ML17252A353
| ML17252A353 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 12/21/1977 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | James Keppler NRC/RGN-III |
| References | |
| BBS LTR #1202-77 | |
| Download: ML17252A353 (2) | |
Text
. Commonwealtfl9ison
- Dresden Nuclear Power Station R.R. #1 Morris, llHnois 60450 Telephone 815/942-2920 BBS LTR #i202-7~
James G. Keppler, Regional Director December* 21, 1977 Directorate of Regulatory-Operations - Region I I I U.. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen.Ellyn, IL 60137 This letter is submitted to clarify our 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> notif icaiion submitted or:i 12-7-77 at 1011.0 hrs. concerning a nobl*e gas release greater than the Technical Specification limit.
During steady state operation on December*6, 1977, Dresden Unit 3 e~
perienced a main condenser air leak.
This necessitated a. load reduction which began at 0856 hrs.
By 0935 hrs. steam jet a.ir ejector flow ha~
increased from 100 to 200 SCFM.
This lciad reduceion continued and at 1007 it became necessary to bypass the charcoal adsorbers because of high diff-erential pressure and potential damage to the system.
During removal of the charcoal system from service the chimney monitor increased to a reading corr~sponding to 2 Ci/sec noble gas release on the' chimney monitor response curve.
Our 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> notification was based on this response curve.
The turbine was tripped at 1033 hrs~ and the reactor scrammed 6n low vacuum
. shortly thereafter.
Upon further investigation and recalibration, we have modified our chimney monitor response curve.
Using this new curve the chimney monitor reading during the release corresponds to 0.32 Ci/sec, well below our Technical Specification limit of 0.7 Ci/sec.
The recalibration method consisted of v~rifying linear response of the chimney monitor using various strength g:~l3f/, sources and fitting th.e linear curve through the monitor response from samples col.lected from the chimn~y. The samples used for this fit were comp'arable in isotopiccomposition to those experienced during this type of.noble gas release.
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Siince the Technical Specification noble gas' release'lim1it was not exceeded, this event is not reportable by Technical Specification 6.6.B.l.(b).
jp*
Sincerely,
. 8, cf>, ~for-/;),/
7'c;J;;..
B.B. Stephenson Station Superintendent _
Dresden Nuclear Power Station BBS:dlz cc:
B. Lee F. Palmer B. Shelton D. Adam D~~ect~r, Office of l~spection & E~for~ern~nt/NRC Director, Office of Management Information & Program Control/NRC Chief, Division Nuclear Safety Dept. of Public Health - State of Ill.