ML17213A732

Seismic Qualification of Auxiliary Feedwater Sys, Technical Evaluation Rept

ML17213A732
Person / Time
Site:	Saint Lucie
Issue date:	09/17/1982
From:	LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	NRC
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ML17213A730	List: ML17213A732
References
NUDOCS 8211220050
Download: ML17213A732 (11)

Text

September 17, 1982 TECHNICAL EVALUATION REPORT ST LUCIE UNIT 1 SEISMIC- QUALIFICATION OF AUXILIARy FEEDWATER SYSTEM

l. INTRODUCTION Since the accident at Three Mile Island, considerable attention has been focused on the capability of nuclear power plants to reliably remove decay heat. The NRC has recently undertaken Multiplant Action Plan C-14 "Seismic Qualification of AFW Systems" [Ref. 13, which is the subject. of this evaluation.

To implement the first phase of Action Plan C-14, the .ABC issued Generic Letter No. 81-14 "Seismic Qualification of AFW Systems" [Ref. 23, dated February 00, 1981, to all operating PWR licensees. This letter requested each, licensee (1) to conduct a walk-down of non-seismically qualified portions of the AFW system and identify deficiencies amenable to simple actions to improve seismic resistance, and (2) to provide design information regarding the capability of the AFW system to facilitate NRC backfit decisions. 'eismic The licensee of't. Lucie Unit 1 responded with a letter dated September 18, 1981 [Ref. 3]. The licensee's response was found not .to be complete and a

.:Request for Additional Information (RAI) was issued by the NRC, dated April 2, 1982 [Ref. 43. The licensee provided a supplemental response in a letter dated May 6, 1982 [Ref. 5].

This report provides a technical evaluation of the information provided in the licensee's responses to the Generic Letter, and includes a recommendation regarding the need for additional analysis and/o'r upgrading modifications of this plant's AFW system.

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EVA'ATION Information provided in licensee's responses included: /

o Specification of the overall seismic capability of the AFW system.

o Identificat:on of currently non-seismically qualified components of

'he AFW system.

o Discussion of the leve1s of seismic capability of the non-seismically qualified AFW system components.

o Description of the AFW system boundary.

o 'tatus of compliance with seismic related NRC Bulletins and Information Notices.

o Results of walk-down of non-seismically qualified portions of the AFW system. 0 o Additionally, description of methodologies and acceptance criteria for the seismically qualified components.

o Additionally, results of walk-down performed for the anchorages/

"supports for all Class lE electrical equipment.

,We have reviewed the licensee's responses, ano a point-by-point evaluation

'of licensee's responses against Generic Letter's requirements is. provided below.

(1) Seismic Capabilit of AFW S stem Except for those items identified in the following, the AFW system has been designed, constructed and maintained to withstand an SSE utilizing methods and acceptance criteria consistent with that applicable to other safety-related systems in the plant. Presently, those items identified by the licensee as not being fully seismically qualified are evaluated below:

~Ri t -Ih o ~Pi in None

Valv s/Actuators Non

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Power Supplies - one Water Source(s)

None Initiation/Control S stems (a) Local gauges are not seismically qualifieo but the licensee stated that they are not essential .for safety system operation. (b) The control grade automatic initiation circuitry, installed as a post-TMI modification, is not seismically qualified but the licensee stated that it would be upgraded to safety grade and seismic Category I during their outage in September 1981.

We conclude that the initiation/control systems possesses an SSE level of seismic capability upon completion of the upgrade of the control grade automatic initiation circuitry.

Structures The conduit supports and mounting of certain electrical boxes were not qualified by rigorous analysis. However, the licensee inspected the above items in the field. They indicated in their response letter that this inspection verified that, in general, the support systems have conservative support spans and were installed in accordance with National Electrical Code Standards using standard "coamercially available strut material, clamps, U-bolts, and various steel shapes, in conjunction with ANSI C80.1 rigid steel conduit.

