99-162 RN 14-034 RN 17-030 12.3-19 Reformatted M ay 2018 TABLE 12.3
-2 (Continued)
FIXED LABORATORY INSTRUMENTATION INSTRUMENT DETECTOR SENSITIVITY (1) NUMBER LOCA TION REMARKS Self-Reading Pocket Dosimeter Charger s N/A N/A 2 Various Used for charging and/or zeroing pocket chamber
-type dosimeters.
Electronic Dosimeter Reader s N/A N/A 2 Used for programming and turning electronic dosimeters on/off. (1) Instruments will be calibrated as part of the counting laboratory quality control program, using NBS
-traceable sources appropriate for each counting system.
RN 99-163 RN 17-030 RN 14-034 12.3-20 Reformatted M ay 2018 TABLE 12.3
-3 PORTABLE HEALTH PHYSICS INSTRUMENTS INSTRUMENT RADIATION DETECTED RANGE ACCURA CY NUMBER (1) LOCATION REMARKS GM Survey Meter beta gamma 0-200 mr/hr 10% full Scale 6 Refer to Section 12.3.2.1.2 Equipped with end window, side window, or pancake probe.
GM Survey Meter gamma 0-1000 R/hr 10% 14 Refer to Section 12.3.2.1.2 Fishing pole type with extendable probe; 20 in to 13 ft.
GM Survey Meter
-Friskers beta gamma 0-50,000 cpm 10% 50 Refer to Section 12.3.2.1.2 Primarily personnel monitoring usage.
GM Survey Meter
-Remote Monitoring Gamma gamma 0-1000 mr/hr 10% full scale 13 Refer to Section 12.3.2.1.2 Provide remote area monitoring capability.
Ionization Survey Meter beta gamma 0-5000 mr/hr 10% full Scale 33 Refer to Section 12.3.2.1.2 Air ionization chamber.
High Range Survey Meter beta gamma 0.1-500 R/hr 10% full Scale 1 Refer to Section 12.3.2.1.2 Air ionization chamber.
Neutron Rem Counter thermal through fast neutrons 0-5 Rem/hr 10% full Scale 3 Refer to Section 12.3.2.1.2 A BF 3 , helium or equivalent tube inside a moderator for detection of neutrons up to 10 MeV. Scintillation Counter alpha 0-1 M cpm 10% full Scale 1 Refer to Section 12.3.2.1.2 An alpha scintillation crystal covered with a thin mylar window.
Pocket Dosimeter g amma x-ray 0-500 mr 10% 360 Various Pocket Dosimeter gamma x-ray 1500 mr 10% 120 Various R N 9 9-164 12-033 RN 12-033 17-030 RN 17-030 12-033 R N 99-164 12-033 17-030 R N 99-164 14-034 18-016 RN 12-033 R N 99-164 12-033 17-030 RN 14-034 12.3-21 Reformatted M ay 2018 TABLE 12.3
-3 (Continued)
PORTABLE HEALTH PHYSICS INSTRUMENTS INSTRUMENT RADIATION DETECTED RANGE ACCURACY NUMBER (1) LOCATION REMARKS Electronic Dosimeters gamma - 5% 400 Va rious Used for personnel exposure tracking. They are rate and integrating. Number is based on having sufficient in stock to support operational and E-kit needs. Thermoluminescent Dosimeters g amma, beta, neutron - 20% variable Vendor Supplied Used personnel exposure monitoring as dose of legal record. Integrating.
Job Site Air Samplers - - - 14 Various Particulate and iodine sampler; may have extendable sample head (tygon); normally used at job sites for longer or continuous sampling.
Hand Held Air Samplers - - - 17 Various Particulate and iodine sampler; normally used for quick grab samples or short duration jobs.
Tritium Samplers
- - - 2 Various Noble-Gas Samplers
- - - 5 Various ___________________________________
(1) The number of instruments is based on the minimum number that should be in inventory (not necessarily in calibration or in service) to support normal operational needs and in some cases, emergency kits; exceptions are noted in the remarks.
RNs99-164 12-033 14-034 RN 17-030 RN s99-164 14-034 RN 14-034 RN 14-034 12.3-22 Reformatted M ay 2018 TABLE 12.3
-4 RESPIRATORY PROTECTION EQUIPMENT DEDICATED TO
- TYPE QUANTITY Normal Operations and Major Outages Full Face Particulate Respirator.
100 Full Face Continuous Air Flow Respirator.
40 Continuous Air Flow Hood.
6 Self-Contained Breathing Apparatus (30 Min. Air Supply). 10 Emergency Use Full Face Particulate Respirator.
20 Self-Contained Breathing Apparatus (30 Min. Air Supply).
14 Air Supplied Suit or Hood 4 All respiratory devices available for emergency and non
-emergency conditions as required. RN 17-030 NOTE FIGURE 12.3-1 Figure 12.3-1 is being retained for historical purposes per NEI 98-03, Revision 1.Vice PresidentNuclear OperationsGeneral ManagerNuclear Plant OperationsManagerHealth Physics ServicesSupervisorCount RoomSupervisor ALARASupervisorField Operations SupervisorRadwasteStaff Health PhysicistsHealth Physics SpecialistsSupervisorHealth Physics Support ServicesSupervisorRadiological Analytical Services 00-01 00-01 SOUTH CAROLINA ELECTRIC & GAS CO, VIRGIL C. SUMMER NUCLEAR STATION Amendment 00-01 Decmeber 2000 Health Physics Organization Chart Figure 12.3-1