Regulatory Guide 5.27: Difference between revisions

From kanterella
Jump to navigation Jump to search
(Created page by program invented by StriderTol)
(Created page by program invented by StriderTol)
Line 1: Line 1:
{{Adams
{{Adams
| number = ML003740050
| number = ML14290A268
| issue date = 06/30/1974
| issue date = 07/23/2015
| title = Special Nuclear Material Doorway Monitors
| title = Rev. 1, Special Nuclear Material Doorway Monitors
| author name =  
| author name = Tardiff A
| author affiliation = NRC/RES
| author affiliation = NRC/NSIR
| addressee name =  
| addressee name =  
| addressee affiliation =  
| addressee affiliation =  
| docket =  
| docket =  
| license number =  
| license number =  
| contact person =  
| contact person = Jervey R
| document report number = RG-5.27
| case reference number = DG-5038
| document report number = RG-5.027 Rev 1
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 12
| page count = 14
}}
}}
{{#Wiki_filter:June 1974 U.S. ATOMIC ENERGY COMMISSION  
{{#Wiki_filter:U.S. NUCLEAR REGULATORY COMMISSION
REGULATORY  
July 2015 OFFICE OF NUCLEAR REGULATORY RESEARCH
GUIDE DIRECTORATE
Revision 1 REGULATORY GUIDE
OF REGULATORY
  Technical Lead A. Tardiff  Written suggestions regarding this guide or development of new guides may be submitted through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading
STANDARDS
-rm/doc-collections/reg
REGULATORY  
-guides/contactus.html
GUIDE 5.27 SPECIAL NUCLEAR MATERIAL DOORWAY MONITORS  
.    Electronic copies of this regulatory guide, previous versions of this guide, and other recently issued guides are available through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading
-rm/doc-collections/.  The regulatory guide is also available through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading
-rm/adams.html, under ADAMS Accession No.
 
ML14290A268. The regulatory analysis may be found in ADAMS under Accession No. ML12237A124 and the staff responses to the public comments on DG
-5038 may be found under ADAMS Accession No. ML14288A653.  REGULATORY GUIDE 5.27 (Draft was issued as DG
-5038, dated March 2014)
  SPECIAL NUCLEAR MATERIAL DOORWAY MONITORS


==A. INTRODUCTION==
==A. INTRODUCTION==
Paragraph (b), "Exit Requirement," of § 73.60, "Ad ditional Requirements for the Physical Protection of Special Nuclear Material at Fixed Sites," of 10 CFR Part 73, "Physical Protection of Plants and Materials," requires that individuals exiting from material access areas be searched for concealed special nuclear material (SNM). This guide describes means acceptable to the Regulatory staff for employing SNM doorway monitors to comply with that requirement.
Purpose  The U.S. Nuclear Regulatory Commission (NRC) developed this regulatory guide (RG) to describe a method that the NRC staff considers acceptable to implement the search requirement for concealed special nuclear material (SNM) applied to personnel, vehicles, packages and all other materials exiting a material access area (MAA). 
 
For holders of a reactor license under Title 10 of the Code of Federal Regulations (10 CFR)
Part 50, "Domestic Licensing of Production and Utilization Facilities" (Ref. 1), a combined license under
10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants" (Ref. 2), or a fuel cycle facility license under
10 CFR Part 76, "Certification of Gaseous Diffusion Plants" (Ref. 3), having the need to possess or use SNM within their facility, the NRC typically has included in their license a condition granting a general license to use SNM under
10 CFR Part 70, "Domestic Licensing of Special Nuclear Material."
  Applicable Rules and Regulations The requirements for physical protection found within
10 CFR Parts 50, 52, 70, and 76 refer to the physical protection requirements of  
10 CFR Part 73, "Physical Protection of Plants and Materials." Part 73 (Ref. 4) requires, in part, in
10 CFR 73.46(d)(9) and
10 CFR 73.60(b), that each individual , package, materials and vehicle exiting an MAA is searched for concealed SNM. Specific testing and maintenance requirements, as stated in
10 CFR 73.20(b)(4), 10 CFR 73.46(g), and
10 CFR 73.60(d)(1) also apply.
 
Related Guidance Regulatory Guide 5.7, "Entry/Exit Control of Personnel Access to Protected Areas, Vital Areas, and Material Access Areas"
(Ref. 5)  NUREG 1964, "Access Control Systems: Technical Information for NRC Licensees" (Ref. 6)
 
RG 5.27, Rev. 1, Page 2  Purpose of Regulatory Guides The NRC issues RGs to describe to the public methods that the staff considers acceptable for use in implementing specific parts of the agency
's regulations, to explain techniques that the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to applicants.  Regulatory guides are not substitutes for regulations and compliance with them is not required.
 
Methods and solutions that differ from those set forth in RGs will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a permit or license by the Commission.
 
Information Collection Requirements This RG contains information collection requirements covered by
10 CFR Part 73 , "Physical Protection of Plants and Materials,"
that the Office of Management and Budget (OMB) approved under OMB control number 3150
-0002.  The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control number.


==B. DISCUSSION==
==B. DISCUSSION==
Special nuclear material doorway monitors provide an efficient, sensitive, and reasonably unobtrusive means of searching individuals exiting from a material access area for concealed SNM. With proper installation and opera tion, gram quantities or less of SNM can be detected with a high level of reliability while maintaining a low false alarm rate. I. Theory of Operation The doorway monitor is composed of a detector unit(s), associated electronics, and alarm logic. The detector unit(s) is sensitive to the radiations which emanate from the SNM and responds to these radiations (usually gamma rays) by generating current pulses. These pulses are amplified, filtered, and fed to alarm logic v'hich interprets the number (or rate) of pulses in some period of time, for example, one second. The alarm logic may be either a digital or analog system; in either case, if the number (or rate) of pulses exceeds a set level, an alarm condition ensues.2. General Characteristics Typically, the detectors of a doorway monitor are NaI(Tl) scintillators or solid or liquid organic scintilla tors. Geiger-Mueller detectors have also been used in this application, although the lower intrinsic efficiency of these detectors renders them less suitable than scintilla tion detectors.
Reason for Revision This RG is being revised because it was out
-of-date with current related guidance and references in the CFR.  Related specifications and standards for SNM monitors and metal detectors have been updated or developed since the previous revision was issued in 1974.
 
This revision has been developed to provide detection practices and criteria that licensees may use to demonstrate compliance with NRC regulations in
10 CFR Part 73 and to augment programmatic information within the general reference, NUREG-1964, "Access Control Systems: Technical Information for NRC Licensees," (Ref. 6) issued in April of 2011
.  Background
 
Special nuclear material doorway monitors provide an efficient, sensitive, and reasonably unobtrusive way of searching individuals for concealed SNM
upon exit from an MAA. With proper installation and operation, gram quantities or less of SNM can be detected with a high level of reliability while maintaining a low false alarm rat
 
====e. Portal type walk====
-through metal detectors are often used in conjunction with radiation detection to assure that personnel entering or leaving MAAs are screened for metallic nuclear shielding materials.
 
Theory of Operation The doorway monitor comprises one or more detector unit(s), associated electronics, and alarm logic. The detector units are sensitive to the SNM radiation and responds to the emitted radiation (gamma rays and neutrons) by generating electronic current pulses. These pulses are amplified, filtered, and fed to alarm logic circuits that interpret the number (or rate) of pulses during a sampling. The alarm logic may be either a digital or analog system.  In either case, if the rate of pulses exceed a set level, the alarm is triggered.  Additional information pertaining to detector theory can be found in Knoll's, "Radiation Detection and Measurement." (Ref.7)   
RG 5.27, Rev. 1, Page 3  General Characteristics Doorway Monitors Doorway monitors detect gamma
-ray radiation using scintillation or semiconductor detectors.  To detect neutrons, plastic scintillators or gas
-filled proportional counters are use
 
====d. Geiger====
-Mueller counters have been used in this application; however, their lower intrinsic efficiency renders them less suitable than scintillation detectors.  Scintillation detectors are often used for discriminating pulses based o n imparted energy.  Plastic scintillation detectors have the advantage of responding well to gamma
-ray and energetic neutrons whereas the sodium iodide thallium
-activated NaI(Tl) scintillation detectors have good gamma-ray sensitivity but poor neutron respons
 
====e. Helium====
-3 (He-3) gas is used in tubes as a proportional counter for neutron detection.  The trend in industry is to use both scintillation detectors and He-3 detectors for doorway monitor systems.
 
Detectors are arranged so that a detection area is defined by a plane perpendicular to the line of passage of individuals through the doorway monitor.  Various arrangements of the detectors are possible.
 
However, specific placement of detectors should be based on the need to eliminate areas of no detection
.  Commercially available doorway monitors are equipped with an automatic radiation background updating system that periodically monitors and averages the background count rate.  A doorway monitor equipped with an automatic radiation background updating system is also provided with a treadle pad or beam break system to indicate that the zone of detection is occupied.  When the zone of detection is occupied, the radiation level detected by the doorway monitor is compared to the mean background.  If the level is greater than the mean background by a predetermined trigger level, an alarm is actuated.  Alarm actuation point is usually determined by comparing the radiation levels within the zone of detection while occupied to the sum of the mean background while unoccupied and a factor to account for predetermined statistical accuracy
.1 Thus, the condition for an alarm can be written as
:      G>B+n(B) 1/2  Where B is the mean background, G is the radiation level within the zone of detection while occupied and n is a multiplier, usually between 4 and 10.
 
2 Although the automatic background updating system allows unattended use of the doorway monitor, for technical reasons, the system may be less effective in certain situations.  Techniques to prevent this are provided in the regulatory position.
 
Whether or not a doorway monitor is equipped with an automatic background updating system, high background activity will decrease sensitivity.  Measuring activity in the zone of detection for longer
 
1  The square root of the mean of a Poisson
-distributed quantity is the unbiased estimate of the standard deviation of that quantity. 2  Note that, in general, for a count rate system, the condition for alarm should be modified to account for the response time of the instrument as follows:
    G>B+n(B)1/2 (1-e-t/r)  Where t is the counting time and r is the time constant of the instrument. If, as should be the case, t/r>5, the added factor is essentially unity.
 
RG 5.27, Rev. 1, Page 4  periods of time will compensate somewhat for a high radiation background.  However, longer measurement periods can make the use of the doorway monitor less convenient.  Because of the adequate radiation detection sensitivity and high
-throughput capability associated with processing many personnel through the detection system on a daily basis, walk
-through pedestrian monitors are the primary SNM detection system used in personnel portals at MAAs.
 
Hand-Held Monitors Hand-held monitors can use detectors made of NaI(Tl), plastic scintillators, semiconductors, or He-3 gas-filled tubes.  Commercially available systems have rechargeable batteries that assist in ensuring continuous availability.  Training the operator of a hand
-held monitor is essential. The operator must scan an individual in the correct way for a hand
-held monitor to be fully effective.  In addition, the operator must understand the capabilities of the equipment, when the equipment is working within acceptable parameters and when it is not.
 
Radioisotope identification systems that detect radiation with high purity germanium (HPGe) detectors can be hand
-held.  These monitors are commercially available and may have a special cooling device, instead of a cryogenic bath, to cool the semiconductor HPGe crystal.  Special cooling devices (e.g., Stirling cooler) allow a light
-weight design useful as a hand held detection system.
 
Hand-held monitors complement SNM search operations by enabling a more thorough search of an individual to locate the radiation source after a doorway monitor has alarmed, enabling pedestrian searches to continue when a doorway monitor is inoperative and, if technically outfitted to do so, identify specific radionuclide(s) causing a doorway alarm.
 
Because of the time required to scan an individual with a hand-held monitor, it is used as a secondary SNM detection system at an MAA personnel portal.
 
