ML20008F436
| ML20008F436 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 03/09/1981 |
| From: | Parker W DUKE POWER CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM NUDOCS 8103130545 | |
| Download: ML20008F436 (4) | |
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Duxe Powen COSIPANY Powra Den.ntxo 422 SocTn Cntacu Sturer, Cuantoriz. N. C. 2sa.42 w ww o. pa c a, s a.
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..c os c-o, March 9, 1981
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3,3 T$'J is ia Mr. Harold R. Denton, Director
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- b Office of Nuclear Reactor Regulation 8'$%h gh U.S. Nuclear Regulatory Commission Washington, D.C.
20555
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Attention:
Mr. B. J. Youngblood, Chief d,
(g/
Licensing Projects Branch No.1 0)
Re: McGuire Nuclear Station Docket Nos. 50-369, 50-370
Dear Mr. Denton:
This letter is being submitted to address two specific areas of concern with regard to NUREG-0737 Item II.F.2., Instrumentation for Detection of Inadequate Core Cooling. Specifically, Attachments 1 and 2, respectively, address, (1) the five open items contained on pages 22-52 of Supplement 4 to the McGuire Safety Evaluation Report and (2) the documentation requirements for Item II.F.2 as delineated in NUREG-0737. As you will note, both attachments contain references to other documents and letters which have been previously submitted.
Please advise, if you have additional questions concerning this information.
Very truly yours, William O. Parker, Jr.
GAC:pw Attachments cc:
T. J. Donat l
N1 Senior Resident Inspector McGuire Nuclear Station J
/ /
-81031305'/5 A
ATTACHMENT 1 McGUIRE NUCLEAR STATION INSTRUMENTATION FOR INADEQUATE CORE COOLING 1.
Conformance of the Reactor Vessel Level System to Regulatory Guide 1.97 is described in the Summary Report submittal in a letter from William O. Parker to Harold R. Denton, dated January 16, 1981. Conformance of the Subcooling Monitor to Regulatory Guide 1.97 will be addressed when the overall compliance with Regulatory Guide 1.97 is submitted in April 23, 1981 which is required as a condition of the McGuire license.
2.
The Subcooling Monitor is currently the only ICC monitoring function per-I formed by the plant computer. The functional specifications for this i
monitor are given on page II-9 of Duke's " Response to TMI Concerns."
The reliability (availability) of the computer is addressed on page II-11 of this same document.
i' Currently there are no modifications planned to the Subcooling Monitor.
3.
As noted in earlier submittal, the saturation margin is displayed on a CRT on the control board. This display is called up by the operator in one of two ways. One method is via keyboard entry on the computer con-trol console. The other is a " quick" call-up feature utilizing one button on the control board. When the keyboard is used, the display re-i mains on the CRT until another keyboard entry is made to call-up some other plant display. The " quick" call-up feature retains the display on the CRT as long as the button is depressed.
In either case, the sub-I cooling margin is continuously monitored. A computer alarm is generated if the margin falls below the alarm setpoint. If this alarm is received, I
one of the first steps taken by the operator is to display the subcooling l
information on the CRT if it is not already being displayed.
4.
A copy of the revised Inadequate Core Cooling Procedure for McGuire was submitted to the NRC on December 3,1980. This procedure has been re-viewed by the NRC Staff and will be used until finalization of the i
training on and implementation of the ICC guidelines prepared by the Westinghouse Owners Group. A schedule for this effort was transmitted to the NRC in a letter dated November 10, 1980 from Robert W. Jurgensen to D. F. Ross. This schedule has been delayed since the initial train ~
ing session _ scheduled for late January has still not-been held. We will l
keep you advised as this schedule as it develops 5.
The normal method of. displaying thermocouple readings is on the control l
board CRT. A hard copy printout of these readings can be made available within 5 minutes as a backup display.
k Additional backup capability for reading the in-core thermocouples is described in letters to Mr. Harold R. Denton, dated September 17, 1980 and October 27, 1980. This method involves connecting a millivolt potentiometer to the local readout panel-in the back of the control room
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to determine thermocouple readings. All of the thermocouples can be read in this manner.
