ML18219D857

12/22/1977 Letter Limited Boron Dilution Accident at an Operating PWR Facility Due to Inadvertent Injection of a Portion of the Coolant System While the Reactor Was in the Cold Shutdown Condition

ML18219D857
Person / Time
Site:	Cook
Issue date:	12/22/1977
From:	Tillinghast J American Electric Power Service Corp
To:	Case E Office of Nuclear Reactor Regulation
References
Download: ML18219D857 (8)

Text

DISTRIBUTION AFTER ISSUANCE OF OP TING LICENSE NRCFQRM 195 U.S. NUC! EAR AEQUI ATORY COMMISS OOC ~QB I2 78I iW C I.E NUMB NRC DISTRIBUTION FDR PART 50 DOCKET MATERIAL TO." Mr>> Edson G~ Case FROM: DATE OF DOCUMENT American Elect Power Svc>> Corp>>

2 2 New York, N Y 10004 DATE RECEIVED John Tillinghast 12 3 MLETTER ClNOTORIZEO PROP INPUT FORM NUMBER OF COPIES RECEIVED

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'ESCRIPTION ENCI OSURE Consi sts o f evaluhtion regardi g a potential limited boron dilution dent an operatatigg PWR facility due to he acc't indadvertent injection of a portion of the coolant system .wh1;le the reactor was i 'he cold shutdown condition ~ >>w/att figure 1 of a schematic of the piping arrange ent from the spray additive tank to its va ious discharge points, ~ ~ ~ Notorized 12/22/77 2p + 1p PLAh~ NAME.. DONALD C COOK UNITS 1 & 2 jcm 01/03/78 r &~~M FOR ACTION/INFORMATION BRANCH CHIEF: 7 e

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1000'212) 422.4800 JOHN TILLINGHAST Vice Chairman Engineering and Construction December 22,'977 Donald C. Cook Nuclear Plant Units Nos. 1 and 2 Docket Nos. 50-315 and 50-316 DPR No. 58 CPPR No. 61 Mr,. Edson G. Case, Acting Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Att: Don K. Davis, Acting Chief Operating Reactors Branch 2.

On September 21, 1977, we received Mr. Don K.

dated September 15, which transmitted details of Davis'etter a limited boron dilution accident at an operating PWR facility due to the inadvertent injection of a portion of the coolant system while the reactor was in the cold shutdown condition. This letter further requested that we perform an analysis to evaluate the potential for and consequences of such a boron dilution accident at the Donald C. Cook Nuclear Plant.

The above referenced letter indicated that this accident was caused while performing surveillance testing of the NaOH tank isolation valve, with the decay heat removal system lined up for reactor coolant recirculation. Upon resumption of coolant rec'irculation this NaOH was injected into the reactor coolant system.

In response to the above request we have investigated the potential for such an accident at both units of the Donald C. Cook Nuclear Plant. The results of this invest-igation are given below.

Attached Figure 1 is a schematic of the piping arrangement from the spray additive tank to its various discharge points.

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The diagram represents the valving arrangement for the ECCS during recirculation. The schematic shows that a single valve failure or misposition will not lead to direct injection of NaOH in the Reactor Coolant System.

The spray additive tank contents can only be added to the Reactor Coolant System by the mispositioning of four (4) valves in series, namely, tank discharge valve, 2 locked-closed hand valves and the ECCS pump suction valves from the refueling water storage tank. Thus, our evaluation has clearly shown that. multiple component failures and/or operation errors would be required to initiate the incident cited by Mr. Davis'etter.

Based on this evaluation, it is concluded that this incident could not occur at Donald C. Cook Nuclear Plant by the misposition of a single isolation valve or a single active failure of a component. Hence no corrective action is considered necessary to mitigate the concerns addressed by Mr. Davis'bove referenced letter.

Very truly yours, JT: dp Sworn and Subscribed to before m this wz"+day. of December 1977 in New York County, New York Notary Public TEILEFN gARR~

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