ML16217A237 

UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

OFFICE OF NUCLEAR MATERIALS SAFETY AND SAFEGUARDS 

WASHINGTON, D.C. 20555-0001 

October 20, 2016 

NRC INFORMATION NOTICE 2016-12: POTENTIAL ABSENCE OF REQUIRED LOCK 

 WASHERS IN BSI INSTRUMENTS, INC. LB 7400 

SERIES FIXED GAUGES 

ADDRESSEES 

All U.S. Nuclear Regulatory Commission (NRC) specific and general fixed gauge licensees and 

service providers. All Agreement State Radiation Control Program Directors and State Liaison 

Officers. 

PURPOSE 

The NRC is issuing this Information Notice (IN) to alert addressees of the potential absence of a 

required lock washer between the source assembly and source holder in BSI Instruments, Inc. 

LB 7400 Series density fixed gauges. The absence of the required lock washer may cause the 

source to become dislodged during use. Recipients should review the information contained in 

this IN for applicability to their facilities and consider taking appropriate action, if necessary. 

However, the information conveyed in this IN is not a new NRC requirement; therefore, no 

specific action or written response is required. 

The NRC is providing this IN to the Agreement States for information and distribution to their 

licensees, as appropriate. 

DESCRIPTION OF CIRCUMSTANCES 

Event 1 

In December 2009, an NRC licensee encountered high radiation levels around a BSI 

Instruments, Inc. (formerly Apgee Corporation) Model LB 7440-D density fixed gauge (LB 7400 

Series), while the licensee was attempting to relocate the gauge. The gauge contained a 5.5 

GBq (150 mCi) cesium-137 source. The radiation field was not reduced when a radiation 

worker moved the shutter to the closed position. The worker retreated from the area within 2 

minutes. Upon removing the source head, a service engineer discovered that the source 

capsule had become unscrewed from the source holder and had fallen into a cylindrical hole 

intended to provide a path for the radiation beam. The service engineer also noticed that a lock 

washer, required between the source and the source holder, was absent. The source was 

removed and placed inside a new source head. 

The root cause of the event was failure of the gauge manufacturer to install a required lock 

washer in the fixed gauge. The licensee identified 35 additional gauges that were missing the 

required lock washer (but had not experienced source capsule detachment or any other 
IN 2016-12 

Page 2 of 3

malfunctions). A public dose assessment for workers in the area determined that six 

nonradiation workers received estimated doses ranging from 1.09 to 1.46 mSv (109 to 146 

mrem), in excess of the 1 mSv (100 mrem) regulatory limit for members of the public. 

Event 2

In February 2016, an Agreement State licensee discovered in its facility a BSI Instruments, Inc. 

fixed gauge Model LB 7442-D (LB 7400 Series), containing 1.1 GBq (30 mCi) of cesium-137, 

with the shutter stuck in the open position. The manufacturer evaluated the gauge, identified 

that the operating rod had been sheared in half, and attributed the malfunction to corrosion 

buildup on the brass shutter shaft. However, during repairs, the service engineer for the 

manufacturer noted that the lock washer between the source holder and the source was 

missing. The manufacturer stated that the missing lock washer could result in the source 

capsule coming loose due to vibration of the source. Other fixed gauges at the facility were 

inspected and were determined to be missing the required lock washer. The lock washers were 

installed in all the affected gauges. 

DISCUSSION 

Although the root causes of the above events are different, they share the similar trait of missing 

lock washers. During use, a Model LB 7400 Series gauge can experience vibration or 

temperature fluctuations that shift its source out of its shielded position within the source 

housing. Also, if this gauge is installed in a vertical orientation, gravity may act upon the source 

capsule and cause the source to fall to the bottom plate of the gauge. Lock washers are 

required because they secure the sources in their installed positions within the source housing. 

This prevents the occurrence of unnecessary personnel exposure, as is illustrated by Event 1. 

