Information Notice 1994-89, Equipment Failures at Irradiator Facilities

Equipment Failures at Irradiator Facilities

ML031210550
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, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	12/28/1994
From:	Paperiello C J NRC/NMSS/IMNS
To:
References
IN-94-089, NUDOCS 9412210186
Download: ML031210550 (9)

-/UNITED STATES NUCLEAR REGULATORY

COMMISSION

OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS

WASHINGTON, D.C. 20555 December 28, 1994 NRC INFORMATION

NOTICE 94-89: EQUIPMENT

FAILURES AT IRRADIATOR

FACILITIES

Addressees

All U.S. Nuclear Regulatory

Commission

irradiator

licensees.

PurRose The U.S. Nuclear Regulatory

Commission (NRC) is issuing this information

notice to alert addressees

to several equipment

failures -- some of which have generic implications

-- that involve wet source storage irradiators.

It is expected that all recipients (including

dry source storage irradiator

licensees)

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 new NRC requirements;

therefore, no specific action or written response is required.Descrition

of Circumstances

The first equipment

failure involved the time delay system required in 10 CFR 36.23(f).

The second equipment

failure involved two incidents

where the control console provided false indications

of irradiator

condition.

The final equipment

failure involved a source rack that failed to return to its shielded position after the comnand was initiated

at the control console.1. Fault in the Operational

Time Delay Reset Power Supply.In this incident, a fault in the control console circuitry

occurred at a licensee's

facility when an external electrical

power surge caused a fuse to blow in the operational

time delay reset power supply. This circuit had been recently installed

to meet the requirements

of 10 CFR Part 36. The operational

time delay circuit prevents the control console from activating

for a preset time after being initiated

by the operator in the irradiation

room, thereby preventing

source rack movement per 10 CFR 36.23(f).

In addition, the operational

time delay circuit of this irradiator

must be operational

for the audible and visual warning circuit and the door interlock circuit to function properly.

The audible and visual warning systems are designed to activate whenever the irradiator

door is opened and source movement is initiated.

Nevertheless, the audible and visual warning systems did not activate when the operator left the irradiation

room, until the control console was turned 0ON6 with the console key. The planned irradiation

was performed, however, since the audible warning system did activate before irradiation, per the requirement

In 10 CFR 36.31(a).9412210186 PDR ZV > cL(~ (l4eX am t31195 IN 94-89 December 28, 1994 The operational

time delay circuit was also designed to reset after an irradiation

to prevent the control console from being re-energized

and allowing additional

source movement.

The control console should not re-energize until the circuit is again initiated

by the operator In the irradiation

room. However, in this incident, the control console was able to be re-energized

before the time delay circuit was initiated.

The blown fuse in the reset power supply prevented

the time delay circuit from resetting

as designed.To prevent reoccurrence, a surge protector

was installed

to protect the entire system from external power surges, and the time delay circuit was redesigned

to disable the control console, audio and visual safety circuits, and the source positioning

system, in case the fuse blows again. This alerts the operator to a fault and prevents source movement until the fuse is replaced.2. False Indications

of Source Rack Position.A false indication

of source rack position (rack not in the fully down position)

was received at the control console of a wet source storage licensee when the wire that carries the source position signal shorted because of worn insulation.

Vibration

in the system caused the wire to rub against nearby metal and wore away the insulation.

The short-circuit

also caused an initial intermittent

false indication

of a collision

between the source rack and the carrier. The licensee verified that the sources were in the shielded position and traced the fault to the damaged wire. The wire was replaced and rerouted through a flexible conduit to reduce the possibility

of additional

wear.A second false indication

of source rack position occurred at the same facility when the plunger of a source rack down-position

switch failed to extend and thereby did not properly indicate the true position of the source rack. The plunger failed to extend because of corrosion

between the plunger and sleeve causing increased

friction.

The irradiator

licensee received conflicting

signals when the lower position switch indicated

that the source rack was not fully down, but the upper position switch Indicated

that the source rack was fully down. The installed

radiation

monitors and subsequent

surveys performed

outside of the cell indicated

that the source rack was shielded.

