ML20030B806
| ML20030B806 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 08/05/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20030B802 | List: |
| References | |
| TASK-2.E.4.2, TASK-TM NUDOCS 8108240235 | |
| Download: ML20030B806 (3) | |
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ENCLOSURE 3 UNITED STATES
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SAFETV EVALUATICN BY THE OFFICE OF NUCLEM REACTOR REGU'LATION RELATEDTOCONFORMANCEJOSTANDARDREVIEWPLAN6.2.4 REVISION 1 AND BRANCH TECHNICAL POSITION CSB 6-4 REVISION 1 AND TMI ACTION ITEM II.E.4.2.5 ALABAMA POWER COMPANY JOSEPH M. FARLEY NUCLEAR PLANT, UNIT N0. 1 DOCKET NO. 50-348 Introduct f ri During our licensi.ng review of the purge system for Unit No. 2, the licensee proposed installing a three-inch vent line in addition to the eighteen and forty-eight inch purge lines. The purpose of_tbe three-inch line would be to reduce tre use of the large purge lines by ver, ting pressure buildup.
inside contair. ment through the three-inch line.
The licensee also proposed installing chree isolation valves in series in tre vent line, instead of the normal two valves, to improve the reliability of vent line isolation. The three-inci. vent valves won'd be cesigned to satisfy the operability critaria set forth in Branch Technical Position (BTP) CSB 6-4 The licensee committed to install tne three-inch vent line during the next refueling cutage /at out March 1982).
In the interim, the licensee will use the eighteen-inch purge system for both ccntainment purging and venting when at reacto coc ent temperatures abom 200 F.
The eighteen-inch purge system valves b.we 7een blocked to open no greater than 50 degrees on an interim basis catil ;he icng-term review was cot.;1 ted. We confirmeo this licensee 0
commitment by our letter of July 16, 1980. This interim position allows the eighteen-inch system to be open continuously prior to installation of the three-inch vent line. Also, the licensee has now satis'ied the operability criteria set for*h in BT? CSB 6-4 for the eighteen-inen nurge valve (See separate SER).
They have also verified that the estimated v. cunt of radio-actitity released during the tin,a required to close the ei;nteen-inch purge valves following a LOCA does not cause the total offsite dose to exceed the 10 CFR Part 100 guideline values.
The onuinment isolation actuation si.gnal for containment pressure war evaluated during the Unit No. 2 licensing review.
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Discussion and Evaluation After installation of the three-inch vent line, the use of eighteen-inch purge lines would be reduced "to a goal of about 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> per year.
The three-inch vent line would be open continuously. We consider that such reduced purging time with the eighteen-inch lines and the continuous venting through the three-inch line would be acceptable. However, it is i
necessary that the three-inch vent valves satisfy the operability criteria set forth in BTP CSB 6-4.
The licensee is also studying an alternative design involving the install-
'ation of an eight-inch purge system having :hree isolation valves in series in each line.
The eight-inch purge system would be used in lieu of the three-inch vent line. With continuous operation of the eight-inch purge system, the need for the eighteen-inch ourge system would be drastically reduced, dnd possibly eliminated.
Continuous operation of the eight; inch purge system would also allow immediate personnel entry into the contain-ment for safe.ty related maintenance or surveillance activities. The licen-see estimates that a thirty-hour. delay in containment entry would be asso-ciated with the use of the eighteen-inch purge system and three-inch vent line ombination. The thir.ty hours of purging with the eighteen-inch system would be necessary to reduce radioactivity levels for personnel access to the containment.
We will evalJate the licensee's proposed system desig.1 when submitted on Unit No. 2.
The results of cur evaluation will be discussed in a future Safety Evaluation Report.
The licensee has demonstrated that the containment purge system design assures that blockage of the purga isolation valves will not occur.
The purge supply and exhaust duct openings i.nside containment are covered with a screen to prevent debris from entering the ducts and possibly blocking isolation valve closure. The screen has 1/2-inch square openings and is fabricated from 0.049-inch diameter wire. The screen is attached to the purge duct by welding.
High activity conditions inside containment would be detected prior to opening the purge valves by means of the containment atmosphere particu-late radioactivity monitor (R-ll) and the containment atmosphere gasecus radioactivity monitor (R-12). The output from each detector is transmitted to the Radiation Monitoring System cabinets (located in the control room) wher,e the radiation level is indicated by a meter and continuously record-ed.
Prescribed high radiatior. levels are visually indicated at the Radia-tion Monitoring System cabinets.with audible annunciatien provided at the main control board in the control room.
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i-TMI ' Action Pian Item'II.E.4.2.5 - Containment Pressure Setpoint The containment isolation actuation signal setpoint for contain' ent pressure
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considered by the-licensee to be the minimum level compatible with normal operation is 5.0 psig. - The channel accuracy assumed in the safety analysis
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is +1.8 psi. With a 2.6 psi margin, the normal operating containment pressure can be as high as 0.6 pr -
This value is inconsistent with pressure margins 3,
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observed at other facili
.8 with similar containment d6 signs. We consider the minimum setpoint for containment isolation signal to be 4.0 psig.
This pressure setpoint is-consistent with setpoint pressures at other facilities
- with similar containment cesigns. We included a setpoint of 4.0 psig in the Technical Specification issoed during Unit No. 2 licensing. Therefo re,
with the upgrading of Unit No.1 Technical Specifications to be similar to Unit No. '2, we consider this review as completed.
Concl0sion Cased on our review, we conclude that the purge / vent systen meets the require-ments of SRP 6.2.4 and is acceptable. We also cortlude that the revised containment pressure sctpoint similar to that of Unit 2 is acceptcble for Unit No. 1, the idantical plant design.
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