CRSC · California Referenced Standards Code
How must radiation shielding barriers demonstrate compliance?
The CRSC does not set barrier thicknesses itself — it requires that all shielding be designed and documented using the specified NCRP reports (Reports 35, 49, 51) and that any variance come from the Department of Health Services; you must submit shielding calculations and drawings using the appropriate NCRP methodology to demonstrate compliance.
Last reviewed: July 6, 2026
What the code requires — 2-4 sentences
All radiation shielding barriers in rooms and enclosures that house radiation machines must comply with the mandatory standards and appendices in the specified National Council on Radiation Protection and Measurements (NCRP) reports. This requirement is set out in § 3102C (which directs users to the referenced-standard) and § 12-31C-101 (which identifies the specific NCRP reports to be used) . The Department of Health Services is the only agency that may grant a variance or exception to those standards under § 3102C .
All shielding must be designed and documented to meet the mandatory NCRP standards called out by the CRSC; the CRSC itself requires compliance with those reports rather than publishing alternate numeric thicknesses or methods. (See § 12-31C-101 and § 3102C.)
Requirements in detail
Core rule (what you must do)
- Follow the mandatory standards and appendices in the NCRP documents named by the California Referenced Standards Code. The CRSC text requires that: use Report No. 35 (“Dental X‑RAY Protection”), Report No. 49 (“Structural Shielding Design and Evaluation for Medical use of X‑rays and Gamma Rays of Energies up to 10 MeV”), and Report No. 51 (“Radiation Protection Design Guidelines for 0.1–100 MeV Particle Accelerator Facilities”) as the design and evaluation references for shielding design. This direction is the text of § 12-31C-101 .
- Ensure every barrier in rooms/enclosures housing radiation machines meets those NCRP standards: that is the requirement stated in § 3102C of Chapter 31C .
- Any variance or exception to those referenced standards may be granted only by the Department of Health Services as stated in § 3102C .
What the CRSC itself provides (and what it does not)
- Provides: a mandatory cross-reference to the three NCRP reports and a variance rule (see § 12-31C-101 and § 3102C) .
- Does NOT provide: prescriptive barrier thicknesses, step‑by‑step calculation formulas, or numeric occupancy/dose limits in the text of these two sections. Those technical design values and methods are found inside the NCRP reports the CRSC mandates. If you need numeric attenuation values or calculation methods, you must consult the referenced NCRP report specified by § 12-31C-101 .
Decision table — which reference to use
| Equipment / application | NCRP report to use (short name) | Use / scope | Code reference |
|---|---|---|---|
| Dental X‑ray installations | Report No. 35 — “Dental X‑RAY Protection” | Dental operatory shielding and related dental equipment protections | § 12-31C-101 |
| Medical diagnostic and therapeutic X‑ray (energies ≤ 10 MeV) | Report No. 49 — “Structural Shielding Design and Evaluation…” | Structural shielding design for medical X‑ray/gamma installations (typical radiography, fluoroscopy, CT, therapy up to 10 MeV scope in Report 49) | § 12-31C-101 |
| Particle accelerators (0.1–100 MeV) | Report No. 51 — “Radiation Protection Design Guidelines for 0.1–100 MeV Particle Accelerator Facilities” | Shielding design and layout for accelerator facilities, beam lines, and associated enclosures | § 12-31C-101 |
(Again: the CRSC names these reports and makes them mandatory; the technical content you must apply — formulas, attenuation tables, workload/usage assumptions, dose limits — are inside those reports, not in the CRSC text itself.)
Documentation and submittals (what the code expects you to show)
The CRSC requires you to use the referenced NCRP reports. Although § 3102C and § 12-31C-101 do not itemize a submittal checklist, customary and accepted practice to demonstrate compliance (consistent with the CRSC requirement to follow the referenced standards) includes:
- A shielding calculation (showing inputs and results) performed using the appropriate NCRP report/method.
- A statement identifying which NCRP report and which appendices were used.
- Drawings that show barrier locations, material types, and barrier extents.
- If applicable, a copy of the physicist’s report or certifying documentation used to size barriers.
Note: the CRSC text itself directs use of the NCRP standards but does not prescribe the format of submittal. For specific required submittal elements consult the enforcing authority's intake checklist or the NCRP report guidance (not reproduced in § 12-31C-101 or § 3102C) .
Exceptions & special cases
- Variances/exceptions: only the Department of Health Services may grant a variance to the referenced standards — this is explicitly stated in § 3102C .
- Equipment-specific requirements: the CRSC directs you to different NCRP reports depending on equipment energy/type (see the decision table above). The CRSC does not combine or replace the NCRP reports; use the report that matches your machine’s energy and application per § 12-31C-101 .
