ML19353A066
| ML19353A066 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 12/18/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Kemper J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| References | |
| NUDOCS 8101070055 | |
| Download: ML19353A066 (1) | |
Text
.
d'gr.e ncoq'o, UNITED STATES IM i}
('j NUCLEAR REGULATORY COMMISSION
- .' \\ ', y/. p HEGION I S.
631 PARK AVENUE
,d,4 KING OF PRUSSIA, PENNSYLVANIA 19:06 y
Docket Nos. 50-352 10 50-353
"~
y wrj Philadelphia Electric Company k
~~
ATTN:
Mr. John S. Kemper W
Vice President Engineering and Research
~
^
2301 Market Street Philadelphia, Pennsylvania 19101 Gentlemen:
The enclosed Supplement No. 4 to IE Bulletin No. 80-17, " Failure of Control Rods to Insert During a Scram at a BUR," is forwarded to you for information.
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, TH/G N, A%- -
yce H. Grier Director
Enclosures:
1.
Supplement No. 4 to IE Bulletin No. 80-17 2.
List of Recently Issued IE Bulletins CONTACT:
D. L. Caphton (215-337-5265) cc w/encis:
V. S. Boyer, Senior Vice President, Nuclear Power 0
SSINS No.:
6820 Acccssion No.:
8006190074 UNITED STATES IEB 80-17 Sup. 4 NUCLEAR REGULATORY Cop 9 FISSION 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 18, 1980 IE Supplement 4 to Bulletin No. 80-17:
FAILURE OF CONTROL R005 TO INSERT DURING A SCRAM AT A BWR NRC staff evaluation of failures of the continuous monitoring system (CMS) for the scram discharge volume (SDV) at an operating BWR has identified the need for licensee actions in addition to those requested bi IEB 80-17 and Supnlements 1-3.
The purpose of these actions is to provide assurance that l
the CMS has been tested to demolistrate operability as installed, remains operable during plant operation, and is periodically surveillance tested to demonstrate continued operability.
The occurrence of CMS failures at Dresden Nuclear Power Station was discussed in IE Information Notice 80-43, which was issued on December 5, 1980 to those operating BWR's with CMS recently installed.
Subsequently, investigation into the cause of the failure to receive the alarm with the SDV essentially full revealed several items which required correction, including:
1.
Excess portions of transducer cable were placed in physical positions which would increase external noise sensitivity.
2.
The UT transducers were not placed in a physical position to optimize system sensitivity.
3.
A certain amount of " cross-talk" was occuring between redundant trans-ducers located a few feet apart on the same run of 4" pipe.
Station and vendor personnel shortened and rerouted transducer cables to improve noise rejection.
Vendor specialists optimized transducr.r placement and synchronized both transducers to the same ultrasonic ir.strument internal clock 2
to minimize cross-talk and improve signal to noise characteristics.
Following these actions the CMS appeared to function properly.
Further difficulties were encountered when apparently minor quantities of water leaked into the SDV as a result of control rod drive scram valve maintenance activities and minor scram outlet valve leakage.
It appears that the trans-ducers are located on a section of SDV piping which forms a local low point.
Accordingly, small amounts of water can accumulate to a depth which triggers the high level alarm (at 1-1/4") before the water drains to the instrument volume.
The licensee in conjunction with the NSSS vendor, performed a unit specific analysis for a conservative t* *
^-
point to 2-1/2".
The system now appe alarm time delay was also installed 1
DUPLICATE DOCUMENT r
Entire document previously i
(
entered into system under:
F ANo 900G t 9o crP No. of ages:
=
w=== =
m -e -
. =
-