Information Notice 1996-35, Failure of Safety Systems on Self-Shielded Irradiators Because of Inadequate Maintenance and Training

Failure of Safety Systems on Self-Shielded Irradiators Because of Inadequate Maintenance and Training

ML031060046
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, 05000442, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	06/11/1996
From:	Cool D A NRC/NMSS/IMNS
To:
References
IN-96-035, NUDOCS 9606060078
Download: ML031060046 (8)

UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 June 11, 1996 NRC INFORMATION

NOTICE 96-35: FAILURE OF SAFETY SYSTEMS ON SELF-SHIELDED

IRRADIATORS

BECAUSE OF INADEQUATE

MAINTENANCE

AND TRAINING

Addressees

All U.S. Nuclear Regulatory

Commission

irradiator

licensees

and vendors.

Purpose

The U.S. Nuclear Regulatory

Commission (NRC) is issuing this information

notice (IN) to alert addressees

to two incidents

where safety interlocks

on self-shielded

irradiators (Category

I) failed to prevent inadvertent

exposure.The causes of these exposures

stemmed from a lack of appropriate

maintenance

and/or worker training.

The incidents

include a broken spring -- possibly causing malfunction

of the safety interlock

-- and a worker who intentionally

bypassed a safety interlock.

It is expected that recipients

will review the information

for applicability

to their facilities

and consider actions, as appropriate, to avoid similar problems.

However, suggestions

contained

in this information

notice are not NRC requirements;

therefore, no specific action nor written response is required.Description

of Circumstances

The first incident occurred when an operator may have been able to open the shielded door of an irradiator

with the sources in the exposed position.After irradiation

of several pocket dosimeters, the operator opened the shielded door of the irradiator

to retrieve the dosimeters, but did not perform a radiation

survey, as required by the facility's

internal procedures, before opening the door. Twice, the operator placed one hand inside the irradiator

to retrieve the dosimeters.

Subsequently, the operator observed that the unit timer continued

to count, indicating

that the sources remained in the exposed position.

The operator checked his personal pocket dosimeter, but did not note an unusual reading. However, the operator did not report the incident until questioned

by the radiation

safety officer, who had noted an unusually

high dosimetry

report of 3.55 millisievert

(355 mrem) deep dose equivalent

for the worker. The dose to the right hand was calculated

to be a maximum of 12.5 millisievert

(1.25 rem).The design of the irradiator

includes two interconnected

interlock

systems, intended to prevent unshielded

exposure of the sources. These include a door interlock

system -- designed to allow opening of the shielded door only after the sources are placed in the fully shielded position -- and a source exposure-.

interlock

system -- designed to secure the sources in the fully shielded tDR FE E NO r/C9 03 ?C 0t, II

k k JI IN 96-35 June 11, 1996 position whenever the shielded door is open or unlocked.

The manufacturer

of the irradiator

indicated

that under normal operations, either system individually

wouldiprevent

inadvertent

access to the unshielded

sources.Following

the incident, the manufacturer

of the irradiator

was requested

to perform an onsite inspection

of the irradiator

and facilities.

During the inspection, the manufacturer

noted: (1) the irradiator

was located in an area that was not climate-controlled;

(2) internal components

of the irradiator

were in a degraded state;(3) maintenance

of the irradiator

had last been performed

approximately

10 years ago; and (4) a return spring, integral to the source exposure safety interlock system, was broken. The manufacturer

indicated

that the lack of environmental

control may have accelerated

the degradation

of the internal components

of the irradiator, and that the lack of periodic maintenance

of the irradiator

may have contributed

to the failure of the return spring.The broken return spring may have caused the source securing mechanism

of the source exposure interlock

system to malfunction, possibly allowing exposure of the sources after the shielded door was unlocked and opened. However, during the post-incident

investigation, neither the manufacturer

nor the licensee were able to identify a failed component

of either interlock

system that could have allowed the shielded door to be opened with the sources in the exposed position.