- If a project includes multiple machine types (e.g., dental and linear accelerator), you must apply the appropriate NCRP report(s) for each machine/space as required by § 12-31C-101 .
If you expect to rely on an alternate methodology or national standard not listed in § 12-31C-101, you must obtain a variance from the Department of Health Services per § 3102C — the CRSC does not authorize local acceptance of other methods by itself .
Common mistakes
- Treating the CRSC as a prescriptive source of thicknesses. The CRSC does not publish thickness tables; it mandates use of NCRP Reports — do not invent or rely on simplified rule‑of‑thumb thicknesses without running the proper NCRP calculations. The CRSC language in § 12-31C-101 makes this mandatory .
- Failing to identify which NCRP report was used. The code requires compliance with those reports; your submission should name which report/appendices were applied (per § 12-31C-101) .
- Assuming local code officials can approve alternate standards without a DHS variance. § 3102C reserves variance authority to the Department of Health Services only .
- Omitting documentation of assumptions (workload, use factor, occupancy factor, distance). While the CRSC calls for use of the NCRP methods, the reports expect these inputs — do not submit a conclusion (barrier thickness) without the underlying assumptions (the CRSC itself expects use of those report methods) .
Worked example — how to apply the rule (process with sample inputs)
Important: the CRSC requires use of the NCRP reports but does not publish the calculation formulas or numeric dose limits. The example below shows the procedural steps you must follow to demonstrate compliance; the final numeric thickness must be calculated using the NCRP method referenced in § 12-31C-101 .
Scenario: You are designing shielding for a small medical diagnostic X‑ray room (conventional radiography/fluoroscopy) whose beam energy is in the range covered by NCRP Report 49.
Confirm applicable referenced standard:
- This is a medical X‑ray installation (energies up to 10 MeV). Use NCRP Report No. 49 as required by § 12-31C-101 .
Gather project inputs (example sample inputs you will document — these numbers are hypothetical and are inputs to the NCRP calculation; they are not code-prescribed values):
- Machine nominal kVp: 120 kVp (documented).
- Workload (mA·min/week): W = 2000 mA·min/week (example).
- Use factor for the wall being sized: U = 0.25 (example).
- Distance from source to point of interest: d = 6.0 m (example).
- Occupancy factor for adjacent area: T = 1.0 (example).
- Permissible design dose (target) — determined from NCRP Report 49 (you must use the report value; CRSC does not restate it) — consult NCRP Report 49 for the design dose limit.
Run the NCRP Report 49 method (steps you must take inside the report):
- Use Report 49 formulas/tables to calculate required barrier transmission given W, U, T, d, and the applicable dose limit.
- Convert required transmission to material thickness using the report’s attenuation coefficients or tables (for example, converting transmission to millimeters of lead or centimeters of concrete per the report methods).
Prepare submittal showing:
- The full calculation with the above inputs and the final computed barrier thickness and material type.
- A clear statement: “Shielding design performed per NCRP Report No. 49 in compliance with § 12-31C-101; no variance requested” (or, if requesting an alternate, note that a DHS variance is required per § 3102C) .
Because the CRSC does not include the numeric formulas or threshold dose limits, you must obtain those numeric values and calculation procedures from the NCRP report itself and show the calculation trace as your demonstration of compliance with § 12-31C-101 .
Related provisions
- § 3101C — Definitions used in Chapter 31C (e.g., Primary protective barrier, Secondary protective barrier, Useful beam) — useful when identifying barrier types for design.
- § 3102C — Radiation shielding barriers (requirement that all barriers meet § 12-31C-101; DHS variance authority).
- § 12-31C-101 — Reference to mandatory NCRP Reports Nos. 35, 49 and 51 (the CRSC directive to use these reports).
- Chapter 31C sections describing specific installation contexts (e.g., § 3103C on operator station shielding and § 3104C on medical therapeutic X‑ray installations) — these describe where barriers must be applied within medical spaces and should be read together with § 12-31C-101 when designing shielding.
Code references
Grounded in the retrieved California Referenced Standards Code — click a citation to read the verbatim passage:
CRSC § 1.11. High relevance — show source text
The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
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31C [DPH] RADIATION
SECTION 3101C—SCOPE
For the purpose of this chapter, the following terms shall have the meaning indicated:
PRIMARY PROTECTIVE BARRIER is a barrier to attenuate the useful beam.
SECONDARY PROTECTIVE BARRIER is a barrier to attenuate stray radiation.
STRAY RADIATION is radiation not serving any useful purpose, which includes leakage and scattered radiation.
USEFUL BEAM is the radiation which passes through the window, aperture, cone or other collimating device of the tube housing.
