ML20213G916
| ML20213G916 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 05/13/1987 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20213G907 | List: |
| References | |
| NUDOCS 8705190027 | |
| Download: ML20213G916 (5) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION o
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SAFETY EVALUATICN BY THE OFFICE OF NUCLEAR REACTOR REGt!LATION RELATED TO AMENDMENT NO.
105 TO FACILITY OPERATING LICENSE NO. DPR-3 YANKEE ATOMIC ELECTRIC COMPANY YANKEE NUCLEAR POWER STATION DOCKET NO.50-029
1.0 INTRODUCTION
By letter dated October 9,1986, Yankee Atomic Electric Company (the licensee) submitted Proposed Change (PC) No. 201 to Operating License No. DPR-3 requesting that Technical Specifications (TS) Table 4.3-1, Reactor Protective System Instrumentation Surveillance Reouirements, be amended to revise the Channel Calibration Surveillance Interval and Channel Functional Test for the Power Range and Intermediate Power Range Neutron Flux Channels (Functional Unit #2).
2.0 DISCUSSION Six channels of nuclear instrumentation at Yankee provide inputs to the reactor protection system for reactor trip on flux level. The high neutron flux level trip is set at 108% for power operations and is nanually set to the low power sett:'ng of 35% power when reactor power is less than 15 MWe. Channels No. 3, 4, and !. are the intermediate power range (IRPR) channels and channels No. 6, 7, and 8 are the power range channels (PR). The low power scram operates on channels No. 6, 7, and 8 only. When both the PR and IRPR switches are in the
" coincidence" pcsition (the normal position) a scram will result if two out of six channels reach the scran setpoint. With the low power scram set relay in service and the PR switch in " coincidence", a scram will result when two out of the three channels reach the low power trip setpoint.
In order to test the low power scram setpoint, the low power scram set relay switch must be in the low power set position. During power operation, when above the low power setpoint, a scram would result when the switch was repositioned because three channels (one more than required) would then be above the trip setpoint.
The existing TS specify the channel calibration of the six channels be performed quarterly and that channel functional tests be perfonned monthly.
Channel calibration and channel functional tests are defined in the Yankee TS as follows:
8705190027 870513 PDR ADOCK 05000029 p
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j CHANNEL CALIBRATION 1.9 A CHANNEL CALIBRATION shall be the adjustment, as necessary, of the channel output such that it responds with the necessary range and accuracy to known values of the parameter which the channel monitors. The CHANNEL CALIBRATION shall encompass the entira channel including the alam and/or trip functions, and shall include the CHANNEL FUNCTIONAL TEST. The CHANNEL CALIBRATION may be performed by any series of sequentia!. cved&ppi;.g 0. total channel steps such that the entire channel is calibrated.
CHANNEL FUNCTIONAL TEST 1.11 A CHANNEL FUNCTIONAL TEST shall be the injection of a simulated signal j
into the channel as close to the primary sensor as practicable to verify OPERABILITY including alam and/or trip functions.
Proposed Changes The licensee proposed to modify the Technical Specification (TS) as follows:
On Table 4.3-1, change the Functional Unit, ib. 2, Power Range, Neutron Flux and Intermediate Power Pange, Neutron Flux, Channel Calibration from a Quarterly to Refueling interval; and add Note (6), Low trip setpoint verification excluded, to the Channel Functional test requirement.
The licensee stated that "this delineation and clarification is necessary 3
because the original plant circuity design does not permit surveillance of the low power setpoint circuitry at power without a resulting reactor trip. This surveillance has been, and nomally is, perfomed at refueling interval."
The above change is the result of an evaluation of an event described in Licensee Event Report (LER) 50-29/85-07. This LER described a situation where the low trip set point of Nuclear instrumentation power range channels 7 and 8 i
were found to exceed Technical Specification limits. As a result of this problem, the licensee reviewed the TS and noted that a change was necessary since functional testing for the low scram set trip will cause a reactor scram if the plant is greater than 15 MWe.
e Review Criteria / Requirements NUREG-0452, Standard Technical Specifications for Westinghouse Pressurized Water Reactors, Revision 4, was used as the applicable review criteria for these TS.
