Regulatory Guide 3.20
| ML003740115 | |
| Person / Time | |
|---|---|
| Issue date: | 02/28/1974 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| References | |
| RG-3.20 | |
| Download: ML003740115 (3) | |
Febr.wry 197A
U.S. ATOMIC ENERGY COMMISSION
REGULATORY GUIDE
DIRECTORATE Of REGULATORY
STANDARDS
REGULATORY GUIDE 3.20
FUEL REPROCESSING PLANTS
PROCESS OFFOAS SYSTEMS FOR
offgas systems are gas collection systems, condensate chemical monitoring
A. INTRODUCTION
removal systems, sampling and systems.
systems, and control and instrumentation of Section 50.34 of 10 CFR Part SO, "Licensing located within requires, among Process offgas systems are generally Production and Utilization Facilities" prevent uncontrolled a construction building structures designed to other things, that each applicant forfacility, including release of radioactive materials portions of offgas under postulated permit for a production or utilization those principal design accident conditions. Although fuel reprocessing plants, include the systems so located do not require designs which (f) "Environmental criteria for the facility. Paragraph Applications for duplicate this capability to withstand postulated Report," of §50.30. "Filing of be designed to work requires that an accidents, offgas systems should systems) and Licenses; Oath or Affirmation,' (confinement or operating with building structures application for a construction permit by building ventilation systems to prevent uncontrolled be accompanied license for a fuel relkocessin - plant D, "Interim releases of radioactive material.
Those portions of offgas an Environmental Report. Appendix Procedure: systems not enclosed in protective structures should Statiment of General Policy and against failures which could Policy themselves be designed Implementation of the National EnvironmentalPart SO cause uncontrolled release of radioactive materials under to 10 CFR
Act of 1969 (Public Law91-190)"' those loads attributable requires, among other things, that the Environmuital al normal operating loads plus phenomena such as earthquakes and discussion of the status of compliance to natural criteria. Accident Report include a in the design with applicable environmental quality tornadoes postulated equipment and of the facility should also include regulatory guide conditions postulated standards and requirements. This principal utility failures and failures due to engineering or provides information relative to establishing design criteria for equipment associated with process opetating errors.
plants.
offgas treatment systems for fuel reprocessing postulated accident To meet reliability needs during
B. DISCUSSION
are generally equipped with conditions, offgas systems to maintain critical dissolver duplicate equipment items designed and Process offgas systems, i.e., vessel and functions, e4g., installed spare exhaust blowers are designed to confine hazardous switch to emergency offgas systems during process equipment that will automatically chemical or radioactive materials evolved loss of prime utility source to waste storage and to reduce utility systems upon operations and radioactive assure offgas flow.
gaseous process effluents to levels their concentrationsIf of process as low as practicable. I Usual constituents Energy Commission treating equipment are On November 1. 1973, the Atomic Collection lines and offgas and decontamination Register (38 FR 30203) proposed exposed to cell atmospheres published in theitsFederal which would place the provisiom fluids. To assure system amendments to regulations into a now Part SI to be solutions as well as the collected of Appendix D. to 10 CFR Part SO Policy used in lines and equipment and Procedures for reliability, the materials to heat and the entitled "Ucensirt and Regulatory must be nonflammable, resistant Environmental Protection." gases and the strong corrosive effects of the collected as stated in 10 CM chemicals used for equipment decontamination.
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Staiiesa steel is usually employed for Process lines Vessels, rather than plastics, a radiation, fire, or thermal damage, which may be subject no Coordination of designs for the offgas systems or carbon steel, whi. to with may be subject to corrosive the designs for the confinement systems and building attack by process materi.ch Ventilation systems is important to assure or decontamination solutions.
als complementary functioning of these systems. These systems work together to keep process vessel pressures Offgas systems function and noncondensable gasesto handle both condensab lower than pressures in surrounding process areas operations and waste storage. generated in proce le thereby limiting leakage of contaminated gases into The condensab' st process cells and thence into component of the offgas consists primarily of steam anle potentially inhabited plant areas.
water vapor. To minimize the load on the offgas systea and to increase the operations, condensableseffectiveness of offgas deanu n a
C. REGULATORY POSITION
are generally removed from offgas stream by condensers th recycled to the process as water. and stack drains and the pe 1. All parts of the process offgas system should be in excess of process needs Amounts of condensat,n designed:
may waste to surface waters or revaporized be discharged as liquic the atmosphere. The choice and discharged tc a. To limit the release of radioactive materials of discharge mode for excesi condensables is generally determined during normal operation to the levels stated in 10 CFR
as meteorology, hydrology, by site factors such Part 20.
and of the mode of discharge, sampling demography. Regardless b. To limit the release of noxious and monitoring of all materials to effluents is necessary to comply with Federal and State statutes and operation and compliance assure effective process implementing regulations imposed by Federal, State, and with regulations concerning regional agencies.
release of these effluents.
c. To withstand postulated accident conditions to Offases are further treated the extent that uncontrolled release of radioactive by one or more mass material to the environs is prevented or to be enclosed transfer devices, as necessary, to meet release limits for within a structure designed both radioactive and noxious accident conditions to the to withstand postulated often include caustic scrubbers, materials. Devices used same extent. Accident conditions postulated should include carbon adsorbers, and zeoliteacid scrubbers, activated tornado, equipment and utility failure, earthquake.
iodine, and water scrubbers adsorbers to remove or operating error. The pertinent and engineering nitrogen. Perfomiance data to remove oxides of quality assurance for these devices have been requirements of Appendix B to
10 CFR Part 50 should published. 3 be applied to all activities affecting the safety-related functions of these structures, systems, and components.