SECTION 3102C—RADIATION SHIELDING BARRIERS
All radiation shielding barriers in rooms and enclosures housing machines shall meet the requirements of Section 12-31C-101, Chapter 12-31C, Part 12, California Referenced Standards Code. The Department of Health Services is the only agency that may grant a variance or exception to these standards.
SECTION 3103C—MEDICAL RADIOGRAPHIC AND PHOTOFLUOROGRAPHIC INSTALLATIONS
3103C.1 Operator station. The operator’s station at the control shall be behind a protective barrier either in a separate room, in a protected booth or behind a shield which will intercept the useful beam and any radiation which has been scattered only once.
3103C.2 Patient observation and communication. Provision shall be made for the operator to observe and communicate with the patient without leaving the shielded position at the control panel. When an observation window is used, it must provide radiation atten- uation equal to that required in the surrounding barrier.
SECTION 3104C—MEDICAL THERAPEUTIC X-RAY INSTALLATIONS
3104C.1 General. All wall, floor and ceiling areas that can be struck by the useful beam, plus a border of 1 foot (305 mm), shall be provided with primary protective barriers.
3104C.2 Equipment operating above 50 kVp. Equipment operating above 50 kVp shall conform with the following: 1. The control station shielding shall either be an integral part of the building or anchored to the building. 2. The control station shall be provided with a window having radiation attenuation equal to that required by the adjacent barrier, or a mirror system, or a closed-circuit television viewing screen. The patient area must be visible to the operator with- out having to leave the protected area during exposure.
CRSC § 3103C.1 High relevance — show source text
SECTION 3103C—MEDICAL RADIOGRAPHIC AND PHOTOFLUOROGRAPHIC INSTALLATIONS
3103C.1 Operator station. The operator’s station at the control shall be behind a protective barrier either in a separate room, in a protected booth or behind a shield which will intercept the useful beam and any radiation which has been scattered only once.
3103C.2 Patient observation and communication. Provision shall be made for the operator to observe and communicate with the patient without leaving the shielded position at the control panel. When an observation window is used, it must provide radiation atten- uation equal to that required in the surrounding barrier.
SECTION 3104C—MEDICAL THERAPEUTIC X-RAY INSTALLATIONS
3104C.1 General. All wall, floor and ceiling areas that can be struck by the useful beam, plus a border of 1 foot (305 mm), shall be provided with primary protective barriers.
3104C.2 Equipment operating above 50 kVp. Equipment operating above 50 kVp shall conform with the following: 1. The control station shielding shall either be an integral part of the building or anchored to the building. 2. The control station shall be provided with a window having radiation attenuation equal to that required by the adjacent barrier, or a mirror system, or a closed-circuit television viewing screen. The patient area must be visible to the operator with- out having to leave the protected area during exposure.
3104C.3 Equipment operating above 150 kVp. Equipment operating above 150 kVp shall conform to the following: 1. The treatment room shall be provided with interlocks so that when any door of the treatment room is opened, either the machine will shut off automatically or the radiation level within the room will be reduced to an average of not more than 2 milliroentgens per hour and a maximum of 10 milliroentgens per hour at a distance of one meter in any direction from the target. After such shutoff or reduction in output, it shall be possible to restore the machine to full operation only from the control panel. 2. The control station shall be within a protective booth or in an adjacent room.
3104C.4 A minimum of one door shall be provided with an auxiliary means for being opened in case of power failure or mechanical breakdown, where large power-driven doors offer the only access to the room.
3104C.5 A flashing red warning signal light energized only when the useful beam is on shall be located adjacent to the entrance(s) to a therapy room with equipment capable of operating above 500 kVp.
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CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE
CHAPTER 31D – FOOD ESTABLISHMENTS
(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
CRSC § 1.11. High relevance — show source text
CALIFORNIA BUILDING CODE – MATRIX ADOPTION TABLE
CHAPTER 31C – RADIATION
(Matrix Adoption Tables are nonregulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
Adopting agency BSC BSC-
CGSFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC Adopting agency BSC BSC-
CGSFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6 Adopt entire chapter X Adopt entire chapter as
amended (amended
sections listed below)Adopt only those sections
that are listed belowChapter / Section The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.
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31C [DPH] RADIATION
SECTION 3101C—SCOPE
For the purpose of this chapter, the following terms shall have the meaning indicated:
PRIMARY PROTECTIVE BARRIER is a barrier to attenuate the useful beam.
SECONDARY PROTECTIVE BARRIER is a barrier to attenuate stray radiation.
STRAY RADIATION is radiation not serving any useful purpose, which includes leakage and scattered radiation.
USEFUL BEAM is the radiation which passes through the window, aperture, cone or other collimating device of the tube housing.