This level of design for miscellaneous electrical component supports is consistent with industry practices for. plants of the St. Lucie Unit 1 era. The licensee also stated that these support designs and materials are used universally throughout the nuclear and fossil power plant field as well as other industries and were considered to have adequate seismic resistance at the time of installation. Also, the licensee indicated that industry tests on cable tray/conduit support assemblies based on worst case models indicated that systems supported by commercial grade components similar to those used at St. Lucie Unit 1 remained functional after being subjected to tests which simulated. earthquake conditions. In their best judgment, tho licensee believed that the syste'm would remain functional after.an SSE. In conclusion, we judge that the conduit supports and mounting of certain electrical boxes possess an SSE level of seismic capacity.

Based. on our evaluation, those areas of the AFW system judged not to 0

~/t possess an SSE level capability are identified below:

~Pipin None None o Yalves/Actu tors None 1 None o Water Sources(s) None o Initiation/Control S stems None o Structures None

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In summary, our evaluation indicated. that the AFW system at St. Lucie Unit l possesses an overall level of seismic capability that can withstand an SSE.

Because the primary water source and supply path is seismically qualified, switchover to a secondary water source is not involved.

Information regarding the seismic capability of any alternate decay heat removal system is not required because the AFW system will have an SSE

.level of seismic capability upon the completion of the ongoing upgrade of the initiation/control systems.

Regarding the AFW system boundary, licensee indicated that there is no- branch piping in the flowpath which is required to be isolated in order to perform the AFW system function. There are no other branch p'iping connections to the'FW system. Only normal small bore vents, drains and instrument taps all with root valvos, are provided as an integral part of the AFW system piping. These portions were seismically analyzed with t¹ AFW system piping to meet seismic. Category. I requirements. Therefore, we conclude that the AFW system boundary fully conforms to that required by the Generic Letter.

Th licensee stated that the 4 W system was included within the scope of tho s ismic related NRC Bulletin 79-02, 79-04, 79-07, 79-14, 80-11 and IE Information Notice 80-21.

(2) Walk-Down o. Non-Seismicall Qualified Portions of AFW S stem'.

A field inspection was conducted covering all system components that could not be readily qualified by existing documentation; These items consisted of non-seismically qualified miscellaneous conduit and electrical box supports. The licensee indicated that the as-built support system has considerable seismic resistance, and in their best engineering judgment the licensee believed that the system would remain functional following an SSE.

(3) Additional Information Ahe licensee provided information on the methodologies and acceptance criteria that were used in the seismic design of the seismically qualified 1

portions of the AFW system.

Additionally, licensee decided to extend the inspection and review of electrical equipment support/anchorage to include all major Class lE components for the balance of safety related systems. All major electrical equipment anchorages and cable tray supports were found to be

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satisfactory.

3. CONCLUSIONS Th information contained in licensee's responses to.'GL 81-14 is complete. The licensee conducted a walk-down to cover:all non-seismically qualified portions of the AFW system and did not find any deficiencies. Ip addition, we conclude that the AFW system boundary fully conforms to the.

boundary definition specified'in the Generic Letter.

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Eased on the submitted information, we conclude that the AFN system "

provices a reasonable assurance to p rform its required safety function following the occurrence of an SSE upon completion of the ongoing upgrade of the initiation/control systems. The efore, we recommend that no further action be initiated:egarding re-analysis "and/or mooification of the AFH system of this plant under NRC Multiplant Action C-14.

0 REFERENCES

1. D. G. Eisenhut,.U. S. Nuclear Regulatory Commission, memorandum to H. R.

D nton, "Multiplant Action Plan C-14; Seismic Qualification of Auxiliary Feedwater Systems," February 20, 1981.

2. U.S. Nuclear Regulatory Commission, Generic Letter No.'1-14 to all operating pressurized water reactor licensees, "Seismic Qualification of Auxiliary Feedwater Systems," February 10, 1981.

3. R. E. Uhrig, Florida Power and Light Company,'Letter to D. G. Eisenhut of U.S. Nuclear Regulatory Commission, September 18, 1981.

4. R. A. Clark, USNRC, letter to R. E. Uhrig of Florida Power and Light Company, "Request for Additional Information on Seismic Qualification of the Auxiliary Feedwater System, St. Lucie Unit 1," April 2, 1982.

5. R. E. Uhrig, Florida Power and Light Company, Letter to R. A. Clark of USNRC, Hay 6, 1982.

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