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Monday, July 16, 2012

Inside Whistler blower lays bare the greedy decisions that have brought SORE San Onofre Reactor Emergency to it's broken knees

 http://www.greentechmedia.com/articles/read/How-Broken-is-the-San-Onofre-Nuclear-Plant/

Begoodto

Look. This problem existed in their previous Steam Generators. Alot of tube wear around the anti-vibration bars or batwing supports. Alot of wear....... leaks too. The problem was never fully addressed, along with the monumental safety implications. I tried to address it, but I will not get into that at this time.

This problem was also accompanied by fuel cladding breeches (failed fuel). It was a radiological mess. SCE was not fully upfront with the NRC about this problem and other issues, and now they are paying the price.

From my experience, significant fuel cladding breeches in Unit 2 will appear in November - December 2012 based on a startup of Unit 2 in August 2012. This is all based on past experience and modeled as such. The Xenon and Krypton offgasing from the cladding failures will be beyond the plants capacity to pr...ocess. In PWR's where fuel cladding is compromised, xenon gas (from the failed fuel) emits gamma rays, which then decays to Strontium 90 and various isotopes of Cesium settling out on the ground, all with 30 year half lifes.

Krypton is another mean beast. This is emitted mainly out the plant vent stack. Some of it is controlled, but at times, the pressure diaphrams can burst on the pressurized tanks and the release is uncontrolled. In addition, the irradiated U235 and UO2 can escape the primary system, with a degraded secondary barrier (steam generators) as fast as the atmospheric conditions prevail in any reactor shutdown or anticipated transient.

Even though, there are Technical Specification Limits on primary system Iodine activity, walkdowns by NRC inspectors must be mandatory around the RCS sampling system penetrations and radiation monitors to ensure operability and correct sampling alignment. Furthermore, a 30 sq. in. high energy primary blowdown (roughly 25 tubes in all) into the secondary side of the steam generators will result in an unacceptable peak cladding temperature.

Those steam generator safeties that do not stick open will be ripped off their headers, creating a path from the fuel to the outside atmosphere. With the steam binding in the core and the later condensed positive reactivity insertion, the sky is the limit for the offsite dose. I was a shift technical advisor and engineer there at San Onofre Units 2&3 during the startup phase and full power operations. We had the same leak problems with the CE Inconel 600 S/G's. It was a flow induced vibration problem, resulting in many tubes being plugged. There was also alot of leaks beyond Technical Specification Limits. Nothing has really changed, IMO, other than the NRC was present in the control room when the leak occurred with the new S/G's, otherwise you may never have heard about it, based on their PR comments: "The leak was initially estimated at a rate of 85 gallons a day — an amount about half of what would require the plant to shut down. Alexander said the rate of the leak was "much less," but did not provide a figure."

The NRC stated that was not true. The problem as I see it now, for the most part, partially eminates from the primary core, just as I suspected last time. With the old CE S/G's, operation continued for a long period of time with this vibration problem, resulting in a high level of failed fuel. I figured 2.5%. Could have been as high as 5%.

That's alot of fuel that was oxidized and displaced from the cladding. A USNRC Inspector contacted a radiation induced luekemia in 1983-1984 at the onset of a "fuel flea" problem (actually failed fuel, irradiated UO2 and U235). As operation continued, the problem got progressively worse with excessive cladding breeches. There were other cancers too. I figured 2.5% in early 1985, with the site's Computer Manager and Physicist stating "2%" My observation of that with the FIV problem was that the reactor coolant pump seal differential pressures where oscillating violently at the onset of this problem, due to a pulsating flow in the core. This resulted in many seal failures. The other observation was with the excore neutron detectors which was emitting ALOT of noise, causing reactor trips on the Core Protection Calculators. This noise as I saw it was due to a primary flow induced vibration problem, in the core, which could actually be calculated with a pattern in frequency and amplitude. The problem, as I recall was corrected without a competent safety review. SCE actually modified the excore output signals to keep the CPC's from tripping the reactor in 2/4 channels, when IMO, the excores were relaying some very valuable information to management. The CPC's "wanted" the reactor turned off, if you will. EVEN THEY TRIED TO FULFILL THEIR SAFETY FUNCTION.

I really do not see a change in S/G issues between now and the 1980's. What I see is a FIV (flow induced vibration) problem that is designed into the NSSS (Nuclear Steam Supply System). It occurs on both the primary and secondary sides of the NSSS. If operation continues, even with tubes plugged, the fuel will begin to fail, as last time, with ANOTHER radiological mess on their hands for the plant populus and even the general public.

The fuel always has defects, some of it manufactured with an unwanted moisture content. The primary vibration problem expedites the destruction of the cladding. I never got the opportunity to correlate the RCP (reactor coolant pump) differential pressure swings with the excore detector noise, but there was a pattern. As time passed on, those tubes suffering the greatest amplitudes from the FIV were removed from service, but a lingering safety issue still exists as the secondary barrier to fission product release (steam generator tubes) is already compromised by design. The problem has multiple root causes;
1. primary core FIV.
2. Secondary side S/G tube FIV.
3. The way the NSSS is pinned and sprung is "straight out of the twilight zone". It's a compromise between seismic issues and Flow Induced Vibration considerations.
4. SCE had no problem feeding their CE Inconel 600 S/G's with sea water all the way to the MSIV's (main steam isolation valves).
5. SCE lacked suitable inventory control of failed fuel. The fuel should be removed from the core, now, and sipped to establish baseline data and suitability for operation.
6. SCE never fully understood the root cause of the problem with their older S/G's, but did an excellent job of covering up the effects.

Now, they are paying the price.

Dan Johnson

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