SECTION 3102C—RADIATION SHIELDING BARRIERS
All radiation shielding barriers in rooms and enclosures housing machines shall meet the requirements of Section 12-31C-101, Chapter 12-31C, Part 12, California Referenced Standards Code. The Department of Health Services is the only agency that may grant a variance or exception to these standards.
SECTION 3103C—MEDICAL RADIOGRAPHIC AND PHOTOFLUOROGRAPHIC INSTALLATIONS
CRSC § 31B-22 Medium relevance — show source text
3162B Anti-Entrapment Devices and Systems . . . . . . . . . . 31B-22
CHAPTER 31C RADIATION . . . . . . . . . . . . . . . . . . . . . . . . . .31C-1
3101C Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31C-3
3102C Radiation Shielding Barriers . . . . . . . . . . . . . . . . . . . . . 31C-3
3103C Medical Radiographic and Photofluorographic Installations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31C-3
3104C Medical Therapeutic X-Ray Installations. . . . . . . . . . 31C-3
CHAPTER 31D FOOD ESTABLISHMENTS. . . . . . . . . . . . . . .31D-1
3101D Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31D-3
3102D Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31D-3
3103D Buildings and Structures. . . . . . . . . . . . . . . . . . . . . . . . . 31D-3
CHAPTER 31E RESERVED. . . . . . . . . . . . . . . . . . . . . . . . . . .31E-1
CHAPTER 31F MARINE OIL TERMINALS . . . . . . . . . . . . . . .31F-1
3101F Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31F-3
3102F Audit and Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31F-6
3103F Structural Loading Criteria . . . . . . . . . . . . . . . . . . . . . 31F-19
3104F Seismic Analysis and Structural Performance. . . . 31F-34
3105F Mooring and Berthing Analysis and Design . . . . . . 31F-48
3106F Geotechnical Hazards and Foundations . . . . . . . . . 31F-55
CRSC § 31B-20 Medium relevance — show source text
3154B Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B-20
3155B Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B-20
3156B Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B-20
3157B Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B-21
3158B Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B-21
3159B Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B-21
DIVISION II – PUBLIC SWIMMING POOLS. . . . . . . . . . . . . . .31B-21
3160B Ground Fault Circuit Interrupters. . . . . . . . . . . . . . . . 31B-21
3161B Wading Pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31B-21
3162B Anti-Entrapment Devices and Systems . . . . . . . . . . 31B-22
CHAPTER 31C RADIATION . . . . . . . . . . . . . . . . . . . . . . . . . .31C-1
3101C Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31C-3
3102C Radiation Shielding Barriers . . . . . . . . . . . . . . . . . . . . . 31C-3
3103C Medical Radiographic and Photofluorographic Installations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31C-3
3104C Medical Therapeutic X-Ray Installations. . . . . . . . . . 31C-3
CHAPTER 31D FOOD ESTABLISHMENTS. . . . . . . . . . . . . . .31D-1
3101D Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31D-3
CRSC § 436.5. Medium relevance — show source text
DEPARTMENT OF HEALTH SERVICES
Authority: Sections 102, 208 and 25811.
Reference: Sections 102, 208 and 436.5.
ALL HEALING ARTS X-RAY INSTALLATIONS
Sec. 12-31C-101. All radiation shielding barriers in rooms and enclosures housing radiation machines shall comply with the mandatory standards and appendices in Report No. 35, “Dental X-RAY Protection”; Report 49, “Structural Shielding Design and Evaluation for Medical use of X-rays and Gamma Rays of Energies up to 10 MeV”; and Report No. 51, “Radiation Protection Design Guidelines for 0.1-100 MeV Particle Accelerator Facilities.” Published by the National Council on Radiation Protection and Measurements, 7910 Woodmont Avenue, Bethesda, Maryland 20814.
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12-71 AIR FILTERS
STANDARD 12-71-1
STATE FIRE MARSHAL
DESCRIPTION OF TEST APPARATUS, METHOD AND CLASSIFICATION REQUIREMENTS FOR AIR FILTERS
Sec. 12-71-100.
(a) Test apparatus.
- The test duct, made of M.S. gage galvanized sheet metal reinforced with angle irons, is 21 inches square (13 548 mm [2] ) and 13 [1] / 2 feet (4114 mm) long.
- One end of the duct is tapered to the discharge of a variable-speed blower and the other end is open to discharge. A metal filter frame is provided near the middle of the length of the duct to receive one 20 by 20 inches (508 mm by 508 mm) (nominal) filter unit. Two tightfitting doors, located to permit access to the filter frame, are each provided with a mica window to permit observation of both faces of the filter and conditions in the duct downstream from the filter.
- Two 1-inch (25 mm) pipe elbows, about 18 inches (457 mm) from the base of the test filter, form gas burner outlets adjusted to provide yellow, wavering flames. The burners consume approximately 4 cubic feet (approximately 1,000 Btu/cubic feet) of gas per minute.
