ML20246F866
| ML20246F866 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/23/1989 |
| From: | Hukill H GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C311-89-2059, IEB-79-27, NUDOCS 8908310154 | |
| Download: ML20246F866 (2) | |
Text
t-3( k-GPU Nuclear Corporation Nuclear
=, oms:reo Middletown, Pennsylvania 17057-0191 l
717 944-7621 TELEX 84-2386 Writer's Direct Dial Number:
C311-89-2059' l
Aucgst 23, 1989 U. S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, DC 20555
Dear Sir:
Three Mile Island Nuclear Station, Unit 1 (TMI-1)
Operating License No. DPR-50 Docket No. 50-289 GPUN Clarification Regarding Commitments from Inspection Report (IR) 88-28 and'the NRC's Audit of IE Bulletin 79-27 Conformance l
The NRC's letter of May 2, 1989 gave the results from an NRC audit conducted du' ring the week of October 31, 1988 regarding GPUN'conformance to the guidance contained in IE Bulletin 79-27.
i This audit was also addressed in IR 88-28.
Included in the NRC's May 2, 1989 letter were recommendations for additional preventive maintenance and testing for devices that perform automatic switching of electrical buses from one power sourra to another.
The purpose of this letter is to inform the NRC of tis actions GPUN has taken and clarify an issue regarding the "1M" bus automatic bus transfer switch (ABT) which does not appear to have j
been resolved as discussed during the audit.
We believe that the l
additional testing that has been. incorporated satisfies our commitments as discussed during the audit and as reflected in Inspection Report (IR) 88-28.
At the time of the audit, procedural changes were in progress to Preventive Maintenance Procedure E-26, " Cleaning and Alignment of Inverters" and Corrective Maintenance Procedure 1420-INV-3,
" Inverter, Troubleshooting and Alignment" to incorporate additional requirements as part of another activity separate from the NRC's audit.
E-26, which is performed each refueling interval, was being revised to include requirements for verification of the static switch transfer function during the alignment and verification of single phase static switches in accordance with Corrective Maintenance Procedure 1420-INV-3.
These changes were incorporated into procedures E-26 (Revision 8, effective 1/16/89) and 1420-INV-3 (Revision 10, effective 2/1/89).
IR 88-28 stated GPUN's commitment from the audit regarding the AC to DC transfer function for the inverters tested under Surveillance Procedure 1303-11.10 during "]D" or "1E" 8908310154 890823
<'EA/
PDR ADDCK 05000289 G
PNU
,g GPU Nuclear Corporation is a subsidiary of the General Public Utilities Corporation
L S
'C3'1l-89-2059 4160-volt AC vital de-energization.
During the audit GPUN committed to incorporate a verification sign-off and acceptance criteria to document this transfer.
l It was our understanding from discussions during the audit that l
the NRC had agreed the "lM" bus ABT does not need to be tested because this transfer does not provide a safety function.
The transfer device associated with the "lM" bus is blocked on an Engineered Safeguards (ES) actuation.
This understanding was also reflected in IR 88-28, Section 5.1, where the NRC accepted the periodic test of the blocking relay in accordance with surveillance Procedure 1303-5.2, " Loading Sequence and Component Test and HPI" because the blocking relay is the last active component to prevent transfer.
In response to Inspection Report 88-28 (OI Number 88-28-01),
Revision 21 to surveillance Procedure 1303-11.10, "ES System Emergency Sequence and Power Transfer Test", incorporated additional requirements with appropriate acceptance criteria and sign-offs to verify transfer of the five station inverters from their normal supply to the station battery.
Thus, we believe that all required actions regarding the recommendations contained in the NRC's May 2, 1989 audit report on TMI-l conformance with IE Bulletin 79-27 are complete and that additional tests of the ABT associated with the "lM" bus are not required.
Sincerely, f
7 V
. D. Hukill Vice President and Director, TMI-l HDH/MRK cc: J. Stolz R. Hernan F. Young W. Russell