!ALERT! MANUAL SCRAM @ Ind. Point #2 w/10 CONTROL RODS fall loose!

I am stretching my knowledge here given the differences between a nuclear boiler and a conventional boiler, but I am thinking the aux feedwater system would be used ANY time the unit is not online and producing electricity.

Normally the heat from the reactor is carried away by steam that is sent to the turbine generator... when you are only dealing with decay heat you can't make enough steam to send to the turbine, so another cooling system must be used.

You can't send half assed steam to the turbine, the entrained water droplets would erode the blades. Depending on how the plant is designed, low pressure steam can sometimes be vented directly to the condensor, but this could be radioactive steam and so this may not be an option.

Another explanation would be that the damaged MCC also powered the main feedwater pumps, rendering them inoperable.

I initially thought they'd dropped loose of their housing, but that doesn't seem likely as the smolder/fire was in an adjacent building to the control rod mechanism.

I think a lot depends on what "dropped" means. It sounds less controlled than "lowered" but more controlled than "OH MY GOD WHAT HAPPENED IN THERE!"

The thing about the timing of problems was something I was just studying. Neutron poisons build up in reactors to a steady state, but disruptions like this can cause instabilities.

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135Xe effects on restart
Main article: Iodine pit

In a typical nuclear reactor fueled with uranium-235, the presence of 135Xe as a fission product presents designers and operators with problems due to its large neutron cross section for absorption. Because absorbing neutrons can detrimentally affect a nuclear reactor's ability to increase power, reactors are designed to mitigate this effect; operators are trained to properly anticipate and react to these transients.

During periods of steady state operation at a constant neutron flux level, the 135Xe concentration builds up to its equilibrium value for that reactor power in about 40 to 50 hours. When the reactor power is increased, 135Xe concentration initially decreases because the burn up is increased at the new higher power level. Because 95% of the 135Xe production is from decay of iodine-135, which has a 6.57 hour half-life, the production of 135Xe remains constant; at this point, the 135Xe concentration reaches a minimum. The concentration then increases to the new equilibrium level for the new power level in roughly 40 to 50 hours. During the initial 4 to 6 hours following the power change, the magnitude and the rate of change of concentration is dependent upon the initial power level and on the amount of change in power level; the 135Xe concentration change is greater for a larger change in power level. When reactor power is decreased, the process is reversed.

Iodine-135 is a fission product of uranium with a yield of about 6% (counting also the iodine-135 produced almost immediately from decay of fission-produced tellurium-135).[3] This 135I decays with a 6.57 hour half-life to 135Xe. Thus, in an operating nuclear reactor, 135Xe is being continuously produced. 135Xe has a very large neutron absorption cross-section, so in the high neutron flux environment of a nuclear reactor core, the 135Xe soon absorbs a neutron and becomes stable 136Xe. Thus, in about 50 hours, the 135Xe concentration reaches equilibrium where its creation by 135I decay is balanced with its destruction by neutron absorption.

When reactor power is decreased or shut down by inserting neutron absorbing control rods, the reactor neutron flux is reduced and the equilibrium shifts initially towards higher 135Xe concentration. The 135Xe concentration peaks about 11.1 hours after reactor power is decreased. Since 135Xe has a 9.2 hour half-life, the 135Xe concentration gradually decays back to low levels over 72 hours.

The temporarily high level of 135Xe with its high neutron absorption cross-section makes it difficult to restart the reactor for several hours. The neutron absorbing 135Xe acts like a control rod, reducing reactivity. The inability of a reactor to be started due to the effects of 135Xe is sometimes referred to as xenon precluded start-up, and the reactor is said to be "poisoned out". The period of time where the reactor is unable to override the effects of 135Xe is called the xenon dead time.

If sufficient reactivity control authority is available, the reactor can be restarted, but a xenon burn-out transient must be carefully managed. As the control rods are extracted and criticality is reached, neutron flux increases many orders of magnitude and the 135Xe begins to absorb neutrons and be transmuted to 136Xe. The reactor burns off the nuclear poison. As this happens, the reactivity and neutron flux increases, and the control rods must be gradually reinserted to counter the loss of neutron absorption by the 135Xe. Otherwise, the reactor neutron flux will continue to increase, burning off even more xenon poison, on a path to runaway criticality. The time constant for this burn-off transient depends on the reactor design, power level history of the reactor for the past several days, and the new power setting. For a typical step up from 50% power to 100% power, 135Xe concentration falls for about 3 hours.

Failing to anticipate and manage xenon poisoning and compensate for the subsequent burn-off properly was a contributing factor to the Chernobyl disaster; during a run-down to a lower power, a combination of operator error and xenon nuclear poisoning caused the reactor thermal power to fall to near-shutdown levels. The crew's resulting efforts to restore power, including the manual withdrawal of control rods not under the SKALA computer's automated control, placed the reactor in a highly unsafe configuration. A failed SCRAM procedure, resulting in the control rods being jammed at a level that actually increased reactivity, caused a thermal transient and a steam explosion that tore the reactor apart.
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[link to en.wikipedia.org (secure)]
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aHEMagain

Last Edited by aHEMagain^2 on 12/07/2015 07:22 PM

Are you stocked up on your iodine!?!