The manufacturer

indicated

that the design of the source exposure mechanism

-- the operator must manually move the sources from the shielded to the exposed position with a lever -- would have provided the operator with a positive indication

of source position even if the interlock

systems failed.Source position would have been further provided by a series of green and red source position lights on the irradiator.

The operator's

actions indicate either a lack of training on the proper functioning

and use of the irradiator, a lack of understanding

of the training provided, and/or a disregard

for following

the established

operating

and safety procedures.

The operator indicated

that the timer continued

to count when the shielded door was opened. However, the manufacturer

reported that the timer automatically

activates

whenever the source lever is manually moved to one of the two source exposed positions

and the lever is fully engaged in the source slot, and stops counting as soon as the lever is moved from the fully engaged position.

The fact that the timer continued

to count indicates that the operator had not moved the sources from the fully exposed and engaged position.

The licensee reported that the operator had been trained in the operation

of the irradiator

and was listed as an authorized

user, but that the irradiator

was used infrequently

and that this was only the operator's

second use of the irradiator

since being trained.The second incident occurred when a maintenance

worker preparing

to perform maintenance

on an irradiator

bypassed the irradiator

door interlock

system to observe movement of the inner irradiation

chamber. The maintenance

was being

K>IN 96-35 June 11, 1996 performed

to correct previous maintenance

that resulted in the irradiator

not functioning

properly.

The maintenance

worker was unaware that, although the sources remained shielded during movement of the irradiation

chamber from the load to irradiate

position, high levels of radiation

scatter would be present.The maintenance

worker, upon hearing the in-room monitor alarm, immediately

returned the radiation

chamber to the 'load' position (maximum shielding).

Although the maintenance

worker was familiar with the operation

of the irradiator

and had been responsible

for its maintenance

for nearly 15 years, the worker apparently

had not been given formal training on radiation

safety or the operation

and maintenance

of the irradiator.

The maintenance

worker was not aware of the scatter radiation

and assumed that since the sources were not directly exposed, radiation

from the sources would be contained

within the device.During this incident, another worker, hired to perform contract maintenance

on the irradiator, was also in the room near the irradiator.

Neither worker wore dosimetry

nor had any documented

training in radiation

safety. Therefore, their doses could only be calculated

based on their recollection

and were estimated

to both be approximately

4 microsievert

(0.4 mrem) whole body.Discussion

Although neither incident resulted in doses in excess of regulatory

limits, the doses received in both incidents

were unnecessary

and possibly could have been avoided with proper training and routine equipment

maintenance.

A similar incident in 1984, where a door interlock

failed, resulted in the operator being exposed to 222 terabequerel

(6000 curies) of cesium-137.

The first incident clearly demonstrates

the need to perform appropriate

maintenance

on these types of units. Even though these units are designed with interlocks

and safety features intended to prevent inadvertent

exposures, the components

of these systems depend on adequate maintenance

to function properly.

Failure to properly maintain these systems and provide appropriate

training could result in unnecessary

exposures.

Manufacturers

of these types of irradiators

frequently

provide initial and periodic training on the operation

of their units and, in some cases, training on other manufacturers'

units, as well. Initial training is typically

a condition

of the license and, therefore, must be provided to all irradiator

users and maintenance

personnel.

Periodic refresher

training is also beneficial

as a reminder for working safely around the irradiator

and provides for a means to receive or disseminate

additional

or updated information.

In addition, most manufacturers

have a recommended

schedule of maintenance

and/or recommended

preventative/periodic

maintenance

that should be performed.

Users of these types of irradiators

should evaluate their usage to determine the applicability

of the recommended

maintenance

to their situation

and usage.Users who operate their unit more than usual or who use their units under harsh conditions

should consider the need for stepped-up

maintenance

or

'-> IN 96-35 June 11, 1996 shortened

maintenance

intervals.

