ML20092C434
| ML20092C434 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 06/06/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20092C425 | List: |
| References | |
| TAC-54237, TAC-54238, NUDOCS 8406210178 | |
| Download: ML20092C434 (9) | |
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UNITED STATES
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8 NUCLEAR REGULATORY COMMISSION o
2 wAsmNGToN, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0. 44 TO FACILITY OPERATING LICENSE N0. NPF-2 AND AMENDMENT N0. 35 TO FACILITY OPERATING LICENSE NO. NPF-8 ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PLANT, UNIT NOS. 1 AND 2 DOCKET NOS. 50-348 AND 50-364 INTRODUCTION By letter dated February 17, 1984, supplemented'May 3, 1984, Alabama Power (the licensee) requested a change to the specification for the Limiting Conditions for Operation (LCO) for the reactivity control systems.
Specification 3.1.3.1 sets forth those actions which must be taken when a full Length movable control rod assembly is in-operable.
The definition of an operable component is addressed in the section 1.0 of the Technical Specifications and inclu-des the operability of atL controls required for the component to pe rf orm its function.
With regard to the specification for movable control rod assemblies, the definition of operability includes the rod control system.
The rod control system performs those actions which are re-i quired to position the movable control rod assemblies for re-a ctivi ty control but it is not directly involved with the performance of any safety actions for mitigating the conse-quences of transients or accidents.
As such the rod control system is classified as a nonsafety-related system.
8406210178 840606 DR ADOCK 05000348 p
. A feature of the rod control, system is the capability to de-tect malfunctions of electrical components that are used to control the position of the control rod assemblies.
When a malfunction occurs, a " rod control urgent failure alarm" is annunciated in the main control room.
Subsequent movement of the selected bank of control rod groups by either manual or automatic control is prevented by an interlock within the
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rod control system.
Therefore,.the control rods in the group associated with the bank selected are inoperable based on the definition of operable control rod assemblies.
The present action statements under the LCO address the situa-tion where more than one full Length rod is inoperable or mis-aligned.
In this case the unit must be in hot standby in the fotLowing six hours.
In this operating mode the LC0 on movable control rod assemblies is no longer applicable.
Therefore, operation in this mode may continue until the rod control sys-tem is returned to an operable status.
This action would then 1
permit the unit to return to power operation.
The Li censee h as propos ed to include a new action statement to a dd re s s the inoperability of the movable control rod assen-blies due to failures associated with the rod control system.
This action would allow 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to perform any required maintenance to restore the system to an operable status and
wouLd only be applicable if the inoperable control rods are capable of insertion on a reactor trip.
EVALUATION As justification for the proposed change in the LCO for oper-able control rod assemblies, the Licensee provided a descrip-tion of rod control system and the conditions under which a
" rod cont rol urgent failure alarm" could occur.
Within the power cabinets of the rod control system the capability is provided to detect component failures.
The functions inclu-ded in the failure detection circuits are:
regulation fail-ure, phase f ailure, Logic error, multiplexing error and miss-ing ci rcuit cards.
Likewise, the Logic cabinet includes sin-ilar failure detection circuits.
When any of these failures occurs, the rod control urgent failure alare is annunciated j
in the control room and interlocks block subsequent control rod movement.
Due to the types of failures which result in the rod control
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urgent failure alarm, the Licensee concludes that this condition is onLy indicative of problems associated with the rod control system and is not an indication that would preclude the capability for control rod insertion on a reactor trip.
Based on our review of this matter, we concur with the Licensee's conclusion that the rod control 1
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. 1 urgent failure alarm is an indication of a control system i
failure and is not related to control rods being untrip-pable.
Therefore, it is proposed to add an action statement to the LCO for movable control assemblies that would atlow 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> I
for maintenance of the rod control system before action would be required to place the unit in hot standby.
The time allow-ed f or maintenance was based on an analysis of actions which may be required to restore the rod control system to an oper-able status.
As further justification of the proposed change, the Licensee 1
notes that the limitations imposed by the current action state-ments have a negative impact on plant safety since maintenance on the rod control system would take place concurrent with those actions required to assure that the unit is in hot stand-by within six hours.
With a portion of the rod control system inoperable, unit shutdown would not be carried out in the normal manner and imposes additional operating precautions.
Since the inoperability of the rod control system does not pre-sent an immediate concern with regard to the capability of safety systems, we conclude that it is prudent not to require
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actions which could lead to unusual operating circumstances.
The proposed changes to the LC0 are the folLowing 1.
The current action statement (b) would be modified to address only misaligned full Length rods.
(Inoperable full Length rods are addressed by the new action state-ment.)
2.
A new action statement (c) would be added as folLows:
"With more than one full Length rod trippable but inoper-able for greater than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, be in HOT STAN08Y with in the fotLowing 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />."
