05000255/LER-1980-003-01, During Evaluation of SEP Topic VI-3,incorrect Assumptions for Initiation of Containment Spray Were Determined to Have Resulted in Lower Predicted Peak Pressures.Reanalysis Corrected Calculations

During Evaluation of SEP Topic VI-3,incorrect Assumptions for Initiation of Containment Spray Were Determined to Have Resulted in Lower Predicted Peak Pressures.Reanalysis Corrected Calculations

ML18044A904
Person / Time
Site:	Palisades
Issue date:	05/13/1980
From:	CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML18044A903	List: 05000255/LER-1980-003-01, During Evaluation of SEP Topic VI-3,incorrect Assumptions for Initiation of Containment Spray Were Determined to Have Resulted in Lower Predicted Peak Pressures.Reanalysis Corrected Calculations
References
TASK-06-03, TASK-6-3, TASK-RR LER-80-003-01X, LER-80-3-1X, NUDOCS 8005190474
Download: ML18044A904 (4)

LER-1980-003, During Evaluation of SEP Topic VI-3,incorrect Assumptions for Initiation of Containment Spray Were Determined to Have Resulted in Lower Predicted Peak Pressures.Reanalysis Corrected Calculations

Event date:
Report date:
2551980003R01 - NRC Website

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~DATE TO LER DATED ~4038Q..

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NRC FORM366 17-771 PALISADES PLANT u. ~: Nuci:£~R*REGULA;ro~v'coMM1ss10N

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LICENSEE EVENT REPORT (PLEASE PRINT OR TYPE ALL REOUiRE"o INFORMATIONI CONTROL BLOCK: I IQ 1

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60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION ANO PROBABLE CONSEQUENCES @

1During evaluation of the high energy line break SEP Topic, it was deter-

[QJ1J 1mined that incorrect assumptions for initiation of containment spray as

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1well as inaccuracies in SG mass-energy inventories resulted in predicted

(]JI) 1Peak containment pressures being lower than actual.

The recalculated contain-

£IIIJ I ment pressures would exceed design pressures under certain accident

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I conditions.

Event reportable ~er TS 6.9.2.A.8.

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CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUB CODE SUBCODE JS IB I@ ~@ 1.AJ@) IZ IZ I ZIZ I Z IZ I@ E.J@) fU@

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CODE TYPE I I 10 10 I 31 k::::J p 11 I 1U I.=1 23 24 26 27 28 29 JO 31 REVISION NO.

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I 80 TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM l>UB.

SUPPLIER ACTION FUTURE EFFECT SHUTDOWN

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CAUSE DESCRIPTION ANO CORREC'rlVE ACTIONS.

.&.g 47 Jill] JErrors were apparently made during initial accident analyses.

Corrective IIITI I action __ has *been taken to reduce spray initiation time, and to reduce mass-

((I)) 1energy release into containment following a MSLB.

Calculated containment o::::rIJ 1peak pressures are now acceptable.

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STATUS

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RELEASED OF RELEASE AMvUNT OF ACTIVITY EE] W@ ~@I NA I

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9 10 11 7

METHOD OF DISCOVERY DESCRIPTION @

DISCOVERY LPJ@I SEP Evaluation cs 46 NA LOCATION OF RELEASE @.

45 PERSONNEL EXPOSURES t::;:,.

80 BO 80 NUMBER t:;::;-. TYPE DESCRIPTION\\~

ITEi I 0 I 01 0 '~@,___NA 1

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OESCRIPTION6 ETIJ b 10 I 0*1@~------_N_A ______________________ __,

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TYPE

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I II II II I II II I 68 69 80 so

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consumers Power company General Offices: 212 West Michigan Avenue,.Jackson, Michigan 49201

• Area Code 517 788-0550 May 13, 1980 Mr James G Keppler Office of Inspection & Enforcement Region III*

U S Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-255 - LICENSE DPR PALISADES PLANT - UPDATE TO LICENSEE EVENT REPORT 80-003 -

CONTAINMENT SPRAY

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Licensee Event Report (LER)80-003 was submitted to the NRC Region III office on April *3, 1980.

