ML20216J886

Safety Evaluation Supporting Amends 162 & 157 to Licenses DPR-19 & DPR-25,respectively

ML20216J886
Person / Time
Site:	Dresden
Issue date:	09/10/1997
From:	NRC (Affiliation Not Assigned)
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ML20216J876	List: ML20216J872 ML20216J886
References
NUDOCS 9709180138
Download: ML20216J886 (3)

Text

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\\,..... /g WASHINGTON D.C. 30046 4001 SAFETY EVALUATION BY THE OFFICE OF kJCLEAR REACTOR REGULAT103 RELATED TO AMENDMENT NO.162 TO FACILITY OPERATING LICENSE NO. DPR-19 AND AMENDMENT NO.157 TO FACILITY OPERATING LICENSE NO. DPR-25 COMMONWEALTH EDISON COMPANY DRESDEN NUCLEAR POWER STATION. UNITS 2 AND 3 DOCKET NOS. 50-237 AND 50-249 1.0 INTRODUCJJfB By letter dated January 24, 1997. Commonwealth Edison Company (ComEa the licensee), submitted a license amendment to change the Technical Specifications (TS) frequency of the calibration to be performed on the reactor water level instrumentation.

The TS changes have been requested because of the modifications made to the instrumentation during the recent Unit 3 refueling outage. The modifications were performed primarily to improve the reliability of emergency core cooling system (ECCS) initiation on low low reactor water level.

The proposed new TS frequency for calibration of the new level instrumentation is consistent with the ECCS low reactor water level initiation transmitter calibration requirements of NUREG 1433. " Standard Technical Specifications. General Electric Plants. BWR/4" for similar instrumentation.

The same TS change for Unit 2 has been previously reviewed and approved by the NRC staff in Amendment No.145 dated June 28, 1996, in addition minor editorial changes to the TS are being proposed.

2.0 EVALUATION During the recent Dresden Unit 3 refueling outage the licensee modified portions of the ECCS low low water level initiation instrumentation.

The modification was made to improve the reliability of ECCS initiation on low low reactor water level. The existing Yarway level switches which provided the reactor low low water level indication had become prone to instrument drift.

The licensee had found, following several surveillances, that the Yarway level switches calibration had drifted into the nonconservative range. Therefore the licensee chose to replace the existing Yarway level switches with new trip units and trip relays and use the existing Rosemount level transmitter that provides the anticipated transient without scram (ATWS) initiation to also transmit the ECCS low low reactor water level initiation signal.

During the recent Unit 3 refueling outage (May 1997) the four Yarway level switches that provided the initiation signal to the ECCS system on reactor vessel water level low low were removed from the plant.

New trip units and trip relays (one for each Yarway contact pair) were installed and coupled to 9709100138 970910 PDR ADOCK 05000237 P

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. the existing Rosemount level' transmitters that already provided the ATWS trip of the reactor recirculation pumps on reactor water level low low.

The modification was evaluated by the licensee under the provisions of 10 CFR 50.59 and was found not to result in an unreviewed safety question.

In addition, the use of the ATWS signal Rosemount level transmitters does not contradict the diversity requirements of the ATWS rule since the reactor protection system (RPS) scram on low reactor water level has not been affected by this modification. The RPS low reactor vessel water lcvel scram is provided by a different set of sensors and transmitters.

The current frequency for oerforming the calibration of the ECCS Yarway level switches is shown in TS Taale 4.2.B-1 as "0" for quarterly.

This was an appropriate frequency for the Yarway level switches and assured that they would trip within an acceptable range.

The proposed TS would also require calibration of the new trip units to be perf^rmed on a quarterly basis.

The proposed TS would require calibration of the ECCS transmitter associated with the new reactor vessel low low water level trip units and trip relays to be performed every 18 months. The 18-month frequency for calibration of Rosemount transmitters is consistent with the current requirements for the ATWS low low rear, tor water level tri) (Table 4.2.C-1, item 1) and the RPS low reactor-vessel water level scram (Ta ale 4.1.A-1, item 4).

.The proposed TS change is consistent with the calibration requirements fcr the ECCS low low reactor water level initiation transmitter calibration requirements of NUREG 1433.

In addition the staff has reviewed and approved the same TS change for Dresden. Unit 2 as part of Amendment 145 dated June 28, 1996.

Based on the above the staff finds the proposed change to the TS concerning the change in the calibration frequency of the instrumentation associated with the ECCS low low water level initiation is acceptable.

The proposed amendment would make changes to TS Table 4.2.B-1.

The changes are editorial in nature and do not change any requirements of the current TS.

The proposed TS changes would make the nomenclature in Table 4.2.B-1

-consistent with other places in the TS where the distinction between calibration frequencies' for trip units and transmitters is necessary.

For example, for the reactor level reactor scram function listed in Table 4.1.A-1.

Item 4. -the calibration frequency for the transmitter is shown in the table and the trip unit calibration frequency is shown in the associated footnote.

For the ECCS level switches as they are currently hsted in the TS the nomenclature is reversed, i.e., the calibration frequency of the trip unit is listed in the table. The proposed TS would revise the nomenclature for the ECCS low low reactor water level trip unit and transmitter to have the calibration frequency for the transmitter shown in TS Table 4.2.B-1. and the trip unit calibration frequency shown in the associated footnote. The proposed change would make the TS consistent with regards to transmitter and trip unit calibration frequencies and where each is listed throughout the TS.

1 The staff finds the proposed changes acceptable.

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i 3.0: STATE: CONSULTATION-In accordance with the Commission's regulations,.the Illinois State official-was notified of the proposed issuance of the amendments.

The State official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

The amendm nts change a surveillance requirement, The NRC staff has e

determined that the amendments involve 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 amendments-involve no significant hazards consideration, and there has been no public comment on such finding (62 FR 19143). Accordingly, the amendments meet the eligibility criteria:for catgorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b). no environmental im)act statement or environmental assessnent need be prepared in connection wit 1 the issuance of the amendments.

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 issbance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.

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- Principal Contributor: John Stang Date: September 10, 1997 i

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