ML19224C046
| ML19224C046 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/07/1979 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| OLS-790507, NUDOCS 7906280196 | |
| Download: ML19224C046 (5) | |
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5/7/79 NRC STATUS REPORT ON THREE MILE ISLAND The NRC staff has comoiled the fol l owing s ta tus repor t on operations at Three Mile Island.
1, Present Plant Status Reactor decay heat is being removed bv natural circulatior: of the reactor coolant through the core and the "A" steam generator.
The "A"
steam generator is steaming to the main condenser.
The "A"
l oop cold leg primary coolant temperature is about 160F and the hot leg is about 170F.
Primary system pressure is 900 psig.
The hot tes t incore thermocouple is about 310F.
One significant measurement has been made in the plant during the past several cays and another is planned.
A measurement was made of radioactivity inside the containment building.
It indicates that the present dose level from cases within the buildire is about 100 R/hr.
Other sources of activity such as activity deposited on the containment walls and water on the reactor building floor also contribute to the dose level in containment but cannot be directly estimated at thi s t ic:e.
A neasurement of water level on the floor o' the containment buildiog will be made in the next few days to confirm calculations of water quantities that have been accumulating in the containment.
The measurement will be nade by a technique (a pressure measurement) which does not require renoval of water from the containment floor.
2.
Future Onerations at Unit 2 Operation of the reactor wi th cooling by natural circulation will continue until processing of the contaminated primary cociant water begint-This precessing will involve periodically passing a fortion of the primary coolant water through a processing facility to remove chemical and radioactive contaainants by methods such as evaporation and/or demi ne ra l i za t i on.
Temoe ra t u r es in the core will continue to decrease in proportion to the decay heat rate and primary coolant temperature.
Pressu. in the reactor will be decreased to about 500 psig, with further icductions made as plant parameters permit.
When primary coolant prous... '. ; hagins, cooling of the reactor will be accomplished bv means of a decay heat renoval system, which will be coordinated with the processing plant.
When the closed cooling system for the
'B" steam generator is complete, this system will be placed in a standby status.
The "B" steam generator system is not required now for natural circulation cooling or to remove low levels of decay heat ' rom the core.
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' An additional pressure and volume control system also will be available for operation in the near future.
The system is scheduled for comoletion in late May.
Previously planned modifications to the "A" steam generator, similar to those being made to the "B"
steam generat r,
are not being imolemented.
Such modifications are not required for the "A" steam generator to be used for the natura! circulation cooling mode.
The low radioactivity levels in the "B" steam generator will allow use of the "B" generator for an indefinite period, if required.
3.
Maior Plant Modifications (1) Auxiliarv Puildir q/ Fuel Handl ina Bu
- 1dino Fil t rat ion Svstem A system consisting of four fans and four trains of high efficiency particulate and charcoal fikters treats exhaust air from the stack.
This system provides additirnal filtration beyond the existing ventilation high efficiency particulate and charcoal filters systems, thus acting as a cockup to those sys ten.s.
Although the current iodine levels are below MDA offsite, this system provides a further significant reduction to the iodine releases.
The first portion of the systam went into operation on 5/1/79 and the remainder on 5/4/79.
(2) Liquid Waste Processino Facilities EPICOR I - EPICOR I is designed to process contaminated liquid wastes containing relatively low levels of radioactit.ity.
This system uses an ion exchange process and is currently in service.
To date, 90,000 gallons of liquid waste have been processed.
EPICOR 11 - EPICOR 11 is designed to process liquid wastes containing higher levels of radioactivity than EPICOR I, utilizing the same ion exchange process.
EPICOR 11 will process contaminated water which resulted from the accident when it becomes operational near the end of May.
These systems will provide a significant capability for ourification of contaiminated water, assuring that the processing of current wastes can proceed expeditiously.
(3) Storaae Vassel s in Fuel Pool "A"
Additional tank storage, consisting of five tanks with a combined capacity o f 110,000 gallons, is being installed in spent fuel pool "A"
The tanks will provide temporary water storage space for highly contaminated liquid waste.
Thi s tempora ry s torage is significant because it allows additional safe storage of this waste for decay and processing.
