Skip to main content

With the passing of the 30th anniversary of the incident that occurred at Three Mile Island happening last week, there has been plenty of discussion on DKos about the pros and cons of nuclear power.  Many of the opponents of nuclear power use the Three Mile Island incident as a reason why we should not pursue nuclear power in the future.  They bring all kinds of "facts" and information with their argument, much of which is fragmented and in some cases does not make any sense at all.  I really don’t care if you are pro-nuclear or not.  Objectivity and logical reasoning is what I am trying to promote with this information.  This diary is presenting the factual record of what actually happened at TMI 30 years ago.  Take from it what you will, but know that it really was the perfect storm of errors in design and operation, all coming together in 16 hours.

Unit 2 at 98% Power – still on its very first core

As usual many alarms are locked in.   The Pressurizer PORV (power operated relief valve) discharge line shows elevated temperature because the PORV is leaking as it has been for months.  Procedures require the PORV block valve to be shut in this condition, but that would put them in a Technical Specification (TS) Action Statement, so the block valve is kept open (Note: TS also required PORV to be operable).

2 Reactor Operators (RO), 1 Shift Supervisor (a Senior Reactor Operator (SRO)) on Control Room duty

The General Watch Foreman (SRO) & 2 Plant Operators are fluffing a condensate polisher bed with instrument/station compressed air and high pressure water in preparation for transfer of the resin after regeneration.  This is a normal, routine evolution.

A check valve in the air line hangs open – water enters the instrument air system lines.

HH:MM:SS Occurrence
00:00:00 With water in the instrument air lines, ALL Condensate Polisher Beds immediately isolate, stopping all condensate flow. Condensate flow drops to zero, Condensate Booster Pumps Trip, Main Feedwater Pumps Trip, Main Turbine Trips, Integrated Control System starts reducing Reactor Power.

00:00:00 Auxiliary Feedwater (AFW) pumps start but do not feed.  With Reactor Coolant Pumps (RCP) running they are designed to start feeding as soon as Steam Generator (S/G) level drops to 30 inches.

00:00:03 Reactor Coolant System (RCS) pressure reaches 2255, Pressurizer (Pzr) PORVs open to relieve pressure.

00:00:08 RCS pressure reaches 2355, Reactor auto trip (control rods inserted to stop fission)

00:00:12 Pzr level decreasing as S/G’s remove heat from reactor,  -  letdown (normal coolant discharge) isolates.  Unable to start second Safety Injection/Centrifugal Charging Pump (SI/CCP) due to RO start error.

00:00:13 RCS pressure down to 2205, auto close signal gives Pzr PORV close green light (but the PORV does not close)  This valve position indication was controlled by demand only, not by actual valve position.  There are no other PORV position indicator devices, other than tail pipe & Pzr Relief Tank(PRT) temperature, & PRT level (the PRT info is in the back of the Control Room)
The Pressurizer PORV is dumping mass equivalent to 200 gpm into PRT.

00:00:28 S/G level reaches 30 inches, AFW Feed Regulating valves open but AFW Outside Containment Isolation Valves (OCIV) are closed.
This is a prohibited condition at power left over from an un-restored start up test alignment. S/G levels continue to decrease.

00:00:30 High Pzr PORV Outlet Temperature alarm received (just one more of many alarms already in )

00:00:40 S/G low level alarms received. (This is a normal & expected alarm after Rx trip from high power due to low water inventory in this S/G design).  The S/Gs are still removing the decay heat from the core & RCS volume is decreasing.

00:00:41 With Pzr level down to 158 inches, the RO gets a good start on a second (of 3) SI/CCPs.

00:01:45 Both S/Gs boil dry, (the main core decay heat sink is now no longer functioning).  The decay heat removal path is now feed & bleed through the Pzr PORV (this is not recognized & indicators for this are in the back of the control room)

00:02:02   With the stuck open PORV removing energy from the Pzr, primary system pressure decreases to 1640 where Auto Safety Injection (SI) on low RCS pressure occurs.  The "C" SI/CCP starts & aligns to SI path, the "B" SI/CCP pump receives an auto stop signal per design. The combined SI/CCPs are capable of overpressurizing the RCS, so pump start combinations are designed to mitigate that.

00:03:13 With rising Pzr level the operators depress the ESF Actuation override/bypass button to allow throttling of SI flow in order to prevent going water solid.  (as they were trained to do) Initial SI flow was 600gpm, throttled back to maintain Pzr level, flow reduced to as low as 25gpm.  The hottest spot in the RCS was no longer the Pzr, it was now the reactor core, where saturation conditions now existed.  The steam bubble in the core was pushing water into the pressurizer.  Operators do not recognize that the rate of PZR level increase is greater than the 600 gpm SI/CCP flow capability.

