18
NuclearPlantJournal.com Nuclear Plant Journal, May-June 2016
Research &
Development
Excerpt of presentations at the
International Workshop on the Use of
Robotic Technologies at Nuclear Facilities
at the National Institute of Standards
Technology (NIST), in Gaithersburg,
Maryland on February 2-4, 2016.
Deployment at
Fukushima Daiichi
By Taichiro Arahata, Tokyo Electric
Power Company (TEPCO).
The discussion includes remote
operated mobile robots in missions under
extremely high radiation conditions
inside reactor buildings of Units 1, 2 and
3, which experienced core melt. Over
twenty kinds of robots have been utilized
in such missions since April 17, 2011,
when two PackBots of iRobot Co. were
used for the first time.
Lessons learned from previous
missions, information on machinery
currently under development and future
plans for robotics application are also
included. Additionally, topical changes
in Fukushima Daiichi site since March
11, 2011 are introduced with expectation
for suggestions from external parties.
Robots utilized for stabilization
operations, starting just after the accident
until cold shutdown, are introduced
first. In this phase, robots are used to
know environments inside the reactor
buildings. They took still images and
motion pictures, and measured data
such as dose rates and temperatures.
These robots performed surveys before
human operations under high radiation
conditions (> 1Sv/h) and reduced the risk
of serious troubles in the operations such
as human over exposure.
After the accident, TEPCO received
several offers from external parties
to use their robots for post-accident
stabilization and put some of them into
actual operations. Feedbacks from onsite
operations were given by TEPCO to the
offering parties for further development.
The field of robotic operation was
expanded from the first floors of reactor
buildings to basements and top floors.
These improvements made major
contributions to achievement of cold
shutdowns of the three damaged units.
The obtained knowledge is also applied
for development of robotics technologies
in the fuel debris retrieval project.
Contact: Takashi Hara, TEPCO
Washington Office, telephone: (202)
457-0790 ext.113, fax: (202) 457-0810,
email:
Narah Development
Center
By Yoshihio Tsuchida, Kuniaki Kawabata
and Shinji Kawatsuma, Japan Atomic
Energy Agency.
The Japan Atomic Energy Agency
(JAEA) is a research and development
institute of nuclear safety in Japan, and
is now building the Naraha Remote
Technology Development Center in
Naraha, Fukushima-prefecture, Japan,
for research and development of
remote controlled technology for the
decommissioning of Fukushima Daiichi
Nuclear Power Station of Tokyo Electric
Power Company. The Naraha Remote
Technology Development Center facility
is equipped with a full-scale mock-up
for equipment to repair/stop leakage in
the lower part of the PCV, and to test
apparatus for development of remote-
controlled equipment and devices. The
Naraha Remote Technology Development
Center has been in full operation since
April 2016.
Development of Standard Test
Methods (STM) for nuclear emergency
response robots is one of the research
themes of Naraha Remote Technology
Development Center. STM for response
robots are developed by the U.S.
National Institute of Standards and
Technology, and standardized by ASTM
International. STM are utilized for
evaluating, purchasing, and training with
response robots. For instance, the Fire
Department of NewYork City used STM
for purchasing robots.
For two years after the accident at
Fukushima Daiichi, more than thirty
robots have been deployed to the
Fukushima Daiichi NPS. In these, five
robots could not return; and some robots
could not complete their mission because
of troubles.
To clarify the functions and
requirements to be evaluated for
nuclear emergency response robots, it
is important to analyze the objective of
robot deployment and the reason for
the incompletion. The functions and
requirements have become clear, based
on the time analysis, and failure analysis
of nuclear emergency response robots.
From the time analysis of operation
using the Quince robot, more than
70% are moving in time, but 10% have
uncertain stops. From the failure analysis,
4 out 5 failed robots have trouble related
to communication with robot control.
Some STMs could be used to evaluate
the function and requirements. However,
additional STMs are to be developed
for nuclear emergency response and
Fukushima Daiichi decommissioning
robots. JAEA is planning to develop the
additional STM at the Naraha Remote
Technology Development Center.
Decommissioning of
Fukushima Daiichi
By Kiyoshi Oikawa, Director,
International Research Institute for
Nuclear Decommissioning (IRID).
The International Research Institute
for Nuclear Decommissioning (IRID)
is a technology research association
consisting of 18 member corporations
that focus on R&D required for
decommissioning the Fukushima Daiichi
Nuclear Power Station (NPS). We have
tied up with TEPCO’s Fukushima Daiichi
Decontamination and Decommissioning
(D&D) Engineering Company to identify
the needs of the Fukushima Daiichi
site, and are engaged in the integrated
management on the development of
various decommissioning technologies.
I will introduce some examples of
IRID’s R&D activities for preparation
of fuel debris retrieval that is a core
operation of decommissioning. Various
kinds of remote controlled equipment
and robots have been developed so far for
decontamination and investigation inside
the reactor building.
In 2012 and 2013, we investigated the
dose rate and contamination distribution
at each floor of the Units 1-3. Therefore,
the conditions inside the reactor buildings
are still very severe. We have developed
three types of remote decontamination
equipment: suction/blast type, high
pressure water jet type and dry ice blast
type.
