ML20210E189

Safety Evaluation Considers SEP Topic III-5.B to Be Complete in That If Pipe Breaks Outside Containment,Plant Can Safely Shut Down W/O Loss of Containment Integrity

ML20210E189
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	06/12/1992
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20210E163	List: ML20210E159 ML20210E189
References
TASK-03-05.B, TASK-3-5.B, TASK-RR NUDOCS 9206180397
Download: ML20210E189 (3)

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SAFETY EVALUATION BY-THE OFFICE OF NUCLEAR REACTOR REGULATION CONNECTICilT YANKEE ATOMIC POWER COMPANY HADDAM NECK PLANT DOCKET NO. 50-213

1.0 INTRODUCTION

l An evaluation performed by the staff as part of the Systematic Evaluation Program (SEP) under SEP= Topic III-5.B, " Pipe Break Outside Containment" was

-forwarded to Connecticut Yankee Atomic Power Company-(CYAPC0/the licensee) by letter dated May 10, 1982. This evaluation identified the following four issues concerning pipe breaks outside containment which were not adequately addressed:

(1) CYAPC0 needs to verify that flooding and spray effects have been fully addressed, (2) CYAPC0 needs to. evaluate postulated breaks in the auxiliary feedwater system, (3) CYAPC0 needs. to clarify the jet impingement criteria used in the evaluation of piping in the primary auxiliary building (PAB), and (4) CYAPC0 needs to evaluate the effects of postulated turbine extraction steam line breaks on the switchgear room.

By letters dated November 18, 1986, October 23,-1987 and April 1, 1992, CYAPC0

- responded to the above issues.- An evaluation of these responses is provided bel ow.-

2.0= EVALUATION 2.1 Floodina and Soray Effects By letters dated February 5 and 12, 1975, CYAPC0 provided the staff with their review of, the effects-of-flooding and spray from a high energy line break -

outside containment. The-licensee concluded that the rupture of a high pressure water-carrying. pipeline could not damage more than one of the several methods _available for_ safe shutdown of the plant. The licensee has stated that equipment' configuration is such that-flooding and spray effects from a line break can only affect-the pump associated with the break, which is

already disabled by the break.. In addition, CYAPC0 has completed several modifications -including liquid level detectors, dikes, barriers at floor openings, door louvers,'and expansion joint sleeves to protect safety-related equipment from potential flooding.

Based on the above the staff has concluded 9206180397 920612 PDR ADOCK 05000213 P

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that'the effects of flooding and spray due to high energy line breaks outside containment has been-adequately addressed.

2,2 Postulated Breaks' in A0xiliary-Feedwater System By License Amendment-No. 149 dated February 24, 1992, the staff resolved the high energy line break issue for postulated breaks in the auxiliary feedwater (AFW) system. CYAPC0 has proposed a dedicated erosion / corrosion program for the Terry turbine' building piping.to reduce the probability of the high energy i

-line break. -In_ addition, CYAPCO will 1) install an: electric driven auxiliary

-feedwater pump, powered by an emergency onsite power source, 2) provide a direct injection path-for AFW flow into the steam generators, 3) dedicate the demineralized water tank to_the AFW system and 4) house the.new electric AFW pump,-the automatic initiation support skids and direct injection piping and valves.in a new seismically designed enclosure.

Based on the above, the staff agrees. that:the high energy line break in AFW piping issue is resolved.

2.3 : Jet Imoinaement Criteria Bycletter' dated December 12,-1986, the staff identified an issue concerning the jet; impingement criteria used in the evaluation of piping in the primary auxiliary building.

By letters dated November 18,-1986, October 23,_1987, and April: 1,1992,:CYAPC0 provided a discussion of protection against pipe-break outside containment, which included clarification of the criteria used in evaluating and determining the effects on piping and equipment due to jet impingement. < Based on our review of these submittals, including clarification of the licensee's application of the dynamic amalification factor of 2.0, the

-staff finds the licensee's criteria conform wit 1 the intent-of Standard Review Plan-(SRP) Section-3.6.2, " Determination of Rupture locations and Dynamic Effects Associated with the Postulated Rupture of Piping," Revision 1.

Based on the above-the staff concludes that this issue regarding jet-impingement' criteria is resolved.

2.4t Evaluation of Effects of Turbine Extraction Steam LinE_ Breaks on the Switchaear Room The switchgear room is separated from the turbine extraction steam lines by a 12-inch-thick filled concrete block wall backed by a %-inch thick steel plate with integral stiffeners. The steel plate is in contact with the conciete block wall. The plate' and stiffeners are welded to the main structural load carrying members of the building.

Loads on the wall resulting from a beeak in ca. turbine extraction steam line would act on the concrete block side of the

wall, n

L The licensee evaluated'possible interactions with the switchgear room wall l

resulting from postulated breaks at two locations on the extraction steam line.

Analysis of these break locations indicates that there would be no aiverse reaction with the switchgear room walls due to pipe whip following an extraction steam line break.

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-Additional analysis performed by the licensee has shown that the switchgear room wall system will remain intact when subjected to the jet impingement load resulting from an extraction steam line break acting in conjunction with all credible loads. Therefore, no damage will occur to any components within the switchgear room as a result of the dynamic effects of a turbine extraction steam line break.

This evaluation is consistent with the requirements of General Design Criterion 4 of 10 CFR Part 50, Appendix A and the guidance contained in SRP Section 3.6.1 with regard to protection against the dynamic effects of high energy pipe breaks outside containment.

Therefore, the safety related equipment within the switchgear room is adequately protected against the dynamic effects of postulated turbine extraction steam line breaks.

3.0 CONCLUSION

The staff has completed its review of SEP Topic 111-5.B and concludes that if a pipe were to break outside containment, the plant can safely shutdown without loss of containment integrity.

Based on the above the staff considers SEP Topic 111-5.8 to be complete.

Principal Contributors:

M. Hartzman S. Jones A. Wang Date:

June 12, 1992