Bulletin 97-01: Potential For Erroneous Calibration, Dose Rate, or Radiation Exposure Measurements With Certain Victoreen Model 530 and 530SI Electrometer/dosemeters
OMB No. 3150-0012 NMED No. 970255 NRCB: 97-01 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS WASHINGTON, D.C. 20555 April 30, 1997 NRC BULLETIN 97-01: POTENTIAL FOR ERRONEOUS CALIBRATION, DOSE RATE, OR RADIATION EXPOSURE MEASUREMENTS WITH CERTAIN VICTOREEN MODEL 530 AND 530SI ELECTROMETER/DOSEMETERS Addressees For Action - Nonreactor licensees that possess one of the Victoreen Electrometer/Dosemeters specified in this bulletin For Information - Other medical institution licensees, irradiator licensees, manufacturing and distribution licensees, and calibration service licensees Purpose The U.S. Nuclear Regulatory Commission is issuing this bulletin to: (1) notify addressees about the potential for erroneous calibration, dose rate, and radiation exposure measurements with certain Victoreen Electro- meter/Dosimeters; (2) request that all action addressees take the actions specified below; and (3) require that all action addressees provide NRC with a written response to this bulletin. Description of Circumstances On March 26, 1997, Victoreen notified NRC that some of its Model 530 and 530SI Electrometer/Dosimeter instruments are susceptible to developing cracks in internal resistor networks (see Attachment 1). Victoreen submitted a more detailed written report on April 11, 1997 (see Attachment 2). In this latter report, the affected models and corresponding serial numbers were specified as follows: Model 530 Serial numbers 101 though 250; and Model 530SI Serial numbers 101 through 128. 9704300128. NRCB 97-01 April 30, 1997 Page 2 of 4 Affected models may have, or may develop, a cracked resistor network that could cause erroneous radiation exposure readings either above or below the actual values. Furthermore, if a defective instrument is used as a calibration standard or in determining a calibration standard, any such errors will be propagated in all subsequent measurements made with the erroneously calibrated devices or standards. Various measurements routinely made by NRC licensees could be affected, such as, medical therapy device exposure rates, radiation surveys, and personal dosimetry. Discussion The Victoreen Models 530 and 530SI Electrometer/Dosemeters are high-precision electrometers designed to accept various commercially available ionization chambers. These instruments can be used to either measure electrical charge or current, or, through the use of customer-supplied calibration factors, display these values directly as total exposure (Roentgens or Grays) or exposure rates (Roentgens/minute or Grays/minute). The defective resistor networks comprise part of the calibration factor selection circuitry. If one of these resistor networks cracks, the instrument may actually use a calibration factor other than the one selected by the user, producing erroneous values for exposure and exposure rate measurements. When operated as an electrometer, performing traditional charge or current measurements, the manufacturer indicates that such measurements do not use the problem resistor networks and the charge and current measurements obtained will not be affected by any failures in these resistor networks. Similarly, the manufacturer indicates that if a user does not have any calibration factors stored in the instrument, a cracked resistor network cannot affect the radiation exposure measurement results because there are no calibration factors to select. The potential for a substantial safety hazard exists because measurements made with a defective instrument may result in radiation exposure readings that can be either above or below the actual values by an unknown amount. Furthermore, if an instrument with this fault is used as a calibration standard, all subsequent devices calibrated with reference to the faulty instrument may be in error. If used to calibrate medical therapy exposure rates, patients may be administered radiation over or under the prescribed dose, resulting in potentially significant misadministrations. If used to calibrate survey instruments or personal dosimeters, users may be exposed to radiation levels exceeding allowable limits. Requested Actions Licensees possessing an instrument with a model number and serial number within the range specified above should immediately implement the following actions before any further use of the instrument in performing exposure or exposure rate measurements: 1. Perform the "Customer Corrective Action" recommended by Victoreen to determine if your instrument contains the type of resistor network shown in Figure 2 of Victoreen's report (Attachment 2). . NRCB 97-01 April 30, 1997 Page 3 of 4 2. If the resistor networks are of the type shown in Figure 2 -- a. immediately cease all exposure or exposure rate measurements until the resistor networks are replaced and functionally tested; and b. investigate the operational history of the instrument and identify the activities that may have been affected by erroneous exposure or exposure rate measurements including calibration services provided to other facilities. Required Responses 1. Within 15 days of the date of this bulletin, each action addressee is required to submit a response indicating whether the addressee will implement the actions requested above. If the addressee intends to implement the actions, provide a schedule for completing the actions. If an addressee chooses not to take the requested actions, provide a description of any proposed alternative course of action, the schedule for completing the alternate actions (if applicable), and the safety basis for determining the acceptability of the planned alternative actions. 