ML17278A567
| ML17278A567 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 01/07/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17278A566 | List: |
| References | |
| TAC-59904, NUDOCS 8601160223 | |
| Download: ML17278A567 (7) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION
'ASHINGTON, D. C. 20555 SAFETY EVALUATION AMENDMENT NO.
20 TO NPF-21 WPPSS NUCLEAR PROJECT N0.2 DOCKET NO. 50-397 INTRODUCTION By letter dated October 17, 1985, the Supply System requested an amendment to the WNP-2 Technical Specifications on an emergency basis.
The requested amendment would change the Limiting Condition of Operation, 3.3.7.7 to permit LPRM calibration in some instances with fewer than five operable Traversing In-core Probe (TIP) detector channels.
EVALUATION The Local Power Range Monitors (LPRMs) provide information to the process computer to permit the determination of the core power distribution.
They also provide information to the Average Power Range Monitor (APRM) channels to permit the determination of core power.
The combination of core power distribution and core power permit the monitoring of core thermal limits (MAPLHGR, LHGR, MCPR).
In order to perform these functions the LPRMs must be intercalibrated (i.e. adjusted to yield the same output signal for a given input signal (flux value).
This intercalibration is performed. by the Traversing In-core Probe (TIP) system.
In WNP-2 there are five TIP system channels, each of which provides access to a number of LPRM strings and all of which provide access to a single (control) string.
When all five TIP channels are operable, every LPRM in the core may be calibrated.
When a TIP channel is not operable a certain number of LPRM strings cannot be directly calibrated.
However, indirect calibration of an unaccessed string may be performed if a symmetric string can be accessed by another TIP channel provided the core power distribution is symetrical.
The proposed Technical Specification change restricts the use of indirect calibra-tion to a symmetric rod pattern and the total core TIP asyIImetry is limited to assure a symmetric power distribution.
We conclude that the proposed Technical Specification change is acceptable and that the TIP system with one channel inoperable may be used to fulfil the requirements of Specification 3.3.7.7.
We further conclude that the data obtained by calibration performed September 1985, constitutes acceptable data to satisfy the surveillance requirements of Section 4.3.7.7.
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FINAL NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION A proposed amendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not (I) involve a significant increase in the probability or consequences of an accident previously evaluated; (2) create the possibility of a new or different kind of accident from an accident previously evaluated; or (3) involve a significant reduction in a margin of safety.
The Supply System has evaluated this request per 10 CFR 50.92 and determined that it does not involve a significant hazards consideration because it does not:
( 1)
Involve a significant increase in the probability or consequences of an accident previously evaluated, because the calibration of LPRMs using symmetric string base distributions provide LPRM data within the normal uncertainty expected for calibrations with all five machines operable.
Consequently, this condition will not adversely affect core thermal limit calculations and thus the probability or consequences of an accident, as previously evaluated, are not changed.
(2)
Create the possibility of a new or different kind of accident than previously evaluated, because margins to safety limits, are not affected.
(3)
Involve a significant reduction in a margin of safety, because calibration of inaccessible LPRM strings using symmetric string base flux distribution data from symmetric strinqs that are accessible by an operable TIP machine is within the normal uncertainty limits obtained with five TIP machines operable.
Based on its review, the staff concurs in the determinations made by the licensee.
BASIS FOR EMERGENCY SITUATION As originally issued, the Technical Specifications stated that the TIP system shall be operable with five detectors when calibrating the LPRM detectors.
One of the TIP system channels is inoperable and Supply System personnel approached the NRC staff (Region V and NRR offices on September 4, and September 5,
1985) with a proposal to allow calibration of LPRMs in the inaccessible strinqs by the use of base distributions in symmetric strings which are-accessible by one of the remaining four operable TIP machines.
(With the reactor core operating with a symnetrical control rod pattern, symmetry exists between strings which are inaccessible and those which are accessible by an operable TIP machine.)
Ad Hoc approval was provided by both NRR and Region V.
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The administrative process in obtaining this approval has drawn questions and has resulted in the need to change the subiect Technical Specifications to reflect the ability to calibrate using the above methodology.
Absent approval of this change on an emergency basis, WNP-2 would be required to operate below 25K power until the inoperable probe is returned to service.
Below 25% power reliance on the LPRM calibration is not required.
The Supply System did not foresee the informal approval of the calibration methodology being questioned and was proceeding to process a technical specification amendment change under the normal process.
It was not until questions arose on the informal, approvals that it became evident that an emergency technical specification change was necessary.
The Supply System therefore could not reasonably have submitted its request earlier.
It is the Supply System's intention to return the inoperable TIP to service at the most opportune time.
Present conditions in the Pacific Northwest require WNP-2 to remain at power.
The inoperable probe will be repaired at the next planned or forced outage or prior to changing to an asy~etric control rod pattern.
ENVIRONMENTAL CONSIDERATION This amendment involves a change to the requirement with respect to the installation or use of a facility component located within the restricted area as definded in 10 CFR Part 20.
The staff has determined that the amendment involves 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 Commission has determined that this amendment involves no significant hazards consideration.
Accordingly, this amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR Section 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.
CONCLUSION Consulation with th6 State of Washington was conducted by telephone on December 26, 1985.
The State of Washington had received the Supply System's request for amendments, had reviewed it and has no comment.
We have concluded, based on the considerations discussed above, that:
(I) 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 co@non defense and security or to the health and safety of the public.
'Principal Contributors:
Dated:
JAN 0 2'86 Walter L. Brooks John 0. Bradfute
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Issuance of Amendment No.
20 to Facilit 0 eratin License No. NPF-21 WPPSS Nuc ear ro'ect No.
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