Vehicle Monitors
 
Two types of automatic vehicle monitors presently in use are the vehicle monitoring station and the drive-through vehicle monitor. Commercially available vehicle drive
-through SNM portals generally consist of two vertical cabinets containing both large plastic scintillators and decision
-making electronics.  These scintillators continuously measure the gamma ray background intensity and adjust the alarm threshold to maintain a constant nuisance alarm rate.  The sensitivity of SNM vehicle monitors var y for different types of vehicles and depends on the size, spacing, and number of detectors.  For an individual detector configuration and vehicle, two of the dominate sensitivity factors are the occupancy background suppression and shielding provided by the components of the vehicle.
 
3    Standards Associated with Monitoring
 
Selection of equipment, setup, operation calibration, testing and performance evaluation of portal monitoring systems should be performed using procedures designed for the specific facility and configuration.  Guidance that pertains to the use of radiation detection and metal detection instrumentation is available from several standards organizations.  The NRC staff finds that the following guidance , which has been successfully used by SNM licensees and is available from the American Society for Testing and Materials (ASTM), Conshohocken, Pennsylvania, acceptable for use:                                           
    3  LA-UR-96-4505: "An Optimized International Vehicle Monitor," (Ref. 8)
 
RG 5.27, Rev. 1, Page 5  ASTM C1189
-11, "Standard Guide to Procedures for Calibrating Automatic Pedestrian SNM Monitors." (Ref.
 
9)    ASTM C1112
-99 (2005), "Standard Guide for Application of Radiation Monitors to the Control and Physical Security of Special Nuclear Material." (Ref.
 
10)    ASTM C1237
-99 (2005), "Standard Guide to In
-Plant Performance Evaluation of Hand
-Held SNM Monitors." (Ref.
 
11)    ASTM C993-97 (2012), "Standard Guide for In
-Plant Performance Evaluation of Automatic Pedestrian SNM Monitors." (Ref. 1
2)    ASTM C1270
-97 (2012), "Standard Practice for Detection Sensitivity Mapping of In
-Plant Walk Through Metal Detectors." (Ref. 1
3)    ASTM C1269
-97 (2012), "Standard Practice for Adjusting the Operational Sensitivity Setting of In
-Plant Walk
-Through Metal Detectors." (Ref. 1
4)    ASTM C1309
-97 (2012), "Standard Practice for Performance Evaluation of In
-Plant Walk-Through Metal Detectors." (Ref. 1
5)    In addition, ASTM C1236
-99 (2005), Standard Guide for In
-Plant Performance Evaluation of Automatic Vehicle SNM Monitors (Ref. 16) was withdrawn in 2014, but can be used by licensees as a development tool.
 
Harmonization with International Standards The International Atomic Energy Agency (IAEA) has established a series of safety guides and standards constituting a high level of safety for protecting people and the environment.  IAEA safety guides present international good practices and increasingly reflects best practices to help users striving to achieve high levels of safety.  Pertinent to this RG, "IAEA Nuclear Security Series No. 13, Nuclear Security Recommendations on Physical Protection of Nuclear Material and Nuclear Facilities," issued January 2011, (Ref. 17) et. al., addresses considerations necessary for a nuclear material security program.  While the NRC has an interest in facilitating the harmonization of standards used domestically and internationally, the NRC does not specifically endorse the IAEA document, and is only acknowledging that it may be useful as a reference for general information.
 
RG 5.27, Rev. 1, Page 6  Documents Discussed in Staff Regulatory Guidance This RG endorses the use of one or more codes or standards developed by external organizations, and other third party guidance documents.
 
These codes, standards and third party guidance documents may contain references to other codes, standards or third party guidance documents ("secondary references").
  If a secondary reference has itself been incorporated by reference into NRC regulations as a requirement, then licensees and applicants must comply with that standard as set forth in the regulation.
 
If the secondary reference has been endorsed in a RG as an acceptable approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC staff for meeting that regulatory requirement as described in the specific RG.  If the secondary reference has neither been incorporated by reference into NRC regulations nor endorsed in a RG, then the secondary reference is neither a legally
-binding requirement nor a "generic" NRC approval as an acceptable approach for meeting an NRC requirement.
 
However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified and consistent with current regulatory practice, consistent with applicable NRC requirements such as
10 CFR 50.59.  C.  STAFF REGULATORY GUIDANCE
  1. Considerations for SNM Doorway Monitors a. General  (1) Metal detectors should be used in conjunction with an SNM doorway monitor as an SNM detection system and can be one of the two required separate searches for concealed SNM (10 CFR 73.46(d)(9)).  The metal detector unit should be installed in the pedestrian passageway as described in RG 5.7, "Entry/Exit Control of Personnel Access to Protected Areas, Vital Areas, and Material Access Areas" with the SNM monitor in such a way that objects cannot be passed over, around, or under the detection area without being appropriately searched. The entire process begins when the individual, package, or other item approaches the monitoring area and ends when the individual, package or other item is exiting the monitoring area after the completion of a monitoring event.
 
(2) Alarm actuation for detectable metal mass should be the amount necessary to shield SNM that would allow a protracted theft of a formula quantity of strategic SNM to occur before the inventory process identifies it as missing
. (3) The detector elements should be designed and positioned so that detection sensitivity is as uniform as possible over the zone of detection; in no case should any area within the zone of detection not be able to detect SNM.
 
(4) Power, sensitivity, and other controls of the doorway monitor and metal detector should be tamper-safe when unattended.
 
Doorway monitors and metal detectors that are secured behind locked and alarmed doors when unattended is an acceptable alternative measure to implementing tamper
- safe devices on the SNM monitoring system.  (5) Metal and SNM detection equipment should be provided with uninterruptible power sources and/or emergency generator power.
 
(6) Signal lines connecting alarm relays to the alarm monitors for both metal and SNM
detectors should be supervised electronically or by direct surveillance to detect tampering.
 
RG 5.27, Rev. 1, Page 7  (7) Some doorway monitors may require an individual to occupy the detection area for a specified time (e.g., longer than what a normal walking pace would provide).  In this case, the doorway monitor should be provided with a treadle pad and a timer to ensure that the zone of detection is occupied for the requisite time.  Audible and visual alarms should actuate if the individual being searched does not occupy the detection area for the entire count period. (8) The doorway monitor should be equipped with a high
-background radiation alarm, which will announce if the measurement of the radiation background exceeds the appropriate maximum permissible background.  The doorway monitor should not be used during periods of high background radiation.  Calibration and determination of allowable background thresholds should be done in accordance with ASTM C1189-11, (Ref. 9)    (9) System specifications guidance for specific radioisotopes are identified below. See ASTM C1112
-99(2005), (Ref. 10) for supporting information.


Detectors are arranged such that a detection area is defined by a plane perpendicular to the line of passage of individuals through the doorway monitor. Various arrangements of the detectors are possible;
(a) Plutonium-239.  A doorway monitor used to detect plutonium (Pu) should be capable of detecting 0.5grams of plutonium with an isotopic content of at least
however, specific placement of detectors is usually dictated by the need to eliminate dead spots.  Some commercially available doorway monitors are equipped with an automatic background updating system. The automatic background updating system periodically monitors and averages the background.
93 percent Pu
-239 and less than 6.5 percent Pu
-240.  The Pu should contain less than 0.5 percent impurities. The form of the material should be a metallic sphere or cub


A doorway monitor equipped with an automatic back ground updating system is also provided with a treadle pad or beam-break system to indicate that the sensitive area is occupied.
====e. The impact of Am====
-241, a Pu decay product that will build up over time and emit increasing amounts of 60
-keV gamma radiation, must be minimized by including a cadmium filter 0.04 cm to 0.08 cm thick as part of the source encapsulation.  Protective encapsulation should be in as many layers as local rulecm thickness) stainless steel or nickel that minimize unnecessary radiation absorption.  The source should be encased in a minimum of 3 mm brass and detected at a 50
percent probability of detection with a 95 percent confidence limit.  The false alarm rate should be less than 0.1 percent. (b) Uranium-235.  A doorway monitor used to detect uranium
-235 (U-235) should be capable of detecting highly enriched (i.e., 20
percent or more) uranium containing at least 93 percent U-235 and less than 0.25 percent impurities.  The form of the material should be a metallic sphere or cube
. Encapsulation should  be applied in such manner that it minimizes unnecessary radiation absorption in the encapsulation.  The source should be encased in a minimum of 3 mm brass and detected at a 50
percent probability of detection with a 95 percent confidence limit.  The false alarm rate should be less than 0.1 percent. (c) Uranium-233.  Adequate sensitivity for uranium-233 (U-233) may be demonstrated by meeting the detection requirements for U
-235.


When the sensitive area is occupied, the radiation level detected by the doorway monitor is compared with the mean background.
RG 5.27, Rev. 1, Page 8  2. Operations with Doorway and Hand
-Held Monitors In general, doorway monitors are the primary method used to search for concealed SNM, hand-held monitors are secondary, and a physical search is tertiary.  Doorway monitors should be used in locations with minimum background radiation and minimum background radiation fluctuation.  If circumstances dictate the use of a doorway monitor in an area of high background radiation, sufficient shielding should be provided to maintain necessary sensitivity.


If the level is "significantly" greater than the mean background, an alarm condition ensues. Significance is usually deter mined by comparing the radiation level when the sensitive area is occupied with the mean background plus some multiple of the square root of the mean back ground* *The square root of the mean of a Poisson-distributed quantity is the unbiased estimate of the standard deviation of that quantit
a. The procedures, or changes to procedures developed to implement requirements of  
10 CFR 73.46 should be prepared sufficiently in advance of intended implementation to provide verification of satisfactory performance.


====y. USAEC REGULATORY ====
b. The plan for metal detection equipment functionality and performance testing periodicity, procedures, and test sources should be submitted to the NRC for approval within
GUIDES Copies of published guides may be obtained by request indicating the divisions desired to the US. Atomic Energy Commission, Washington, D.C. 20545, Regulatory Guides are issued to describe and make available to the public Attention:
360 days for licensed operating facilities, 180
Director of Regulatory Standards.
days before revising existing licensee SNM search programs, and 180 days before initial start of operations for newly licensed facilities.


Comments and suggestions for methods acceptable to the AEC Regulatory staff of implementing sPecific parts of improvements in these guides ae encouraged and should be sent to the Secretary the Commission's regulations, to delineate techniques .ned by the staff in of the Commission, US. Atomic Energy Commission, Washington, D.C. 20545, evaluating specific problems or postulated accidents, or to provide guidance to Attention:
c. During use, the doorway monitor system should check the radiation background and adjust the measurement offset at least every 15 minutes.
Chief, Public Proceedings Staff.  applicants.


Regulatory Guides are not substitutes for regulations and compliance with them is not required.
d. Doorway monitors shall be attended by two armed guards at an MAA (10 CFR 73.46 (d)(9)) within a facility containing a formula quantity of strategic SNM.  The two armed guards may consist of a guard manning the SNM monitoring system and the other providing oversight of the SNM monitoring system activities by residing in an adjacent protective enclosure.


Methods and solutions different from those set out in The guides ae issued in the following ten broad divisions:
Doorway monitors should be attended at non
the guides will be acceptable if they provide a basis for the findings requisite to the imuance or ontinuance of a permit or license by the Commission.
-power reactors.


1. Power Reactors 6. Products 2. Reaseerd enid Test Reactors
e. Each individual to be checked should, in turn, enter the doorway monitor detection area and be required to remain still long enough for the device to operate properly.


===7. Transportation ===
f. With the individual in the doorway monitor detection area, an alarm should audibly and visually announce in the vicinity of the monitor if the activity in the detection area exceeds the set alarm threshold for radiation, possibly indicating the presence of SNM.
3. Fuels and Materials Facilities
8. Occupational Health Published guidas will be revised periodically, as appropriate, to accommodate
4. Environmental and Siting 9. Antitrust Review comments amd to refloct new informeaion or experience.


