IR 05000213/1980009
| ML19344E219 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 06/02/1980 |
| From: | Knapp P, Serabian J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML19344E215 | List: |
| References | |
| 50-213-80-09, 50-213-80-9, NUDOCS 8008280134 | |
| Download: ML19344E219 (9) | |
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O u.s. auC'e^a accu'Aroav comatSSton 0FFICE OF INSPECTION AND ENFORCEMENT Region I Report No.
50-213/80-09 Docket No.
50-213 License No. DPR-61 Priority Category C
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Licensee:
Connecticut Yankee Atomic Power Company P.O. Box 270 Hartford, Connecticut 06101 Facility Name: Haddam Neck Plant Inspection at: Haddam Neck, Connecticut Inspection conducted:
May 4 and 5, 1980 Inspectors:
O 4, bM 4 - 7 -Bo
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E/ A. Serabian, Radiation Specialist date signed date signed
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date signed
% on Av Approved by: \\--e h A
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A J. Knapp, Chief ~,'Radi'a' tion date signed Support Section, FFMS Branch Inspection Summary:
Inspection on May 4 and 5, 1980 (Report No. 50-213/80-09)
Areas Inspected:
Special, announced inspection by one regional based inspector l
l to follow up site noble gas releases, which occurred on May 4, 1980, specifically l
in the areas of notifications; Emergency Plan implementation; and Techr.ical l
Specification release rate limits. The inspection involved eight inspector-
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hours on-site by one NRC regional based inspector.
Resul ts: Of the three areas inspected, no items of noncompliance were found in two areas, one apparent item of noncompliance was found in one area (infrai.!. ion -
failure to adhere to Technical Specification limits regarding noble gas release rates), Paragraph 2.b.(2)(a).
l Region I Form 12 (Rev. April 77) ' 48 0 0 8 28 0 l3 L
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DETAILS 1.
Persons Contacted
- Mr. R. Graves, Station Superintendent, Connecticut Yankee Atomic Power Company (CYAPCo)
- Mr. R. Traggio, Unit Superintendent, CYAPCo
- Mr. J. Ferguson, Station Services Superintendent, CYAPCo Mr. M. Quinn, Chemistry Supervisor, CYAPCo Mr. M. Siegrist, Radiological Assessment Engineer, Northeast Utilities Services Company
- Denotes those present at the exit interview.
2.
Description of Events On May 3 and 4,1980, three unplanned releases of radioactive noble gases were reported by the licensee via telephone to the USNRC Region I (Philadelphia)
Office Duty Officer. The events related to these releases as reported by licensee personnel and examined through on site interviews and inspector review of the Control Room Log Book (for the' period in question) and the licensee's Executive Summary of the events dated May 5,1980, are described in the following.
a.
First Event: May 3, ?9R0 Plant operators were degassing the normal hydrogen cover pressure on the Volume Control Tank with a nitrogen cover pressure, a normal operation incident to refueling. The gas (a mixture comprised of H *
Xe, and Kr) is normally routed to the Waste Gas Surge Tank in a controlled manner where it is eventually processed via the Waste Gas System (which includes the Waste Gas Decay Tanks and HEPA/ Charcoal filter
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banks). The release occurred when the Waste Gas Surge Relief Valve opened briefly, taice, thereby allowing gas to be released directly to the stack.
(See Figure 1.) The licensee's Chemistry Group and (Corporate) Radiological Assessment Branch performed a review of these releases, which indicated that the release constituted about 84% and 51% of the instantaneous release rate limit for noble gases, specified in the Technical Specifications. Approximately one Curie of radioactive noble gases was released.
A conservative dose estimate was also calculated by the licensee and indicated that an individual hypothetically located at the site boundary during the entire period of the release would receive a dose of 0.01 mrem to the whole body.
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Relief to Stack
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Filtration i
and i
Purification i
System e
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Waste w2
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Gas
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Surge lr'
Tank
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w Volume
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s To Waste Gas Control Processing System Tank Normal Release Pathway i
_ _ _ __; Unplanned Release Pathway
Return to Reactor Coolant System Figure 1.
Schematic of the pathway of the unplanned release on May 3, 1980, as reported by licensee representatives.
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Through review of the licensee's telephone notificetion check sheet and discussion with licensee personnel, the inspector verified that the licensee had reported the event (i.e., an unplanned release of radioactivity) to the USNRC in accordance with the reporting require-ments recently promulgated in 10 CFR 50.72, " Notification of Signifi-cant Events".
