ML20077A586
| ML20077A586 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 11/18/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20077A585 | List: |
| References | |
| NUDOCS 9411250061 | |
| Download: ML20077A586 (3) | |
Text
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UNITED STATES g
g NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20S554001 o
49.....,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 204 TO FACILITY OPERATING LICENSE NO. DPR-49 IES UTILITIES INC.
CENTRAL IOWA POWER COOPERATIVE CORN BELT POWER COOPERATIVE DUANE ARNOLD ENERGY CENTER DOCKET NO. 50-331
1.0 INTRODUCTION
The proposed amendment requests revision to the Surveillance Requirements (SR) for certain Rod Block Instrument systems.
Specifically, the requirement to perform Channel Functional Tests prior to STARTUP for the Rod Block Monitor (RBM), Flow-biased Average Power Range Monitor (APRM) and Recirculation Flow instruments is being revised to allow the SRs to be performed after the reactor is in the Run mode, but prior to when the plant safety analysis assumes each system is to function.
Performance of the SRs " prior to STARTUP" requires the extensive use of jumpers and relay blocks.
The proposed changes in the SRs ensure that the function will be demonstrated to be OPERABLE prior to when they are required to be OPERABLE, but without the need for the,iumpers and relay blocks.
2.0 EVALUATION for the RBM system, the proposed change to the SR frequency merely revises the requirement to match the existing mode requirement for OPERABILITY in TS Table 3.2-C.
As OPERABILITY will be demonstrated prior to entering the operating condition where the system is required to be OPERABLE, the proposed revision to the SR frequency is found to be acceptable by the staff.
The proposed change to the SR frequency for the APRM Flow-Biased Rod Block Channel Functional Test to allow the SR to be performed after the reactor enters the RUN mode, but prior to exceeding 25% rated thermal power, will ensure that the system is demonstrated to be operable prior to reaching a power level where the Safety Limit Minimum Critical Power Ratio (SLMCPR) could be challenged.
Extensive use of jumpers and relay blocks will be avoided by i
performing the SR in the RUN mode, thus eliminating the potential for either the inadvertent actuation or disabling of an Engineered Safety feature (ESF).
During the performance of this SR, the reactor mode switch is placed in the l
RUN position, although the plant is actually in a Cold Shutdown condition.
In order to preclude ESF actuations that are not germane to this Channel I
9411250061 941118 PDR ADOCK 05000331 p
Functional Test, jumpers and relay blocks are used in those logic trains.
Although the probability is small, the potential does exist for either a jumper or relay block to become dislodged during the test, allowing an inadvertent ESF actuation, or a failure to remove the jumper or relay block at the completion of the SR could occur, thereby disabling the ESF logic until its next scheduled SR is performed. Therefore, the proposed change will enhance safety by eliminating the use of these jumpers and relay blocks.
Consequently, the staff finds that the proposed change to the APRM Flow-biased Rod Block SR is acceptable.
The proposed change in the SR frequency for the Recirculation system rod blocks is the same as those proposed for the APRM system.
As the sole purpose of the Recirculation system rod blocks is to ensure that an invalid signal for reactor recirculation flow is not input into the flow-biased APRM rod block circuits, validation of the OPERABILITY of these rod blocks prior to exceeding 25% rated thermal power is not critical, based upon the justification given above that the APRM system rod blocks themselves are not critical below 25%
rated thermal power. Consequently, the staff finds that the proposed changes in the SR frequency for the Recirculation Flow Rod Blocks are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Iowa State official was notified of the proposed issuance of the amendment.
The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
S This amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and changes surveillance requirements. The staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluent that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration and there has been no public comment on such finding (59 FR 45025). Accordingly, the 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 the amendment.
5.0 CONCLUSION
The staff has 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, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
J. Sebrosky Date: November 18, 1994
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