IR 05000324/1992046

Insp Repts 50-324/92-46 & 50-325/92-46 on 921207-11.No Violations Noted.Major Areas Inspected:Technical Support & Maint Re Electrical Equipment

ML20127D805
Person / Time
Site:	Brunswick
Issue date:	01/05/1993
From:	Fillion P, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20127D797	List: IR 05000324/1992046 ML20127D794
References
50-324-92-46, 50-325-92-46, NUDOCS 9301190047
Download: ML20127D805 (7)

Text

.. .-. - . .

.

g" O'

UNITED ST ATES 8 o g ' NUCLE AR REGULATORY COMMISSION 8 n ntGION 11

$ g j 101 MARIETTA STREET, * '* ATt. ANT A, GEORGI A sd323 5 EG3

%*...*# JAN Report Nos : 50-325/92-46 and 50-324/92-46 Licensee: Carolina Power and Light Company P. O. Box 1551 Raleigh, NC 27602 Docket Nos.: 50-325 and 50-324 License Nos.: DPR-71 and DPR-62 Facility Name: Brunswick 1 and 2 Inspection Conducted: December 7-11, 1992 Inspector: J f E Paul J. Fi ion te gned Approved by: d- $? /2/u/92, M. Shymlock, Chief V tate' Signed Plant Systems Section Engineering Branch Division of Reactor Safety SUMMARY Scope:

This routine, announced inspection was conducted in the areas of technical support and maintenance with regard to electrical equipmen Results:

In the areas inspected, violations or deviations were not identifie Overall, the procedures and controls for maintenance work were adequat One example of apparently not be49 aware of a generic ' industry problem was identifie The System Engineering certification process was moving quite slowly with regard to some. systems. An Inspector Followup Item was established because the clRC intends to followup on a problem with wiring at the large power transformers.

!

9301190047 930105~ 4 PDR ADOCK 0500 G

. . . - . - - .. . . - -. . .

-.

,

REPORT DETAILS Persons Contacted Licensee Employees

{

• K. Ahern, Manager, Unit 2 Operations

• D. Beets, Manager, Electrical System *M. Bradley, Manager, Nuclear Assessment Department -

L. Chambers,- Supervisor,- Relay Maintenance, Transmission Maintenance J. Combs, Manager, Wilmington Area Transmission Naubtebabce

• R. Helme, Manager,- Technical Support

• T. Jones, Senior Specialist, Regulatory Compliance

• M. Kirkland, System Engineer

• W. Leininger, Manager, On-Site Nuclear Engineering Department

• J. Titrington, Manager, Unit 1 Operations ,

L, Troutman, System Engineer H. Wall, Principal Specialist, Unit 1 Operations Other licensee employees contacted during this inspection included engineers, operators, and administrative personne NRC Resident inspectors

• D. Nelson R. Prevatte, Senior Resident

• Attended exit interview Inspection Details This . inspection focused on maintenance activities performed by Transmission Maintenance at the Brunswick Steam Electric Plant:(BSEP)

switchyard, transformer yard and within the power plant. The inspection also evaluated the adequacy of the coordination between Transmission

Maintenance and BSEP personnel.-

The inspection included the _following' specific activities:

2 4 Held discussions with the Manager of Transmission Maintenance

-

(Wilmington,_N.C'.,-area office) and the Supervisor-of the Relay

_

Maintenance Crew concerning their organization, scope of work and ( procedure Reviewed the " Customer / Supplier Agreement," dated September,1991, which outlines the process and responsibilities for coordinating work between Transmission Maintenance and BSEP.

1.

l

,

.. - - - , - - ,

- _ . -. . . - - -. . - .

, ,

,

• Conducted a walkdown inspection of the unit ' auxiliary transformer (UAT) and the startup auxiliary transformer (SAT) for Units 1 and 2 (a total of four transformers).

Reviewed corrective maintenance work request summaries, Adverse Condition Report summary and Licensee Event Reports (the latter for 1990, 1991 and 1992).

Reviewed BSEP's response to two generic industry problems - static electrification af transformers and vulnerability of breaker failure relays to voltage spikes (the latter problem is discussed in NRC :nforiration Notice 91-81).

