Part 21 Report - 1997-265

ACCESSION #: 9709100168 Victoreen, Inc. September 2, 1997 U.S. Nuclear Regulatory Commission Document Control Center Washington, D.C. 20555 Reference: 10 CFR 21 Report of Noncompliance dated March 26, 1997 Model 530 Electrometer To Whom It May Concern: Further to our notification of the corrective action and close-out dated April 11, 1997, (ref. Exhibit A); this letter has been prepared to provide additional information for your file. Add the attached failure analysis, Exhibit B. Sincerely, Linda S. Nash Director Regulatory Affairs & Quality Assurance 6000 Cochran Road Cleveland, Ohio 44139-3395 (216) 248-9300 FAX (216) 248-9301 DATA (216) 248-9043 'EXHIBIT B' INTEROFFICE MEMORANDUM --------------- Victoreen, Inc. To: Linda Nash From: Bill Zimmermann Date: August 14, 1997 Subject: Model 530 Risk Assessment To assess the risk of a user obtaining an incorrect exposure or rate reading from a Model 530, three components which must be evaluated: 1. The failure rate of the 185-3994-1 resistor network. 2. The percentage of users with more than one ion chamber calibration stored in their 530. 3. The percentage of users who will not notice an abnormal exposure or rate reading. This analysis is limited to those units built prior to April of 1996 containing 185-3994-1 resistor networks (approximately 150 units). Failure rate of the 185-3994-1 resistor network = Total Networks / Total Failed. Total number of 185-3994-1 resistor networks purchased between April 1993 and April 1996 2050 Number of 185-3994-1 resistor network failures between April 1993 and April 19967 Failure rate = 0.34% Percentage of users with more than one calibration factor entered = Users with more than 1 cal factor / Total users. Number of users with more than one cal factor entered = 15 Total number of users = 150 Percentage of users with more than one calibration factor entered = 10% Percentage of users that may not notice abnormal readings = 10% Total risk = 0.0034% or 34 parts per million. Distribution: Charlie Francisco Joe LaPalomento, 'EXHIBIT A' Victoreen, Inc. April 11, 1997 U.S. 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 Close-out, 10 CFR 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 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 R/min (Gy/min). Ion chamber calibration factors can be stored in the model 530 via a computer hook-up, 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 resistor networks have been observed to crack which causes them to open and become non functional. If this occurs, the calibration select switch setting may be read incorrectly by the 5330 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 displaced, 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 Cleveland, Ohio 44139-3395 (216) 248-9300 FAX (216) 248-9301 DATA (216) 248-9043 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 530's with serial numbers between 101 and 128. April 9, 1997 - 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 4CR2596). 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 adapter. 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 front panel by pulling it forward. 4. Locate resistor networks RN1 and RN4 on the Model 530 printed circuit board per drawing below. Figure omitted. 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 L (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. Figure 1 & 2 omitted. 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 Linda S Nash Corporate Director Bill Zimmerman Regulatory Affairs & Q.A Senior R&D Engineer *** END OF DOCUMENT ***

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