No items of noncompliance were identified in this area.
b.
Second and Third Events: May 4, 1980 The second and third unplanned releases occurred during the spent resin sluicing and transfer of the "B" Ion Exchanger. The normal evolution for this process involves the transfer (via sluicing) of the spent resin to a spent resin transfer cask, in which the excess liquid'
is simultaneously dewatered.
These liquids (and dissolved noble gases) are routed to the Aerated Drains Tank where the liquids are stored for processing and the gases are vented to the Primary Auxiliary Building (PAB) ventilation system. This ventilation system includes a HEPA/ charcoal filter system.
Releases occur via the plant stack.
(See Figure 2.)
At 7:55 a.m., just after the operator comenced the transfer evolution, the Main Stack (Gas.) Radiation Monitor (RMS-14) alarmed.
(Alicensee representative stated that this monitor is set to alarm at the Tech-nical Specification instantaneous release rate limit for noble gases.)
The transfer evolution was then terminated and the Control Room announced evacuation of any personnel in the PAB. Licensee representatives stated that the alarm cleared about four minutes after annunciation.
At about 8:40 a.m. the monitor had returned to normal stack background radiation levels.
Licensee personnel commenced notification and the actions specified by the emergency plan which applied in this instance.
(Refer to Paragraph 2.b.(1).)
At 9:00 a.m., an operator again commenced the transfer evolution. The Main Stack Gas Radiation Monitor alarmed. The evolution again was terminated and the licensee again commenced the notification and applicable emergency response procedure. The Station Superintendent informed the inspector that, on being informed of the second event, while at home, he orally directed that the sluicing evolution be put on hold until the cause could be established; but, this directive had not yet been conveyed to the (field) operator who comenced the transfer at 9:00 a.m.
The alarm again cleared in about four minutes and had returned to normal stack background radiation levels at 10:15 a.m.
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f From Reactor
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Coolant System Demineralized
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(RCS)
Water Supply
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Noble Gases
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to Stack Via
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Auxiliary Building
"B" Ventilation System
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Ion Exchanger
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Floor Drains
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(Sluiced
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Resins)
u, Charging () Pump Aerated Drains
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and
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Volume Tank Return Control Spent Resin (Dewatering)
to RCS System Shipping
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Container
(Noble Gases Evolve from j
E Water)
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To Liquid Radwaste
- Processing System
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Figure 2.
Schematic of the pathway c/ the unplanned releases on May 4, 1980, during spent resin sluicing and transfer, as reported by licensee representative.
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(1) Notification Through review of the licensee's (relephone) notification check sheets, review of the Control Room Log Book (for May 4, 1980),
and discussion with licensee personnel, the ir.spector verified that the required notifications of the releases to facility, local, state and federal contacts had been made in accordance with 10 CFR 50.72, " Notification of Significant Events", and the Haddam Neck Plant Site Emergency Plan, Section 6.1, " Activation of Emergency Organization".
No items of noncompliance were identified in this area.
(2) Classification On receiving the alarm at 7:55 a.m., the licensee implemented the Site Emergency Plan and, using the plan criteria, classified the releases as Unusual Events.
The inspector reviewed the Haddam Neck Site Emergency Plan, Revision 7, Section 4.1, " Classification". The inspector noted that the licensee's classification of the occurrence of the releases was in accordance with the criteria specified in the plan.
In these instances the " Table {4-1} of Unusual Event Classification" designates exceeding the Radiological Effluent Technical Specifications, as indicated by the Stack Radiation Monitor Alarm, as an Unusual Event.
No items of noncompliance were identified in this area.
(3) Assessment After the circumstances surrounding the releases had been reviewed, a licensee representative informed the inspector of the apparent cause of the releases.
Relatively high concentrations of noble gases had remained in the water inside the isolated ion exchanger.
When the spent resin was sluiced (along with the water in the ion exchanger), the water was routed to the Aerated Drains Tank where the gases evolved from solution and passed back through floor drains to the PAB ventilation, then to the stack. The inspector asked the licensee representative why, in this particular instance, there was a relatively high concentration of noble gases inside the ion exchanger. The licensee representative stated that, it was desired to return the "B" lon Exchanger to service as soon as practicable to be used to further lower the reactor coolant system radioactivity concentrations in preparation for the current refueling outage. The ion exchanger is normally isolated and out of service, after the resin is spent, for about one week to allow i
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the radionuclides with short half-lives, e.g., noble gases, to decay prior to sluicing.