00:03:26   Reactor Coolant Drain Tank (RCDT) high Temperature alarm received

00:04:00 Rapid steam bubble formation begins in the core, rapidly displacing water from the core into the Pzr.   Recognition hampered by no Reactor Vessel Water Level System (did not exist at the time) and no subcooling/superheat indicators in the primary system (also did not exist).  RCS Pressure continues to decrease.  Procedure "Loss of Reactor Coolant/Reactor System Pressure" was NOT entered. Procedure would have required SI/CCP pumps & RCP flow to remain on until normal RCS pressure was returned.

00:05:00 RCS pressure continues to decrease, shows 1340 psig, with hot leg temperature of 582°F.  Boiling starts to occur in the loops, displacing even more water through the stuck open PORV.

00:06:00       S/Gs are completely dry, operators do not notice, their attention is focused on actions to get condensers and condensate back in service so they can use steam dumps to cool the primary.  PRT relief lifts at 155 psig dumping into Reactor Containment Building (RCB) sump (no PRT pressure indication easily available). RCB sump pump maintained aligned to pump to Aux Building Sump Tank (ABST).  RCB tanks vented to leaking waste gas header in Aux building.  ABST is nearly full, rupture disk is already failed (has work order against it), so ABST overflows into Aux Building Sump.

00:08:00   The AFW OCIVs are noticed to be closed (view had been blocked by work order tags)  OCIVs are opened spraying max AFW flow onto hot dry SG tubes, water immediately flashes into steam. RCS temperature decreases, but even with max AFW flow, S/G level does not come back on scale until another 14 minutes have elapsed.

00:10:15   Pzr level lowers to be back on scale.  Pzr level lowers rapidly as steam bubbles in core and loops are collapsed.  Staff now believes Trip recovery is normal, Shift Supervisor swaps position with General Foreman,  leaves to help with condensate system restoration (high priority). PRT relief can not pass all of PRT continuing pressure increase, rupture disc fails (195psig) dumping PRT water directly onto RCB floor.

00:19:00 Increasing radiation trend noted on RCB purge exhaust, (no alarms on this system).  High influx of other Control Room Annunciators.  Operators (Unit Supervisor & RO) believe they have a faulted or possible combined faulted ruptured S/G.  AFW is throttled to maintain level in the indicating band in both S/Gs.

00:38:00 PO notices RCB sump pumps are staying on and RCB sump indicator is maxed out at 6 feet. Aux Building rad levels increasing (from sump & leaking waste gas system [fed by PRT water because PRT is water solid]).  RO (with concurrence from SS who is in the Turbine building) orders RCB sump pumps secured.  About 8,000 gallons had been pumped into Aux Building lower level.  The RCPs are beginning to vibrate (indicated on VMS) - due to pumping two phase flow.  Remember the Pzr function is not being performed, so pressure responds to the natural thermodynamic & hydraulic actions resulting from the decay heat source, and RCP & SI pump head.  Steam & water mixture is being swept out of the core via the hot legs.

00:40:00   Ex-Core detectors (Reactor Power Detectors) indicate higher neutron flux than expected after shutdown, operators fear a loss of shutdown margin, impending Rx restart.  The steam voids in the core area allowed a higher neutron leakage factor, thus the higher flux at shutdown was another unrecognized core voiding indication.  RCB now at 170 °F and 2.5 psig.
 
01:00:00 Operators stop trying to regain main condenser function, elect to finish cooldown using S/G PORV’s.

01:11:00 STATUS REPORT -
Condensate System is inoperable,  Pzr level is almost off scale high, it is only being kept on scale by very substantial throttling of SI flow,  Primary system pressure is low at about 1100 psig,  RCP vibration level is increasing, increasing probability of a dreaded seal failure loss of coolant accident (LOCA), RCB sump is at it’s maximum indicated level, RCB temperature and pressure are slowly rising, RCB radiation levels are increasing, Source range count rate is steadily increasing, Suspect ruptured S/G faulted inside containment, RCB emergency cooling is initiated.

01:14:00   RCP vibration continues increasing, RCP amperage decreasing on RCPs.  Pumps with highest vibration (B loop) are stopped.  This is also believed to be the loop with the ruptured/faulted S/G.

01:18:00   Chemistry analysis results received.  RCS boron concentration is low due to Steam condensate dilution, and boron plate out.

01:27:00   The believed faulted/ruptured S/G "B" is isolated.  Removing that portion of the Reactor heat sink, thus increasing the heat load on the "A" S/G.

01:37:00 Noted that "A" S/G level is off scale low.  The S/G had been allowed to become dry, with all feedwater then being flashed to steam as soon as it contacted the tubes allowing RCS temperature to increase, increasing two phase RCS flow through the "A" loop RCPs, significantly increasing their vibration levels.  Aux feedwater flow rate increased to "A" S/G, but recovery is not instant.

