IR 05000213/1979021
| ML19309F912 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 02/20/1980 |
| From: | Dante Johnson, Sheldosky J, Thonus L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML19309F902 | List: |
| References | |
| 50-213-79-21, NUDOCS 8005010631 | |
| Download: ML19309F912 (6) | |
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8005 010 (, 3 l U.S. NUCLEAR REGULATORY COMMISSION 0FFICE OF INSPECTION AND ENFORCEMENT g
Region I Report No. 50-213/79-21 Docket No. 50-213 License No. DPR-61 Priority
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Category C
Licensee:
Connecticut Yankee Atomic Power Company P. O. Box 270 Hartford, Connecticut 06101 Facility Name:
Haddam Neck Plant Inspection at:
Haddam, Connecticut Inspection conducted:
De mber 17-20,1979 Inspectors: h
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'D: Fg(/00 Reactor Inspector
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. T: Shedlosky dent Inspector date signed y
tone Point Station)
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L. H. Thonus, Radiation Specialist date signed Approved by:
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/. R. KeImig, @ Branch ef, Reactor Projects Section date signed No. 1, RO&NS Inspection Summary:
Inspection on December 17-20, 1979 (Report No. 50-213/79-21)
Areas Inspected:
Special, unannounced inspection conducted by inspectors dispatched to tne site in response to a release of radioactive materials through the plant vent stack on December 16, 1979. The inspection involved 81 inspec-tor-hours onsite by three NRC inspectors.
Results:
One item of noncompliance was identified in one area (Environmental Technical Specification 2.4.3.1 - release limit was exceeded, Paragraph 3).
l Region I Form 12
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(Rev. April 77)
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DETAILS 1.
Persons Contacted The below listed technicai and supervisory level personnel were among those contacted:
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- R. Blewett, Quality Assurance Supervisor
- N. Burnett, Operations Supervisor J. Ferguson, Station Services Superintendent R. Gracie, Operations Assistant
- R. Graves, Station Superintendent
- J. Levine, Engineering Supervisor
- M. Quinn, Chemist R. Traggio, Unit Superintendent J. Waters, Chemistry Foreman N. Young, Shift Supervisor
- denotes those present at the exit interview.
The inspectors also interviewed several other licensee and contractor employees including members of the health physics, chemistry, operations, and training departments.
2.
Review of the Incident The inspectors were dispatched to the site to review an incident which occurred on December 16, 1979, and resulted in the release of radioactive materials to the environment through the plant vent stack.
During this inspection, observations were made of plant equipment and systems, reviews perfonned of radiochemistry data calculations, equipment calibrations, and radiation surveys.
Prior to the incident which occurred at 0548 hours0.00634 days <br />0.152 hours <br />9.060847e-4 weeks <br />2.08514e-4 months <br /> on December 16, the reactor was operating at 98% power. Turbine stop valve and control valve surveillance testing had been completed and reactor power was being increased by performing dilutions to the reactor coolant system.
Eight thousand nine hundred gallons of water had been pumped to the reactor coolant system and an equal amount let down through the Purification System ion exchangers.
The water which was let down was held in the Primary Drain Tank. The water in the Primary Drain Tank was pumped through the degasifier preheater to the degasifier for stripping of dissolved gases.
The degassed liquid was recirculated through the degasifier preheater and the degasifier.
A portion of this degassed liquid is transferred to the Boron Waste Storage Tanks through a flow control valve (DG-LV-ll53).
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Shortly before 0548, a relay contact in the control logic for valve DG-LV-1153 failed causing the valve to close.
The Degasifier Liquid Transfer pumps continued to recirculate the liquid through the degasifier preheater and degasifier. The Primary Drain Tank pumps, which are controlled by the level in the Primary Drain Tank, continued to fill the degasifier.
These pumps have a shutoff head of 121 psig and filled the 1200 gallon capacity
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degasifier and actuated a rupture disc at 65 psig. The rupture disc is designed to prevent over-pressurization of the degasifier vessel. After the rupture disc actuated, the Primary Drain Tank pumps continued to pump down the Primary Drain Tank at 137 gallons per minute. This liquid flowed from the rupture disc through a 6 inch line, up and across the roof of the primary auxiliary building to the main ventilation exhaust duct and into the plant exhaust stack. The plant exhaust stack supplied by the ventilation and purge fans and the spent fuel building was exhausting a total flow of 52,000 cubic feet per minute.
Based on tank level instruments, it is assumed that 1200 gallons of liquid / steam mixture was pumped at 137 gpm into a ventilation stream of 52,000 cfm.
a.
