Information Notice 1998-14, Undocumented Changes to Non-Power Reactor Safety System Wiring

Undocumented Changes to Non-Power Reactor Safety System Wiring

ML031050184
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:	04/20/1998
From:	Roe J Office of Nuclear Reactor Regulation
To:
References
IN-98-014, NUDOCS 9804150188
Download: ML031050184 (10)

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555-0001 April 20, 1998 NRC INFORMATION NOTICE 98-14: UNDOCUMENTED CHANGES TO NON-POWER

REACTOR SAFETY SYSTEM WIRING

Addressees

All holders of operating licenses or construction permits for test and research reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to inform

addressees of undocumented modifications that have occurred in the scram system wiring of

two research reactors. In the first case, the modification in conjunction with a switch failure

resulted in the reactor being operated for a short time without any technical specification (TS)

required scrams. In the second case, because of a modification, a switch failure could have

resulted in a TS required scram being disabled. It is expected that recipients will review the

information for applicability to their facilities and consider action, as appropriate, to avoid similar

problems. However, suggestions contained in this information notice are not NRC

requirements; therefore, no specific action or written response is required.

Description of Circumstances

Oregon State Universty

On the morning of February 17, 1998, the TRIGA non-power reactor at Oregon State University

(OSU) had completed a routine 14-minute run at 15 watts of power to perform core excess

reactivity measurements. An attempt was made to manually scram the reactor at the end of the

run using the scram button. When the manual scram button did not work, the operators next

step was to turn off power to the scram circuit using the reactor's three-position key switch.

This switch-1s OFF, OPERATE, and RESET positions with a spring return between the

RESET and OPERATE positions. As the operator touched the switch, the switch moved from a

position between OPERATE and RESET to the OPERATE position. The operator then tried the

manual scram button again and this time it worked.

The licensee determined that a buildup of dirt prevented the three-position switch from returning

to the OPERATE position. When the switch is in the RESET position, the scram bus is

disabled. This switch dates to 1967 when the original console was installed. The switch

operated properly during preoperational testing before startup.

Upon further investigation, the licensee discovered that the wiring of the scram circuit was

different from the wiring shown in the Instrument Maintenance Manual provided by the reactor

vndr. Fgure I shows part of the circuitry as designed. If the key switch is in the OPERATE D

04151-'i ureg 1Ds4ows~g- lt;)X

K>

IN 98-14 April 20, 1998 position, ac power is supplied from terminal block one, terminal number four (TBI -4) through

TBI-9, to TB2-3, the A3 and Al contacts of the three-position switch, and then the console

power switch. This allows transformer four (T4) to power the rod magnets. When the key is

turned to RESET, this circuit is opened and the magnet current is cut off. This prevents rod

withdrawal if the rods are down, or causes the rods to drop if they are up. This design feature

prevents a single failure of the three-position switch from disabling the scram circuits. In the

RESET position, power is supplied to the scram reset relays (K19, K20, and K24), which reset

the scram relays (only one scram relay, K12, is shown). If the key switch sticks in the RESET

position, the scram relay will continued to be energized by the reset relay even if a scram signal

occurs. This is not a problem because the power would already be cut off to the magnets.

Figure 2 shows the wiring as found in the OSU console. The wiring that was between TB1-9 and TB2-3 in the "as designed" circuit was between TBI-9 and TBIO-10 in the OSU console.

As a result, there is power to the magnets when the switch is in the RESET or OPERATE

position.

The licensee concluded that the location of the jumper was probably modified during initial

installation of the reactor console in 1967. This modification was probably done to provide

power to the *B deck 3 on the three-position switch to power REACTOR ON lights.

The licensee took a number of corrective actions. The three-position switch was removed, cleaned, relubricated, and reinstalled in the console. The reactor console wiring was restored

to its as-designed condition. The wiring in the scram circuitry and in other non-scram-related

circuits was checked physically and electronically to demonstrate that the wiring in the console

is as designed. The reactor startup procedure was rewritten to test that the magnet power is

cut off when the three-position switch is placed in the RESET position. The reactor console

was subject to routine startup checks and the semiannual console check procedure. The

reactor vendor was contacted to obtain checkout procedures to confirm that all suggested

surveillances are done before reactor operation.

Texas A&M Universiy

OSU quickly placed information about the failure to scram on the Organization of Test, Researth and Training Reactors (TRTR) list server. As a result, the staff at the Texas A&M

University N&clear Science Center checked the logic diagrams for its TRIGA research reactor

and determined that its reactor could not fail to scram. The Texas A&M console differs from the

one at OSU in that there is no master reset equivalence to the three-position switch. Three of

the scrams have push-button spring-returned switches that clear the locked-in alarm on the

console and allow the scram relay coil to be reenergized if the signal is clear.