01:40:00   The Shift Supervisor returns to the Control Room

01:41:00   "A" loop RCPs secured due to high vibration.  This action removes all forced cooling, core water is boiling off.  Because with large steam voids now forming in the  RCS loops Natural Circulation cooling not possible.  Reflux cooling is the only cooling.

01:42:00 Neutron count rate goes up by a factor of 100 due to decreased shielding (lowering water level) of the Ex-Core detectors.  This was not an actual reactivity increase.  Emergency boration started to prevent re-start. They were not in a restart condition.

01:50:00 The water level drops below the top of the fuel in the core.  Upper portions of fuel rods reached temperatures of about 1500 °F, weakening metal and increasing internal rod pressure.  The upper portions of the rods balloon and then burst.

01:52:00        Although not observed or calculated, "A" loop hot leg temperature corresponds to 47 degrees superheat, will soon run out of range at a temperature corresponding to 109 degrees superheat. The incore thermocouples are maxed out at 700 °F.  Operators believe everything is OK because cold leg temperature is off scale low & average coolant temperature indicates a constant 570 degrees.  (570 is the average between off scale high & off scale low) They do not recognize that they have NO natural circulation flow.

02:00:00 The oncoming watch team comes in to relieve the watch.

02:14:00 RCB air sample monitor rises and goes off scale high. Other RCB & Aux Building rad monitors do the same.  Steam/water slurry carried fuel fragments and fission product gasses are being dumped from the overflowing PRT into the water pond on the containment floor.  Some PRT water is flowing to the leaking vent header piping in the Mechanical Auxiliary Building (MAB) also. Some fuel hot spots are now above 3,800°F.

02:18:00   New operators in the Control Room recognize that the Pzr PORV is open.  PORV Block valve is closed.  SI Injection flow now increased, but unable to start and keep RCPs running.  Operators conclude steam voids exist in loops and core, SI flow is not entering the core.

02:30:00 Cold refueling water storage tank (RWST) water (highly borated water) hits the fuel. The zircaloy-steam exothermic reaction has now heated up portions of the fuel to above 4800 °F.  Zircaloy and fuel are melting.

02:56:00 MAB evacuated.  2 R/hr general area dose.  Letdown sample line is 600R on contact.  Sample bottle is 400R at 1 foot, 1000R on contact.

03:00:00 The steam bubble is blocking SI from effectively cooling the core so a RCP is started for a brief run (19 min)  That will sweep out the steam bubble and allow us to get cold water on the core.  This causes any remaining embrittled fuel in the top of the core to shatter, creating a void.

03:20:00 SI flow with an open PORV is started at 200 minutes covering the fuel within 10 minutes. But the water causes a crust of solidified ceramic material to be formed surrounding the molten fuel and isolating it from receiving any cooling.

03:24:00   General Emergency Declared by Station Manager (highest alert declaration)

03:44:00 The ceramic crust fails, releasing the molten material through the bottom part of the core, melting through the support assembly into the vessel bottom where it is quenched by the water prior to melting through.

04:00:00   Containment Rad Monitor indicates 200 R/hr

04:22:00   Ops determines core is still covered

04:40:00 Containment Rad Monitor now 1000 R/hr

05:00:00 Containment Rad Monitor now 6000 R/hr

05:15:00   Decision made to re-pressurize the RCS to collapse the steam bubbles.  Containment pressure reaches 4.4 psig

06:10:00 High Control Room airborne radioactivity levels, Non essential personnel evacuated

06:17:00   CONTROL ROOM personnel don respirators. Light Core debris and fission products were flushed into RCB and Aux Building through overflows & vents. Multiple auto venting of the VCT to the leaking waste gas header also increased Aux building contamination.

07:00:00   10 Rem/hr in MAB

07:30:00 Lowered RCS pressure to allow Accumulators to inject water into the reactor.

09:00:00 Series of phone calls starts coming in from State of Pennsylvania first requesting, then demanding that that they stop steaming the SG PORVs.

09:15:00 Company VP orders S/G PORVs closed, securing the Natural Circulation reactor core heat sink.  This condition will last for 4.75 hours.  Zirc water/steam reaction increases Hydrogen above the allowed accident values.  Without installed Hydrogen re-combiners the procedures require containment to be vented, but the governor said NO.

09:50:00   RCB pressure spike to 28 psig (the hydrogen is now gone due to recombination)

10:28:00 With now working Pzr heaters, the Pzr reaches saturation, starts pushing water out of hot legs, at first CR personnel do not understand why.