2. Within 30 days of completing the requested actions, each action addressee is required to submit a report confirming completion of the actions and documenting the results of the investigation specified in Action 2.b. Address the required written responses to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, D.C. 20555, under oath or affirmation, under the provisions of Section 182a, of the Atomic Energy Act of 1954, as amended. In addition, submit a copy to the appropriate NRC Regional Administrator. Licensees should also be aware that electrometers are regulated as medical devices by the U.S. Food and Drug Administration (FDA) if they are used for the calibration of radiation therapy systems that administer patient treatments. Under FDA regulations, Medical Device User Facilities are now subject to mandatory FDA adverse event reporting requirements for medical devices. Information concerning FDA's mandatory reporting requirements can be obtained by contacting the Center for Devices and Radiological Health, Office of Surveillance and Biometrics, Division of Surveillance Systems, at 301-594- 2735. Since the FDA mandatory reporting requirements may not be applicable to all medical device events, FDA also depends on information voluntarily provided by device users because they are often the first to recognize medical device-related hazards. Any concerns that licensees may have regarding safety or quality problems associated with medical devices can be voluntarily reported to the FDA by calling MedWatch at 1-800-FDA-1088. Voluntary reports can be submitted anonymously. Paperwork Reduction Act Statement The information collections contained in this request are covered by Office of Management and Budget clearance number 3150-0012, which expires June 30, 1997. The public reporting burden for collecting this information is estimated to average 40 person-hours per response. This estimate includes the time for reviewing instructions, searching existing data sources, . NRCB 97-01 April 30, 1997 Page 4 of 4 gathering and maintaining the data, and completing and reviewing the collection of information. Send comments about this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to the Information and Records Management Branch, Division of Information Support Services, Office of Information Resources Management, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, and to the Office of Information and Regulatory Affairs, (3150-0012) NEOB-3019, Office of Management and Budget, Washington, DC 20503. Information Addressees NRC is issuing this bulletin to information addressees to alert them to the potential for erroneous radiation exposure measurements with certain Victoreen Electrometer/Dosemeters. It is expected that recipients will review this information for applicability to their facilities and consider actions as appropriate, to avoid similar problems. However, the requested actions and required responses are applicable to action addressees only; therefore, no specific action nor written response is required from information addressees. If you have any questions about this matter, please contact one of the technical contacts listed below or the appropriate NRC regional office. signed by F. C. Combs for Donald A. Cool, Director Division of Industrial and Medical Nuclear Safety Office of Nuclear Material Safety and Safeguards Technical contacts: Robert L. Ayres, NMSS (301) 415-5746 E-mail: firstname.lastname@example.org Kevin M. Ramsey, NMSS (301) 415-7887 E-mail: email@example.com Attachments: 1. Initial Part 21 Report 2. Followup Part 21 Report. Attachment 1 NRCB 97-01 April 30, 1997 Page 1 of 2 Victoreen, Inc. ------------------------------------------------------------------------------ VICTOREEN@ Document Control Desk US Nuclear Regulatory Commission Washington, DC 20555 Subject: Notification of a noncompliance, Model 530 Resistor Network Reference: 10 CFR Section 21.21 Notification to the NRC by fax (301) 816-5151 NRC Operations Center Date of Notification: March 26, 1997 Individual Notifying Commission: Linda S Nash Corporate Director, Regulatory Affairs Bill Zimmerman R&D Engineer Name and address of company notifying the Commission: Victoreen, Inc. 6000 Cochran Road, Cleveland, Ohio 44139-3395 (216) 248-9300 Facility Containing the defect: Victoreen, Inc. 6000 Cochran Road, Solon, Ohio 44139 Date on which the condition was identified: April 15, 1996 Nature of the condition: Resistor network can crack, causing portions of it or all of it to become non-functional. Why we think "this component has caused a substantial safety hazard" This device has not caused a substantial safety hazard 6000 Cochran Road, Cleveland, Ohio 44139-3395 (216) 248-9300 FAX (216) 248-9301 DATA (216) 248-9043 9704010595 970326 PDR PT21 EMVVICTN 97 PDR. Attachment 1 NRCB 97-01 April 30, 1997 Page 2 of 2 Continuation of notification of Model 530 Why we think "this component could cause a substantial safety hazard": Measurements made with a defective instrument may result in radiation exposure readings which are above or below the actual radiation exposure. In the event that the measured readings are below the actual exposure, the actual exposure will be more than the measured exposure. In the event that the readings are above the actual exposure, the actual exposure will be less than the measured exposure. If a faulty instrument is used as a primary calibration standard, all devices calibrated with reference to the faulty device may be in error. If used to calibrate survey meters or personal dosimeters, the users of these devices may be exposed to radiation levels exceeding allowable limits for radiation workers and others. Customers/Utilities Affected: To be determined 2. Attachment 2 NRCB 97-01 April 30, 1997 Page 1 of 4 Victoreen, Inc. ------------------------------------------------------------------------------ VICTOREEN@ April 11, 1997 US Nuclear Regulatory Commission Document Control Center Washington, DC 20555 Reference: 1. 