ML19354C304

Discusses Safety Concern Re Waterhammer Events Identified in Lwrs.All Damaging Waterhammer Events in safety-related Sys or Sys Affecting safety-related Sys Should Be Reported. Crear,Inc Rept & Rept Format Encl.W/O Rept

ML19354C304
Person / Time
Site:	Arkansas Nuclear
Issue date:	09/02/1977
From:	Desiree Davis Office of Nuclear Reactor Regulation
To:	Cavanaugh W ARKANSAS POWER & LIGHT CO.
References
NUDOCS 8004230598
Download: ML19354C304 (3)

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Docket No 50-313 SEP z 1977 m

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Arkansas Power & Light Company

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ATTH: Mr. Willian Cavanaugh t.::

Executive Director, Generation m-and Construction Post Office Box 551

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F5 Little Rock, Arkansas 72203 THL, OOCUMENT CONTAINS m

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POOR QUAUTY PAGES d h

RE: ARKANSAS iWCLEAR ONE rn The 12C staff continually reviet.'s experience fron operating reactors to assure that an adequate level of safety is maintained at each individual

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nuclear plant and fer the total population of nuclear plants. As new E==

technical infomation and operating experience becmes available, the

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HPC evaluates whether such inforcation could significantly alter the it :s previously determined levels of safety.

In this regard, ec have noted I

that there have been about 50 reported water hanmer events in light water h

reactors scne of vehich resulted in structural danage to safety significant systens. Of these, approximately 20 water banners have cccurred due to the rapid condensation of steaa in feedvater lines in plants with bestinghouse r..

and Combustion Engineering designed stean generators. While for the most

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part damage fraa these events has been limited to piping supports one p

event in the feedwater line of a pressurized water reactor did re:. ult in F

a significant piping failure. !!one of the events to date has resulted in an adverse fepact on the health and safety of the public.

It is posst.le,

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however, that water hacc.ers could lead to core severe consequences; although L.s it would t:e expected that the probability of such events is very low.

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Because of the continuing occurrence of water hammer events, the IRC staff I==

hos Decn evaluating available operating experience, actively discussing F-with nuclear stcaa supply vendors and architect /engineerf~g firns 'says of reducing the frequency and conscquences of such events, and utilizing technical consultants te more definitely examine water hanner phenomena.

E A copy of the report of our principal consultant, CREARE, is attached I'

(Enclosura 1) for your infomation.

i As a result of our ef forts to date, we believe that water hamers dee to I

pyy the rapid condensation of stea, in the feedwater lines of stean genorctors p

represent a safety concern. Accordingly, licensees of facilities with N

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ars.ansas Pcwcr s Light Ccapany SEP 2 1977 lq 77 Westingbouse or Cor.bustion Engineering design steam generators are being requested to take further actions, including possible design nocifications, to assure an acceptably low risk to the health and safety of the public from such events.

Your facility is not included in this category since it utilizes D&W steam generators which have not exhibited a propensity for water ha:mers based on operating

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experience to date.

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7 The staff will continue to nonitor operating experience to assess the possible effects of water harr.er on the safety of nuclear power plants. While existing Technical Specifications contain reporting

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requirenents applicable to water hammers, the staff has developed

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additional guidance regarding the type of events to be reported.

Specifically, all danaging water hanner events occurring in safety-related systens, or occurring in other systens that affect safety-related systens, should be reported. A format for the reports is enclosed. Danaging water hanner events are those events that result in:

(a) danage to pipe supports or pipe insulation, (b) pipe displacecont, or (c) failure of pipes or ccaponents.

Apprcved by MO, B-lE0225 (R0072), clearance expires July 31, 1980.

Approval was given under a blanket clearance specifically for identified generic problems.

I Sincerely, Don K. Davis, Acting Chief

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Operating Reactors Branch #2 Division of Operatinc Reactors DISTRIBUTION j

Enclosures:

Docket i

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Report by CREARE on NRC PDR Water Hancer Phennuena Local PDR p

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Forcat for Report ORB #2 Reading DKDavis

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ENCLOSURE N0. 2

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Report of Water Hammer

((y ;.y Plant Name and Unit No.

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Date and Time of Occurrence Operational Mode

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" Plant Systems Affected:

Reactor Coolant Aux. Feedwater RHR Containment Spray ECCS Component Cooling Main Steam Service Water Main Feedwater Other Systems Cause of Water Hammer Rapid Condensation Pump Start Voided Pipe Rapid Valve Motion Water Entrainment Operator Error Other Instrument readings and other observations that indicate the probable cause and effects of the water hammer:

. Description of Damage:

• Corrective Action:

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