AC 70815046 has confirmed to me details that tells me in fact he is an employee at Indian point.

why another thread

AC posting is the real deal

if he is not concerned just chill

That was my first thought too.
These are dropped CONTROL RODS....if anything that should SLOW DOWN any reactions at the core, not make it go BOOM.

huh.... you saying you work there?

No but I have worked at a power plant about a half a mile from there, and AC confirmed facts that only someone in the power generation industry in that area would know.

The reactor was shutdown on saturday and the control rods did what they are supposed to do.

I didn't know they shutdown the second reactor though.

Doesn't look like both are shut down.

Power Reactor Event Number: 51586
Facility: INDIAN POINT
Region: 1 State: NY
Unit: [2] [ ] [ ]
RX Type: [2] W-4-LP,[3] W-4-LP
NRC Notified By: CHEE YUN
HQ OPS Officer: JOHN SHOEMAKER Notification Date: 12/05/2015
Notification Time: 18:48 [ET]
Event Date: 12/05/2015
Event Time: 17:31 [EST]
Last Update Date: 12/05/2015
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
WILLIAM COOK (R1DO)
SCOTT MORRIS (NRR)
BERNARD STAPLETON (IRD)

Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode
2 M/R Y 100 Power Operation 0 Hot Standby
Event Text
MANUAL REACTOR TRIP INITIATED DUE TO MULTIPLE DROPPED CONTROL RODS

"At 1731 [EST] on December 5, 2015, Indian Point Unit 2 Control Room operators initiated a Manual Reactor Trip due to indications of multiple dropped Control Rods. The initiating event was a smoldering Motor Control Center (MCC) cubicle in the Turbine Building that supplies power to the Rod Control System. The unit is stable in Mode 3 with heat sink provided by Auxiliary Feedwater and decay heat removal is via the steam dumps to the condenser. Offsite Power remains in service.

"The smoldering MCC cubicle had power removed from it when 24 MCC breaker tripped on overcurrent. The affected cubicle has ceased smoldering and is being monitored by on-site Fire Brigade trained personnel. The trip of 24 MCC removed power to 22 Battery Charger, 22 DC Bus remained powered from the 22 Battery without interruption, and 22 Battery Charger was subsequently repowered."

The cause of the smoldering MCC is being investigated and a post reactor trip evaluation is being conducted by the licensee. There was no impact on Unit 3, which continues to operate at 100% power.

The licensee has notified the NRC Resident Inspector and appropriate State and Local authorities.

:dancing ra::dancing ra::dancing ra:


the rods dropped

what happens when the rods drop ??

what happens ????????


:dancing ra::dancing ra::dancing ra:

Nothing... Just has some work before they can turn it back on.

It wouldn't make sense to shut down the other unit, that would be bad for the gird in general, making a blackout more likely, and if that were to happen they would be relying on diesel generators for feedwater pump power, and those things are not that reliable.

The other unit surely has it's own control cabinet for it's control rods, so this failure would not affect it.

you nailed it

On a side note, being winter time the grid would not be in much trouble at all if Indian Point went down, we are in a good time of year for low power demand, not too cold, not too hot.

There are shit tons of gas turbine plants that are idle right now, their main turbines could be online in 10 minutes and their steam turbines online about an hour later.

That is the information we have.

When the rods accidentally dropped, operators initiated a Manual Reactor Trip. This means the rest of the control rods were inserted into the reactor core, shutting down the reaction before the situation became more serious.

Really?! Who drops a fuel rod?

Not fuel rod, control rod made of non-nuclear material.

Those that think this is a deadly situation, need a little more education.

It is not a deadly situation-at this time--according to reports.

It COULD have been--but the time frame for that happening is now past thank GOD. Vigilance is to be advised considering the dearth of information and transparency that has resulted from Fukushima. Most of the general public has no conception of what and how these energy sources work.

Education is key. Knowledge is power. Information is vital.



[link to www.youtube.com (secure)]

Thread: Breaking: NY POWER PLANT UNEXPECTEDLY SHUT DOWN

Yeah it seems the headless just can't wait for the Lake of Fire and Brimstone. They just keep on pushing their luck.

Let's try to remember what happened at our advanced nuclear plants in Japan.
After losing power, then NOT leaving the site as they were instructed the technical people were keeping the pile cool by using their car batteries to operate the 24 volt DC control systems.
As the car batteries died they passed the need onto their superior staff.
Helecopters dropped batteries on site.
They were of the wrong voltage and so large that they could not be moved to the control panels in the building.
Result, after many hours of valiant effort the plant was lost.
Car batteries
Just car batteries
Simple
Easy
Total screw up
Let's keep this in our minds.

We have had cores with damaged rod because of bad fme practices with no doom. Our systems are robust.

Sorry about the double copy lol

Yah I've never heard of fuel rods being moved outside of a refuel outage.

Just thought about it. Strange that there is this many on GLP from that industry considering the small size of the people in it. Guess its true that you have to be at least a little crazy to go into the can/vc lol.