The licensee also tested the circuit and determined that each of the three scrams associated

with these switches could be defeated by holding its switch down in the RESET position (this

simulated a switch failure). In this case, the failure of a single switch could prevent an individual

scram signal but would have not disabled all scrams. The licensee then checked the wiring

diagrams for the console and discovered that the wiring of the console matched the wiring

diagrams. The RESET switches were wired in parallel with the normally closed scram contacts.

This wiring maintained power to the magnets through one parallel path if the switch was

IN 9S*14 April 20, 1998 depressed, even if a scram contact opened in the other parallel path. The switches should

have been wired in series. The licensee cannot determine when the console was wired this

way, but notes that the console underwent a major upgrade in 1968. The logic diagram, drawn

in 1976, which differs from the wiring diagram and the as-wired console, appears to have been

based on system knowledge of how it should be configured rather than on the actual

configuration.

To correct this situation, the licensee changed the wiring to put the RESET switch in series with

the protective action contacts, physically verified console wiring for scram circuits, identified

various failure modes, and tested the console for proper operation.

Discussion

The circumstances described above demonstrate the importance of controlling modifications, ensuring that all of the consequences of a modification are carefully considered, and ensuring

that design features in the scram circuitry perform as designed. Careful reviews of

modifications through the safety review process can be an effective method to help to ensure

that unintended deleterious effects from modifications do not occur. The identification of safety

system design features could lead to surveillances or tests that could prevent the occurrence of

similar problems. The staff noted that many licensees contacted the NRC to discuss the results

of testing performed on consoles because of the information placed on the TRTR listed server

by OSU.

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.

Jack Roe, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Alexander Adams, Jr., NRR

301-415-1127

.E-mail: axa@nrc.gov

Attachments:

1. Figure 1, *Reactor Operate Circuit, As-Designed"

2. Figure 2, Reactor Operate Circuit - As Found"

3. List of Recently Issued NRC Information Notices-L vD CEm

DOCUMENT NAME: G:WVERN\OSUSCRAM.INF Tech Editor concurred on 3126/98 To receive a copy of this document, indicate in the box C=Copy wlo attachmentlenclosure E=Copy with attachmentfenclosure N = NIcopy

OFFICE PDND (A)D:PDND C:PECB (A)D:DRPIV\S A

NAME AAdams* MMendonca* JStolz* JRoe*

[DATE 03/30198 03/30/98 04/06/98 04/13/98 5'

OFFICIAL RECORD COPY

P6-3 5 P22-1 0 TB10

Switched AC (H)

T P2 Bi B36P22-l1 f6 2 T910 T T1

4 T4

50 Operate Permissive Jumper 1 3 A .34P3-21 TB2 4TB`

1 P3-202 CBB1l A4 >3 P5-4 AC (N) *OFF

0J5) *OPERATE (

• RESET

Part of Console Key Switch

TBl 0

dAC (N)

External Scram

AC (N)

-. (

Kl12 K19 K20 K24 Kl2 l H tK1 6-7 '

Switched AC (H)

Fiaure

. . I-- -

I.. . Reactor--.

OnprAt0

-V-- - --

Circiuit.

- . . -- . -,

Aq-dpeinnadr

--- --- . U.-

Si9 P6-35 P22-10 TB10 TB10

Si "KSwitched AC (H)

82 AC (N) TB1 POWER OR P6-36 P22-11 TB10 E3 T4 P5-1 A2 .

341 P3(2 T82 P3-0

Cal 8L

P5-4 AC (N) f*OF

• OPERATE

• RESET

Part of Console Key Switch

(

TB1 0

SIAC (N)

Exterral Scram

NO

AC (N)

0-

-- 9X6-7 Figr Reco prt 0. 0cft- A Fud

l_______ Switched AC (H) f5B

Ftc

. I

Attachment 3 IN 98-14 April20, 1998 LIST OF RECENTLY ISSUED

NRC INFORMATION NOTICES

Information Date of

Notice No. Subject Issuance Issued to

98-13 Post-Refueling Outage Reactor 4120/98 All holders of operating licenses

Pressure Vessel Leak Testing for nuclear power reactors except

Before Core Criticality those that have permanently

ceased operations and have

certified that fuel has been

permanently removed from the

reactor vessel

98-12 Licensees' Responsibilities 4/3/98 All U.S. Nuclear Regulatory

Regarding Reporting and Follow-up Commission nuclear pacemaker

Requirements for Nuclear-Powered licensees

Pacemakers

9&-1 1 Cracking of Reactor Vessel 3/25/98 All holders of operating licensing

Internal Baffle Former Bolts for pressurized-water reactors

in Foreign Plants (PWRs) except those who have

ceased operation and have

certified that fuel has been

permanently removed from the

reactor vessel.

