ML19289G084
| ML19289G084 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/05/1979 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| OLS-790505, NUDOCS 7906260245 | |
| Download: ML19289G084 (6) | |
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NRC STATUS PEPORT ON THREE MIT.E ISLAND
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The NRC staff has compiled the following scatus report on operations at Three Mile Island.
1.
Present Plant Status The "A" loop cold leg primary coolant temperature is about 160F and the hot leb is about 170F, Primary system pressure is 900 psig.
The hotest in[ core thernoccuple is about 320F.
Two significant measurements have been made in the plant during the past several days.
A water level measurement was =ade which indicated that about gallons of water is in the reactor building. This is consistent with calculations of water inventer'es that have been accumulating in the containment.
A measurement rada'ca r f/N/
was made of
~ ~ M inside of the centainment building which int.icates
. hat the present [ac=ec.y level is 2.
Future Operations at Unit 2 Operation of the reactor with cooling by natural circulation will continue until processing of the contaminated primary coclant water begins.
This processing will involve periodically passing a portion of the primary I
coolant water through a processing facility to remove chemical and radio-active centaminants by methods such as evaporation and/or demineralization.
Temperatures in the core will continue to decrease in proportion to t'.2 decay heat rate and prinary coolant temperature.
Pressure in the reactor will be decreased to about S00 psia, with further reductions made as plant parameters permit.
When primary coolant processing begins, cooling of the reactor will be accomplished by means of a decay heat removal system which will be coordinated with the processing plant.
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When the closed cooling system for the "B" steam generator is complete, this system will be placed in a standby status.
The "B " s te am generator system is not required now for natural circulation cooling or to remote low levels of decay heat from the core.
An additional process and volume control system also will be available for operation in t'ae near future.
The schedule for co=pletion of this system is outlined in this report.
Modifications to the "A" sceam generator have not been implemented.
Such modifications ara not required for the "A" steam generator to be used for the natural circulation cooling mode and primary to secondary coolant j
leasage has not been detected nor is it expected.
3.
Major Plant Modifications (1) Auxiliarv Building / Fuel Handling Buildine Filtration Svstem A system consisting of four f ans and four trains of high ef ficiency particulate and charcoal filters takes exhaust air from the Auxiliary Building vent stack which has already passed through high efficiency and charcoal filters.
This system provides additional filtration beycnd the existing ventilatien cleanup systems, thus acting as a backup to those systems.
Although the current iodine levels are below MDA offsite, this system provides a further significant reduction to the iodine lsh rele as e s.
The first portion of the system went 4wx operation on 5/1/79 and theremainder{F:r-tijhon5/4/79.
(2) Licuid Waste Processing Facilities EPICOR I - EPICOR I is designed to process contaminated liquid wastes containing relatively low levels of radioactivity.
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_3-system uses an ion exchange process and is currently in service. To date, 90,000 gallons of liquid waste have been processed.
EPICOR II - EPICOR II is designed to process liquid wastes containing higher levels of radioactivity than EPICOR I, utilizing the df same ion exchange process. EPICOR II is 3csigncd tc process the u L'l (H dm e s /
contaminatedwatershadresultedfromtheaccidentwhenjoperationalnear the end of May.
These systems will provide a significant capability for purification of contaninated water assuring that the processing of current j
wastes can proceed expeditiously.
(3) Storage vessals in Fuel Pool "A" Additional tank storage consisting of five tanks with a co=bined capacity of 110,000 gallons is being installed in spent fuel pool "A".
The tanks will provide temporary water storage space for high-level liquid waste. This additional storage is significant because it allows additional safe storage of high-level waste for decay and processing.
Completion is scheduled for mid-May.
(4) Long Term CoolinR Svsten for Steam Generator "B" This system consists of a pump, heat exchanger, surge tank and demineralizers.
It will tie into existing '9B" feed and steam lines to allow solid circulatica cooling through the "B" steam generator.
The system can operate at a high pressure to avoid the possibility of a primary to secondary leakege=, This modification is significant in that it will provide a t ackup to the present mode of heat removal as well as assurance j
that primary system coolant will be confined. Completion is scheduled for mid-May.
