ML20211B393
| ML20211B393 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 05/30/1986 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20211B391 | List: |
| References | |
| NUDOCS 8606110628 | |
| Download: ML20211B393 (5) | |
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UNITED STATES 3
NUCLEAR REGULATORY COMMISSION O
j WASHINGTON, D. C. 20555 k..... /
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMEN 0 MENT N0. 5 TO FACILITY OPERATING LICENSE N0. NPF-38 LOUISIANA POWER AND LIGHT COMPANY WATERFORD STEAM ELECTRIC STATION, UNIT 3 DOCKET NO. 50-382
1.0 INTRODUCTION
By letter dated December 2, 1985, as supplemented by letter dated April 3, 1986, Louisiana Power and Light Company (the licensee), requested changes to the Technical Specifications (Appendix A to Facility Operating License NPF-38) for the Waterford Steam Electric Station, Unit 3.
The proposed changes would:
(1) delete the Core Protection Calculator (CPC) Type I and Type II addressable constants; (2) incorporate the results of the Waterford Core Operating Limit Supervising System (COLSS) out-of-service analysis; (3) revise the requirements for low temperature overpressure protection (LTOP) to allow hydrostatic tests in Mode 4; and (4) allow the measurement of moderator temperature coefficient (MTC) following each refueling outage to be taken at any power level greater than 15% prior to reaching 40 effective full-power days (EFPD) core burnup rather than within 7 EFPD of reaching 40 EFPD core burnup.
2.0 DISCUSSION The changes to the technical specifications requested by the licensee are in four areas as described below.
Core Protection Calculator Addressable Constants The proposed change removes the Type I and Type II Core Protection Calculator addressable constants from the Technical Specifications.
The proposed change deletes Technical Specification 2.2.2, " Core Protection Calculator Addressable Constants"; deletes Table 2.2-2, which provided a listing of the CPC Type I and Type II addressable constants; and deletes Bases 2.2.2.
The proposed change also revises the appropriate page of the Index, deletes the reference to Specification 2.2.2 from Notation (9) of Table 3.4-1 and deletes the Note in Administrative Control 6.8.1.g.
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, Core Operating Limits Supervisory System The proposed change modifies the Technical Specifications to incorporate the results of the Waterford 3 COLSS out-of-service analysis. The change revises Technical Specifications 3.2.1, " Linear Heat Rate", 3.2.4, "DNBR Margin", 3.2.7, " Axial Shape Index", and the associated Bases. The change also adds Figure 3.2-la " Allowable Peak Linear Heat Rate vs Tc for COLSS Out-of-Service"; deletes Figures 3.2-2 "DNBR Margin Operating Limit Based on COLSS" and replaces it with "DNBR Margin Operating Limit Based on CPC's (COLSS Out-of-Service, CEACs Operable)"; revises Figures 3.2-3 "DNBR Margin Operating Limit Based on CPC's (COLSS Out-of-Service, CEACs Inoperable)";
and revises Action 6.b.1 of Table 3.3-1.
Low Temperature Overpressure Protection The proposed change revises the applicability of Technical Specification 3.4.8.3, " Overpressure Protection System", in Mode 4 to allow a lower reactor coolant system temperature during inservice leak and hydrostatic testing without imposing the requirements of low temperature overpressure protection.
Moderator Temperature Coefficient The proposed change modifies Surveillance Requirement 4.1.1.3.2 of Technical Specification 3.1.1.3, Moderator Temperature Coefficient. The Requirement specifies the required MTC measurement frequency, including the requirement that MTC be measured within 7 effective full power days (EFPD) of reaching 40 EFPD core burnup. The proposed change allows this measurement to be taken at a thermal power level greater than 15% at any time prior to reaching 40 EFPD core burnup, 3.0 EVALUATION i
Core Protection Calculator Addressable Constants As a method to avoid gross errors in operator entry of an addressable constant, the Core Protection Calculators (CPC) software was designed with automatic acceptable input checks against range limits that are specified by the CPC functional design requirements.
In addition, CPC surveillance l
requirements (Table 4.3-1) require that the monthly channel functional test shall include verification that the correct values of addressable constants are installed in each operable CPC. Modifications to the addressable constants are accomplished through strict administrative procedures as required by Technical Specification 6.8.1(g).
CPC software changes involving additions or deletions to addressable constants as well as changes to software limit values are made and tested under NRC-approved software change procedures.
l Based on these requirements, and on the fact that the NRC has previously I
approved the deletion of CPC addressable constants from the Palo Verde l
Unit 2, San Onofre Unit 2 and 3, and Arkansas Unit 2 Technical Specifications,
. the staff finds the proposed removal of the addressable constants and related administrative requirements from the Waterford 3 Technical Specifications acceptable provided that the following alternative measures are adopted:
(1) sufficient margin is maintained in CPC constants, such as azimuthal tilt allowance, to preclude excessive operator interaction with the CPCs during reactor operation, and (2) no CPC software changes involving additions or deletions to addressable constants or changes to software limit values are made without prior approval of NRC.
Core Operating Limit Supervisory System The Core Operating Limit Supervisory System (COLSS) is normally used to monitor linear heat rate, DNBR margin, and axial shape index.