11:10:00 CR operators remove respirators

11:34:00 North Gate at 30 mr/hr

12:45:00   Babcock &Wilcox (reactor designer) trying to get information/advice to Control Room so they will start to establish Subcooling

13:04:00 With subcooling established, RCB & RCDT pressures start long term trend down

14:00:00 Control Room allowed to reopen S/G PORVs

14:35:00 Direct link between Control Room and Babcock &Wilcox is established.

15:50:00 A RCP is successfully restarted & kept running, providing a heat removal path using the Steam Generators (with PORVs) as the decay heat sink

16:00:00 The plant is at last placed in a stable condition

Plant equipment and systems were operated in degraded conditions for extended periods without analysis of the effect these conditions would have in the event of a casualty.

Plant parameter indications, such as levels, temperatures, and other meter readings, were discounted and considered to be faulty without determining by independent verification that the indications were indeed incorrect.  As a result, symptoms of existing plant conditions were misinterpreted, and proper corrective actions were not taken.

Event-based, emergency operating and related training procedures were inadequate for the task of analyzing and reconciling seemingly conflicting plant parameters.  In addition, adherence to procedures was week.  Failure to utilize proper procedures placed the plant in unanalyzed conditions.

Training and qualification of operators was inadequate.  Fundamental misunderstandings of plant behavior, especially the thermodynamic properties of steam and water prevented the proper analysis of reactor coolant system conditions.  In addition, major efforts were expended to restore non-vital plant equipment instead of focusing on the unexplained conditions in the reactor coolant system.
 

Finally, lessons learned from previous similar events were not effectively transmitted throughout the industry.

There was also an inadequacy of design to support safe operation during transients.  Many mandated industry design changes resulted, such as:
 

– Valve Position Indication switches

– Qualified Data Processing System & related data indication systems to calculate subcooled and accident conditions in real-time

– Reactor Vessel Water Level systems were invented and implemented

– Hydrogen Recombiners were installed in all reactor compartments.

– Control Room design and manning requirements were changed.

– An emergency bypass valve is required for all condensate polisher systems.

– An automatic reactor trip on turbine load rejection greater than 50% is the norm.

– Safety Injection pumps are low enough pressure head such that they cannot overpressurize the system.

– Human Engineering requirements

A new, worldwide regulatory body called INPO (International Nuclear Power Organization), made up of peers from all over the world was created.
 
INPO evaluation teams travel to nuclear electric generating facilities to observe operations, analyze processes, shadow personnel, and ask a lot of questions.

With an intense focus on safety and reliability, the evaluation teams assess the:

• Knowledge and performance of plant personnel
• Condition of systems and equipment
• Quality of programs and procedures
• Effectiveness of plant management

Additionally, INPO conducts corporate evaluations that are also focused on safety and reliability.

Training and Accreditation

The  National Academy for Nuclear Training provides training and support for nuclear power professionals.
Nuclear professionals from across the United States – and throughout the world – attend training at the INPO facility in Atlanta and take the various online courses offered by INPO.
In addition, they evaluate individual plant and utility training programs to identify strengths and weaknesses and recommend improvements. Selected operator and technical training programs are accredited through the independent National Nuclear Accrediting Board.

Events Analysis and Information Exchange

INPO assists in reviewing any significant events at nuclear electric generating plants.
Through INPO information exchange and publications, they communicate lessons learned and best practices throughout the nuclear power industry.

Assistance
At the request of individual nuclear electric generating facilities, INPO provides assistance with specific technical or management issues in areas related to plant operation and support.

Originally posted to rickrocket on Fri Apr 03, 2009 at 11:59 AM PDT.

Poll

Is any of the power you use at your home provided by a nuclear power plant?

54%51 votes
23%22 votes
16%15 votes
5%5 votes

| 93 votes | Vote | Results

EMAIL TO A FRIEND X
Your Email has been sent.
You must add at least one tag to this diary before publishing it.

Add keywords that describe this diary. Separate multiple keywords with commas.
Tagging tips - Search For Tags - Browse For Tags

?

More Tagging tips:

A tag is a way to search for this diary. If someone is searching for "Barack Obama," is this a diary they'd be trying to find?

Use a person's full name, without any title. Senator Obama may become President Obama, and Michelle Obama might run for office.

If your diary covers an election or elected official, use election tags, which are generally the state abbreviation followed by the office. CA-01 is the first district House seat. CA-Sen covers both senate races. NY-GOV covers the New York governor's race.

Tags do not compound: that is, "education reform" is a completely different tag from "education". A tag like "reform" alone is probably not meaningful.

Consider if one or more of these tags fits your diary: Civil Rights, Community, Congress, Culture, Economy, Education, Elections, Energy, Environment, Health Care, International, Labor, Law, Media, Meta, National Security, Science, Transportation, or White House. If your diary is specific to a state, consider adding the state (California, Texas, etc). Keep in mind, though, that there are many wonderful and important diaries that don't fit in any of these tags. Don't worry if yours doesn't.

