I can't tell if your first sentence is implying that you did follow this saga over the past few years, but if so it's very strange that someone who professes to be intimate with the details here would leave out that the reason they couldn't deliver on planned budgets and schedules was massive accounting fraud, not a failure in their engineering or product management.
Yes, I have been following the progress of AP1000 reactor projects for years. The Toshiba accounting scandal surely doesn't help but I don't believe it is the proximate cause for Westinghouse's bankruptcy. Toshiba's accounting irregularities aren't even mentioned in the bankruptcy declaration.
From the bankruptcy declaration:
As described in more detail below, the Debtors’ need to avail themselves of the protections of the Bankruptcy Code arises primarily from a series of unforeseen challenges that significantly delayed and increased the cost of construction of the nuclear plants in Georgia and South Carolina (referred to as Vogtle and VC Summer, respectively). These challenges potentially expose the Debtors to billions of dollars either in (i) cost overruns to complete the projects or (ii) penalties and liabilities if they abandon the projects. The Debtors cannot afford either option. Notwithstanding that the Debtors’ other businesses are profitable and world-class, the Construction Business cost increases have led to a liquidity crisis that the Debtors can only solve in chapter 11.
...
The Construction Business division delivers both new-plant projects and major projects for new and already operating nuclear power plants globally. It consists of two business segments: (1) engineering, procurement, and construction (“EPC”) services for customers around the globe, primarily offering the AP1000 technology; and (2) engineering and procurement (“E&P”) services, such as design, equipment, and site installation and startup support, to both AP1000 and non AP1000 projects. While some portions of the Construction Business are profitable, the main portion of the EPC business, which constructs the Vogtle and VC Summer projects, has damaged the profitability of the entire Construction Business. As a result, the Construction Business generated EBITDA from FY2013 to FY2015 of negative $343 million. As described in detail below, these losses have accelerated in the past 15 months following the Company’s purchase of CB&I Stone & Webster, Inc. (“S&W”).
(Thanks to mikikian for linking this declaration elsewhere in the discussion. All of Part III, "Events Leading to Chapter 11", is worth reading.)
EDIT: if you're talking about the valuation dispute around the Chicago Bridge & Iron acquisition, pg 22, that is presented as a $2 billion problem. The construction projects have another $6 billion worth of expenses now estimated necessary to complete before 2020 (pg 23-24). It's not clear that Westinghouse could dig itself out of this hole even if the money pit was only $6 billion deep instead of $8 billion.
