ML20039C736
| ML20039C736 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/21/1981 |
| From: | BECHTEL GROUP, INC. |
| To: | |
| Shared Package | |
| ML20039C723 | List: |
| References | |
| 13587-2-N01-100, 13587-2-N1-100, NUDOCS 8112300095 | |
| Download: ML20039C736 (12) | |
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Design Criteria 13587-2-N01-200 GPU SERVICE CORPOR." TION THREE MILE ISLAND - UNIT 2 RECOVERY FACILITIES DESIGN CRITERIA DOCUMENTS COVER SHEET 13587
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?A DESIGN CRITERI A DOCUMENTS DISCIFLINE E
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Dosign Criteria 13587-2-N01-100 h
SHIELDING DESIGN AND ACCESS CONTROL DESIGN CRITERIA TABLE OF CONTENTS PAGE 1.0 GENERAL 1
2.0 GUIDELINES FOR GENERAL ARRANGEMENT AND SHIELDING 2
3.0 SOURCE TERMS 3
4.0 ACCESS CONTROL AND RADIATION ZONING 4
5.0 AREA RADIATION AND AIRBORNE RADI0 ACTIVITY MONITORING 6
6.0 DELETED 7
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- 1. 0 GENERAL 1.1 The primary objective of the shielding design and access control will be to protect operating personnel and the general public from potential radiation sources in the reactor, power conversion system,
-radwaste system, and other auxiliary systems, including associated equipment and piping. Shielding will be designed to perform the fol-lowing functions:
a.
Limit the dose to plant personnel, construction workers, vendors, and visitors during cleanup, recovery, and inspection to within the requirements of 10 CFR Part 20 and to meet the intent of Regulatory Guide 8.8.
b.
Limit the dose to unit personnel to within the requirements of 10 CFR Part 50, Appendix A, Criterion 61, Fuel Storage and Handling and Radioactivity Control.
c.
Limit the dose rate to certain components in high-radiation areas within specified radiation tolerances.
d.
Limit dose to persons at the boundary of the restricted area, due to direct radiation during normal operation, to a value no greater than 10 CFR Part 20 limits.
e.
Limit dose to persons at the site boundary due to direct
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radiation during normal operation to a value less than
- 0 CFR Part 190 limits.
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D; sign Critsria 13587-2-N01-100 2.0 GUIDELINES FOR GENERAL ARRANGEMENT AND SHIELDING 2.1 The following guidelines will be used for equipment layout and shielding of the plant.
These guidelines will be used as the design basis for initial shielding design, such as determination of shield wall thickness, materials, and locations. As the detailed facility design develops, an ALARA review of the facility will be made.
This review may result in the inclusion of additional permanent or temporary shielding in excess of that indi-cated by the design criteria in order to achieve a fully acceptable design from an ALARA standpoint.
All systems containing radiaactivity will be identified and shielded, based on the access requirements of the area. All areas within the Owner-controlled area will be divided into zones, with dose rate levels and anticipated access a shown in the following table based on source terms for normal operation.
TABLE 1 RADIATION ZONES ZONE DESIGN DOSE RATE ACCESS DESCRIPTION (MREM PER HR)
U' controlled, Unlimited Access I
50.5 (Note 1) n II 0.5-2.5 Controlled, Limited Access 40 Hrs Per Week III 2.5-25 Controlled, Limited Access 4 to 40 Hrs / Week IV 25-100 Controlled, Limited Access 1 to 4 Hrs / Week V
100-1000 Normally Inaccessible Access During Emer-gency VI 1000-3000 Normally Inaccessible Access During Emer-gency Locked Barrier to Zone VII 23000 Normally Inaccessible Access During Emer-gency Locked Barrier to Zone NbTE 1: Design dose rates in office spaces and other Zone I areas which are continuously occupied eight hours per day, five days a week or more, shall be less than 0.25 mrem /hr.
Corridors and other Zone I areas of a transient occupancy nature shall be below 0.5 mrem /hr.
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Drsign Criteria 13587-2-N01-100 h
3.0 SOURCE TERMS 3.1 During the initial containment decontaminm. ton effort, solid, liquid, and airborne activities will have to bs monitored. Direct radiation sources will be from contamination plateout on all such sur-faces, the reactor coolant system, fuel, and equipment. The sources involving different isotopes will be divided into six energy bins cor-responding to the next highest gamma energies of 0.4, 0.8, 1.3, 1.7, 2.2, and 2.8 Mev. The contribution from individual sources will be calculated based on the model described below. The total dose to the receptor sill be taken as the sum of the doses from each source.
