{"id":1700,"date":"2016-09-20T09:12:39","date_gmt":"2016-09-20T00:12:39","guid":{"rendered":"https:\/\/fdada.info\/?page_id=1700"},"modified":"2017-01-06T17:21:41","modified_gmt":"2017-01-06T08:21:41","slug":"obj_1_2-en","status":"publish","type":"page","link":"https:\/\/fdada.info\/fdada\/en\/home2\/decommissioning2\/obj_00-en\/obj_1-en\/obj_1_2-en\/","title":{"rendered":"Cooling"},"content":{"rendered":"\n
\n

Cooling<\/h1>\n

Purpose<\/h2>\n
    \n
  1. To provide cooling for fuel debris and estimate and manage the condition because there is a risk that the radioactive materials in the fuel debris are released if \n\nthe fuel debris is not sufficiently cooled and the temperature of fuel debris rises.<\/li>\n<\/ol>\n
    \n

    Current status<\/h2>\n
      \n

    1. \nTEPCO is carrying out the maintenance and management of the equipment for cooling fuel debris as well as continuous monitoring of the parameters including the \n\ntemperatures of the reactors. The buffer tanks which are the water source of the circulating injection cooling facility that cools down the fuel debris was replaced \n\nwith condensate storage tank (hereinafter referred to as \"CST\") on July 2013 and the operation of the CST reactor coolant injection system has been started. \n\nThereby,improvement of seismic resistance and increase in capacity are being achieved for the tank, reducing the risk of losing water injection function due to \n\nreduction of a reactor water discharge line length. In addition, the desalination system (RO), which is one of the circulating injection cooling facilities,was \n\ninstalled and the construction for smaller circulation loop in the T\/B of Unit 4 is being conducted. This construction will reduce the circulation loop (outdoor \n\ntransfer pipes) from approx. 3km to approx. 0.8km (approx. 2.1km if transfer line for stagnant water included).\n <\/p><\/li>\n

    2. \nAs described above, the parameters including the temperatures of the reactors indicated stable value which was lower than that immediately after the accident. Also the \n\ntemperatures in the RPV and PCV have been declined due to the continuous cooling and decrease in decay heat, and it can be estimated to be in a stable cold shutdown \n\nstate.\n <\/p><\/li>\n

    3. \nIn the implementation plan, the reactor core re-damage frequency is approx. 5.9 x 10-5 \/ year according to the risk assessment of the reactor coolant injection system \n\nby probabilistic risk assessment. It can be confirmed that the risk is reduced compared to the reactor core re-damage frequency of approx. 2.2 x 10-4 \/ year evaluated \n\nin the \u201cReport (Part 1) on facility operation plan (Revision 2) (December 2011). In addition, according to the evaluation of the reactor coolant injection system in \n\nthe event of abnormality, even in the case where the amount of radioactive materials of three plants are assumed to be released due to an event equivalent to a severe \n\naccident greatly exceeding an expected level (water injection shutdown for 12 hours), the effective doses are approx. 6.3 x 10-5 mSv \/ year at the site boundary, \n\napprox. 1.1 x 10-5 mSv \/ year at a 5 km point from the Specified Nuclear Facility, and approx. 3.6 x 10-6 mSv \/ year at a 10 km point from the Specified Nuclear \n\nFacility and therefore, it is considered that there will not be a significant risk of exposure to the general public in the vicinity.\n <\/p><\/li>\n<\/ol>\n<\/br>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"Cooling Purpose To provide cooling for fuel debris and estimate and manage the condition because there is a ri […]","protected":false},"author":1,"featured_media":0,"parent":1687,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_bbp_topic_count":0,"_bbp_reply_count":0,"_bbp_total_topic_count":0,"_bbp_total_reply_count":0,"_bbp_voice_count":0,"_bbp_anonymous_reply_count":0,"_bbp_topic_count_hidden":0,"_bbp_reply_count_hidden":0,"_bbp_forum_subforum_count":0,"footnotes":""},"class_list":["post-1700","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/pages\/1700","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/comments?post=1700"}],"version-history":[{"count":1,"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/pages\/1700\/revisions"}],"predecessor-version":[{"id":2739,"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/pages\/1700\/revisions\/2739"}],"up":[{"embeddable":true,"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/pages\/1687"}],"wp:attachment":[{"href":"https:\/\/fdada.info\/fdada\/wp-json\/wp\/v2\/media?parent=1700"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}