10 CFR 21 Report of Noncompliance dated March 26, 1997 Model 530 Electrometer 2. NRC Fax (301) 816-5151 3. Customer list (see attached) Subject: Corrective Action and Closeout, 10 CFR Part 21 Report of Noncompliance Model 530 Electrometer To Whom It May Concern: Further to our notification dated March 26, 1997, this letter has been prepared to provide formal notification of the corrective action performed and to close out the subject 10 CFR Part 21 Report of Noncompliance General Description: The Victoreen Model 530 Electrometer/Dosemeter is a high precision, dual polarity electrometer designed to accept Victoreen and many commercially available ionization chambers. As an electrometer, it displays charge in nC and current in pA. As a dosemeter it displays exposure in Roentgens (S.I. version - Gy) and Exposure Rate in Rmin (Gy/min). Ion chamber calibration factors can be stored in the model 530 via a computer hookup, but are not required for operation in the charge or current modes. This notification identifies the potential for a component failure in some of the Victoreen Model 530 Electrometer/Dosemeter's (serial numbers 101-250 only) which under very specific circumstances may cause the Model 530 to calculate radiation exposures or rates incorrectly. The component that may fail is a resistor network in the Model 530's calibration select switch circuit. In rare cases these resistors networks have been observed to crack which causes them to open and become nonfunctional. If this occurs, the calibration select switch settings may be read incorrectly by the 530 and one of two things can happen. 1. An -E4- error message is displayed in the Rate and Exposure modes. When this error message is displayed, no measurements may be made. 2. If multiple ion chamber calibration factors have been stored in the 530, an ion chamber calibration factor other than the factor indicated by the calibration select switch may be selected. If this occurs, measurements made in the rate and exposure modes may be in error. In most circumstances, the user would immediately identify the problem. If the unit being calibrated experienced a failure of the same magnitude as the calibration factor error, a substantial safety hazard could occur. The probability of this occurrence is extremely remote. Although the defect was originally discovered in April of 1996, the possibility of a substantial safety hazard was not presented until February 11, 1997. Measurements made in the charge or current modes are not affected. 6000 Cochran Road, 9704240045 970411 Cleveland, Ohio 44139-3395 PDR PT21 EMVVICTN (216) 248-9300 97 PDR FAX (216) 248-9301 DATA (216) 248-9043. Attachment 2 NRCB 97-01 April 30, 1997 Page 2 of 4 April 9, 1997 - Page 2 of 4 If the user has not stored any calibration factors in the 530, a cracked resistor network has no effect because the 530 cannot be used in the rate or exposure mode unless calibration factors have been stored in the 530. This notification applies to Model 530's with serial numbers between 101 and 250, and all Model 530SI's with serial numbers between 101 and 128. . Attachment 2 NRCB 97-01 April 30, 1997 April 9, 1997 - Page 3 of 4 Page 3 of 4 Victoreen Corrective Action: All Victoreen corrective action has been completed. To correct this problem, the original epoxy coated thick film resistor networks (Victoreen 185-3994-1) have been replaced with more durable, molded thick film resistor networks (Victoreen 351041) in all 530's. To implement this change, Victoreen has taken the following action: 1. Replaced all 185-3994-1 resistor networks with 351041 resistor networks in all Model 530's that were returned for repair or calibration since April 16, 1996. (via internal memo) 2. Replaced all 185-3994-1 resistor networks with 351041 resistor networks in all Model 530's and Model 530 main printed circuit boards that were in stock or in process since May 15, 1996. (Ref. DCR 4CR25-96). 3. Changed resistor networks on the Bill of Material for the Model 530-100-10 main printed circuit board from 185-3994-1 to 351041. (Ref. DCR 4CR25-96) since May 15, 1996. Customer Corrective Action: Perform the following visual inspection or call Victoreen Customer Service for assistance. 1. Verify that the Model 530 is turned off and is disconnected from it's AC adaptor. 2. Remove the four Phillips head screws from the front bezel. 3. Lift the front of the top cover to clear the front panel and remove the panel by pulling it forward. 4. Locate resistor networks RN1 and RN4 on the Model 530 printed circuit board per drawing below. (See file BL97001.WP1 for figures). Attachment 2 NRCB 97-01 April 30, 1997 Page 4 of 4 April 9, 1997 - Page 4 of 4 5. Compare the resistor networks to those pictured below. If they are of the type shown in Figure 1, (0.35" tall with square corners) no further action is required. If they are of the type shown in Figure 2, (0.2" tall with rounded corners) reassemble the Model 530 and contact Victoreen Customer Service for assistance. (See file BL97001.WP1 for figures) Root Cause Analysis: From our review it has been determined that the cracking of this resistor network may be the result of manufacturing defects or by mechanical stress, vibration or thermal shock. In our normal processing of these parts they are not subjected to any excess stress, vibration or thermal shock. The functionality of these parts has been tested and is tested on every Model 530 main printed circuit board as part of Victoreen's standard test procedure for this product (Ref. TP530-100-10). We thank you for your cooperation in this matter. Please advise if you have any questions or comments of the information provided here-in. Best Regards (signed Linda S Nash) (signed Bill Zimmerman) Linda S Nash Bill Zimmerman Corporate Director Senior R&D Engineer Regulatory Affairs & Q.A.
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