ML20154N437

Insp Rept 50-271/86-08 on 860209-27.Violation Noted:Standby Liquid Control Sys Identified as Inoperable During 840714-851003.Concerns Also Identified W/Sys Continuity Monitoring Circuitry

ML20154N437
Person / Time
Site:	Vermont Yankee
Issue date:	03/03/1986
From:	Lester Tripp NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20154N432	List: ML20154N427 ML20154N437
References
50-271-86-08, 50-271-86-8, NUDOCS 8603170324
Download: ML20154N437 (15)

See also: IR 05000271/1986008

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Report No. 86-05

Docket No. 50-271 License No. DPR-28

Licensee: Vermont Yankee Nuclear Power Corporation

RD 5, Box 169, Ferry Road

Brattleboro, Vermont 05301

Facility: Vermont Yankee Nuclear Power Station

Location: Vernon, Vermont

Dates: February 9-27, 1986

Inspectors: William J. Raymond, Senior Resident Inspector

Glenn W. Meyer, Project Engineer

Approved by: . h. ps4 0 8 8b

LR E. Tripp/,fChief, Reactor Projects Section 3A ' D' ate

Inspection Summary: Inspection on February 9-27, 1986 (Report No. 50-271/86-05)

Areas Inspected: Special, unannounced inspection on day time and backshifts of

the events associated with the discovery during surveillance testing on February

8, 1986, that the Standby Liquid Control System was inoperable. The inspection

involved 61 total hours by the Senior Resident Inspector and a Project Inspector.

Results: One apparent LCO violation was identified for the SLC system being in-

operable from July 14, 1984 to October 3, 1985 when required to be operable. Con-

cerns were also identified with the SLC system continuity monitoring circuitry,

the apparent loss of configuration control in the SLC firing circuit wiring, and

the apparent inability to detect a manufacturing error during preservice tests.

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_T_ABLE OF CONTENTS

PAGE

1. Summary............................................................... 1

2. Purpose............................................................... 1

3. Event, Initial Evaluation, and Notification........................... 'l

4. SLC System Description................................................ 2

5. Primer Wiring Change......................................... ........ 3

6. SLC Continuity Monitoring Change...................................... 4

7. .SLC Surveillance Testing..................................-............ 5

8. Previous Circuit Der,ign Changes....................................... 6

9. Previous Maintenance Activities....................................... 7

10. Licensee Conclusions.................................................. 8

11. Inspection Findings................................................... 9

12. Persons Contacted and Management Meetings............................. 10

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1. Summary

During a February 8,1986 surveillance test, Vermont Yankee found that the

SLC system was inoperable due to the inability to actuate the explosive squib

valves. The prior successful actuation of the squib valves had occurred dur-

ing a July 11, 1984 surveillance test. The licensee found that the replace-

ment squib valve explosive primers, installed following the July test and

presumed to be electrically the same as the primers successfully fired, were

electrically different due to a changed connector pin to bridgewire configura-

tion. The primer wiring change was a manufacturing error unknown to the vendor,

Conax Corp., and had not been detected by the licensee during receipt inspec-

tion or preservice testing. The continuity monitoring circuit for the firing

circuit was incapable of detecting the problem.

Although the inspection found that the principal reason the squib valves

failed to fire was due to the primer manufacturing error, irregularities were

also found in the firing circuit. The inspection found that the firing cir-

cuit (external to the primer) had been modified in 1977 as a result of GE SIL

186. The licensee determined that the as-found firing circuit wiring differed

from the wiring design drawing. Apparently, this difference occurred when

difficulties encountered during installation resulted in a needed field modi-

fication to the firing circuit. This field modification did not go through

the normal required review process and therefore was not reflected in a change

to the as-built drawing of the firing circuit.

Ironically, it was found that if the firing circuit field modification had

not been made, the improperly manufactured primers would have fired the squib

valves and allowed the SLC to function as designed. However, since the field

modification would have been approved in 1977 if properly submitted, the pri-

mary cause of the SLC system failure remains the primer manufacturing error

and the failure of the manufacturer and the licensee to detect this error.