5. Materials and Plant Protection
g. When a doorway monitor signals an alarm, the individual generating the alarm should pass through the monitor a second time to confirm the signal.  If the second pass through the SNM monitor does not result in a detection, then a third pass through the monitor should be conducted to verify no detection.  If the second pass through the monitor also generates an alarm, the individual should be retained and subjected to a body search, typically with a hand
10. General Thus the condition for an alarm can be written as G > B + n, where B is the mean background, G is the radiation level with the sensitive area occupied, and n is a multiplier, usually an integer between 4 and 10.* The value of n directly affects the false alarm rate, and the combination of B and n affect the sensitivity.
-held monitor, as described in ASTM C1237
-99 (2005), (Ref. 11) to locate and identify the source of the signa


Although the automatic background updating system allows unattended use of the doorway monitor, for technical reasons, the system may be less effective in certain situations.
====l. If the hand====
-held monitor does not confirm the alarm signals generated by the doorway monitor, the hand-held monitor should be tested against a known source to confirm it is working properly.  If it responds to the source in the anticipated manner, it should be concluded that the doorway monitor should be tested, repaired if necessary, and retested before returning to service. The individual generating the alarm should be released after confirmation that no SNM was detected.


Techniques to prevent this are des cribed in the Regulatory Position.
If detection is suspected to be from SNM contamination, health physics personnel should verify this finding.  A monitoring flow diagram is provided in Figure 1.


Doorway monitors not equipped with an automatic background updating system either must rely on the inherent sensitivity of the instrument and low back ground variation to ensure that concealed SNM will be detected or must be attended so that a measurement of background can be taken immediately prior to use and the alarm level set to maintain the desired sensitivity to concealed SNM. As with the doorway monitor equipped with an automatic background updating system, a doorway monitor not so equipped compares the activity with the detection area occupied with some set value, usually the measurement of background taken just prior to use. In any case, the expression above can be used as a condition of alarm by replacing B + nr'Wwith the set level.  Whether or not a doorway monitor is equipped with an automatic background updating system, high back ground activity will decrease sensitivity.
h. A hand-held SNM monitor should be used when the doorway monitor is not functioning as intended.  Search personnel should be trained on the correct use of the hand-held monitoring.  A hand-held monitor should have the capability to identify specific radioisotopes.


Measuring activ ity for longer periods will somewhat compensate for high background;
RG 5.27, Rev. 1, Page 9  3.  Physical Searches and Training a. A physical search for concealed SNM should be conducted as necessary.
however, longer measurement periods will make use of the doorway monitor less convenient.


C. REGULATORY
b. To enhance the probability of detection, random search es for concealed SNM at the protected area boundary may be conducted, including search es of hand-carried items.
POSITION 1. Minimum Qualifications for SNM Doorway Monitors a. General (1) SNM Doorway monitors should be used in conjunction with a metal detector and should be installed in a passageway (see Regulatory Guide 5.7, "Control of Personnel Access to Protected Areas, Vital *Note that, in general, for a count rate system, the condition for afarm should be modified to account for the response time of the instrument as follows: G > B + n1]0l -e-t/7) where t is the counting time and r is the time constant of the instrument.


If, as should be the case, t/,r > 5 the added factor is essentially unity.Areas, and Material Access Areas,") in such a manner that objects cannot be passed over, around, or under the detection area. .(2) The detector elements should be designed and positioned so that detection sensitivity is as uniform as possible over the detection area; in no case should any areas where SNM is not detectible be permitted.
c. At facilities with formula quantities of strategic SNM, personnel having search duties and responsibilities must be trained and qualified
.(10 C FR 73.45(g)(1)(i)).
    Pedestrian in Monitoring Zone Sets Off Alarm at First and Second Pass Hand-Held Detector Search for Source Nuclide?SNM?Tactical Response by Security Release Pedestrian Release Pedestrian Document False Alarm for Later Investigation Yes No Yes No Document Type of Nuclide Detected Figure 1  Flow diagram for SNM searches


(3) Power, sensitivity, and other controls of the doorway monitor should be tamper-safed when unat tended.  (4) Signal lines connecting alarm relays to the alarm monitor should be supervised.
RG 5.27, Rev. 1, Page 10  4. Calibration, Testing, Maintenance, and Operating Instructions a. Calibration Doorway and hand
-held monitors should be calibrated with a source of the amount, configuration, and variety of SNM to be detecte


(5) Some doorway monitors may require an indi vidual to occupy the detection area for a specified time, longer than a normal walking pace would provide. If this is the case, the doorway monitor should be provided with a treadle pad and a "clock" device to assure that the detection area is occupied for the requisite time. An aural and visual indication should be given if an individual being searched does not occupy the area sufficiently long.  b. System Specification
====d. Doorway and hand====
(1) Plutonium-239.
-held monitor calibration should be conducted in accordance with Reference
7 or as recommended by the manufacturer. Calibration should be conducted before initial use and after monitor repair or maintenance.  Calibration should be conducted at least every three months.


A doorway monitor used to detect plutonium should be capable of detecting a minimum of 0.5 gram of plutonium-239 encased in a minimum of 3 mm of brass at a 90% confidence limit.  The false alarm rate should be less than 0.1% (Appendix C). (2) Uranium-233.
As a quality assurance measure, consideration should be given to having SNM calibration standards traceable to certified reference standards or materials. b. Testing (1) Doorway , Hand-Held and Vehicle SNM Monitors Methods of performance testing doorway and hand
-held monitors are found within ASTM C993-97(2012), (Ref. 12) and Reference 9 (as well as reference
1 3).  The se references may be used to develop instructions for testing SNM monitors to assure system specifications are met.  Daily testing should be a simple functional test (i.e. operational test) to assure the detector is working.


A doorway monitor used to detect uranium-233 should be capable of detecting within 4 hours of purification*
Daily testing should be performe d during each shift, or once per day if there is only one shift. Reference 9 describes an acceptable approach for daily testing.
a minimum of 1 gram of uranium-233 containing between 7 and 10 ppm of uranium-232 encased in a minimum of 3 mm of brass at a 90% confidence limit. The false alarm rate should be less than 0.1% (Appendix C).  (3) Uranium-235.


A doorway monitor used to detect uranium-235 should be capable of detecting a minimum of 3 grams of uranium-235 contained in uranium enriched to 20% or more in the uranium-235 isotope encased in a minimum of 3 mm of brass at a 50% confidence limit. The false alarm rate should be less than 0.1% (Appendix C).  2. Use of Doorway Monitors In general, doorway monitors should be used in locations of minimum background and minimum back ground fluctation.
As described in reference
9 and reference 1
1 , testing sources may be different than those used during calibration.


If circumstances dictate use of a doorway monitor in an area of high background, sufficient shielding should be provided to maintain necessary sensitivity.
(2) Metal Detectors Sensitivity mapping and operational sensitivity testing methods are described within ASTM C1270
-97 (2012), (Ref. 13), ASTM C1269-97 (2012), (Ref 14) and ASTM C1309-97 (2012), (Ref 15).  The references may be used to develop instructions for performance testing the metal detection system used to search for concealed, shielded strategic SNM.  The metal detection system should be capable of detecting the minimum metal shielding concealed anywhere on an individual three times out of three trials.  Performance testing should be conducted at least once every three months. The performance testing should include passing the minimum metal test source through a honeycomb configuration test apparatus that covers the entire detection area as described


a. Attended Doorway Monitor (1) If the doorway monitor is attended during use, it need not be equipped with an automatic
in references 1 3 , 1 4 and 1 5.  The honeycomb channels should be a maximum of 6 inches by 6 inches in dimension. The test source should be passed through the detection area as close as possible to the same rate (speed) as a pedestrian walking through the metal detector unit.  Attaching the metal test source to a wooden dowel rod to conduct this test can facilitate the effective rate of passage of the metal source through the honeycomb test apparatus. A detection of the metal test source in each of the honeycomb test channels constitutes an acceptable performance test.
*Purification means removal of all decay products.5.27-2 background updating system, although such capability is preferred.


(2) Prior to each use* of a doorway monitor not equipped with an automatic background updating system, a measurement of background should be taken, and the alarm threshold should be set to the proper value listed in Table I for the measured background and the proper n value as determined in Appendix B. Each individual to be checked should, in turn, enter the detection area and be required to remain sufficiently long for the device to operate properly.
Daily operability testing should be conducted once per shift, or at least daily.


During use, the background should be checked and the alarm threshold reset at least each 15 minutes.
c. Maintenance Metal detection and SNM monitoring equipment shall be maintained to be operable and effectiv e as intended (10 CFR 73.20(4), 10 CFR 73.46(g), and
10 CFR 73.60(d)(1)). 
RG 5.27, Rev. 1, Page 11  d. Operating Instructions Operating instructions should be available near the search activity.  The procedural elements listed below should be included in the procedures for the search activity.  A management system shall provide for the development, revision, implementation, and enforcement of security procedures (10 CFR 73.46 (b)(3)).  Written procedures detailing the duties of search personnel for operation of SNM monitors and metal detection equipment shall be developed (10 CFR 73.46 (b)(3)(i)).
Procedures should address the following:
  metal detection threshold criteria,  test sources and their use,  monitor background reduction and sensitivity,  searching pedestrians with doorway and hand
-held monitors,  recording, retention, and analysis of monitor performance data,  recording and resolution of alarm events,  quarterly performance testing,  daily operational testing,  environmental operating constraints (e.g., temperature and humidity),  search operations during an emergency or loss of power,  maintenance of monitors and metal detection equipment,  security for the system equipment, communications, software, and data,  training for operating personnel, and documentation requirements for authorized removals of SNM.


(3) With the individual being checked in the detection area, an alarm should sound if the activity in the detection area exceeds the alarm threshold T, as such a situation would indicate the presence of SNM. (4) The doorway monitor should be equipped with a high-background alarm which will sound if the measurement of background exceeds the appropriate maximum permissible background level listed in Table II as determined in Appendix C. The doorway monitor should not be used during such periods of high back ground.  b. Unattended Doorway Monitor (1) If the doorway monitor is unattended, an automatic background update system should be incor porated into the doorway monitor electronics and alarm logic. The control circuitry, if possible, should be located at the central alarm station (or other monitoring point).  (2) Door interlocks and closed-circuit TV in combination with beam breaks, motion detectors, and/ or treadle pads, should be employed to: (a) Indicate to the person manning the central alarm station that an individual has entered the secure access passageway and/or is approaching the doorway monitor, (b) Allow observation of the individual ap proaching the doorway monitor, (c) Preclude a slow approach to the sensitive area of the doorway monitor, and *By use is meant an individual or several individuals, each, in turn, being checked for SNM by the doorway monitor. The maximum period between threshold sets while the doorway monitor is in use is determined by the stability of local background and may necessarily be more frequent than every 15 minutes.(d) Activate the electronics and alarm logic when an individual is within the detection area and initiate operation of the doorway monitor.
==D. IMPLEMENTATION==
The purpose of this section is to provide information on how applicants and licensees
4 may use this guide and information regarding the NRC's plans for using this RG.  In addition, it describes how the NRC staff complies with the Backfit Rule found in
10 CFR 50.109(a)(1), 10 CFR 70.76(a)(1), and 10 CFR 76.76(a)(1) or any applicable finality provisions in
10 CFR Part 52. Use by Applicants and Licensees Applicants and licensees may voluntarily
5 use the guidance in this document to demonstrate compliance with the underlying NRC regulations. Methods or solutions that differ from those described in this RG may be deemed acceptable if they provide sufficient basis and information for the NRC staff to verify that the proposed alternative demonstrates compliance with the appropriate NRC regulations.


(3) An alarm should sound in the central alarm station if, when occupied, the activity in the detection area exceeds the internally set threshold level (the mean background plus some multiple times the square root of the mean background), as such a situation would indicate the presence of SNM upon the individual being checked.
Current licensees may continue to use guidance the NRC found acceptable for complying with the identified regulations as long as their current licensing basis remains unchanged.  The acceptable guidance may be a previous version of this RG.  Licensees may use the information in this RG for actions which do not require NRC review and approval.  However, voluntarily using the subject matter in the guidance may change the facilities


(4) The doorway monitor should be equipped with a high-background alarm which will sound if the average background at the location of the doorway monitor exceeds the appropriate maximum permissible background level listed in Table II as determined in Appendix C. The doorway monitor should not be used during such periods of high background.
4  In this section, "licensees" refers to holders of, and the term "applicants" refers to applicants for, the following: (1) special nuclear material licenses under
10 CFR Part 70; (2) operating licenses under
10 CFR Part 50; (3) combined licenses under
10 CFR Part 52;  and (4) certificates of compliance or approvals of a compliance plan for gaseous diffusion plants under
10 CFR Part 76.