Further visual analysis confirmed

that the source racks were in the fully shielded position.The licensee concluded

that the lower source rack position switch was malfunctioning

and replaced the switch. On further analysis of the switch, it was determined

that green corrosion

deposits on the brass sleeve and steel plunger of the switch caused the plunger to stick in the retracted

position, preventing

it from springing

back to the extended position.

With the plunger in the retracted

position, the switch indicates

the source rack is not in the fully down position.

The Irradiator

vendor, Nordion International, Inc.(NII), was notified and has issued Service Bulletin IND-93-2, which is included as Attachment

1 to this information

notice. Service Bulletin IND-93-2 advises all users of NIl pool type irradiators

containing

these plunger-type

position indicators

to check the switches for evidence of corrosion, clean the switches if corrosion

is found, and replace the switches as soon as possible.

IN 94-89 December 28, 1994 In addition, NII has provided replacement

switches constructed

of corrosion- resistant

materials (porcelain

sleeve and stainless

steel plunger) to all users whose irradiators

contain the non-corrosion-resistant

switches, and has provided instructions

for installation

and initial testing of the new switches.3. Failure of Source Rack to Return to the Shielded Position.In this incident, a source rack at a licensee's

facility failed to return to the shielded position.

This occurred when an air solenoid valve failed to fully return to the exhaust position and stuck in an intermediate

position that blocked any air passage through the valve, thereby trapping air pressure in the line between the valve and source rack hoist. During a typical irradiation, the licensee noted an irregular

reading on the control console (not related to source rack position)

and pressed the emergency

stop button.The source rack position indication

on the control console indicated

that one of the two irradiator

source racks failed to return to the fully down/shielded

position.

The installed

radiation

monitors, the position of the source rack cable on the roof of the irradiator

builcing, and subsequent

radiation

surveys performed

outside the Irradiation

cell confirmed

that one source rack had remained in the up/unshielded

position.

Further investigation

revealed that pressure remained in the air line to the source rack hoist, keeping the rack in the exposed position, when this pressure should have been released.

The licensee cut the air line to release the pressure, and the source rack returned to the fully down/shielded

position.

The licensee determined

that one or both of the air solenoid valves in the supply line failed to move to the exhaust position when the source down command was initiated, thereby not lowering the source rack. Both valves were replaced and the source hoist system operated normally.The irradiator

vendor, NII, was notified and both solenoid valves were returned to NII for further investigation.

NII determined

that the solenoid valves that were indicated

to be four-way, two-position (exhaust/pressurize), five-port

valves could in certain circumstances, operate as four-way, three-position (exhaust/pressurize/neutral), five-port

valves. A two-position

valve would exhaust pressure in the air line to the source rack hoist upon loss of supply air pressure, regardless

of valve position.

The neutral position of a three-position

valve would maintain pressure In the air line to the source rack hoist regardless

of supply air pressure.

Therefore, a three-position

valve would not allow for a fail-safe

operation.

The circumstance

that allowed the valve to operate as a three-position

valve was attributed

to the deterioration

and hardening

of the seals in the valve spool, causing the valve spool to stick in the neutral position.

Nil's investigation

showed that it is unlikely that the ingress of contaminants

caused the valve spool to stick in the 'neutral position.

However, NII did not rule that out as a contributing

factor. According

to NII, harding of the seals is thought to be caused by oxidation

over time of the seal material.

One of the spools, in use for over 5 years, showed considerable

hardening

of the seal material, whereas the seals of the other spool, in use for only 14 months, had become hardened, but not as hard as the first valve's seals.

...j IN 94-89 December 28, 1994 As a result of this incident, NII issued Service Bulletin IND-94-1, which is included as Attachment

2 to this information

notice. To preclude future failures of this nature, NlI recommends

that Norgren part 54237-56 valve spools no longer be used in Norgren Nugget 200 Series Source Hoist Valves, part K71EAOO KSI AECKGI, and that Norgren part 54237-58 spools be used as replacement

spools in existing and all new valves of this type used in NII pool type irradiators.

The 54237-58 spools allow for the exhaust of air in all positions, thus eliminating

the possibility

of pressure remaining

in the air line to the source rack hoist on removal of supply air pressure.

