Information Notice 1994-89, Equipment Failures at Irradiator Facilities: Difference between revisions
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| issue date = 12/28/1994 | | issue date = 12/28/1994 | ||
| title = Equipment Failures at Irradiator Facilities | | title = Equipment Failures at Irradiator Facilities | ||
| author name = Paperiello C | | author name = Paperiello C | ||
| author affiliation = NRC/NMSS/IMNS | | author affiliation = NRC/NMSS/IMNS | ||
| addressee name = | | addressee name = | ||
Line 14: | Line 14: | ||
| page count = 9 | | page count = 9 | ||
}} | }} | ||
{{#Wiki_filter:-/UNITED STATES | {{#Wiki_filter:- / | ||
UNITED STATES | |||
COMMISSION | NUCLEAR REGULATORY COMMISSION | ||
OFFICE OF NUCLEAR MATERIAL SAFETY AND SAFEGUARDS | |||
NOTICE 94-89: EQUIPMENT | WASHINGTON, D.C. 20555 December 28, 1994 NRC INFORMATION NOTICE 94-89: EQUIPMENT FAILURES AT IRRADIATOR FACILITIES | ||
FAILURES AT IRRADIATOR | |||
FACILITIES | |||
==Addressees== | ==Addressees== | ||
All U.S. Nuclear Regulatory | 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 | |||
to | 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 | |||
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 | 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 | |||
source | extend and thereby did not properly indicate the true position of the source | ||
The | 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 | |||
The | source rack was fully down. The installed radiation monitors and subsequent | ||
the | 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 | |||
of | 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. | |||
of | 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 | |||
of | 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 | |||
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 | |||
caused | 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 | |||
in | 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 | |||
to | |||
hardening. NII's investigation revealed that detectable hardening of the seal | |||
of | 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 | |||
to | 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 | |||
to | 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 | |||
should be aware that if the | 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 | |||
in | 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 | |||
cop without at L. 6* WM attachs t L. BE- a Co p1* ous 'on c | |||
OFC IMOB* IMOB* lKE SCDB* INS I | |||
KANE KRamsey/l GPangburn FCombs RBaer MFederline EBrach CPa p 110 | |||
DATE 11/15/94 11/29/94 11/30/94 12/09/94 12/09/94 Not In 124l1V9 | |||
= _ __ _ _ _ FLRoffice 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 | |||
In NII Service Bulletin IND-93-2 are not | if the recommendations contained In NII Service Bulletin IND-93-2 are not | ||
for false or conflicting | 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 measures) | safety interlocks (using appropriate safety measures) to verify the true | ||
to verify the true | |||
position of the source racuk | |||
of the | The most likely cause of the corrosion was the close proximity of the switch | ||
room. To date, NII is | to the water line and high humidity In the irradiation room. To date, NII is | ||
of.corrosion | 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 | |||
without t GP With, tt tu. upt | |||
* U _ ___ | |||
OFC J IMOB* .M SCW lM"+) | |||
KANE KRamsey/ll GPangburn FCombs RBaer NFederline c C'peuello | |||
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* | |||
EKraus | |||
11/16/94 , | |||
mc'. Caov ulthout attedaclMmtc. -V a Caw wifth mttclumVc.qCuu _U_______ - !g | |||
OFC IM | |||
IO I M0BEI l -_ I I S INNS I | |||
INANE IKRUSseYIll | |||
- 6Pnbr | |||
ngur t cobS _ - k . drC~peiel , K\ E~aCh Pe110 | |||
D DAE I 9AT 11/15/94 E | |||
11/29/94 I~ li994 11 1 194 - /q/ I 1 I I | |||
OFFICM RECOD COP | |||
K> | |||
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 | |||
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 | 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 | INOB r/f SCDB r IHNS r/f | ||
DOCUKENT NARE: 6: IRRAD.KKR | |||
===Technical Edito=== | |||
EKraus | |||
* aCWp with~ af m/awd. or a so__________ | / /IC/94 | ||
OR IeBI im CD-1 IA | %'On CpY WitMou sttaduasnwInc. 8E *aCWp with~ af m/awd. or a so__________ | ||
OR IeBI im CD-1 IA * NNS INN | |||
KANEKRams trn VQS RBaer iin Etrach CPaperiello | |||
DATE | DATE L f ff \ F - I J _ j}} | ||
{{Information notice-Nav}} | {{Information notice-Nav}} |
Latest revision as of 03:09, 24 November 2019
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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).
9412210186 PDR ZV > cL(~ (
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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
cop without at L. 6* WM attachs t L. BE- a Co p1* ous 'on c
OFC IMOB* IMOB* lKE SCDB* INS I
KANE KRamsey/l GPangburn FCombs RBaer MFederline EBrach CPa p 110
DATE 11/15/94 11/29/94 11/30/94 12/09/94 12/09/94 Not In 124l1V9
= _ __ _ _ _ FLRoffice 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
without t GP With, tt tu. upt
- U _ ___
OFC J IMOB* .M SCW lM"+)
KANE KRamsey/ll GPangburn FCombs RBaer NFederline c C'peuello
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*
EKraus
11/16/94 ,
mc'. Caov ulthout attedaclMmtc. -V a Caw wifth mttclumVc.qCuu _U_______ - !g
OFC IM
IO I M0BEI l -_ I I S INNS I
INANE IKRUSseYIll
- 6Pnbr
ngur t cobS _ - k . drC~peiel , K\ E~aCh Pe110
D DAE I 9AT 11/15/94 E
11/29/94 I~ li994 11 1 194 - /q/ I 1 I I
OFFICM RECOD COP
K>
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
/ /IC/94
%'On CpY WitMou sttaduasnwInc. 8E *aCWp with~ af m/awd. or a so__________
KANEKRams trn VQS RBaer iin Etrach CPaperiello
DATE L f ff \ F - I J _ j