Other moni tored exits should be used. 3. Testing and Calibration a. Testing Doorway monitors should be tested by passing an appropriate source of the amount and isotope specified in Regulatory Position C.l.b. through the doorway monitor no less frequently than once per day.* In addition, a functional performance test should be carried out at least once per week. An acceptable functional performance test procedure is discussed in Appendix A of this guide b. Calibration Doorway monitors should be calibrated with a source of the amount, configuration, and variety of SNM to be detected (e.g., 0.5 gram Pu in 3 mm of brass).  Calibration should be carried out according to a proce dure such as that in Appendix B.  c. Operating Instructions Operating instructions should be posted near the doorway monitor,*
5 In this section, "voluntary" and "voluntarily" means that the licensee is seeking the action of its own accord, without the force of a legally binding requirement or an NRC representation of further licensing or enforcement action.
if attended, or at the monitoring point if the doorway monitor is unattended.


The instructions should clearly indicate the procedure for use of the doorway monitor and the procedure for setting thresholds, if appropriate.
RG 5.27, Rev. 1, Page 12  security plan such that NRC review may be required under the provisions of
10 CFR Part 50.54, 10 CFR Part 70.32 or
10 CFR Part 76.68, and should be evaluated prior to incorporating the methods into the security plans.  Licensees may use the information in this RG or applicable parts to resolve regulatory or inspection issues.


In addition, the operating instructions should indicate what corrective action is to be taken and who is to be notified in the event of a malfunction.
Use by NRC Staff The NRC staff does not intend or approve any imposition or backfitting of the guidance in this RG.  The NRC staff does not expect any existing licensee to use or commit to using the guidance in this RG, unless the licensee makes a change to its licensing basis.  The NRC staff does not expect or plan to request licensees to voluntarily adopt this RG to resolve a generic regulatory issue.  The NRC staff does not expect or plan to initiate NRC regulatory action which would require the use of this RG.  Examples of such unplanned NRC regulatory actions include issuance of an order requiring the use of the RG, generic communication, or promulgation of a rule requiring the use of this RG without further backfit consideration.


*Doorway monitors used to search for concealed U-233 should be tested according to §6 of Appendix A.5.27-3 TABLE I ALARM THRESHOLD
During regulatory discussions on plant specific operational issues, the staff may discuss with licensees various actions consistent with staff positions in this RG, as one acceptable means of meeting the underlying NRC regulatory requirement.  Such discussions would not ordinarily be considered backfitting even if prior versions of this RG are part of the licensing basis of the facility.  However, unless this RG is part of the licensing basis for a facility, the staff may not represent to the licensee that the licensee's failure to comply with the positions in this RG constitutes a violation.
T B n= 4 5 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860 880 900 920 940 960 980 6 140 164 .187 211 234 257 279 302 324 347 369 392 414 436 458 480 502 524 546 568 589 611 633 655 676 698 720 741 763 784 806 827 849 870 892 913 935 956 977 999 1020 1041 1063 1084 1105 5.27-4 7 8 150 175 199 223 247 271 294 317 341 364 387 409 432 455 477 500 522 545 567 590 612 634 656 678 700 722 744 766 788 810 832 854 876 898 920 941 963 985 1007 1028 1050 1072 1093 1115 1137 160 186 211 236 260 285 309 333 357 380 404 427 451 474 497 520 543 566 589 611 634 657 679 702 724 747 769 792 814 836 859 881 903 925 948 970 992 1014 1036 1058 1080 1102 1124 1146 1168 170 197 223 249 274 299 324 348 373 397 421 445 469 493 516 540 563 587 610 633 657 680 703 726 749 771 794 817 840 863 885 908 930 953 975 998 1020 1043 1065 1088 1110 1132 1155 1177 1199 180 208 235 261 287 313 339 364 389 414 439 463 488 512 536 560 584 608 632 655 679 702 726 749 773 796 819 842 866 889 912 935 958 981 1003 1026 1049 1072 1095 1117 1140 1163 1185 1208 1230 9 190 219 246 274 301 327 353 379 405 431 456 481 506 531 555 580 604 629 653 677 701 725 749 773 797 820 844 868 891 915 938 961 985 1008 1031 1055 1078 1101 1124 1147 1170 1193 1216 1239 1262 10 200 230 258 286 314 341 368 395 421 447 473 499 524 550 575 600 625 650 674 699 724 748 772 797 821 845 869 893 917 941 965 988 1012 1036 1059 1083 1106 1130 1153 1177 1200 1223 1247 1270 1293 TABLE I (Cont'd) ALARM THRESHOLD
T B n = 4 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 9600 9800 1126 1339 1550 1760 1970 2179 2388 2596 2804 3012 3219 3426 3633 3840 4047 4253 4459 4665 4871 5077 5283 5483 5694 5899 6105 6310 6515 6720 6925 7130 7335 7539 7744 7949 8153 8358 8562 8767 8971 9175 9379 9584 9788 9992 10196 5 1158 1373 1587 1800 2012 2224 2435 2645 2855 3065 3274 3483 3692 3900 4108 4316 4524 4732 4939 5146 5354 5561 5767 5974 6181 6387 6594 6800 7006 7212 7418 7624 7830 8036 8242 8447 8653 8858 9064 9269 9474 9680 9885 10090 10295 5.27-5 9 6 1190 1408 1624 1840 2055 2268 2481 2694 2906 3117 3329 3539 3750 3960 4170 4379 4589 4798 5007 5216 5424 5633 5841 6049 6257 6465 6672 6880 7087 7295 7502 7709 7916 8123 8330 8537 8743 8950 9156 9363 9569 9775 9932 10188 10394 7 1221 1442 1662 1880 2097 2313 2528 2743 2957 3170 3383 3596 3808 4020 4232 4443 4654 4864 5075 5285 5495 5705 5914 6124 6333 6542 6751 6960 7169 7377 7586 7794 8002 8210 8418 8626 8834 9042 9249 9457 9664 9871 10079 10286 10493 8 1253 1477 1699 1920 2139 2358 2575 2792 3008 3223 3438 3653 3866 4080 4293 4506 4718 4931 5143 5354 5566 5777 5988 6199 6409 6620 6830 7040 7250 7460 7669 7879 8088 8297 8507 8716 8924 9133 9342 9550 9759 9967 10176 10384 10592 1285 1512 1737 1960 2182 2402 2622 2841 3059 3276 3493 3709 3925 4140 4355 4569 4783 4997 5210 5424 5636 5849 6061 6273 6485 6697 6909 7120 7331 7542 7753 7964 8174 8385 8595 8805 9015 9225 9435 9644 9854 10063 10273 10482 10691 1316 1546 1774 2000 2224 2447 2669 289C 3110 3329 3548 3766 3983 4200 4416 4632 4848 5063 5278 5493 5707 5921 6135 6348 6562 6775 6987 7200 7412 7625 7837 8049 8260 8472 8683 8894 9106 9317 9527 9738 9949 10159 10370 10580 10790
TABLE II MAXIMUM PERMISSIBLE
BACKGROUND
a = 0, Pa = 50%B n= 4 100 120 140 160 180.  200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860 880 900 920 940 960 980 5 67 83 100 117 134 151 168 186 203 221 238 256 274 292 310 328 346 364 382 400 418 436 455 473 491 510 528 546 565 583 602 620 639 657 676 695 713 732 750 769 788 806 825 844 863 G 61 76 92 108 124 141 157 174 191 208 225 242 259 277 294 312 329 347 365 382 400 418 436 454 471 489 507 525 543 562 580 598 616 634 652 671 689 707 725 744 762 780 799 817 835 6 55 70 85 100 116 131 147 163 180 196 213 229 246 263 280 297 314 331 348 365 383 400 417 435 452 470 488 505 523 541 558 576 594 612 629 647 665 683 701 719 737 755 773 791 809 5.27-6 7 50 64 78 93 107 123 138 153 169 185 201 217 233 249 266 282 299 316 332 349 366 383 400 417 434 451 468 486 503 520 538 555 573 590 607 625 643 660 678 695 713 731 748 766 784 9 10 8 46 59 72 86 100 114 129 144 159 174 190 205 221 237 253 269 285 301 317 334 350 367 383 400 417 433 450 467 484 501 518 535 552 569 586 603 621 638 655 673 690 707 725 742 760 42 54 67 80 93 107 121 135 150 165 179 194 210 225 240 256 272 287 303 319 335 351 367 384 400 416 433 449 466 482 499 516 532 549 566 583 600 617 633 650 667 685 702 719 736 38 50 62 74 87 100 113 127 141 155 170 184 199 214 229 244 259 274 290 305 321 337 352 368 384 400 416 432 448 464 481 497 513 530 546 563 579 596 613 629 646 663 679 696 713 TABLE II (Cont'd)MAXIMUM PERMISSIBLE
BACKGROUND
B G n = 4 1000 1200 1400 1600 1000 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 9600 9800 881 1069 1258 1448 1638 1829 2020 2212 2404 2596 2789 29S2 3175 3368 3561 3755 3949 4143 4337 4531 4725 4919 5114 5309 5503 5698 5893 6088 6283 6478 6673 6868 7064 7259 7455 7650 7846 8041 8237 8433 8628 8824 9020 9216 9412 5 854 1039 1225 1412 1600 1789 1978 2167 2357 2548 2738 2929 3121 3312 3504 3696 3888 4081 4273 4466 4659 4852 5045 5238 5432 5625' 5819 6012 6206 6400 6594 6788 6982 7176 7371 7565 7760 7954 8149 8343 8538 8733 8928 9122 9317 a -'0, Pa = 50Z 6 827 1009 1193 1377 1563 1749 1936 2124 2312 2500 2689 2878 3068 3258 3448 3638 3829 4020 4211 4402 4593 4785 4977 5169 5361 5553 5745 5938 6130 6323 6516 6709 6902 7095 7288 7481 7674 7868 8061 8255 8449 8642 8836 9030 9224 7 802 981 1161 1343 1527 1710 1895 2081 2267 2453 2640 2828 3016 3204 3392 3581 3770 3960 4149 4339 4529 4719 4910 5100 5291 5482 5673 5864 6055 6247 6438 6630 6822 7014 7206 7398 7590 7782 7975 8167 8360 8553 8745 8938 9131 8 777 953 1131 1310 1491 1673 1855 2039 2223 2407 2593 2778 2964 3151 3338 3525 3713 3900 4088 4277 4465 4654 4843 5032 5222 5411 5601 5791 5981 6172 6362 6552 6743 6934 7125 7316 7507 7698 7889 8081 8272 8464 8656 8348 9039 5.27-7 9 753 926 1101 1278 1457 1636 1816 199D 2180 2363 2546 2730 2914 3099 3284 3470 3656 3842 4029 4216 4403 4590 4778 4966 5154 5342 5531 5719 5908 60'97 6286 6476 6665 6855 7045 7234 7425 7615 7805 7995 8186 8376 8567 8758 8949 10 730 900 1073 1247 1423 1600 1778 1958 2138 2318 2500 2682 2865 3048 3232 3416 3600 3785 3970 4155 4341 4527 4713 4900 5087 5274 5461 5648 5836 6024 6212 6400 6588 6777 6965 7154 7343 7532 7721 7911 8100 8290 8479 8669 8859 TABLE II (Cont'd)MAXIMUM PERMISSIBLE
BACKGROUND
B G n 4 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800 820 840 860 880 900 920 940 960 980 57 72 87 103 119 135 151 168 185 201 218 235 252 270 287 304 322 339 357 374 392 409 427 445 463 480 498 516 534 552 570 588 606 624 642 660 679 697 715 733 751 770 788 806 824 5 51 65 80 95 110 126 141 157 173 189 206 222 239 255 272 289 306 323 340 357 374 391 409 426 443 461 478 496 513 531 549 566 584 602 619 637 655 673 690 708 726 744 762 780 798 6 46 59 73 87 102 117 132 147 163 178 194 210 226 242 258 275 291 308 324 341 357 374 391 408 425 442 459 476 493 511 528 545 562 580 597 614 632 649 667 684 702 720 737 755 773 S= 1.3, Pa = 90%7 42 54 67 81 95 109 123 138 153 168 183 198 214 229 245 261 277 293 309 325 342 358 374 391 407 424 441 457 474 491 508 525 542 559 576 593 610 627 644 661 679 696 713 731 748 9 8 38 49 62 75 88 101 115 129 143 158 172 187 202 217 233 248 263 279 295 311 326 342 358 374 391 407 423 439 456 472 489 505 522 539 555 572 589 605 622 639 656 673 690 707 724 5.27-8 34 45 57 69 81 94 107 121 135 149 163 177 191 206 221 236 251 266 281 297 312 327 343 359 375 390 406 422 438 454 470 487 503 519 535 552 568 585 601 618 634 651 668 684 701 10 31 41 52 64 76 FS 100 113 127 1L0 154 167 181 196 210 224 22S 254 268 283 298 313 329 344 359 375 390 406 421 437 453 469 485 500 516 532 549 565 581 597 613 630 646 662 679 TABLE II (Cont'd)MAXIMUM PERMISSIBLE
BACKGROUND
G n= 4 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 3800 4000 4200 4400 4600 4800 5000 5200 5400 5600 5S00 6000 6200 6400 6600 6800 7000 7200 7400 7600 7800 8000 8200 8400 8600 8800 9000 9200 9400 9600 98-00 843 1027 1212 1398 1536 1773 1962 2151 2340 2530 2720 2911 3101 3292 3484 3675 3867 4059 4251 4443 4636 4828 5021 5214 5407 5600 5793 5987 6180 6373 6567 6761 r9955 7148 7342 7536 7731 7925 8119 3313 8508 8702 8897 9091 9286 5 816 997 1180 1363 it48 1734 1920 2107 2294 2482 2670 2859 3048 3238 3427 3617 3807 3998 4188 4379 4570 4761 4953 5144 5336 5528 5720 5912 6104 6296 6488 6681 6874 7066 7259 7452 7645 7838 8031 8225 8418 8611 8805 8998 9192 6 790 968 1148 1329 1512 1695 1879 2064 2249 2435 2622 2808 2996 3183 3371 3560 3748 3937 4126 4316 4505 4695 4885 5075 5266 5456 5647 5S38 6029 6220 6411 6602 6794 6985 7177 7369 7561 7753 7945 8137 8329 8521 8714 8906 9099 5.27-9 a = 1.3, P= = 90%7 765 940 1117 1296 1476 1657 1839 2022 2205 2389 2574 2759 2944 3130 3317 3503 3691 3878 4066 4253 4442 4630 4819 5007 5196 5386 5575 5765 5954 6144 6334 6524 6715 6905 7096 7286 7477 7668 7859 8050 8241 8433 8624 8815 9007 8 741 913 1088 1264 1441 1620 1800 1980 2162 2344 2527 2710 2894 3078 3263 3448 3634 3319 4006 4192 4379 4566 4753 4940 5128 5316 5504 5692 5831 6070 6258 6447 6636 6826 7015 7205 7394 7584 7774 7964 8154 8345 8535 8725 8916 9 718 887 1059 1232 1407 1584 1761 1940 2119 2300 2481 2662 2844 3027 3210 3393 3577 3762 3946 4131 4317 4502 4688 4874 5061 5247 5434 5621 580G 5996 6184 6371 6559 6747 6936 7124 7313 7501 7690 7879 8063 8257 8447 8636 8826 10 695 861 1030 1201 1374 1548 1724 1900 2078 2256 2435 2615 2795 2976 3158 3340 3522 3705 3888 4072 4256 4440 4624 4809: 4994 5180 5365 5551 5737 5923 6110 6296 6483 6670 6857 7044 7232 7419 7607 7795 7983 8171 8360 8548 8737 APPENDIX A PROCEDURE
FOR TESTING SNM DOORWAY MONITORS FOR FUNCTIONAL
PERFORMANCE
Doorway monitors should be tested by employing a test source of the same isotope of SNM the doorway monitor is used to detect as follows: 1. With the detection area unoccupied, measure and record background.


