05000369/LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

ML20071F150
Person / Time
Site:	McGuire
Issue date:	03/02/1983
From:	Tucker H DUKE POWER CO.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20071F154	List: 05000369/LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl 05000369/LER-1983-006-03, /03L-0:on 830131,unit Changed from Mode 5 to 6 W/ Control Room Area Outside Air Pressure Filter Train 2 (VC-B) Inoperable.Subj Train & VC Train a Inoperable on 830125,26 & 29.Caused by Misinterpretation of Tech Specs
References
NUDOCS 8303150451
Download: ML20071F150 (4)

LER-1983-006, Forwards LER 83-006/03L-0.Detailed Event Analysis Encl

Event date:
Report date:
3691983006R00 - NRC Website

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March 2, 1983 Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, Suite 2900 Atlanta, Georgia 30303 he: McGuirs Nuclear Station Unit 1 Docket No. 50-369

Dear Mr.-O'Reilly:

Please find attached Reportable Occurrence Repcrt EO-369/33-06. This report concerns T.S. 3.7.6, "Two independent control area ventilation systems shall be operable", and T.S. 3.0.4, " Entry into an OFERATIONAL MODE or other speci-fied condition shall not be made unless the conditions of the limiting condi-tion for operation are met without reliance on provisions contained in the liCT10N requirements". Titis incident was considered to be of no significance with respect to the health and asfety of the public.

Very truly yours,

1. B. "Ad/

Hal B. Tucker PBN:j fw Attachment cc: Document Control Desk Records Center U. S. Nuclear Regulatory Commission Institute of Nuclear Power Operations Washington, D. C.

20555 1100 circle 75 Parkway, Suite 1500 Atlanta, Georgia 30339 Senior Resident Inspector McGuire Nuclear Station

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DUKE POWER COMPANY McGUIRE NUCLEAR STATION REPORTABLE OCCURRENCE REPORT NO._8_3-06 REPORT DATE: March 2, 1983 FACILITY: McGuire Unit 1, Cornelius, NC IDENTIFICATION: Changed from Mode 5 to 6 with Control Area Ventilation System Train B Inoperable

INTRODUCTION

On January 25, 1983, during Mcdc 5, the Control Rcon Area Outside Air Pressure Filter Train 2 (VC-B) was declared looperc61e. This resulted from the discovery of water-damaged componen:s in the filter packcge.

A faulty loop-seal level control, which isolates filter component drain linee to prevent bypass air flow and drain line backflow, was identified as the

cause

This level control allowed water to back up into the filter package, During Mode 5, no immediate corrective action is required, nor was taket.. upon J

declaring one VC train inoperable. A work request was written to retern VC-B Train to aa operable status. VC-B Train's inoparability io classified ss an Installation Deficiency, since the float operated level control was inproperly installed and adjusted.

VC-A Train was also declared inoperable for several hours on 1/26-27/83, ard again on 1/29/33. This was due to maintenance work on 1FD145 and IPDI44, Fuel Oil Transfer Filter lA2 1 solation valves, which required Diesel Generator IA, and therefore the emergency bus feeding VC-A Train, be declared inoperable.

On 1/31/83, with the VC-B Train still inoperable, the Unit I reactor vessel head was detensioned,'thus entering Mode 6.

Although Technical Specification 3.7.6 Action requirements for Modes 5 and 6 do not address possible mode changes while a VC train is inoperable, Operations personnel evaluated the change to Mode 6 as being no different than continued operation in Mode 5.

Upon review of this action, Duke Power has interpreted this mode change as being a violation of Technical Specification 3.0.4.

This specification states that an operational mode shall not be entered by relying on the action requirements for the opera-bility of an applicable system, unless entering or passing through such a mode as prescribed in the action requirements. This difference in interpretation of the allowability of mode changes is classified as an Administrative Deficiency.

EVALUATION: When preparing to load carbon into the Unit 2 Annulus Ventilation System filter package, water was discovered in the housings of both filter trains.

The source of the water was determined to be the Make-up Demineralizer Water System (YM), which provides water to filter package loop-seals. The YM source was then isolated.

Further investigation revealed water had entered the Outside Air Pressure Filter Train 2 (VC-B).

Water entered this filter package, a shared unit system, along with other Unit 2 filter packages, by overfilling the level control tanks and backing up the condensate drain lines. The loop-seal level control (McDonnell and Miller, Inc., Model No. 847 Make-up Water Feeder) had been installed in dry lines and allowed to rust, and had not been properly adjusted.

