(00:00:00) It's seven o'clock and northern states power company has scheduled a press conference for 7 to discuss the incident at Prairie Island nuclear power plant near Red Wing today, Greg. Baron is standing by hopefully at NSP headquarters in Minneapolis and Greg. If you're on the line is that press conference about ready to (00:00:22) begin. Well Gary, the reporters are gathering now here at NSP headquarters in Minneapolis. The press conference will be starting in just a few moments Rowley Comstock vice president and SP has just entered the room. He's walking toward the podium now reporters are waiting expectantly. There are some Communications people here now, mr. Khan stock is asking reporters if they're ready to go and testing for volume levels as our listeners to know the background is at about 2:30 this afternoon, General emergency was declared at And as peace Prairie Island plant due to a failure of part of the steam generating system and there was a release of radioactivity. Mr. Comstock is looking expectantly around the room at this point waiting for other principles to arrive Wayne Kaplan, one of the communications people with NSP was in earlier. He had indicated that the plans at that time about 10 minutes ago indicated that perhaps there would be one or more of nsps nuclear Engineers joining. Mr. Khan stock during the during the press conference again, there's a few last-minute to consultations taking place right now. The entire Twin Cities, press Corps is here representatives of virtually all of the television newspaper and radio media. More reporters are walking into the room right now. Mr. Comstock looks just like he's about to begin. But again little more of a delay, maybe we can get a little bit more information here. No, mr. Comstock. Looks like it's about to begin. We're going to move now up to the podium where we will at this point apparently get some more details on this afternoon's General emergency at the Prairie Island Nuclear Plant. Well as we can see there's a bit more of a delay. It appears. There are other NSP officials here now and one can only presume that we're waiting for these people to join. Mr. Comstock. This press conference is taking place in nsps Auditorium, and it's nearly half filled not a large Auditorium, but there must be 30 representatives of the media. Mr. Comstock is now at the podium. And I know that you know why we've called this meeting. At 214 this afternoon at our Prairie Island plant near Red Wing the radiation monitors detected a gaseous release into the environment. That said into play a series of events some of which occurred inside the plant some of which are occurred among state governments and indeed among National agencies. Our purpose here tonight is to tell you what we know to try to tell it as fully and is completely as we can. And I think we have the appropriate people here to answer your questions and share what we know at this point. I'd like to make two basic points that I hope will come out of our discussion here tonight one is that the emergency systems worked the hardware systems work the communication networks and planning that have been set up recently by state government and ourselves and federal governments all worked. Second point I would hope that would come from this discussion. It relates to the nature of the emergency itself. The radiation that was released to the environment did not and at past North present time pose a public health threat or danger. In fact, it was so small that today. We have been able to measure or to find it with our monitors outside the plant itself to my knowledge. Neither has the Minnesota Department of Public Health. And as I speak to you NRC teams have should have by now arrived on the site and they will be conducting their their own investigation into this matter as well as the taking their own measurements. I would like to have Dennis Gilbert who is yes, I to my knowledge based on the information that I've been furnished at this point in time that the measurements taken by the health department. If not, exceeded background radiation that is normally measured if you have different information than I have. I can only share with you what I have at this point in time. My concern is how many measurements that you made those types of things because I just talked to help businesses emergency room. I think that the gentleman and trying to introduce Dennis Gilbert's from manager of our production facility can give you the most up-to-date information about what has been going on at the plant site understandably. The plant operators are at the plant site dealing with the matter and necessarily at this point in time. We can only share with you what we know here Dennis. Introduce yourself and your title. Yes, my name is Dennis Gilbert and I'm the general manager of power production for northern states Power Company. And I would like to give you some information on the occurrence as we note at this time. We've been in contact with the plant and have the general outlines of it. We do not have a lot of data. I purposely avoided burdening the plant with a need of need to have a lot of communication to to us here in general office until such time as they have their facts in order and the situation is all well under the troll. So what I'm saying to you is on the basis of information that we have now in the general outlines of it. I'm sure we'll have more detailed information for you perhaps tomorrow. just can you hear it by? That's not good. Can I turn this a bit I can point to it? Okay. I'll try to don't push it too close to all your I won't be able to see it. Okay. This is a very schematic chart of the reactor system at Prairie Island. And just let me walk you through it briefly. This is the reactor itself. In which water is heated by means of the nuclear reaction. The water is the heat is removed by water flowing through the protocol the primary Loop to a steam generator where it is cooled returns through a pump and is recirculated again through this system. The steam generator is a vessel in which feed water is pumped around the tubing this is like I say very schematic in actuality this consists of a large number of small diameter tube. So inch in diameter approximately No, this constitutes a primary barrier between the coolant which circulates around the fuel rods and the the secondary system. The water which circulates in the reactor becomes somewhat radioactive during its during the operation. That's why we have this barrier in the between the two systems. Out of continuing