2. Determine alarm threshold T from Table I (see Appendix B). 3. Place a test source in the detection area of the doorway monitor. The test source should be such that the activity in the detection area slightly exceeds the T level.* The doorway monitor should go into an alarm condition if operating properly.
If an existing licensee voluntarily seeks a license amendment or change and (1) the NRC staff's consideration of the request involves a regulatory issue directly relevant to this revised RG and (2) the specific subject matter of this RG is an essential consideration in the staff's determination of the acceptability of the licensee's request, then the staff may request that the licensee either follow the guidance in this RG or provide an equivalent alternative process that demonstrates compliance with the underlying NRC regulatory requirements. This is not considered backfitting as defined in
10 CFR 50.109(a)(1), 10 CFR 70.76(a)(1), or 10 CFR 76.76(a)(1)
or any applicable finality provisions in
10 CFR Part 52. If a licensee believes that the NRC is either using this RG or requesting or requiring the licensee to implement the methods or processes in this RG in a manner inconsistent with the discussion in this Implementation section, then the licensee may file a backfit appeal with the NRC in accordance with the guidance in NUREG
-1409, "Backfitting Guidelines," (Ref. 18) and the NRC Management Directive 8.4, "Management of Facility
-Specific Backfitting and Information Collection" (Ref 19).       
RG 5.27, Rev. 1, Page 13  REFERENCES
6 1. U.S. Code of Federal Regulations , "Domestic Licensing of Production and Utilization Facilities
," Part 50 (10
CFR 50), Title 10, "Energy."  2. 10 CFR 52 , "Licenses, Certifications, and Approvals for Nuclear Power Plants," Title 10, "Energy"    3. 10 CFR 76, "Physical Protection of Plants and Materials," Title 10, "Energy"    4. 10 CFR 73, "Certification of Gaseous Diffusion Plants," Title 10, "Energy"    5. U.S. Nuclear Regulatory Commission (NRC), "Entry/Exit Control of Personnel Access to Protected Areas, Vital Areas, and Material Access Areas," Regulatory Guide (RG) 5.7, Washington, DC, Agencywide Document Access and Management System (ADAMS)  Accession No.


4. Remove test source to its original location and measure background once again. If the measurement of *The test source may be improvised by partially shielding the calibration source.background taken immediately after the test varies by more than 2vN from the background taken before the test, the test should be repeated, for such a difference indicates nonrandom fluctuations of the background or equipment malfunction.
ML003739976
. 6. NRC, "Access Control Systems:  Technical Information for NRC Licensees," NUREG-1964, Washington, DC. (ML1115A078)
  7. Knoll, Glenn F., "Radiation Detection and Measurement," 4th ed., John Wiley and Sons
7 , 20 10.  8. LA-UR-96-4505, "An Optimized International Vehicle Monitor," R. L. York, D. A. Close, and P. E. Fehlau, Los Alamos National Labs, Los Alamos, NM (1997).
8  9. American Society for Testing and Materials (ASTM)
C1189-11, "Standard Guide to Procedures for Calibrating Automatic Pedestrian SNM Monitors," West Conshohocken, PA.


The probability of such an occurrence due to the randomness of the background is less than 8%. 5. A calibration source (Appendix B) should be carried repeatedly to various places within the detection area of the doorway monitor in simulation of actual use to verify that the SNM can be detected everywhere within the detection area and to assure proper operation of treadle pads, beam-break, or similar devices if the doorway monitor is so equipped.
9 10. ASTM , C1112-99(2005), "Standard Guide for Application of Radiation Monitors to the Control and Physical Security of Special Nuclear Material," West Conshohocken, PA.


6. Doorway monitors used to search for concealed uranium-233 should be tested with each uranium purification run, but no more frequently than daily. The test source should be freshly purified uranium-233 (within four hours of removal of decay products).
11. ASTM C1237
5.27-10
-99(2005), "Standard Guide to In
APPENDIX B PROCEDURE
-Plant Performance Evaluation of Hand
FOR DETERMINING
-Held SNM Monitors," West Conshohocken, PA.
MAXIMUM PERMISSIBLE
BACKGROUND
Background should be measured over several work shifts to determine the setpoints for alarm threshold (with or without automatic background updating)
to assure that normal operation will be minimally affected by alarms due to high background.


The doorway monitor should be calibrated with the amount of the appropriate isotope specified in Regula tory Positions C.l.b(1), (2), or (3) of this guide (e.g., 0.5 gram plutonium-239 in 3 mm of brass).  The calibration procedure described below is essen tially a means of determining maximum permissible background for effective operation of the doorway monitor.
12. ASTM C993-97(2012), "Standard Guide for In
-Plant Performance Evaluation of Automatic Pedestrian SNM Monitors," West Conshohocken, PA.


1. Place a calibration source variously about the detec tion area and take readings to determine the least sensitive point. This location of minimum sensitivity should be maintained as the calibration point.  2. Measure background over several workshifts to deter mine the periods of high background and the range of background.
6  Publicly available NRC published documents are available electronically through the NRC Library on the NRC's public Web site at http://www.nrc.gov/reading
-rm/doc-collections/
and through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading
-rm/adams.html The documents can also be viewed online or printed for a fee in the NRC's Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD.  For problems with ADAMS, contact the PDR staff at 301
-415-4737 or (800) 397
-4209; fax (301) 415
-3548; or  e-mail pdr.resource@nrc.gov
.
7  Copies of this publication and, or current edition are available thru the Wiley website at: http://www.wiley.com/
  8  Copies of this publication are available thru the US Department of Energy, Office of Scientific and Technical Information (OSTI) website at: http://www.osti.gov/scitech/servlets/purl/444040


A minimum of 20 measurements should be taken. The variance of the background is given by N Var B 1 (Bi-B)2  (1) where N is the number of measurements, B is the mean of the background measurements, and Bi is the ith background measurement.
9  Copies of American Society for Testing and Materials (ASTM) standards may be purchased from ASTM, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA  19428
-2959; telephone 610
-832-9585. Purchase information is available through the ASTM Web site at http://www.astm.org
. 
RG 5.27, Rev. 1, Page 14  13. ASTM C1270
-97(2012), "Standard Practice for Detection Sensitivity Mapping of In
-Plant Walk Through Metal Detectors," West Conshohocken, PA.


3. With the calibration source at the calibration point, the mean gross counts G should be determined during a period of high background to establish the upper operating range of the doorway monitor. Table II lists various maximum permissible background levels for a given value of G for values of the parameters n and a.  During periods when the background exceeds the value found from Table II, the sensitivity of the doorway monitor will generally be below that specified as minimum in Regulatory Position C.l.b of this guide. The parameter n is a function of the background variation and the permissible false alarm rate and is calculated from n >3.1 (var B) 1/2 (2)Generally, n is taken as an integer. If n satisfies the above expression, the expected false alarm rate (Appen dix C) due to background fluctuations should be less than 0.1%. Larger values of n will decrease the expected false alarm rate; however, the maximum allowable background for a given G will also decrease.
14. ASTM C1270
-97(2012), "Standard Practice for Detection Sensitivity Mapping of In
-Plant Walk Through Metal Detectors," West Conshohocken, PA.  15. ASTM C1269
-97(2012), "Standard Practice for Adjusting the Operational Sensitivity Setting of In-Plant Walk
-Through Metal Detectors," West Conshohocken, PA
  16. ASTM C1309
-97(2012), "Standard Practice for Performance Evaluation of In
-Plant Walk-Through Metal Detectors," West Conshohocken, PA
  17. ASTM C1236
-99(2005), "Standard Guide for In
-Plant Performance Evaluation of Automatic Vehicle SNM Monitors," (Withdrawn 2014) West Conshohocken, PA
  18. International Atomic Energy Agency (IAEA), "IAEA Nuclear Security Series No. 13, Nuclear Security Recommendations on Physical Protection of Nuclear Material and Nuclear Facilities," Vienna, Austria, January 2011.