Completion is scheduled for mid-May.
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l (l ) Lono Tern Coolino Svsten for Steam Genarator
'B" i
This system consists of a pump, heat exchanger, surge tank and demineralizers.
l' will tie into existing 'B" feed and steam lines to allas solid circulation cooling through the "B"
The systen can operate at a high pressure to reduce the probability of primary to secondary leakage.
This modification is siani#icant in that it will provide a backup to the present made of heat renoval, as well as assurance that the primaty system coolant will be confined.
Completion is scheduled
'or mid-May.
(5) Pressure / Volume Control Svsten Three nitroges. pressurized surge tanks, charging water storage tanks and two charging pumps will provide a nearly passive means of controlling RCS pressure and will replace any volume lost because of leakage.
Comoletion is scheduled for the latter part of May.
(6) Unorade of Evistino Decav Heat Renoval Svstem Additional shielding of the DHR systen will allow access to the auxiliary builcing if the DHR system must be used.
Modifications have been made to make the existing equipment more leak-tight and maintenance free and to provide remote monitoring of system equipment during operation.
(7) Alternate Decav Heat Renovat Svste, An alternate to the existing DHP systen is being constructed, consistino of a skid-nounted ouno and heat exchanger.
This systen can be installed and used in preference *o the existing DHR systen if the existing systen fails to perform sat is factor ily or to avoid contamination and high radiation levels in the Auxiliary Building.
Completion of components of this system and its control t railer, which will be kept in a standby basis but not connected, is scheduled for 5/18/79.
(8) Diesel Generator Power Supolv for Ba l a nce-o f-Pl a n t Loads Two 2.5 MW diesel generators have been installed to furnish emergency power to critical systems in the event of a loss of all off-site electrical power.
Systems included are those needed for long term cooling and the exhaust filtration systems.
This emergency paver systen is scheduled to be operational on 5/10/79 (MORE) 258 086 i
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-4 4
Environmantal I n f o rma t i on The release of radioactive material into the atmosphere from Unit 2 at the Three Mile Island nuclear power plant has decreased.
NRC thermoluminescent dosimeters at 47 offsite locations have shown natural background levels of radiation for the past several weeks.
Continued plume radiation surveys, on the ground by NRC teams and in the air by Selicopter, show that levels have decreased from highs of a few tenths o' a millirem per hour in early April to essentially background levels (0. 02 mi l l i rems pe r hou r) now.
Recent air samples by NRC and by EPA have typically shown a range of less than minimum detectable &ctivity to highs of a few tenths of a picocurie per cubic meter for iodine-131.
This is consistent with the installation of fresh charcoal filters and the addition of a second, redundant filter system at the plant.
In mid-April, 30-minute air samples taken in downwind di rect ions f rom the plant by NRC ground survey teams indicated a maximum concentration of iodine-131 of 200 picocuries oer cubic meter.
Average daily concentrations have been 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 milk samples on April 29 and May 5 f rom a nea rby f a rm indicated 20 to 30 picocuries per liter.
The FDA action level for milk is 12,000 picocuries per liter.
Occasional routine liquid releases from the Unit I radioactive waste treatment system are being made to the river.
All such releases are monitored and have been less than regulator.y l iaj ts pe rmi t.
NRC estimates of the amount of radiation exposure to the population from March 2P; until April 7 i s a s fol l ows :
-- Maximum dose to an individual standing outside near the north gate for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> a day, seven days a week has been 36 millirems;
-- Average dose to an individual within a radius of 50 miles in any direction has been I 6 millirem;
-- Collective dose to entire population with a radius of 50 miles in any direction has been estimated to be 3300 person rens.
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. The amount of radiation to which an individual living in the Ha rrisburg area is exposed each year from natural background is about 120 millirems.
The natural background collective dose to which the entire popilation within a 50-mile radius of the plant is exposed each year is 200,000 person-rems.
Future operations at the facility will require movement and processing of highly contaminated water.
Release of radioactivity to the environment in excess of routine operating levels is not anticipated during these operations.
Unplanned releases of short duration are possible.
H owev e r, even for those, it is not expected that releases would exceed allmaable limits.
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