Since original plant startup there has been some type of customer / supplier agreement between Transmission Maintenance and BSEP.

l One purpose of this agreement was to help ensure that the plant was not l placed in an undesirable configuration with regard to the offsite power i source as a result of maintenance. activities. Procedures implemented under these earlier agreements were not completely effective in that

,

regar In July, 1983, the Transmission Relay Maintenance Crew caused a

! loss of power on a safety-related bus while calibrating a watthourmeter. After this event, they instituted procedures whereby detailed work procedures would have to be followed by Transmission Maintenance and that these procedures would be reviewed by BSEP operations personnel before work could begin. Even these tighter controls were not completely effective in averting problems. On March 5, 1991, an event occurred where the Transmission Relay Maintenance Crew did not return a voltage controlled overcurrent relay (51V) setting to proper configuration following calibration which resulted in a generator trip / reactor scram. About September, 1991, l

Transmission Maintenance began a program of upgrading all work l procedures. And henceforth, the supervisor of the relay crew would L inspect relays after calibration to confirm that the relay had been properly restored. New procedures would call for the supervisor to sign the data sheet to document that the restoration check had been mad A detailed and comprehensive " Customer / Supplier Agreement" went into effect during September, 1991. A key feature of this agreement was that it-called for one BSEP person to be Plant-Transmission Activities Coordinator. In other words, having a single point of contact among BSEP personnel should help avoid coordination type problems. The Manager of Electrical Systems was assigned this coordinator functio On a day-to-day basis, the responsibility was delegated to a System Engineer. Although not specifically stated-in the 1991 agreement document, Transmission Maintenance has agreed to not make any changes to approved work procedures, either substantive, administrative or other, without obtaining approval of BSEP operations personne The inspector concluded that the work procedures governing Transmission-Maintenance activities-at BSEp were adequate for ensuring the integrity of the non-safety-related systems and equipment which comprise the offsite power source. He also noted that there was only_one Licensee l'

il

' . - - . . . .-, ,,, ,7 , , - ~ , ,- -

. . . _ - - . . _ _ , .-

.

Event Report submitted in the last three years which has a bearing on the quality of. work performed by Transmission Maintenance. That was the March, 1991, trip, which was discussed above. However, the inspector did identify a minor problem in failure to document how a deficient condition was resolve ,

The nature of and circumstances surrounding this problem were as-follows. On January 31, 1991, work request No. 91-ACCY1 was written to troubleshoot ground faults on the 1A battery l rtion of the DC Distribution System, in doing this troubleshooting work, BSEP personnel determined that a ground fault existed in the control or indication circuits at the Unit 1 UAT. According to the " Customer / Supplier Agreement," correcting the ground fault at the transformer was turned over to Transmission Maintenanc They determined that the ground fault existed on the wires running between the transformer control cabinet and the oil level switch on the conservator tank. The reason for this ground fault was that the wire insulation had become brittle an cracked. The cracking was observed in a location where multiconductor jacketed cable was run exposed on the transformer tank. The jacket did not appear degraded but the individual conductor -insulation was. The affected wiring to the oil level switch was replaced with suitable -

cable, which had been purchased safety-related, in order to remove.the ground faul At that time BSEP personnel and Transmission Maintenance inspected much of the wicing on the Unit 1 UAT. Based on what was seen in this inspection, the decision was made to inspect wiring on all power transformers and replace wiring as necessary at the next outag When the next outage arrived, some inspections of wiring were performed on all transformers, and some wiring was replaced by Transmission Maintenance. The supervisor's notes indicated that all resistance temperature detector (RTD) wiring mounted outside the VAT-tank wa replaced. His notes indicate that Unit 2 work was performed in the period from September 18, to 20,1991; and Unit I work was performed in the period from August 11-13, 1992. His notes also indicated that the rewiring of the RTD's was independently verifie The inspector made several observations with regard to the inspection and rewiring. First, the RTD wiring in question appeared to be new-wiring. Second, work request No. 92-AUPUI was initiated on August 13, -

1992, to inspect the hot spot current transformer wiring at the Unit 2 UAT. The work request states that a problem was found with the corresponding wiring at Unit 1 UAT. This work request is consistent with the supervisor's notes because the notes stated that Unit 1 UAT

- wiring was being inspected on August 11-13, 1992, the date the work request was initiate Even though the Unit 2 UAT had been inspected-in

'

= September,1991, the work request called for reinspecting the hot spot current transformer circuit in light of the problem seen on Unit Third, the licensee saved a length of the defective RTD wiring, and they

showed it to the inspector. It was seven-conductor cable with a neoprene jacket. The purchase specification for the UAT's called for

. . . .