The licenste was reviewing corrective actions including firing circuit design

changes, revised surveillance testing, and additional pre-installation checks

at the end of this inspection.

2. Purpose

The purpose of the special inspection was to review the failure of the Standby

Liquid Control (SLC) system during the February 8, 1986, refueling surveil-

lance test and to identify the factors that caused the SLC system to be in-

operable. The reactor was in a cold shutdown, defueled condition to support

the replacement of the reactor recirculation system piping. The SLC syt, tem

was not required to be operable when the discrepant condition was discovered.

3. Event, Initial Evaluation, and Notification

During the SLC surveillance testing per OP 4114 and 4203 on February 8, 1986,

both primer charges for the 14A squib valve failed to fire at 9:45 A.M. when

SLC System I was actuated. The parallel 148 squib valve was not tested as

part of the System 1 testing, and its firing was deferred pending further

investigation of the A circuit.

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Licensee investigation of the System 1 firing circuit determined that the

primer charges were miswired (when compared to Control Wiring Diagram (CWD)

191301, Sheet 1200) by having both 120 VAC high side leads wired to the A-B

primer bridgewires, and both neutrals wired to the C-D primer bridgewires.

The wiring was found rolled (i.e., interchanged) at a local terminal box (TB)

mounted immediately above the squib valve. Instead of the white-black green-

red sequence (W-Bk-G-R) required by the CWD, entering and leaving the TB, the

sequence into the TB was Bk-G-W-R, and the sequence leaving the TB was W-G-

R-Bk. The firing circuit worked properly when tested at 4:19 P.M. after the

TB was rewired per Maintenance Request (MR).86-0278 to agree with the CWD.

The TB wiring for the System 2 squib valve was inspected and also found mis-

wired as follows: sequence into the TB was R-W-G-Bk, and the sequence out of

the TB was Bk-R-G-W. Although different in appearance, the terminal boxes

were electrically the same (e.g. , black connected to white, white connected

to red, etc.).

Even though the SLC system was not required to be operable for the existing

plant mode, licensee personnel deemed it probable that the SLC system would

not have been functional during the last operating cycle (XI) which ended in

September 20, 1985. The licensee notified the NRC Duty Officer per

50.72(b)(2)(iii) at 4:40 P.M. on February 8, 1986, of the potential loss of

function for the SLC system.

Following the appointment of a lead engineer to systematically investigate

and evaluate the as-found SLC conditions, the licensee attempted to perform

OP 4114 on System 2 at 3:15 P.M. on February 11, 1986. The B pump started and

injected into the reactor vessel during the test (through the already open

A valve), but squib valve 11-148 failed to fire. A second notification was

made to the NRC Duty Officer per 10 CFR 50.72(b)(2)(iii).

Reviews completed during this inspection (discussed further below) identified

no modification, maintenance, or testing activities that would have made the

SLC system inoperable following the July 11, 1984 test. As noted below, the

squib valves most likely became inoperable following the installation of new

primer charges during the 1984 test. The inspector concluded that the SLC

system was inoperable from July 11, 1984 until February 8, 1986. The SLC

system was required by Technical Specification 3.4.A to be operable whenever

the reactor had fuel and the mode switch was not in the shutdown position,

i.e., from July 14, 1984 to October 3, 1985. The failure to meet these con-

ditions is a violation of Technical Specification 3.4.A (VIO 86-05-01).

4. SLC System Description

The SLC system consists of two redundant pumps that take suction from a tank

containing sodium pentaborate solution and inject into the reactor vessel

through two normally sealed, closed squib valves mounted in parallel on the

pump discharge line. To initiate SLC injection, the reactor operator turns

a key locked switch on control room panel (CRP) 9-5 to either the System 1

or System 2 position. Turning the switch to the System 1 position causes the

i A pump to start and the A squib valve to open. Should either component in

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System 1 fail, the B pump and B squib valve would then be activated by turning

to the System 2 position. When the system is in a standby mode, a relay

circuit monitors the electrical continuity of the valve firing circuit and

lights a light bulb on CRP 9-5 for each valve when the circuit has continuity.