In addition, each manufacturer's

recommended

maintenance

may vary according

to the specific unit or type of use.Therefore, personis performing

maintenance

on their unit may require specific maintenance

training for their unit.Users who are not aware of the required training for their unit, or who wish to receive information

concerning

training in general, should consult their license, licensing

authority, or the manufacturer

of the unit. Regulatory

Guide 10.9, provides additional

guidance in this area and may assist persons who wish to develop a training and maintenance

program. Users who wish to receive additional

information

concerning

recommended

maintenance

for their unit should contact the manufacturer

of the unit. In addition, third-party

service companies

may also be available

for training and maintenance

services for these types of irradiators.

This information

notice requires no specific action nor written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

regional office.I3W¶flstn 8 by9WWstIA Donald A. Cool, Director Division of Industrial

and Medical Nuclear Safety Office of Nuclear Material Safety and Safeguards

Technical

contacts:

Douglas Broaddus, NMSS (301) 415-5847 Internet:dab~nrc.gov

Anthony Kirkwood, NMSS (301) 415-6140 Internet:ask~nrc.gov

Attachments:

1. List of Recently issued NMSS Information

Notices 2. List of Recently issued NRC Information

Notices DOCUMENT NAME: 96-35.IN To receive a copy of this document, Indicate In the box: C' = Copy without attachment/enclosure

• E' -Copy with attachmentjendosure

N

• No copy* See previous concurrence

OFFICE IIMAB* [ClIMAB* [C Tech Editor* l IMOB* [C IMNS* I C, NAME IDBroaddus*

LCamper lEKraus _KRamsey jDCof'DATE 14/17/96 5/28/96 4/01/96 5/31/96 6/4 96 11 OFFICIAL RECORD COPY

j;IN 96-XX May XX, 1996 Users who are not aware of the required training for their unit, or who wish to receive information

concerning

training in general, should consult their license, licensing

authority, or the manufacturer

of the unit. Regulatory

Guide 10.9, provides additional

guidance in this area and may assist persons who wish to develop a training and maintenance

program. Users who wish to receive additional

information

concerning

recommended

maintenance

for their unit should contact the manufacturer

of the unit. In addition, third-party

service companies

may also be available

for training and maintenance

services for these types of irradiators.

This information

notice requires no specific action nor written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

regional office.Donald A. Cool, Director Division of Industrial

and Medical Nuclear Safety Office of Nuclear Material Safety and Safeguards

Technical

contacts:

Douglas Broaddus, NMSS (301) 415-5847 Anthony Kirkwood, NMSS (301) 415-6140 Attachments:

1. List of Recently issued NMSS Information

Notices 2. List of Recently issued NRC Information

Notices DOCUMENT NAME: A:\IRADIATR.FIN

To receive a copy of this docunent, Indicate hI the box: 'C Copy without attachmentlenclosure

WE- = Copy with attachmentlenclosure

ONE copY* See previous concurrence

a OFFICE IMAB I INAB 15 /HTech Editor I IMOB IMN h NAME DBroaddus*

LCam er' 1EKraus* KRamse Kmfl Co DATE 4/17/96 L/46/96 14/01/96 5-13j /96 /OFFICIAL RECORD COPY

IN 96-XX May XX, 1996 Users who are not aware of the required training for their unit, or who wish to receive information

concerning

training in general, should consult their license, licensing

authority, or the manufacturer

of the unit. Regulatory

Guide 10.9, provides additional

guidance in this area and may assist persons who wish to develop a training and maintenance

program. Users who wish to receive additional

information

concerning

recommended

maintenance

for their unit should contact the manufacturer

of the unit. In addition, third-party

service companies

may also be available

for training and maintenance

services for these types of irradiators.

This information

notice requires no specific action nor written response.