- -. . . - . . - . -- - . - .-... - ..- . - . . - . ..

-

.

4 .

.,

ethylene propylene rubber insulation with a neoprene jacket for external wiring. Therefore the original wiring appeared to be as specifie Fourth, Transmission Maintenance rewired the RTD's with.their standard substation wiring which is polyethylene insulation with individual conductor polyvinyl chloride (PVC) jacket and overall cable jacket of PV Polyethylene /PVC cable is good to excellent for this applicatio The supervisor's notes did not provide adequate documentation commensurate with the importance and complexity of the problem at han As a result, the status of wiring on the transformers other than the'RTD and hot spot current transformers at the UAT's was somewhat in questio Examples of wiring which should have been inspected [at least on a:

sample basis) but for which inspections were not documented were:

-

Oil level switches

-

Oil temperature indicators

-

Pressure / vacuum gauges

-

Pump and fan motor leads

-

Oil flow indicators During the inspection the System Engineers stated that the transformer defective wiring problem and its resolution should have been documented in a careful auditable manner. To rectify the situation they proposed to perform additional documented inspections before- plant- startup. _In l-addition, Adverse Condition Report (No. B92-971) was written to address-the larger potential problem of the lack of documentation _ described abov The inspector's conclusions with regard to.the transformer wiring =

problem were as follows. In or about February, 1991, the licensee knew .

that certain circuits on the transformer had defective wiring, but the-offsite power supply was considered OPERABLE. The inspector reviewed this decision and agreed that the transformers were operabl.e despite the wiring problem. The transformers could still perform their design-basis function. The contrnl wiring which was exhibitirg the'Ceterioration-was for indication only and its failure would not_ defeat' the function of the:

transformers. The hot spot current transformers and fan and pump motor leads were important to transformer cooling. However, problems with the hot spot current transformers would be-discovered through the daily

~

rounds checking of the hot spot temperature indicators. Cooling motor leads were a lesser concern due -to their relatively cooler location and

, the failure of these cables would not affect the-ability of the l

transformer to carry the required load during and immediately following an accident. Short-circuits on the sudden pressure relay circuit could cause a transformer lockout, but they would manifest themselves during-normal operation. Since the licensee will perform additional inspections of wiring, the NRC desires to followup on this matter.

!

. . - . . . - .- - - . ..

-

.

Therefore, Inspector Followup Item 92-46-01, Transformer Wiring Problems, is establishe The inspector performed a walkdown inspection of the UAT and SAT for both Units. In general, the-inspector _found the transformers were in-good condition. Specifically, the wiring in the control cabinets was not deteriorated, and the workmanship _of the wiring was good. The inspector noted two deficiencies for which the licensee would initiate work request. Those were:

,

-

At Unit 1 SAT, rust on the top inside of the fan controller compartment which could flake off metal fragments and cause a -

short-circuit (WR/JO 92-BHJTl)

At Unit 1 SAT, retaining pin loose on fan manual-thermal-off selector switch which was labeled "EN" (WR/JG was not written during the inspection)

As far as the inspector _could determine there had not been any recent-inspections of the control cabinets, and therefore'the deficiencies noted.did not indicate a problem with the quality of the licensee's inspection With regard to the licensee's response to generic industry problems, the inspector had the following findings and comments. -The licensee had sufficiently investigated and had formulated an adequate response to NRC Information Notice 91-81: Switchyard Problems that Contribute to Loss of Offsite Power. The inspector also inquired as-to whether or not the licensee had addressed the phenomenon of static electrification in power

-

transformer Static electrification is the buildup of static-charge within a transformer as a result of-ionization of the circulating ' oil- as

'

.

it passes through the heat exchangers, pumps, and over the insulating material of the windings. Negative ions. collect on the insulation and~

positive ions in the top oil. The buildup of-charge can-lead to a discharge which can lead.directly to transformer failure. -EPRI' Report EL6081 c_oncludes, based on experimentation, that the problem is aggravated for some conditions where more cooling-capacity is provided than is needed. This can_ result in high oil flow rates' of relatively -

cold oi .