In addition, NII recommended

in their report to the licensee, that the spools be replaced periodically

to reduce the possibility

of additional

failures because of seal hardening.

NII's investigation

revealed that detectable

hardening

of the seal material has occurred, in at least one case, within 14 months of use.However, the valve in that case continued

to operate without failure.In addition, NII reports that licensees

who have ordered replacement

valves for the original installed

valves (part K71EAOO KSI AECKGI), may have received replacement

valves labeled with Norgren's

off-the-shelfl

part numbers.Therefore, Norgren Nugget 200 Series Source Hoist Valves with part numbers K71EAOO KS6 KQI, K71EAOO KS6 AECKGI, and any other variants of the K71EAOO valves used for these operations

should have their valve spools replaced also.NII asserts that the construction

and operation

of these valves are identical to the K71EAOO KSI AECKGI valves.Discussion:

The failures of the audible and visual warning systems and operational

time delay to initiate properly were caused by a blown fuse in the operational

time delay reset power supply, failing to cause the timer to reset. This allowed the control console to be energized

and source movement to occur before the operational

time delay being re-initiated, contrary to Part 36 requirements.

The redesigned

circuit prevents this situation

from occurring

by not allowing the control console to re-energize

if this fuse blows again. The control console is designed such that source movement cannot occur unless the control console is energized.

Irradiator

users should evaluate all possible failure modes of source positioning

control circuitry

and interlocks, or circuitry that supports these systems, upon installation

and whenever modifications

are made.The worn insulation

that caused the short in the source rack position indication

circuit did not cause a situation

in which the source racks were in the exposed position unintentionally.

However, the licensee was required to bypass safety interlocks (using appropriate

safety measures)

to verify the true position of the source rack. Users should be aware of and take precautions

against conditions (e.g., wear caused by vibration, excessive heat, embrittlement

caused by high radiation, etc.) which could cause the failure of essential

electrical

components

and indicators.

IN 94-89 December 28, 1994 Users of NII pool-type

irradiators

containing

source down-position

indication

switches constructed

of non-corrosion-resistant

materials

should be aware that if the recommendations

contained

in NII Service Bulletin IND-93-2 are not followed, the potential

for false or conflicting

source rack position signals exists. If a false signal is received, the operator may be required to bypass safety interlocks (using appropriate

safety measures)

to verify the true position of the source rack.The most likely cause of the corrosion

was the close proximity

of the switch to the water line and high humidity in the irradiation

room. To date, NII is not aware of any indications

of corrosion

developing

in the upper source position switch, which is constructed

using materials

similar to the original bottom source down-position

switches.

The upper switch is located away from the water line and is exposed to higher temperatures

and lower humidity when the source rack is in the raised/exposed

position.

However, if conditions

exist in the area around the upper switch that are favorable

to corrosion (e.g., high humidity or a caustic atmosphere), this switch could corrode also.Users of NII pool-type

irradiators

containing

Norgren part 54237-56 valve spools used in Norgren Nugget 200 Series Source Hoist Valves, part K71EAOO, should be aware that if they do not follow the NII recommendation

to replace the 54237-56 spools with 54237-58 spools, the source racks may become stuck in the exposed position.

Licensees

may have to cut the air line to the source rack hoist to return the source rack to the shielded position.

In addition, the licensees

should consider NII's recommendation

that the spools be replaced on a periodic basis to reduce the possibility

of failure, according

to their specific operation.

If not replaced, the replacement

valve spools could fail because of seal material hardening, although such failure would not cause pressure to remain trapped in the air line.This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice, please contact the technical

contact listed below or the appropriate

regional office.Carl J. perie o, Director Division of Industrial

and Medical Nuclear Safety Office of Nuclear Materials

Safety and Safeguards

Technical

contact: Douglas Broaddus, NKSS (301) 415-5847 Attachments:

1. Nordion International

Inc., Service Bulletin IND-93-2 2. Nordion International

Inc., Service Bulletin IND-94-1 3. List of Recently issued NMSS Information

Notices 4. List of Recently issued NRC Information

Notices

<_4 _ 94-89 December 28, 1994 Users of NII pool-type

irradiators

containing

source down-position

indication

switches constructed

of non-corrosion-resistant

materials

should be aware that if the recommendations

contained

in NII Service Bulletin IND-93-2 are not followed, the potential

for false or conflicting

source rack position signals exists. If a false signal is received, the operator may be required to bypass safety interlocks (using appropriate

safety measures)

to verify the true position of the source rack.The most likely cause of the corrosion

was the close proximity

of the switch to the water line and high humidity in the irradiation

room. To date, NII is not aware of any indications

of corrosion

developing

in the upper source position switch, which is constructed

using materials

similar to the original bottom source down-position

switches.