Particulate removal equipment d With adequate duplicate process and support efficiency is needed to satisfactorily with high collection equipment to maintain system safety functions in the discharge to the environs. clean gases prior to event of any single failure or during maintenance Various types of filters are operations.
usually used in this service.
operation, such filters should To assure reliable process e. To resist fire, thermal, effects, preceded in the process be resistant to fire or be and the corrosive train by fire-suppressing effects of cel atmospheres, decontamination equipment. Filters and adsorbents solutions, such as zeolites can be and collected gases to the extent necessary to maintain damaged by liquids in the safety-related functions.
damage, filters and adsorbers offgas. To prevent such heater! or by electrical or may be preceded by f. To permit inspection, maintenance.
maintain the offgas above its steam traced lines which of systems and components and testing Lthat have safety-related
"Design, Construction and dewplxint. ORNL-NSIC.65, functions to assure their continued Testing of High.Efficiency functioning for the Air Filtration Systems for Nuclear life of the facility.
a comprehensv review Of Application," 4 offers document is not a standard a*
f filtration system. This 2. The gas collection equipment should but a guide which suggsts be designed to:
several design alternative a. Collect gases near points of generation and conduct them in closed piping systems to treatment
""Aqueous Processing of systems for the removal of hazardous chemical Ahsessaidast and Expaheuineta LMFBR Fuels-Technkg radioactive materials. or USAEC report ORNL4436, Program Definition." pp. 167-186. b. Operate at negative Oak Ridge National Laboratory, pressures relative to Jwu. 1970. surrounding cells where practical.
4
"C. A. Burchated and A. D. Fuller,
c. Prevent header
"Design. Construction flooding and unsafe and Testing o High-Effclency Nuclear Application." Air Filtration Systems for accumultion of fissionable materials by sloping ORNL-NSIC.-, Oak Ridge National collection piping to drain to appropriate Laboratory. January 1970. process by use of condensers and knockout pots, and by vessels, vessel overflow line
s. use of
3.20-2
d. Minimize entrainment into collection headers, 5. The exhaust equipment should be designed:
thereby preventing unsafe accumulation of fissionable
> materials, by sizing vessel offgas lines to provide low gas a. To provide motive power adequate to overcome velocities, by providing deentrainment devices, and by offgas system head and maintain prescribed offgas separating vessel offgas lines from other vessel lines such system pressures to prevent backflow of contaminated as those receiving jet or pump discharge streams. gases into potentially inhabited areas.
e. Limit spread of contamination by preventing b. With emergency utilities piovided automatically backflows from radioactive to less radioactive areas by on failure of prime utility source.
use of liquid seals on cold chemical addition lines, by providing top entry of offgas branch lines into headers, and by providing pressure-relief devices to guard against 6. The sampling and chemical monitoring equipment pressure increases due to flow blockages or gas flows In should provide:
excess of design specifications.
f. Minimize radiation exposure to plant personnel a. Sampling points for offgas on each chemical by locating process piping containing radioactive removal device and at the process offgas system inlet and material away from areas frequently occupied by plant discharge points.
personnel or by providing local biological shielding. b. Ports for testing filter efficiency on each safety-related stage of filtration.
3. The chemical treatment equipment should be c. Redundant continuous monitoring devices designed to: adequate to measure and record overall effluent radioactivity and system performance at point of process a. Remove both radioactive and noxious gaseous offgas system discharge to the environs. These devices contaminants predictably and effectively from process may be stack monitors which monitor combined plant offgases. These contaminants include iodine, organic and discharges.
Inorganic iodine species, and other hazardous materials. d. Alarms in a continuously occupied control b. Provide protection to zeolite adsorbers against room to indicate safety-related abnormal conditions.
moisture damage.
4. The particulate removal equipment should be 7. Control and instrumentation systems should be designed to: designed to:
a. Remove radioactive particulate contaminants a. Control automatically or facilitate manual predictably and effectively from process offgas. control of all safety-related process parameters.
b. Resist fire and be located downstream from b. Indicate or record al safety-related process fire-suppressing process devices or be equipped with fire parameters in a regularly occupied control room.
detection and extinguishing devices. Fire-suppressing Parameters include such items as fluid levels, pressures, devices may consist of other process units, such as wet temperatures, and radiation levels.
scrubbers used for chemical treatment, or may be c . Alarm all abnormal safety-related parameters in systems designed specifically for fire protection. a continuously occupied control room.
c. Resist or be protected from condensate damage d. Switch in safety-related standby process devices by maintaining system temperatures above the dewpoint automatically when needed.
of the gas and by providing low-point traps and drains e. Switch safety-related process devices to standby on supply headers. power supplies automatically when needed.
3.20-3