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Report No. 83-06 Page 2 YM system overflow from the VC-B Train level control tank shares a common drain line with other filter package loop-seals. The loop-seals of these Unit 2 filter packages (not yet loaded or in service) were also improperly adjusted, allowing YM system flow to continue even though the loop-seal level control tanks were full. This unchecked flow exceeded the capacity of the 2 1/2" common drain lines, creating the potential for backflow. This was the case in the VC-E Train filter package, where the carbon bed and HEPA filters were damaged.

On 1/26/83, Diesel Generator (D/G) 1A was declared inoperable due to a leaking diaphragm on Fuel Oil Transfer Filter 1A2 isolation valvo 1FD145. The diaphragm 1

was replaced. During the time that maintenance was performed on 1FD145, VC-A 1 rain was declared inoperable due to loss of the emergency bus (supplied by D/G 1A). D/G IA and VC-A Train were returned to operable status on 2/27/83.

Further maintenance work was required on 1/29/83, resulting in D/G 1A and VC-A Train being declared inoperable.

(The leaking diaphragm of 1FD144, the second Fuel 011 Transfer Filter isolation valve, was replaced).

In both cases, the diaphragm had become oil-saturated and began to leak, requiring replacement.

Replacement diaphragms for these 2" Grinnell Diaphragm Values are rated for a five year life.

The Action Statements for Techaical Specification 3.7.6, under which VC-B was declared inoperable, cre segregated into two classes. Action prescribed for Modes 1,2,3 and 4 and that of Modes 5 and 6 are listed separately. Changing modes with VC-B Train declared inoperable was the result of an Operations interpretation of Technical Specification 3.7.6, which does not differentiate between action statements applicable during Modes 5 or 6.

As no differences existed in regards to VC System inoperability for the two modes, the mode change was evaluated as having no effect. However, Duke Power's subsequent reevaluation of the mode change (after Mode 6 had been entered) was based upon the failure of the VC system to meet the Limiting Condition for Operation. This was interpreted as a violation of the Technical Specification for Applicability, 3.0.4.

SAFETY ANALYSIS

As the exact time that water entered the Outside Air Pressure Filter Train 2 cannot be determined, a conservative assumption that the incident occurred with Unit 1 in Mode I should be made. The VC system includes two 100%

filter trains for the purpose of cleaning control room air (1000 cfm recirculating) and introducing clean fresh air (1000 cfm outside) in the case of an accident.

Impairment of this function by wetting the filter components would be minimal.

The removed HEPA filter showed no holes or displacement of media, and would have still performed efficient particulate removal, if required. The wet carbon in the bottom of the bed combined with the wet portion of the HEPA filter would raise the differential pressure across the filter package and thereby reduce design flow rate. By this means, the condition of the filter train could have been discovered had the system operation been required.

In such a case, the redundant train was available for use.

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Report No. 83-06 Page 3 Prior to working on D/G 1A, and disabling emergency power to VC-A Train, Unit 1 entered Mode 5.

Action specified when both VC trains are inoperable in Modes 5 or 6 is the disallowance of positive changes in reactivity or core alterations.

These conditions were met.

Changing modec with one train of VC inoperable had no impact, as the action statament does not change froc Mode 5 to 6.

Operations parsonnel are ucli J

cuare that an increase in operational mode (i.e., proceeding through start-up) requires prior VC system operability.

Ihis incident had no effect upon the health and safety of the public.

CORRECTIVE ACTION

After discovering water-damaged filtcr components in the Outside Air Pressure Filter Train 2, the carbon bed and installed HEPA filters 4

were removed, the filter housing cleaned, and filters reloaded. As water had entered the system by backing up the drain lines, the possibility of line bicekage downstream of the filter packages was investigated. Downstreau drain lines were cut and inspected for obstructions in several places. No obstruc-tions were encountered, and piping was rejoined.

The loop-seal level controls were then checked and found to be improperly adjusted and rusted. This was attribated to their having been installed in dry lines. The aake-up water 4

feeders were cleaned and properly adjusted.

Reloaded carbon and HEPA filters in the Outside Air Pressure Filter Train 2 were tested per "In-Place Test of HEPA and Carbon Adsorber Filters" The system was returned to service on 2/3/83. Proper loop-seal level control was functionally tested by aligning YM supply to the loop and monitoring flow with the instrumenta-tion provided. The loop-seal filled and then allowed no further flow.

In order to eliminate any future confusion arising from a change from Mode 5 to 6, a change in Technical Specification 3.7.6 is being pursued. This change will list an exception to Technical Specification 3.0.4 in the Action Statements for Modes 5 and 6.

This will then explicitly permit such a mode change (in either direction) with a VC train inoperable. The next issue date for Technical Specif1-cations will be prior to Unit 2 fuel' loading.

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