ML19254C665
| ML19254C665 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 09/14/1979 |
| From: | Moody D Maine Yankee |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 7910170080 | |
| Download: ML19254C665 (4) | |
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TURNPlKE ROAD (RT. 9) 2 ENGINEERING OFFICE WESTBORO, MASSACHUSETTS 01581 617-366-9011
%sO B.4.2.1 WMY 79-95 September 14, 1979 United States Nuclear Regulatory Cot:: mission Office of Inspection and Enforcement Region I King of Prussia, Pennsylvania 19406 Attention: Mr.Boyce H. Grier, Director
Reference:
(a) License No. DPR-36 (Doc!.et 50-309)
(b) USNRC Letter to MYAPC aated August 13, 1979 I&E Bulletin 79-21
Dear Sir:
Subject:
Response to I & E Bulletin 79-21 The information contained in Attachment A is submitted in response to IE Bulletin 79-21.
The responses are numbered corresponding to the bulletin paragraph numbers as listed under " Action to be Taken by Licensees".
Should any additional information be required, please contact us.
Sincerely, MAINE YANKEE ATOMIC POWER COMPANY Ynd&
D.
. Moody
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Manager of Operations EJ:cjp 11C(
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Attachment A 9
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Two liquid level measuring systems within containment are used for safety actions or post-accident monitoring information.
a.
Steam Generator Level uses a vented reference leg open to the top of the Steam Generator and a Fischer & Porter differential pressure transmit ter.
This t.ystem is used to provide a' low-level trip input for the Reactor Protective System.
It is not required for post-accident.
b.
Pressurizer Level uses a vented reference leg open to the top of the pressurizer and a Fischer & Porter differential pressure traas mitter.
This system is used far pressurizer heater control and pressurizer level control and post-accident monitoring.
2.
An evaluation of the effects of post-accident ambient temperatures on these level systems has been done.
The results are shown below.
Corrections to Level, % of Soan a)
Steam Generator Ambient 120 F 0%
Level Reactor Trip 140 F 0.710%
Accident 280 F 8.300%
b) Pressurizer Ambient 120 F 0%
Level Accident 280 F 12.430%
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Basis:
Steam Generator Pressurizer
---Level--
---Level--
Level Calibration Pressure 850 psig 2235 psig Level Calibration Temperature 120 F 120 F 3.
The review of the steam generator level setpoints shows that a violation of the technical specification limits occurs at a temperature of 236 F during the transients reviewed.
The violation of technical specifications occurs fifteen seconds after a reactor trip on containment pressure (temperatu-- at 140 F) has occ : red.
Therefore, the safety function of the level. trip is no longer required.
The ef fect to the S.G.
low level sccpoint is shown below.
Tech Spec Limit Center line of feed ring Safety System Setting Cener line of feed ring plus 10.7" W.C.
Error at 140 F 1.370" W.C.
Error at 236 ?
10.7" W.C.
Error at 230 F 15.98" W.C.
Margin at 280 F
-5.280" W.C.
No safety function nor technical specification limits are associated with the control function of the pressurizer level control system except for post-accident monitoring.
No credit is taken for operation of ty 1 1 I' O 7'n
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pressurizer level related system during or af ter an accident.
Therefore, the effect on this system during an accident need not be analyzed.
The effect on the post accident monitoring readings are listed below.
Error at 140 F 4.070" W.C.
Error at 280 F 44.750" W.C.
4..
The review and evaluation of Items 1, 2, and 3 has been completed and problem with the method of calculating the correction factors suggested by this Bulletin has arisen.
Maine Yankee feels in order to properly address the potential for and magnitude of erroneous level signals additional items must be considered.
This includes the effect of various temperatures and pressures on the variable leg of level systems during the reference leg transient already addresed.
We propose to review this effect on the variable leg and send a reply to you on Item 4 with completion dates for revision of procedures and operator training on these revisions, when the re:iew has been completed.
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