ML20205R826
| ML20205R826 | |
| Person / Time | |
|---|---|
| Issue date: | 03/26/1999 |
| From: | Mcgaffigan E NRC COMMISSION (OCM) |
| To: | Vietticook A NRC OFFICE OF THE SECRETARY (SECY) |
| Shared Package | |
| ML20205R797 | List: |
| References | |
| REF-10CFR9.7 SECY-99-079-C, SECY-99-79-C, NUDOCS 9904230337 | |
| Download: ML20205R826 (3) | |
Text
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NOTATION VOTE RESPONSE SHEET TO: Annette Vietti-Cook, Secretary FROM: COMMISSIOAER MCGAFFIGAN
SUBJECT:
SECY-99-079 - REPORT TO CONGRESS ON ABNORMAL OCCURRENCES FOR FISCAL YEAR 1998 Approved I Disapproved Abstain Not Participating COMMENTS: -
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SIGNATURE A )q,(WI DATE Entered on "AS" Yes I No RE DE DR
4 Based on the results of the IPEEE for Quad Cities, Commonwealth Edison Company (Comed),
in addition to its post-fire safe shutdown, added another method to provide reactor water makeup. This method, known as the interim altamative shutdown method, was a risk-reduction method and was installed in March 1997. The staff viewed this action as a positive compensatory measure; however, concerns remained about several fire protection and post-fire safe shutdown implementation weaknesses. After reviewing the IPEEE, the NRC staff met with Comed staff at NRC headquarters on March 31,1997, to discuss the Quad Cities IPEEE. In April 1997, the NRC staff visited the site, gained additional insights related to plant fire vulnerabilities, and made recommendations regarding needed short-term actions.
1 The licensee mbsequently identified concems not related to the IPEEE that could have I impacted the implementation of the post-fire shutdown methodology and declared all post-fire shutdown paths for both units inoperable. The licensee shut down Unit 2 in September 1997 and Unit 1 in December 1997. Subsequently, the NRC allowed the restart of the plants on the basis of its review and inspection of the licensee's interim safe shutdown analysis, post-fire safe shutdown operating procedures, and risk reduction compensatory measures. The staff agreed that this interim shutdown methodology was an adequate short-term measure and was acceptable until full compliance with Appendix R could be achieved. Currently, Comed is completing its safe shutdown analysis optimization study and is instituting modifications that will reduce the number of manual shutdown operator actions that must be taken from outside the control room, improving fire protection features in certain fire risk vulnerable areas of the plant, lmproving unit interdependence, and improving its safe shutdown response timeline estimations.
Currently, Comed's fire protection improvement program is scheduled to be completed by the end of the spring 2000 refueling outage for Unit i and the r;pring 2001 refueling outage for Unit 2.
Event ght re 'o nd post-fire down s'ystem
' she fs difot result in an actual nge orfail of.a safety sysjelih, potential t4severeJwe could challenge plant safe did' exist.
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- 3. Loss of Liould Poison System (LPS) at Bia Rpek Point This event was discussed during the Congressional hearing held on July 30,1998, and received substantial public and media attention.
Big Rock Point was permanently shut down on August 29,1997. The last fuel bundle was removed from the reactor vessel on September 20,1997. On March 27,1998, an unsuccessful attempt was made to empty the contents of the LPS since it was no longer needed. On April 24, 1998, a boroscopic inspection revealed that the discharge pipe of the LPS tank was completely severed approximately 15.2 centimeters (6 inches) above the water line.
The purpose of the LPS was to inject boron into the reactor vessel to shut down the reactor in the event of a failure of the reactor control rod system. The LPS tank is filled with a concentrated solution of sodium pentaborate to accomplish the shutdown. The severed pipe rendered the system inoperable. The licensee determined that the probable root cause of the
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Commissioner McGaffiaan's insert on SECY-99-079 1
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Recently, Comed completed its safe shutdown analysis optimization study. The results of this study indicated that, for certain cases, additional systems could have been used for post-fire safe shutdown. In addition, this study concluded that, for fires in certain plant areas, some of the credited shutdown actions could have been taken from inside the control room in lieu of
'having to take these actions from outside the control room. Therefore, the results of this study may demonstrate that the original fire risk estimates reported in the IPEEE were overstated.
The staff has not yet reviewed Comed's revised fire risk assessment.
Based on the,results of this analysis, changes to the plant related to the control room control capability of the safe shutdown makeup pump, station blackout diesel, and the high pressure coolant injection pump are planned. In addition, plant improvements are planned for the 125Vdc breaker control power distribution system and the fire protection features provided for the unit 1 reactor feed pump area in the turbine building.
I Even though the post-fire safe shutdown methodology weaknesses did not result in an actual challenge or failure of a safety system, the potential that a severe fire could challenge the ;
effective implementation of this methodology for certain fire areas did exist. '
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