ML20196D717
| ML20196D717 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 12/07/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20196D706 | List: |
| References | |
| NUDOCS 8812090169 | |
| Download: ML20196D717 (3) | |
Text
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UN TED STATES
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NUCLEAR REGULATORY COMMISSION n
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMEN 0 MENT NO.156 TO FACILITY OPERATING LICENSE NO. OPR-49 IOWA ELECTRIC LIGHT AND POWER COMPANY CENTRAL IOWA POWER COOPERATIVE CORN BELT POWER COOPERATIVE DUANE ARNOLD ENERGY CENTER DOCKET NO. 50-331
1.0 INTRODUCTION
By letter dated August 29, 1988, Iowa Electric Light and Power Company submitted a request for revision of the Technical Specifications, Appendix A to Operating License DPR-49 for the Duane Arnold Energy Center.
This proposal reflects changes to Sectier. 2.2 of the Technical Specifications to revise setpoints for i
Uninterruptible AC and Instrument AC electrical systems undervoltage relays.
This change has been proposed to meet commitments to upgrade power sup(plies forR.G instrumentation used to meet the recommendations of Regulatory Guide In order to provide upgraded Class 1E power supplies, the licensee intends to replace the existing Uninterruptible AC system motor-generator set and the two Instrument AC system transformers (120/240 VAC split-phase power sources) with independent 120 VAC single-phase static inverter power sources. The planned modification consists of replacing each of the three existing power supplies with static inverter-regulating transformer pairs with static switches.
Each new power supply will have two independent power sources; normal power supplied from existing 480V motor control centers and backup DC power from battery chargers or batteries (125V for the Instrument AC systems, 250V for the Uninterruptible system). The static switches will automatically transfer to the available power source, thus all three of the new power supplies will be "uninterruptible".
Consequently, the existing cross-tie capability between the Instrument AC systems arid between one Instrument AC syst m and the Uninterruptible AC system will be disabled, in order to meet Class 1E separation criteria.
2.0 EVALUATION The current Uninterruptible AC system consists of a single bus powered by either the Uninterruptible AC motor-generator set or an Instrunient AC transformer.
The current Instrument AC system consists of two buses powered by :
- cf the two Instrument AC tr.asformers.
Each of these three buses has an u voltage relay that operates an annunciator in the Control Room to indicate e,ther a degraded bus voltage condition or a loss of power to the buses. Since the buses are powered by 120/240 VAC split-phase power supplies, the present undervoltage relay setpoints, specified in Table 3.2-B of the Technical Specifications, are 8812090169 891207 PDR ADOCK 05000331 P
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220 VAC 5%.
However, with the conversion to 120 VAC single-phase power supplies, it would be necessary to change these setpoints to 110 VAC t5%.
The licensee has also proposed the following administrative changes to the Technical Specifications:
1.
The licensee has proposed to revise the nomenclature used to describe the 125 VDC, 250VDC, 24VDC, Uninterruptible AC and Instrument AC electrical system undervoltage relays in Table 3.2-B of the Technical Specifications.
The change is proposed for consistency and to incorporate standard terminology. Additionally, the licensee has proposed to revise the Trip Level Settings for each of these relays, to specify that the relays actuate on decreasing system voltage, as designed.
2.
Note 6 of the "Notes for Table 3.2-B" currently specifies that the relay drop-out voltage of the Instrument AC and battery bus undervoltage relays, as well as the Trip System Bus Power Monitor relays, will be measured once per operating cycle and the data examined for evidence of relay deterioration. The licensee states that, in the cases of the Instrument AC, Uninterruptible AC, and battery bus undervoltage relays, this require-ment is redundant to the measurement performed annually as part of the calibration specified in Item 14 of Table 4.2-B of the Technical Specifi-cations.
This requirement is not applicable to the System Bus power Monitor relays, which have no undervoltage relay setpoints. According to the bases for 52ction 3.2 of the Technical Specifications, "Surveillance tests other than a monthly functional check of the bus power monitors for RHR, Core Spray, ADS, HPCI, RCIC trip systens are not required since they serve as annunciators for complete loss of power and do not monitor reduction in voltage.
The subject functional check consists of opening the appropriat.e circuit breakers and observing the loss of pow 6r annunciator activation."
The licensee indicates that it was their intent to delete this requirement in a previous license amendment.
However, the requirement appears to have been unintentionally retained in tne Technical Specifications although it contradicts the bases. Therefore, the licensee proposes that the surveil-lance requiren.cnt be removed.
The licensee intends to replace hote 6 by a note stating that there is no trip function associated with the System Bus Power Monitor or undervoltage relays and that the relays provide signals to annunciators only.
3.
The licensee has proposed to revise Item 14 of Table 4.2-B of the Technical Specifications, to include the Uninterruptible AC systen undervoltage relay.
This change is to maintein consistency with the changes in Table 3.2-B.
4 The licensee has propostJ to revise the Bases for Section 3.2 of the Technical Specifications to include the basis for calibration of the Uninterruptible AC system undervoltage relay to provide consistency between Tables 3.2-B and 4.2-B and current testing practices.
In addition, the licensee intends to revise the Bates for Section 3.2 of the Technical Specifications, to allow the removal of appropriate fuses or the opening of appropriate circuit breakers to perform required
3 functional checks of tha undervoltage relays without deenergizing additional electrical loads during testing.
The proposed changes are in conformance with the comitments made to meet the recomendations of R.G.1.97 anc will upgrade power su splies to improve reli-ability. Therefore, the staff finds these changes to:>e acceptable.
3.0 ENVIRONMENTAL CONSIDERATION
S l
This amendment changes a requirement with respect to installation or use of a facility coesonent located within the restricted area as defined h 10 CFR Part 20 or cianger a surveillance requirement. The staff has determined that the amendrent involves no significant increase in the amounts, and no signific:nt 3
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 i
that~che amenda nt involves no significant hazards consideration and there has ben, no public coment on such finding. Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9),
i Pursuantto10CFR51.22(b),noenvironmentalimsactstatementorenvironmental assessment need be prepared in connection with tie issuance of the amendment,
4.0 CONCLUSION
Based on the above evaluation, the staff concludes that the licensee's request to modify the Duane Arnold Energy Center Technical Specifications by revising j
the setpoints of the Uninterruptible AC and Instrument AC undervoltage relays, is in conformance with the comitments made to meet the recomendations of I
Regulatory Guide 1.97, Revision 2.
a The staff has concluded, based on the considerations discussed above, that: (1) l 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 Conunission's regulations, and the issuance of the amendment will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributor:
J. R. Hall Dated: Decanber 7,1988