4. For doorway monitors equipped with automatic background updating systems, the alarm threshold is Counts > B + nVii, (3)where n should be derived from expression
10  19. NRC, "Backfitting Guidelines,"
(2), and the instrument set accordingly.
NUREG-1409 , Washington, DC. (ML032230247)
  20. NRC, "Management of Facility
-specific Backfitting and Information Collection
," Management Directive 8.4, Washington, DC.


5. The high-background alarm should be set at the B value given in Table II for the measured G and calculated n values.  6. For doorway monitors not equipped with an auto matic background update, the value of n determined above should be employed in the use of the doorway monitor according to Regulatory Position C.2.a.  *The false alarm rate is estimated by the probability that an observation of a quantity distributed normally about some value X will exceed X by n(Std. deviation of X). The factor 3.1 limits the false alarm rate to 0.1%, while the factor (Var B/B)1/2 compensates for observed deviations in the background distribution from Poisson.5.27-11 APPENDIX C DETECTION
(ML12059A460)
CONFIDENCE
LIMITS, THRESHOLDS, AND MAXIMUM PERMISSIBLE
BACKGROUND
With a calibration source at the calibration point, the condition for an alarm is, in general, g> T = B + m/Va' B (1) where g is a single measurement of G (the mean radiation level with the source), B is the mean back ground, and m is some multiplier.


The detection confidence limit is the probability that with the calibra iton source at the calibration point, any single determin ation of G will exceed a threshold T, i.e., the above inequality will be satisfied.
10  Copies of International Atomic Energy Agency (IAEA) documents may be obtained through their Web site: WWW.IAEA.Org/
or by writing the International Atomic Energy Agency P.O. Box 100 Wagramer Strasse 5, A
-1400 Vienna, Austria. Telephone (+431) 2600
-0, Fax (+431) 2600
-7, or E-Mail at Official.Mail@IAEA.Org


For any given probability Pa., there exists a value a such that g > G- (2) with a probability of Pa, where g is any single measure ment of the quantity G. Hence the condition for a detection confidence limit of Pais G -& > T = B + m,,/'r B. (3) For a given value of G, solving (3) gives the maximum permissible B at which the doorway monitor will detect the source with a confidence Pr- For Pa = 90%, a = 1.3, and for Pa = 50%, a = 0.The condition for a false alarm* is written as b = B + j a-'"B> T (4)where b is a single measurement without the source and 0 is a number corresponding to a false alarm probability Pp. For P = 0.1%, 0 = 3.1. Hence the necessary condition for maintaining a false alarm rate below Pp is b = B + -"B < B + m ar. (5) However, the doorway monitor actually compares b with B + ni, hence the condition on n becomes orV < rn'VaTr = nvff (6) or n>0 ( Va B ) 1/2 (7)In Table I threshold values of T were determined by substituting equation (6) into equation (3): T = B + nv'r The values of B in Table II were then calculated for a = 1.3 and a = 0 from equation (3) assuming that, for the determination of G, the background should be reasonably stable and therefore
RG 5.27, Rev. 1, Page 15}}
\/Var G -\ *False alarm means an alarm condition generated by statistical fluctuations in the background radiation or by instabilities of the electronics which appear as background fluctuations when the detection area is occupied.5.27-12}}


{{RG-Nav}}
{{RG-Nav}}

Revision as of 17:52, 14 July 2019

Rev. 1, Special Nuclear Material Doorway Monitors
ML14290A268
Person / Time
Issue date: 07/23/2015
From: Al Tardiff
Office of Nuclear Security and Incident Response
To:
Jervey R
References
DG-5038 RG-5.027 Rev 1
Download: ML14290A268 (14)
v • d • e


U.S. NUCLEAR REGULATORY COMMISSION

July 2015 OFFICE OF NUCLEAR REGULATORY RESEARCH

Revision 1 REGULATORY GUIDE

Technical Lead A. Tardiff Written suggestions regarding this guide or development of new guides may be submitted through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading

-rm/doc-collections/reg

-guides/contactus.html

. Electronic copies of this regulatory guide, previous versions of this guide, and other recently issued guides are available through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading

-rm/doc-collections/. The regulatory guide is also available through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading

-rm/adams.html, under ADAMS Accession No.

ML14290A268. The regulatory analysis may be found in ADAMS under Accession No. ML12237A124 and the staff responses to the public comments on DG

-5038 may be found under ADAMS Accession No. ML14288A653. REGULATORY GUIDE 5.27 (Draft was issued as DG

-5038, dated March 2014)

SPECIAL NUCLEAR MATERIAL DOORWAY MONITORS

A. INTRODUCTION

Purpose The U.S. Nuclear Regulatory Commission (NRC) developed this regulatory guide (RG) to describe a method that the NRC staff considers acceptable to implement the search requirement for concealed special nuclear material (SNM) applied to personnel, vehicles, packages and all other materials exiting a material access area (MAA).

For holders of a reactor license under Title 10 of the Code of Federal Regulations (10 CFR)

Part 50, "Domestic Licensing of Production and Utilization Facilities" (Ref. 1), a combined license under

10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants" (Ref. 2), or a fuel cycle facility license under

10 CFR Part 76, "Certification of Gaseous Diffusion Plants" (Ref. 3), having the need to possess or use SNM within their facility, the NRC typically has included in their license a condition granting a general license to use SNM under

10 CFR Part 70, "Domestic Licensing of Special Nuclear Material."

Applicable Rules and Regulations The requirements for physical protection found within

10 CFR Parts 50, 52, 70, and 76 refer to the physical protection requirements of

10 CFR Part 73, "Physical Protection of Plants and Materials." Part 73 (Ref. 4) requires, in part, in

10 CFR 73.46(d)(9) and

10 CFR 73.60(b), that each individual , package, materials and vehicle exiting an MAA is searched for concealed SNM. Specific testing and maintenance requirements, as stated in

10 CFR 73.20(b)(4), 10 CFR 73.46(g), and

10 CFR 73.60(d)(1) also apply.

Related Guidance Regulatory Guide 5.7, "Entry/Exit Control of Personnel Access to Protected Areas, Vital Areas, and Material Access Areas"

(Ref. 5) NUREG 1964, "Access Control Systems: Technical Information for NRC Licensees" (Ref. 6)

RG 5.27, Rev. 1, Page 2 Purpose of Regulatory Guides The NRC issues RGs to describe to the public methods that the staff considers acceptable for use in implementing specific parts of the agency

's regulations, to explain techniques that the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to applicants. Regulatory guides are not substitutes for regulations and compliance with them is not required.

Methods and solutions that differ from those set forth in RGs will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a permit or license by the Commission.

Information Collection Requirements This RG contains information collection requirements covered by

10 CFR Part 73 , "Physical Protection of Plants and Materials,"

that the Office of Management and Budget (OMB) approved under OMB control number 3150

-0002. The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control number.

B. DISCUSSION

Reason for Revision This RG is being revised because it was out

-of-date with current related guidance and references in the CFR. Related specifications and standards for SNM monitors and metal detectors have been updated or developed since the previous revision was issued in 1974.

This revision has been developed to provide detection practices and criteria that licensees may use to demonstrate compliance with NRC regulations in

10 CFR Part 73 and to augment programmatic information within the general reference, NUREG-1964, "Access Control Systems: Technical Information for NRC Licensees," (Ref. 6) issued in April of 2011

. Background

Special nuclear material doorway monitors provide an efficient, sensitive, and reasonably unobtrusive way of searching individuals for concealed SNM

upon exit from an MAA. With proper installation and operation, gram quantities or less of SNM can be detected with a high level of reliability while maintaining a low false alarm rat

e. Portal type walk

-through metal detectors are often used in conjunction with radiation detection to assure that personnel entering or leaving MAAs are screened for metallic nuclear shielding materials.

Theory of Operation The doorway monitor comprises one or more detector unit(s), associated electronics, and alarm logic. The detector units are sensitive to the SNM radiation and responds to the emitted radiation (gamma rays and neutrons) by generating electronic current pulses. These pulses are amplified, filtered, and fed to alarm logic circuits that interpret the number (or rate) of pulses during a sampling. The alarm logic may be either a digital or analog system. In either case, if the rate of pulses exceed a set level, the alarm is triggered. Additional information pertaining to detector theory can be found in Knoll's, "Radiation Detection and Measurement." (Ref.7)

RG 5.27, Rev. 1, Page 3 General Characteristics Doorway Monitors Doorway monitors detect gamma

-ray radiation using scintillation or semiconductor detectors. To detect neutrons, plastic scintillators or gas

-filled proportional counters are use

d. Geiger

-Mueller counters have been used in this application; however, their lower intrinsic efficiency renders them less suitable than scintillation detectors. Scintillation detectors are often used for discriminating pulses based o n imparted energy. Plastic scintillation detectors have the advantage of responding well to gamma

-ray and energetic neutrons whereas the sodium iodide thallium

-activated NaI(Tl) scintillation detectors have good gamma-ray sensitivity but poor neutron respons

e. Helium

-3 (He-3) gas is used in tubes as a proportional counter for neutron detection. The trend in industry is to use both scintillation detectors and He-3 detectors for doorway monitor systems.

Detectors are arranged so that a detection area is defined by a plane perpendicular to the line of passage of individuals through the doorway monitor. Various arrangements of the detectors are possible.

However, specific placement of detectors should be based on the need to eliminate areas of no detection

. Commercially available doorway monitors are equipped with an automatic radiation background updating system that periodically monitors and averages the background count rate. A doorway monitor equipped with an automatic radiation background updating system is also provided with a treadle pad or beam break system to indicate that the zone of detection is occupied. When the zone of detection is occupied, the radiation level detected by the doorway monitor is compared to the mean background. If the level is greater than the mean background by a predetermined trigger level, an alarm is actuated. Alarm actuation point is usually determined by comparing the radiation levels within the zone of detection while occupied to the sum of the mean background while unoccupied and a factor to account for predetermined statistical accuracy

.1 Thus, the condition for an alarm can be written as

G>B+n(B) 1/2 Where B is the mean background, G is the radiation level within the zone of detection while occupied and n is a multiplier, usually between 4 and 10.

2 Although the automatic background updating system allows unattended use of the doorway monitor, for technical reasons, the system may be less effective in certain situations. Techniques to prevent this are provided in the regulatory position.

Whether or not a doorway monitor is equipped with an automatic background updating system, high background activity will decrease sensitivity. Measuring activity in the zone of detection for longer

1 The square root of the mean of a Poisson

-distributed quantity is the unbiased estimate of the standard deviation of that quantity. 2 Note that, in general, for a count rate system, the condition for alarm should be modified to account for the response time of the instrument as follows:

G>B+n(B)1/2 (1-e-t/r) Where t is the counting time and r is the time constant of the instrument. If, as should be the case, t/r>5, the added factor is essentially unity.

RG 5.27, Rev. 1, Page 4 periods of time will compensate somewhat for a high radiation background. However, longer measurement periods can make the use of the doorway monitor less convenient. Because of the adequate radiation detection sensitivity and high

-throughput capability associated with processing many personnel through the detection system on a daily basis, walk

-through pedestrian monitors are the primary SNM detection system used in personnel portals at MAAs.

Hand-Held Monitors Hand-held monitors can use detectors made of NaI(Tl), plastic scintillators, semiconductors, or He-3 gas-filled tubes. Commercially available systems have rechargeable batteries that assist in ensuring continuous availability. Training the operator of a hand

-held monitor is essential. The operator must scan an individual in the correct way for a hand

-held monitor to be fully effective. In addition, the operator must understand the capabilities of the equipment, when the equipment is working within acceptable parameters and when it is not.

Radioisotope identification systems that detect radiation with high purity germanium (HPGe) detectors can be hand

-held. These monitors are commercially available and may have a special cooling device, instead of a cryogenic bath, to cool the semiconductor HPGe crystal. Special cooling devices (e.g., Stirling cooler) allow a light

-weight design useful as a hand held detection system.

