ML20203M583
| ML20203M583 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 04/25/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20203M576 | List: |
| References | |
| NUDOCS 8605010589 | |
| Download: ML20203M583 (4) | |
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UNITED STATES Tg g
NUCLEAR REGULATORY COMMISSION 9y WASHINGTON, D. C. 20565
/
SAFETY EVALUATION RY THE OFFICE OF NUCLEAR REACTOR REGULATION O
SUPPORTING AMENDMENT NO.1 TO FACILITY OPERATING LICENSE NO. NPF-43 DETROIT EDISON COMPANY FERMI-2 DOCKET NO. 50-341
1.0 INTRODUCTION
In its submittal dated December 23, 1985, supplemented by letter dated February 4, 1986, Detroit Edison Company (licensee) oroposed to amend Appendix A, Technical Specifications, to Facility Operating License NPF-43.
The proposed changes would permit the reduction of the source rance monitor (SRM) minimum permissible count rate from 0.7 counts per second Icps) to 0.3 cps for a limited period of time during the first fuel cycle. On April 23, 1986, following a decision to replace the depleting sources prior to restart, the licensee withdrew a portion of its earlier recuest which was not required to support the replacement of the sources.
2.0 EVALUATION The Fermi-2 facility was issued a low power license on March 20, 1985.
Initial criticality with the reactor head installed was achieved on June 21, 1985, and thereafter the plant was operated below five percent of full rated power (i.e.,165 mecawatts) in accordance with its low power license. The full power license for Fermi-2 was issued on July 15, 1985. However, a Confirmatory Action Letter was issued by the NRC on July 16, 1985, confirming the licensee's agreement to limit power to values less than five percent of rated power. The plant was operated at or below this power level until October 10, 1985, when it was shutdown to install various pieces of safety-related equipment. Due to a number of problems, the plant has remained shutdown for the last six months.
As a result of this extended shutdown and the relatively low power levels for the preceding four months, the four neutron sources in the reactor core have decayed to levels where the neutron count rates measured by the source range monitors no longer satisfy the minimum values for operations contained in the Fermi-2 Technical Specifications. To achieve the presently required minimum count rate of 0.7 cos, the sources will have to be replaced. How-ever, some fuel must be moved to replace the sources and the Technical Specifications related to refueling operations also presently require a minimum count rate of 0.7 cps.
For this reason, the licensee has maintained a portion of its original request for limited relief from a surveillance requirement applicable to j
the SRM's in the Fermi-2 Technical Specifications; the affected portions are Specifications 4.3.6 and 4.9.2.
These changes were first proposed in 8605010589 860425 DR ADOCK 05000341 PDR Y
2-the licensee's letter dated December 23, 1985, and later supplemented in its letters dated February 4, 1986, and April 23, 1986. The most recent submittal by the licensee requests that the staff revise only the SRM surveillance requirement and the control rod block instrumentation setpoints for those fuel movements required to replace the neutron sources. The licensee in this recent letter requested that its prior request for a change in Specification 4.3.7.6 not be granted. Accordingly, this evaluation is directed only towards the proposed revisions to Specifications 3/4.3.6 and 3/4.9.2.
The proposed change to Specification 3/4.3.6, Instrumentation / Control Rod Block Instrumentation, would lower the required minimum value o' the SRM trip setpoint and the associated " Allowable Value" from 0.7 cps to 0.3 cps to permit replacement of the neutron sources. Table 3.3.6-2 currently requires, in a footnote for the SRM downscale values (Item 3.d), an SRM neutron count rate of at least 0.7 cps with a signal-to-noise ratio of at least 2.
The proposed change would modify this footnote to indicate that the 0.7 cps reouirement may be reduced to 0.3 cps prior to achieving a burnup of 2000 MWD /T in the first core with a signal-to-noise ratio main-tained at a minimum value of 2.
The licensee has stated in its letter dated April 23, 1986, that this pro-cosed change to Table 3.3.6-2 of Specification 3/4.3.6 will allow perfom-ance of the required SRM functional tests without altering circuits. Any such circuit alteration, even if only for a limited purpose such as replacing the neutron sources, is undesirable in that it introduces the possibiltiy of personnel error in making the circuit alteration and then restoring the circuitry to its original configuration. The proposed change to Specification 3/4.3.6 for a limited time (i.e., replacement of the sources during the first fuel load) introduces less potential risk than the alternative of modifying and restoring the circuitry. More importhntly, l
the proposed change avoids the presence of a continual downscale alarm in the control room, generated by one of the two SRMs at or below 0.3 cps, i
that could mask an anomalous condition in which one of the two SRMs which are presently below 0.7 cps but above 0.3 cos, might go downscale. Because the proposed change maintains the present system of alarms, the change does not alter our prior conclusions regarding corc alterations during refuelino operations. On this basis, the proposed change to Specification 3/4.3.6 is acceptable.
Specification 3/4.9.2, Refueling Operation / Instrumentation, currently requires, in a footnote for the relevant operability surveillance, an SRM count rate of at least 0.7 cps with a signal to noise ratio of at least 2.
(If not, the count rate must be at least 3 cps.) The proposed change would modify the appropriate footnote to indicate that the 0.7 cps requirement may be reduced to 0.3 cps prior to achieving a burnup of 2000 MWD /T in the first core with a signal to noise ratio maintained at a minimum value of 2.
The only core changes pemitted with the reduced SRM count rate of 0.3 cps are those fuel movements necessary to replace the neutron sources.
7 7
. The licensee has demonstrated that the noise signal is normally less than 0.1 cps, detemined with the detectors withdrawn from the core, and that, therefore, the signal to noise ratio is greater than 2 with an SRM count rate of 0.3 cos. This provides assurance that the system is counting neutrons and will respond appropriately to any changes in the neutron flux level. Decreases in the flux level by about a factor of two are of no significance for establishing the initial conditions when analyzino transients from low power levels, i.'e.,
a rod withdrawal or a rod drop.
Conservatively low count rates are assumed in these analyses.
Furthermore, scrams initiated by the SRM's are not assumed in these transient analyses; rather, these transient analyses assume that a scram is initiated by the average power range monitors. Thus, the original safety analyses for low power transients are unchanged by the proposed reduction in the minimum neutron count rate.
We conclude, therefore, on the basis of the precedino discussion, that the proposed reduction in the value of the minimum permissible SRM count rate in Soecification 3/4.9.2, is acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
This anendment involves a chance in the installation and use of. a facility component located within the restricted area as defined in 10 CFR Part 20 and chances in surveillance requirements. The staff has determined that this amendment involves no significant increase in the amounts, and no sionificant change in the types, of any effluents which may be released offsite, and that there is no significant increase in individual or cumula-tive occupational radiation exposure. The Commission has previously issued a proposed finding that this amendment involves no significant hazards con-sideration and there has been no public comment on such findino. Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this, amendment.
4.0 CONCLUSION
The Coamission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal Register (51 FR 3714) on January 29, 1986, and consulted with the State of Michigan. No public coments were received, and the State of Michigan did not have any comments, i
1 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 regula-tions and the issuance of this amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: Howard Richings, NRR Dated: April 25, 1986
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AMENDMENT NO. 1 TO FACILITY OPERATING LICENSE NO. NPF FERMI,llNIT 2 DISTRIBilTION:
,DocketNo850341}h NRC PDR Local PDR PRC System NSIC BWD-3 r/f MDLynch (2)
EHylton (1)
EAdensam Attorney, OELD CMiles RDiggs JPartlow RGrimes EJordan LHarmon TBarnhard (4)
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