ML20127J263

Raises Concerns Re Excessively High Rates of Power Increase During Reactor Startups at Facilities

ML20127J263
Person / Time
Site:	Monticello, Dresden
Issue date:	05/31/1977
From:	Deboer T NEW YORK, STATE OF
To:	Case E Office of Nuclear Reactor Regulation
Shared Package
ML20127J255	List: ML20127J252 ML20127J263
References
NUDOCS 9211190250
Download: ML20127J263 (2)

Text

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STATc OF New YORK l

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31, 1977

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v1 fut Mr. Edson Case Acting Director Q

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Office of Nuclear Regulation d

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20555 3

Reactivity Additions Duringgeactoir.

Subject:

Startups Q

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Dear Mr. Case:

4 Recently, Dresden Unit 2 and Monticello experienced excessively high rates-of power increase (short periods) during reactor startups. These rapid =

power increases were caused by high control rod notch worths with the reactor in a peak xenon coa h tion.- In both cases the power transient was - terminated by an automatic Intermediate Rate trip.

On April 14, 1977 the NRC issued I'E Circular 77-07 which discussed the Monticello and Dresden incidents and recommended the following actions:

"These events indicate a need for all Mensees of. operating BWRs_ to review their startup procedures and practices' to assure that' their operating staff has adequate information to perform reactor-startups avoiding _ such short periods in the event that the above-described conditions of -peak xenon-with no moderator voids exist at the_ time _ of 'startup. Operators-should be_made aware _ that extremely high rod notch worths can be encountered under these -

condit ions._ The procedures should' include requirements for.a thorough assessment following the occurrence of a short period before any further rod withdrawals are made. These considerations should be included-in the operator training _and requalification= training programs".

We are frankly disturbed by these '111 defined recommended actions which j

essentially permit reactors to continue' to operate with control rod patterns and y

rod notch worths which, in the abseue of equipment failure or ' operator error, _

.g could result in short reactor periods which the operator:cannot control. We strongly feel that under no: circumstances during _ normal operations should the withdrawal of any rod be permitted if it'will result in an uncontrollable power 1

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excurs ion.

9211190250 771026

.PDR ADOCK 05000263 S

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i Mr. Edson Case

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thy 31, 1977 Acting Director What is most disturbing about the NRC position is its apparent reliance on the automatic protection system (intermediate rate trip in this case) instead of insisting that design changes be made or that technical specifications and procedure changes be adopted that would specifically preclude the use of certain control rod patterns and limit the amount of reactivity that can be added by moving a rod one notch at any time during normal reactor operation.

The operator has been and sh ild be the first level of protection, with the j

4 automatic protective system es a 'oackup to respond to abnormal events. An operator has the right to expect that actions he takes which are permitted by the technical specifications will not result in an uncontrollable situation and l

the necessity of automatic protective actions.

It is therefore requested that the NRC require that appropriate changes be j

made in the technical specifications and operating procedures or the design of boiling water reactors to ensure that the amount of reactivity added via control i

red movement during normal operations is limited to that which will result in a rate of power increase which is readily controllable by the operator.

The NRC should also review the maximum and minimum rod worth values used in accident analyses for.'ndividual BWRs to ensure that.in all applicable cases the rod l

worths used are greater than (or where appropriate less than) those which could occur during any xenon condition at any time during a fuel cycle.

Sincerely, i

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' T. d7 D Boer, Director l

TKD:mfh Technological Development Programs cc: Mr. Myer Bender, Chairman, ACRS e

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