- With the filter in place the air velocity is adjusted to approximately 200 linear feet per minute as measured at the discharge end of the duct by an Alnor Velometer Anemometer.
(b) Test method.
- Filters are tested clean, that is, unused. The flames are applied for 3 minutes during which time observations are made of both faces of the filter as to the downstream travel of flame or sparks and the density, duration and character of the products of combustion.
CRSC § 1224.34.2.14 Medium relevance — show source text
1224.34.2.14 Hot lab for scintigraphy (gamma camera), PET and SPECT facilities. A securable area or room shall be provided in which radiopharmaceuticals can be safely stored and doses can be calculated and prepared. 1. A single hot lab shall be permitted to serve multiple scanners and nuclear medicine modalities. 2. The hot lab shall be shielded in compliance with Section 1224.34.1.1. 3. A source storage area, a dose area and a storage area for syringe shields shall be provided.
1224.34.3 Radiotherapy service space.
1224.34.3.1 Radiation therapy space. If radiation therapy is provided, the following shall be accommodated: 1. Patient reception and waiting areas. 2. Space for medical and physics staff functions. 3. Space for equipment and supplies. 4. Housekeeping room. 5. Direct access to space provided for radiation measurement and calibration equipment, including a calibration constancy instrument and access to a secondary standard dose meter.
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INTERIOR ENVIRONMENT
5.1. A megavoltage treatment unit capable of delivering x-rays or gamma rays of effective energy 500 KeV or more and conforming to the requirements of Chapter 31C and the California Radiation Control Regulations, Califor- nia Code of Regulations, Title 17, Division 1, Chapter 5, Subchapter 4. 5.2. Access to a medium voltage or superficial treatment unit delivering 500 KeV or less, but otherwise having the same functional characteristics as the above mega-voltage units and conforming to the requirements of Chap- ter 31C and the California Radiation Control Regulations, California Code of Regulations, Title 17, Division 1, Chapter 5, Subchapter 4. 5.3. Direct access to space provided for brachytherapy equipment which shall meet the requirements of Chapter 31C and the California Radiation Control Regulations, California Code of Regulations, Title 17, Division 1, Chap- ter 5, Subchapter 4. 5.4. Shielding of the rooms shall meet the requirements of Chapter 31C and the California Radiation Control Regula- tions. California Code of Regulations, Title 17, Division 1, Chapter 5, Subchapter 4.
1224.34.3.2 Radiation protection. Cobalt, linear accelerators, hot lab and high dose rate brachytherapy rooms and simulation rooms require radiation protection. All rooms that provide radiation treatment shall be appropriately shielded. A certified physi- cist shall specify the type, location and amount of protection to be installed in accordance with final approved department layout and equipment selection. Radiation protection requirements shall be incorporated into the construction documents and comply with Chapter 31C and the requirements of California Radiation Control Regulations, California Code of Regulations, Title 17, Divi- sion 1, Chapter 5 and Subchapter 4.
1224.34.3.3 Room sizes. Rooms shall be sized as follows:
1. Cobalt rooms and linear accelerators shall be sized in accordance with equipment requirements and shall accommo- _date a gurney for litter borne patients. Layouts shall provide for preventing the escape of radioactive particles.
CRSC § 1224.34.3.2 Medium relevance — show source text
but otherwise having the_ same functional characteristics as the above mega-voltage units and conforming to the requirements of Chap- ter 31C and the California Radiation Control Regulations, California Code of Regulations, Title 17, Division 1, Chapter 5, Subchapter 4. 5.3. Direct access to space provided for brachytherapy equipment which shall meet the requirements of Chapter 31C and the California Radiation Control Regulations, California Code of Regulations, Title 17, Division 1, Chap- ter 5, Subchapter 4. 5.4. Shielding of the rooms shall meet the requirements of Chapter 31C and the California Radiation Control Regula- tions. California Code of Regulations, Title 17, Division 1, Chapter 5, Subchapter 4.
1224.34.3.2 Radiation protection. Cobalt, linear accelerators, hot lab and high dose rate brachytherapy rooms and simulation rooms require radiation protection. All rooms that provide radiation treatment shall be appropriately shielded. A certified physi- cist shall specify the type, location and amount of protection to be installed in accordance with final approved department layout and equipment selection. Radiation protection requirements shall be incorporated into the construction documents and comply with Chapter 31C and the requirements of California Radiation Control Regulations, California Code of Regulations, Title 17, Divi- sion 1, Chapter 5 and Subchapter 4.
