ML20128D343

Safety Evaluation Supporting Amends 88 & 78 to Licenses DPR-39 & DPR-48,respectively

ML20128D343
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	05/13/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20128D329	List: ML20128D324 ML20128D336 ML20128D343
References
NUDOCS 8505280569
Download: ML20128D343 (2)

Text

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/' NUCLEAR REOULATORY COMMISSION ananssovose, o.c. sones

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTORMEILATION m.

RELATED TO AMENDMENT NO. 88 TO FACILITY OPERATING LICBISE MO. DPR-39 AND AMEN 0 MENT NO. 78 TO FACILITY OPERATING LICENSE WD. OPR-48 i

C0fMONWEALTH EDISON COMPANY ZION NUCLEAR POWER STATION. UNITS 1 AND 2 -

DOCKET NOS. 50-295 Afm 50-304 INTRODUCTION By letter dated August 5, 1982, Commonwealth Edison Company proposed an amendment to Appendix A of Operating Licenses No. DPR-39 and DPR-48. The subject change involve _d Section 3.2.3 of the Zion Technical Specifications.

Th6 licensee had proposed to delete the existing requirement that the Unit be shut down if more than one rod is inoperable due to a rod urgent failure alarm condition. In a Safety Evaluation Report dated June 20, 1983, the NRC found the proposed Technical Specification unacceptable, stating that indefinite operation with control banks C and D locked-up could result in unnecessary safety system challenges if intentional or accidental secondary side power changes occurred. The licensee resubmitted the proposed Technical Specification by a letter dated February 5, 1985. This submittal proposed that if more than one control rod is inoperable due to a rod urgent failure, reactor operations may continue for the succeeding 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or the Unit must be placed in Mode 3 in the next four hours.

EVALUATION -

A rod urgent failure condition indicates that a malfunction has occurred in the electronics of the rod sequencing and coritrol system. In response to the malfunction, the applicable bank (or in some cases, all banks) are " locked up" by sealing in power to both the stationary and moveable gripper coils, thus preventing manual or automatic rod motion. This is done to ensure that the malfunction does not result in dropped rods, or improper rod sequencing, all of which could produce unacceptable flux peaking. An urgent failure condition in no way reflects on the ability of the rod to be scrammed. The rod control system is not a safety system and no credit is taken for it in accident analysis.

Existing Technical Specifications require that the reactor be shut down within four hours if an urgent rod failure condition cannot be corrected within two hours. Since the presence of an urgent failure condition does not indicate that the affected rods are untrippable, the requirements to shut down are not warranted for those rods that are fully withdrawn when the reactor is critical (all shut down banks ano control banks A and E). In this case no safety or control functions are compromised and a forced shutdown would be an unnecessary

- piant transient. However, the malfunction should be corrected as soon as practicable.

8505280569 850513 PDR ADOCK 05000295 p PDR s

- 2-If the urgent failure condition results in lock-up of control banks C or D, these banks would not be able to perform their normal function of adjusting reactor power to match changes in secondary side power. Although no safety functions are lost, operation in this condition should be limited in duration.

Intentional or accioental secondary side power changes could result in a primary / secondary power mismatch causing unnecessary safety system challenges. .During steady state operation, however, the boron addition /

dilution capabili. ties of the plant are more than adequate to compensate for minor reactivity changes.

Allowing operation for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at steady st' ate woulo provide the licensee sufficient time to identify the cause of the rod urgent failure and to tske corrective actions. This change will reduce the number of plant shutdowns and startu;:s and tne ass'ociated plant transients. Operation in this condition does not pose an undue risk since this only applies to electrical failures (as incicated by the rod urgent failure alarm) and the affected control rods would not be mechanically stuck. After 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, the unit would tnen be placed in Mode 3 anc maintenance efforts could continue.

We find the licensee's proposed Technical Specification change to extend reactor operation from 2 to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> with more than one rod inoperable due to a rod urgent failure to be acceptable.

, ENVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of the facilities components located within the restricted areas as defined in 10 CFR 20. The staff has detennined that these amendments involve no

' significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite and that there is no

, , significant increase in individual or cumulative occupational radiation exposure. -The Comission has previously issued a proposed finding that

these amendments involve no significant hazards consideration and there has been no public coment on such finding. Accordingly, these amendments meets the eligibility criteria for categorical exclusion set forth in 10 CFR Sec 51.22(c)(9). Pursuant to.10 CFR 51.22(b) no environmental impact statement i or environmental assessment need be prepared in connection with the issuance of these amendments.

CONCLUSION I

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.

1 Dated: May 13, 1985 PRINCIPAL CONTRIBUTOR:

M. M. Holzmer

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