3.0 EVALUATION During NRC Inspection 50-29/87-02, a staff inspector reviewed licensee surveillance test procedures and instrument drawings. As a result of this inspection the staff verified that the existing plant circuity for the nuclear instramentation system does not permit surveillance of the low power trip setpoint while at power without initiating a reactor trip. The staff also verified that the proposed Technical Specification (TS) change does not alter the Safety Analysis for the Yankee Nuclear Power Station (YNPS) since no credit is taken for the low setpoint function in the accident analysis.
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The current YNPS practice is to perfom all elements of a nuclear instrument calibration during the monthly channel. functional test, except for the t
calibration or test of the low trip set point which cannot be done at power.
This current practice by the licensee is more conservative than the current monthly channel functional test required by the TS in that it incorporates all elements of the functional test to verify channel operability and in addition, perfoms a channel calibration.
Except for the low trip setpoint, the monthly test exceeds the current TS requirement to perfom a quarterly channel calibration. During inspection 50-29/87-02, the staff reviewed _ test t
procedures and test data, and verified that the channel functional test and the channel calibration as currently perfomed at YNPS provide assurance of channel c*rability that is equivalent in scope to channel fun::tional test and calibrations specified by the Westinghouse Standard Technical Specification (STS) except for testing the low trip setpoint.
Under the proposed change, channel calibration is required for these flux channels (including the high power setpoint) at refueling intervals.
As noted above, the monthly functional test perfoms many of the elements of a calibration.
Therefore, the staff concluded that in order to clarify the proposed TS change, the following addition should be incorporated into Note (6) of Table 4.3-1:
a "The channel Functional Test, perfomed on a monthly basis, provides all the elements of a calibration that can be done at power" j
The addition of this note is consistent with current plant practice, and assures that the YNPS TS and the STS will be consistent in the requirements for calibration of the power range and intermediate range nuclear instrumentation channels.
Further, the above note recognizes that the channel functional test is accomplished by a channel calibration and assures conformance to the STS. This change is considered to be a clarification of i
the intent of the TS change and to be within the scope of the Notice of i
Consideration that was published in the Federal Register on November 19, 1986 (51 FR 41872). This change was discussed with and agreed to by the licensee.
Based on the above evaluation, the staff finds the proposed TS changes, as modified, to be acceptable.
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4.0 ENVIRONMENTAL CONSIDERATION
This amendment involves a change in the installation or use of a facility compoi located within the restricted area as defined in 10 CFR Part 20.
The s<
is determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that l
may be released offsite, and that there is no significant increase in i
individual or cumulative occupational radiation exposure. The Connission has previously issued a proposed finding that this amendment involves no significant hazards consideration and there has been no public comment on such i
findings. Accordingly, this amendment meets the eligibility criteria for
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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.
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5.0 CONCLUSION
The staff has concluded, based on the considerations discussed above, and with the incorporation of the aforementioned addition to Note 6 of Table 4.3-1 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 this amendment will not be inimical to the common defense and security or to the health and safety of the public.
6.0 PRINCIPAL CONTRIBUTOR David T. Wallace, Region I Dated: ggy 13 YE7
k'AMENDMENTNO.
105 TO FACILITY OPERATING LICENSE N0. DPR YANKEE-R0WE NUCLEAR POWER STA, l
DISTRIBUTION:
y DOCKET File 029 i
NRC PDR LPDR ELJordan BGrimes JPartlow EBut.cher itktanom OPA Wanda Jones RDiggs, LFMB PD I-3 Reading OGC-Beth ACRS (10)
M. Rushbrook - 5 Project Manager - EMcKenna(2)
TBarnhart(4)
DHagen SVarga BBoger CMiles, PA DHaverkamp, Region I Region I - 4
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