05000336/LER-1997-002-01, :on 970108,damper 2-HV-210 Could Not Be Manually Operated within Ten Minutes as Required in Accident Analysis.Caused by Inadequate Evaluation of Mechanical Binding.Damper Was Placed in Fail Open Position

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:on 970108,damper 2-HV-210 Could Not Be Manually Operated within Ten Minutes as Required in Accident Analysis.Caused by Inadequate Evaluation of Mechanical Binding.Damper Was Placed in Fail Open Position
ML20134L418
Person / Time
Site: Millstone Dominion icon.png
Issue date: 02/07/1997
From: Laudenat R
NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20134L411 List:
References
LER-97-002-01, LER-97-2-1, NUDOCS 9702190114
Download: ML20134L418 (3)
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LER-1997-002, on 970108,damper 2-HV-210 Could Not Be Manually Operated within Ten Minutes as Required in Accident Analysis.Caused by Inadequate Evaluation of Mechanical Binding.Damper Was Placed in Fail Open Position
Event date:
Report date:
Reporting criterion: 10 CFR 50.73(a)(2)(i)
10 CFR 50.73(a)(2)(viii)
10 CFR 50.73(a)(2)(ii)
10 CFR 50.73(a)(2)(x)
10 CFR 50.73(a)(2)(iii)
10 CFR 50.73(a)(2)(iv), System Actuation
10 CFR 50.73(a)(2)(v), Loss of Safety Function
10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
3361997002R01 - NRC Website
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NRC FORM 366 U.S. NUCLEAR REGULATORY CoMMISSloN APPROVED BY OMB NO. 3150-o104 (4-95)

EXPIRES 04/30/98 LICENSEE EVENT REPORT (LER)

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digits / characters for each block)

$EE N"I GE E W ND W E"T r"O S

FACILITY NAME (1)

DOCKET NUMBER (2)

PAGE (3) i Millstone Nuclear Power Station Unit 2 05000336 1OF3 TITLE (4)

Damper 2-HV-210 Cannot be Manually Operated within ten minutes as Required in the Accident Analysis l

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EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7) oTHER FACILITIES INv0LVED (8) sE

' AL REV MONTH DAY YEAR YEAR MONTH DAY YEAR NU' BE NU i

l 01 08 97 97

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00 02 07 97 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 5: (Check one or more) (11)

MODE (9) 0 20.2201(b) 20.2203(a)(2)(v) 50.73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(a)(3)(i)

X 50.73(a)(2)(ii) 50.73(a)(2)(x)

LEVEL (10) 20.2203(a)(2)(i) 20.2203(a)(3)(ii) 50.73(a)(2)(iii) 73.71 20.2203(a)(2)(ii) 20.2203(a)(4) 50.73(a)(2)(iv) oTHER 20.2203(a)(2)(iii) 50.36(c)(1) 50.73(a)(2)(v)

Specify in Abstract below

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20.2203(a)(2)(iv) 50.36(c)(2) 50.73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (include Area Codel R. T. Laudenat, MP2 Nuclear Licensing Manager (860) 444-5248 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

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CAUSE

SYSTEM COMPONENT MANUFACTURER

CAUSE

SYSTEM COMPONENT MANUFACTURER PRDS PRDS i

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SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR YES SUBMISSloN X No DATE (15) l (if yes, complete EXPECTED sUBMisslON DATE).

A8STRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewntten lines) (16)

On January 8,1997, at 1230 Hours, it was postulated that the Control Room Emergency Filtration System (CREFS) common inlet damper,2-HV-210, could become stuck closed, causing a single failure that disables both CREFS Facilities. There is no ' hand operator' and the damper is located about 9 feet above the floor, so operations personnel 1

would not be able to open the damper within the 10 minutes required by the control room habitability analysis. The l

Millstone Unit 2 (MP2) accident analysis requires the CREFS to be operating in the recirculation / filtration mode within l

10 minutes of the accident initiation, and takes credit for manually opening the damper if it does not go to the ' fail l

open' position. The FSAR TABLE 9.9-17 ' Control Room Air Conditioning System Failure Mode Analysis" shows the damper (2-HV-210) does not meet the single failure criterion, but that it can be manually opened within 10 minutes, using the ' hand operator'. Emergency operating procedures and annunciator response procedures direct operations to align one Facility of CREFS for operation. The plant was in Mode 6 at 0 percent power at the time of discovery.

j The cause of this event was inadequate evaluation of mechanical binding when the single failure was first discovered and the FSAR revision was prepared in June 1994. Additionally, the ability to manually open the damper r/as not validated.

l The immediate corrective action was to place the damper in the ' fail open' position. An evaluation of 2-HV-210 and itssociated procedures will be performed. Other operator actions which are included in the safety analyses will be r: viewed and validated, as necessary. Design changes and validations which result will be completed before entering Mode 4.

