1、ASHRAE DG-L 73 0757b50 050bL00 073 I d Heating, Ventilating, and Air-Conditioning DESIGN GUIDE DEPARTMENT OF ENERGY NUCLEAR FACILITIES American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. ASHRAE DG-L 93 0759b50 050bLOL T2T I Heating, Ventilafng, and Air-Conditioning DESIGN
2、 GUIDE for DEPARTMENT OF ENERGY NUCLEAR FACILITIES ASHRAE DG-I, 73 m 0759650 0506202 966 I Heating, Ventilating, and Air-Conditioning DESIGN GUIDE for DEPARTMENT OF ENERGY NUCLEAR FACILITIES American Society of Heating, Refrigerating and Air-conditioning Engineers, Inc. ASHRAE DG-L 73 0759b50 050bL0
3、3 AT2 I ISBN 1-88341 3-03-6 Copyright 1993 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. 1791 Tullie Circle N.E. Atlanta, GA 30329-2305 Printed in the United States of America iv ASHRAE DG-L 93 0759b50 05ObLOY 739 I TABLE OF CONTENTS Sectionflitle Page Foreword vii
4、1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Confinement System Classification 1 Confinement System Differential Pressures . 5 Air Lock Design 8 System Monitoring Capability . 14 Pitot Tube Test Ports . 20 Nuclear Facility Air Change Requirements . 24 Glovebox Fire Suppression . 27 Filter Selection . 28 Redu
5、ndancy Requirements 32 Control Systems 34 Pressure Gauge Installation . 39 Glovebox Airflow Instrumentation . 46 Enclosure Face Velocity Requirements 53 Fire/Smoke Protection of HEPA Filters . 56 Glovebox Ventilation Design 64 V ASHRAE DG-L 73 0757650 0506105 h75 I FOREWORD The purpose of the Heatin
6、g, Ventilating, and Air-Conditioning WAC) Design Guide for Department of Energy POE) Nuclear Facilities is to help ensure consistency in establishing the design basis for HVAC systems serving such facilities. Any design for DOE facilities must fulfill the requirements stated in DOE Order 6430.1 A, G
7、eneral Design Criteria. However, the order references many documents, such as ERDA 76-21, Nuclear Air Cleaning Handbook; NRC Regulatory Guides; and the ACGIH Industrial Ventilation Manual. Order 6430.lA also has many void areas with respect to HVAC design that have generated confusion and inconsiste
8、nt application of sound HVAC principles. This design guide is a document that combines applicable information from all of these resources to provide HVAC guidance for the design engineer. The intent of this document is to not only state the Department of Energys design requirements for HVAC systems,
9、 but also to express some of the engineering judgment used in designing the systems. This design guide was developed by members of ASHRAE TC 9.2, Industrial Air Conditioning, Subcommittee on Nuclear Facilities. The information in each section was obtained from researching DOE orders, technical docum
10、ents, and site procedures and from discussions with experienced personnel at DOE sites. This document should be used by design agencies, liaison groups, health protection organizations, and other persons or groups involved in the design, installation, and operation of HVAC systems. The use of this d
11、ocument is most effective when preparing design criteria for a project. By incorporating the appropriate sections of this design guide in this phase, the document can provide the design agency with appropriate HVAC system design parameters that will fulfill the needs of the customer and satisfy code
12、 and regulatory requirements. Although this document is considered a design guide, it should be understood that the information presented reflects both the current DOE requirements and the generally accepted requirements with respect to HVAC. However, the responsibility for satisfying applicable cod
13、es and regulations remains with the designer. All new project installations and future modifications should consider these design guidelines. vii ASHRAE DG-2 93 0757b50 05ObLOb 502 I SECTION 1 CONFINEMENT SYSTEM CLASSIFICATION GENERAL HVAC systems in nuclear facilities must be designed to confine tr
14、ansferable radioactive contamination within specific controlled building areas in the event of an accidental release, spill, or system failure. As required by DOE Order 6430.1A, three confinement systems are used to achieve this objective: primary confinement, secondary confinement, and tertiary con
15、finement. Before any HVAC system design can begin, the building areas must be analyzed on a case- by-case basis to determine the ventilation system requirements for the confine- ment. Using ERDA 76-21, Nuclear Air Cleaning Handbook, as a guide is very helpful. With the guidance of the Handbook, conf
16、inement areas, called zones, must be established throughout the building based on the level of hazard in the areas. The zone classification determines the ventilation and architectural requirements that the confinement system) must meet. After the zones have been established, the ventilation system
17、is designed to maintain a prescribed differential pressure between various zones. CONFINEMENT SYSTEM DEFINITIONS The following confinement system descriptions are typical for a plutonium facility confinement system and conform to DOE Order 6430.1A. The order also contains confinement system descript