The wiring configuration for the System 2 firing and monitoring circuits,

which is typical for System 1, is shown in Figure 1. The mechanical details

of the squib valve and explosive chamber are shown in Figure 2. The squib

valve is opened by shearing the cap on the inlet fitting mounted in the valve

flow path. The cap is sheared off by the trigger assembly that is actuated

by two explosive charges in the primer subassembly. Either primer charge is

sufficient to shear the inlet fitting plug. The primer charges are ignited

by concurrently applying 120 VAC to bridgewires embedded in the charges.

Turning the CRP 9-5 control switch to the System 2 position closes contacts

2, 4, 6, and 8, which starts the B pump, applies voltage to the bridgewires

in the B valve primer change, and shunts around control relay 11-678 of the

continuity monitoring circuit. Once actuated, the primer, the trigger assem-

bly, and the inlet fitting cannot be reused and must be replaced.

The as-found wiring of System 2 is shown in Figure 3.

5. Primer Wiring Change

The ifcensee's investigation of the February 8, 1986 event identified a primer

wiring change as the primary cause of the incident. The vendor supplied two

types of primer assemblies with the same part number and drawing number, but

with different wiring between the connector pins and the firing circuit.

The squib valves ere supplied by the Conax Corp. of Buffalo, New York, and

are described in GE Specification 21A5468 and Conax Instruction DS 1832-2,

Rev C dated June 18, 1970. The trigger assembly part number is 1617-139-01.

Revision E of this Conax drawing dated August, 1970 shows a connector pin to

bridgewire grouping of A&B and C&D. The primer subassembly part number is

1621-186-01. Revision E of this drawing dated August, 1970, also shows pin

wiring with the same bridgewire/ configuration. However, Revision K of drawing

1621-186-01 dated Noveraber 2,1982, showed a pin to bridgewire grouping of

1&4 and 2&3 with a labeling convention in the counterclockwice (CCW) direction.

The initial information from the vendor on Feburary 13, 1986 indicated that

the two connectors are electrically equivalent, and further, that only one

type of connector had been produced since 1980.

The licensee completed bench continuity measurements on February 13, 1986 of

two primer subassemblies taken from the 17 items currently available in stores.

The tested subassemblies are labeled type A and B Tor this narrative. The

type A primer (S/N 254) was manufactured in May, 1982 and was obtained under

purchase order 18163. Two primers from this group were installed in the SLC

system squib valves in 1983 under material issue slip 4V0277. When tested

on February 13, 1986, the primer had a pin to bridgewire grouping of 1&4 and

2&3, measured with a CCW rotation, which agreed with Rev K of drawing 1621-

186-01. The type B primer (S/N 557) was manufactured in October,1983, and

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was obtained under purchase order 21182. Two primers from this group were

installed in the SLC squib valves following the July 11, 1984 testing, under

material issue slip 7V543. When tested on February 13, 1986, the type B

primer had a pin to bridgewire grouping of 1&2 and 3&4 when measured in a CCW

rotation, which disagreed with the vendor drawing.

It is notable that primers of either type would have fired in the VY SLC squib

valves if the external circuits were wired in the neutral-hot-neutral-hot

sequence on the CWDs. However, in the as-found hot-neutral-neutral-hot wiring

sequence, only the type A (manufactured in 5/82) primers will fire. To demon-

strate this latter assertion, the licensee performed an in-situ test of a 5/82

primer in the B valve on February 14,19e6 with the wiring in the configura-

tion as-found on February 8, 1986, and demonstrated that the squib valve fired.

The licensee notified the Conax Corp of the above findings on February 14,

1986. Based on these results and their own review, the vendor indicated an

error had occurred internally that would have affected the production of

primer assemblies (i.e., a reversal in pin labeling from a CCW to a CW rota-

tion during a change in manufacturing facilities in 1983). The Conax Corp.

made an oral report to NRC Region I per 10 CFR Part 21 on February 14, 1986.