An update to this LER is on the reverse side of this letter.

Also attached is a two page report which contains the actions taken with regard to this LER.

David P Hoffman (Signed)

David P Hoffman Nuclear Licensing Administrator CC Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement NRC Resident Inspector - Palisades Attachment (2 pages)

Attachment to LER 80-003/01-X-l Consumers Power Company Palisades Nuclear Plant Docket 50-255

Description

During review of SEP Topic VI-3 it was discovered the total activation time for the containment spray was in excess of the initiation times of 30 and 33 seconds published in FSAR, Section 14.18.1.

The time required to fill the pipe headers, in combination with diesel and pump starting times, accounts for most of the difference.

The containment pressure analysis due to a LOCA, described in FSAR, section 14.18, is not considered to be significantly affected by the longer spray initiation since peak pressures occur prior to the assumed shorter spray initiation times.

During a LOCA one of the functions of the sprays is to limit the peak pressure after recirculation occurs, but containment spray does not influence the initial pressure rise.

Peak pressures for MSLB's in the 1969 analysis, summarized in Amendment 14 (item 14.11), occurred after the sprays were assumed to be activated.

The sprays were then-partial cause for limiting the peak pressure during a MSLB.

The MSLB was therefore considered for reanalysis.

Following discussion with Combustion Engineering (CE) and Bechtel to plan corrective actions, CE discovered an error in the 1968 mass release data for MSLB.

This error affects only the reactor full load case and results in approximately a 5% increase in total mass release to containment.

Cause of Deviation The cause of the iricorrectly assumed spray initiation time was an apparent oversight in which the 30 second start time for ESS equipment are closed onto the diesel bus.

Another oversight was apparently-nade in the analysis for mass and energy release performed by CE in 1968.

This error resulted in the published integrated flow from the intact* steam generator prior to isolation being too low.

Corrective Action

Reanalysis of the full load MSLB assuming losS-of offsite power and diesel failure and*using ~orrected spray initiation times showed containment design pressure to be exceeded.

The error in the mass and energy release data accounts for a majority of the calculated pressure increase.

The no-load analysis has assumed offsite power is available which is consistent with the philosophy in the FSAR Amendment 15 Item 14.3 and Amendment 17, Item 5 and 6.

The assumed most severe single active*failure is a containment spray pump failure.

The contributing factors for the no-load results exceeding containment pressure are an apparent overly conservative calculation of no-load steam generator inventory and the stroke time of the containment spray isolation valve *.

Para.metric analysis has been completed assuming varied steam generator water levels, filling the containment spray system headers, and tripping the MSIV in a shorter interval, thereby reducing the mass release from the intact steam generator.

Necessary modifications in plant operation have been made based on this analysis.

These changes will allow the plant to operate within plant design constraints.

.. ~........

The changes are:

(1)

Closure of the MSIVs.on containment high pressure as well as on steam generator low pressure.

In conjuction with this, an analysis has been completed which concludes that MSIV closure will occur in less than 1 second after receipt of the initiating signal.

(2)

Resequencing of loads on the emergency diesel generators,.

such that the containment spray pumps are started sooner.

(3)

Partial filling of the containment spray system piping, in order to further reduce containment spray initiation times.

(4)

Imposition of a 1 psig limit on containment initial pressure.

( 5)

Modification of the containment spray isolation valve actuator to reduce the stroke time and in turn reduce the containment spray initiation time.

Proposed changes to the Palisades Plant Technical Specifications will be submitted to incorporate items (1), (3) and (4) above as_

Technical Specification operability requirements.

It.sh0uld be noted that operating restrictions (1) through (5) were derived from a parametric analysis; accordingly, if operating experience indicates one or more of the restrictions to be unsatisfactory, the analysis will necessarily be reperformed to derive a new set of operating restrictions.

Accordingly, proposed technical specification changes will not be submitted until sufficient operating experience indicates the above restrictions to be acceptable.

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