18、ions for specific facilities, such as tritium facilities. At least one of the confinements must be designed to withstand design- basis accidents, such as a tornado. This is normally documented in the facilitys safety analysis report (SAR). Primary Confinement The primary confinement system consists
19、of barriers, enclosures, gloveboxes, piping, vessels, tanks, glovebox exhaust ductwork, primary confinement HEPA filter plenums, etc., whose principal function is to prevent the release of hazardous material to areas other than where process operations are normally 1 ASHRAE DG-L 73 m 0757650 0506307
20、 448 I conducted. Unavoidable breaches in the primary confinement barrier must be compensated for by provision of adequate inflow of air or safe collection of spilled material. The exhaust ventilation system must be sized to ensure adequate inflow of air in the event of the largest credible breach o
21、f confinement. This level of confinement is used when radioactive materials or contamination is present during normal operations. Secondary Confinement The secondary confinement system consists of the walls, floors, roofs, and associated ventilation systems that confine any potential release of haza
22、rdous materials from primary confinement. This system typically includes the operating area boundary and the ventilation system serving the operating area. The ventilation system is designed to ensure proper airflow direction and velocity in the event of the largest credible breach in the barrier. P
23、enetrations of the secondary confinement barrier typically require positive seals to prevent migration of contamination out of the secondary confinement area. This level of confinement is used when a space could become contaminated from an abnormal event. Tertiary Confinement The tertiary confinemen
24、t consists of the walls, floor, roof, and associated exhaust system of the process facility. It is the final barrier to release of hazardous material to the environment. This level of confinement is used when a space is never expected to become contaminated. CONFINEMENT SYSTEM CLASSIFICATION To dete
25、rmine the ventilation requirements for each confinement system, each area in the facility must be analyzed with respect to the types of hazards. Each hazard is analyzed for each zone, and the zone is classified based on the worst- case hazard. It is critical that past operational experience be consi
26、dered along with this information in the zone classification process. Consultation with the responsible health protection organization is essential. Contamination Confinement system classification based on transferable contamination levels is defined as follows: 2 ASHRAE DG-1 93 0759b50 OSObLOB 384
27、I Primary ConJinement formerly Zone 1): Transferable and airborne con- tamination levels are assumed to be present and may be very high, such as airborne contamination levels greater than 100 X DAC (derived air concentration per DOE 5480.1 l), and present serious problems for secondary and tertiary
28、confinement regions should contamination migration occur. Such areas are not normally occupied. Examples include canyons, reactor rooms, pin rooms, remotely operated cells, gloveboxes, etc. Secondary Confinement formerly Zones 2 however, it reduces the chance of all air lock doors between building z
29、ones being opened simultaneously. The use of multichamber air locks is also recommended where building spaces operating at different pressure differentials are supported by the same air lock, as exhibited in Figure 3-2. Multichamber air locks are excellent for maintaining building zone pressure diff
30、erentials at low total airflows. The multichamber air lock should be designed with the same considerations as a single-chamber air lock. A safeguard that should be considered for each air lock design and installation is a differential pressure monitoring system. The system monitors the differential
31、pressure between the building zones and the air lock and the overall differential pressure between the building zones. The monitoring system should have a low pressure differential setpoint, which would activate a visual and Primary Confinement Zone P=-o.SO wg Qgure 3-2 Secondary Confinement Zone P=
32、-o.15“ wg U Secondary Confinement Zone P=-o.20“ wg Tertiary Confinement Zone P=-o.OS wg Multichamber air lock serving zones with diflerent pressures. 11 ASHRAE DG-L 73 m 0757b50 050bLL7 377 I audible alarm. The alarm would warn building personnel of the low pressure differential condition where a po
33、ssible airflow reversal could occur. The alarm would also inform the appropriate building personnel of a possible problem in the ventilation system. An example of an air lock incorporating all of the features mentioned above is shown in Figure 3-3. AIR LOCK APPLICATION DOE Order 6430.1A states that
