Please find Fukushima Daiichi NPS updates below.
(1) Plant Status
(2) Opening of the Airlock of Unit 1 Reactor Building
ü Minor amount of radioactive airborne was released and no impact on the monitoring post.
(3) Nuclide Analysis for Unit 4 Spent Fuel Pool
ü No indication of significant fuel damage.
(4) Detection of Strontium 89/90 in the Coast/Offshore, air and soil of Fukushima Daiichi
ü No Sr-89/90 detected from the air at West gate of the site
ü Sr-89/90 were detected from the seawater neat the site and the soil in the site. We believe these Sr-89/90 come from the reactors.
Contacts:
TEPCO Washington Office: 202-457-0790
Kenji Matsuo, Director and General Manager
Yuichi Nagano, Deputy General Manager,
Masayuki Yamamoto, Manager, Nuclear Power Programs
(1) Plant Status
【Unit 1】 Injecting fresh water: 8.0 m3/h
Reactor pressure vessel temperature:
At 11:00am, May 9th, 116.6 ℃
At 10:01 am on May 6th, in order to make nuclear reactor flooded to the top of Fuel range, we have increased the amount of injecting freshwater from approximately 6 m 3/h to approximately 8m 3/h.
【Unit 2】 Injecting fresh water: 7.0 m3/h
Reactor pressure vessel temperature:
At 11:00am, May 9th, 115.6 ℃
【Unit 3】 Injecting fresh water: 9.0 m3/h
Reactor pressure vessel temperature:
At 11:00am, May 9th, 154.3 ℃
- At 10:09 am, on May 4th, we changed the amount of injecting freshwater to the reactor pressure vessel of Unit 3 from 7.0 m 3/h to 9.0m 3/h. Temperature change is being monitored.
ü May 8th
【Unit 3】 From 12:10 to 14:10 fresh water injection through the fuel pool cooling and filtering system of Unit 3 (approx 60t).
ü May 9th
【Unit 3】 From 12:14 to 15:00, 80 ton of fresh water was injected through the fuel pool cooling and filtering system. (From 12:39 to 14:36, hydrazine will also be injected)
【Unit 4】 Spraying 100 ton of fresh water was injected using the concrete pumping vehicle. (From 16:11 to 18:38, hydrazine will also be injected)
- On May 8th, We commenced preparation work for installing support structure into the bottom of fuel spent pool of reactor building at Unit 4.
(2) Improvement of Working Environment inside the Reactor Building and Opening of the Airlock of Unit 1 Reactor Building
At the reactor building of Unit 1, we are planning to install and calibrate a new reactor water level gauge and establish an alternative circulating cooling system to achieve cold shutdown condition. In order to effectively implement these works, it is essential to improve the working environment inside the reactor building, namely reducing airborne radioactive materials and dose to workers.
Based on this recognition, we have installed an ambient air filtration system on May 5th , then circulated air inside the reactor building, and removed radioactive substances with the filter and lowered density of radioactive airborne. The result showed the impact of the opening the airlock would not affect the current airborne radioactivity level at monitoring posts on the site boundary.
After air filtration and circulation in the reactor building, total density estimated as 4.8 Becquerel/cm3 based on the measured data on April 26th decreased to 1.97 X 10-2 Becquerel/ cm3, estimated based on the data taken at 3:15 on May 7th. Thus, sufficient decrease in density was confirmed and we opened the airlock from 8 pm on May 8th. (First, we removed the ducts of the ambient filtration system set at the airlock to avoid sudden change of ambient air inside the reactor building.)
Before opening the airlock, we have monitored the density of the radioactive substances in the reactor building and confirmed that the influence to the outside is negligible.
On opening the airlock, we will closely monitor and announce the values at monitoring posts.
At 4:15 am, May 9th, 7 TEPCO employees, 2 NISA inspectors and 21 contractors entered into the reactor building to start measuring the radioactive density for the further construction work.
We plan to start working for water level calibration and additional level indicator installation from the afternoon of May 10.
TEPCO has been observing the water level of the spent fuel pool of Unit 4 since April 22nd by measuring the temperature of the pool. In the course of the observation, we collected 280ml pool water on May 7th as we did on April 28th and analyzed the sample.
Nuclide | ［Half Life］ | May 9 | April 29 | April 13 | March 4 | (Reference) Turbine Building Water Puddle sampled on March 27 |
Density（Bq/cm3） | ||||||
Cs- 134 | Approx, 2 year | 56 | 49 | 88 | ND | 3.1×106 |
Cs-137 | Approx. 30 year | 67 | 55 | 93 | 0.13 | 3.0×106 |
I- 131 | Approx. 8 days | 16 | 27 | 220 | ND | 1.3×107 |
[Comment]
- We think the result of this time is consistent with previous result analyzed on April 29 considering the half lives and pool water level.
- We assume the integrity of the fuel and the pool is maintained as a whole.
- I-131 decayed about 1/2 since last time and considering the pool water inventory decrease about 0.94 times (water level changed from 6.3m to 5.9m): 27 x (1/2: Decay) x (1/0.94: Pool) = 14.4 ßà 16 Bq/cm3
- Cs-134,137 increased mainly by water inventory decrease.
Cs-134: 49 x (1/0.94) = 52.1 ßà 56 Bq/cm3
Cs-137: 55 x (1/0.94) = 58.5 ßà 67 Bq/cm3
(4) Detection of Strontium 89/90 in the seawater, air and soil of Fukushima Daiichi
TEPCO analyzed samples taken from seawater (coast/ off-shore), air and soil at Fukushima Daiichi NPS and detected strontium 89 and 90 from the seawater and the soil.
(a) Seawater (coast/off-shore)
[Comment]
We assume that Sr-89 and 90 were detected at the coast and offshore due to the accident.
But the results indicated they are below density limit of the Ministerial Notification of the Reactor Regulation.
(b) Air
- Sampling spot：West gate of Fukushima Daiichi Nuclear Power Station
（Unit：mBq/m3）
Type of sampling | Date of sampling | Sr-89 | Sr-90 |
Volatile | April 18 | N.D. | N.D. |
Particle | N.D. | N.D. |
[Comment]
Sr-89 and Sr-90 were not detected from the sample analyzed this time.
(c) Soil
（Unit：Bq/kg･Dry soil）
Sampling spot ( ): Distance from the stack of Unit 1 and 2 | Date of sampling/ Analyses organization | Sr-89 | Sr-90 |
(1)Site Field(west-northwest approx. 500m) | April 18 / Japan Chemical Analysis Center | （2.9±0.01）×10３ | （4.0±0.05）×102 |
(2)Forest of wild birds(west approx. 500m) | （2.3±0.12）×101 | （3.4±0.49）×10０ | |
(3)Adjacent to industrial waste disposal facility(south-southwest approx.500m) | （4.4±0.02）×103 | （5.7±0.06）×102 | |
Range of measured figure in the past(Ref.) | － | ND～4.3 | |
(Ref.) From the Report of Measurement Result of Environmental Radioactivity near Nuclear Power Station in 2009（1999～2008）
[Comment]
The density of Sr-90, which were detected at (1) Site field and (3) Adjacent to the industrial waste disposal facility is high compared with the fallout, which were observed in Japan in the past nuclear test in the atmosphere. It is conceivable that it is due to the accident caused this time.
- TEPCO English website
- METI(Ministry of Economy Trade and Industry)
- NISA(Nuclear and Industrial Safety Agency) http://www.nisa.
- JAIF(Japan Atomic Industrial Forum Inc.)
- FEPC(The Federation of Electric Power Companies of Japan)
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