- However, whenever COLSS is out of service, the CPCs are used to perform the safe monitoring function. Since the CPCs use excore neutron detectors and are required to provide protection during certain transients and accidents, the CPC uncertainties and margins are more limiting than those of COLSS, which uses incore neutron detectors. These extra conservatisms built into CPC for transient protection are not all required when the CPCs are being used for monitoring. The licensee has credited these conservatisms in the COLSS Out-of-Service limits of Technical Specifications 3.2.1, 3.2.4, and 3.2.7 when the CPC is being used for monitoring. These conservatisms provide approximately 10% LHR and 12% DNBR power margin credits which have been translated into COLSS Out-of-Service LC0 adjustments in the proposed Technical Specification changes. Since these conservatisms are not taken from the CPCs but rather are credited in the COLSS Out-of-Service limits of the Technical Specifications, the CPC transient protection is not affected. However, these credits will have to be re-evaluated when the CPC changes associated with the CPC Improvement Program (CIP) described in CEN-308-P, "CPC/CEAC Software Modifications to the CPC Improvement Program" are implemented at Waterford Unit 3, since some CPC penalties were reduced as a part of the CIP. Therefore, the staff concludes that the licensee's proposal to take credit for the conservatisms built into the CPSs when they are being used in a monitoring function, is acceptable.
Low Temperature Overpressure Protection i
Technical Specification 3.4.8.3 defines the requirements for low temperature j
overpressure protection (LTOP) provided by the shutdown cooling system (SCS) l relief valves and the applicable modes of plant operation.
The current l
restriction in 3.4.8.3 requires that LTOP be implemented during Mode 4 when the temperature of any reactor coolant (RCS) cold leg is less than 285'F.
l Also, Action Statement (a) of Technical Specification 3.4.9 requires that in
(
the event that a code Class 1 component does not meet the integrity requirements of 3.4.9 (e.g., a weld repair), the structural integrity of the affected l
l
1.
component must be restored prior to increasing the RCS temperature higher than 272*F (70 F above the minimum temperature required by NDT considerations, presently 202 F per Figure 3.4-2).
With the SCS connected to the RCS, a hydrostatic test of the RCS, as required by the ASME code could be performed since the SCS relief valves would lift. The licensee's proposed change of Technical Specification 3.4.8.3 revises the applicability in Mode 4 to allow a lower RCS temperature of 260 F without LTOP to enable conducting the RCS hydrostatic test.
Currently, Technical Specification 3.4.8.3 contains no provision for conducting the RCS hydrostatic test after a refueling outage.
This provision is included in other plant Technical Specifications and the staff concludes that its omission from the Waterford 3 Technical Specifications was not due to any plant specific technical concerns but was due to an oversight.
Since the proposed change results in a minor and necessary relaxation of the LTOP implementation temperature specification, and is consistent with the existing Appendix G curve (Figure 3.4-2) as well as with other plant Technical Specifications, the proposed change is acceptable. However, to eliminate future changes to the technical specifications on temperature limitation for hydrostatic testing of the RCS due to future changes of Figure 3.4-2, the staff concludes that the note added to the applicability for Technical Specification 3.4.8.3 should be modified as follows:
"During inservice leak and hydrostatic testing, use the temperature limitation indicated by the curve for inservice test on Figure 3.4-2, with Reactor Coolant System heatup rate restricted in accordance with Specification 3.4.8.1.g.
Moderator Temperature Coefficient The limitation on Moderator Temperature Coefficient (MTC) specified in Technical Specification 3.1.1.3 is provided to ensure that the assumptions used in the accident and transient analyses remain valid throughout the fuel cycle. The MTC varies slowly as a function of core burnup, due principally to the reduction in reactor coolant system boron concentration with fuel burnup.
It is most positive at the beginning of core life and becomes more negative with increasing burnup. The surveillance requirements for measurement of the MTC are intended to provide confirmation that the measured value is within its Technical Specification limit, thereby assuring that the calculational technique for calculating the MTC is valid. The proposed change does not alter the LC0 criteria, nor is the measured MTC value used as input to any safety-related calculation.
In addition, all standard criteria (e.g. xenon equilibrium) will be met when performing the MTC measurement during startup physics test to ensure an accurate measurement. Therefore, the proposed change allowing for an MTC measurement earlier in the core cycle has no effect on the existing safety margin and is acceptable.
1 i
, 4.0 CONTACT WITH STATE OFFICIAL The NRC staff has advised the Administrator, Nuclear Energy Division, Department of Environmental Quality, State of Louisiana of the proposed determination of no significant hazards consideration. No comments were received.
5.0 ENVIRONMENTAL CONSIDERATION
This amendment involves changes in the installation or use of facility components located within the restricted area. The staff has determined that the amendment involves no significant increase in the amounts of any effluents that may be released offsite and that there is no significant increase in individual or cumulative occupation radiation exposure. The Commission has previously issued proposed findings that the amendment involves no significant hazards consideration, and there has been no public comment on such findings. 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 envirorimental assessment need be prepared in connection with the issuance of this amendment.
6.0 CONCLUSION
Based upon our evaluation of the proposed changes to the Waterford 3 Technical Specifications, we have concluded that:
there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and such activities will be conducted in compliance with the Commission's regulations and the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
We, therefore, conclude that the proposed changes are acceptable, and are hereby incorporated into the Waterford 3 Technical Specifications.
Dated: May 30, 1986 G
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