normal normal operation the steam from the steam generator is led into the turbine room. It passes through the turbine and which it converts the heat energy of heat and energy of motion. The generator Drive the turbine drives the generator. Of course, the water is condensed in a condenser, which is again another closed vessel of many small tubes, which river water is circulated to cool this water to back to or the steam back to Water Works recirculated into the steam generator. No, apparently what we have here is a rupture in one or more of these tubes in steam generators self, which as this pressure is higher than in the in the secondary system causes primary coolant to pass into the secondary system passes into the steam generator is condensed and recirculated the liquids are contained and so forth, but there are certain dissolved gases which are carried over with the Steam and the are in leakage along seals. And so forth must be removed from a turbine through a system that called are ejector which vents the atmosphere and it's shown schematically as a vent. There is actually some equipment in between that All right, that's basically the system now what apparently is happened at Barry Allen is that we've developed a tube rupture of a fairly large magnitude. The steam generators, there's been a history of some leakage in these but they were generally small leaks that are picked up and then the tubes are are removed from service by plugging in this case. It appears. We've got a fairly large rupture probably a tubes. But as our guest right now some length, which allowed a fairly large amount of primary water to leak into the secondary system. And again, it carries some radioactive gases along with it. The system is is set up so that when radioactivity is detected at the air injector vent, which is shown here is that yellow arrow that the the indication radioactivity there is used as an indicator of a leak in the steam generator well now to get down to the chronology of what happened very Allen at 2:14 this afternoon, they they started to get indications from this radiation detector on the off gas vent that there was a radioactive gas use release being made at that point. at at 224 the the leak apparently increased to such a magnitude in here that the pressure level in this primary system fell to the point at which the automatic systems were activated to shut down the reactor shut down the turbine initiate some automatic systems to assure water flow into the OR continued water supply to the to the reactor all of these systems work as designed quite properly. the the operators in recovering from the shutdown of the reactor immediately begin their analysis of what was going on and they were able to pinpoint the cause of the problem is the number what they call the number 11 steam generator. There's two of them ones called number 11. It is number 12 as being the source of the problem. There are valves in this line, which were then isolated stopping the flow of primary coolant into the secondary system. So 241 that that flows terminated. At 2:30 the site emergency director called a general emergency because of the release of radioactivity through a in an unplanned manner through a to the radio through the air ejector vent pipe. This sets the motion certain events, which have transpired since they immediately notify the NRC the State Department emergency services State Health Department's of Wisconsin and Minnesota and they'd immediately dispatch radiation monitoring teams to the environment around the plant to measure any levels of radioactivity that might be occurring off site. This was done the reports that we received to date from the client indicated not find found any radioactivity external to the plant from the by our monitoring Cruise. The state has people in the area the first reports that I've had in that they had not found anything either. Maybe there's later information that is available that I'm not aware of but He was the source of she was the first not downtown Dallas is they have just checked with Minnesota Health Department. And the health department is still saying that they have found no radiation levels above background levels at this point near the plant earlier a reporter with one of the newspapers at challenge. Mr. Comstock indicating that he had been told that the health department had found background levels levels of radiation higher than the background back to this. Podium satisfy shortly What caused the leak that will have to be determined after we get in there? Our next procedure will be to continue the shut down the reactor to us in the cold State and then we open this the access to this steam generator and we we use a system of scanning the tubes to see if there's a defect and what effect it is and will be able to tell from that as to what what might be the cause. Billy Cause itself. No, we do not know what this time. No, you wouldn't know until you look if any failure analysis would requiring that look at and current problems with leakage on steam generators. And these have been a this has been a two types primarily one is a pitting type corrosion second type of what they referred to as denting which is a support place that that space these tubes keep them in an alignment and corrosion products in some you have built up there squeeze the tube until it's it's be formed and has failed our reactors. We periodically check. To see if we're having either one of these phenomena occurring and to date we've not detected either these phenomena taking place. Yes, I suppose there could be I suppose it could range all the way from a an original tube that was weak. For some reason to some other type of mechanism that we're not having been identified yet. With the present state that is shutdown. Is there any possibility whatsoever situation progressing in any way in the reactor at least in general? This is a you need a lot of pressure across there too to cause a a open opening of a large failure. No, I don't lie to this type or tube leaks and these things you go in locate the wiki tube and then plug it and then you sample the rest of the tube to see if you got a similar or something something going on there that that would indicate week tubes and you would plug any other weaknesses. That'd be my kind of a guess I would. At this time, it's not particularly serious because of the load is low this time of year. We were able to make it up with other generation that we had on a system coal-burning generation and some purchases. No, not of any accessory. No. I