ML20127J252

Responds to Re High Rate of Power Increase Experienced at Dresden Unit 2 & Monticello.Issue of Rod Withdrawal Sequences Will Continue to Be Evaluated on Generic Basis to Confirm Sequences Allow Operator Action

ML20127J252
Person / Time
Site:	Monticello, Dresden
Issue date:	10/26/1977
From:	Case E Office of Nuclear Reactor Regulation
To:	Deboer T NEW YORK, STATE OF
Shared Package
ML20127J255	List: ML20127J252 ML20127J263
References
NUDOCS 9211190247
Download: ML20127J252 (7)

Text

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Q OCT 2 61977 l*r. T. K. DeBoer, Director Technological Development Programs State of New Yort Energy Office Swan Street Building, Core 1 - 2nd Floor Enpire State Plaza Albany, New York 12223

Dear Mr. DeSoer:

This is in resconse to your letter of tiay 31, 1977 concerning the high rate of power increase (short periods) experienceo at the Drescen Unit Ho. 2 and Honticello boiling water reactor facilities. We appreciate ano share your interest in these events.

Although neithe of the events involvea violation of a technical specification limit, fuel damage, or personnel radiation exposure. we have initiated measures to ninimize the oossibility that sinilar events will occur in the future.

Our interest in tnese events parallels yours and involves both the short reactor oericas, which were the result of unusually hion control roa noten worths, and the potential effects of high control rod worths on noiling waste reactor accident analyses.

We nave concluceu that the available redundant reactor trip capaoility durina startup provides safe temination of power excursions of the type encounterec at ureseen Unit No. 2 and Monticello independent of action by the operator. Nevertheless, we believe that the operator should be able to control nower chances resulting from allowed control roa novenents; ano, tnerefore, we have reconcended to noiling water reactor licensees, via IE Circular 77-7, neasures to avoid short reactor oerions and are continuina to investigate means of limiting the differ-ential worth of control rods to prevent the recurrence of short reactor periods. Specifically, we have contacted the General Electric Company, tne unlR vendor, and have been advised that new procedures have been issued to owners of operating BilRs which result in reducea control rod noten vorths. uhile we are continuing to review this issue, we exoect that the new control rod withdrawal procedures snould reduce control rod noten wortns as well as total control rod worths.

Le will continue to evaluate, on a generic basis, the issue of roo witharawal secuences to confirn that the sequences used at TMs will allow proper operator control of reactivity channes and that potential drcoped rod worths are eithin acconta' le linits, o

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Mr. T. K. DeBoer OCT 2 6 577 For your infomation, we have attached a copy of the-IE Circular and the General Electric Company's_ letter discussed above. Thank you for your interest in this matter and feel free to contact n: should you-have additional questions.

_ Sincerely.

0@a15 ped 95 E. G Case Edson G. Case, Acting Director Office of Nuclear Reactor Regulation

Enclosures:

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---s Mr. T. K. Decoer, Director Tecnnological Development Prograas State of tiew Yorx Enercy Office Swan Street Building, Core 1 - 2nd Floor Enpire State Plaza Albany, t;ew York 12223

Dear fir. DeBoer:

This is in response to your letter of May 31, 1977 concernine the high rate of power increase (short perioos) experienced at the Dresaen Unit No. 2-and lionticello noiling water reactor facilities. He appreciate ano share your interest in these events. Although neither of the events involveo violation of a technical specification linit, fuel damano, or personnel radiation exposure, we have initiated neasures to nininize the possibility that sinilar events will occur in the future.

Our interest in these events carallels yours and involves both the short reactor pericas, which were the result of unusually nich control roc noten worths, and the potential effects of high control rod worths on ooilinq uaste reactor accident analyses.

We nave concludea that the availaule reaundant reactor trip capability during startun provides safe ternination of power excursions of the type encountered at Dresoen Unit lio. 2 and Monticello indepenaent of action by the operator. hevertheless, we believe that the oceratcr should be able to control power cnanges resulting from allowed control roc novements; ano, therefore, we have reconmended to boiling uater reactor licensees, via IE Circular 77-7, m.easures to avoia short reactor rertoos and are continuina to investigate neans of lioitinn the differ-antial vorth of control rods to prevent the recurrence of short reactor periods.

Specifically, we hsve contactec the General Electric Conoany, the SWR vendor, ana have been aavised that new proceaures have been issued to owners of operatina 311Rs 'inich result in recuced control raa noten worths.

1hile se are continuina to review this issue, we exoect that the neu contr)1 roa uittraual creceaures sneuld reduce contral eco noten "ortns as nell as total contrel rod wortas.

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i i'r. T. K. Dedoer Ue will continue to. evaluate, on a generic basis, the issue of rod withdrawal sequences to confim that the sequences used at BWRs will allcw proper operator control of reactivity changes and that potential dropped rod worths are within acceptaDie linits.

Thank you for your interest in this matter and feel free to contact ne should you have additional questions.

i Sincerely, 4

Edson G. Case, Actina Director Of fice of Nuclear Reactor Regulation DISTRIBUTION Dockets 50-263/237 NRC PDR (2) w/ incoming Local PDR (2) w/ incoming ORB #2 Reading VStello EGCase DCrutchfield RBoyd HDenton Rheineman DDavis KRGoller.

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Mr. T. K. DeBoer, Director Technological Development Progratis State of tiew York Energy of fice Swan Street Building, Core 1 - 2nd F1oor Empire State Plaza Albany, tiew York 12223

Dear "r. DeBoer:

This is in response to your letter of May 31, 1977 concerning the high rate of power increase (thert periods) experienced at the iiresden Unit no. 2 ano Ilonticello boiling water reactor facilities. Ve appreciate and share your interest in these events. Altnough neither of the events involved violation of a technical specification linit, fuel.tanace, or personnel radiation exposure, we have initiated ceasures to rinircize the possibility that similar events will occur in the future.

Our interest in tnese events paralicis yours ano involves both the short reactor periods, which were the result of unusually nign control rod notch worths, and the potential effects of high control rod uorths on coiling w& tar reactor accident analyses.

?!c have concluded that the available redundant reactor trip cacaoility durina startup provides safe termination of power eFCursions of the type encountered at Cresden Unit No. 2 and Fonticello innependent of action ny the operator. tJevertheless, we believe that the operator should be able to centrol power changes resultinq from allowed control rod novenents; ano, therefore, uc have recorriended to noiling water reactor licensees, via IE Circular 77-7, nessures to avoid snort reactor periods and are continuing to investicate means of liniting the differ-ential worth of control roos to prevent the recurrence of short reactor periods.

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witharawal saouences to confirm that the sequences resulting from the -

IE circular will allow proper. operator control of reactivity changes 4

L and that potential dropped rod wortns are within acceptable limits.-

Thank 'ou for your interest in this natter and feel free to contact me j

j should you have additional questions, i

j Sincerely, i

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i Edson G. Case,- Acting Director DISTIRBUTION:

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a Thank you for your interest in this matter and please feel free to contact me should you have additional questions.

Sincerely, Edson G. Case, Acting' Director Office of Nuclear Reactor Regulation e

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