E The scope of " full Length rods trippable but inoperable" is broader than that encompassed by control rods which are inoper-able due to the interloc4 associated with the rod control fail-ure urgent alarm.
In this regard the Licensee addressed the means available to distinguish whether inoperable control rods are trippable or not.
Test points are Located in the power cabinets for the rod control system which permit monitoring of the electrical current to coils in the control rod mechanism.
If this data shows that the rod control system does not very the current to the mechanism cotts, the problem is isolated to failures in the rod control system.
In this case it would be obvious that the malfunction is due to component fattures 1
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m 6-associated with the rad control system and not related to control rods being untrippable.
Therefore, the new action statement would allow 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> for any repairs before action is required to place the unit in hot standby.
However, if the data on mechanism coit currents showed changes due to the action of the rod control system the problem could be due to a malfunction in either the rod control system or the control rod mechanism itself.
In this case 'it would not be obvious that the control rods are trippable and the unit would be placed in hot standby within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> of having entered the action statement.
The Technical Specifications require that full Length rods shalL be within +12 steps (indicated position) of their group counter demand position.
If one full Length rod does not sat-isfy this requirement, action statement (d) specifies the con-ditions under which continued power operation is permissible.
Action statement (d) also addresses the case where one full Length rod is inoperable due to causes other than addressed by action statement (a).
Action statement (a) requires that the unit be placed in hot standby if one or more full Length rods are inoperable due to being immovable as a result of ex-I cessive friction or mechanical interference or known to be untrippable.
Thus, it is concluded that the present techni-cat specification permit an assessment of whether full Length l
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rods are trippable and that the manner in which this is ac-complished is identical to th$t indicated for the proposed technical specification change related to more than one full length rod being inoperable but trippable.
Therefore, we find that the proposed change does not require judgements on full Length rods being trippable which are not already inherent in the existing action statements.
Therefore, based on this review we conclude that where the in-operability of control rod assemblies can be positively identi-fled as being associated with malfunctions internal to the rod l
control system, it is acceptable to allow adequate time for maintenance before requiring that' the unit be placed in hot standby.
However, we find that a more explicit clarification of control rods being immovable due to rod cont rol system fail-u res should be incorporated in the proposed technical specifi-cat ion change.
We have discussed this matter with the Licensee and have reached a mutually ag reea b le revision of the proposed action statement.
By letter dated May 3,1984, the license revised its orig 1nal proposal as follows and noted that the intent of the previous submittal has not been altered by this clarification. We consider this change i
non-substantive in nature.
The revised statement is:
"c.
With more than one full Length rod inoparable due to a rod control urgent failure alarm or obvious elec-trical problem in the rod control system for greater than 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, be in HOT STAND 8Y within the folLoving 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />."
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-g-Further, the licensee proposed to add the following to the BASES for the Technical Specification on movable control rod assemblies:
"For purposes of determining compliance with Tech-nical Specification 3.1.3.1, any inoperability of full length control rod (s), due to being immovable, invokes ACTION statement "a".
The intent of Technical Specification 3.1.3.1 ACTION statement "a" is to ensure that before leaving ACTION statement "a" and utilizing ACTION statement "c" that the rod urgent failure alarm is illuminated or that an obvious electrical problem is detected in the rod con-trol system by minimal electrical troubleshooting techniques.
Expeditious action will be taken to de-termine if rod immovability is due to an electrical problem in the rod control s'y s t e m.,"
Thus, if more than one full length rod were inoperable due to being immovable and the cause has been determined to be a re-sult of failures or problems internal to the rod control sys-tem, continued operation would be permitted for up to 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> since the cause of inoperability is not related to full length rods being untrippable.
With regard to action statement (d), it is noted that when a single full length rod is inoperable or misaligned, continued operation is permitted if the remainder of the rods in the group are aligned to within 112 steps of the inoperable rod.
In this case the action statement may be satisfied and no limit is specified in which the inoperable rod must be re-stored to operable status.
Further, the conditions specified under which continued operation is permissible with a misalign-of greater than 112 steps in action statement (d) also_do ment not impose a time limit in which the inoperable rod must be re-stored to operable status.
Therefore, it is concluded that 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> for maintenance of the rod contr,ol system in the case in
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which two or more rods' are inoperable but trippable is not unreasonable in contrast to no specified Limit for the case where only one rod is i nop e ratrL e.
SAFETY
SUMMARY
In conclusion we find that the proposed changes, as modified and with the additional clarification of the BASES for the Tech-nical Specification on movable control rod assemblies are ac-ceptable.
ENVIRONMENTAL CONSIDERATION We have determined that these amendments do not authorize a e ange in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact.
Having made this determination, we have further concluded that the amendments involve an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 651.5(d)(4), that an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of these amendments.
CONCLUSION We have concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Dated: June 6,1984 Principal Contributors:
1 T. Dunning M. Dunnenfeld