ML20126E115

Safety Evaluation Supporting Amend 6 to License DPR-6

ML20126E115
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	07/18/1974
From:	Oconnor P, Ziemann D US ATOMIC ENERGY COMMISSION (AEC)
To:
Shared Package
ML20126E110	List: ML20126E107 ML20126E111 ML20126E115 ML20126E118
References
NUDOCS 8101100862
Download: ML20126E115 (2)

Text

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i SAFETY EVALUATION BY THE DIRECTORATE OF LICENSING

! SUPPORTING AMENDMEKT NO. 6 TO LICENSE NO. DPR-6

,(CHANGENO.43TOTECHNICALSPECIFICATIONS[APPENDIXA])

CONSUMERS POWER COMPANY BIG ROCK POINT NUCLEAR PLANT,

DOCKET NO. 50-155

! Introduction The Consumers Power Company requested by letter dated June 28s 1974, that the Technical Specifications to Facility Operating License DPR-6 be changed to pemit the removal of the four lower rollers from fifteen peripheral control rods. The removal of the rollers is proposed to eliminate the 4

pocibility of vibration induced separation of these rollers from the control rods and possible subsequent control rod jaming. .

Evaluation The effect of the remval of the control rod lower rollers has been evaluated at the Big Rock Point Nuclear Plant during the three months subsequent to April 1974. At that time, the lower rollers on peripheral control rod C-6 were removed to gain operating experience to justify removal of the lower rollers from the fifteen remaining peripheral control rods.

t The operation of the control C-6 without lower rollers has been evaluated for three months and no abnomal operation has been observed. During the evaluation period control rod C-6 has undergone the following tests:

1 scram time test

. 4 full length trip tests

, insert-withdrawal timing tests 4 critical approaches 2 full length normal speed insertions I

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These tests indicated that the removal of the four lowerrollers from control i rod C-8 did not Msult in any degradation of control rod perfonnance. The normal drive speeds or scram times were not significantly changed. The support-tube and fuel channels surrounding control rod C-6 were inspected and no evidence of war was notad on these components.

The number of test operations carried out on control rod.C-6 are approximately the same as the expected number of similar operations anticipated duririg the remainder of the current operating cycle which is expected to end in 1975.

During the'neRfudf06104360tgp peripheral rods and the adjacent fuel channels which have had rollers removed will be inspected for signs of wear.

The Regulatory staff concludes that the testing program conducted by Consumers Power Company has established that the removal of the lower rollers will not degrade the perfomance of the control rods during the remainder of the present cycle. The performance of the control rods will be reevaluated

during each cold shutdown during the cycle and the results compared with previous test results to assure that no unforeseen trends toward degraded perfomance are established.

Conclusion The staff concludes that because (1) the tests performed by the licensee have verified that control rod perfomance has not been degraded by the removal of the lower rollers from control rod C-6; and (2) the inservice inspections currently required by the Big Rock Technical Specifications will provide adequate assurance that no unforeseen trends toward degraded performance develop; and (3) because the change does not involve a significant increase in the probability or consequences of accidents previously considered l and does not involve a significant decrease in a safety margin, the change does not involve a significant hazards consideration; .nd (4) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner.

Paul W. O'Connor I Operating Reactors Branch f2 Directorate of Licensing Dennis L. Ziemann, Chief l Operating Reactors Branch #2

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