You can add a private note to this diary when hotlisting it:
Are you sure you want to remove this diary from your hotlist?
Are you sure you want to remove your recommendation? You can only recommend a diary once, so you will not be able to re-recommend it afterwards.
Rescue this diary, and add a note:
Are you sure you want to remove this diary from Rescue?
Choose where to republish this diary. The diary will be added to the queue for that group. Publish it from the queue to make it appear.

You must be a member of a group to use this feature.

Add a quick update to your diary without changing the diary itself:
Are you sure you want to remove this diary?
(The diary will be removed from the site and returned to your drafts for further editing.)
(The diary will be removed.)
Are you sure you want to save these changes to the published diary?

Comment Preferences

  •  tips for HP's (24+ / 0-)

    so they can go to license class.

    "If you are going to dance with the Devil, you might as well lead."

    by rickrocket on Fri Apr 03, 2009 at 12:00:15 PM PDT

  •  Clear evidence here that... (1+ / 0-)
    Recommended by:
    bryfry

    ...the massive cover up started with Jimmy Carter who had known nuclear leanings.

  •  diary should have some links (3+ / 0-)

    (0.12, -3.33) ONE America! Yes! We really are ONE America!

    by terrypinder on Fri Apr 03, 2009 at 12:21:52 PM PDT

  •  Am I supposed to be reassured now (2+ / 0-)
    Recommended by:
    rmx2630, linkage

    That nuclear power plant proliferation is nothing to be concerned about?

    That the experts have the situation well in hand?  

    That nuclear waste is not still a problem?

    That we NEED nuclear power in order to survive and thrive on this planet?

    "If you don't read the newspaper, you're uninformed. If you read the newspaper, you're mis-informed." -- Mark Twain

    by ovals49 on Fri Apr 03, 2009 at 12:27:11 PM PDT

    •  Look how fast the frist set of problems came on (5+ / 0-)

      and even though they were in a prohibited situation they managed to contain what could have been a flat disaster.

      Then remember that A) this was 30 years ago with the technology of that time and
      B) that since we have had this happen we now understand in much better way what the consequences are and can regulate it.

      Getting Dems together and keeping them that way is like trying to herd cats, hopped up on crank, through LA, during an earthquake, in the rain. -6.25, -6.10

      by Something the Dog Said on Fri Apr 03, 2009 at 12:30:11 PM PDT

      [ Parent ]

    •  reading the incident reports from an emergency (4+ / 0-)
      Recommended by:
      Joffan, Mcrab, wishbone, rickrocket

      is scary.

      At the turn of the 20th century, the big scary was rail disasters.  Ever hear the childrens' rhyme:

      "Engine engine number nine / racing (1) down Chicago line
      If the train runs off the track (2) / do you want your money back (3)?"

      (1)  reference to unsafe procedures by rail monopolies of the time.
      (2)  reference to frequent fatal derailments
      (3)  reference to callous greedy attitude by rail monopolies

      That little rhyme originated as a biting sarcastic protest of the railroad companies at a time when their power was unchallenged and people were pissed off.  The advent of the Ford Model T was considered nothing less than liberation from the railroads.  

      And have you ever seen pictures of the aftermath of steam explosions on the locomotives of the time?   Hell hath no fury like steam, and accidents of that kind terrified the public.  

      Today rail travel is so safe that we hardly give it a second thought, and automobile accidents take 40,000 lives per year in the US.  

      --

      When TMI happened, I was on the anti-nuclear side of the fence because at that time there was no good solution to waste disposal.   But I also knew enough about how reactors worked, that I ran around my college campus in the Northeast, drawing diagrams on blackboards and explaining to small audiences of fellow students that the risk of events leading to a breach of containment was just about zero.  

      Today France has 20 years of track record safely reprocessing nuclear waste into new nuclear fuel, and the CO2 from coal burning is killing the planet.  

      I switched to the pro-nuclear side in three steps:  

      One, when the first EPA report on climate change came out around 1984: I got a copy (multiple volumes), read through it, and concluded that nuclear waste was hardly as dangerous as "global warming" (as it was called at the time), and that we needed nuclear power as part of the solution to the climate crisis.  

      Two, when I worked on design engineering on a major wind project (300 MW worth, equivalent to about 1/3 of a reactor) and had to deal with the issues attendant to the intermittency of wind.  Having a reactor in the mix where we were working on wind, would have liberated a few more gigawatts (thousands of megawatts) of wind that otherwise can't be utilized.  

      Three, when I found out about France's success dealing with nuclear waste.  That solved the issue that originally had me on the "anti" side.  