The upper switch is located away from the water line and is exposed to higher temperatures

and lower humidity when the source rack is in the raised/exposed

position.However, if conditions

exist in the area around the upper switch that are favorable

to corrosion (e.g., high humidity or a caustic atmosphere), this switch could corrode also.Users of NII pool-type

irradiators

containing

Norgren part 54237-56 valve spools used in Norgren Nugget 200 Series Source Hoist Valves, part K71EA00, should be aware that if they do not follow the NII recommendation

to replace the 54237-56 spools with 54237-58 spools, the source racks may become stuck in the exposed position.

Licensees

may have to cut the air line to the source rack hoist to return the source rack to the shielded position.

In addition, the licensees

should consider Nil's recommendation

that the spools be replaced on a periodic basis to reduce the possibility

of failure, according to their specific operation.

If not replaced, the replacement

valve spools could fail because of seal material hardening, although such failure would not cause pressure to remain trapped in the air line.This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice, please contact the technical

contact listed below or the appropriate

regional office.Carl J. Paperiello, Director Division of Industrial

and Medical Nuclear Safety Office of Nuclear Materials

Safety and Safeguards

Technical

contact: Douglas Broaddus, NMSS (301) 415-5847 Attachments:

1. Nordion International

Inc., Service Bulletin IND-93-2 2. Nordion International

Inc., Service Bulletin IND-94-1 3. List of Recently issued NMSS Information

Notices 4. List of Recently issued NRC Information

Notices DOCUMENT MANE: 94-89.IN Technical

Editor*EKraus 11/16/94 *See previous concurrence

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j

~'IN 94-~ December , 1994 Users of NII pool-type

irradiators

containing

source down-position

indication

Ailtdas. constructed

of non-corrosion-resistant

materials

should be aware that if the recommendations

contained

In NII Service Bulletin IND-93-2 are not followed, the potmntial

for false or conflicting

source rack position signals exists.- IfMa false signal Is received, the operator may be required to bypass safety interlocks (using appropriate

safety measures)

to verify the true position of the source racuk The most likely cause of the corrosion

was the close proximity

of the switch to the water line and high humidity In the irradiation

room. To date, NII is not aware of any Indicattons

of.corrosion

developing

in the upper source position switch, which Is constructed

using Oateri as similar to the original bottom source down-position

switches.

The upper switch is located away from the water line and Is exposed to higher toWperatures

and lower humidity when the source rack Is in the raised/exposed

position.

However, if conditions

exist in the area around the upper switch that are favorable

to corrosion (e.g., high humidity or a caustic atmosphere), this switch could corrode also.Users of NII pool-type

irradiators

containing

Norgren part 54237-56 valve spools used In Norgren Nugget 200 Series Source Hoist Valves, part K71EA00, should be aware that if they do not follow the NII recommendation

to replace the 54237-56 spools with 54237-58 spools, the source racks may become stuck in the exposed position.

Licensees

may have to cut the air line to the source rack hoist to return the source rack to the shielded position.

In addition, the licensees

should consider NII s recommendation

that the spools be replaced on a periodic basis to reduce the possibility

of failure, according

to their specific operation.

If not replaced, the replacement

valve spools could fail because of seal material hardening, although such failure would not cause pressure to remain trapped In the air line.This information

notice requires no specific action or written response.

