ML17289A691
| ML17289A691 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 06/26/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17289A690 | List: |
| References | |
| NUDOCS 9207060125 | |
| Download: ML17289A691 (4) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555 9207060125 920626 PDR ADOCK 05000397 P
PDR SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 108 TO FACILITY OPERATING LICENSE NO.
NPF-21 WASHINGTON PUBLIC POWER SUPPLY SYSTEM NUCLEAR PROJECT NO.
2 DOCKET NO. 50-397
1.0 INTRODUCTION
By letter dated November 18,
- 1991, Washington Public Power Supply System submitted a request for changes to the Technical Specifications (TS) for Nuclear Project No. 2.
The proposed changes would delete the reference to footnote (e) associated with TS Table 3.3.6-1, "Control Rod Block Instrumentation,"
item 4.a.
This would remove an error that resulted from an oversight in the original preparation of the WNP-2 TS and allow TS to conform to actual plant design with respect to the control rod block signals associated with the intermediate range monitoring (IRM) system.
2.0 EVALUATION The IRHs provide an indication of neutron flux, and thus reactor power level, during reactor startup and shutdown operations.
It also provides reactor trip and control rod block signals if abnormal flux conditions occur, the system malfunctions, or the detectors are not properly positioned in the core.
The IRHs are fully inserted during reactor startup and plant heatup operation.
The IRHs are withdrawn from the core when the power level exceeds the range of the instruments.
This is done to prolong the life of the detectors by not exposing them to the higher neutron flux.
During conditions when the IRHs are required, if they were not in the "full in" position, the indicated power may actually be less than the actual power level in the core.
Thus any trip or rod block signals would occur at an actual higher power level then intended by design.
Therefore, a "detector not full in" rod block signal, though it is not a safety-related signal, is provided to ensure rods cannot be withdrawn when the IRM detectors are not in their optimum position with the reactor at a low power level.
Footnote (e), affiliated with item 4.a of TS Table 3.3.6-1, indicates that the "detector not full in" signal is bypassed whenever the IRHs are in the "range 1" setting (which is the lowest setting of the 10 possible range settings related to the IRHs).
Such a bypass would disable the rod block function while the IRMs were at their lowest range setting.
If the IRHs were not fully inserted, rods could be withdrawn with a lower than actual indication of
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power.
Therefore, while in range 1, the IRHs would not be able to satisfy the intent of this rod block function.
The licensee states that this bypass signal was not part of the original design of the system, was never considered, and does not exist.
Design documents confirm that the IRM Range Selector Switch is not physically in the circuitry for the "detector not full in" rod block signal.
Bypassing the IRH control rod block signal in range 1 would not be conservative.
While in range 1, overlap with the source range monitors (SRHs) is confirmed and this is used to verify that the IRHs are operating properly.
The licensee has proposed a change to TS Table 3.3.6-1 that changes the TS to show the original and current intent of the design of the IRH system.
The NRC has reviewed this matter and finds the proposed changes to the TS for WNP-2 are acceptable.
3.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Washington State official was notified of the proposed issuance of the amendment.
The State official had no comments.
- 4. 0 ENVIRONMENTAL CONSIDERATION The amendment changes a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC 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 previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (57 FR 22272).
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 Commission 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:
William H.
Dean Date:
3une 26, 1992
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