ML20085N247
| ML20085N247 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 02/12/1971 |
| From: | Hoyt H COMMONWEALTH EDISON CO. |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20085N231 | List: |
| References | |
| NUDOCS 8311100339 | |
| Download: ML20085N247 (3) | |
Text
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Q Commonwealth Edison Company ONE FIRST NATIONAL PLAZA
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February 12, 1971
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- Dr. Peter A. Morris, Director 7
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Division of Reactor Licensing U. S. Atomic Energy Comission
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Washington, D. C. 20545 SUBJ ECT:
LICENSE DPR -25. DRESDEN NUCLEAR POWER STATION UNIT 3, SECTION 6.6.B.3 of TifE TECHNICAL SPECIFICATION.
Dear Mr. Morris:
This is to report a condition relating to the operation of the station in which the total amount of radioactivity in liquid storage in the above ground tanks (Jaste Sample Tanks, Floor Drain Sample Tanks and the 4aste Surge Tank) execeded 3.0 curies and the radioactivity in the "A" Waste Sample Tank ("A" JST) and Jaste surge Tank exceeded 0.7 curies for a period of greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> before recycling'to reduce the radioactivity in these tanks as required by Section 3.8.D. of the Technical Specification.
Problem, Inver,tination and Corrective Action The conditions leading to high radioactivity in the above ground tanks developed on Tuesday, February 2, 1971 when unter in the vaste collector system became high in conductivity as a result of off-standard equipment drainage to system. At that time the cause of off-standard equipment drainage was not_known, The high conductivity water was processed to the Surge tank by-passing the waste dcmineralizer at 5:05 A.M. February 2; to the "A" Waste Sample Tank at 8:45 P.M.
February 2, and to the "B" Waste Sample Tank at 10:57 A.M. February 3, 1971.
Samples were taken on February 3 of each of these tanks (as well as all other above ground tanks) which showed _hinh _ radioactivity as.follows':
"A" WST 1.7 X 10 pCi/1 6
"B" WST 6.2 X 10 pC1/1 Surge 5.5 X 106 pCi/1 An operating order which was issued-November 20, 61970 required special recognition of any tank with a water activity of over 2 X 10 pCi/1.
It required a review of conditions causing the high activity and corrective action as may be j
, appropriate. (The otrder was rewritten February 8 in recognition of the change in DPR-19 on February 5 making it similar to DPR-25).
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February 12, 1971 he need for fr.nediata action was recogni::cd and a program was initiated to necomplish reduction in above ground watcr cctivity by recirculation to below-gr de tanks and i ire
' !~t ' trough the filter and demineralizer until total netN' in w h
...c.d~.).sak was reduced to normal Icvels. A review of operations was also begun u, actum..ine ese source of of f-standard water.
"B" WST was drained to the warte collector at 7:02 P.M. February 3, reprocessed through the filter and deminaralir.or at 11:15 P.M.
The activity of the S
n-ic taken at 2:50 A.M. February 4 Nas 2.3 X 10 pC1/1 (total activity 0.02 C1).
M :o this unter was not acceptable for re-use in the plant it was recycled again.
';u.ce a sample at 8:20 A.M. showed it was still unacceptable for re-use in the plant it was then discharged to the river at a controlled rate.
"A" WST was drained to the waste collector at 7:16 A.M. February 5, reprocesced through the filter and deuincralizer.
The activity of the sampic taken at 4:15 P.M. Fcbruary 5 was 4.5 X 10" pCi/1 (total cetivity.47 C1).
The surge tank uns recycled through the filter and domineralizer at 8:00 P.}L February r and the activity of a sample taken at 12:45 P.M. February 7 was 4.1 X 6
10 (total activity.36 C1).
The individual
- and total above-ground tank water activitics over the period follouing initial conditions are as follous:
2/3/71 2/4/71 2/5/ 71 2/6/71 2/7/71 2/8/71 11 A.M.
8 A.M.
8 A.M.
2 P.M.
11 A.M.
8 A.M.
A '.'ST 1.68 1.68 0.80 0.42 0.01 0.01 Curies B WST 0.71 0.03 0.00 0.00 0.00 0.00 C WST 0.01 0.01 0.00 0.00 0.01 0.00 Surge 1.07 1.07 1.07 1.07 0.36 0.01 A TDST 0.42 0.33 0.33 0.15 0.07 0.16 Jt rn0_T 0.35 0.?3
_0.23 0.19
__0.16
_0.05 Total 4.24 3.35 2.43 1.83 0.61 0.23 Curies
- Individual activities raay be interpolated values based on most applicabic sampic analyses whenever tanks are in the process of being filled or drained.
Water was reprccessed to reduce activity at the maximum rate consistent with maintaining adequate below-grade tank voluces to handic continued plant input.
'Ihe plant input was held to a minimum by limiting reactor pouer and deferring actions such as condensato damincralizer backwashing.
Ihc action taken to by-pass the demineralizer at the time high conductivity water was initially found in the waste collector was to provide temporary high-conductivity storage while temporarily preserving the devincralizer capability for the subsequent volume of high-activity low-conductivity unter. As waste collector water conductivity improved, the tank ("B" WST) of lowest conductivity was processed first in order to dcmineralize the highest total volume of water before the resin bed depleted.
This action resulted in a greater total reserve volume in the radwaste plant.
The resins in the waste dcmineralizer were replaced as required until activitics in above-ground tanks were normal.
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or. Fecer Morris, Uirp February 12, 1971 The need to evaluate plant operations in terms of the effects on radwaste operation he,s been re-emphasien.cne-.c:_r to detect and identify any abnormal effects on radwaste plant operaticas. W Investigation of the sources of high conductivity vater revealed two major sources.
The first source was identified as improper routtna dj;rJn7 construction of the Unit 3.chut33own heat-in:chan than to the ficor drain su% ger" Wil drains to the equipment drain tank rather
- w as cella for in the design.
The 3A shutdown heat ex-changer shell, which normally cona ; closed cooling water inhibited with sodium nitrite, was drained to permit het..ag of the unit 3 reactor water for recirculation tests.
This resulted in one heat exchanger volu:n of the closed cooling system water to drain to the waste collector via t'aa reactor building equipent drain tank.
These lines were rerouted, as designed, to the floor drain system. ca February 6,1971.
A second source of high conductivity water was due to drainage of water from the Unit 3 HPCI system to a drain which caused high conductivity water from the i
floor to flow to the waste collector system.
This area was c1 caned so that any further leakage er erciat,;e weuld net contru.c.cte the waste collector system with high con-ductivity. eater.
One source of high activity in the waste co11cetor was found to be relief valve Icakage on a Unit 2 reactor water cleanup system heat exchanger.
This was repnited on February 7,1971.
Further chtchs cre beir:g conducted for any other potential sources of this type of wat er te the waste colicetor system so that appropriate action can be tchen if required.
In addition a complete review of plant input volutncs to radwaste is being planned, involving installatica of instrumentation and rample lines now planned for the forthcoming refueling outoge of Unit 2.
No uncontrolled or unplar.ned release has occurred as a result of this situation.
The progrm was reviewed by the Station Review Borrd on February 5 and by Atoaic Energy Commission compliance and DRL representatives on February 8,1971.
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