United States Nuclear Regulatory Commission - Protecting People and the Environment


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





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