9702190114 970207 PDR ADOCK 05000336 S

PDR-

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. NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSlod (4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET LER NUMBER (6)

PAGE (3) l SEQUENTIAL REVISION YEAR NUMBER NUMBER 2OF3 l

Millstone Nuclear Power Station Unit 2 05000336 97

- 002 -

00 TEXT (!f more space is required, use additional copies of NRC Form 366A) (17) l l.

Desenption of Event On January 8,1997, at 1230 Hours, it was postulated that the Control Room Emergency Filtration System (CREFS) [Vl] common inlet damper,2-HV-210, could become stuck closed, causing a single failure that would disable both CREFS Facilities. There is no ' hand operator' and the damper is located about 9 feet above the floor, so operations personnel would not be able to open the damper within the 10 minutes required by the control room habitability analysis. The Millstone Unit 2 (MP2) accident analysis requires the CREFS to be operating in the j

recirculation / filtration mode within 10 minutes of the accident initiation. The analysis takes credit for operations l

personnel manually opening the normally closed damper, if it fails to go to the ' fail open' position. The FSAR TABLE 9.9-17 " Control Room Air Conditioning System Failure Mode Analysis" shows the damper (2-HV-210) does not meet the single failure criterion, but that it can be manually opened by operations personnel within 10 minutes using the ' hand operator'. Emergency Operating Procedures (EOP) and Annunciator Response Procedures (ARP) contain steps which direct operations to align one complete Facility of CREFS for operation. At the time of discovery the damper was placed in the ' fail open' position. The plant was in Mode 6 at 0 percent power at the time of discovery.

There were no automatic or manually initiated safety systems activated as a result of this event.

ll.

Cause of Event

The cause of this event was inadequate evaluation of mechanical binding when the single failure was first discovered l

and the FSAR revision was prepared in June 1994. Additionally, the ability of operations personnel to manual!y open the damper, when required, was not validated.

l Ill. Analysis of Event This event is isei,a reported in accordance with 10 CFR 60.73(a)(2)(ii)(B) as a condition that is outside the design basis of the plant.

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The most critical need for the CREFS is to protect MP2 control room personnel from exceeding General Design l

Criterion 19 dose limits following a Millstone Unit 1(MP1) Main Steam Line Break (MSLB). The two fresh air inlet radiation monitors initiate CREFS isolation of outside air, places the system in the recirculation / filtration mode, and l

initiates a control room alarm. The ARP directs operations personnel to align one complete Facility of CREFS for operation upon receipt of the alarm. The limiting accident being a MP1 MSLB, MP2 personnel's primary concern i

would be verification and restoration of CREFS. If 2-HV-210 failed to open, the loss of the filtration function could result in increased dose or extended time for control room personnel to wear respiratory protection. Additionally, the damper is required to close in order to purge the control room with fresh air when outside air activity decreases to acceptable levels. Failure of 2-HV-210 to open would not affect the ability to purge.

j in the event of a LOCA in MP2, an Engineered Safety Actuation Signal (ESAS) signal would initiate CREFS and a j

control room alarm. The damper 2-HV-210 could fail to open requiring operations personnol action to restore filtration. Operation of the filtration portion of the system within 10 minutes is less critical since the LOCA analysis uses long term in-leakage as the most limiting dose input for control room personnel.

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, NRC FORM 366A U.s. NUCLEAR REGULATORY COMMISSION

(&95)

)

l UCENSEE EVENT REPORT (LER)

TEXT CONTINUATION l

FACILITY NAME (1)

DOCKET LER NUMBER (6)

PAGE (3) l SEQUENTIAL REVISloN YEAR NUMBER NUMBER 3OF3 Millstone Nuclear Power Station Unit 2 05000336 97

- 002 --

00 TEXT (It more space as required, use additional copies of NRC Form 366A) (17) j Technical Specification Surveillance Requirement 4.7.6.1b requires flow through each filter train every 31 days, on

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a staggered test basis. To perform the tests on the A and B filter trains,2-HV-210 is stroked opened and closed twice each month. A search of the damper maintenance records identified no instance of damper failure. Failure i

of 2-HV-210 to open would disable the filtration portion of CREFS, which filters a 15 percent slip stream flow off of the main flow path. The isolation from outside air and the recirculation portion of CREFS, which provides heating l

and air conditioning of 100 percent of total flow, would not be affected.

The damper receives an open signal from both Facility 1 and Facility 2 and has dual solenoids such that loss of AC i i or DC power, or loss of air will cause it to go to the ' fail open' accident position.

j Based on the above, this event is not considered to be safety significant.

IV. Corrective Action

The immediate corrective action was to place the damper in the ' fail open' position.

l An evaluation of 2-HV-210 and associated procedures will be performed. Other operator actions which are l

included in the safety analyses will be reviewed and validated, as necessary. Design changes and validations I

which result from this review will be completed before entering Mode 4.

V.

Additionalinformation i

l Similar Ev2 DIS l

LER 94-006-00 The A and B Control Room Air Conditioning filter fans share a common suction plenum.

j Opening either filter housing door effectively breaches the CRAC filtration boundary, rendering both CRAC system

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trains inoperable.

1 LER 94-018-00 The CRAC 5!ter fans were feeding the opposite supply trains. A fan fed the B train, and B fan fed the A train, an original design error.

Entrgy Industry Identification System (Ells) codes are identified in the text as [XX].

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t NAC FORM 366A 14-95) r

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