95-52, Supp. 1 Fire Endurance Test Results 3/17/98 All holders of operating

for Electrical Raceway Fire licenses for nuclear power

Barrier Systems Constructed reactors except those who

From 3M Company Interam have permanently ceased

-ire Barrier Materials operation and have certified that

fuel has been permanently

removed from the reactor vessel.

98-10 Probable Misadministrations 3/9/98 All Medical Licensees

Occurring During Intravascular

Brachytherapy With The

Novoste Beta-Cath System

98-09 Collapse Of An Isocam II 3/5/98 All Medical Licensees

Dual-Headed Nuclear

Medicine Gamma Camera

OL = Operating License

CP = Construction Permit

• KIN  ?-14 April 20, 1998 depressed, even if a scram contact opened in the other parallel path. The switches should

have been wired in series. The licensee cannot determine when the console was wired this

way, but notes that the console underwent a major upgrade in 1968. The logic diagram, drawn

in 1976, which differs from the wiring diagram and the as-wired console, appears to have been

based on system knowledge of how it should be configured rather than on the actual

configuration.

To correct this situation, the licensee changed the wiring to put the RESET switch in series with

the protective action contacts, physically verified console wiring for scram circuits, identified

various failure modes, and tested the console for proper operation.

Discussion

The circumstances described above demonstrate the importance of controlling modifications, ensuring that all of the consequences of a modification are carefully considered, and ensuring

that design features in the scram circuitry perform as designed. Careful reviews of

modifications through the safety review process can be an effective method to help to ensure

that unintended deleterious effects from modifications do not occur. The identification of safety

system design features could lead to surveillances or tests that could prevent the occurrence of

similar problems. The staff noted that many licensees contacted the NRC to discuss the results

of testing performed on consoles because of the information placed on the TRTR listed server

by OSU.

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.

orig /sfd by D. B. Matthews

FOR

Jack Roe, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Alexander Adams, Jr., NRR

301-415-1127 E-mail: axa~nrc.gov

Attachments:

1. Figure 1, OReactor Operate Circuit, As-Designed'

2. Figure 2, uReactor Operate Circuit - As Found"

3. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:WVERN\OSUSCRAM.INF Tech Editor concurred on 3/26198 To receive a copy of this document indicate In the box C=Copy wlo attachmentenclosure E=Copy with attachmentlenclosure N =No copy

OFFICE PDND (A)D:PDND I C:PECB Il (A)D:DRPM I

l NAME AAdams* MMendonca* JStolz* JRoe*

lDATE _ 03/30/98 03/30/98 04106198 j 04/13/98 OFFICIAL RECORD COPY

-- INbe14 April 20, 1998 depressed, even if a scram contact opened in the other parallel path. The switches should

have been wired in series. The licensee cannot determine when the console was wired this

way, but notes that the console underwent a major upgrade in 1968. The logic diagram, drawn

in 1976, which differs from the wiring diagram and the as-wired console, appears to have been

based on system knowledge of how it should be configured rather than on the actual

configuration.

To correct this situation, the licensee changed the wiring to put the RESET switch in series with

the protective action contacts, physically verified console wiring for scram circuits,.identified

various failure modes, and tested the console for proper operation.

Discussion

The circumstances described above demonstrate the importance of controlling modifications, ensuring that all of the consequences of a modification are carefully considered, and ensuring

that design features in the scram circuitry perform as designed. Careful reviews of

modifications through the safety review process can be an effective method to help to ensure

that unintended deleterious effects from modifications do not occur. The identification of safety

system design features could lead to surveillances or tests that could prevent the occurrence of

similar problems. The staff noted that many licensees contacted the NRC to discuss the results

of testing performed on consoles because of the information placed on the TRTR listed server

byOSU.

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.

Jack Roe, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Alexander Adams, Jr., NRR

301-415-1127 E-mail: axa@nrc.gov

Attachments:

1. Figure 1, uReactor Operate Circuit, As-Designed"

2. Figure 2, "Reactor Operate Circuit - As Found"

3. List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:WVERNOSUSCRAM.INF Tech Editor concurred on 3/26198 I

To receive a copy of this document, indicate inthe box C=Copy wlo attachmentlenclosure E=Copy with attachmentenclosure N = Nlcopy

OFFICE

NAME

PDND

AAdams*

I (A)D:PDND

MMendonca*

l C:PECB

JStoz*

I (A)D:DRP

JRoe*

l DATE 03/30/98 03/30/98 04/06/98 04/13/98 OFFICIAL RECORD COPY

IN' XX .