Hand-held monitors complement SNM search operations by enabling a more thorough search of an individual to locate the radiation source after a doorway monitor has alarmed, enabling pedestrian searches to continue when a doorway monitor is inoperative and, if technically outfitted to do so, identify specific radionuclide(s) causing a doorway alarm.

Because of the time required to scan an individual with a hand-held monitor, it is used as a secondary SNM detection system at an MAA personnel portal.

Vehicle Monitors

Two types of automatic vehicle monitors presently in use are the vehicle monitoring station and the drive-through vehicle monitor. Commercially available vehicle drive

-through SNM portals generally consist of two vertical cabinets containing both large plastic scintillators and decision

-making electronics. These scintillators continuously measure the gamma ray background intensity and adjust the alarm threshold to maintain a constant nuisance alarm rate. The sensitivity of SNM vehicle monitors var y for different types of vehicles and depends on the size, spacing, and number of detectors. For an individual detector configuration and vehicle, two of the dominate sensitivity factors are the occupancy background suppression and shielding provided by the components of the vehicle.

3 Standards Associated with Monitoring

Selection of equipment, setup, operation calibration, testing and performance evaluation of portal monitoring systems should be performed using procedures designed for the specific facility and configuration. Guidance that pertains to the use of radiation detection and metal detection instrumentation is available from several standards organizations. The NRC staff finds that the following guidance , which has been successfully used by SNM licensees and is available from the American Society for Testing and Materials (ASTM), Conshohocken, Pennsylvania, acceptable for use:

3 LA-UR-96-4505: "An Optimized International Vehicle Monitor," (Ref. 8)

RG 5.27, Rev. 1, Page 5 ASTM C1189

-11, "Standard Guide to Procedures for Calibrating Automatic Pedestrian SNM Monitors." (Ref.

9) ASTM C1112

-99 (2005), "Standard Guide for Application of Radiation Monitors to the Control and Physical Security of Special Nuclear Material." (Ref.

10) ASTM C1237

-99 (2005), "Standard Guide to In

-Plant Performance Evaluation of Hand

-Held SNM Monitors." (Ref.

11) ASTM C993-97 (2012), "Standard Guide for In

-Plant Performance Evaluation of Automatic Pedestrian SNM Monitors." (Ref. 1

2) ASTM C1270

-97 (2012), "Standard Practice for Detection Sensitivity Mapping of In

-Plant Walk Through Metal Detectors." (Ref. 1

3) ASTM C1269

-97 (2012), "Standard Practice for Adjusting the Operational Sensitivity Setting of In

-Plant Walk

-Through Metal Detectors." (Ref. 1

4) ASTM C1309

-97 (2012), "Standard Practice for Performance Evaluation of In

-Plant Walk-Through Metal Detectors." (Ref. 1

5) In addition, ASTM C1236

-99 (2005), Standard Guide for In

-Plant Performance Evaluation of Automatic Vehicle SNM Monitors (Ref. 16) was withdrawn in 2014, but can be used by licensees as a development tool.

Harmonization with International Standards The International Atomic Energy Agency (IAEA) has established a series of safety guides and standards constituting a high level of safety for protecting people and the environment. IAEA safety guides present international good practices and increasingly reflects best practices to help users striving to achieve high levels of safety. Pertinent to this RG, "IAEA Nuclear Security Series No. 13, Nuclear Security Recommendations on Physical Protection of Nuclear Material and Nuclear Facilities," issued January 2011, (Ref. 17) et. al., addresses considerations necessary for a nuclear material security program. While the NRC has an interest in facilitating the harmonization of standards used domestically and internationally, the NRC does not specifically endorse the IAEA document, and is only acknowledging that it may be useful as a reference for general information.

RG 5.27, Rev. 1, Page 6 Documents Discussed in Staff Regulatory Guidance This RG endorses the use of one or more codes or standards developed by external organizations, and other third party guidance documents.

These codes, standards and third party guidance documents may contain references to other codes, standards or third party guidance documents ("secondary references").

If a secondary reference has itself been incorporated by reference into NRC regulations as a requirement, then licensees and applicants must comply with that standard as set forth in the regulation.

If the secondary reference has been endorsed in a RG as an acceptable approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC staff for meeting that regulatory requirement as described in the specific RG. If the secondary reference has neither been incorporated by reference into NRC regulations nor endorsed in a RG, then the secondary reference is neither a legally

-binding requirement nor a "generic" NRC approval as an acceptable approach for meeting an NRC requirement.

However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified and consistent with current regulatory practice, consistent with applicable NRC requirements such as

10 CFR 50.59. C. STAFF REGULATORY GUIDANCE

1. Considerations for SNM Doorway Monitors a. General (1) Metal detectors should be used in conjunction with an SNM doorway monitor as an SNM detection system and can be one of the two required separate searches for concealed SNM (10 CFR 73.46(d)(9)). The metal detector unit should be installed in the pedestrian passageway as described in RG 5.7, "Entry/Exit Control of Personnel Access to Protected Areas, Vital Areas, and Material Access Areas" with the SNM monitor in such a way that objects cannot be passed over, around, or under the detection area without being appropriately searched. The entire process begins when the individual, package, or other item approaches the monitoring area and ends when the individual, package or other item is exiting the monitoring area after the completion of a monitoring event.

(2) Alarm actuation for detectable metal mass should be the amount necessary to shield SNM that would allow a protracted theft of a formula quantity of strategic SNM to occur before the inventory process identifies it as missing

. (3) The detector elements should be designed and positioned so that detection sensitivity is as uniform as possible over the zone of detection; in no case should any area within the zone of detection not be able to detect SNM.

(4) Power, sensitivity, and other controls of the doorway monitor and metal detector should be tamper-safe when unattended.

Doorway monitors and metal detectors that are secured behind locked and alarmed doors when unattended is an acceptable alternative measure to implementing tamper

- safe devices on the SNM monitoring system. (5) Metal and SNM detection equipment should be provided with uninterruptible power sources and/or emergency generator power.

(6) Signal lines connecting alarm relays to the alarm monitors for both metal and SNM

detectors should be supervised electronically or by direct surveillance to detect tampering.

RG 5.27, Rev. 1, Page 7 (7) Some doorway monitors may require an individual to occupy the detection area for a specified time (e.g., longer than what a normal walking pace would provide). In this case, the doorway monitor should be provided with a treadle pad and a timer to ensure that the zone of detection is occupied for the requisite time. Audible and visual alarms should actuate if the individual being searched does not occupy the detection area for the entire count period. (8) The doorway monitor should be equipped with a high

-background radiation alarm, which will announce if the measurement of the radiation background exceeds the appropriate maximum permissible background. The doorway monitor should not be used during periods of high background radiation. Calibration and determination of allowable background thresholds should be done in accordance with ASTM C1189-11, (Ref. 9) (9) System specifications guidance for specific radioisotopes are identified below. See ASTM C1112

-99(2005), (Ref. 10) for supporting information.

(a) Plutonium-239. A doorway monitor used to detect plutonium (Pu) should be capable of detecting 0.5grams of plutonium with an isotopic content of at least

93 percent Pu

-239 and less than 6.5 percent Pu

-240. The Pu should contain less than 0.5 percent impurities. The form of the material should be a metallic sphere or cub

e. The impact of Am

-241, a Pu decay product that will build up over time and emit increasing amounts of 60

-keV gamma radiation, must be minimized by including a cadmium filter 0.04 cm to 0.08 cm thick as part of the source encapsulation. Protective encapsulation should be in as many layers as local rulecm thickness) stainless steel or nickel that minimize unnecessary radiation absorption. The source should be encased in a minimum of 3 mm brass and detected at a 50

percent probability of detection with a 95 percent confidence limit. The false alarm rate should be less than 0.1 percent. (b) Uranium-235. A doorway monitor used to detect uranium

-235 (U-235) should be capable of detecting highly enriched (i.e., 20

percent or more) uranium containing at least 93 percent U-235 and less than 0.25 percent impurities. The form of the material should be a metallic sphere or cube

. Encapsulation should be applied in such manner that it minimizes unnecessary radiation absorption in the encapsulation. The source should be encased in a minimum of 3 mm brass and detected at a 50

percent probability of detection with a 95 percent confidence limit. The false alarm rate should be less than 0.1 percent. (c) Uranium-233. Adequate sensitivity for uranium-233 (U-233) may be demonstrated by meeting the detection requirements for U

-235.

RG 5.27, Rev. 1, Page 8 2. Operations with Doorway and Hand

-Held Monitors In general, doorway monitors are the primary method used to search for concealed SNM, hand-held monitors are secondary, and a physical search is tertiary. Doorway monitors should be used in locations with minimum background radiation and minimum background radiation fluctuation. If circumstances dictate the use of a doorway monitor in an area of high background radiation, sufficient shielding should be provided to maintain necessary sensitivity.

a. The procedures, or changes to procedures developed to implement requirements of

10 CFR 73.46 should be prepared sufficiently in advance of intended implementation to provide verification of satisfactory performance.

b. The plan for metal detection equipment functionality and performance testing periodicity, procedures, and test sources should be submitted to the NRC for approval within

360 days for licensed operating facilities, 180

days before revising existing licensee SNM search programs, and 180 days before initial start of operations for newly licensed facilities.

c. During use, the doorway monitor system should check the radiation background and adjust the measurement offset at least every 15 minutes.

d. Doorway monitors shall be attended by two armed guards at an MAA (10 CFR 73.46 (d)(9)) within a facility containing a formula quantity of strategic SNM. The two armed guards may consist of a guard manning the SNM monitoring system and the other providing oversight of the SNM monitoring system activities by residing in an adjacent protective enclosure.

Doorway monitors should be attended at non

-power reactors.

e. Each individual to be checked should, in turn, enter the doorway monitor detection area and be required to remain still long enough for the device to operate properly.

f. With the individual in the doorway monitor detection area, an alarm should audibly and visually announce in the vicinity of the monitor if the activity in the detection area exceeds the set alarm threshold for radiation, possibly indicating the presence of SNM.

g. When a doorway monitor signals an alarm, the individual generating the alarm should pass through the monitor a second time to confirm the signal. If the second pass through the SNM monitor does not result in a detection, then a third pass through the monitor should be conducted to verify no detection. If the second pass through the monitor also generates an alarm, the individual should be retained and subjected to a body search, typically with a hand

-held monitor, as described in ASTM C1237

-99 (2005), (Ref. 11) to locate and identify the source of the signa

l. If the hand

-held monitor does not confirm the alarm signals generated by the doorway monitor, the hand-held monitor should be tested against a known source to confirm it is working properly. If it responds to the source in the anticipated manner, it should be concluded that the doorway monitor should be tested, repaired if necessary, and retested before returning to service. The individual generating the alarm should be released after confirmation that no SNM was detected.

If detection is suspected to be from SNM contamination, health physics personnel should verify this finding. A monitoring flow diagram is provided in Figure 1.

h. A hand-held SNM monitor should be used when the doorway monitor is not functioning as intended. Search personnel should be trained on the correct use of the hand-held monitoring. A hand-held monitor should have the capability to identify specific radioisotopes.

RG 5.27, Rev. 1, Page 9 3. Physical Searches and Training a. A physical search for concealed SNM should be conducted as necessary.

b. To enhance the probability of detection, random search es for concealed SNM at the protected area boundary may be conducted, including search es of hand-carried items.

c. At facilities with formula quantities of strategic SNM, personnel having search duties and responsibilities must be trained and qualified

.(10 C FR 73.45(g)(1)(i)).

Pedestrian in Monitoring Zone Sets Off Alarm at First and Second Pass Hand-Held Detector Search for Source Nuclide?SNM?Tactical Response by Security Release Pedestrian Release Pedestrian Document False Alarm for Later Investigation Yes No Yes No Document Type of Nuclide Detected Figure 1 Flow diagram for SNM searches

RG 5.27, Rev. 1, Page 10 4. Calibration, Testing, Maintenance, and Operating Instructions a. Calibration Doorway and hand

-held monitors should be calibrated with a source of the amount, configuration, and variety of SNM to be detecte

d. Doorway and hand

-held monitor calibration should be conducted in accordance with Reference

7 or as recommended by the manufacturer. Calibration should be conducted before initial use and after monitor repair or maintenance. Calibration should be conducted at least every three months.

