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 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 inthe 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).

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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

_ 94-89

<_4 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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DATE 11/15/94 11/29/94 11/30/94 12/09/94 12/09/94 Not In 124l1V9

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~'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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DATE 11/15/94 11/29/94 11/30/94 129/94 1209/94V 94 94

^ -OFFI:'CIAL RECOR COP

IN 94- November , 1994 aware of any Is4kcations of corrosion developing inthe upper source position

switch, whicd is coestructed using materials similar to the original bottom

source do"w#mpositls switches. The upper switch Islocated 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 Inthe air line.

This information notice requires no specifi action or written response. Ifyou

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\

Technical Editor*

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IN 94- November , 1994 Page 5 of 5 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 Inthe 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 regional office.

ipproprate

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:/

INOB r/f SCDB r IHNS r/f

DOCUKENT NARE: 6: IRRAD.KKR

Technical Edito

EKraus

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