The vendor's written report will be reviewed by the NRC at a later date. This

item is open pending further NRC review of the vendor report and the licen-

see's actions to determine whether the licensee properly reviewed and used

information supplied by the vendor, or if the vendor did not properly control

and/or document changes to his product (UNR 86-05-02).

6. SLC Continuity Monitoring Circuit

The continuity monitoring circuit, mentioned above, continuously confirms that

the fuses, resistors, wires and bridgewires in each firing circuit are intact

and lights a panel 9-5 light for each valve to confirm this. It does this

by closing a contact in series with the panel light when control relay 11-678

is energized (picked up). The relay is normally energized when 120 VAC is

supplied to one side of the coil, and a path to ground exists through the

following circuit: ISK resistor R1B, fuse F28, primer bridgewire AB, resistors

R3B1-R4B1-R4B2-R382, primer bridgewire CD, fuse F38, ISK resistor R28, and

neutral (see Figure 1).

The inspector noted that in the as-found condition on February 8, 1986,

neither squib valve was capable of perf orming its intended function, yet all

indications available ta the reactor operator indicated that continuity of

the ignition circuit existed.

The monitoring circu'.t indicated continuity existed, even though it would not

fire because the following closed circuit existed (shown for "B" side - typi-

cal for both; see Figure 1): 120 VAC was provided through fuse F1B to one side

of the coil for relay 11-67B; a path to ground existed through resistor R18,

F2A, terminal point FF 54, primer coil BA, terminal point FF 55, fuse F38,

resistor R2B, terminal point FF 53, and to neutral. Only one primer bridge-

wire was included in the monitoring circuit, instead of two for each squib

valve, as is normally the case.

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This item is significant because the configuration at Vermont Yankee is be-

lieved to be typical of the standard circuit design recommended by the vendor.

This item will be reviewed further by the NRC to determine for generic applic-

ability and appropriate followup actions (IFI 86-05-03).

7. SLC Surveillance Testina

Refueling surveillance testing of the SLC system is performed under OP 4114,

SLC System Surveillance, and OP 4203. Maintenance and Testing of SLC Squib

Valves. SLC pump capacity testing is also conducted per OP 4114 on a monthly

basis. For the refueling surveillances, OP 4114 governs the overall sequence

for the conduct of the test and establishes the required plant and system

valve lineup conditions. OP 4203 is performed in conjunction with OP 4114

and provides for bench and simulated in-system electrical testing of the ex-

plosive charges.

The major objective of the tests is to meet the refueling surveillance re-

quirements of the technical specifications, including manual initiation of

the system except the explosion valves, injection of demineralized water into

the reactor vessel, and explosion of one of three charges in a batch to verify

proper function. Accordingly, the tests verify an operable flow path to the

reactor vessel by manually actuating the system using the normal controls from

the control room. Additionally, the tests verify that the explosive charges

installed in the system and to be removed following the test were capable of

being fired using the actual system wiring configuration. Finally, the tests

demonstrate that the batch of charges from which the two replacement primers

will be taken is acceptable by exploding one charge from the batch on a bench

test set-up.

The combined OP 4114 and OP 4203 testing sequence is generally as follows:

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remove the inlet fitting from the A valve and reassemble the valve

body to establish an open flow path to the vessel.

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install the existing primer in a test block mounted adjacent to the

squib.

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fire the A valve primer in place with the system wiring when System

1 is actuated.

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install the existing B primer in a test block mounted adjacent to

the squib.

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fire the B valve when System 2 is actuated.

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install new primers in the A and B squibs valves.

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bench test a new primer with the inlet fitting removed from the A

valve to verify the explosive primer batch is acceptable, and the

charge is capable of shearing the cap.

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install a new inlet fitting in the A squib.

The bench test of the new primer is completed using a type C or D battery

connected across two of the primer electrical pins. It should be noted that

no rewiring of electrical circuits is required to complete the OP 4203 steps.