The licensee-presented a copy of. an internal Transmission i Dept, memorandum on the subject of static electrification of l

"

transformers, dated December 9, 1992. The memorandum made the recommendation, which applied to BSEP, that: "the cooling-on our large-base load generator _ stepup transformers not be left running when the units are off line". The licensee's Startup Procedure, OP-50, called for manually starting the initial stage of cooling. However, as far.as the inspector could-determine, the shutdown procedures did not address transformer cooling. Therefore, after an emergency trip the cooling j could be left running for an indefinite period of time, which would be -

l contrary to the recommendations of the memorandu Also, it appeared from reading the memorandum that engineering'had not specifically addressed the backfeeding-mode. During the extended outage

_ _ -

_ -- _

~

1

,. . - .

which was ongoing at the time of the inspection, the plant shutdown loads were receiving power from the grid through the generator stepup -

transformer. The transformer was carrying very -light loads-while all pumps and fans were running. This appeared to be excessive cooling and would be contrary to the intent of the recommendation in the memorandu The licensee agreed that the situation should be reviewed. In conclusion, this evolution with regard to response to industry operating experience, namely the phenomenon of static electrification of transformers, could indicate a minor weakness in this are The-transformer problem has been known for some time, but apparently has not been addressed at BSE During the course of the inspection, the inspector interfaced with engineers from the System Engi_neering group. The-inspector was led t_o the opinion'that System Engineering was not as knowledgeable about the power transformers as one would expect of a system engineer at _a nuclear-power plant. They were basically competent engineers but apparently had not attended specialized training on transformers nor carefully reviewed the operation manua The inspector-learned that one engineer was assigned the following systems in April,1992:

• 24 KV isolated phase bus

'

Caswell Beach pumping station distribution

• 230 KV equipment

• power transformers, ie. GSU, SAT, UAT

-

equipment grounding

• surge protection

-

house power distribution The schedule established by management was- that this engineer would become " certified" on the 230 KV equipment by the end of March, 1993.

'

A schedule had not been established for the other systems. It appears that the certification process was moving _quite slowly with regard to some system . Exit Interview The inspection scope and results were summarized on December 11, 1992-with those persons indicated in paragraph-1. The inspector described the areas inspected and discussed in detail the inspection results including the Inspector Followup Item listed belo Proprietary information is not contained in this report. Dissenting comments were not received from the license IF1 92-46-01, Transformer Wiring Problem .

.\ -

.-

NIC FORM tm PART 2 U.S. NUCLEAR IEGlAATORY COMMIS90N (nen ie a, pc # SAFETY. INSPECTION Page 2 of:, -

_ _ _ . _ _ _ _ . _ _ _ _ _ _ _ _

t _ _ . . m_ . LICENSEE 2. REGIONAL OFFICE p pi REGION I

.(-

s

. , ,

._s; e, . t. . ,' , - e'

y ,

U S NUCLEAR REGULATORY COMMISSION

' ~; t . . L _ k. y , ,

,,g.'

475 ALLENDALE ROAD-r- KING OF PRUSSIA PA 19406 1415

\Q * d

.

\ * # 1

.

k U# 'C d 1 y--.

i trcn T NavnUt:0) 4 llCENSE NUMBER (S) 5 DATE Or INSPECTION b

P I-s =

., r . 3 3 ') A$L -- c, 1 * W-;k '4 . 1 %V

,_

- - - -

2=2c 6 "

.

.

'- ( <w . 1 . 4,

. ( -c .A .i sea

-

r v. ea " k T r~ .4

. - . . - . - -

. .

. 4 4 .3 r(. -4 ,- g v i ts i \,1 . , .

%._

~ !- . . -o r ?

k . ~

, _ _ .

i. t., w i

'

4 -1 A . . ;- d-s.+ u e ( -- A b h' K O s , 1., . \ .

-- * e - , \. . k, \ . d _ . . k-

- hMO & ,- ts

- =- ... - -

- - . . . - - -

. _ - -

. . - . _ _ .

wwm+++-

__

-e

-

'

%d corrective action wn or is being taken and the

__

< .4 \v< , h A ,b'

> ya 'Y' f .. $%

. . .

,

-

_. O

_

a-w. * ~

w I'

/

/