34、air locks shall be considered for access through confinement barriers. The application and design of an air lock is dependent upon the location of the air lock within the facility, the contamination potential of the areas on either side of the air lock, and the radiotoxicity of the contaminants that
35、 may be present. For example, air lock design requirements between secondary and tertiary confinement areas can be less conservative than Tubing Undercut (max.) LOW Setpolnt Alarm figure 3-3 Air lock incorporting recommended design features. 12 ASHRAE DG-1 93 m 0757b50 050b1LB 223 I air locks betwee
36、n primary and secondary areas. Also, the design of air locks for a plutonium finishing area, for example, must be much more conservative than the requirements for fission product or induced radionuclide processing areas. Although testing has shown that the combined ventilation air method is the most
37、 effective ventilation design for air locks, it may not be appropriate in all situations. The design engineer must also consider the operational use of the air lock during design. Frequently, air locks are used as 44jumping off points into highly contaminated process areas for maintenance, decontami
38、nation, etc. Breathing air stations are sometimes located in such air locks for air-supplied hoodhit “hook-up.” During the operation, the air lock can become highly contaminated when outer layers of protective clothing are removed in the air lock with one or both of the air lock doors open. In such
39、applications, the air lock design should be rather simple. It should include louvered doors on both ends of the air lock with a continuous sweep of air from the area of low (or no) contamination potential to the area of higher contamination potential. No dedicated air supply is needed. Historically,
40、 these types of air locks have been employed and have served their purpose. REFERENCES 1. Allen, B.M., Jr., R.E. Perry, and K.R. Scaggs. 1989. Nuclear facility air 2. Savannah River Site process ventilation design guide, Savannah River Site, lock design criteria. ASHRAE Transactions 95(2). SC, DPSPM
41、-GEN-101, Rev. 2, September 1990. 13 ASHRAE DG-1 73 0757b50 050b117 1bT SECTION 4 SYSTEM MONITORING CAPABILITY GENERAL The health and safety of plant personnel and local residents depend in part upon the confinement of contamination within the primary confinement system (see DOE 6430.1A, 1300-7.2, f
42、or definition) of the process facility. It is mandatory that ventilation systems have adequate system monitoring capability in order to accomplish this objective. Otherwise, it is difficult to identify upset conditions and/or gradual deterioration in system performance. It provides the tools that th
43、e building custodian and maintenance and air balance personnel need to monitor, troubleshoot, repair, and adjust the ventilation system. Permanently installed instrumentation, which monitors system performance, greatly reduces the time required to identify and correct air balance problems. DOE Order
44、 6430. lA, Section 1550-99.0.1, states, “Adequate instrumentation and controls shall be provided to assess ventilation or off-gas system performance and allow the necessary control of system operation.” INSTRUMENTATION Following is a description of the various types of instrumentation used to monito
45、r the ventilation system, the function and application of each type, and the design criteria that should be followed to ensure maximum instrumentation utility. Pressure Instrumentation Numerous methods are used to measure static, velocity, and differential pressures in a ventilation system and the f
46、acility it serves. Typical devices used include static pressure tips, pitot tubes, manometers, and diaphragm pressure gauges. These instruments should be used to measure static pressures in the main and major branch ducts of the system. They should also be used to measure differential pressures acro
47、ss filters, air locks, and confinement barriers in the facility. Differential pressure measurement between facility confinements include differential pressure measured between a glovebox (or process cabinet) and the 14 room in which it is installed. All new (or modified) ventilation systems should b
48、e equipped with instrumentation that measures the static and differential pressures needed to operate and repair the system and to maintain the facility air balance. New facilities should be equipped with an atmospheric static pressure reference header so all duct static pressure instrumentation can
49、 be referenced to a common atmospheric pressure. The atmospheric pressure sensor should be protected from wind effects. Multiple sensors tend to be more stable in application. Pressure data are often transmitted to system control instrumentation or to data loggers. Whenever a pressure is transmitted, install a local pressure gauge (or manometer) to provide local pressure monitoring and easy confirmation of calibration. All local gauges and transmitters must be equipped with valves and connectors to permit isolation, venting, and calibration (see Section 11). The monitoring system sho
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