The above events suggest that licensees who possess Model LB 7440 Series gauges are likely 

to encounter missing lock washers. For LB 7400 Series fixed gauges, a lock washer should be 

installed between the source assembly and source holder, as described in the gauge’s Sealed 

Source and Device Registry, NR-0112-D-811-B, which has been superseded by 

TN-1031-A-101-B. Therefore, licensees who decide to perform routine maintenance on their 

gauges should exercise caution because of the possibility that some of their gauges may be 

missing the required lock washers. Licensees may wish to consider having a qualified service 

provider verify the installation of the lock washer. Licensees should exercise caution prior to 

performing maintenance on their fixed gauges and should conduct radiation surveys to confirm 

that sources are in their shielded position. 

BSI Instruments, Inc. addressed this issue by requesting and obtaining an amendment to their 

Sealed Source and Device Registration Certificate (NR-0112-D-811-B), requiring that lock 

washers be installed in certain models. The current distributor, Berthold Technologies U.S.A, 

LLC, is aware of this issue in older models distributed by BSI Instruments, Inc. and is actively 

working with customers to refurbish older gauges. The lock washer is incorporated into the 

design of all models distributed by Berthold Technologies U.S.A, LLC, as evidenced in their 

Sealed Source and Device Registration Certificate, TN-1031-D-101-B. 

As a reminder, installation, replacement, removal from service, and disposal of sealed sources 

used in the LB 7400 Series fixed gauges shall only be performed by the device manufacturer, or 

other persons authorized by an Agreement State or U.S. Nuclear Regulatory Commission 

specific license. 
IN 2016-12 

Page 3 of 3

Furthermore, licensees are reminded that Title 10 of the Code of Federal Regulations 

(10 CFR) 30.50(b)(2) requires a report within 24 hours after the discovery of any event in which 

equipment is disabled or fails to function. A 30-day followup report is required by 

10 CFR 30.50(c)(2). 

CONTACT 

This notice requires no specific action or written response. For questions, please contact the 

technical contact below. 

/RA/ 

 Daniel S. Collins, Director 

 Division of Material Safety, State, Tribal 

 and Rulemaking Programs 

 Office of Nuclear Material Safety 

 and Safeguards 

Technical Contact: Celimar Valentin-Rodriguez, NMSS 

 Phone: (301) 415-7124 

 E-mail: Celimar.Valentin-Rodriguez@nrc.gov 

Note: NRC generic communications may be found on the NRC public Web site, 

http://www.nrc.gov, under “NRC Library” > “Document Collections”
IN 2016-12 

Page 3 of 3 

Furthermore, licensees are reminded that Title 10 of the Code of Federal Regulations 

(10 CFR) 30.50(b)(2) requires a report within 24 hours after the discovery of any event in which 

equipment is disabled or fails to function. A 30-day followup report is required by 

10 CFR 30.50(c)(2). 

CONTACT 

This notice requires no specific action or written response. For questions, please contact the 

technical contact below. 

/RA/ 

 Daniel S. Collins, Director 

 Division of Material Safety, State, Tribal 

 and Rulemaking Programs 

 Office of Nuclear Material Safety 

 and Safeguards 

Technical Contact: Celimar Valentin-Rodriguez, NMSS 

 Phone: (301) 415-7124 

 E-mail: Celimar.Valentin-Rodriguez@nrc.gov 

Note: NRC generic communications may be found on the NRC public Web site, 

http://www.nrc.gov, under “NRC Library” > “Document Collections” 

ADAMS Accession No. ML16217A237 *Via e-mail

OFFICE MSTR/MSLB MSTR/MSLB MSTR/MSLB *MSTR/MSEB *QTE MSTR 

NAME CValentinRodriguez 

LSepulveda for 

THerrera 

HGonzalez AMcIntosh CHsu DCollins 

DATE 08/04/16 08/04/16 08/05/16 08/02/16 08/25/16 10/20/16 

OFFICIAL RECORD DOCUMENT