1224.34.3.3 Room sizes. Rooms shall be sized as follows:
1. Cobalt rooms and linear accelerators shall be sized in accordance with equipment requirements and shall accommo- date a gurney for litter borne patients. Layouts shall provide for preventing the escape of radioactive particles. Openings into the room, including doors, ductwork, vents and electrical raceways and conduits, shall be baffled to prevent direct exposure to other areas of the facility. 2. Simulator, accelerator and cobalt rooms shall be sized to accommodate the equipment with patient access on a gurney, medical staff access to the equipment and patient, and service access. 3. Where a table is used, the room shall be sized to provide a minimum clearance of 4 feet (1218 mm) on three sides of the table to facilitate bed transfer and provide access to the patient. The door swing shall not encroach on the equipment space, patient circulation space or transfer space. 4. Minimum room size shall be 260 square feet (24.15 m [2] ) for the simulator room; 680 square feet (63.17 m [2] ), including the maze, for accelerator rooms; 200 square feet (18.58 m [2] ) for brachytherapy rooms; and 450 square feet (41.81 m [2] ) for cobalt rooms.
1224.34.3.4 General support area. The following areas shall be provided: 1. A gurney hold area adjacent to the treatment rooms, screened for privacy and combined with a seating area for outpatients. 2. Exam or treatment room shall be provided with a minimum of 100 square feet (9.29 m [2] ) with a minimum dimension of 8 feet (2438 mm). Each exam room shall be equipped with a handwashing station.
CRSC § 717.2.3 Medium relevance — show source text
717.2.3 Static dampers. Fire dampers and ceiling radiation dampers that are listed for use in static systems shall only be installed in heating, ventilation and air-conditioning systems that are automatically shut down in the event of a fire.
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FIRE AND SMOKE PROTECTION FEATURES
717.2.4 Mechanical, electrical and plumbing controls. Mechanical, electrical and plumbing controls shall not be installed in air duct systems.
Exception: Controls where the wiring is directly associated with the air distribution system. The wiring shall comply with the requirements of Section 601 of the California Mechanical Code and be as short as practicable.
717.2.4.1 Controls not permitted to be installed through dampers. Mechanical, electrical and plumbing controls shall not be installed through fire dampers, smoke dampers, combination fire/smoke dampers or ceiling radiation dampers unless otherwise permitted by the manufacturer and the listing.
717.3 Damper testing, ratings and actuation. Damper testing, ratings and actuation shall be in accordance with Sections 717.3.1 through 717.3.3.
717.3.1 Damper testing. Dampers shall be listed and labeled in accordance with the standards in this section.
- Fire dampers shall comply with the requirements of UL 555.
- Smoke dampers shall comply with the requirements of UL 555S.
- Combination fire/smoke dampers shall comply with the requirements of both UL 555 and UL 555S.
- Ceiling radiation dampers shall comply with the requirements of UL 555C or shall be tested as part of a fire-resistancerated floor/ceiling or roof/ceiling assembly in accordance with ASTM E119 or UL 263.
- Corridor dampers shall comply with requirements of both UL 555 and UL 555S. Corridor dampers shall demonstrate acceptable closure performance when subjected to 150 feet per minute (0.76 mps) velocity across the face of the damper during the UL 555 fire exposure test.
717.3.2 Damper rating. Damper ratings shall be in accordance with Sections 717.3.2.1 through 717.3.2.4.
717.3.2.1 Fire damper ratings. Fire dampers shall have the minimum rating specified in Table 717.3.2.1.
TABLE 717.3.2.1—FIRE DAMPER RATING Col2 TYPE OF PENETRATION MINIMUM DAMPER RATING (hours) Less than 3-hour fire-resistance-rated assemblies 1.5 3-hour or greater fire-resistance-rated assemblies 3 717.3.2.2 Smoke damper ratings. Smoke damper leakage ratings shall be Class I or II. Elevated temperature ratings shall be not less than 250°F (121°C).
717.3.2.3 Combination fire/smoke damper ratings. Combination fire/smoke dampers shall have the minimum rating specified for fire dampers in Table 717.3.2.1 and shall have the minimum rating specified for smoke dampers in Section 717.3.2.2.
CRSC § 1224.34 Medium relevance — show source text
1224.34 NUCLEAR MEDICINE.
1224.34.1 General. If nuclear medicine is provided, the following shall be provided:
1224.34.1.1 Radiation protection. A certified physicist shall specify the type, location and amount of radiation protection to be installed in accordance with final approved department layout and equipment selection. A physicist report shall also address dosing areas and circulation paths of dosed patients, including within multi-bay scanner rooms. Radiation protection require- ments shall be incorporated into the construction documents and comply with Chapter 31C and the requirements of California Radiation Control Regulations, California Code of Regulations, Title 17, Division 1, Chapter 5, and Subchapter 4.
