ML13330B211
| ML13330B211 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/19/1987 |
| From: | Ray H Southern California Edison Co |
| To: | Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| References | |
| NUDOCS 8706010192 | |
| Download: ML13330B211 (4) | |
Text
Southern Ca/ifornia Edison Company P. 0. BOX 128 SAN CLEMENTE, CALfFORNIA 92672 HAROLD B. RAY VICE PRESIDENT & SITE MANAGER May 19, 1987 TELEPHONE SAN ONOFRE 714-368-9470 Mr. John B. Martin, Regional Administrator U. S. Nuclear Regulatory Commission Region V Office 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596-5368
Dear Mr. Martin:
Subject:
Docket No. 50-206 San Onofre Nuclear Generating Station, Unit 1 The purpose of this letter is to confirm information provided by the undersigned to Mr. Jess Crews of your staff in a telephone conversation on May 18, 1987.
This information concerns our intention to require that the San Onofre Unit 1 containment be maintained in a higher level of closure, during certain portions of the current outage, than is required by the Technical Specifications.
Based on discussions with members of your staff, we understand that NRC requirements applicable to the level of containment closure to be maintained when PWR Reactor Coolant System (RCS) water level is being controlled near mid-loop are being reviewed on a generic basis. Since San Onofre Unit 1 is planning on lowering RCS water level to this point beginning on May 20, in order to perform.planned maintenance, we have reviewed our capability to provide a higher level of closure during this period, pending the outcome of the NRC review.
We have not previously required a level of containment closure during an outage that is higher than that required by the Technical Specifications. Therefore, we have had to consider in some detail what effect this closure would have on our ability to successfully complete the outage, including our ability to deal with unplanned developments during the ongoing work. The principle elements of containment closure are:
o The large equipment hatch. This hatch is normally open during an outage, in order to permit transfer of material into and out of containment.
o The normal personnel access, which involves an air lock that may have both doors maintained open.
8706010192 870519 PDR ADOCK 05000206 P
Mr. John May 19, 1987 o
The emergency personnel access, which also involves an air lock that may have both doors maintained open.
o Containment penetrations, including ventilation, fluids and electrical which may be in any state of disassembly or test.
In evaluating our ability to increase the level of containment closure, the following considerations are applicable:
o The logistical impact of restricted access during mid-loop operations. The space inside containment is limited, and our ability to move everything needed inside before commencing mid-loop operation, and to wait to remove material until such operation is completed, is very restricted. Furthermore, unplanned requirements for additional material may develop while at mid-loop.
o Evacuation of personnel inside containment, should the need develop.
o The need to provide utility services (e.g., temporary electrical, breathing air, etc.) to support work inside containment.
o The need to work on.containment penetrations when clearances are provided for work on the associated systems, as applicable.
We have reviewed the elements of containment closure, and the considerations noted above. We have revised our outage plan to provide for a higher level of containment closure when the RCS is at mid-loop, as follows:
o Our current outage plan is for the RCS to be maintained at mid-loop for approximately 22 days, commencing on May 20.
The large equipment hatch will be maintained in its closed position, and secured as required during fuel movement by the Standard Technical Specifications, except:
During the last approximately two days of the mid-loop operation, the hatch will be opened to permit removal of accumulated material from containment to be commenced on a timely basis prior to entry into Mode 4.
For periods of not more than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, the hatch may be opened to permit transfer of material due to unplanned needs, or as required to maintain adequate access inside containment for ongoing work.
Mr. John May 19, 1987 When the large equipment hatch is open during mid-loop operation, provision will be made to ensure that it can be closed within two hours from the time when any uncontrolled draining of the RCS, or loss of Residual Heat Removal operation, occurs. Temporary procedures will be provided to ensure that action to close the hatch is initiated promptly, if required.
o The normal and emergency personnel air locks will be maintained with both doors open, if.needed, with the requirement that the capability be provided to evacuate personnel, disconnect utility services and close at least one door in each air lock within 30 minutes throughout the time that the large equipment hatch is in place, as discussed above.
o Special consideration will be given to the identification and careful control of any actions which could result in uncontrolled draining of the RCS, during mid-loop operations, and such actions will be minimized during the periods when the large equipment hatch is open.
o Work on containment penetrations will continue during mid-loop operations, as planned.
While we conclude that it is appropriate for us to require this higher level of containment closure during the present outage, in consideration of the ongoing review of NRC requirements, there are negative consequences which should be weighed against the benefits to safety, as part of the NRC review. These include:
o The impact on the orderly transfer of material into and out of containment. The effectiveness of radiological controls applied to material moving out of containment in a short time window at the end of mid-loop operations could be decreased, for example.
o The inevitable tendency to transfer more material into containment than will actually be needed, prior to closing the equipment hatch. This has a number of negative impacts, including increased congestion inside containment.
o The reduced ability to quickly evacuate containment, and to gain access for purposes such as firefighting.
Mr. John May 19, 1987 We will monitor the situation during the present outage to ensure that these negative consequences of maintaining a higher level of containment closure during mid-loop operation do not result in unacceptable conditions. However, we do not believe this would be possible during all outage conditions, in general.
If you have any questions or comments, or if you would like additional information, please let me know.
Sincerely, HBR:bam cc:
F. R. Huey (USNRC Senior Resident Inspector, San Onofre)