Experimental studies of passive neutron measurement for fuel debris at Fukushima Daiichi Nuclear Power Plants

Nagatani, Taketeru; Shirato, Atsuhiko*; Kosuge, Yoshihiro*; Sato, Takashi*; Kawakubo, Yoko; Shiromo, Hideo; Asano, Takashi

Proceedings of INMM 56th Annual Meeting (Internet), 10 Pages, 2015/07

As one of the candidate material accountancy technologies for the fuel debris at Fukushima Daiichi Nuclear Power Plants (1F), we propose the application of a passive neutron technique. The applicability of the new concept to the fuel debris at 1F was evaluated by simulation and the results were presented at the last INMM annual meeting. As the next phase, we conducted experimental tests to confirm the validity of the simulation results. Because actual fuel debris or irradiated fuel cannot be handled at our facility due to a licensing limitation, un-irradiated MOX samples, neutron absorbers and Cf-252 sources were utilized as the best available material to imitate the property of the fuel debris and various configurations were measured using an Epithermal Neutron Multiplicity Counter. The fissile mass in the samples, neutron absorber mass surrounding the samples and intensity of Cf-252 source were varied to confirm the correlation between DDSI response and the leakage multiplication. Test results agreed well with the trend of the simulation results. This indicates that DDSI has sufficient capability to evaluate the leakage multiplication of a sample which includes an unknown amount of fissile material and neutron absorber such as the fuel debris at 1F. This paper provides experimental studies of passive neutron measurement based on the combination of DDSI technique and coincidence counting for fuel debris at 1F.

Development of prototype national nuclear forensics library at Japan Atomic Energy Agency

Kimura, Yoshiki; Shinohara, Nobuo; Funatake, Yoshio

Proceedings of INMM 56th Annual Meeting (Internet), 8 Pages, 2015/07

Addressing training needs of security and safeguards implementation officers at nuclear facilities

Vidaurre, J.; Noro, Naoko; Matsuzawa, Reina; Miyaji, Noriko

Proceedings of INMM 56th Annual Meeting (Internet), 10 Pages, 2015/07

Officers at nuclear facilities have substantial responsibilities in the management of nuclear materials: They have to assure that nuclear material is properly controlled and accounted for; they need to detect and deter unauthorized access and removal of nuclear material and protect it from an insider or an outsider threat. At the same time, they need to comply with their State's commitments on nuclear nonproliferation that uses nuclear material accountancy as a fundamental verification measure. To perform such a variety of tasks, facility officers responsible for safeguards and security require a set of Skills, Knowledge and Attitudes commensurate with their responsibilities and tasks. To address this needs, the IAEA and its Member States have conducted a series of training courses, the vast majority of which were targeted to regulatory authorities on safeguards or nuclear material accountancy topics. There are few courses dedicated to facility officers or operators addressing holistically their security and safeguards requirements. This paper analyses the evolution of training courses for authorities and facility personnel in a changing environment from nuclear nonproliferation focused-era to the current broader approach encompassing safeguards and security. Then it recalls some conceptual developments of the recent past and attempts to justify a change in direction on the focus of Member State's training. Finally, it brings some specific proposals towards strengthening and increasing security and safeguards training in Nuclear Material Accountancy and Control relevant to the tasks and responsibilities of safeguards and security practitioners at the facility level.

Conceptual proposal of new detection method for unauthorized removal from glovebox

Nakamura, Hironobu; Tanigawa, Masafumi; Mukai, Yasunobu; Nakamichi, Hideo; Umino, Yoshinori; Fujisaku, Sakae; Kimura, Takashi; Kurita, Tsutomu

Proceedings of INMM 56th Annual Meeting (Internet), 8 Pages, 2015/07

In the MOX handling facilities, many types and amount of nuclear materials (NM) that are relatively easy to access are used in a GB. In order to prevent unauthorized removal of NM from the GB by an insider, based on the Japanese regulation which was referred from INFCIRC/225 Rev.5, the 2 person rule are being introduced at the area where NM handling GB are installed. As an example of usage of the security counterplan for the detection of unauthorized removal of NM, a new proposal of detection concept for the unauthorized removal by operators were investigated with implementation of several experiments considering actual GB operation. In general, it is considered that normal concept is to use radiation monitor ( or neutron) to detect the event by checking the variation of monitoring data. However, it is thought that distinguish between authorized NM movement during operation and the unauthorized removal (sample bag-out from GB) is very difficult. To solve this subject, JAEA studied and proposes a new concept about negative pressure monitoring in the GB in addition to the radiation monitoring. It is thought that the hybrid monitoring concept between pressure and radiation provides the detection alarm for it with central alarm station (CAS) accurately and rapidly with high integrity, and helps to complement current 2 person rule.

Investigation into cause of increasing count rate on PIMS at RRP, 1; Search of potential causes

Mukai, Yasunobu; Nakamura, Hironobu; Nakamichi, Hideo; Kurita, Tsutomu; Noguchi, Yoshihiko*; Tamura, Takayuki*; Ikegame, Ko*; Shimizu, Junji*

Proceedings of INMM 56th Annual Meeting (Internet), 9 Pages, 2015/07

The PIMS used at Rokkasho Reprocessing Plant can quantify plutonium amount in each process vessel located inside glovebox by means of neutron measurement. Since the PIMS is not used for the neutron coincidence counting, it is very important to maintain that those constants meet the actual process condition. PIMS was calibrated in 2006, and then JNFL has been started to measure the Pu amount directly in each glovebox for the purpose of facility NMA. However, it was found that PIMS counting was unexpectedly and continuously increased during long time of inter-campaign. In order to find out the main cause, JAEA and JNFL jointly conducted several investigations. In the investigations, correctness of system parameters and relevant constants, behavior of the neutron generation when MOX powder is stored in actual glovebox for a long time (to see O/M and moisture change) and the behavior focused on the relation between MOX powder and light element using inside glovebox (fluorine is included in the PTFE which is used in many gloveboxes as packing of instruments) were experimentally confirmed using MOX powder in PCDF. As a result, since the same behavior happened in the actual PIMS was confirmed in the testing environment in which MOX powder coexists with fluorine, it is concluded that the main potential cause of PIMS is the increasing of the probability of (, ) reactions by a contact between PTFE and MOX powder.

Capacity building cooperation on nuclear security; Japan's experience of COE cooperation with Indonesia

Noro, Naoko; Naoi, Yosuke; Matsuzawa, Reina

Proceedings of INMM 56th Annual Meeting (Internet), 9 Pages, 2015/07

For effective human capacity building, COE collaboration is an essential factor. As Japan's COE, ISCN has expanded its capacity to provide nuclear security training and infrastructure development support with the strong support from U.S. This paper describes the methodology and contents of ISCN's human resource development cooperation with Indonesia through COEs. The purpose of this paper is to provide a model for capacity building cooperation in nuclear security by introducing Japan's experience, and thus contribute to strengthen regional as well as global nuclear security.