ML20057A355

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Safety Evaluation Supporting Amend 163 to License DPR-61
ML20057A355
Person / Time
Site: Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date: 09/02/1993
From:
Office of Nuclear Reactor Regulation
To:
Shared Package
ML20057A352 List:
References
NUDOCS 9309140064
Download: ML20057A355 (4)


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wAssiwoton, o.c. 2osswooi SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT N0.163 TO FACILITY OPERATING LICENSE NO. DPR-61 CONNECTICUT YANKEE ATOMIC POWER COMPANY l

HADDAM NECK PLANT l

DOCKET NO. 50-213 l

i l.0 INTRODUCTION By letter dated May 18, 1993, the Connecticut Yankee Atomic Power Company (the licensee) submitted a request for changes to the Haddam Neck Plant Technical Specifications (TS). The requested change would add a footnote to TS Section 3.4.2.2, " Reactor Coolant System - Operating," to allow a relaxation in the pressurizer safety valve setpoint tolerances to +3% from +1%.

This +3%

i tolerances is used for the "as found" acceptance criteria for additional valve l

testing.

2.0 EVALUATION The Haddam Neck Plant overpressure design incorporates three Code safety l

valves on the primary system pressurizer. The three Code safety valves are spring operated, and automatically open at set pressures of 2485, 2535, and 2585 psig respectively to prevent exceeding the reactor coolant system (RCS) pressure safety limit of 2735. The proposed change would allow relaxation of the pressurizer safety valve (PSV) setpoint tolerance from +1% to +3%.

The licensee proposes to use the +3% tolerance for the "as-found" acceptance criteria for additional valve testing required by ASME Section XI, Article i

IWV-3513. The proposed 15 changes will not change the "as-found" lower bound of -l% or the "as-left" tolerance requirements of 1% of their nominal l

setpoints following testing if the test exceeds the tolerance of 1%. An ASME l

Code,Section III requirement for the PSVs is that they be designed to open l

within 1% of the set pressure. The current TS Limiting Condition for Operation (LCO) also imposes the tolerance of i1% on their set pressure.

Currently the TS surveillance requirements for the PSVs requires that testing be performed in accordance with Section XI of the ASME Boiler and Pressure '

Vessel Code and applicable addenda, as required by 10 CFR 50.55a(g). The surveillance requirements indicate that the PSVs should be tested to verify i

that their lift pressure and seat leakages are acceptable pursuant to the Haddam Neck Plant Inservice Testing (IST) program which complies with the ASME Boiler and Pressure Vessel Code,Section XI, 1983 Edition, through the Summer 1983 Addenda. This document does not indicate the tolerance to be applied to 9309140064 930902 PDR ADDCK 05000213 P

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i i the safety valve lift pressure verification. The licensee uses the 1%

indicated in the LCO as the acceptance criteria for the PSVs during ASME Section XI testing. Under the current testing requirements, when a PSV has a tested lift pressure outside the 1% tolerance specified in the LCO, it must be repaired or replaced per IWV-3514 and additional valves in the system be tested per IWV-3513.

The 1989 Edition of the ASME Code,Section XI, now requires that the PSVs be tested pursuant to the ASME/ ANSI OM-1987, Part 1, " Requirements for Inservice Performance Testing of Nuclear Power Plant Pressure Relief Devices." This i

allows the tested lift pressure to exceed the stamped set pressure by up to 3%

before declaring a test failure.

It also includes guidelines for testing j

additional valves when a valve exceeds the 3% tolerance. CYAPC0 will only use the upper +3% tolerance for the "as-found" acceptance criteria for additional valve testing required by ASME Section XI, Subsection IWV-3513.

The proposed TS will still require that the PSV setpoints be restored to within 1% of their nominal setpoints following testing. Therefore, the proposed relaxation of the setpoint tolerance has been determined to be in compliance with the 1989 edition of the Code which has been endorsed by the i

staff.

l The Haddam Neck Plant's pressurizer design is governed by ASME Code Section VIII. For a vessel with multiple safety valves, the Code requires that:

a.

At least one safety valve shall be set to open at design pressure. Additional relief valves, if any, shall be set to open at no greater than 105 percent of the design 1

pressure (UG-133a);

b.

Total pressure relief capacity shall be sufficient to prevent the system pressure to rise no more than 10 percent above the system design pressure (UG-125c) and Code Case 1271N(1).

The above Code requirements stipulate that:

1.

One safety valve has to be set at the system design pressure which is 2485 psig. The lowest setpoint for the Haddam Neck Plant PSVs is 2485 psig.

Therefore, the Code requirement is met.

2.

The highest relief valve setpoint pressure including tolerance shall be no greater than 105 percent of design (2625 psia). The highest setpoint is 2600 psia which is within the above limit of 2625 psia and therefore, this Code requirement is met.

3.

Safety analysis with the new setpoint tolerances must be performed to show that the RCS pressure remains below 110 percent of the design pressure (2750 psia) for the

. i most limiting overpressurization event. The impact of the increase in the upper bound of the pressurizer safety valve setpoints has been evaluated for LOCA and non-LOCA transients.

Since the PSVs are not challenged in a LOCA, the change of the PSVs setpoints has no impact on the design basis LOCA analysis.

Further, since DNBR increases as RCS pressure increases, increasing the upper bound of the PSV setpoint is bounded by the current analysis. The only impact of increasing the upper bound on PSV setpoints

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is a slight increase in the predicted maximum RCS pressure for overpressure events. The Loss of Load event is the limiting design basis overpressure event and will remain the limiting design basis overpressure event with the proposed setpoint tolerance change. The Loss of Load event was reanalyzed assuming a +3% setpoint drift with 3%

accumulation on all three pressurizer safety valves.

The l

analysis predicted a maximum pressurizer pressure of 2690 psia which is within the acceptance criterion of 2750 psia.

The staff has reviewed the licensee's evaluation on the impacts of the proposed TS changes to allow a relaxation in the PSV setpoint tolerance to +3%

for testing acceptance criteria. The staff has concluded that the change meets the applicable Code requirements and therefore, the staff finds the TS i

change acceptable.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the Connecticut state official was notified of the proposed issuance of the amendment. The state official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

I The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area is defined in 10 CFR Part 20 and changes surveillance requirements. 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 reinased offsite, and that there is no significant increase in individual ar 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 (58 FR 34073). 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.

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5.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, j

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.

i Principal Contributor:

A. Wang Date:

September 2, 1993 i

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