If you have any questions

about the information

in this notice please contact the technical

contact listed below or the appropriate

reglonal office.Carl J. Paperiello, Director Division of Industrial

and Medical Nuclear Safety Office of Nuclear Materials

Safety and Safeguards

Contact: Douglas Broaddus, NMSS (301) 415-5847 Attachments:

1. Nordion International

Inc., Service Bulletin IND-93-2 2. Nordion International

Inc., Service Bulletin IND-94-1 3. List of Recently issued NMSS Information

Notices 4. List of Recently issued NRC Information

Notices DOCUMENT NAME: G:IM-IRRAD.KNR

Technical

Editor*EKraus 11/16/94 *See previous concurrence

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RECOR COP

IN 94-November , 1994 aware of any Is4kcations

of corrosion

developing

in the upper source position switch, whicd is coestructed

using materials

similar to the original bottom source do"w#mpositls

switches.

The upper switch Is located away from the water line and Is exposed to higher taperatures

and lower humidity when the source rack is In the ralse/Uxposed

position.

However, if conditions

exist In the area around the upper switch that are vorable to corrosion (e.g., high humidity or a caustic atmosphere), this switc could corrode also.Users of KIU pool-type

irradiato

containing

Norgren part # 54237-56 valve spools used I. Korgren Nugget 200 rios Source Hoist Valves, part # K71EAOO, should be aware that If they do not fllow the NII recommendation

to replace the 54237-S6 spools with 5423748 spo4ls, the source racks may become stuck In the exposed position.

Licensees

may hav to cut the air line to the source rack hoist to return the source rack to shielded position.

In addition, the licensees

should consider NII's recoe ation that the spools be replaced on a periodic basis to reduce the possibility

of failure, according

to their specific operation.

If not replaced, the replace nt valve spools could fail because of seal material hardening, although such fa ure would not cause pressure to remain trapped In the air line.This information

notice requires no specifi action or written response.

If you have any questions

about the information

n this notice, please contact the technical

contact listed below or the appro Wate regional office.Carl J. periello, Director Division f Industrial

and* Medical uclear Safety Office of uclear Materials

Safety and Safegua Contact: Douglas Broaddus, NKSS (301) 415-5847 Attachments:

1. Nordion International

Inc., Service Bulleti IND-93-2 2. Nordion International

Inc., Service Bulletin IND-94-1 3. List of Recently issued NISS Information

Hoti es 4. List of Recently issued NRC Information

Notic s DISTRIBUTION:\

INOB r/f SCOB r/f iNKS r/f DOCIMENT NAME: G:IN-RRAD.KN\

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K>IN 94-November , 1994 aware of any indications

of corrosion

developing

in the upper source pos iton switch, which is constructed

using materials

similar to the original ottom source down-position

switches.

The upper switch is located away from e water line and is exposed to higher temperatures

and lower humidity when e source rack is In the raised/exposed

position.

However, if conditions

exis in the area around the upper switch that are favorable

to corrosion (e.g., h humidity or a caustic atmosphere), this switch could corrode also.Users of NII pool-type

irradiators

containing

Norgren par t 54237-56 valve spools used In Norgren Nugget 200 Series Source Hoist Va es, part t K71EA00, should be aware that if they do not follow the NII rec ation to replace the 54237-56 spools with 54237-58 spools, the source racksay become stuck in the exposed position.

Licensees

may have to cut the ai line to the source rack hoist to return the source rack to the shielded p ition. In addition, the licensees

should consider NII's recommendation

tha the spools be replaced on a periodic basis to reduce the possibility

of failure, in their specific application.

If not replaced, the replacement

alve spools could fail because of seal material hardening, although such fa ure would not cause pressure to remain trapped in the air line.This information

notice requires no sped c action or written response.

If you have any questions

about the informati

in this notice, please contact the technical

contact listed below or the ipproprate

regional office.Carl J. Paperiello, Director Division of Industrial

and Medical Nuclear Safety Office of Nuclear Materials

Safety and Safeguards

Contact: Douglas Broaddu , NMSS (301) 415-5847 Attachments:

1. Nordion Intern lonal Inc., Service Bulletin IND-93-2 2. Nordion Inte ational Inc., Service Bulletin IND-94-1 3. List of Rec tly Issued NHSS Information

Notices 4. List of Re ntly issued NRC Information

Notices DISTRIBMTON:/

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