      And what's a hell of a lot scarier than reading the stuff from TMI, is reading about what's going to happen if we don't shut down coal burning immediately and switch to climate-clean energy.  At +5 to +6 Celsius, the probability is that humans and most other complex life on Earth will become extinct.  That's what's at stake.  That's why we need to do everything possible to reduce carbon emissions.  And that's why we need nuclear power in the mix, right next to renewables and conservation.  

  •  Oh Christ! Did no one perform (4+ / 0-)
    Recommended by:
    G2geek, linkage, Joffan, rickrocket

    a Failure Mode Analysis on the various component combinations so there would be a clear no go for some of the work order downs?

    This is a damned scary scenario, even though they came through reasonably well. Thank the FSM that the second shift came on with a fresh set of eyes!

    Getting Dems together and keeping them that way is like trying to herd cats, hopped up on crank, through LA, during an earthquake, in the rain. -6.25, -6.10

    by Something the Dog Said on Fri Apr 03, 2009 at 12:28:15 PM PDT

    •  As I understand it, Failure Mode Analyis wasn't (5+ / 0-)

      widely performed anywhere, except maybe by the military and NASA, at the time of TMI. One of the results of TMI was to require plants to perform probabilistic risk assessments. The nuclear industry is now considered a leader in the area.

    •  TMI Was Warned And Responded GET LOST (0+ / 0-)

      See my diary at "The REAL STORY Behind TMI is in My Sig"

      It is obvious that the TMI console operators were never trained to anticipate or handle the situation that Babcock & Wilcox predicted to TMI management.

      My brother chose to stay in the industry and not go overseas, but it's taken 30 years for his income and career to recover from the industry-wide repercussions of TMI. He and his family have gone through some VERY lean times (fortunately, he's doing quite well now after returning to his original employer out of college). If you know any nuclear power engineers who designed reactors "back in the day", you might know my brother (although he probably would not be "willing" to talk openly about TMI).

      When warned by my brother at B&W that the reactor's water release valve could fail if not augmented, 3MI retorted: BS! (3MI saved $70k; the world lost)

      by Robert de Loxley on Sat Apr 04, 2009 at 01:58:45 AM PDT

      [ Parent ]

  •  I might have missed it in your post... (3+ / 0-)
    Recommended by:
    G2geek, caul, linkage

    ... but what went right that prevented TMI from becoming a Chernobyl? Luck that the water in the subvessel was plentiful enough to cool the melting core (@ 3:44:00)?  Did the steam pressure buildup almost explode in the minutes following?  What did explode (as noted in the rec'ced diary)?

    And as far as footnotes/links, just note where you got your timeline info.

    Thanks.

    No snowflake in an avalanche ever feels responsible.

    by Magster on Fri Apr 03, 2009 at 12:30:09 PM PDT

    •  design (8+ / 0-)

      and the fact that we require a containment building.  Chernobyl was a graphite moderated reactor, while TMI-2 is water moderated.  Once the graphite moderator caught fire in Chernobyl, it was all over.  We don't use graphite moderators in the US.

      "If you are going to dance with the Devil, you might as well lead."

      by rickrocket on Fri Apr 03, 2009 at 12:40:33 PM PDT

      [ Parent ]

      •  I just read the wiki on Chernobyl (4+ / 0-)

        My God!  The systemic corruption, end-arounds of safety procedures, incompetence, etc...

        Nuclear power may be safe in theory and the technology is fascinating.  I can certainly see the allure to trying to harness this energy, especially since we're already doing it. But as long as the human element is part of the equation and because there is no margin for error, nuclear power will never be safe.

        No snowflake in an avalanche ever feels responsible.

        by Magster on Fri Apr 03, 2009 at 01:57:13 PM PDT

        [ Parent ]

        •  And, since I just trashed humans (5+ / 0-)

          it's only fair to point out the heroism of the firefighters after the Chernobyl accident, including 3 guys who went into a pool of water under the burning core to open valves to drain the water and prevent another radioactive steam explosion.  Those 3 guys didn't make it out alive, but did their job. Wow!!!

          No snowflake in an avalanche ever feels responsible.

          by Magster on Fri Apr 03, 2009 at 02:01:55 PM PDT

          [ Parent ]

        •  Russians were much sloppier than here, with (1+ / 0-)
          Recommended by:
          Magster

          willful disdain for whistle blowing on safety. But that happens here too, on a less bad scale but consistently. Even the French, who may be the best at it, have their share of coverups of snafus. At least they make better parts-- US plants are usually constructed with parts made in 3d world countries, outsourced on the cheap and not meeting safety standards.

          It's outrageous that this technology is not performed with the highest standards, but US corporations care more about profit.