In this instance the ion exchanger had been out of service for only about six to eight hours prior to sluicing so that significant decay of the short half-life noble gases did not occur. The inspector also asked the licensee representative why the floor drains would be a releate path from the Aerated Drains Tank.
A licensee representative stated that a pressure buildup, then sudden release, caused by bypassing a clogged filter during the sluicing evolution, could have been sufficient to force out the floor drain loop seals. The licensee representative stated that all PAB floor drain loop seals had since been re-established.
c.
Assessment of Offsite Releases Through review of radiation monitoring instrumentation strip che < *3 and radiolytic analyses of representative reactor coolant gas sumples, the licensee reported that the releases which occurred at 7:55 a.m.
and 9:00 a.m. resulted in the following.
Release at 7:55 a.m.
Release at 9:00 a.m.
Release Rate (uCi/Sec.)
1.48 E+4 2.46 E+4 Technical Specification 8.87 E+3 8.87 E+3 Limit (uCi/sec.)
Percent of Technical 166 278 Specification Limit Total Activity
28 Released (Curies of noble gas)
A licensee representative reported as indicated above, that the instan-taneous release rate limit for noble gases was exceeded twice. A review of strip charts indicates that the limit was exceeded for a period of about four minutes in each instance.
The licensee reported that the following radio,uclides comprised the releases:
Xe-133, 72%;
Xe-135, 25%; and Xe-133m, Xe-135m, and Kr-85m, 2%.
The inspector noted that Technical Specification 2.4.3, " Specifications for Gaseous Waste Effluents", states in Section 2.4.3.1:
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"(1) The release rate liiait of noble gases from the site shall be:
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Q 94 E
+ 460 f
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iy is
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i where Qv
= release rate from all roof and unit vents in
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Ci/sec (ground release)
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= the ith individual nuclide fjy = the average gama enet gy per disintegration for nuclide i
fg = the average beta energy per disintegration for nuclide i
i Refer to Table 2.4-5 for f and f values to be itsed."
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The inspector informed the licensee representative that the instances at 7:55 a.m. and 9:00 a.m. on May 4, 1980 in which the instantaneous release rate of noble gases excceded the limit by a factor of 1.66 and 2.78, respectively, constituted two instances of noncompliance with Technical Specification 2.4.3.1.
(50-213/80 06)
The licensee's assessment of offsite reiaases also included the removal and analysis of the charcoal filter for the RMS-14 Stack Monitor to determine I-131 concentrations and activities released. The analysis indicated that, for the period covering from May 4, 1980 at 8:20 a.m.,
the I-131 concentration released was 7.14 E-12 uCi/ml and the total I-131 activity release was 26 uCi.
The licensee's (Corporate) Radiological Assessment Branch performed calculations to assess the highest offsite radiological dose.
Conservative calculations estimated a total whole body dose of 0.2 mrem for the duration of both releases at the East to Southeast site boundry (had an individual actually been present).
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d.
Onsite Exposures The licensee's Control Room Log Book indica es that on receiving the Main Stack Radiation Alarm at 7:55 a.m., an announcement to evacuate the PAB, as a precautionary measure, was made. Survey teams were then dispatched to perform surveys for contamination and airborne radioactivity levels. Access to the PAB was restricted to those teams.
The licensee representative stated that the surveys indicated that lo contamination above limits had been found in areas which had previously been non-contaminated.
The inspector reviewed the results of the licensee's air samp(at 7:55 a.m. and 9:00 a.m. ).les taken at various locations of the PAB events All of the samples, approximately nine, indicatad airborne radioactivity concentrations at less than ten percent of tne values specified in Appendix B, Table I, Column 1, of 10 CFR 20.
With regard to personnel exposure, a licensee representative stated that, at the time of the two events, there were no personnel in the PAB.
On the basis of the survey results, the licensee restored access to the PAB at about 10:00 a.m.
3.
Exit Interview The inspector met with the licensee management representatives (denoted in Paragraph 1) at the conclusion of the inspection on May 5, 1980.
The inspector summarized the scope and findings of the inspection.
The licensee representative stated that the p~ ocedure governing the sluicing of the
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r spent ion exchanger resin would be revised prior to the next sluicing evolution so that any dissolved noble gases are routed to and processed by the Waste Gas Process System.
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