ML20214F587

SER Granting Util 870422 Request for Approval of Plans Allowing Removal of Reactor Pressure Vessel Head Spray & Vent Piping & Detensioning Reactor Pressure Vessel Head Studs Prior to Connecting Standby Gas Treatment Sys

ML20214F587
Person / Time
Site:	Limerick
Issue date:	05/18/1987
From:	NRC
To:
Shared Package
ML20214F576	List: ML20214F575 ML20214F587
References
TAC-65146, NUDOCS 8705260166
Download: ML20214F587 (2)

Text

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, , , ENCLOSURE

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SAFETY EVALUATION REPORT LIMERICK GENERATING STATION UNIT 1 REMOVAL OF REACTOR HEAD SPRAY AND VENT PIPING AND VESSEL STUD DETENSIONING DOCKET NO. 50-352 (TAC 651461

1. INTRODUCTION By letter dated April 22, 1987, the Philadelphia Electric Company submitted a reouest to allow removal of the RPV head spray and vent piping and detensioning the RPV head studs prior to connecting the SGTS to the refueling area.

1he licensee had previously riade comitments that neither the primary containment head nor the reactor vessel head would be removed, without prior URC approval, before the SGTS is connected to the refueling floor zone. The NRC staff incorporated a portion of this commitment dealing with the reactor vessel head into license condition 2.c(14) as discussed in Section 6.2.3 of SSER-3.

By letter dated March 19, 1987, the licensee submitted a request removal of the primary containment head prior to connecting the SGTS to the refueling area. The NRC staff reviewed this submittal and issued an evaluation dated May 8,1987 which approved this operational procedures.

2. EVALUATION The staff's approval of the licensee's March 19, 1987 request, was based in part on the fact that the RPV would remain' intact. However, the licensee's April 22, 1987 request would allow a 6" line and a 4" line on the RPV to be temporarily open without the connection of SGTS to the refueling area. The licensee proposed to install blank flanges or HEPA filters imediately upon breaching the flanged connections between the 6" RPV head spray and the 4" vent piping and the reactor vessel, to prevent any substantial untreated release from the RPV.

The SGTS at Limerick Unit 1 is currenti connected to the Unit i reactor enclosure secondary containment (Zone I , but not to the refueling area {

secondary containment (Zone II). The licensee, during the refueling outage, '

plans to replace the 3000 cfm fans with 8400 cfm fans and associated ductwork to allow coverage of all zones. During the outage, until the 8400 cfm fans are installed and tested, the licensee plans to align the 3000 cfm fans from Zone I to Zone III. It is after plant shutdown while in Modes 4 and 5, but  ;

before this realignment is accomplished, that the licensees NRC approval to proceed without SGTS.

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8705260166 DR 870518 ADOCK 05000352 -

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The licensee has proposed this procedure because it is helievcd that the r(lief from the current operating restrictions represents cnly a minor chance. The basis of this belief is based on the following rationale.

(1) Dreaching of the flanged connections of the 6" RPV head spray and 4" "ent piping is only for e very short tire. The licensee proposes to imediately install blenk flances cr HEPA fi'ters on these cpenings.

Therefore, the potertini for an untreated radicactive re' ease would he of sufficiertly low prchability to be considered acceptable.

(2) The reactor frei will remain in core entil the SGTS is connected. Also, the RtV head is not temoved. Geroval of the 6" RPV head spray and the 4" vent piping and detensioning the RPV head studs therefore can not result in (a hoe.vy load drop to cause) fuel damage, requiring the use of the SGTS to control the release of radiation.

(3) Vorkers in the refueling area are protected by continuous air crd floor radiatier ronitoring and health physics surveys are cerducted when the piping is coroletely removed.

(4) Thf licensee and the sta" have both performed of# site radiological dose analysis. A 10% fuel gap activity release to the reactor coolant was assured according to P,egulatory Guide 1.25. The results based on an eight hour assumed unfiltered release shows that the thyroid dose was below the 10 CFR 20 limit. Additionally, the licensee's recent sartpling of the reactor coolant ir.dicates a lever coolant activity level than assumed fer this analysis.

3. CONCLUSION The staff has reviewed this rationale and concurs W th the 'icersee that the reevested change represents a small change in the crcrating procedures. Or the basis of the above evaluation, the sta#f concludes that renovel of the 6" RPV Frcd spray and the 4" vent piping and detensionino the PPV head studs prior to connecting SGTS to the refuelir.c area, will rot endancer the safety and herith of the workers in the crea or that of the general public. The staff approves this recuest as proposed and also reminds the licersee that, as required by the testing procedures (Refueling Area Secondary rcr.tainment Integrity Verification (ST-6-076-360-0)'l, the SGTS trust be connected to 7cre

!!I and be tcsted before the total terrevai of the RPV head.

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