1224.34.1.2 Nuclear medicine room. Shall be sized to accommodate the equipment and a gurney.
When provided, the following facilities shall meet the requirements below:
1224.34.1.2.1 Scintigraphy (Gamma Camera) Facilities. Shall include the following: 1. Scanner room. The scanner room shall provide a minimum clearance of 4 feet (1218 mm) at each side and the foot of the table.
2. Handwashing stations shall be provided throughout the gamma camera suite at locations of patient contact and at locations where radiopharmaceutical materials are handled, prepared or disposed of.
1224.34.1.2.2 Positron Emission Tomography (PET). Shall include the following: 1. Scanner room shall provide a minimum clearance of 4 feet (1218 mm) at each side and the foot of the table. Additional space shall be provided when PET is combined with CT and include compliance with Section 1224.18.3 and shielding requirements in Section 1224.34.1.1. 2. Cyclotron room. Where radiopharmaceuticals are prepared on-site, a cyclotron shall be provided. Cyclotron facilities shall be located in access-restricted areas. Shielding requirements for cyclotron facilities shall comply with Section 1224.34.1.1.
3. Control room. If a control room is required based on the physicist’s report, it shall be provided with a full direct view of the patient in the PET scanner. 4. Patient uptake/cool-down room. A shielded room with access to a dedicated patient toilet, to accommodate radioac- tive waste, and lavatory shall be provided. 5. Handwashing stations shall be provided throughout the PET suite at locations of patient contact and at locations where radiopharmaceutical materials are handled, prepared or disposed of. 6. Pre-procedure patient care and recovery area shall be provided to accommodate at least two stretchers. This area shall comply with Section 1224.34.2.6. 7. Imaging equipment room shall be provided in support of the equipment provided.
2025 CALIFORNIA BUILDING CODE 12-53
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INTERIOR ENVIRONMENT
8. Contaminated (hot) soiled holding shall be provided and operationally integrated to minimize incidental exposure to ionizing radiation.
CRSC § 12-16 Medium relevance — show source text
CALIFORNIA STANDARD FOR RESIDENTIAL EXCESS FLOW ACTUATED AUTOMATIC GAS SHUTOFF VALVES (SEE CCR TITLE 24, PART 5, CHAPTER 12) STANDARD 12-16-2
DIVISION OF THE STATE ARCHITECT
Authority: Sections 19200–19204, Health and Safety Code. Reference: Sections 19201.5 and 19202, Health and Safety Code.
DIVISION 1—CONSTRUCTION
SCOPE
Sec. 12-16-201. The American Society for Testing and Materials (ASTM) F2138-12(2017) Standard Specification for Excess Flow Valves for Natural Gas Service, and the American National Standards Institute (ANSI) Z21.93-2017/CSA 6.30-2017 Excess Flow Valves for Natural and LP Gas with Pressure up to 5 psig, shall be the applicable standards used by the Division of the State Architect for certification of these devices.
Sec. 12-16-201.1. Each installation of a customer-owned device that satisfies this standard shall be in accordance with the California Plumbing Code (CCR Title 24, Part 5).
2025 CALIFORNIA REFERENCED STANDARDS CODE 103
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104 2025 CALIFORNIA REFERENCED STANDARDS CODE
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12-31C RADIATION SHIELDING STANDARDS
STANDARD 12-31C-1
DEPARTMENT OF HEALTH SERVICES
Authority: Sections 102, 208 and 25811.
Reference: Sections 102, 208 and 436.5.
ALL HEALING ARTS X-RAY INSTALLATIONS
Sec. 12-31C-101. All radiation shielding barriers in rooms and enclosures housing radiation machines shall comply with the mandatory standards and appendices in Report No. 35, “Dental X-RAY Protection”; Report 49, “Structural Shielding Design and Evaluation for Medical use of X-rays and Gamma Rays of Energies up to 10 MeV”; and Report No. 51, “Radiation Protection Design Guidelines for 0.1-100 MeV Particle Accelerator Facilities.” Published by the National Council on Radiation Protection and Measurements, 7910 Woodmont Avenue, Bethesda, Maryland 20814.
2025 CALIFORNIA REFERENCED STANDARDS CODE 105
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106 2025 CALIFORNIA REFERENCED STANDARDS CODE
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12-71 AIR FILTERS
STANDARD 12-71-1
STATE FIRE MARSHAL
DESCRIPTION OF TEST APPARATUS, METHOD AND CLASSIFICATION REQUIREMENTS FOR AIR FILTERS
Sec. 12-71-100.
(a) Test apparatus.
- The test duct, made of M.S. gage galvanized sheet metal reinforced with angle irons, is 21 inches square (13 548 mm [2] ) and 13 [1] / 2 feet (4114 mm) long.