          Children in the U.S... detained [against] intl. & domestic standards." --Amnesty Internati

          by doinaheckuvanutjob on Fri Apr 03, 2009 at 02:02:29 PM PDT

          [ Parent ]

          •  is Japan (3+ / 0-)
            Recommended by:
            ChurchofBruce, G2geek, bryfry

            is considered a third world country?  They are the only country with steel facilities that can build the plants today.

            "If you are going to dance with the Devil, you might as well lead."

            by rickrocket on Fri Apr 03, 2009 at 02:04:01 PM PDT

            [ Parent ]

            •  Not just steel and not just Japan, but India & (2+ / 0-)
              Recommended by:
              rmx2630, Magster

              China.

              From Energy Bulletin:

              Next U.S. nuclear reactors won't be made in USA
              Many components for those plants will be imported from nations such as France... China and India...

              "So we're gearing up for a real ... global nuclear marketplace where components to be built in Japan or in Sweden or in France or in Italy or in China or in any place," Diaz said.

              The NRC has already issued warnings about counterfeit parts:

              "In recent years many vendors, including foreign companies, with little to no experience in the nuclear industry have entered the market to supply parts and components for both safety and non-safety applications to nuclear power plants," the notice states. "It remains the licensee's responsibility to ensure that all suppliers use standards and processes that conform to US standards. Effective oversight of suppliers becomes increasingly more important as the nuclear industry begins construction of new nuclear power plants in the US."

              Loose parts and valve flow are another documented safety problem.

              Children in the U.S... detained [against] intl. & domestic standards." --Amnesty Internati

              by doinaheckuvanutjob on Fri Apr 03, 2009 at 02:47:12 PM PDT

              [ Parent ]

            •  Only the very largest (1+ / 0-)
              Recommended by:
              G2geek

              of steel components (large forgings) need to be manufactured by the Japanese.

              Fortunately, the US is slowly starting to rebuild is capabilities to build nuclear-grade components.

              For example, there are the B&W facilities in Ohio and Indiana which only a couple of years ago regained their ASME "N-stamp" and there are plans by AREVA and Northrop Grumman Shipbuilding to build large components for new nuclear plants in southeast Virginia.

              Perhaps this idiot thinks that Ohio, Indiana, and Virginia are third world countries, and in fact, I wouldn't be surprised if he or she did, since this is an attitude that I have encountered rather frequently in people from California or New York City.

              An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.
              -- H. L. Mencken

              by bryfry on Fri Apr 03, 2009 at 02:52:23 PM PDT

              [ Parent ]

              •  I'd hr you for calling me an idiot but you're not (1+ / 0-)
                Recommended by:
                caul

                worth it.

                You've shown repeatedly in these discussions on nuke power that you can only resort to insults and belittling others who make points you dislike. Keep it up because you just undermine your cause that way, though it gives you some bizarre self righteous self gratification. Therefore you're not worth my time.

                Children in the U.S... detained [against] intl. & domestic standards." --Amnesty Internati

                by doinaheckuvanutjob on Fri Apr 03, 2009 at 02:55:08 PM PDT

                [ Parent ]

          •  And here is someone (4+ / 0-)
            Recommended by:
            ChurchofBruce, G2geek, Joffan, rickrocket

            who has never heard of the term "nuclear grade."

            Anything going into a nuclear plant that has the slightest association with safety goes through a rigorous QA process.

            An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.
            -- H. L. Mencken

            by bryfry on Fri Apr 03, 2009 at 02:40:23 PM PDT

            [ Parent ]

            •  My experience is entirely military (4+ / 0-)

              does the civilian industry have an equivalent to "subsafe?"

              •  From what I know (3+ / 0-)
                Recommended by:
                ChurchofBruce, G2geek, Joffan

                and don't count me as an expert, I believe that anything designated as a safety system would be equivalent to what you mention as "subsafe."

                The more systems that are considered to be safety systems, the more expensive the components will be, which is why modern designs rely more on passive safety (using the laws of physics instead of moving parts) to provide security against accidents.

                An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.
                -- H. L. Mencken

                by bryfry on Fri Apr 03, 2009 at 02:56:57 PM PDT

                [ Parent ]

                •  Subsafe came from Thresher (5+ / 0-)

                  And was focused on overall pressure hull integrity. They could track components back to the mining and smelting sources.

                  From what I have read about some of the newer current designs they really are phenomenally simpler than what we had. It's quite amazing.

                  But then, we had different operating conditions and design goals, so I don't know if those NEEDED to be complex.

                  •  Well, to put it one way (2+ / 0-)
                    Recommended by:
                    ChurchofBruce, Joffan

                    commercial reactor designers don't have to worry about the possibility that the reactor will find itself suddenly upside down.

                    Not so for naval reactors. It's a whole different world.

