ML20125D563

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Informs of Change 8 to License DPR-11,allowing Reactor Startup W/Min Startup Channel Neutron Count Rate of 1/3 Counts Per Second Under Certain Conditions
ML20125D563
Person / Time
Site: 05000130
Issue date: 04/29/1966
From: Boyd R
US ATOMIC ENERGY COMMISSION (AEC)
To: Mcelroy D
NORTHERN STATES POWER CO.
Shared Package
ML20125A538 List:
References
FOIA-85-54 NUDOCS 8506120403
Download: ML20125D563 (3)
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UNITED STATES LI ATOMIC ENERGY COMMISSION p

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Northern States Power Company a

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Minneapolis , Minnesota 55401

- Attention: Mr. David F. McElroy Change No. 8 Vice President - Engineering \

Gentlemen:

By application dated March 14, 1966, the Northern States Power Company (NSF) requested authorisation of a change in the Technical Specifica-tions of License No. DPR-11 pursuant to the provisions of Section -

50.59 of the commission's regulations. This request would permit startup of the Fathfinder reactor with a minimum startup channel neutron count rate of 1/3 counts per second (eps) under certain condi-tions. We have designated this request, as revised in discussions i with NSP, as Proposed Change No. 8.

We have been informed that this change was requested because the extended startup program associated with the conservative approach to operation of the superheater results in decay of the neutron source such that a minimum count rate of 2 eps may not be achievable during startup at times throughout the life of the plant. The low count rate is a result of the high neutron httenuation due to the water in the refalector between the core and the detector.

Based on our review, we have concluded that Proposed Change No. 8 does not present significant hasards considerations not described or implicit in the hasards summary report and that there is reasonable assurance that the health and safety of the public will not be endangered. A related Safety Evaluation is attached.

Accordingly, the Technical Specifications (Appendix A) are hereby changed as indicated .in Attachment A.

Sincerely yours.

Original SicncTc-

. 8506120403 850214 R. L. Doan F0 85,yA pgg R. L. Doan, Director Division of Reactor Licensing Enclosures As stated above 12.

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( l APR 2 91966 AmCM A

[' NORTHERN STATES POWER C(MPANY

, CHANGES TO TECHNICAL SPECIFICATIONS CHANGE NO. 8 - LICENSE NO. DPR-11 (1) Add the following to Section 6.1.8(a): *  ;

"This interlock may be bypassed manually with the use of a key switch to:

  • I (1) permit control rod latching and unlatching as approved by the Operations ,

comunittee ,  ;

(2) permit use of low count rate procedure or other supervised tests approved by the Operations Comittee and in accordance with these Technical Specifi-cations."

(2) Add the following to Section 7.6.2(d):

"In the event that the source strength is insufficient to produce a count rate of 2 eps due to neutrons on the out-of-vessel detectors in the startup channels, .

approach to criticality may be accomplished provided the count rate is greater than 1/3 eps due to neutrons and the following conditions are adhered to:

(1) Prior approval of all procedures and methods of analysis for the specific startup shall be obtained from the Operations Committee and the Safety Committee.

(2) A qualified staff engineer shall be present in the control room during startup.

(3) No changes which could significantly affect reactivity shall have been made to any of the core components or to the core configuration since core reactivity was last correlated with rod position. The specific rod withdrawal sequence used in the correlation shall be used for this type of startup.

(4) If changes which affect reactivity have been made to the core or any of its components, or the rod withdrawal sequence is changed, or more than 4 months have elapsed since shutdown, new correlating data shall be obtained. If in-vessel detectors are used, they shall provide a minimum count rate of 2 cys.

(5) The noise level of the detectors and associated electronics shall be less than 1 cys.

(6) No reactivity increment shall exceed 1/3 the extra.polated snount to critical. There shall be at least a 2 minute wait before addition of the next increment is initiated. Plots of multiplication versus rod position shall be made; and enough counts shall be taken after each increment on a -

t scaler to provide 10 percent statistics until the core reactivity is 0.98,

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" and to provide 3 percent statistics thereaf ter. The count rate shall exceed 2 cps when the core reactivity is 0.995. Af ter the count rate exceeds 2 cps normal startup procedures may be used.

(7) Single coincidence in the startup channel short period scram circuit shall be provided.

(8) Any significant deviation from the correlated data during startup shall require an immediate reactor shutdown until the cause of the discrepancy i is determined."

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