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o AITACEMEST 2 McGUIRE NUCLEAR STATION II.F.2 1.
The instrumentation systems for monitoring of ICC consist of a com-bination of ex! sting and new instrumentation. New instrumentation which was added is the Reactor Vessel Level Indicating System (RVLIS).
This system is described ou pages II-9 and II-10 of the document
" Response to IMI Concerns" and in a letter from William O. Parker to Harold R. Denton dated January 16, 1981.
Existing instrumentation for monitoring of ICC consists of the Sub-cooling Monitor and the in-core thermocouples.
(Note that the term "in-core" is used to describe the thermocouples; however, on Westinghouse plants they are " core exit" thermocouples). A description of the Sub-cooling Monitoring and the in-core thermocouples is contained on pages II-9 through II-11A, " Response to TMI Concerns", and in letters from William O. Parker to Harold R. Denton dated September 17, 1980 and October 27, 1980.
Currently there are no planned modifications to any of the existing instrumentation. Duke is pursuing the feasibility of upgrading the qualification of the thermocouples but this is a relatively long term effort with no defined schedule as yet.
2.
A specific design analysis was not performed to support selection of the Westinghouse reactor vessel water level system; however, the Summary Re-port describing the Westinghouse level system submitted in a letter from William O. Parker to Harold R. Denton on January 16, 1981 contains a de-tailed design analysis of the system. Rather Duke representatives were involved in numerous industry meetings in which various level systems were discussed. The selection of the Westinghouse system was made primarily because it was the only system that offered an acceptable level of reliability and unambiguity and could be installed within the re-quired time frame.
3.
Additional testing programs for the Westinghouse reactor vessel level system aredescribed in Section 4.3 of the Summary Report which was sub-mitted on January 16, 1981.
4 Table 4.1 of the Summary Report submitted on January 16, 1981 addresses the conformance of the RVLIS to Regulatory Guide 1.97 which is consistent with the requirements set forth in Appendix B to NUREG-0737. A description of the conformance of the Subcooling Monitor to Regulatory Guide 1.97 will be submitted with the overall description of compliance with Regulatory j
. Guide 1.97 which is required to be submitted by April 23, 1981 as a condition of the McGuire license.
- 5. _
The Subcooling Monitor is currently the only ICC monitoring function per-formed by the plant computer. The functional specifications for this monitor are given on page II-9 of Duke's " Response to TMI Concerns."
The reliability (availability) of the computer is addressed on page
'II-11 of this same document.
o McGuire Nuclear Station II.F.2 Page 2 6.
The current schedule for delivery of the hardware associated with the RVLIS is April, 1981. Installation, testing and calibration will be complete by January 1, 1982. The Subcooling Monitor is installed and operable.
7.
The current Westinghouse guidelines for ICC which address the use of the reactor vessel level system were submitted to the NRC Staff by letter dated November 10, 1980 from Mr. Robert Jurgensen to Mr. D. F.
Ross. The analysis used to develop these guidelines was submitted to the Staff by letter dated July 17, 1980 from Mr. Cordell Reed to Mr. J. Miller.
8.
The McGuire ICC procedure was submitted to the NRC Staff on December 3, 1980. This procedure does not contain any reference to the reactor vessel level system. The procedure will be revised after all of the following actions have been completed:
(1) Reactor vessel level system installed (2) Training on revised Westinghouse ICC guidelines received by plant personnel (3) NRC review of Westinghouse ICC guidelines completed.
It is anticipate:' that the procedure will be revised primarily to re-flect the use of reactor vessel level as another indication of a trend toward ICC.
9.
There are several items described above that are incomplete at the present tLae; howeve., additional submittals should not be required.
The only area where additional information will be submitted, concerns conformance with Regulatory Guide 1.97, which will be submitted by April 23, 1981 as required by the McGuire license.
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