If you have any questions

about the information

in this notice, please contact one of the technical

contacts listed below or the appropriate

regional office.Donald A. Cool, Director Division of Industrial

and Medical Nuclear Safety Office of Nuclear Material Safety and Safeguards

Technical

contacts:

Douglas Broaddus, NMSS 301-415-5847 Anthony Kirkwood, RI 610-337-5050

Attachments:

1. List of Recently issued NMSS Information

Notices 2. List of Recently issued NRC Information

Notices DOCUMENT NAME: A:\IRADIATR.FIN

To receiv a copy of this document, Indicate In the box: C' = Copy without attachmentlenclosure

'E' = Copy with aftachment/enclosure

• 'N -No copy lOFFICE IMAB [ IMAB LJTech Editor LAL IMOB LJIMNS INAME DBroaddus

LCamper EKraus wa KRamsey DCool DMTE 4//f/96 4/ /96 4/W /96 4/ /96 4/ /96 OFFICIAL RECORD COPY

KUJ KU Attachment

1 IN 96-35 June 11, 1996 LIST OF RECENTLY ISSUED NMSS INFORMATION

NOTICES Information

' Date of Notice No. Subject Issuance Issued to 96-33 Erroneous

Data from Defec-tive Thermocouple

Results in a Fire 05/224/96 All material and fuel cycle licensees

that monitor tem-perature with thermocouples

96-28 96-21 96-20 96-18 Suggested

Guidance Relat-ing to Development

and Implementation

of Correc-tive Action Safety Concerns Related to the Design of the Door Interlock

Circuit on Nucletron

High-Dose

Rate and Pulsed Dose Rate Remote Afterloading

Brachy-therapy Devices Demonstration

of Associ-ated Equipment

Compliance

with 10 CFR 34.20 Compliance

With 10 CFR Part 20 for Airborne Thorium Incident Reporting Requirements

for Radiography

Licensees 10 CFR 34.20; Final Effective

Date Handling Uncontained

Yellowcake

Outside of a Facility Processing

Circuit Recent Incidents

Involving Potential

Loss of Control of Licensed Material 05/01/96 04/10/96 04/04/96 03/25/96 01/10/96 12/18/95 12/6/95 10/27/95 All material and fuel cycle licensees All NRC Medical Licensees authorized

to use brachy-therapy sources in high-and pulsed-dose-rate

remote All industrial

radiography

licensees

and radiography

equipment

manufacturers

All material licensees authorized

to possess and use thorium in unsealed form All Radiography

Licensees and Manufacturers

of Radiography

Equipment Industrial

Radiography

Licensees.

All Uranium Recovery Licensees.

All material and fuel cycle licensees.

96-04 95-58 95-55 95-51 K> -iKJ Attachment

2 IN 96-35 June 11, 1996 LIST OF RECENTLY ISSUED NRC INFORMATION

NOTICES Information

Date of Notice No. Subject Issuance Issued to 96-34 96-33 96-32 96-31 96-30 Hydrogen Gas Ignition during Closure Welding of a VSC-24 Multi-Assembly

Sealed Basket Erroneous

Data From Defective

Thermocouple

Results in a Fire Implementation

of 10 CFR 50.55a(g)(6)(ii)(A),"Augmented

Examination

of Reactor Vessel" Cross-Tied

Safety Injec-tion Accumulators

Inaccuracy

of Diagnostic

Equipment

for Motor-Operated Butterfly

Valves Requirements

in 10 CFR Part 21 for Reporting

and Evaluating

Software Errors Suggested

Guidance Relating to Development

and Imple-mentation

of Corrective

Action Potential

Clogging of High Pressure Safety Injection Throttle Valves During Recirculation

Recent Problems with Over-head Cranes Transversing

In-Core Probe Overwithdrawn

at LaSalle County Station, Unit 1 05/31/96 05/24/96 06/05/96 05/22/96 05/21/96 05/20/96 05/01/96 05/01/96 04/30/96 04/30/96 All holders of OLs or CPs for nuclear power reactors All material and fuel cycle licensees

that monitor tem-perature with thermocouples

All holders of OLs or CPs for nuclear power reactors All holders of OLs or CPs for pressurized

water reactors All holders of OLs or CPs for nuclear power reactors All holders of OLs or CPs for nuclear power reactors All material and fuel cycle licensees All holders of OLs or CPs for pressurized

water reactors All holders of OLs or CPs for nuclear power reactors All holders of OLs or CPs for nuclear power reactors 96-29 96-28 96-27 96-26 96-25 OL -Operating

License CP -Construction

Permit