                    An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.
                    -- H. L. Mencken

                    by bryfry on Fri Apr 03, 2009 at 08:27:46 PM PDT

                    [ Parent ]

            •  The famous "N-Stamp". (4+ / 0-)
              Recommended by:
              G2geek, Joffan, bryfry, rickrocket

              Facilities are being built in the US (Two that I know of) and every facility around is expanding in terms of nuclear components.

              Nuclear is a growth industry.

              david

              Dr. Isaac Asimov: "The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny ...'"

              by davidwalters on Fri Apr 03, 2009 at 02:52:38 PM PDT

              [ Parent ]

    •  Two physics issues: (2+ / 0-)
      Recommended by:
      Joffan, Mcrab
      1. The reactor had a strong positive void coefficient which meant that displacing water in the core with anything that had a low neutron cross section for absorption would result in adding positive reactivity.
      1. The rod tips were designed for flux shaping and had a fairly low cross section for absorption.

      This means that if you downpower, build up Xe-135, and pull all of your rods out to remain critical, tripping the reactor will result in your rods briefly adding a massive amount of positive reactivity. Thermal feedback will result in forming steam voids in the core which will further increase positive reactivity. The end result is that you have a massive uppower that exceeds the rating of your core.

      For this reason, it is extraordinarily stupid to design a reactor with a positive void coefficient. There are no power reactors in the US that have positive void coefficients.

      •  And for clarity (2+ / 0-)
        Recommended by:
        bryfry, rickrocket

        that's Chernobyl design that BZishi is talking about there.

        Water moderated designs, which includes TMI-2 and all 104 current US power reactors, lose power when steam bubbles form, because the neutron moderating effect of water is more important than the neutron absorption, so reactivity decreases.

        Pebble bed fuel is designed so that they lose reactivity as they get hotter; above operating temperature but well below any melting state.

        Additionally of course TMI-2 was scrammed well before there were any problems. There was no fission going on in the core when it melted; only radioactive decay heat generation from the fission products. Chernobyl was not successfully scrammed.

        This is not a sig-line.

        by Joffan on Sat Apr 04, 2009 at 07:10:53 PM PDT

        [ Parent ]

        •  Uh ... (2+ / 0-)
          Recommended by:
          Joffan, rickrocket

          Chernobyl was not successfully scrammed.

          That's because the reactor blew itself apart in a steam explosion well before it could have scrammed.

          An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.
          -- H. L. Mencken

          by bryfry on Sat Apr 04, 2009 at 09:07:58 PM PDT

          [ Parent ]

          •  Not "well before" (1+ / 0-)
            Recommended by:
            rickrocket

            They were in the process of scramming when it blew apart. I think I read that some rods went in and some jammed, but I wouldn't swear to that one.

            This is not a sig-line.

            by Joffan on Sat Apr 04, 2009 at 09:47:18 PM PDT

            [ Parent ]

            •  The control rods (1+ / 0-)
              Recommended by:
              rickrocket

              were part of the problem.

              The end of the control rods were graphite, which increases moderation, and thus increases reactivity.

              Normally, this is not a problem, since the rods were not supposed to be pulled fully out of the core. That is, the graphite part stayed as the neutron absorbing material was removed. That was the safety procedure.

              For the test that was being run when the accident occurred, however, the operators had pulled the rods fully out (which they were not supposed to do) to keep the reactor running in the configuration that they wanted.

              Thus, when the reactor "scrammed," the graphite went in first, which drove up the reactivity even higher and contributed significantly to the accident. It's a minor point of contention whether the scram was in process or had not actually begun.

              An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.
              -- H. L. Mencken

              by bryfry on Sat Apr 04, 2009 at 10:06:29 PM PDT

              [ Parent ]

  •  Thanks - N/T (3+ / 0-)

    "Upward, not Northward" - Flatland, by EA Abbott

    by linkage on Fri Apr 03, 2009 at 12:51:47 PM PDT

  •  What a horrible diary! (7+ / 0-)

    You call this a diary about Three Mile Island?!!

    There's not a single dead pet or metallic taste mentioned in the whole thing. Pathetic!

    Where is gratuitous praise for Dr. Wing's study? Where is the innuendo of a government cover-up?

    It's a damn shame, but the quality of diaries here on DailyKos is really beginning to plummet.

    ;-)

    An idealist is one who, on noticing that a rose smells better than a cabbage, concludes that it will also make better soup.
    -- H. L. Mencken

    by bryfry on Fri Apr 03, 2009 at 01:37:31 PM PDT

  •  no nukes, none none no more no way (0+ / 0-)

    Fool me once shame on you; fool me twice won't get fooled again. George Bush

    by ganymeade on Fri Apr 03, 2009 at 02:45:56 PM PDT

Subscribe or Donate to support Daily Kos.

Click here for the mobile view of the site