The firing circuit is disconnected from the in-situ primers by disconnecting

the connector at the primer.

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The last time prior to the 1995-86 outage that the SLC system was tested using

i the above procedures was on July 11, 1984. Both squib valves fired as re-

quired during that test.

8. Previous Circuit Design Changes

The last documented design change on the SLC firing circuitry was PDCR 77-2

on September 17, 1977, to enhance the circuit reliability by adding a second

neutral line (a common neutral existed previously) and to improve the monitor-

ing capability so that the circuit resistors were included in the monitoring

circuit. The changes were made based on General Electric (GE) Services In-

formation Letter (SIL) No. 186, dated July 30, 1976. The inspector reviewed

the nature and scope of the design changes and determined the changes were

appropriate to accomplish the intended objectives.

Further, the changes recorded in the PDCR documentation package would have

prevented the February 8, 1986 event, as it would have resulted in the hot

leads alternating on the primer connector even though the CWD showed an in-

correct connector wire to primer pin configuration. However, it is possible

that the unrecorded deviation from the CWD configuration occurred in 1977

during the PDCR and remained in place as noted in 1983, on January 6, 1986,

and following the 1986 test. During implementation of PDCR 77-2, a circuit

problem was noted that apparently prevented the successful firing of the B

squib valve the first time it was attempted on September 11, 1977. The cir-

cuit problem was corrected by rolling (i.e. interchanging) two wires some

place in the circuit. The evidence for this is a hand written note on the

PDCR Installation and Test Procedure (reference Page 7, Step 45). Based on

an interview with the electrical worker who completed the PDCR wiring, there

are no further details as to what the problem was, what wires were moved, or

whether the circuit wiring drawings were updated. The worker involved with

the job in 1977 did not recall having to roll the wires in the local tbs to

the as-found configuration. The worker further felt that such a change would

have been documented had it been necessary at the time. He supposed that the

wires rolled would have more likely been some of the non-color coded 9-5 panel

wires.

It should also be noted that the licensee identified another deviation between

the as-built conditions and the wiring configuration called for in CWD 191301,

Sheet 1201. The four conductors of cable C11201 were found to terminate at

points DD-89, 90, 94, and 95 in CRP 9-5. The circuit is then carried through

to the intended termination points of FF 54, 55, 56, and 57 using gray bench-

board (SIS) wire. It was these SIS wires the electrician supposed may have

been rolled during PDCR 77-2. Continuity checks completed by the licensee

on February 11, 1986 confirmed that this wiring configuration did not contri-

bute to the test failure on February 8, 1986. The as-built wiring is recorded

on CRP 9-5 panel drawings 5920-3738, Rev. 22 and 5920-3703, Rev. 27. However,

the wiring configuration was recorded on those drawings during an as-built

update of the prints in 1984. There apparently was no attempt made in 1984

to compare the updated panel diagrams with the CWDs. The deviaticn between

the as-found wiring, the CWDs and the panel diagrams most likely existed prior

to 1984,

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The discrepancy between the as-found circuit wiring and the approved de.iign

drawings represents a potential loss of configuration control that is of sig-

nificant concern to the NRC. This matter warrants further review by the lic-

ensee and the NRC to determine whether the wiring configuration noted on

February 8, 1986 resulted from an approved design change. This item is un-

resolved and will be reviewed further on a subsequent NRC inspection (UNR

86-05-04).

9. Previous Maintenance Activities

Maintenance requests (MRs) for the SLC system were reviewed by the licensee

and the inspector to determine which involved the electrical circuits and to

possibly identify a repair activity that may have altered the wiring at the

local terminal boxes. The inspector's review included the following MRs:

83-1303, 83-0450, 83-0500, 83-1064, 83-1180, 83-1136, 84-1185, and 85-2635.

The following items warranted further followup.

