ML20035G761
| ML20035G761 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/21/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20035G759 | List: |
| References | |
| NUDOCS 9304290283 | |
| Download: ML20035G761 (3) | |
Text
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UNITED STATES O#
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0. 176 TO FACILITY OPERATING LICENSE NO. DPR-32 AND AMENDMENT N0.175 TO FACILITY OPERATING LICENSE NO. DPR-37 (IRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION. UNIT NOS. 1 AND 2 DOCKET NOS. 50-280 AND 50-281
1.0 BACKGROUND
By letter dated October 26, 1992, the Virginia Electric and Power Company, (the licensee), submitted a request for changes to Surry Units 1 and 2 i
Technical Specifications (IS).
The requested changes would (1) revise the TS Intermediate Range (IR) high flux trip setpoint, (2) eliminate any redundant stipulations that predicted critical rod position be above the zero power insertion limit, and (3) change Table 3.7-1, Operator Action 4, to confirm the availability of the Source Range channel, thus ensuring that startup protection is indeed provided by the Source Range channel.
In partial response to the licensee's request, only proposed changes (1) and (3) are addressed in this safety evaluation.
Change (2) will be addressed in a future amendment pending receipt of additional clarification from the licensee.
2.0 EVALUATION 2.1 Increased Intermediate Rance Trio Setooint (TS 2.3.A.I.b)
The Intermediate Range High Flux Power Trip provides backup protection to the Power Range High Flux trip (low set point) during reactor startup. The IR circuitry provides monitoring of the flux level over an eight decade range. A reactor trip is generated based on one out of two channels exceeding a current equivalent of 25 percent rated thermal power. The channels can be manually bypassed when permissive P-10 (2 of 4 power range channels > 10 percent of rated thermal power) is active. Also, the Surry Updated Final Safety Analysis Report (UFSAR) accident analyses do not take credit for this protection. The UFSAR assumes that the reactor trip is provided by either the Source Range or the Power Range High Flux level trips.
The revision of the IR high flux trip setpoint from s 25 percent to s 40 percent power was evaluated by determining the maximum attainable IR trip setpoint, and then evaluating that value for the various startup accidents that could require a backup trip for the Power Range High Flux trip (low i
setpoint).
The IR High Flux trip setpoint will be set nominally at the current equivalent of s 35 percent of rated power.
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2 The licensee evaluated the total channel error for the IR Range High Flux trip by including a statistical combination of the instrumentation and random process measurement uncertainties.
Uncertainties from arithmetic combinations of nonrandom process measurements, control rod insertion effects and the reactor vessel downcomer temperature effects, were treated as biases. The within-cycle power redistribution effects are accounted for by periodic adjustment of the actual plant IR trip setpoint equivalent current.
TS Amendment No. 117 brought the Surry TS in closer agreement with NUREG-0452,
" Standard Technical Specification for Westinghouse Pressurized Water Reactors," Revision 4.
With the technical requirements as specified in this amendment, there is no operating condition in which the IR High Flux level trip provides the sole overpower protection. Consequently, the IR High Flux level trip is needed only to provide backup trip protection, since it is not necessary to assume that this trip function initiates a reactor trip for the UFSAR safety analyses.
The staff agrees with this change.
2.2 Chance to TS Table 3.7-1. Operator action 4.
The revision to Operator Action 4 of TS Table 3.7-1 provides an allowed outage time for conditions below a power level of P-6 with one IR channel inoperable.
This revision establishes an allowed outage time for the Source Range Channel when the power level is below P-6.
The revised technical specification, action 4, when combined with the other Source Range requirements for power above P-6 in Table 3.7-1, yields the same requirements as those for Operator Action 13 in NUREG-0452, Revision 4.
The current Surry TS do not limit the duration for which one source range channel can be inoperable at a thermal power level below P-6.
Thus, this will provide startup protection by providing confirmation of the availability of the source range channel.
The staff agrees with this change.
3.0
SUMMARY
The staff has reviewed the licensee's proposed TS changes to the Intermediate Range High Flux trip setpoint, and the change to Table 3.7-1.
Based on this review, we conclude that the proposed changes satisfy staff positions and requirements in these areas. Operation subject to these TS changes is acceptable, r
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendments. The State official had no comment.
5.0 ENVIRONMENTAL CONSIDERATION
r These amendments change a requirement with respect to 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 amendments involve no
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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 these amendments involve no significant hazards consideration and there has been no public comment on such finding (57 FR 61122).
Accordingly, these amendinents meet the eligibility criteria for categorical exclusion set forth in 10 CFR Sl.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 these amendments.
6.0 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 these amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: T. Attard Date: April 21, 1993