CRSC § 803.13 Medium relevance — show source text
Incidental uses 509 Interior finishes Table 803.13, 804 Live load Table 1607.1 Means of egress Aisles 1018.3
Stairway, exit access 1019 Travel distance 1006.3, 1017.2,
1006.2.1
Mixed occupancies 508.2, 508.3, 508.4 Accessory 303.1.2, 508.2 Ambulatory care facilities 422 Assembly 303.1.2
Assembly spaces 1030 Exit signs 1013.1 Guards 1015.2, 1030.17 Main exit 1030.3
Open air 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Panic hardware 1010.2.8, 1010.4.1 Smoke-protected 1005.3.1, 1005.3.2, 1006.3, 1009.6.4, 1019.3, 1027, 1030.6.2 Travel distance 1006.2.1, 1006.3, 1017.2, 1030.7 Mixed occupancies 508.3, 508.4 Accessory 508.2 Education 303.1.3
Live/work units 508.5 Mall buildings 402 Other occupancies 303.1.1, 303.1.2, 303.1.3 Parking below/above 510.7, 510.9 Religious facilities 303.1.4 Special mixed 510.2 Motion picture theaters 409, 507.12 Occupancy exceptions 303.1.1, 303.1.2, 303.1.3, 303.1.4, 305.1.1, 305.2.1 Plumbing fixtures Chapter 29 Risk category Table 1604.5 Seating, fixed (see Seating, Fixed) Seating, open-air assembly seating 1030.6.3 Seating, smoke-protected 1030.6.2 Sprinkler protection 410, 504.3, 506.2, 507.12, 507.4, 507.6, 507.7, 903.2.1 Stages and platforms 410 Standpipes 905.3.2, 905.5.1 Unlimited area 507.12, 507.4, 507.4.1, 507.6, 507.7 Assisted Living (see Group I-1 and Group R-4) 308.2, 310.5, 420 Atmospheric Ice Loads 1614 Atrium 404
Alarms and detection 404.4, 907.2.15 Enclosure 404.6, 707.3.6 Interior finish 404.8 Means of egress 404.9, 404.10, 404.11, 1006.3.2, 1017.3, 1019.3, 1023.2,
1028.2
Smoke control 404.5, 909 Sprinkler protection 404.3 Standby power 404.7 Travel distance 404.9, 1006.2.1, 1006.3, 1017.2
Use 404.2
Attic 202
Frequently asked questions
Who exactly decides if an alternate shielding method is acceptable?
Only the Department of Health Services may grant a variance or exception to the referenced NCRP standards; local code officials cannot override § 12-31C-101 without that variance authority under § 3102C.
Where do I find the numeric formulas and attenuation tables I need?
Numeric methods, attenuation coefficients, allowable dose limits, and example calculations are inside the NCRP reports cited by § 12-31C-101 — those reports (Nos. 35, 49, 51) must be consulted directly; the CRSC text itself directs you to use them but does not reproduce their technical content.
Is a physicist report required by the CRSC?
The CRSC sections § 3102C and § 12-31C-101 require use of the NCRP standards but do not themselves mandate that a certified physicist produce a report. (Other parts of the California Building Code and agency rules commonly require a certified physicist; check project‑specific CBC sections and the enforcing authority for that submittal requirement.)
If my project mixes dental and accelerator equipment, which standard applies?
Apply the specific NCRP report appropriate to each machine/space: dental spaces -> NCRP Report No. 35; particle accelerators -> NCRP Report No. 51; medical X‑ray/gamma up to 10 MeV -> NCRP Report No. 49, as required by § 12-31C-101.
What should I include in the construction documents to demonstrate compliance?
At minimum: the shielding calculations using the applicable NCRP report (showing assumptions and results), drawings that identify barriers and materials, and a clear statement that the design follows the relevant NCRP report per § 12-31C-101. The CRSC requires use of the reports but does not prescribe the exact submittal checklist — check the enforcing authority for their plan-check requirements.
More in California Referenced Standards Code
- Administration and scope — CRSC Chapter 12 overview
- Air filter standards (Chapter 12‑71)
- Building and facility access / accessibility standards (Chapters 12‑11A, 12‑11B)
- Engineering regulations — quality and design of construction materials (12‑16 series)
- Exits and means of egress (Chapters 12‑10 series)
- Protective signaling systems and detectors (Chapters 12‑72‑1, ‑2, ‑3)
- Radiation shielding standards (Chapter 12‑31C)
- Referenced standards index / cross‑reference table (Part 12 listing of referenced standards)
- Releasing systems for security bars (egress-release standards)
- Standards for insulating materials (Chapter 12‑13)
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