ML20039F883
| ML20039F883 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 12/18/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20039F882 | List: |
| References | |
| NUDOCS 8201140012 | |
| Download: ML20039F883 (5) | |
Text
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SAFELY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 75 TO PROVISIONAL OPERATING LICENSE NO. DPR-29 AMENDMENT N0. 68 TO FACILITY OPERATING LICENSE N0. DPR-30 COMMONWEALTH EDIS0N COMPANY _
AND IOWA-ILLIN0IS GAS AND ELECTRIC COMPANY Q'JAD CITIES STATION UNIT NOS.1 AND 2 DOCKET N05. 50-254 AND 50-265 INTRODUCTION By letter dated December 3,1981 Commonwealth Edison Company (the licensee) proposed a temporary change to Appendix A, Technical Specifications, to Facility Operating Licenses DPR-29 and DPR-30 for Quad Cities Units 1 and 2 respectively.
On November 21, 1981 a leak was discovered in the underground portion of the Unit 1 RHR loop "A" Service Water Line. Unit 1 was in an outage at the time and could not restart because of failure to meet a Technical Specification (T/S) requirement for two operable RHR containment cooling loops.
In order to meet the T/S requirement, the RHR Service Water Pumps "A" and "B" from Unit 2 were made available to Unit 1 by utilizing a cross-tie line (see Figure 1).
Unit 2 was in a refueling outage at the time and this equipment (RHR SW pumps A & B) was not required to be operable for Unit 2.
- However, the T/S precludes any refueling work that has the potential for draining the vessel unless the low-pressure core cooling and containment cooling systems are operable.
EVALUATION The licensee proposes a temporary T/S modification that allows the RHR containment cooling loop "A" for Unit 2 to be defined as operable for Unit 2 while the cross-tie line is connected to Unit 1.
The T/S amendment will allow the use of the cross-tie until June 1,1982, at which time the repair of the Unit i RHR loop "A" service water line will be completed.
The containment cooling mode of the RHR system for each unit consists of two loops as shown in Figure 1.
Each loop consists of one heat exchanger, two RHR pumps, associated valves, piping, electrical equipment and instru-menta tion. The "B" loop on each unit contains two RHR service water pumps.
Normally the "A" loop on each unit also contains two RHR service water pumps. However, during the time interval from November 24, 1981 to June 1, 1982 the "A" loop on each unit may utilize the "A" and "B" RHR service water pumps from Unit 2.
Service water from Unit 2 to Unit 1 will be delivered via the cross-tie line. Loss of one loop of the containment cooling mode of the RHR system leaves the remaining loop to perform the containment cooling function.
Either loop of the RHR system can satisfy the containment cooling function.
8201140012 811218 PDR ADOCK 05000254 P
i
. As stated in the Quad Cities FSAR, only one RHR and one RHR service water pump are required to provide contairment cooling following a loss-of-coolant accident (LOCA) on one unit. One RHR and one RHR service water pump are also adequate to place and maintain the other unit in the cold shutdown condition. Adequate containment cooling is therefore available in the event of a design basis LOCA concurrent with a loss of offsite power (LOOP) and the worst single failure, if one RHR and one RHR service water pump are available.
If the Unit 1/2 (swing) D/G or Unit 2 D/G is postulated as the single failure, along with a Loss of Offsite Power, the modification results in no change to existing procedures or to the existing design basis.
If the Unit 1 D/G is postulated to fail, the original design basis is met with the proposed changes since procedure changes and electrical modifications have been proposed to assure that adequate power is allocated to the necessary equipment during a loss of Offsite Power.
A procedure will be implemented which will allow Buses 13-1 and 23-1 to be energized by D/G 1/2 at the same time (see Figure 2). This will permit one Unit 2 RHR service water pump and one Unit 1 RHR pump to be powered by the D/G 1/2. This procedure would require that the ECCS pumps on Bus 23-1 be pulled-to-lock (prevented from auto starting) prior to closing two locally mounted control switches (as described below) which permit both buses to be energized by the 1/2 diesel.
To permit 1/2 D/G to supply Bus 13-1 on Unit 1 and Bus 23-1 on Unit 2 at the same time, a breaker position interlock in the closing circuit of either one of the two 1/2 DG output breakers must be bypassed when the redundant breaker is already closed. This action is accomplished in either 1/2 DG output breaker by means of a control switch which is physically and electrically independent of its redundant counterpart. Once the breaker position interlock is bypassed in the 1/2 DG output breaker that is open, the operator will then be able to close this output breaker from the control room.
To minimize the probability of operator errors that will leave the bypass control switches in the wrong position, after their function was accomplished, the licensee was advised that we will require that the bypass condition in each breaker closing circuit be automatically removed when the associated 1/2 DG output breaker is opened. The licensee has elected to implement this requirement by providing bypass control switches that are spring-return-to-open. This in essence, automatically removes the bypass as soon as the operator releases the switch from the bypass position. We find this to be an acceptable way to implement our_ requirement in this regard. The licensee has also stated that the bypass control switches will be of the same type as those previously qualified and presently used in existing safety related circuits in the plant.
. The licensee stated that the modification will be fully tested to assure that the 1/2 diesel can energize Bus 23-1 when it is already energizing Bus 13-1, or energize Bus 13-1 when it is already energizing Bus 23-1.
It will also be demonstrated that the closing circuits will revert to the original condition when the bypasses are renoved.
Prior to this modification implenentation, the licensee has cmunitted to write procedures and train operators in the use of this new installation.
We find this temporary modification acceptable because the licensee states and we concur based upon information elicited from the licensee that:
(i) there is ample time, and there will be appropriate procedures and operator training to manually actuate the local switches to initiate the containment cooling function after an event; (2) the RHR containment cooling mode was always designed as a manual action; (3) no originally designed automatic protective features will be adversely affected; and (4) there will be no compromises to core cooling by this temporary modification.
Environmental Considerations We have determined that these amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that these amendments involve an action which is insignificant from the standpoint of environmental impact, and pursuant to 10 CFR Section 51.5(d)(4) that an environmental impact statement, or negative declaration and environmental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of accidents previously considered and do not involve a signifi-cant decrease in a safety margin, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of these amendments will not be inimical to the common defense and security or to the-health and safety of the public.
Dated: December 18, 1981 l
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