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(5) Pressure / Volume Control System Three nitrogen-pressurized surge tanks, a charging water storage tank and two charging pumps will provide a nearly passive means to control RCS pressure and to replace any volume lost due to leakage.
Completion is scheduled for the latter part of May.
(6)_Uggrade of Existing Decay Heat Removal System Additional shielding of the DHR system will allow access to the Auxiliary Building if the DRR must be used.
Modifications will be made to make the existing equinment more leak-tight and maintenance free and to provide remote monitoring of system equipment during operation.
These modificaticas are essentially complete.
(7) Alternate Decay Heat Removal System An alternate to the existir g DRR system is being ccnstructed, consisting of a skid-mounted pump and heat exch ange r.
This system can be used in preference to the existing DER system if the existing system fails to perform satisfactorily or to avoid contamination and high radiation levels in the Auxiliary Building.
Completion of this unit and //s centrol trailer, which vill be kept in a standby basis but not connected, is scheduled for 5/18/79.
(8) Diesel Generator Supoly for Balance-of-Plant Loads Two 2.5 MW cicrel ganerators have been installed to furnish emergency power to critical systems in the event of a loss of off-site electrical power.
Systems included are those needed for long term cooling and the exhaust filtration systems.
This system is scheduled to be operational on 5/10/79.
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Environmental Infomation The release of radioactive material inte the atmosphere from Unit 2 at the Three Mile Island nuclear power plant has decreased. NRC ther=olu=inescent dosimeters at 47 offsite locations have shown natural background levels of radiation for the past several days.
Continued plume radiation surveys, on the ground by NRC teams and in the air by
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helicopter, shew that levels have decreased from highs of a few tenths of a millirem per hour fn early April to essentially background levels (0.02 millirems per hour) now.
Recent air samples by NRC and by EPA have typically been less than mini =un detectable activity *o highs of a few tenths of a picoeurie per c; ic meter for Iodine-131. This is consistent with the installation of new charcoal filters and the addition of a second, redundant filter system at the plant.
In mid-April, 30 minute air samples taken in down wind directions from the plant by NRC ground survey teams indicated a maximum concentration of Iodine-131 of 200 picocuries per cubic meter.
Average daily concentrations were less than 10 picocuries per cubic meter.
NRC, State of Pennsylvania, EPA and Metropolitan Edison analyses of cows milk samples have generally indicated less than minimum detectable activity of Iodine-131. Goat ctilk samples on April 29 and May 5 from a nearby farm indicated 20 to 30 picoeuries per liter.
The FDA action level for milk is 12,000 picoeuries per liter.
Occasional routine liquid releases frau; the Unit I radioactive waste treataent system are being made to the river. All such releases I'
are monitored and have been less than regulatory limits permit.
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-d-The latest Committee report from the Ad Hoc Interag;ncy Assessme-.t Group (NRC, EPA, and HEW-CDC and FDA) is expected to be released this week.
It will contain the latest estimates of population dose, individual dose, and health effects. The NRC reference nu=ber for this document is NUREG-0558.
NRC estimates of the a=ount of radiation exposure to the population from March 28 until April 7 is as follcws:
-- Maximur 'cse to an int'ividual standing outside near the north gate for 2-surs a day, seven days a week - 86 millirems.
-- Average dose tc an individual within a radius of 50 miles in any direction - 1.6 millirem.
-- Collective dose to entire population within a radius of 50 miles in any direction - Highest estimate: 5380 person rems.
- Best estimate: 3300 person re=s.
- Lowest estimate: 1800 persen rems.
The amount of radiation to which an individual living in the Harrisburg area is exposed each year from natural background is about 120 millireus.
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The] background collective dose to which the entire population within a 50-mile radius of the plant is exposed each year is 200,000 person re=s.
Future operations at the facility will require movement and processing cf this highly conta=inated water.
Release of radioactivity to the environment is not anticipated during these operations.
Unplanned release of short duratica are possible. However, it is not expected that any such events will cause releases which would exceed allowable limits.
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