Work completed under MRs 83-0450 and 0500 in March-April,1983 resulted in

the change-out of the pigtails (connectors and short length of cable) from

the local terminal boxes to the squib valves. Based en interviews with the

I&C technician who performed the work, the replacement was one-for one, wire-

for-wire. The technician noted at the time that the wiring sequence did not

match the CWD. No further actions were taken since it was noted that the

existing wiring sequence worked based on previous satisfactory performance

of system testing, and the only repair activity was a one-for-one replacement.

The observations by the technician while performing the work under MRs 83-

450/500 indicate that the wiring configuration observed to fail on February

8,1986 was in place prior to the satisfactory test performed per OP 4114 in

July, 1984.

Maintenance was performed per MR 84-1185 on the A squib valve continuity

circuitry on July 13, 1984, two days after performance of the OP 4114 testing.

The problem, loss of squib valve A continuity, was corrected by replacing fuse

F2A. The operability testing completed following the repair consisted of

verification that normal indication and continuity meter readings returned.

While it appears that more rigouous testing following MR 83-1185 may have de-

tected a change in the monitoring circuits, the scope of the actual testing

completed, in the inspector's opinion, was not inappropriate for the nature

of the work completed.

MR 85-2634 was submitted by a reactor operator on December 29, 1985, to in-

vestigate the intermittent occurrence of the squib valve loss of continuity

alarm. The alarm apparently occurred, even though the circuit trickle current

of 0.25 mamp was above the alarm setpoint of 0.1 mamp. The problem appeared

to occur concurrent with a lower voltage condition on the 345 KV grid. How-

ever, no direct association between the two events has been establishe.d.

Troubleshooting activities under MR 85-2634, consisted of visual inspections

and continuity measurements and were completed on January 6, 1986, eten though

the problem had cleared and no further symptoms were present. During this

effort, the I&C technician (who also happened to complete the work under MRs

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83-0450/0500) again noted that the local terminal box wiring did not match

that required by the CWD. The technician further noted that the continuity

readings across the primer bridgewires indicated that the squib valves could

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not possibly fire as wired. No wires were moved. After consulting mainten-

ance personnel to confirm the satisfactory system testing on July 11, 1984,

I&C supervision decided to take no further actions to investigate the anomaly

until after the 1986 SLC testing per (OP 4114), as the system was not required

to be operable, either then or prfor to the test.

Based on the above, the inspector concluded that SLC system maintenance acti-

vities within the scope of the above review did not appear to have contributed

to the wiring configuration noted on February 8, 1986. It also appears that

a minor intermittent problem in the monitoring circuit remains to be investi-

gated and resolved. The licensee should review the monitoring circuit to

assure curent loops are appropriately balanced. This item is open pending

completion of a review by the licensee of the monitoring circuit design and

function and subsequent review by the NRC (IFI 86-05-05).

10. Licensee's Conclusions

The licensee issued Plant Information Report (PIR) 86-03 on February 24, 1986

covering the SLC failure. Under the PIR system, the PIR will be reviewed by

plant management, concurred on by the PORC, and approved by the Plant Manager.

Accordingly, the PIR reviewed by the inspector represented the licensee's

preliminary conclusions and recommendations.

The licensee concluded that the SLC system was inoperable from July 11, 1984

until February 8,1986, and that the primary cause of the event was the in-

advertent, undetected manufacturing error by the vendor, Conax, which changed

the wiring between primer pins and explosive charge bridgewires. The licensee

concluded that the as-found wiring of the firing circuit was a contributing

factor to the event in that its configuration permitted a primer failure with

the inadvertently revised primers. However, the licensee concluded that the

as-found wiring was an acceptable design when utilized with the as-designed

primer and had properly fired the primers many times when correct primers had

been installed. The as-found wiring met the design specified in SIL 186.

The licensee concluded that the difference between the as-found wiring and

the CWD occurred during the installation of the 1977 wiring design change,

and the CWD was never revised to reflect the as-built wiring. The licensee

concluded that such a design change / drawing revision process would have been

unlikely to realize the potential problem and unlikely to result in a differ-

ent wiring.

The licensee concluded that the as-found wiring had existed since the 1977

wiring design change based on the lack of any records of design change or

maintenance activities which would have changed the wiring subsequent to 1977.