3.2 The geometric model assumed for shielding evaluation of tanks, heat exchangers, filters, demineralizers, and evaporators will be'a finite cylinder source and for piping, an infinite shielded cylinder.
Corrosion products deposited on the surfaces such as pipe will be treated as a cylinder surface source. The mathematical models will be based on the formulations in:
a.
Reactor Shielding Design Manual, edited by Th. Rockwell III, first edition, Van Nostrand, New York, 1956.
b.
Engineering Compendium on Radiation Shielding, edited by R. G. Jaeger, E. P. Blizard, A. B. Chilton, M. Grothenhuis, A. Honig, T. A. Jaeger, and H. H. Eisenlohr, Springer-Verlag, New York, 1968.
Various technical papers on buildup factors.
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Design Criteria 13587-2-N01-100 h
4.0 ACCESS CONTROL AND RADIATION ZONING 4.1 Access to areas inside the plant structures and plant yards is regulated and controlled by radiation zoning and access control.
Each radiation zone defines the radiation level range to which the aggregate of all contributing sources must be attenuated by shielding.
4.2 All plant areas are categorized into radiation ;ones according to expected radiation levels and anticipated perr,onnel occupancy with consideration given to-maintaining personnel exposures as low as rea-sonably achievable and within the standards of 10 CFR 20. Each room, corridor, and pipeway of every plant building is evaluated for potential radiation sources during clean-up operations for maintenance occupancy requirements; for general access requirements; and for material exposure limits te determine appropriate zoning.
Radiation zone categories employed and their descriptions are given in Table 1.
All frequently accessed areas, e.g., corridors, are shielded for Zone I or Zone II access.
The control of ingress or egress of plant operating personnel to con-trolled access areas and procedures is employed to assure that radiation levels and allowable working times are within the limits prescribed by 10 CFR 20.
Whenever practicable, the measured radiation level and the location of the source are posted at the entry to any radiation or high radiation area.
4.3 The access zones for each area will be determined based upon the radioactive sources, process equipment to be shielded, adjacent zone re-quirements, and maintenance requirements.
Efforts will be made to locate processing systems in such a manner as to minimize exposure to plant personnel.
Plastic tents and ventilation hoods will be required over all decontamination tanks to minimize the dispersion of airborne contaminants.
Concrete shield walls will be provided around the decon-tamination and storage areas.
4.4, In the design of the cleanup and recovery facilities, permanent and temporary shielding will be incorporated.
Concrete walls and labyrinths aro used to shield general access areas from high radiation storage or wuce processing rooms. Outside perimeter facility walls will be built b4sei upon shielding calculations. Steel or lead plate may be substituted w3ere necessary in the design of these structures.
4.5 The use of temporary shielding will be required on a case-by-case basis. This will especially be necessary when extremely contaminated equipment is to be prepared for further decontamination. Where possible, transport of equipment within the facility will be done via shielded forklift trucks and monorails. As equipment is removed from the con-tainment, lead blankets or bricks may be arranged around the transfer cart to minimize exposure to working personnel and to minimize the area radiation level. Concrete block can also be used for temporary shielding y
along permanent shield walls in case more shielding is required from Page 4 Rev. 0
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h' time to time. The block can De stacked up around open hatches or door-ways where " shadow" shielding may be necessary. Another temporary shielding method is the use of lead shot bags placed over equip 5cnt or
" hot" pipes where adequate support structures exist.
Entire systems, both old and m, will have to be reviewed to determine whether permanent or temporary snielding is required for maintaining low radiation levels in general work areas. The new facility shield design will be based upon estimation of the maximum radiation sources to be located in the building. A thorough review of waste activities and quantities to be processed in each building will be conducted. Wastes such as spent resins, demineralizer beds, compacted trash, and evaporator bottoms have to be considered.
The main facilities to be reviewed are the waste staging area, equipment decontamination building, containment recovery service building, and any new solidification systems.
Upon reentry into the containment, major areas ~uf interest will be surveyed to establish allowable working periods. The initial dose rates are expected to range from 1.0R/hr. to 10.0R/hr. depending on the location inside the containment vessel (excluding the reactor cavity). Areas such as the floor hatch at the 305' level, air coolers, and the top of the steam generator compartments may have to be temporarily shielded.
As decontamination proceeds and the general area radiation levels decrease, relative " hot spots" will be identified and be either removed or shielded by lead blankets, concrete block, or other shielding techniques.