System and component indications resulting from the incident:
Main stack radiation monitor alarm.
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Steam generator blowdown radiation monitor alarm.
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Containment particulate radiation monitor alarm.
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Waste gas surge tank high level alarm.
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A common trouble alann from the degasifier operations panel in
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primary auxiliary building.
Based upon the above indications the operators terminated dilution of the reactor coolant system and opened applicable drain valves to clear the latter two alarms, b.
Initial investigation and calculations by the licensee revealed the following:
The base of the stack was filled with liquid to a level of four
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feet.
(This water was subsequently pumped into the radwaste system.)
A small leak had occurred at the base of the stack.
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A release of waste gas had occurred lasting about 45 minutes in
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duration containing 19.3 curies primarily from noble gases.
Stack release rate was calculated to be 7.17E + 3 microcuries per
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second.
(141% of the Environmental Technical Specifications (ET/S)2.4.3.l(1)).
Calculated Chi /Q was 1.63E + 4 seconds / meter squared.
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Concentration of noble gases at site boundary was calculated to
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be 1620% of 10 CFR Part 20 limits equating to.4 to.5 mr for one hour.
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Release of iodine or particulates was calculated to be less than
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(ET/S) limits.
Some leakage from the exhaust duct had occurred on the roof of
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the Primary Auxiliary Building through a main exhaust duct flange.
This leakage drained into the yard drain. The activity in the yard drain system was intercepted and pumped to the radwaste system. The yard drain activity leaving the site was analyzed to be less than background.
Notifications
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The licensee initially notified she.:11owing personnel and outside
agencies at the times indicatea on Decemo..- 16, 1979:
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Connecticut Yankee duty officer................ 0900 hours0.0104 days <br />0.25 hours <br />0.00149 weeks <br />3.4245e-4 months <br />
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state uf Connecticut....<..................... 1344 hours0.0156 days <br />0.373 hours <br />0.00222 weeks <br />5.11392e-4 months <br />
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United States Nuclear Regulatory Commission.... 1610 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.12605e-4 months <br />
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Local Offi ci al s................................ 1610 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.12605e-4 months <br />
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3.
Followup Analyses Two strip chart recorders ano a continuous non-recording meter readout a.
were available to the operatars during the event.
The inspector and licensee r!presentatives were able to determine the shape of the curve and time of the release from the available informa-tion.
Comparison of the steam generator blowdown monitor and the i
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stack monitor to external sources provided by the licensee indicated that essentially all of the stack monitor count rate rise was due to gases being sampled, b.
The inspector noted that the stack sampling probe was located in a horizontal rather than a vertical run, in close proximity to the six inch line. There was some release of particulates due to drying of coolant in the horizontal duct and some release of iodines from the coolant at the base of the stack.
These releases were downstream of the sampling point, however, they were well below Technical Specification limits.
The sampling point is located too close to the 6 inch line penetration to assure uniform mixing and is located upstream from a potential release point. This is an unresolved item pending further evaluation (50-213/79-21-01).
c.
The inspector reviewad the licensee's subsequent calculations of noble gas activity released. These were calculated based upon noble gas activity in the primary coolant and the inventory of coolant which could have been degassed during the event.
These calculations indicated that 15.8 curies of noble gase:, were released over a 10 minute time period. This exceeds the licensee's Technical Specification 2.4.3.1(1)
limits by a factor of 5.2.
The inspector identified the above as noncompliance with Technical Specification 2.4.3.1(1) (50-213/79-21-02).
4.
Conclusions The inspector determined the following through interviews with licensee personnel, review of applicable records, and inspection of pertinent systems and components.
There had been no release of radioactive liquids to the environment.
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Ths steam generator blowdown and containment particulate high radiation
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alams were caused by high background radiation from the water in the exhaust duct.
The release of particulate activity was less than 0.1% of the Technical
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Specification limits.
The release of iodine activity was less than 15% of the Technical
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Specification limits.
The release rate of noble gases exceeded Technical Specification
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limits by a factor of 5.2 for a 10 minute perio __
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The potential serious radiological consequences of the event dictated
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a far more timely notification to the NRC than was made.
5.
Exit Interview The inspectors met with licensee management representatives (denoted in Paragraph 1) at the conclusion of the inspection on December 20, 1979.
The inspectors summarized the purpose and scope of the inspection and the findings.
Licensee management representatives made the following statements in response to the inspector's concerns:
An individual would be stationed at the radwaste panel during degasification until equipment modifications were made to preclude similar events.
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