Further, PDCR 77-2 and the resultant CWD were not correct, in that the pigtail

cable between the primer connector and the local terminal box was misrepre-

sented (e.g., the black lead connected to pin A, whereas the white lead ac-

tually connects to pin A). The licensee hypothesized that the electricians

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realized this misrepresentation during the installation and revised the wiring

in the terminal box to provide a workable wiring. This field change was then

never implemented on the drawing or approved in the drawing change process.

The PIR contained recomended corrective actions, as follows:

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Revise testing procedure OP 4203 to include pin to pin continuity tests

and a test of new primers using the firing circuit.

--

Revise terminal box wiring such that hot leads alternate around the con-

nector and either primer type will fire.

--

Revise CWD to as-built configuration.

--

Revise procurement program to specify latest drawings are sent with parts.

--

Review other surveillance procedures which test performance of components

following use to determine whether additional testing and design changes

are appropriate.

--

Retest SLC system following completion of other recomendations.

The PIR recomended that no additional changes be made to the design change

and configuration control program, as revisions to these programs since 1977

have instituted administrative controls to ensure that field changes are pro-

perly reviewed and approved and that as-built drawings are completed.

NRC review of the approved PIR 86-03, including the recomended corrective

actions including changes to OP 4203, is an open item (86-05-06).

11. Inst.ection Findings and Conclusions

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A. As documented throughout the report, the inspector identified the fol-

lowing:

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86-05-01; Violation for inoperable SLC system.

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86-05-02; Unresolved item for evaluation of the Conax manufacturing

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error and the licensea's failure to find it prior to use.

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86-05-03; Open item for design of continuity monitoring circuit.

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86-05-04; Unresolved item for loss of configuration control.

--

86-05-05; Open item for repetitive maintenance of continuity moni-

toring circuit.

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86-05-06; Open item for review of PIR recomended changes.

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B. The inspector agreed with the conclusion of the PIR that the primary

cause of the inoperable SLC system was the manufacturing error in the

primer charges.

Concerning the as-found firing cit c91t wirk.g, which permitted the re-

vised primers to fail, the inspector agreed the that this probably re-

sulted during the installation of the 1977 design change and that the

as-found wiring represented an acceptable design implementation of SIL

186.

C. The inspector noted that the Traversing In-core Probe (TIP) shear valves

also incorporate an explosive primer which actuates the valve. The in-

spector's preliminary evaluation of the firing circuit and the primer

component found that the firing circuit was similar to SLC and the primer

also used a four pin connector. Accordingly, the licensee's evaluation

of the applicability of the SLC corrective actions to the TIP shear

valves is an open item (86-05-07).

D. The inspector noted that the licensee had 17 primers in stock following

the incident. As the design life of the primer is five years and only

three primers are used per operating cycle (if the batches are good),

the 17 primers in stock appeared to be excessive. The licensee's shelf

life program, which should prevent usage of outdated primers, is under

development. Also, there appeared to be no provision in the primer in-

sta11ation procedure to ensure the primer's useful life would not expire

during its use. Therefore, the licensee's action to ensure that primers

are installed which will be within their useful life during their use

is an open item (86-05-08).

E. The inspector noted that the February 8, 1986 incident constituted the

first example wherein an apparent vendor supplied product deficiency was

not detected by the licensee's receipt inspection program or post-in-

sta11ation preservice testing, and which rendered a plant safety system

inoperable.

12. Persons Contacted and Management Meetings

Interviews and discussions were conducted with members of the licensee staff

and management during the inspection to obtain inforriation pertinent to the

areas inspected. Preliminary inspection findings were discussed with the

Acting Plant Manager on February 14, 1986, and final inspection findings were

discussed with the Plant Manager on February 27, 1986. The contacted person-

nel included the following people.

Mr. P. Donnelly, Maintenance Superintendent

Mr. J. Halvey, I&C Assistant

Mr. D. McElwee, Senior Engineer - Operations

Mr. M. Stone, Electrician

L. _. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _

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