As a quality assurance measure, consideration should be given to having SNM calibration standards traceable to certified reference standards or materials. b. Testing (1) Doorway , Hand-Held and Vehicle SNM Monitors Methods of performance testing doorway and hand

-held monitors are found within ASTM C993-97(2012), (Ref. 12) and Reference 9 (as well as reference

1 3). The se references may be used to develop instructions for testing SNM monitors to assure system specifications are met. Daily testing should be a simple functional test (i.e. operational test) to assure the detector is working.

Daily testing should be performe d during each shift, or once per day if there is only one shift. Reference 9 describes an acceptable approach for daily testing.

As described in reference

9 and reference 1

1 , testing sources may be different than those used during calibration.

(2) Metal Detectors Sensitivity mapping and operational sensitivity testing methods are described within ASTM C1270

-97 (2012), (Ref. 13), ASTM C1269-97 (2012), (Ref 14) and ASTM C1309-97 (2012), (Ref 15). The references may be used to develop instructions for performance testing the metal detection system used to search for concealed, shielded strategic SNM. The metal detection system should be capable of detecting the minimum metal shielding concealed anywhere on an individual three times out of three trials. Performance testing should be conducted at least once every three months. The performance testing should include passing the minimum metal test source through a honeycomb configuration test apparatus that covers the entire detection area as described

in references 1 3 , 1 4 and 1 5. The honeycomb channels should be a maximum of 6 inches by 6 inches in dimension. The test source should be passed through the detection area as close as possible to the same rate (speed) as a pedestrian walking through the metal detector unit. Attaching the metal test source to a wooden dowel rod to conduct this test can facilitate the effective rate of passage of the metal source through the honeycomb test apparatus. A detection of the metal test source in each of the honeycomb test channels constitutes an acceptable performance test.

Daily operability testing should be conducted once per shift, or at least daily.

c. Maintenance Metal detection and SNM monitoring equipment shall be maintained to be operable and effectiv e as intended (10 CFR 73.20(4), 10 CFR 73.46(g), and

10 CFR 73.60(d)(1)).

RG 5.27, Rev. 1, Page 11 d. Operating Instructions Operating instructions should be available near the search activity. The procedural elements listed below should be included in the procedures for the search activity. A management system shall provide for the development, revision, implementation, and enforcement of security procedures (10 CFR 73.46 (b)(3)). Written procedures detailing the duties of search personnel for operation of SNM monitors and metal detection equipment shall be developed (10 CFR 73.46 (b)(3)(i)).

Procedures should address the following:

metal detection threshold criteria, test sources and their use, monitor background reduction and sensitivity, searching pedestrians with doorway and hand

-held monitors, recording, retention, and analysis of monitor performance data, recording and resolution of alarm events, quarterly performance testing, daily operational testing, environmental operating constraints (e.g., temperature and humidity), search operations during an emergency or loss of power, maintenance of monitors and metal detection equipment, security for the system equipment, communications, software, and data, training for operating personnel, and documentation requirements for authorized removals of SNM.

D. IMPLEMENTATION

The purpose of this section is to provide information on how applicants and licensees

4 may use this guide and information regarding the NRC's plans for using this RG. In addition, it describes how the NRC staff complies with the Backfit Rule found in

10 CFR 50.109(a)(1), 10 CFR 70.76(a)(1), and 10 CFR 76.76(a)(1) or any applicable finality provisions in

10 CFR Part 52. Use by Applicants and Licensees Applicants and licensees may voluntarily

5 use the guidance in this document to demonstrate compliance with the underlying NRC regulations. Methods or solutions that differ from those described in this RG may be deemed acceptable if they provide sufficient basis and information for the NRC staff to verify that the proposed alternative demonstrates compliance with the appropriate NRC regulations.

Current licensees may continue to use guidance the NRC found acceptable for complying with the identified regulations as long as their current licensing basis remains unchanged. The acceptable guidance may be a previous version of this RG. Licensees may use the information in this RG for actions which do not require NRC review and approval. However, voluntarily using the subject matter in the guidance may change the facilities

4 In this section, "licensees" refers to holders of, and the term "applicants" refers to applicants for, the following: (1) special nuclear material licenses under

10 CFR Part 70; (2) operating licenses under

10 CFR Part 50; (3) combined licenses under

10 CFR Part 52; and (4) certificates of compliance or approvals of a compliance plan for gaseous diffusion plants under

10 CFR Part 76.

5 In this section, "voluntary" and "voluntarily" means that the licensee is seeking the action of its own accord, without the force of a legally binding requirement or an NRC representation of further licensing or enforcement action.

RG 5.27, Rev. 1, Page 12 security plan such that NRC review may be required under the provisions of

10 CFR Part 50.54, 10 CFR Part 70.32 or

10 CFR Part 76.68, and should be evaluated prior to incorporating the methods into the security plans. Licensees may use the information in this RG or applicable parts to resolve regulatory or inspection issues.

Use by NRC Staff The NRC staff does not intend or approve any imposition or backfitting of the guidance in this RG. The NRC staff does not expect any existing licensee to use or commit to using the guidance in this RG, unless the licensee makes a change to its licensing basis. The NRC staff does not expect or plan to request licensees to voluntarily adopt this RG to resolve a generic regulatory issue. The NRC staff does not expect or plan to initiate NRC regulatory action which would require the use of this RG. Examples of such unplanned NRC regulatory actions include issuance of an order requiring the use of the RG, generic communication, or promulgation of a rule requiring the use of this RG without further backfit consideration.

During regulatory discussions on plant specific operational issues, the staff may discuss with licensees various actions consistent with staff positions in this RG, as one acceptable means of meeting the underlying NRC regulatory requirement. Such discussions would not ordinarily be considered backfitting even if prior versions of this RG are part of the licensing basis of the facility. However, unless this RG is part of the licensing basis for a facility, the staff may not represent to the licensee that the licensee's failure to comply with the positions in this RG constitutes a violation.

If an existing licensee voluntarily seeks a license amendment or change and (1) the NRC staff's consideration of the request involves a regulatory issue directly relevant to this revised RG and (2) the specific subject matter of this RG is an essential consideration in the staff's determination of the acceptability of the licensee's request, then the staff may request that the licensee either follow the guidance in this RG or provide an equivalent alternative process that demonstrates compliance with the underlying NRC regulatory requirements. This is not considered backfitting as defined in

10 CFR 50.109(a)(1), 10 CFR 70.76(a)(1), or 10 CFR 76.76(a)(1)

or any applicable finality provisions in

10 CFR Part 52. If a licensee believes that the NRC is either using this RG or requesting or requiring the licensee to implement the methods or processes in this RG in a manner inconsistent with the discussion in this Implementation section, then the licensee may file a backfit appeal with the NRC in accordance with the guidance in NUREG

-1409, "Backfitting Guidelines," (Ref. 18) and the NRC Management Directive 8.4, "Management of Facility

-Specific Backfitting and Information Collection" (Ref 19).

RG 5.27, Rev. 1, Page 13 REFERENCES

6 1. U.S. Code of Federal Regulations , "Domestic Licensing of Production and Utilization Facilities

," Part 50 (10 CFR 50), Title 10, "Energy." 2. 10 CFR 52 , "Licenses, Certifications, and Approvals for Nuclear Power Plants," Title 10, "Energy" 3. 10 CFR 76, "Physical Protection of Plants and Materials," Title 10, "Energy" 4. 10 CFR 73, "Certification of Gaseous Diffusion Plants," Title 10, "Energy" 5. U.S. Nuclear Regulatory Commission (NRC), "Entry/Exit Control of Personnel Access to Protected Areas, Vital Areas, and Material Access Areas," Regulatory Guide (RG) 5.7, Washington, DC, Agencywide Document Access and Management System (ADAMS) Accession No.

ML003739976

. 6. NRC, "Access Control Systems: Technical Information for NRC Licensees," NUREG-1964, Washington, DC. (ML1115A078)

7. Knoll, Glenn F., "Radiation Detection and Measurement," 4th ed., John Wiley and Sons

7 , 20 10. 8. LA-UR-96-4505, "An Optimized International Vehicle Monitor," R. L. York, D. A. Close, and P. E. Fehlau, Los Alamos National Labs, Los Alamos, NM (1997).

8 9. American Society for Testing and Materials (ASTM)

C1189-11, "Standard Guide to Procedures for Calibrating Automatic Pedestrian SNM Monitors," West Conshohocken, PA.

9 10. ASTM , C1112-99(2005), "Standard Guide for Application of Radiation Monitors to the Control and Physical Security of Special Nuclear Material," West Conshohocken, PA.

11. ASTM C1237

-99(2005), "Standard Guide to In

-Plant Performance Evaluation of Hand

-Held SNM Monitors," West Conshohocken, PA.

12. ASTM C993-97(2012), "Standard Guide for In

-Plant Performance Evaluation of Automatic Pedestrian SNM Monitors," West Conshohocken, PA.

6 Publicly available NRC published documents are available electronically through the NRC Library on the NRC's public Web site at http://www.nrc.gov/reading

-rm/doc-collections/

and through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading

-rm/adams.html The documents can also be viewed online or printed for a fee in the NRC's Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD. For problems with ADAMS, contact the PDR staff at 301

-415-4737 or (800) 397

-4209; fax (301) 415

-3548; or e-mail pdr.resource@nrc.gov

.

7 Copies of this publication and, or current edition are available thru the Wiley website at: http://www.wiley.com/

8 Copies of this publication are available thru the US Department of Energy, Office of Scientific and Technical Information (OSTI) website at: http://www.osti.gov/scitech/servlets/purl/444040

9 Copies of American Society for Testing and Materials (ASTM) standards may be purchased from ASTM, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428

-2959; telephone 610

-832-9585. Purchase information is available through the ASTM Web site at http://www.astm.org

.

RG 5.27, Rev. 1, Page 14 13. ASTM C1270

-97(2012), "Standard Practice for Detection Sensitivity Mapping of In

-Plant Walk Through Metal Detectors," West Conshohocken, PA.

14. ASTM C1270

-97(2012), "Standard Practice for Detection Sensitivity Mapping of In

-Plant Walk Through Metal Detectors," West Conshohocken, PA. 15. ASTM C1269

-97(2012), "Standard Practice for Adjusting the Operational Sensitivity Setting of In-Plant Walk

-Through Metal Detectors," West Conshohocken, PA

16. ASTM C1309

-97(2012), "Standard Practice for Performance Evaluation of In

-Plant Walk-Through Metal Detectors," West Conshohocken, PA

17. ASTM C1236

-99(2005), "Standard Guide for In

-Plant Performance Evaluation of Automatic Vehicle SNM Monitors," (Withdrawn 2014) West Conshohocken, PA

18. International Atomic Energy Agency (IAEA), "IAEA Nuclear Security Series No. 13, Nuclear Security Recommendations on Physical Protection of Nuclear Material and Nuclear Facilities," Vienna, Austria, January 2011.

10 19. NRC, "Backfitting Guidelines,"

NUREG-1409 , Washington, DC. (ML032230247)

20. NRC, "Management of Facility

-specific Backfitting and Information Collection

," Management Directive 8.4, Washington, DC.

(ML12059A460)

10 Copies of International Atomic Energy Agency (IAEA) documents may be obtained through their Web site: WWW.IAEA.Org/

or by writing the International Atomic Energy Agency P.O. Box 100 Wagramer Strasse 5, A

-1400 Vienna, Austria. Telephone (+431) 2600

-0, Fax (+431) 2600

-7, or E-Mail at Official.Mail@IAEA.Org

RG 5.27, Rev. 1, Page 15


Retrieved from "https://kanterella.com/w/index.php?title=Regulatory_Guide_5.27&oldid=1864359"