don't have any numbers, but I wouldn't expect to be miserable. Even on the side he would not expect expected to be the measure of not certainly not within levels that are unusual for in tonic workers. What would that be the quarterly dose? Limits are 15m our reporter like director hard Yes, 15m our report another reporter for three-month Port area and we I don't think it'll be different from what they normally a day-to-day type of exposure for the vast number of people there know maybe some people Engage The sampling or something might've been different than the supposed to do. Exposure you have for the people that know I haven't I haven't got any numbers on that. But it if it was they would have certainly don't point that out. Oh, yes. Yes. Yes sure. We'll have it the morning. It well, I'm sure it would be available. I seems to me it would be oh they do at the plant. I personally don't know though. I'm saying I didn't inquire and that it's if it would have hit their be if there have been any exposure that certainly the one of the things that have been reported to the they declared a state of emergency which is different than a general emergency. In that period shortly after General mergency was was declared a state of emergency just has all you people that aren't immediately involved in the operation of plant you assemble that a couple of days pre-designated points outside the plant and it's just to get people out of the area. So they want to keep track of them or in this case. It was for there's other causes. Well, it'd be all with the operating Crews and Technical people that were assisting them. Well. This is on the day shift your maintenance people that have been there in your office people 60 on the order of a hundred. I would say would have been assembled in the what remainders. Right now the total number of people who mean on shift. I guess it's 50 left, you know and engage not races. That's really true - yes. Yes. Since this has happened. I am not aware of any but it we've been you know in constant dialogue with the community for since before the plant was built. It's they are considered just like any other group within certain levels and would be evacuated under certain. I can't answer that for you know out of my own knowledge. I would doubt that they would be until a level was established at said yes, there was an emergency all site as far as I know. That is correct. And that's the one that decides whether that should be permitted. Once they're on the general emergency means that there is a release of radioactivity which might affect areas off the site. And it's affecting the public and this is what triggers the general emergency consideration. Still in effect until those healthy purposes now, there's nothing here. Just just the the area involved is he? Well, it's a ten mile radius is kind of well, it is three mile radius is the is the area of primary concern and there's a secondary concern further out you so you don't check in close and then move out his At other plants we have not detected it. There have been a couple of other instances where that we're aware of that there have been a large enough leaky or passage of water from the primary and secondary system that they've had a significant released. So The mechanisms of the corrosion problem our object of intensive study and really haven't been entirely identified there seems to be a preponderance of saltwater Flats with this has been a difficult in other words using ocean water for cooling but the chlorides in the ocean water of the in leakage from the penitentiary water has a solution that's Prairie island has been no to bug the number one. We plug 1 and number 2 in (00:26:23) 1977 the mechanisms of the corrosion problem our object of intensive study and really haven't been entirely identified there seems to be a preponderance of saltwater plans for this has been a difficult other words using the ocean water for cooling, but the chlorides in the ocean water of the in leakage. Hence, our water has that's Prairie island has been know to bug the number one. We plug 1 and number 2 in 1977. It's identical to the one but the history of it has been very distant. Very good. Welcome. It's been very tight. We haven't had the problems because I'm saying is there's a problem in the industry that has been. well, the primary ones that we be of concern are the gaseous ones not being a nuclear physicist. I hesitate to Rattle them off but they're typically the noble gases are they are the ones that are There have been very low levels of iodine in our primary coolant down there so they would not be significant amounts coming across the levels. I can't. They going to work on happen. Yeah, and so am I I'm not really qualified to speak to the protection. No, we really don't there at the plant site and I guess we'll have to depend on them. Yes. Yes, I would say that it is the only one word ever. We've ever had a general emergency called. That's I think a fair statement is not correct system is under control what they're doing the protection people and they were still in contact with them. They will run on down to this area check this and I said, well I said, I think I got the general picture. Yes, it's on. Well be the first indications I said was it to 14 and the isolation was completed to 41. This is primary water to water it circulates through the reactor. Yes, I think that's great. Automatically shut down the still maybe I don't, you know have a detailed answer for that because I'm not really been able to. Discuss that extent I suspect what they were doing is trying to analyze where the problem was isolated what 27 actually actually from the primary to the secondary the past there was a leakage path. Okay unit one started in 1973 and number 2 1974 remaining they should still be detectable, but it would have the short real shortly after Isis yes or no, some people gateways again fine. It would be a very the quantities are very Manute they all were talking about and if there were short half-lives beside the chances of that occurring I would think would be very very small. The vent was up to the roof to the atmosphere. That's right. The plant but they would have checked in. No, the only only in the plant you would get there are certain drains and such off steam systems. That would also be carrying some of it and that would come off in the various tanks are so forces. It'll be an integrated dose over that time. That's the way they measured and I want much it's accumulated Shadow baby require being read by an instrument