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The shielding criteria and design in the auxiliary building is based on
.the shielding of processing equipment, resin tanks and the transfer of spent resins and solidified waste. Because of the high initial radio-active levels of the liquid to be processed, additional shielding may be required. Also the radiation zone designations may have to be re-evaluated during processing of these high level wastes.
The traffic paths for the removal of the spent resins and filter cartridges may have to be roped off during transfer to the solidification processing area.
. aste stariTg facilities will be provided. Very high activity drums may l1 W
require sw temporary shielding. The building walls will be of sufficient thickness so that neither the site boundary nor the protected fence radiation limits will be violated.
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5.0 AREA RADIATION AND AIRBORNE RADIOACTIVITY MONITORING 5.1 Area radiation monitoring is provided to supplement the personnel and area surveying capabilities to ensure compliance with the personnel radiation protection guidelines of 10 CFR 20, 10 CFR 50, 10 CFR 70, and Regulatory Guides 8.2, 8.8, and 8.12.
Gamma radiation detectors will be l1 located throughout the plant.
These monitors will be permanently mounted in general occupancy areas such as Zones I and II.
Portable monitors will be used where the task requires plant personnel to be in areas of mid to high radiation zones.
Airborne particulate activity can be a significant problem during gross decontamination efforts.
5.2 Consistent with this purpose, the area radiation monitors function to:
a.
Immediately alert plant personnel entering or working in non-radiation or low-radiation areas of increasing or abnormally high radiation levels which, if unnoticed, could possibly' result in inadvertent overexposures.
b.
Inform the control room operator of the occurrence and approx-imate location of abnormal radiation increase in non-radiation or low-radiation areas.
c.
Comply with the requireuients of 10 CFR 50 Appendix A, General Design Criterion 63 for monitoring fuel and waste storage and h.
handling areas.
d.
Certain monitors located near the spent fuel pool act as criticality alarm monitors and conform to the requirements of 10 CFR 70 and Regulatory Guide 8.12.
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Check that plug-in, accessible bracket-hung, removable units h.
are provided for easy removal and relamping outside high radia-tion areas.
(Lightweight units are preferable for ease of
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handling.)
e.
Check that extension cord powered units stored on brackets and cord hangers outside the entrance are provided if permanent l
units are not practical, and that pre placed brackets are provided with the high radiation area to facilitate installation.
6.6.2 Contamination Control and Coatings a.
Check that floor drains and properly sicped floors are provided for each room or cubicle containing serviceable components with radiation levels of a Zone III or higher.
b.
Check that local gas traps or porous seals are not used on floor drains from radiation areas.
c.
Check that gas traps are provided at the common sump or collec-tion tank.
d.
Check that concrete surfaces in areas of potential contam-ination are covered with a smooth-surfaced coating for the floor and wainscot which will allow easy decontamination.
Ci' e.
Check that threshold curbs, cofferdams, or other means are w-provided to control radioactive leakage or spills.
f.
Check that protection from back flooding of floor drains is provided.
6.6.3 Access Platforms a.
Check that equipment subject to routine maintenance (defined as at least once per year) have permanent access platforms.
b.
Check that direct access to active components is provided from any working platform.
c.
Check that ample space is provided on platforms for accom-modating safe personnel movement during replacement of com-ponents (including the use of any necessary material handling equipment).
6.6.4 Remote Viewing Devices Check that in high radiation areas (Zone V and greater) where routine visual surveillance inspections are required remote, viewing devices are provided.
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6.6.5 Temporary Shielding Check that when shielding is required and permanent shielding is not feasible sufficient space and supports for portable shielding are pro-vided and the structure is capable of accepting the additional loading.
6.6.6 Insulation Check that piping and components requiring frequent (once per year or greater) access for maintenance, inspection, etc. utilize quick removal insulation wherever practical.
6.6.7 Plant Services Check that services such as electrical power, water, respirable air, and compressed air are available reasonably close to radiation work areas.
TABLE 2 TYPICAL RADI0 ACTIVE PIPING CLASSIFICATION AND ROUTING Exposure Rate at Acceptable (I)
Contact with Pipe Radioactivity Radiation Zone Surface (mr/hr)
Description Routing C-Non-radioactive I, II, III, IV, V 50.5 Slightly radioactive I, II, III, IV, V 52.5 Low radioactivity II, III, IV, V 525 Low to moderately III, IV, V radioactive
$100 Moderately radioactive IV, V 2100 Highly radioactive V only(2)
(1) The routing of non-radioactive or low radioactivity piping in high radiation zones should be minimized.
(2) Piping from other Zones should be minimized in Zones VI and VII.
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