K ApexL 1998 (this simulated a switch failure). In this case, the failure of a single switch could preve an

individual scram signal but would have not disabled all scrams. The licensee then ecked the

wiring diagrams for the console and discovered that the wiring of the console moed the

wiring diagrams. The RESET switches were wired in parallel with the normall y-losed scram

contacts. This wiring maintained power to the magnets through one paralle ath if the switch

was depressed, even if a scram contact opened in the other parallel pathThe switches should

have been wired in series. The licensee cannot determine when the sole was wired this

way, but notes that the console underwent a major upgrade in 1968. e logic diagram, drawn

in 1976, which differs from the wiring diagram and the as-wired co sole, appears to have been

based on system knowledge of how i should be configured rat r than on the actual

configuration.

To correct this situation, the licensee changed the wiring put the RESET switch in series with

the protective action contacts, physically verified conso wiring for scram circuits, identified

various failure modes, and tested the console for probr operation.

Discussion

The circumstances described above demon ate the importance of controlling modifications, ensuring that all of the consequences of a odification are carefully considered, and ensuring

that design features in the scram circuit perform as designed. Careful reviews of

modifications through the safety revie process can be an effective method to help to ensure

that unintended deleterious effects f m modifications do not occur. The Identification of safety

system design features could lead o surveillances or tests that could prevent the occurrence of

similar problems. The staff note that many licensees contacted the NRC to discuss the results

of testing performed on consols because of the information placed on the TRTR listed server

by OSU.

This information notice r uires no specific action or written response. If you have any

questions about the inf ation in this notice, please contact the technical contact listed below.

Jack Roe, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical c ctac: Alexander Adams, Jr., NRR

301-415-1127 E-mail: axaenrc.gov

Attac ent: List of Recently Issued NRC Information Notices

DT e MENT NAME: G:WVERN\OSUSCRAM.INF

To receive a copy f this document. indicate Inthe box C=Copy w/o attachmeE=Copy with co

OFFICE PDND I _ (A)D:PDND l C:PE'CB (A)D:DR hl1 I

NAME AAdams* MMendonca* iQStolz JRoe Jk

DATE 03/30198 03/30/98 g4 /j3198 OFFICIAL RECORD COPY a-) .

IN'- XX

_ ApiV..x, 1998 switch failure). The licensee then checked the wiring diagrams for the console and discovered

that the wiring of the console matched the wiring diagrams. In this case, the failure of a single

switch could prevent an individual scram signal but would have not disabled all scrams. The

RESET switches were wired in parallel with the normally closed scram contacts. This wiring

maintained power to the magnets through one parallel path if the switch was depressed, even if

a scram contact opened in the other parallel path. The switches should have been wired in

series. The licensee cannot determine when the console was wired this way, but notes that the

console underwent a major upgrade in 1968. The logic diagram, drawn in 1976, which differs

from the wiring diagram and the as-wired console, appears to have been based on system

knowledge of how it should be configured rather than on the actual configuration.

To correct this situation, the licensee changed the wiring to put the RESET switch in series with

the protective action contacts, physically verified console wiring for scram circuits, identified

various failure modes, and tested the console for proper operation.

Discussion

The circumstances described above demonstrate the Importance of controlling modifications, ensuring that all of the consequences of a modification are carefully considered, and ensuring

that design features in the scram circuitry perform as designed. Careful reviews of

modifications through the safety review process can be an effective method to help to ensure

that unintended deleterious effects from modifications do not occur. The identification of safety

system design features could lead to surveillances or tests that could prevent the occurrence of

similar problems.

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.

Jack Roe, Acting Director

Division of Reactor Program Management

Office of Nuclear Reactor Regulation

Technical contact: Alexander Adams, Jr., NRR

301-415-1127 E-mail: axa@nrc.gov

Attachment: List of Recently Issued NRC Information Notices

DOCUMENT NAME: G:WVERN\OSUSCRAM.INF

To receive a copy of this document, indicate in the box C=Copy wlo attachment/endosure E=Copy with attachment/enclosure N = No copy

OFFICE PDND I l (A)D:PDND l l C:PECB (A)D:DRPM Il

NAME AAdams OA l MMendonca L4/) T JStolz JRoe

DATE 1 031/)/98 l 0313)198 103/ /98 703/ /98 OFFICIAL RECORD COPY