that is done on a periodic basis when this isn't something that for you and certainly I'm sure it'll be my things will be gone. I'm frame is you know a short period I know exactly when it will be it takes some time to eat. The radiation levels within their I can't speak to why they shouldn't be very high. So I don't anticipate any particular delay in getting in there. I would think within you know a couple of days it should be We can generate or under higher-than-normal radiational inside the steam generator won't they have such problems in a second? They really think energy is always are quite radioactive and that that gas is or that fluid is always there. So there's no real change there. No, that is that is normally a really like the area. Cosmic rays raised from the raw materials in the science of that's the information I have had. That the people here are going with for an SP that that that you're saying that the state has had. No reading. No measurable reading Beyond background. No, the question was as to what the State Health Department told you as to their results of their monitoring at the most recent time you talked to and when was that is me when she just take a second which way I've been down at the Emergency Operations headquarters. Capital all afternoon. My name is Bill Frederick. I'm in the environmental regulatory activities department for the company. My primary function is working with the state agencies and liaison work concerning our emergency plans. I spent the afternoon with Alice dolezal who is their Chief radiation officer in the health department and I sat there while they got reports from the field and reports in the field kept coming in at .012 0.1 milligrams per hour and everyone there deduce that those levels were the kind of normal levels that you would measure in any field that you were measuring instruments in measuring know they consider that as ambient levels. They did not consider any of those readings as above background levels .01 20.1 milligrams per hour. Yes outside the plant area from from three miles to two miles in right into the plant perimeter. That was background radiation measurement and the anticipated that they could find no higher level since they come so close to the plant and they were in the process of making other other searches, but that level is so low that it's barely detectable on their instrument. I think that I should have one of the health physicists in the room. The State Health Department technicians who who are trained to respond to incidents like this. They went out to a distance of three miles and then began working their way in but they went down wind in their initial searches. That was it's very important. No, the health department monitoring began when the teams were able to arrive there from from st. Paul. I do not know I do not have the values that are there in its be monitoring teams began immediately at the time of the incident. I have. No I don't I'm not aware of any of those results. Well, what really happened we were in the position where we were selling a good bit of power and we just cancel the sales is what we did. We also were able to buy some additional Hydro power from Manitoba and some from the Bureau of Reclamation old named Department of energy in over the Missouri dams. Yes, it will depending on the outage not the nuclear plants are cheaper certainly to operate and any other alternative so there will be some but it's fairly modest at this particular time of year. Oh, the the daily cost of generation of it's around 90,000 dollars a day on a nuclear plant this time of year that varies from day to day and days a week for the one unit. Yes. increase cost $90,000 Yes, that's containing copper know it takes an hour to get an hour and 15 minutes. Well, there there's a normal distribution of these isotopes that you know, what normally is in the gases. You can measure the long-lived ones that work back to what the short lives one is worse a very clear-cut statistical calculation. So that should be no particular problem that that you can tell at any given time what they were by back calculating based on what your measurements were. Is there any direct threat to the reactor core? And is there any conceivable? No, I don't think that you could characterize as a threat to the core the automatic safety systems initiated again as happens during any abnormal Transit and they worked as designed. So water was never know in a precarious condition in the core or anything of that type. So I would say no, that's fully understand. Yes. It's moving towards know. There was a loss of primary cooling water which is initiated the the activation of the automatic systems emergency core cooling system was one of them. Yes. Yes. No, we've had a number of instances mainly due to malfunction instrumentation or something that that caused this to happen in a conservative direction that that I haven't any (00:42:00) idea. Even listening to live coverage of a press conference from northern states power company headquarters in Minneapolis, the press conference regarding today's incident at the nsps Prairie Island Nuclear Generating plant in Red Wing, which of course is just about 40 miles south of the Twin City area officials saying that radioactive steam was released into the atmosphere for possibly up to 27 minutes today. When a steam to be ruptured in a generator at the plant in Sp Engineers first detected the leak at 2:14 this afternoon in one of the two 520 megawatt nuclear generators at perak Prairie Island generator was shut down ten minutes later and a general emergency was declared at The Plant 16 minutes after the leak was detected Greg you have been at the press conference and any any summary statements and he impressions of what you've seen over at MSP headquarters. Well, apparently Greg Baron has is not with us right now. The NSP officials say the situation is under control. And while the there was a release of radioactivity officials say that the health department inspectors have not been able to find any detectable radiation in the air outside the plant so again, there was an accident of apparently a steam tube rupturing at the Prairie Island Nuclear Generating plant in Red Wing this afternoon, a general emergency was declared at The Plant 16 minutes after the leak was detected plant Personnel were then evacuated and while some radioactive steam or gases rather were released some of them into the environment Health Department inspectors have been able to find no detectable radiation in the air outside the plant